Sample records for drought tolerance gradient
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Tolerance to multiple climate stressors: A case study of Douglas-fir drought and cold hardiness
Bansal, Sheel; Harrington, Constance A; St. Clair, John Bradley
2016-01-01
Summary: 1. Drought and freeze events are two of the most common forms of climate extremes which result in tree damage or death, and the frequency and intensity of both stressors may increase with climate change. Few studies have examined natural covariation in stress tolerance traits to cope with multiple stressors among wild plant populations. 2. We assessed the capacity of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii), an ecologically and economically important species in the northwestern USA, to tolerate both drought and cold stress on 35 populations grown in common gardens. We used principal components analysis to combine drought and cold hardiness trait data into generalized stress hardiness traits to model geographic variation in hardiness as a function of climate across the Douglas-fir range. 3. Drought and cold hardiness converged among populations along winter temperature gradients and diverged along summer precipitation gradients. Populations originating in regions with cold winters had relatively high tolerance to both drought and cold stress, which is likely due to overlapping adaptations for coping with winter desiccation. Populations from regions with dry summers had increased drought hardiness but reduced cold hardiness, suggesting a trade-off in tolerance mechanisms. 4. Our findings highlight the necessity to look beyond bivariate trait–climate relationships and instead consider multiple traits and climate variables to effectively model and manage for the impacts of climate change on widespread species.
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Moody, Eric K.; Sabo, John L.
2013-01-01
Shifts in plant species distributions due to global change are increasing the availability of novel resources in a variety of ecosystems worldwide. In semiarid riparian areas, hydric pioneer tree species are being replaced by drought-tolerant plant species as water availability decreases. Additionally, introduced omnivorous crayfish, which feed upon primary producers, allochthonous detritus, and benthic invertebrates, can impact communities at multiple levels through both direct and indirect effects mediated by drought-tolerant plants. We tested the impact of both virile crayfish (Orconectes virilis) and litter type on benthic invertebrates and the effect of crayfish on detrital resources across a gradient of riparian vegetation drought-tolerance using field cages with leaf litter bags in the San Pedro River in Southeastern Arizona. Virile crayfish increased breakdown rate of novel drought-tolerant saltcedar (Tamarix ramosissima), but did not impact breakdown of drought-tolerant seepwillow (Baccharis salicifolia) or hydric Fremont cottonwood (Populus fremontii) and Gooding's willow (Salix goodingii). Effects on invertebrate diversity were observed at the litter bag scale, but no effects were found at the cage scale. Crayfish decreased alpha diversity of colonizing macroinvertebrates, but did not affect beta diversity. In contrast, the drought-tolerant litter treatment decreased beta diversity relative to hydric litter. As drought-tolerant species become more abundant in riparian zones, their litter will become a larger component of the organic matter budget of desert streams which may serve to homogenize the litter-dwelling community and support elevated populations of virile crayfish. Through impacts at multiple trophic levels, crayfish have a significant effect on desert stream ecosystems. PMID:23667600
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Holmgren, Milena; Gómez-Aparicio, Lorena; Quero, José Luis; Valladares, Fernando
2012-06-01
The combined effects of shade and drought on plant performance and the implications for species interactions are highly debated in plant ecology. Empirical evidence for positive and negative effects of shade on the performance of plants under dry conditions supports two contrasting theoretical models about the role of shade under dry conditions: the trade-off and the facilitation hypotheses. We performed a meta-analysis of field and greenhouse studies evaluating the effects of drought at two or more irradiance levels on nine response variables describing plant physiological condition, growth, and survival. We explored differences in plant response across plant functional types, ecosystem types and methodological approaches. The data were best fit using quadratic models indicating a humped-back shape response to drought along an irradiance gradient for survival, whole plant biomass, maximum photosynthetic capacity, stomatal conductance and maximal photochemical efficiency. Drought effects were ameliorated at intermediate irradiance, becoming more severe at higher or lower light levels. This general pattern was maintained when controlling for potential variations in the strength of the drought treatment among light levels. Our quantitative meta-analysis indicates that dense shade ameliorates drought especially among drought-intolerant and shade-tolerant species. Wet tropical species showed larger negative effects of drought with increasing irradiance than semiarid and cold temperate species. Non-linear responses to irradiance were stronger under field conditions than under controlled greenhouse conditions. Non-linear responses to drought along the irradiance gradient reconciliate opposing views in plant ecology, indicating that facilitation is more likely within certain range of environmental conditions, fading under deep shade, especially for drought-tolerant species.
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Polley, H Wayne; Tischler, Charles R; Johnson, Hyrum B; Derner, Justin D
2002-04-01
Traits that promote rapid growth and seedling recruitment when water is plentiful may become a liability when seedlings encounter drought. We tested the hypothesis that CO2 enrichment reinforces any tradeoff between growth rate and drought tolerance by exaggerating interspecific differences in maximum relative growth rate (RGR) and survivorship of drought among seedlings of five woody legumes. We studied invasive species of grasslands that differ in distribution along a rainfall gradient. Survivorship of drought at ambient CO2 concentration ([CO2]) was negatively related to RGR in well-watered seedlings in one of two experiments, but the relationship was weak because interspecific differences in RGR were small. Contrary to our hypothesis, there was no significant relationship among well-watered seedlings between RGR at ambient [CO2] and either the relative or absolute increase in RGR at elevated [CO2]. As predicted, however, CO2 enrichment reinforced interspecific differences in survivorship of seedlings exposed to similar rates of soil water depletion. Doubling [CO2] improved seedling survivorship of the most drought-tolerant species throughout the period of soil water depletion, but did not consistently affect survivorship of more drought-sensitive species. Midday xylem pressure potentials of drought-treated seedlings were less negative at elevated [CO2] than at ambient [CO2], but no other measured trait was consistently correlated with improved survivorship at high [CO2]. Carbon dioxide enrichment may not reinforce species differences in RGR, but could exaggerate interspecific differences in drought tolerance. To the extent that seedling persistence in grasslands correlates with drought survivorship, our results indicate a positive effect of CO2 enrichment on recruitment of woody legumes that are currently tolerant of drought.
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Pineda-García, Fernando; Paz, Horacio; Meinzer, Frederick C; Angeles, Guillermo
2016-02-01
In seasonal plant communities where water availability changes dramatically both between and within seasons, understanding the mechanisms that enable plants to exploit water pulses and to survive drought periods is crucial. By measuring rates of physiological processes, we examined the trade-off between water exploitation and drought tolerance among seedlings of trees of a tropical dry forest, and identified biophysical traits most closely associated with plant water-use strategies. We also explored whether early and late secondary successional species occupy different portions of trade-off axes. As predicted, species that maintained carbon capture, hydraulic function and leaf area at higher plant water deficits during drought had low photosynthetic rates, xylem hydraulic conductivity and growth rate under non-limiting water supply. Drought tolerance was associated with more dense leaf, stem and root tissues, whereas rapid resource acquisition was associated with greater stem water storage, larger vessel diameter and larger leaf area per mass invested. We offer evidence that the water exploitation versus drought tolerance trade-off drives species differentiation in the ability of tropical dry forest trees to deal with alternating water-drought pulses. However, we detected no evidence of strong functional differentiation between early and late successional species along the proposed trade-off axes, suggesting that the environmental gradient of water availability across secondary successional habitats in the dry tropics does not filter out physiological strategies of water use among species, at least at the seedling stage. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
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Thirunavukkarasu, Nepolean; Hossain, Firoz; Arora, Kanika; Sharma, Rinku; Shiriga, Kaliyugam; Mittal, Swati; Mohan, Sweta; Namratha, Pottekatt Mohanlal; Dogga, Sreelatha; Rani, Tikka Shobha; Katragadda, Sumalini; Rathore, Abhishek; Shah, Trushar; Mohapatra, Trilochan; Gupta, Hari Shankar
2014-12-24
Earlier studies were focused on the genetics of temperate and tropical maize under drought. We identified genetic loci and their association with functional mechanisms in 240 accessions of subtropical maize using a high-density marker set under water stress. Out of 61 significant SNPs (11 were false-discovery-rate-corrected associations), identified across agronomic traits, models, and locations by subjecting the accessions to water stress at flowering stage, 48% were associated with drought-tolerant genes. Maize gene models revealed that SNPs mapped for agronomic traits were in fact associated with number of functional traits as follows: stomatal closure, 28; flowering, 15; root development, 5; detoxification, 4; and reduced water potential, 2. Interactions of these SNPS through the functional traits could lead to drought tolerance. The SNPs associated with ABA-dependent signalling pathways played a major role in the plant's response to stress by regulating a series of functions including flowering, root development, auxin metabolism, guard cell functions, and scavenging reactive oxygen species (ROS). ABA signalling genes regulate flowering through epigenetic changes in stress-responsive genes. ROS generated by ABA signalling are reduced by the interplay between ethylene, ABA, and detoxification signalling transductions. Integration of ABA-signalling genes with auxin-inducible genes regulates root development which in turn, maintains the water balance by regulating electrochemical gradient in plant. Several genes are directly or indirectly involved in the functioning of agronomic traits related to water stress. Genes involved in these crucial biological functions interacted significantly in order to maintain the primary as well as exclusive functions related to coping with water stress. SNPs associated with drought-tolerant genes involved in strategic biological functions will be useful to understand the mechanisms of drought tolerance in subtropical maize.
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NASA Astrophysics Data System (ADS)
Powell, T.; Kueppers, L. M.; Koven, C.; Johnson, D. J.; Faybishenko, B.; McDowell, N. G.; Chambers, J. Q.
2016-12-01
Land surface models that include demographic and plant hydrodynamic processes are promising tools for characterizing how different drought scenarios may affect carbon cycling of tropical forests. The Ecosystem Demography (ED2) model, now formulated with such features, was used to evaluate how different drought scenarios affect mortality patterns, functional diversity and coexistence of four plant functional types (PFTs) of tropical trees at Barro Colorado Island (BCI), Panama. The four PFTs simulated were early- versus late-successional groups subdivided into drought-tolerant versus -intolerant groups. The hydrodynamic formulation enables the four PFTs to compete mechanistically along two largely orthogonal resource gradients of water and light. The model simulations produced considerable differences in the aboveground biomass response to contrasting drying scenarios that included longer dry seasons, El Nino related droughts, and drier dry seasons. The emergent mortality dynamics reflect the physiological trade-off between water-use and carbon fixation formulated by the hydrodynamic regulation over stomatal conductance. During dry periods, the model predicts increased mortality rates of pioneer trees compared to generalists and drought-intolerant trees compared to -tolerant trees. The model also predicts that surviving cohorts in the smallest size classes of drought-intolerant trees are occasionally primed for release from competition following acute droughts. Observations at BCI showed increased mortality rates for large trees (i.e. >30 cm dbh) during the 1982 El Nino drought, but not subsequent El Nino related droughts. The causes of the elevated mortality rates are explored with the model. Coexistence of four plant functional types in the model is highly sensitive to the parameterization of stem hydraulic conductivity; but, surprisingly not very sensitive to shifts in rainfall patterns. These results demonstrate (a) that plant hydrodynamics are critical for simulating dynamic mortality patterns between drought-tolerant and -intolerant PFTs in order to increase representation of functional diversity in land surface models, and (b) that more demographic, plant hydraulic and deeper soil moisture observations are required to constrain hydrodynamic parameter selection.
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Turyagyenda, Laban F.; Kizito, Elizabeth B.; Ferguson, Morag; Baguma, Yona; Agaba, Morris; Harvey, Jagger J. W.; Osiru, David S. O.
2013-01-01
Cassava is an important root crop to resource-poor farmers in marginal areas, where its production faces drought stress constraints. Given the difficulties associated with cassava breeding, a molecular understanding of drought tolerance in cassava will help in the identification of markers for use in marker-assisted selection and genes for transgenic improvement of drought tolerance. This study was carried out to identify candidate drought-tolerance genes and expression-based markers of drought stress in cassava. One drought-tolerant (improved variety) and one drought-susceptible (farmer-preferred) cassava landrace were grown in the glasshouse under well-watered and water-stressed conditions. Their morphological, physiological and molecular responses to drought were characterized. Morphological and physiological measurements indicate that the tolerance of the improved variety is based on drought avoidance, through reduction of water loss via partial stomatal closure. Ten genes that have previously been biologically validated as conferring or being associated with drought tolerance in other plant species were confirmed as being drought responsive in cassava. Four genes (MeALDH, MeZFP, MeMSD and MeRD28) were identified as candidate cassava drought-tolerance genes, as they were exclusively up-regulated in the drought-tolerant genotype to comparable levels known to confer drought tolerance in other species. Based on these genes, we hypothesize that the basis of the tolerance at the cellular level is probably through mitigation of the oxidative burst and osmotic adjustment. This study provides an initial characterization of the molecular response of cassava to drought stress resembling field conditions. The drought-responsive genes can now be used as expression-based markers of drought stress tolerance in cassava, and the candidate tolerance genes tested in the context of breeding (as possible quantitative trait loci) and engineering drought tolerance in transgenics. PMID:23519782
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Response of antioxidant system to drought stress and re-watering in Alfalfa during branching
NASA Astrophysics Data System (ADS)
Tina, R. R.; Shan, X. R.; Wang, Y.; Guo, S. Y.; Mao, B.; Wang, W.; Wu, H. Y.; Zhao, T. H.
2017-11-01
This paper aimed to reveal the response mechanism of active oxygen metabolism and antioxidant enzyme activities in Alfalfa under drought stress and re-watering, and the pot experiment was used, to explore the changes of H2O2, O2·-, electrolyte leakage conductivity and MDA, SOD, POD, CAT activity in Golden Empress (tolerant cultivar) and Sanditi (non-tolerant cultivar) under drought stress and re-watering during branching stage. Three water gradients were set up: CK (Maximum field capacity of 75%±5%), T1 (Maximum field capacity of 45%±5%), T2 (Maximum field capacity of 35%±5%) to compare, and the drought rehydration was also studied. Results: the results indicated that H2O2 content, O2·-production rate, relative conductivity and MDA content were higher than the control, and the increase extent of Golden Empress was higher than the Sanditi under drought stress and after re-watering the recovery capability of Golden Empress was also higher than the Sanditi. After 7 days of re-watering, all indexes were restored to the control level, indicating that the re-watering have compensation effect after drought. After drought stress, to weaken the damage of active oxygen Golden Empress was mainly by increasing the activity of POD and SOD, but Sanditi was mainly through the POD and CAT activity increased to effectively remove ROS. Under drought stress, active oxygen in leaves of Alfalfa increased, and thus the membrane system was damaged which lead to the increase of MDA content and relative electric conductivity. Plants play a defensive role by increasing the activity of antioxidant enzymes and scavenging reactive oxygen species. After re-watering, the stress effect was reduced, and the physiological indexes of plants were restored to the control level. In general, tolerant cultivar has stronger antioxidant properties under drought and re-watering.
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Impact of drought on plant populations of native and invasive origins.
Kleine, Sandra; Weissinger, Lisa; Müller, Caroline
2017-01-01
Invasive populations often shift phenotypically during introduction. Moreover, they are postulated to show an increased phenotypic plasticity compared with their native counterparts, which could be advantageous. However, less is known about trait selection across populations along the invasion gradient in response to environmental factors, such as increasing drought caused by climate change. In this study, we investigated the impacts of drought on growth, regrowth, and various leaf traits in plants of different origin. Therefore, seeds of 18 populations of the perennial Tanacetum vulgare were collected along the invasion gradient (North America, invasive; West Europe, archaeophyte; East Europe, native) and grown in competition with the grass Poa pratensis under control or dry conditions in a common garden. Above-ground biomass was cut once and the regrowth was measured as an indicator for tolerance over a second growth period. Initially, drought had little effects on growth of T. vulgare, but after cutting, plants grew more vigorously. Against expectations, phenotypic plasticity was not higher in invasive populations, but even reduced in one trait, which may be attributable to ecological constraints imposed by multiple stress conditions. Trait responses reflected the range expansion and invasion gradient and were influenced by the latitudinal origin of populations. Populations of invaded ranges may be subject to faster and more extensive genetic mixing or had less time to undergo and reflect selective processes.
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USDA-ARS?s Scientific Manuscript database
A panel of alfalfa cultivars and landraces originated worldwide with potential value of drought tolerance were selected from USDA-Western Region Plant Germplasm Center. Field trials were conducted in the in Roza farm in Prosser, WA and a gradient of water deficits were applied. Aboveground biomass w...
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Nyarukowa, Christopher; Koech, Robert; Loots, Theodor; Apostolides, Zeno
2016-07-01
Climate change is causing droughts affecting crop production on a global scale. Classical breeding and selection strategies for drought-tolerant cultivars will help prevent crop losses. Plant breeders, for all crops, need a simple and reliable method to identify drought-tolerant cultivars, but such a method is missing. Plant metabolism is often disrupted by abiotic stress conditions. To survive drought, plants reconfigure their metabolic pathways. Studies have documented the importance of metabolic regulation, i.e. osmolyte accumulation such as polyols and sugars (mannitol, sorbitol); amino acids (proline) during drought. This study identified and quantified metabolites in drought tolerant and drought susceptible Camellia sinensis cultivars under wet and drought stress conditions. For analyses, GC-MS and LC-MS were employed for metabolomics analysis.%RWC results show how the two drought tolerant and two drought susceptible cultivars differed significantly (p≤0.05) from one another; the drought susceptible exhibited rapid water loss compared to the drought tolerant. There was a significant variation (p<0.05) in metabolite content (amino acid, sugars) between drought tolerant and drought susceptible tea cultivars after short-time withering conditions. These metabolite changes were similar to those seen in other plant species under drought conditions, thus validating this method. The Short-time Withering Assessment of Probability for Drought Tolerance (SWAPDT) method presented here provides an easy method to identify drought tolerant tea cultivars that will mitigate the effects of drought due to climate change on crop losses. Copyright © 2016. Published by Elsevier GmbH.
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Zhang, Xiaojing; Liu, Xuyang; Zhang, Dengfeng; Tang, Huaijun; Sun, Baocheng; Li, Chunhui; Hao, Luyang; Liu, Cheng; Li, Yongxiang; Shi, Yunsu; Xie, Xiaoqing; Song, Yanchun; Wang, Tianyu; Li, Yu
2017-01-01
Drought is a major threat to maize growth and production. Understanding the molecular regulation network of drought tolerance in maize is of great importance. In this study, two maize inbred lines with contrasting drought tolerance were tested in the field under natural soil drought and well-watered conditions. In addition, the transcriptomes of their leaves was analyzed by RNA-Seq. In total, 555 and 2,558 genes were detected to specifically respond to drought in the tolerant and the sensitive line, respectively, with a more positive regulation tendency in the tolerant genotype. Furthermore, 4,700, 4,748, 4,403 and 4,288 genes showed differential expression between the two lines under moderate drought, severe drought and their well-watered controls, respectively. Transcription factors were enriched in both genotypic differentially expressed genes and specifically responsive genes of the tolerant line. It was speculated that the genotype-specific response of 20 transcription factors in the tolerance line and the sustained genotypically differential expression of 22 transcription factors might enhance tolerance to drought in maize. Our results provide new insight into maize drought tolerance-related regulation systems and provide gene resources for subsequent studies and drought tolerance improvement. PMID:28700592
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NASA Astrophysics Data System (ADS)
Méndez-Toribio, M.; Ibarra-Manríquez, G.; Navarrete-Segueda, A.; Paz, H.
2017-08-01
In seasonal plant communities, it is recognized that topography-related variation in water availability and solar radiation determine vegetation structure and community composition; however, the effects on functional structure, particularly through changes in resource use strategies of plants are still poorly understood. This study examines the effects of slope aspect and topographic position on functional trait dominance in a tropical dry forest landscape and explores whether strategies for coping with drought (avoidance vs. tolerance) segregate spatially along the water stress gradient created by the interaction of these two topographic factors. The study was conducted in the Balsas river basin in south-central Mexico. Functional traits were evaluated in 63 species of trees (≥ 2.5 cm diameter at breast height) dominant in plots located at three topographic positions (low, medium and high) and on two slope aspects (north and south). Eight leaf and four stem functional traits, relating to the plants’ ability to avoid or tolerate water and temperature stress, were measured. Community-level functional traits were strongly affected by topographic position while only a weak signal was detected by the slope aspect. Contrary to our expectations, attributes associated with drought tolerance predominated on the lower topographic positions of the slopes, (moister and warmer sites), while on the upper parts with drier soil, but cooler air, attributes associated with water stress avoidance dominated. In addition, variation in the dominance of leaf pulvini and trichomes along the topographic gradient suggests environmental filtering by elevated air temperatures and water stress, respectively. Overall, our results suggest that the upper topographic positions that generate a shorter and more fluctuating water-availability window, favor readily-deciduous plants with high levels of water storage in their tissues, traits allowing for a rapid avoid of water stress, whereas on the lower topographic positions, where the soil remains moist for longer periods of time, tardily-deciduous species thrive with dense, low-water content tissues, attributes that are associated with physiological tolerance to drought.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
de Soyza, A.G.; Kay, L.E.; Gutschick, V.P.
In growth chamber experiments the authors compared the water-use efficiency (WUE) and drought tolerance (DT - retention of dry mass vegetative yield when droughted) of the drought intolerant common tomato, L. esculentum and the ostensibly drought tolerant tomato, L. pennellii. Drought treatment was imposed as two severe episodes of drought, each episode lasting until all leaves on the plant were silted, with a period of recovery between treatments. They measured up to 20 performance attributes to WUE and DT, including: root:shoot ratio, leaf internal CO2/ambient CO2, {delta}{sup 13}C, leaf photosynthetic rate, specific leaf mass, leaf water potential, leaf osmotic potential,more » and stomatal density. Water-use efficiency is negatively correlated with drought tolerance; drought tolerance is positively correlated with plants' ability to increase WUE under stress. Few other attributes are correlated with drought tolerance, and some are conspicuous by their absence. They find evidence for substantial genetic linkage among attributes that confer drought tolerance; and interplant rankings in drought tolerance depend strongly upon the type of drought stress experienced (episodic vs. continuous).« less
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Network Candidate Genes in Breeding for Drought Tolerant Crops
Krannich, Christoph Tim; Maletzki, Lisa; Kurowsky, Christina; Horn, Renate
2015-01-01
Climate change leading to increased periods of low water availability as well as increasing demands for food in the coming years makes breeding for drought tolerant crops a high priority. Plants have developed diverse strategies and mechanisms to survive drought stress. However, most of these represent drought escape or avoidance strategies like early flowering or low stomatal conductance that are not applicable in breeding for crops with high yields under drought conditions. Even though a great deal of research is ongoing, especially in cereals, in this regard, not all mechanisms involved in drought tolerance are yet understood. The identification of candidate genes for drought tolerance that have a high potential to be used for breeding drought tolerant crops represents a challenge. Breeding for drought tolerant crops has to focus on acceptable yields under water-limited conditions and not on survival. However, as more and more knowledge about the complex networks and the cross talk during drought is available, more options are revealed. In addition, it has to be considered that conditioning a crop for drought tolerance might require the production of metabolites and might cost the plants energy and resources that cannot be used in terms of yield. Recent research indicates that yield penalty exists and efficient breeding for drought tolerant crops with acceptable yields under well-watered and drought conditions might require uncoupling yield penalty from drought tolerance. PMID:26193269
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Network Candidate Genes in Breeding for Drought Tolerant Crops.
Krannich, Christoph Tim; Maletzki, Lisa; Kurowsky, Christina; Horn, Renate
2015-07-17
Climate change leading to increased periods of low water availability as well as increasing demands for food in the coming years makes breeding for drought tolerant crops a high priority. Plants have developed diverse strategies and mechanisms to survive drought stress. However, most of these represent drought escape or avoidance strategies like early flowering or low stomatal conductance that are not applicable in breeding for crops with high yields under drought conditions. Even though a great deal of research is ongoing, especially in cereals, in this regard, not all mechanisms involved in drought tolerance are yet understood. The identification of candidate genes for drought tolerance that have a high potential to be used for breeding drought tolerant crops represents a challenge. Breeding for drought tolerant crops has to focus on acceptable yields under water-limited conditions and not on survival. However, as more and more knowledge about the complex networks and the cross talk during drought is available, more options are revealed. In addition, it has to be considered that conditioning a crop for drought tolerance might require the production of metabolites and might cost the plants energy and resources that cannot be used in terms of yield. Recent research indicates that yield penalty exists and efficient breeding for drought tolerant crops with acceptable yields under well-watered and drought conditions might require uncoupling yield penalty from drought tolerance.
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Shi, Haitao; Wang, Yanping; Cheng, Zhangmin; Ye, Tiantian; Chan, Zhulong
2012-01-01
Bermudagrass (Cynodon dactylon) is a widely used warm-season turfgrass and one of the most drought tolerant species. Dissecting the natural variation in drought tolerance and physiological responses will bring us powerful basis and novel insight for plant breeding. In the present study, we evaluated the natural variation of drought tolerance among nine bermudagrass varieties by measuring physiological responses after drought stress treatment through withholding water. Three groups differing in drought tolerance were identified, including two tolerant, five moderately tolerant and two susceptible varieties. Under drought stress condition, drought sensitive variety (Yukon) showed relative higher water loss, more severe cell membrane damage (EL), and more accumulation of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA), while drought tolerant variety (Tifgreen) exhibited significantly higher antioxidant enzymes activities. Further results indicated that drought induced cell injury in different varieties (Yukon, SR9554 and Tifgreen) exhibited liner correlation with leaf water content (LWC), H₂O₂ content, MDA content and antioxidant enzyme activities. Additionally, Tifgreen plants had significantly higher levels of osmolytes (proline level and soluble sugars) when compared with Yukon and SR9554 under drought stress condition. Taken together, our results indicated that natural variation of drought stress tolerance in bermudagrass varieties might be largely related to the induced changes of water status, osmolyte accumulation and antioxidant defense system.
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Kim, Tae-Heon; Hur, Yeon-Jae; Han, Sang-Ik; Cho, Jun-Hyun; Kim, Kyung-Min; Lee, Jong-Hee; Song, You-Chun; Kwon, Yeong-Up; Shin, Dongjin
2017-03-01
Drought is an important limiting factor for rice production, but the genetic mechanisms of drought tolerance is poorly understood. Here, we screened 218 rice varieties to identify 32 drought-tolerant varieties. The variety Samgang exhibited strong drought tolerance and stable yield in rain-fed conditions and was selected for further study. To identify QTLs for drought tolerance, we examined visual drought tolerance (VDT) and relative water content (RWC) phenotypes in a doubled haploid (DH) population of 101 individuals derived from a cross between Samgang and Nagdong (a drought-sensitive variety). Three QTLs from Samgang were identified for VDT and explained 41.8% of the phenotypic variance. In particular, qVDT11 contributed 20.3% of the phenotypic variance for RWC. To determine QTL effects on drought tolerance in rain-fed paddy conditions, seven DH lines were selected according to the number of QTLs they contained. Of the drought-tolerance-associated QTLs, qVDT2 and qVDT6 did not affect tiller formation, but qVDT11 increased tiller number. Tiller formation was most stable when qVDT2 and qVDT11 were combined. DH lines with both of these drought-tolerance-associated QTLs exhibited the most stable tiller formation. Together, these results suggest that qVDT11 is important for drought tolerance and stable tiller formation in rain-fed paddy fields. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
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Nguyen, Quang Thien; Hoang, Xuan Lan Thi; Thao, Nguyen Phuong; Tran, Lam-Son Phan
2014-01-01
Drought is one of the greatest constraints to soybean production in many countries, including Vietnam. Although a wide variety of the newly produced cultivars have been produced recently in Vietnam through classical breeding to cope with water shortage, little knowledge of their molecular and physiological responses to drought has been discovered. This study was conducted to quickly evaluate drought tolerance of thirteen local soybean cultivars for selection of the best drought-tolerant cultivars for further field test. Differences in drought tolerance of cultivars were assessed by root and shoot lengths, relative water content, and drought-tolerant index under both normal and drought conditions. Our data demonstrated that DT51 is the strongest drought-tolerant genotype among all the tested cultivars, while the highest drought-sensitive phenotype was observed with MTD720. Thus, DT51 could be subjected to further yield tests in the field prior to suggesting it for use in production. Due to their contrasting drought-tolerant phenotypes, DT51 and MTD720 provide excellent genetic resources for further studies underlying mechanisms regulating drought responses and gene discovery. Our results provide vital information to support the effort of molecular breeding and genetic engineering to improve drought tolerance of soybean. PMID:24804248
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USDA-ARS?s Scientific Manuscript database
Cotton productivity is affected by water deficit, and little is known about the molecular basis of drought tolerance in cotton. In this study, microarray analysis was conducted to identify drought-responsive genes in the third topmost leaves of the field-grown drought-tolerant cotton (Gossypium hirs...
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Drought Tolerance in Modern and Wild Wheat
Budak, Hikmet; Kantar, Melda; Yucebilgili Kurtoglu, Kuaybe
2013-01-01
The genus Triticum includes bread (Triticum aestivum) and durum wheat (Triticum durum) and constitutes a major source for human food consumption. Drought is currently the leading threat on world's food supply, limiting crop yield, and is complicated since drought tolerance is a quantitative trait with a complex phenotype affected by the plant's developmental stage. Drought tolerance is crucial to stabilize and increase food production since domestication has limited the genetic diversity of crops including wild wheat, leading to cultivated species, adapted to artificial environments, and lost tolerance to drought stress. Improvement for drought tolerance can be achieved by the introduction of drought-grelated genes and QTLs to modern wheat cultivars. Therefore, identification of candidate molecules or loci involved in drought tolerance is necessary, which is undertaken by “omics” studies and QTL mapping. In this sense, wild counterparts of modern varieties, specifically wild emmer wheat (T. dicoccoides), which are highly tolerant to drought, hold a great potential. Prior to their introgression to modern wheat cultivars, drought related candidate genes are first characterized at the molecular level, and their function is confirmed via transgenic studies. After integration of the tolerance loci, specific environment targeted field trials are performed coupled with extensive analysis of morphological and physiological characteristics of developed cultivars, to assess their performance under drought conditions and their possible contributions to yield in certain regions. This paper focuses on recent advances on drought related gene/QTL identification, studies on drought related molecular pathways, and current efforts on improvement of wheat cultivars for drought tolerance. PMID:23766697
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Vitali, Valentina; Büntgen, Ulf; Bauhus, Jürgen
2017-12-01
Improving our understanding of the potential of forest adaptation is an urgent task in the light of predicted climate change. Long-term alternatives for susceptible yet economically important tree species such as Norway spruce (Picea abies) are required, if the frequency and intensity of summer droughts will continue to increase. Although Silver fir (Abies alba) and Douglas fir (Pseudotsuga menziesii) have both been described as drought-tolerant species, our understanding of their growth responses to drought extremes is still limited. Here, we use a dendroecological approach to assess the resistance, resilience, and recovery of these important central Europe to conifer species the exceptional droughts in 1976 and 2003. A total of 270 trees per species were sampled in 18 managed mixed-species stands along an altitudinal gradient (400-1200 m a.s.l.) at the western slopes of the southern and central Black Forest in southwest Germany. While radial growth in all species responded similarly to the 1976 drought, Norway spruce was least resistant and resilient to the 2003 summer drought. Silver fir showed the overall highest resistance to drought, similarly to Douglas fir, which exhibited the widest growth rings. Silver fir trees from lower elevations were more drought prone than trees at higher elevations. Douglas fir and Norway spruce, however, revealed lower drought resilience at higher altitudes. Although the 1976 and 2003 drought extremes were quite different, Douglas fir maintained consistently the highest radial growth. Although our study did not examine population-level responses, it clearly indicates that Silver fir and Douglas fir are generally more resistant and resilient to previous drought extremes and are therefore suitable alternatives to Norway spruce; Silver fir more so at higher altitudes. Cultivating these species instead of Norway spruce will contribute to maintaining a high level of productivity across many Central European mountain forests under future climate change. © 2017 John Wiley & Sons Ltd.
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The olive tree: a paradigm for drought tolerance in Mediterranean climates
NASA Astrophysics Data System (ADS)
Sofo, A.; Manfreda, S.; Fiorentino, M.; Dichio, B.; Xiloyannis, C.
2008-02-01
Olive trees (Olea europaea L.) are commonly grown in the Mediterranean basin where prolonged droughts may occur during the vegetative period. This species has developed a series of physiological mechanisms, that can be observed in several plants of the Mediterranean macchia, to tolerate drought stress and grow under adverse climatic conditions. These mechanisms have been investigated through an experimental campaign carried out over both irrigated and drought-stressed plants in order to comprehend the plant response under stressed conditions and its ability to recover. Experimental results show that olive plants subjected to water deficit lower the water content and water potentials of their tissues, establishing a particularly high potential gradient between leaves and roots, and stop canopy growth but not photosynthetic activity and transpiration. This allows the continuous production of assimilates as well as their accumulation in the various plant parts, so creating a higher root/leaf ratio if compared to well-watered plants. Active and passive osmotic adjustment due to the accumulation of carbohydrates (in particular mannitol and glucose), proline and other osmolytes have key roles in maintaining cell turgor and leaf activities. At severe drought-stress levels, the non-stomatal component of photosynthesis is inhibited and a light-dependent inactivation of the photosystem II occurs. Finally, the activities of some antioxidant enzymes involved in the scavenging of activated oxygen species and in other biochemical pathways increase during a period of drought. The present paper provides an overview of the driving mechanisms adopted by olive trees to face drought stress with the aim of better understanding plant-soil interactions.
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The olive tree: a paradigm for drought tolerance in Mediterranean climates
NASA Astrophysics Data System (ADS)
Sofo, A.; Manfreda, S.; Dichio, B.; Fiorentino, M.; Xiloyannis, C.
2007-09-01
Olive tree (Olea europaea L.) is commonly grown in the Mediterranean basin where prolonged droughts may occur during the vegetative period. This species has developed a series of physiological mechanisms to tolerate drought stress and grow under adverse climatic conditions that can be observed in numerous plants of the Mediterranean macchia. These mechanisms have been investigated through an experimental campaign carried out over both irrigated and drought-stressed plants in order to comprehend the plant response under stressed conditions and its ability to recover. Experimental results show that olive plants subjected to water deficit lower the water content and water potentials of their tissues, establishing a particularly high potential gradient between leaves and roots, and stop canopy growth but not photosynthetic activity and transpiration. This allows the continuous production of assimilates as well as their accumulation in the various plant parts, so creating a higher root/leaf ratio if compared to well-watered plants. Active and passive osmotic adjustment due to the accumulation of sugars (in particular mannitol and glucose), proline and other osmolytes has a key role in maintaining cell turgor and leaf activities. At severe drought-stress levels, the non-stomatal component of photosynthesis is inhibited and a light-dependent inactivation of the photosystem II occurs. Finally, the activities of some antioxidant enzymes involved in the scavenging of activated oxygen species and in other biochemical pathways, increase during a period of drought. The present paper provides an overview of the driving mechanisms adopted by olive trees to face drought stress with the aim of better understand plant-soil interactions.
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Monneveux, Philippe; Ramírez, David A; Pino, María-Teresa
2013-05-01
Drought tolerance is a complex trait of increasing importance in potato. Our knowledge is summarized concerning drought tolerance and water use efficiency in this crop. We describe the effects of water restriction on physiological characteristics, examine the main traits involved, report the attempts to improve drought tolerance through in vitro screening and marker assisted selection, list the main genes involved and analyze the potential interest of native and wild potatoes to improve drought tolerance. Drought tolerance has received more attention in cereals than in potato. The review compares these crops for indirect selection methods available for assessment of drought tolerance related traits, use of genetic resources, progress in genomics, application of water saving techniques and availability of models to anticipate the effects of climate change on yield. It is concluded that drought tolerance improvement in potato could greatly benefit from the transfer of research achievements in cereals. Several promising research directions are presented, such as the use of fluorescence, reflectance, color and thermal imaging and stable isotope techniques to assess drought tolerance related traits, the application of the partial root-zone drying technique to improve efficiency of water supply and the exploitation of stressful memory to enhance hardiness. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.
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Cheng, Zhangmin; Ye, Tiantian; Chan, Zhulong
2012-01-01
Bermudagrass (Cynodon dactylon) is a widely used warm-season turfgrass and one of the most drought tolerant species. Dissecting the natural variation in drought tolerance and physiological responses will bring us powerful basis and novel insight for plant breeding. In the present study, we evaluated the natural variation of drought tolerance among nine bermudagrass varieties by measuring physiological responses after drought stress treatment through withholding water. Three groups differing in drought tolerance were identified, including two tolerant, five moderately tolerant and two susceptible varieties. Under drought stress condition, drought sensitive variety (Yukon) showed relative higher water loss, more severe cell membrane damage (EL), and more accumulation of hydrogen peroxide (H2O2) and malondialdehyde (MDA), while drought tolerant variety (Tifgreen) exhibited significantly higher antioxidant enzymes activities. Further results indicated that drought induced cell injury in different varieties (Yukon, SR9554 and Tifgreen) exhibited liner correlation with leaf water content (LWC), H2O2 content, MDA content and antioxidant enzyme activities. Additionally, Tifgreen plants had significantly higher levels of osmolytes (proline level and soluble sugars) when compared with Yukon and SR9554 under drought stress condition. Taken together, our results indicated that natural variation of drought stress tolerance in bermudagrass varieties might be largely related to the induced changes of water status, osmolyte accumulation and antioxidant defense system. PMID:23285294
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Biju, Sajitha; Fuentes, Sigfredo; Gupta, Dorin
2018-06-01
Lentil (Lens culinaris, Medik.) is an important legume crop, which often experience drought stress especially at the flowering and grain filling phenological stages. The availability of efficient and robust screening tools based on relevant non-destructive quantifiable traits would facilitate research on crop improvement for drought tolerance. The objective of this study was to evaluate the drought tolerance of 37 lentil genotypes using infrared thermal imaging (IRTI), drought tolerance parameters and multivariate data analysis. Potted plants were kept in a completely randomized design in a growth chamber with five replicates. Plants were subjected to three different drought treatments: 100, 50 and 20% of field capacity at the onset of reproductive period. The relative drought stress tolerance was determined based on a set of morpho-physiological parameters including non-destructive measures based on IRTI, such as: canopy temperature (Tc), canopy temperature depression (CTD) and crop water stress index (CWSI) during the growing period and destructive measures at harvest, such as: dry root-shoot ratio (RS ratio), relative water content (RWC) and harvest index (HI). The drought tolerance indices used were drought susceptibility index (DSI) and drought tolerance efficiency (DTE). Results showed that drought stress treatments significantly reduced the RWC, HI, CTD and DSI, whereas, the values of Tc, CWSI, RS ratio and DTE significantly increased for all the genotypes. The cluster analysis from morpho-physiological parameters clustered genotypes in three distinctive groups as per the level of drought stress tolerance. The genotypes with higher values of RS ratio, RWC, HI, DTE and CTD and lower values of DSI, Tc and CWSI were identified as drought-tolerant genotypes. Based on this preliminary screening, the genotypes Digger, Cumra, Indianhead, ILL 5588, ILL 6002 and ILL 5582 were identified as promising drought-tolerant genotypes. It can be concluded that the IRTI analysis is a high-throughput constructive screening tool along with RS ratio, RWC, HI and other drought tolerance indices to define the drought stress tolerance variability within lentil plants. These results provide a foundation for future research directed at identifying powerful drought assessment traits using rapid and non-destructive techniques, such as IRTI along with the yield traits, and understanding the biochemical and molecular mechanisms underlying lentil tolerance to drought stress. Copyright © 2018 Elsevier Masson SAS. All rights reserved.
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Role of gamma-oryzanol in drought-tolerant and susceptible cultivars of rice (Oryza sativa L.).
Kumar, M S Sujith; Dahuja, Anil; Rai, R D; Walia, Suresh; Tyagi, Aruna
2014-02-01
Drought-tolerant cultivars and their phytochemical composition, which has a role in providing drought tolerance are gaining importance. In this study, rice bran oil and semi-purified oryzanol (SPO) obtained from five rice (Oryza sativa L.) cultivars, namely P1401 and PB1 (drought-susceptible) and N22, PNR381 and APO (drought-tolerant) were analyzed for the gamma-oryzanol content, an antioxidant present in considerable amount in the rice bran. The higher level of gamma-oryzanol and its antioxidant activity was observed in drought-tolerant cultivars (N22, PNR381 and APO) as compared to drought-susceptible (PB1 and P1401), suggesting the role of gamma-oryzanol in drought tolerance, as antioxidants are known to play an important role by scavenging free radicals. The total antioxidant activity of gamma-oryzanol might be attributed to 24-methylene cycloartanyl ferulate, a major component of gamma-oryzanol. By enhancing the level of active oryzanol components identified in this study by genetic and molecular means could impart increased drought tolerance.
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Vikram, Prashant; Swamy, B. P. Mallikarjuna; Dixit, Shalabh; Singh, Renu; Singh, Bikram P.; Miro, Berta; Kohli, Ajay; Henry, Amelia; Singh, N. K.; Kumar, Arvind
2015-01-01
Green Revolution (GR) rice varieties are high yielding but typically drought sensitive. This is partly due to the tight linkage between the loci governing plant height and drought tolerance. This linkage is illustrated here through characterization of qDTY1.1, a QTL for grain yield under drought that co-segregates with the GR gene sd1 for semi-dwarf plant height. We report that the loss of the qDTY1.1 allele during the GR was due to its tight linkage in repulsion with the sd1 allele. Other drought-yield QTLs (qDTY) also showed tight linkage with traits rejected in GR varieties. Genetic diversity analysis for 11 different qDTY regions grouped GR varieties separately from traditional drought-tolerant varieties, and showed lower frequency of drought tolerance alleles. The increased understanding and breaking of the linkage between drought tolerance and undesirable traits has led to the development of high-yielding drought-tolerant dwarf lines with positive qDTY alleles and provides new hope for extending the benefits of the GR to drought-prone rice-growing regions. PMID:26458744
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USDA-ARS?s Scientific Manuscript database
Drought tolerance is a complex trait that is governed by multiple genes. To identify the potential candidate genes, comparative analysis of drought stress-responsive transcriptome between drought-tolerant (Triticum aestivum Cv. C306) and drought-sensitive (Triticum aestivum Cv. WL711) genotypes was ...
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Mutava, Raymond N; Prince, Silvas Jebakumar K; Syed, Naeem Hasan; Song, Li; Valliyodan, Babu; Chen, Wei; Nguyen, Henry T
2015-01-01
Many sources of drought and flooding tolerance have been identified in soybean, however underlying molecular and physiological mechanisms are poorly understood. Therefore, it is important to illuminate different plant responses to these abiotic stresses and understand the mechanisms that confer tolerance. Towards this goal we used four contrasting soybean (Glycine max) genotypes (PI 567690--drought tolerant, Pana--drought susceptible, PI 408105A--flooding tolerant, S99-2281--flooding susceptible) grown under greenhouse conditions and compared genotypic responses to drought and flooding at the physiological, biochemical, and cellular level. We also quantified these variations and tried to infer their role in drought and flooding tolerance in soybean. Our results revealed that different mechanisms contribute to reduction in net photosynthesis under drought and flooding stress. Under drought stress, ABA and stomatal conductance are responsible for reduced photosynthetic rate; while under flooding stress, accumulation of starch granules played a major role. Drought tolerant genotypes PI 567690 and PI 408105A had higher plastoglobule numbers than the susceptible Pana and S99-2281. Drought stress increased the number and size of plastoglobules in most of the genotypes pointing to a possible role in stress tolerance. Interestingly, there were seven fibrillin proteins localized within the plastoglobules that were up-regulated in the drought and flooding tolerant genotypes PI 567690 and PI 408105A, respectively, but down-regulated in the drought susceptible genotype Pana. These results suggest a potential role of Fibrillin proteins, FBN1a, 1b and 7a in soybean response to drought and flooding stress. Copyright © 2014 Elsevier Masson SAS. All rights reserved.
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Tang, Sha; Li, Lin; Wang, Yongqiang; Chen, Qiannan; Zhang, Wenying; Jia, Guanqing; Zhi, Hui; Zhao, Baohua; Diao, Xianmin
2017-08-30
Understanding drought-tolerance mechanisms and identifying genetic dominance are important for crop improvement. Setaria italica, which is extremely drought-tolerant, has been regarded as a model plant for studying stress biology. Moreover, different genotypes of S. italica have evolved various drought-tolerance/avoidance mechanisms that should be elucidated. Physiological and transcriptomic comparisons between drought-tolerant S. italica cultivar 'Yugu1' and drought-sensitive 'An04' were conducted. 'An04' had higher yields and more efficient photosystem activities than 'Yugu1' under well-watered conditions, and this was accompanied by positive brassinosteroid regulatory actions. However, 'An04's growth advantage was severely repressed by drought, while 'Yugu1' maintained normal growth under a water deficiency. High-throughput sequencing suggested that the S. italica transcriptome was severely remodelled by genotype × environment interactions. Expression profiles of genes related to phytohormone metabolism and signalling, transcription factors, detoxification, and other stress-related proteins were characterised, revealing genotype-dependent and -independent drought responses in different S. italica genotypes. Combining our data with drought-tolerance-related QTLs, we identified 20 candidate genes that contributed to germination and early seedling' drought tolerance in S. italica. Our analysis provides a comprehensive picture of how different S. italica genotypes respond to drought, and may be used for the genetic improvement of drought tolerance in Poaceae crops.
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Wang, Hongwei; Xin, Haibo; Yang, Xiaohong; Yan, Jianbing; Li, Jiansheng; Tran, Lam-Son Phan; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko; Qin, Feng
2013-01-01
The worldwide production of maize (Zea mays L.) is frequently impacted by water scarcity and as a result, increased drought tolerance is a priority target in maize breeding programs. While DREB transcription factors have been demonstrated to play a central role in desiccation tolerance, whether or not natural sequence variations in these genes are associated with the phenotypic variability of this trait is largely unknown. In the present study, eighteen ZmDREB genes present in the maize B73 genome were cloned and systematically analyzed to determine their phylogenetic relationship, synteny with rice, maize and sorghum genomes; pattern of drought-responsive gene expression, and protein transactivation activity. Importantly, the association between the nucleic acid variation of each ZmDREB gene with drought tolerance was evaluated using a diverse population of maize consisting of 368 varieties from tropical and temperate regions. A significant association between the genetic variation of ZmDREB2.7 and drought tolerance at seedling stage was identified. Further analysis found that the DNA polymorphisms in the promoter region of ZmDREB2.7, but not the protein coding region itself, was associated with different levels of drought tolerance among maize varieties, likely due to distinct patterns of gene expression in response to drought stress. In vitro, protein-DNA binding assay demonstrated that ZmDREB2.7 protein could specifically interact with the target DNA sequences. The transgenic Arabidopsis overexpressing ZmDREB2.7 displayed enhanced tolerance to drought stress. Moreover, a favorable allele of ZmDREB2.7, identified in the drought-tolerant maize varieties, was effective in imparting plant tolerance to drought stress. Based upon these findings, we conclude that natural variation in the promoter of ZmDREB2.7 contributes to maize drought tolerance, and that the gene and its favorable allele may be an important genetic resource for the genetic improvement of drought tolerance in maize. PMID:24086146
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Gaviria, Julian; Engelbrecht, Bettina M. J.
2015-01-01
Tree species distributions associated with rainfall are among the most prominent patterns in tropical forests. Understanding the mechanisms shaping these patterns is important to project impacts of global climate change on tree distributions and diversity in the tropics. Beside direct effects of water availability, additional factors co-varying with rainfall have been hypothesized to play an important role, including pest pressure and light availability. While low water availability is expected to exclude drought-intolerant wet forest species from drier forests (physiological tolerance hypothesis), high pest pressure or low light availability are hypothesized to exclude dry forest species from wetter forests (pest pressure gradient and light availability hypothesis, respectively). To test these hypotheses at the seed-to-seedling transition, the potentially most critical stage for species discrimination, we conducted a reciprocal transplant experiment combined with a pest exclosure treatment at a wet and a dry forest site in Panama with seeds of 26 species with contrasting origin. Establishment success after one year did not reflect species distribution patterns. However, in the wet forest, wet origin species had a home advantage over dry forest species through higher growth rates. At the same time, drought limited survival of wet origin species in the dry forest, supporting the physiological tolerance hypothesis. Together these processes sort species over longer time frames, and exclude species outside their respective home range. Although we found pronounced effects of pests and some effects of light availability on the seedlings, they did not corroborate the pest pressure nor light availability hypotheses at the seed-to-seedling transition. Our results underline that changes in water availability due to climate change will have direct consequences on tree regeneration and distributions along tropical rainfall gradients, while indirect effects of light and pests are less important. PMID:26619138
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Hayano-Kanashiro, Corina; Calderón-Vázquez, Carlos; Ibarra-Laclette, Enrique; Herrera-Estrella, Luis; Simpson, June
2009-01-01
Background Drought is one of the major constraints for plant productivity worldwide. Different mechanisms of drought-tolerance have been reported for several plant species including maize. However, the differences in global gene expression between drought-tolerant and susceptible genotypes and their relationship to physiological adaptations to drought are largely unknown. The study of the differences in global gene expression between tolerant and susceptible genotypes could provide important information to design more efficient breeding programs to produce maize varieties better adapted to water limiting conditions. Methodology/Principal Findings Changes in physiological responses and gene expression patterns were studied under drought stress and recovery in three Mexican maize landraces which included two drought tolerant (Cajete criollo and Michoacán 21) and one susceptible (85-2) genotypes. Photosynthesis, stomatal conductance, soil and leaf water potentials were monitored throughout the experiment and microarray analysis was carried out on transcripts obtained at 10 and 17 days following application of stress and after recovery irrigation. The two tolerant genotypes show more drastic changes in global gene expression which correlate with different physiological mechanisms of adaptation to drought. Differences in the kinetics and number of up- and down-regulated genes were observed between the tolerant and susceptible maize genotypes, as well as differences between the two tolerant genotypes. Interestingly, the most dramatic differences between the tolerant and susceptible genotypes were observed during recovery irrigation, suggesting that the tolerant genotypes activate mechanisms that allow more efficient recovery after a severe drought. Conclusions/Significance A correlation between levels of photosynthesis and transcription under stress was observed and differences in the number, type and expression levels of transcription factor families were also identified under drought and recovery between the three maize landraces. Gene expression analysis suggests that the drought tolerant landraces have a greater capacity to rapidly modulate more genes under drought and recovery in comparison to the susceptible landrace. Modulation of a greater number of differentially expressed genes of different TF gene families is an important characteristic of the tolerant genotypes. Finally, important differences were also noted between the tolerant landraces that underlie different mechanisms of achieving tolerance. PMID:19888455
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Tree genetics defines fungal partner communities that may confer drought tolerance.
Gehring, Catherine A; Sthultz, Christopher M; Flores-Rentería, Lluvia; Whipple, Amy V; Whitham, Thomas G
2017-10-17
Plant genetic variation and soil microorganisms are individually known to influence plant responses to climate change, but the interactive effects of these two factors are largely unknown. Using long-term observational studies in the field and common garden and greenhouse experiments of a foundation tree species ( Pinus edulis ) and its mutualistic ectomycorrhizal fungal (EMF) associates, we show that EMF community composition is under strong plant genetic control. Seedlings acquire the EMF community of their seed source trees (drought tolerant vs. drought intolerant), even when exposed to inoculum from the alternate tree type. Drought-tolerant trees had 25% higher growth and a third the mortality of drought-intolerant trees over the course of 10 y of drought in the wild, traits that were also observed in their seedlings in a common garden. Inoculation experiments show that EMF communities are critical to drought tolerance. Drought-tolerant and drought-intolerant seedlings grew similarly when provided sterile EMF inoculum, but drought-tolerant seedlings grew 25% larger than drought-intolerant seedlings under dry conditions when each seedling type developed its distinct EMF community. This demonstration that particular combinations of plant genotype and mutualistic EMF communities improve the survival and growth of trees with drought is especially important, given the vulnerability of forests around the world to the warming and drying conditions predicted for the future.
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Recent progress in drought and salt tolerance studies in Brassica crops
Zhang, Xuekun; Lu, Guangyuan; Long, Weihua; Zou, Xiling; Li, Feng; Nishio, Takeshi
2014-01-01
Water deficit imposed by either drought or salinity brings about severe growth retardation and yield loss of crops. Since Brassica crops are important contributors to total oilseed production, it is urgently needed to develop tolerant cultivars to ensure yields under such adverse conditions. There are various physiochemical mechanisms for dealing with drought and salinity in plants at different developmental stages. Accordingly, different indicators of tolerance to drought or salinity at the germination, seedling, flowering and mature stages have been developed and used for germplasm screening and selection in breeding practices. Classical genetic and modern genomic approaches coupled with precise phenotyping have boosted the unravelling of genes and metabolic pathways conferring drought or salt tolerance in crops. QTL mapping of drought and salt tolerance has provided several dozen target QTLs in Brassica and the closely related Arabidopsis. Many drought- or salt-tolerant genes have also been isolated, some of which have been confirmed to have great potential for genetic improvement of plant tolerance. It has been suggested that molecular breeding approaches, such as marker-assisted selection and gene transformation, that will enhance oil product security under a changing climate be integrated in the development of drought- and salt-tolerant Brassica crops. PMID:24987291
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Taïbi, Khaled; del Campo, Antonio D.; Vilagrosa, Alberto; Bellés, José M.; López-Gresa, María Pilar; Pla, Davinia; Calvete, Juan J.; López-Nicolás, José M.; Mulet, José M.
2017-01-01
Drought is one of the main constraints determining forest species growth, survival and productivity, and therefore one of the main limitations for reforestation or afforestation. The aim of this study is to characterize the drought response at the physiological and molecular level of different Pinus halepensis (common name Aleppo pine) seed sources, previously characterized in field trials as drought-sensitive or drought-tolerant. This approach aims to identify different traits capable of predicting the ability of formerly uncharacterized seedlings to cope with drought stress. Gas-exchange, water potential, photosynthetic pigments, soluble sugars, free amino acids, glutathione and proteomic analyses were carried out on control and drought-stressed seedlings in greenhouse conditions. Gas-exchange determinations were also assessed in field-planted seedlings in order to validate the greenhouse experimental conditions. Drought-tolerant seed sources presented higher values of photosynthetic rates, water use efficiency, photosynthetic pigments and soluble carbohydrates concentrations. We observed the same pattern of variation of photosynthesis rate and maximal efficiency of PSII in field. Interestingly drought-tolerant seed sources exhibited increased levels of glutathione, methionine and cysteine. The proteomic profile of drought tolerant seedlings identified two heat shock proteins and an enzyme related to methionine biosynthesis that were not present in drought sensitive seedlings, pointing to the synthesis of sulfur amino acids as a limiting factor for drought tolerance in Pinus halepensis. Our results established physiological and molecular traits useful as distinctive markers to predict drought tolerance in Pinus halepensis provenances that could be reliably used in reforestation programs in drought prone areas. PMID:28791030
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Taïbi, Khaled; Del Campo, Antonio D; Vilagrosa, Alberto; Bellés, José M; López-Gresa, María Pilar; Pla, Davinia; Calvete, Juan J; López-Nicolás, José M; Mulet, José M
2017-01-01
Drought is one of the main constraints determining forest species growth, survival and productivity, and therefore one of the main limitations for reforestation or afforestation. The aim of this study is to characterize the drought response at the physiological and molecular level of different Pinus halepensis (common name Aleppo pine) seed sources, previously characterized in field trials as drought-sensitive or drought-tolerant. This approach aims to identify different traits capable of predicting the ability of formerly uncharacterized seedlings to cope with drought stress. Gas-exchange, water potential, photosynthetic pigments, soluble sugars, free amino acids, glutathione and proteomic analyses were carried out on control and drought-stressed seedlings in greenhouse conditions. Gas-exchange determinations were also assessed in field-planted seedlings in order to validate the greenhouse experimental conditions. Drought-tolerant seed sources presented higher values of photosynthetic rates, water use efficiency, photosynthetic pigments and soluble carbohydrates concentrations. We observed the same pattern of variation of photosynthesis rate and maximal efficiency of PSII in field. Interestingly drought-tolerant seed sources exhibited increased levels of glutathione, methionine and cysteine. The proteomic profile of drought tolerant seedlings identified two heat shock proteins and an enzyme related to methionine biosynthesis that were not present in drought sensitive seedlings, pointing to the synthesis of sulfur amino acids as a limiting factor for drought tolerance in Pinus halepensis . Our results established physiological and molecular traits useful as distinctive markers to predict drought tolerance in Pinus halepensis provenances that could be reliably used in reforestation programs in drought prone areas.
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Ha, Chien Van; Le, Dung Tien; Nishiyama, Rie; Watanabe, Yasuko; Tran, Uyen Thi; Dong, Nguyen Van; Tran, Lam-Son Phan
2013-01-01
Soybean (Glycine max) productivity is adversely affected by drought stress worldwide, including Vietnam. In the last few years, we have made a great effort in the development of drought-tolerant soybean cultivars by breeding and/or radiation-induced mutagenesis. One of the newly developed cultivars, the DT2008, showed enhanced drought tolerance and stable yield in the field conditions. The purpose of this study was to compare the drought-tolerant phenotype of DT2008 and Williams 82 (W82) by assessing their water loss and growth rate under dehydration and/or drought stress conditions as a means to provide genetic resources for further comparative and functional genomics. We found that DT2008 had reduced water loss under both dehydration and drought stresses in comparison with W82. The examination of root and shoot growths of DT2008 and W82 under both normal and drought conditions indicated that DT2008 maintains a better shoot and root growth rates than W82 under both two growth conditions. These results together suggest that DT2008 has better drought tolerance degree than W82. Our results open the way for further comparison of DT2008 and W82 at molecular levels by advanced omic approaches to identify mutation(s) involved in the enhancement of drought tolerance of DT2008, contributing to our understanding of drought tolerance mechanisms in soybean. Mutation(s) identified are potential candidates for genetic engineering of elite soybean varieties to improve drought tolerance and biomass. PMID:23509774
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Drought and submergence tolerance in plants
DOE Office of Scientific and Technical Information (OSTI.GOV)
Du, Hewei; Zhou, Yufan; Oksenberg, Nir
The invention provides methods of genetically modified plants to increase tolerance to drought and/or submergence. The invention additionally provides plants having increased drought and/or submergence tolerance engineered using such methods.
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Abid, Muhammad; Tian, Zhongwei; Ata-Ul-Karim, Syed Tahir; Liu, Yang; Cui, Yakun; Zahoor, Rizwan; Jiang, Dong; Dai, Tingbo
2016-09-01
Wheat crop endures a considerable penalty of yield reduction to escape the drought events during post-anthesis period. Drought priming under a pre-drought stress can enhance the crop potential to tolerate the subsequent drought stress by triggering a faster and stronger defense mechanism. Towards these understandings, a set of controlled moderate drought stress at 55-60% field capacity (FC) was developed to prime the plants of two wheat cultivars namely Luhan-7 (drought tolerant) and Yangmai-16 (drought sensitive) during tillering (Feekes 2 stage) and jointing (Feekes 6 stage), respectively. The comparative response of primed and non-primed plants, cultivars and priming stages was evaluated by applying a subsequent severe drought stress at 7 days after anthesis. The results showed that primed plants of both cultivars showed higher potential to tolerate the post-anthesis drought stress through improved leaf water potential, more chlorophyll, and ribulose-1, 5-bisphosphate carboxylase/oxygenase contents, enhanced photosynthesis, better photoprotection and efficient enzymatic antioxidant system leading to less yield reductions. The primed plants of Luhan-7 showed higher capability to adapt the drought stress events than Yangmai-16. The positive effects of drought priming to sustain higher grain yield were pronounced in plants primed at tillering than those primed at jointing. In consequence, upregulated functioning of photosynthetic apparatus and efficient enzymatic antioxidant activities in primed plants indicated their superior potential to alleviate a subsequently occurring drought stress, which contributed to lower yield reductions than non-primed plants. However, genotypic and priming stages differences in response to drought stress also contributed to affect the capability of primed plants to tolerate the post-anthesis drought stress conditions in wheat. Copyright © 2016. Published by Elsevier Masson SAS.
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Functional Genomics of Drought Tolerance in Bioenergy Crops
DOE Office of Scientific and Technical Information (OSTI.GOV)
Yin, Hengfu; Chen, Rick; Yang, Jun
2014-01-01
With the predicted trends in climate change, drought will increasingly impose a grand challenge to biomass production. Most of the bioenergy crops have some degree of drought susceptibility with low water-use efficiency (WUE). It is imperative to improve drought tolerance and WUE in bioenergy crops for sustainable biomass production in arid and semi-arid regions with minimal water input. Genetics and functional genomics can play a critical role in generating knowledge to inform and aid genetic improvement of drought tolerance in bioenergy crops. The molecular aspect of drought response has been extensively investigated in model plants like Arabidopsis, yet our understandingmore » of the molecular mechanisms underlying drought tolerance in bioenergy crops are limited. Crops exhibit various responses to drought stress depending on species and genotype. A rational strategy for studying drought tolerance in bioenergy crops is to translate the knowledge from model plants and pinpoint the unique features associated with individual species and genotypes. In this review, we summarize the general knowledge about drought responsive pathways in plants, with a focus on the identification of commonality and specialty in drought responsive mechanisms among different species and/or genotypes. We describe the genomic resources developed for bioenergy crops and discuss genetic and epigenetic regulation of drought responses. We also examine comparative and evolutionary genomics to leverage the ever-increasing genomics resources and provide new insights beyond what has been known from studies on individual species. Finally, we outline future exploration of drought tolerance using the emerging new technologies.« less
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Drought sensitivity predicts habitat size sensitivity in an aquatic ecosystem.
Amundrud, Sarah L; Srivastava, Diane S
2015-07-01
Species and trophic richness often increase with habitat size. Although many ecological processes have been evoked to explain both patterns, the environmental stress associated with small habitats has rarely been considered. We propose that larger habitats may be species rich simply because their environmental conditions are within the fundamental niche of more species; larger habitats may also have more trophic levels if traits of predators render them vulnerable to environmental stress. We test this hypothesis using the aquatic insect larvae in water-filled bromeliads. In bromeliads, the probability of desiccation is greatest in small plants. For the 10 most common bromeliad insect taxa, we ask whether differences in drought tolerance and regional abundances between taxa predict community and trophic composition over a gradient of bromeliad size. First, we used bromeliad survey data to calculate the mean habitat size of occurrence of each taxon. Comparing the observed mean habitat size of occurrence to that expected from random species assembly based on differences in their regional abundances allowed us to obtain habitat size sensitivity indices (as Z scores) for the various insect taxa. Second, we obtained drought sensitivity indices by subjecting individual insects to drought and measuring the effects on relative growth rates in a mesocosm experiment. We found that drought sensitivity strongly, predicts habitat size sensitivity in bromeliad insects. However, an increase in trophic richness with habitat size could not be explained by an increased sensitivity of predators to drought, but rather by sampling effects, as predators were rare compared to lower trophic levels. This finding suggests that physiological tolerance to environmental stress can be relevant in explaining the universal increase in species with habitat size.
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Mohammadi, Payam Pour; Moieni, Ahmad; Komatsu, Setsuko
2012-11-01
Rapeseed (Brassica napus L.), which is the third leading source of vegetable oil, is sensitive to drought stress during the early vegetative growth stage. To investigate the initial response of rapeseed to drought stress, changes in the protein expression profiles of drought-sensitive (RGS-003) and drought-tolerant lines (SLM-003), and their F1 hybrid, were analyzed using a proteomics approach. Seven-day-old rapeseed seedlings were treated with drought stress by restricting water for 7 days, and proteins were extracted from roots and separated by two-dimensional polyacrylamide gel electrophoresis. In the sensitive rapeseed line, 35 protein spots were differentially expressed under drought stress, and proteins related to metabolism, energy, disease/defense, and transport were decreased. In the tolerant line, 32 protein spots were differentially expressed under drought stress, and proteins involved in metabolism, disease/defense, and transport were increased, while energy-related proteins were decreased. Six protein spots in F1 hybrid were common among expressed proteins in the drought-sensitive and -tolerant lines. Notably, tubulin beta-2 and heat shock protein 70 were decreased in the drought-sensitive line and hybrid F1 plants, while jasmonate-inducible protein and 20S proteasome subunit PAF1 were increased in the F1 hybrids and drought-tolerant line. These results indicate that (1) V-type H(+) ATPase, plasma-membrane associated cation-binding protein, HSP 90, and elongation factor EF-2 have a role in the drought tolerance of rapeseed; (2) The decreased levels of heat shock protein 70 and tubulin beta-2 in the drought-sensitive and hybrid F1 lines might explain the reduced growth of these lines in drought conditions.
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Bang, Seung Woon; Lee, Dong-Keun; Jung, Harin; Chung, Pil Joong; Kim, Youn Shic; Choi, Yang Do; Suh, Joo-Won; Kim, Ju-Kon
2018-05-21
Drought stress seriously impacts on plant development and productivity. Improvement of drought tolerance without yield penalty is a great challenge in crop biotechnology. Here, we report that the rice (Oryza sativa) homeodomain-leucine zipper transcription factor gene, OsTF1L (Oryza sativa transcription factor 1-like), is a key regulator of drought tolerance mechanisms. Overexpression of the OsTF1L in rice significantly increased drought tolerance at the vegetative stages of growth and promoted both effective photosynthesis and a reduction in the water loss rate under drought conditions. Importantly, the OsTF1L overexpressing plants showed a higher drought tolerance at the reproductive stage of growth with a higher grain yield than non-transgenic controls under field-drought conditions. Genome-wide analysis of OsTF1L overexpression plants revealed up-regulation of drought-inducible, stomatal movement and lignin biosynthetic genes. Overexpression of OsTF1L promoted accumulation of lignin in shoots, whereas the RNAi lines showed opposite patterns of lignin accumulation. OsTF1L is mainly expressed in outer cell layers including the epidermis, and the vasculature of the shoots, which coincides with areas of lignification. In addition, OsTF1L overexpression enhances stomatal closure under drought conditions resulted in drought tolerance. More importantly, OsTF1L directly bound to the promoters of lignin biosynthesis and drought-related genes involving poxN/PRX38, Nodulin protein, DHHC4, CASPL5B1 and AAA-type ATPase. Collectively, our results provide a new insight into the role of OsTF1L in enhancing drought tolerance through lignin biosynthesis and stomatal closure in rice. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
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Genomics-based precision breeding approaches to improve drought tolerance in rice.
Swamy, B P Mallikarjuna; Kumar, Arvind
2013-12-01
Rice (Oryza sativa L.), the major staple food crop of the world, faces a severe threat from widespread drought. The development of drought-tolerant rice varieties is considered a feasible option to counteract drought stress. The screening of rice germplasm under drought and its characterization at the morphological, genetic, and molecular levels revealed the existence of genetic variation for drought tolerance within the rice gene pool. The improvements made in managed drought screening and selection for grain yield under drought have significantly contributed to progress in drought breeding programs. The availability of rice genome sequence information, genome-wide molecular markers, and low-cost genotyping platforms now makes it possible to routinely apply marker-assisted breeding approaches to improve grain yield under drought. Grain yield QTLs with a large and consistent effect under drought have been indentified and successfully pyramided in popular rice mega-varieties. Various rice functional genomics resources, databases, tools, and recent advances in "-omics" are facilitating the characterization of genes and pathways involved in drought tolerance, providing the basis for candidate gene identification and allele mining. The transgenic approach is successful in generating drought tolerance in rice under controlled conditions, but field-level testing is necessary. Genomics-assisted drought breeding approaches hold great promise, but a well-planned integration with standardized phenotyping is highly essential to exploit their full potential. Copyright © 2013 Elsevier Inc. All rights reserved.
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Redman, Regina S.; Kim, Yong Ok; Woodward, Claire J. D. A.; Greer, Chris; Espino, Luis; Doty, Sharon L.; Rodriguez, Rusty J.
2011-01-01
Climate change and catastrophic events have contributed to rice shortages in several regions due to decreased water availability and soil salinization. Although not adapted to salt or drought stress, two commercial rice varieties achieved tolerance to these stresses by colonizing them with Class 2 fungal endophytes isolated from plants growing across moisture and salinity gradients. Plant growth and development, water usage, ROS sensitivity and osmolytes were measured with and without stress under controlled conditions. The endophytes conferred salt, drought and cold tolerance to growth chamber and greenhouse grown plants. Endophytes reduced water consumption by 20–30% and increased growth rate, reproductive yield, and biomass of greenhouse grown plants. In the absence of stress, there was no apparent cost of the endophytes to plants, however, endophyte colonization decreased from 100% at planting to 65% compared to greenhouse plants grown under continual stress (maintained 100% colonization). These findings indicate that rice plants can exhibit enhanced stress tolerance via symbiosis with Class 2 endophytes, and suggest that symbiotic technology may be useful in mitigating impacts of climate change on other crops and expanding agricultural production onto marginal lands. PMID:21750695
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Redman, R.S.; Kim, Y.-O.; Woodward, C.J.D.A.; Greer, C.; Espino, L.; Doty, S.L.; Rodriguez, R.J.
2011-01-01
Climate change and catastrophic events have contributed to rice shortages in several regions due to decreased water availability and soil salinization. Although not adapted to salt or drought stress, two commercial rice varieties achieved tolerance to these stresses by colonizing them with Class 2 fungal endophytes isolated from plants growing across moisture and salinity gradients. Plant growth and development, water usage, ROS sensitivity and osmolytes were measured with and without stress under controlled conditions. The endophytes conferred salt, drought and cold tolerance to growth chamber and greenhouse grown plants. Endophytes reduced water consumption by 20–30% and increased growth rate, reproductive yield, and biomass of greenhouse grown plants. In the absence of stress, there was no apparent cost of the endophytes to plants, however, endophyte colonization decreased from 100% at planting to 65% compared to greenhouse plants grown under continual stress (maintained 100% colonization). These findings indicate that rice plants can exhibit enhanced stress tolerance via symbiosis with Class 2 endophytes, and suggest that symbiotic technology may be useful in mitigating impacts of climate change on other crops and expanding agricultural production onto marginal lands.
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Identification and comparative analysis of drought-associated microRNAs in two cowpea genotypes.
Barrera-Figueroa, Blanca E; Gao, Lei; Diop, Ndeye N; Wu, Zhigang; Ehlers, Jeffrey D; Roberts, Philip A; Close, Timothy J; Zhu, Jian-Kang; Liu, Renyi
2011-09-17
Cowpea (Vigna unguiculata) is an important crop in arid and semi-arid regions and is a good model for studying drought tolerance. MicroRNAs (miRNAs) are known to play critical roles in plant stress responses, but drought-associated miRNAs have not been identified in cowpea. In addition, it is not understood how miRNAs might contribute to different capacities of drought tolerance in different cowpea genotypes. We generated deep sequencing small RNA reads from two cowpea genotypes (CB46, drought-sensitive, and IT93K503-1, drought-tolerant) that grew under well-watered and drought stress conditions. We mapped small RNA reads to cowpea genomic sequences and identified 157 miRNA genes that belong to 89 families. Among 44 drought-associated miRNAs, 30 were upregulated in drought condition and 14 were downregulated. Although miRNA expression was in general consistent in two genotypes, we found that nine miRNAs were predominantly or exclusively expressed in one of the two genotypes and that 11 miRNAs were drought-regulated in only one genotype, but not the other. These results suggest that miRNAs may play important roles in drought tolerance in cowpea and may be a key factor in determining the level of drought tolerance in different cowpea genotypes.
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Xiaoqing Yu; Guihua Bai; Shuwei Liu; Na Luo; Ying Wang; Douglas S. Richmond; Paula M. Pijut; Scott A. Jackson; Jianming Yu; Yiwei Jiang
2013-01-01
Drought is a major environmental stress limiting growth of perennial grasses in temperate regions. Plant drought tolerance is a complex trait that is controlled by multiple genes. Candidate gene association mapping provides a powerful tool for dissection of complex traits. Candidate gene association mapping of drought tolerance traits was conducted in 192 diverse...
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Fu, Lili; Ding, Zehong; Han, Bingying; Hu, Wei; Li, Yajun; Zhang, Jiaming
2016-02-25
Cassava is an important tropical and sub-tropical root crop that is adapted to drought environment. However, severe drought stress significantly influences biomass accumulation and starchy root production. The mechanism underlying drought-tolerance remains obscure in cassava. In this study, changes of physiological characters and gene transcriptome profiles were investigated under dehydration stress simulated by polyethylene glycol (PEG) treatments. Five traits, including peroxidase (POD) activity, proline content, malondialdehyde (MDA), soluble sugar and soluble protein, were all dramatically induced in response to PEG treatment. RNA-seq analysis revealed a gradient decrease of differentially expressed (DE) gene number in tissues from bottom to top of a plant, suggesting that cassava root has a quicker response and more induced/depressed DE genes than leaves in response to drought. Overall, dynamic changes of gene expression profiles in cassava root and leaves were uncovered: genes related to glycolysis, abscisic acid and ethylene biosynthesis, lipid metabolism, protein degradation, and second metabolism of flavonoids were significantly induced, while genes associated with cell cycle/organization, cell wall synthesis and degradation, DNA synthesis and chromatin structure, protein synthesis, light reaction of photosynthesis, gibberelin pathways and abiotic stress were greatly depressed. Finally, novel pathways in ABA-dependent and ABA-independent regulatory networks underlying PEG-induced dehydration response in cassava were detected, and the RNA-Seq results of a subset of fifteen genes were confirmed by real-time PCR. The findings will improve our understanding of the mechanism related to dehydration stress-tolerance in cassava and will provide useful candidate genes for breeding of cassava varieties better adapted to drought environment.
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Fu, Lili; Ding, Zehong; Han, Bingying; Hu, Wei; Li, Yajun; Zhang, Jiaming
2016-01-01
Cassava is an important tropical and sub-tropical root crop that is adapted to drought environment. However, severe drought stress significantly influences biomass accumulation and starchy root production. The mechanism underlying drought-tolerance remains obscure in cassava. In this study, changes of physiological characters and gene transcriptome profiles were investigated under dehydration stress simulated by polyethylene glycol (PEG) treatments. Five traits, including peroxidase (POD) activity, proline content, malondialdehyde (MDA), soluble sugar and soluble protein, were all dramatically induced in response to PEG treatment. RNA-seq analysis revealed a gradient decrease of differentially expressed (DE) gene number in tissues from bottom to top of a plant, suggesting that cassava root has a quicker response and more induced/depressed DE genes than leaves in response to drought. Overall, dynamic changes of gene expression profiles in cassava root and leaves were uncovered: genes related to glycolysis, abscisic acid and ethylene biosynthesis, lipid metabolism, protein degradation, and second metabolism of flavonoids were significantly induced, while genes associated with cell cycle/organization, cell wall synthesis and degradation, DNA synthesis and chromatin structure, protein synthesis, light reaction of photosynthesis, gibberelin pathways and abiotic stress were greatly depressed. Finally, novel pathways in ABA-dependent and ABA-independent regulatory networks underlying PEG-induced dehydration response in cassava were detected, and the RNA-Seq results of a subset of fifteen genes were confirmed by real-time PCR. The findings will improve our understanding of the mechanism related to dehydration stress-tolerance in cassava and will provide useful candidate genes for breeding of cassava varieties better adapted to drought environment. PMID:26927071
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Quiroga, Gabriela; Erice, Gorka; Aroca, Ricardo; Chaumont, François; Ruiz-Lozano, Juan M.
2017-01-01
The arbuscular mycorrhizal (AM) symbiosis has been shown to improve maize tolerance to different drought stress scenarios by regulating a wide range of host plants aquaporins. The objective of this study was to highlight the differences in aquaporin regulation by comparing the effects of the AM symbiosis on root aquaporin gene expression and plant physiology in two maize cultivars with contrasting drought sensitivity. This information would help to identify key aquaporin genes involved in the enhanced drought tolerance by the AM symbiosis. Results showed that when plants were subjected to drought stress the AM symbiosis induced a higher improvement of physiological parameters in drought-sensitive plants than in drought-tolerant plants. These include efficiency of photosystem II, membrane stability, accumulation of soluble sugars and plant biomass production. Thus, drought-sensitive plants obtained higher physiological benefit from the AM symbiosis. In addition, the genes ZmPIP1;1, ZmPIP1;3, ZmPIP1;4, ZmPIP1;6, ZmPIP2;2, ZmPIP2;4, ZmTIP1;1, and ZmTIP2;3 were down-regulated by the AM symbiosis in the drought-sensitive cultivar and only ZmTIP4;1 was up-regulated. In contrast, in the drought-tolerant cultivar only three of the studied aquaporin genes (ZmPIP1;6, ZmPIP2;2, and ZmTIP4;1) were regulated by the AM symbiosis, resulting induced. Results in the drought-sensitive cultivar are in line with the hypothesis that down-regulation of aquaporins under water deprivation could be a way to minimize water loss, and the AM symbiosis could be helping the plant in this regulation. Indeed, during drought stress episodes, water conservation is critical for plant survival and productivity, and is achieved by an efficient uptake and stringently regulated water loss, in which aquaporins participate. Moreover, the broader and contrasting regulation of these aquaporins by the AM symbiosis in the drought-sensitive than the drought-tolerant cultivar suggests a role of these aquaporins in water homeostasis or in the transport of other solutes of physiological importance in both cultivars under drought stress conditions, which may be important for the AM-induced tolerance to drought stress. PMID:28674550
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Characterization of some bread wheat genotypes using molecular markers for drought tolerance.
Ateş Sönmezoğlu, Özlem; Terzi, Begüm
2018-02-01
Because of its wide geographical adaptation and importance in human nutrition, wheat is one of the most important crops in the world. However, wheat yield has reduced due to drought stress posing threat to sustainability and world food security in agricultural production. The first stage of drought tolerant variety breeding occurs on the molecular and biochemical characterization and classification of wheat genotypes. The aim of the present study is characterization of widely grown bread wheat cultivars and breeding lines for drought tolerance so as to be adapted to different regions in Turkey. The genotypes were screened with molecular markers for the presence of QTLs mapped to different chromosomes. Results of the molecular studies identified and detected 15 polymorphic SSR markers which gave the clearest PCR bands among the control genotypes. At the end of the research, bread wheat genotypes which were classified for tolerance or sensitivity to drought and the genetic similarity within control varieties were determined by molecular markers. According to SSR based dendrogram, two main groups were obtained for drought tolerance. At end of the molecular screening with SSR primers, genetic similarity coefficients were obtained that ranged from 0.14 to 0.71. The ones numbered 8 and 11 were the closest genotypes to drought tolerant cultivar Gerek 79 and the furthest genotypes from this cultivar were number 16 and to drought sensitive cultivar Sultan 95. The genotypes as drought tolerance due to their SSR markers scores are expected to provide useful information for drought related molecular breeding studies.
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Sharma, Marisha; Gupta, Sunil K; Majumder, Baisakhi; Maurya, Vivek K; Deeba, Farah; Alam, Afroz; Pandey, Vivek
2017-06-23
Salicylic acid (SA) induced drought tolerance can be a key trait for increasing and stabilizing wheat production. These SA induced traits were studied in two Triticum aestivum L. varieties; drought tolerant, Kundan and drought sensitive, Lok1 under two different water deficit regimes: and rehydration at vegetative and flowering stages. SA alleviated the negative effects of water stress on photosynthesis more in Kundan. SA induced defense responses against drought by increasing antioxidative enzymes and osmolytes (proline and total soluble sugars). Differential proteomics revealed major role of carbon metabolism and signal transduction in enhancing drought tolerance in Kundan which was shifted towards defense, energy production and protection in Lok1. Thioredoxins played important role between SA and redox signaling in activating defense responses. SA showed substantial impact on physiology and carbon assimilation in tolerant variety for better growth under drought. Lok1 exhibited SA induced drought tolerance through enhanced defense system and energy metabolism. Plants after rehydration showed complete recovery of physiological functions under SA treatment. SA mediated constitutive defense against water stress did not compromise yield. These results suggest that exogenously applied SA under drought stress confer growth promoting and stress priming effects on wheat plants thus alleviating yield limitation. Studies have shown morphological, physiological and biochemical aspects associated with the SA mediated drought tolerance in wheat while understanding of molecular mechanism is limited. Herein, proteomics approach has identified significantly changed proteins and their potential relevance to SA mediated drought stress responses in drought tolerant and sensitive wheat varieties. SA regulates wide range of processes such as photosynthesis, carbon assimilation, protein metabolism, amino acid and energy metabolism, redox homeostasis and signal transduction under drought. Proteome response to SA during vegetative and reproductive growth gave an insight on mechanism related water stress acclimation for growth and development to attain potential yield under drought. The knowledge gained can be potentially applied to provide fundamental basis for new strategies aiming towards improved crop drought tolerance and productivity. Copyright © 2017 Elsevier B.V. All rights reserved.
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Yang, Liming; Fountain, Jake C.; Wang, Hui; Ni, Xinzhi; Ji, Pingsheng; Lee, Robert D.; Kemerait, Robert C.; Scully, Brian T.; Guo, Baozhu
2015-01-01
Drought stress decreases crop growth, yield, and can further exacerbate pre-harvest aflatoxin contamination. Tolerance and adaptation to drought stress is an important trait of agricultural crops like maize. However, maize genotypes with contrasting drought tolerances have been shown to possess both common and genotype-specific adaptations to cope with drought stress. In this research, the physiological and metabolic response patterns in the leaves of maize seedlings subjected to drought stress were investigated using six maize genotypes including: A638, B73, Grace-E5, Lo964, Lo1016, and Va35. During drought treatments, drought-sensitive maize seedlings displayed more severe symptoms such as chlorosis and wilting, exhibited significant decreases in photosynthetic parameters, and accumulated significantly more reactive oxygen species (ROS) and reactive nitrogen species (RNS) than tolerant genotypes. Sensitive genotypes also showed rapid increases in enzyme activities involved in ROS and RNS metabolism. However, the measured antioxidant enzyme activities were higher in the tolerant genotypes than in the sensitive genotypes in which increased rapidly following drought stress. The results suggest that drought stress causes differential responses to oxidative and nitrosative stress in maize genotypes with tolerant genotypes with slower reaction and less ROS and RNS production than sensitive ones. These differential patterns may be utilized as potential biological markers for use in marker assisted breeding. PMID:26492235
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Transcriptomic Changes of Drought-Tolerant and Sensitive Banana Cultivars Exposed to Drought Stress
Muthusamy, Muthusamy; Uma, Subbaraya; Backiyarani, Suthanthiram; Saraswathi, Marimuthu Somasundaram; Chandrasekar, Arumugam
2016-01-01
In banana, drought responsive gene expression profiles of drought-tolerant and sensitive genotypes remain largely unexplored. In this research, the transcriptome of drought-tolerant banana cultivar (Saba, ABB genome) and sensitive cultivar (Grand Naine, AAA genome) was monitored using mRNA-Seq under control and drought stress condition. A total of 162.36 million reads from tolerant and 126.58 million reads from sensitive libraries were produced and mapped onto the Musa acuminata genome sequence and assembled into 23,096 and 23,079 unigenes. Differential gene expression between two conditions (control and drought) showed that at least 2268 and 2963 statistically significant, functionally known, non-redundant differentially expressed genes (DEGs) from tolerant and sensitive libraries. Drought has up-regulated 991 and 1378 DEGs and down-regulated 1104 and 1585 DEGs respectively in tolerant and sensitive libraries. Among DEGs, 15.9% are coding for transcription factors (TFs) comprising 46 families and 9.5% of DEGs are constituted by protein kinases from 82 families. Most enriched DEGs are mainly involved in protein modifications, lipid metabolism, alkaloid biosynthesis, carbohydrate degradation, glycan metabolism, and biosynthesis of amino acid, cofactor, nucleotide-sugar, hormone, terpenoids and other secondary metabolites. Several, specific genotype-dependent gene expression pattern was observed for drought stress in both cultivars. A subset of 9 DEGs was confirmed using quantitative reverse transcription-PCR. These results will provide necessary information for developing drought-resilient banana plants. PMID:27867388
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Gahlaut, Vijay; Jaiswal, Vandana; Kumar, Anuj; Gupta, Pushpendra Kumar
2016-11-01
TFs involved in drought tolerance in plants may be utilized in future for developing drought tolerant cultivars of wheat and some other crops. Plants have developed a fairly complex stress response system to deal with drought and other abiotic stresses. These response systems often make use of transcription factors (TFs); a gene encoding a specific TF together with -its target genes constitute a regulon, and take part in signal transduction to activate/silence genes involved in response to drought. Since, five specific families of TFs (out of >80 known families of TFs) have gained widespread attention on account of their significant role in drought tolerance in plants, TFs and regulons belonging to these five multi-gene families (AP2/EREBP, bZIP, MYB/MYC, NAC and WRKY) have been described and their role in improving drought tolerance discussed in this brief review. These TFs often undergo reversible phosphorylation to perform their function, and are also involved in complex networks. Therefore, some details about reversible phosphorylation of TFs by different protein kinases/phosphatases and the co-regulatory networks, which involve either only TFs or TFs with miRNAs, have also been discussed. Literature on transgenics involving genes encoding TFs and that on QTLs and markers associated with TF genes involved in drought tolerance has also been reviewed. Throughout the review, there is a major emphasis on wheat as an important crop, although examples from the model cereal rice (sometimes maize also), and the model plant Arabidopsis have also been used. This knowledge base may eventually allow the use of TF genes for development of drought tolerant cultivars, particularly in wheat.
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Liang, Junjun; Chen, Xin; Deng, Guangbing; Pan, Zhifen; Zhang, Haili; Li, Qiao; Yang, Kaijun; Long, Hai; Yu, Maoqun
2017-10-11
The harsh environment on the Qinghai-Tibetan Plateau gives Tibetan hulless barley (Hordeum vulgare var. nudum) great ability to resist adversities such as drought, salinity, and low temperature, and makes it a good subject for the analysis of drought tolerance mechanism. To elucidate the specific gene networks and pathways that contribute to its drought tolerance, and for identifying new candidate genes for breeding purposes, we performed a transcriptomic analysis using two accessions of Tibetan hulless barley, namely Z772 (drought-tolerant) and Z013 (drought-sensitive). There were more up-regulated genes of Z772 than Z013 under both mild (5439-VS-2604) and severe (7203-VS-3359) dehydration treatments. Under mild dehydration stress, the pathways exclusively enriched in drought-tolerance genotype Z772 included Protein processing in endoplasmic reticulum, tricarboxylic acid (TCA) cycle, Wax biosynthesis, and Spliceosome. Under severe dehydration stress, the pathways that were mainly enriched in Z772 included Carbon fixation in photosynthetic organisms, Pyruvate metabolism, Porphyrin and chlorophyll metabolism. The main differentially expressed genes (DEGs) in response to dehydration stress and genes whose expression was different between tolerant and sensitive genotypes were presented in this study, respectively. The candidate genes for drought tolerance were selected based on their expression patterns. The RNA-Seq data obtained in this study provided an initial overview on global gene expression patterns and networks that related to dehydration shock in Tibetan hulless barley. Furthermore, these data provided pathways and a targeted set of candidate genes that might be essential for deep analyzing the molecular mechanisms of plant tolerance to drought stress.
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A transposable element in a NAC gene is associated with drought tolerance in maize seedlings
Mao, Hude; Wang, Hongwei; Liu, Shengxue; Li, Zhigang; Yang, Xiaohong; Yan, Jianbing; Li, Jiansheng; Tran, Lam-Son Phan; Qin, Feng
2015-01-01
Drought represents a major constraint on maize production worldwide. Understanding the genetic basis for natural variation in drought tolerance of maize may facilitate efforts to improve this trait in cultivated germplasm. Here, using a genome-wide association study, we show that a miniature inverted-repeat transposable element (MITE) inserted in the promoter of a NAC gene (ZmNAC111) is significantly associated with natural variation in maize drought tolerance. The 82-bp MITE represses ZmNAC111 expression via RNA-directed DNA methylation and H3K9 dimethylation when heterologously expressed in Arabidopsis. Increasing ZmNAC111 expression in transgenic maize enhances drought tolerance at the seedling stage, improves water-use efficiency and induces upregulation of drought-responsive genes under water stress. The MITE insertion in the ZmNAC111 promoter appears to have occurred after maize domestication and spread among temperate germplasm. The identification of this MITE insertion provides insight into the genetic basis for natural variation in maize drought tolerance. PMID:26387805
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Liang, Chengzhen; Meng, Zhaohong; Meng, Zhigang; Malik, Waqas; Yan, Rong; Lwin, Khin Myat; Lin, Fazhuang; Wang, Yuan; Sun, Guoqing; Zhou, Tao; Zhu, Tao; Li, Jianying; Jin, Shuangxia; Guo, Sandui; Zhang, Rui
2016-10-07
The bZIP transcription factor (TF) act as an important regulator for the abscisic acid (ABA) mediated abiotic stresses signaling pathways in plants. Here, we reported the cloning and characterization of GhABF2, encoding for typical cotton bZIP TF. Overexpression of GhABF2 significantly improved drought and salt stress tolerance both in Arabidopsis and cotton. However, silencing of GhABF2 made transgenic cotton sensitive to PEG osmotic and salt stress. Expression of GhABF2 was induced by drought and ABA treatments but repressed by high salinity. Transcriptome analysis indicated that GhABF2 increases drought and salt tolerance by regulating genes related to ABA, drought and salt response. The proline contents, activity of superoxide dismutase (SOD) and catalase (CAT) were also significantly increased in GhABF2-overexpression cottons in comparison to wild type after drought and salt treatment. Further, an increase in fiber yield under drought and saline-alkali wetland exhibited the important role of GhABF2 in enhancing the drought and salt tolerance in transgenic lines. In conclusion, manipulation of GhABF2 by biotechnological tools could be a sustainable strategy to deploy drought and salt tolerance in cotton.
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Skovlund, Gitte; Damgaard, Christian; Bayley, Mark; Holmstrup, Martin
2006-12-01
The ability of Collembola to survive drought stress is crucial for their distribution in the terrestrial environment. Previous studies have suggested that several toxic compounds affect the drought tolerance of Folsomia candida in a synergistic manner and that these compounds have the feature in common that they elicit their toxicity by causing membrane damage. We hypothesised that the detrimental effect of toxic chemicals on drought tolerance in F. candida depends on the lipophilicity (log K(ow)) of the compound because a higher log K(ow) would mean a closer interaction with membranes. In this study the three chemicals 4-nonylphenol, pyrene and p,p'-DDE were tested. Surprisingly, 4-nonylphenol, with the lowest log K(ow), was the most potent with respect to reducing drought tolerance followed by pyrene, suggesting that interactions between drought tolerance and chemical stress do not depend on lipophilicity alone.
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Augustine, Sruthy Maria; Ashwin Narayan, J; Syamaladevi, Divya P; Appunu, C; Chakravarthi, M; Ravichandran, V; Tuteja, Narendra; Subramonian, N
2015-02-01
EaDREB2 overexpressed in sugarcane enhanced tolerance to drought and salinity. When co-transformed with plant DNA helicase gene, DREB2 showed greater level of salinity tolerance than in single-gene transgenics. Drought is one of the most challenging agricultural issues limiting sustainable sugarcane production and can potentially cause up to 50 % yield loss. DREB proteins play a vital regulatory role in abiotic stress tolerance in plants. We previously reported that expression of EaDREB2 is enhanced by drought stress in Erianthus arundinaceus. In this study, we have isolated the DREB2 gene from E. arundinaceus, transformed one of the most popular sugarcane variety Co 86032 in tropical India with EaDREB2 through Agrobacterium-mediated transformation, pyramided the EaDREB2 gene with the gene coding for PDH45 driven by Port Ubi 2.3 promoter through particle bombardment and evaluated the V1 transgenics for soil deficit moisture and salinity stresses. Soil moisture stress was imposed at the tillering phase by withholding irrigation. Physiological, molecular and morphological parameters were used to assess drought tolerance. Salinity tolerance was assessed through leaf disc senescence and bud sprout assays under salinity stress. Our results indicate that overexpression of EaDREB2 in sugarcane enhances drought and salinity tolerance to a greater extent than the untransformed control plants. This is the first report of the co-transformation of EaDREB2 and PDH45 which shows higher salinity tolerance but lower drought tolerance than EaDREB2 alone. The present study seems to suggest that, for combining drought and salinity tolerance together, co-transformation is a better approach.
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Wei, Xiaojing; Savage, Jessica A; Riggs, Charlotte E; Cavender-Bares, Jeannine
2017-05-01
Environmental filtering is an important community assembly process influencing species distributions. Contrasting species abundance patterns along environmental gradients are commonly used to provide evidence for environmental filtering. However, the same abundance patterns may result from alternative or concurrent assembly processes. Experimental tests are an important means to decipher whether species fitness varies with environment, in the absence of dispersal constraints and biotic interactions, and to draw conclusions about the importance of environmental filtering in community assembly. We performed an experimental test of environmental filtering in 14 closely related willow and poplar species (family Salicaceae) by transplanting cuttings of each species into 40 common gardens established along a natural hydrologic gradient in the field, where competition was minimized and herbivory was controlled. We analyzed species fitness responses to the hydrologic environment based on cumulative growth and survival over two years using aster fitness models. We also examined variation in nine drought and flooding tolerance traits expected to contribute to performance based on a priori understanding of plant function in relation to water availability and stress. We found substantial evidence that environmental filtering along the hydrologic gradient played a critical role in determining species distributions. Fitness variation of each species in the field experiment was used to model their water table depth optima. These optima predicted 68% of the variation in species realized hydrologic niches based on peak abundance in naturally assembled communities in the surrounding region. Multiple traits associated with water transport efficiency and water stress tolerance were correlated with species hydrologic niches, but they did not necessarily covary with each other. As a consequence, species occupying similar hydrologic niches had different combinations of trait values. Moreover, individual traits were less phylogenetically conserved than species hydrologic niches and integrated water stress tolerance as determined by multiple traits. We conclude that differential fitness among species along the hydrologic gradient was the consequence of multiple traits associated with water transport and water stress tolerance, expressed in different combinations by different species. Varying environmental tolerance, in turn, played a critical role in driving niche segregation among close relatives along the hydrologic gradient. © 2017 by the Ecological Society of America.
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The correlations and sequence of plant stomatal, hydraulic, and wilting responses to drought
Bartlett, Megan K.; Klein, Tamir; Jansen, Steven; Choat, Brendan; Sack, Lawren
2016-01-01
Climate change is expected to exacerbate drought for many plants, making drought tolerance a key driver of species and ecosystem responses. Plant drought tolerance is determined by multiple traits, but the relationships among traits, either within individual plants or across species, have not been evaluated for general patterns across plant diversity. We synthesized the published data for stomatal closure, wilting, declines in hydraulic conductivity in the leaves, stems, and roots, and plant mortality for 262 woody angiosperm and 48 gymnosperm species. We evaluated the correlations among the drought tolerance traits across species, and the general sequence of water potential thresholds for these traits within individual plants. The trait correlations across species provide a framework for predicting plant responses to a wide range of water stress from one or two sampled traits, increasing the ability to rapidly characterize drought tolerance across diverse species. Analyzing these correlations also identified correlations among the leaf and stem hydraulic traits and the wilting point, or turgor loss point, beyond those expected from shared ancestry or independent associations with water stress alone. Further, on average, the angiosperm species generally exhibited a sequence of drought tolerance traits that is expected to limit severe tissue damage during drought, such as wilting and substantial stem embolism. This synthesis of the relationships among the drought tolerance traits provides crucial, empirically supported insight into representing variation in multiple traits in models of plant and ecosystem responses to drought. PMID:27807136
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The correlations and sequence of plant stomatal, hydraulic, and wilting responses to drought.
Bartlett, Megan K; Klein, Tamir; Jansen, Steven; Choat, Brendan; Sack, Lawren
2016-11-15
Climate change is expected to exacerbate drought for many plants, making drought tolerance a key driver of species and ecosystem responses. Plant drought tolerance is determined by multiple traits, but the relationships among traits, either within individual plants or across species, have not been evaluated for general patterns across plant diversity. We synthesized the published data for stomatal closure, wilting, declines in hydraulic conductivity in the leaves, stems, and roots, and plant mortality for 262 woody angiosperm and 48 gymnosperm species. We evaluated the correlations among the drought tolerance traits across species, and the general sequence of water potential thresholds for these traits within individual plants. The trait correlations across species provide a framework for predicting plant responses to a wide range of water stress from one or two sampled traits, increasing the ability to rapidly characterize drought tolerance across diverse species. Analyzing these correlations also identified correlations among the leaf and stem hydraulic traits and the wilting point, or turgor loss point, beyond those expected from shared ancestry or independent associations with water stress alone. Further, on average, the angiosperm species generally exhibited a sequence of drought tolerance traits that is expected to limit severe tissue damage during drought, such as wilting and substantial stem embolism. This synthesis of the relationships among the drought tolerance traits provides crucial, empirically supported insight into representing variation in multiple traits in models of plant and ecosystem responses to drought.
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Guo, B Z; Xu, G; Cao, Y G; Holbrook, C C; Lynch, R E
2006-02-01
Preharvest aflatoxin contamination has been identified by the peanut industry as a serious issue in food safety and human health because of the carcinogenic toxicity. Drought stress is the most important environmental factor exacerbating Aspergillus infection and aflatoxin contamination in peanut. The development of drought-tolerant peanut cultivars could reduce aflatoxin contamination and would represent a major advance in the peanut industry. In this study, we identified a novel PLD gene in peanut (Arachis hypogaea), encoding a putative phospholipase D (PLD, EC 3.1.4.4). The completed cDNA sequence was obtained by using the consensus-degenerated hybrid oligonucleotide primer strategy. The deduced amino acid sequence shows high identity with known PLDs, and has similar conserved domains. The PLD gene expression under drought stress has been studied using four peanut lines: Tifton 8 and A13 (both drought tolerant) and Georgia Green (moderate) and PI 196754 (drought sensitive). Northern analysis showed that PLD gene expression was induced faster by drought stress in the drought-sensitive lines than the drought tolerance lines. Southern analysis showed that cultivated peanut has multiple copies (3 to 5 copies) of the PLD gene. These results suggest that peanut PLD may be involved in drought sensitivity and tolerance responses. Peanut PLD gene expression may be useful as a tool in germplasm screening for drought tolerance.
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Badhan, Sapna; Kole, Pravas; Ball, Andrew; Mantri, Nitin
2018-06-13
Chickpea (Cicer arietinum L.) is the second most important winter crop which is consumed globally due to its high nutritional value. Chickpea as one of the leguminous crop is important in crop rotation with cereal crops like wheat and barley. The main constraints for chickpea production are abiotic stresses such as drought, salinity, and heat. Among these, drought is a major cause of the decline in chickpea production in worldwide. Studies conducted so far have provided a limited insight into different genetic pathways associated with drought tolerance/response. In this study, the leaf tissue from shoots apical meristem stage of drought tolerant (ICC8261) and drought sensitive (ICC283) genotypes were analysed using RNA sequencing to identify genes/pathways associated with drought tolerance/sensitivity in both genotypes. It was observed that genes related to ethylene response, MYB-related protein, xyloglucan endotransglycosylase, alkane hydroxylase MAH-like, BON-1 associated, peroxidase 3, cysteine-rich and transmembrane domain, vignain and mitochondrial uncoupling were specifically up-regulated in the tolerant genotype whereas, same genes were down-regulated in sensitive genotype. The crosstalk between the different hormones and transcriptional factors involved in drought tolerance and sensitivity in both genotypes make them great candidates for future research. Copyright © 2018 Elsevier Masson SAS. All rights reserved.
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Medeiros, Juliana S.; Ward, Joy K.
2013-01-01
Summary Changes in atmospheric carbon dioxide concentration ([CO2]) affect plant carbon/water trade-offs, with implications for drought tolerance. Leaf-level studies often indicate that drought tolerance may increase with rising [CO2], but integrated leaf and xylem responses are not well understood in this respect. In addition, the influence of low [CO2] of the last glacial period on drought tolerance and xylem properties is not well understood.We investigated the interactive effects of a broad range of [CO2] and plant water potentials on leaf function, xylem structure and function and the integration of leaf and xylem function in Phaseolus vulgaris.Elevated [CO2] decreased vessel implosion strength, reduced conduit specific hydraulic conductance, and compromised leaf specific xylem hydraulic conductance under moderate drought. By contrast, at glacial [CO2], transpiration was maintained under moderate drought via greater conduit specific and leaf specific hydraulic conductance in association with increased vessel implosion strength.Our study involving the integration of leaf and xylem responses suggests that increasing [CO2] does not improve drought tolerance. We show that under glacial conditions changes in leaf and xylem properties could increase drought tolerance, while under future conditions greater productivity may only occur when higher water use can be accommodated. PMID:23668237
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Santos, Tiago Benedito Dos; de Lima, Rogério Barbosa; Nagashima, Getúlio Takashi; Petkowicz, Carmen Lucia de Oliveira; Carpentieri-Pípolo, Valéria; Pereira, Luiz Filipe Protasio; Domingues, Douglas Silva; Vieira, Luiz Gonzaga Esteves
2015-01-01
Increased synthesis of galactinol and raffinose family oligosaccharides (RFOs) has been reported in vegetative tissues in response to a range of abiotic stresses. In this work, we evaluated the transcriptional profile of a Coffea canephora galactinol synthase gene (CcGolS1) in two clones that differed in tolerance to water deficit in order to assess the contribution of this gene to drought tolerance. The expression of CcGolS1 in leaves was differentially regulated by water deficit, depending on the intensity of stress and the genotype. In clone 109A (drought-susceptible), the abundance of CcGolS1 transcripts decreased upon exposure to drought, reaching minimum values during recovery from severe water deficit and stress. In contrast, CcGolS1 gene expression in clone 14 (drought-tolerant) was stimulated by water deficit. Changes in galactinol and RFO content did not correlate with variation in the steady-state transcript level. However, the magnitude of increase in RFO accumulation was higher in the tolerant cultivar, mainly under severe water deficit. The finding that the drought-tolerant coffee clone showed enhanced accumulation of CcGolS1 transcripts and RFOs under water deficit suggests the possibility of using this gene to improve drought tolerance in this important crop. PMID:26273221
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Santos, Tiago Benedito Dos; de Lima, Rogério Barbosa; Nagashima, Getúlio Takashi; Petkowicz, Carmen Lucia de Oliveira; Carpentieri-Pípolo, Valéria; Pereira, Luiz Filipe Protasio; Domingues, Douglas Silva; Vieira, Luiz Gonzaga Esteves
2015-05-01
Increased synthesis of galactinol and raffinose family oligosaccharides (RFOs) has been reported in vegetative tissues in response to a range of abiotic stresses. In this work, we evaluated the transcriptional profile of a Coffea canephora galactinol synthase gene (CcGolS1) in two clones that differed in tolerance to water deficit in order to assess the contribution of this gene to drought tolerance. The expression of CcGolS1 in leaves was differentially regulated by water deficit, depending on the intensity of stress and the genotype. In clone 109A (drought-susceptible), the abundance of CcGolS1 transcripts decreased upon exposure to drought, reaching minimum values during recovery from severe water deficit and stress. In contrast, CcGolS1 gene expression in clone 14 (drought-tolerant) was stimulated by water deficit. Changes in galactinol and RFO content did not correlate with variation in the steady-state transcript level. However, the magnitude of increase in RFO accumulation was higher in the tolerant cultivar, mainly under severe water deficit. The finding that the drought-tolerant coffee clone showed enhanced accumulation of CcGolS1 transcripts and RFOs under water deficit suggests the possibility of using this gene to improve drought tolerance in this important crop.
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Ramírez-Valiente, Jose A; Cavender-Bares, Jeannine
2017-07-01
In seasonally dry tropical forest regions, drought avoidance during the dry season coupled with high assimilation rates in the wet season is hypothesized to be an advantageous strategy for forest trees in regions with severe and long dry seasons. In contrast, where dry seasons are milder, drought tolerance coupled with a conservative resource-use strategy is expected to maximize carbon assimilation throughout the year. Tests of this hypothesis, particularly at the intraspecific level, have been seldom conducted. In this study, we tested the extent to which drought resistance mechanisms and rates of carbon assimilation have evolved under climates with varying dry season length and severity within Quercus oleoidesCham. and Schlect., a tropical dry forest species that is widely distributed in Central America. For this purpose, we conducted a greenhouse experiment where seedlings originating from five populations that vary in rainfall patterns were grown under different watering treatments. Our results revealed that populations from xeric climates with more severe dry seasons exhibited large mesophyllous leaves (with high specific leaf area, SLA), and leaf abscission in response to drought, consistent with a drought-avoidance strategy. In contrast, populations from more mesic climates with less severe dry seasons had small and thick sclerophyllous leaves with low SLA and reduced water potential at the turgor loss point (πtlp), consistent with a drought-tolerance strategy. Mesic populations also showed high plasticity in πtlp in response to water availability, indicating that osmotic adjustment to drought is an important component of this strategy. However, populations with mesophyllous leaves did not have higher maximum carbon assimilation rates under well-watered conditions. Furthermore, SLA was negatively associated with mass-based photosynthetic rates, contrary to expectations of the leaf economics spectrum, indicating that drought-resistance strategies are not necessarily tightly coupled with resource-use strategies. Overall, our study demonstrates the importance of considering intraspecific variation in analyses of the vulnerability of tropical trees to climate change. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
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Quan, Wenli; Hu, Yuanlei; Mu, Zixin; Shi, Haitao; Chan, Zhulong
2018-05-31
PYR/PYLs function as ABA receptors and are key regulators during plant drought stress response. Previously we screened drought tolerance of Arabidopsis ABA receptors PYR/PYLs under the control of five different promoters. In this study, we characterized drought stress tolerance of AtPYL5 transgene under the control of one guard cell specific promoter, pGC1. pGC1::AtPYL5 transgenic Arabidopsis exhibited reduced transpiration rate and decreased water loss after drought treatment. Transformation of pGC1::AtPYL5 in Arabidopsis also decreased oxidative stress damage and improved photosynthesis under drought stress condition. These results indicated that pGC1::AtPYL5 construct is effective and might pave new way to develop genetically engineered plants to improve drought stress tolerance. Copyright © 2018 Elsevier Masson SAS. All rights reserved.
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Woldesemayat, Adugna Abdi; Van Heusden, Peter; Ndimba, Bongani K; Christoffels, Alan
2017-12-22
Drought is the most disastrous abiotic stress that severely affects agricultural productivity worldwide. Understanding the biological basis of drought-regulated traits, requires identification and an in-depth characterization of genetic determinants using model organisms and high-throughput technologies. However, studies on drought tolerance have generally been limited to traditional candidate gene approach that targets only a single gene in a pathway that is related to a trait. In this study, we used sorghum, one of the model crops that is well adapted to arid regions, to mine genes and define determinants for drought tolerance using drought expression libraries and RNA-seq data. We provide an integrated and comparative in silico candidate gene identification, characterization and annotation approach, with an emphasis on genes playing a prominent role in conferring drought tolerance in sorghum. A total of 470 non-redundant functionally annotated drought responsive genes (DRGs) were identified using experimental data from drought responses by employing pairwise sequence similarity searches, pathway and interpro-domain analysis, expression profiling and orthology relation. Comparison of the genomic locations between these genes and sorghum quantitative trait loci (QTLs) showed that 40% of these genes were co-localized with QTLs known for drought tolerance. The genome reannotation conducted using the Program to Assemble Spliced Alignment (PASA), resulted in 9.6% of existing single gene models being updated. In addition, 210 putative novel genes were identified using AUGUSTUS and PASA based analysis on expression dataset. Among these, 50% were single exonic, 69.5% represented drought responsive and 5.7% were complete gene structure models. Analysis of biochemical metabolism revealed 14 metabolic pathways that are related to drought tolerance and also had a strong biological network, among categories of genes involved. Identification of these pathways, signifies the interplay of biochemical reactions that make up the metabolic network, constituting fundamental interface for sorghum defence mechanism against drought stress. This study suggests untapped natural variability in sorghum that could be used for developing drought tolerance. The data presented here, may be regarded as an initial reference point in functional and comparative genomics in the Gramineae family.
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Montwé, David; Isaac-Renton, Miriam; Hamann, Andreas; Spiecker, Heinrich
2016-02-01
Choosing drought-tolerant planting stock in reforestation programs may help adapt forests to climate change. To inform such reforestation strategies, we test lodgepole pine (Pinus contorta Doug. ex Loud. var latifolia Englm.) population response to drought and infer potential benefits of a northward transfer of seeds from drier, southern environments. The objective is addressed by combining dendroecological growth analysis with long-term genetic field trials. Over 500 trees originating from 23 populations across western North America were destructively sampled in three experimental sites in southern British Columbia, representing a climate warming scenario. Growth after 32 years from provenances transferred southward or northward over long distances was significantly lower than growth of local populations. All populations were affected by a severe natural drought event in 2002. The provenances from the most southern locations showed the highest drought tolerance but low productivity. Local provenances were productive and drought tolerant. Provenances from the boreal north showed lower productivity and less drought tolerance on southern test sites than all other sources, implying that maladaptation to drought may prevent boreal populations from taking full advantage of more favorable growing conditions under projected climate change. © 2015 John Wiley & Sons Ltd.
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Yu, Linhui; Chen, Xi; Wang, Zhen; Wang, Shimei; Wang, Yuping; Zhu, Qisheng; Li, Shigui; Xiang, Chengbin
2013-01-01
Enhancing drought tolerance without yield decrease has been a great challenge in crop improvement. Here, we report the Arabidopsis (Arabidopsis thaliana) homodomain-leucine zipper transcription factor Enhanced Drought Tolerance/HOMEODOMAIN GLABROUS11 (EDT1/HDG11) was able to confer drought tolerance and increase grain yield in transgenic rice (Oryza sativa) plants. The improved drought tolerance was associated with a more extensive root system, reduced stomatal density, and higher water use efficiency. The transgenic rice plants also had higher levels of abscisic acid, proline, soluble sugar, and reactive oxygen species-scavenging enzyme activities during stress treatments. The increased grain yield of the transgenic rice was contributed by improved seed setting, larger panicle, and more tillers as well as increased photosynthetic capacity. Digital gene expression analysis indicated that AtEDT1/HDG11 had a significant influence on gene expression profile in rice, which was consistent with the observed phenotypes of transgenic rice plants. Our study shows that AtEDT1/HDG11 can improve both stress tolerance and grain yield in rice, demonstrating the efficacy of AtEDT1/HDG11 in crop improvement. PMID:23735506
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Joshi, Rohit; Wani, Shabir H.; Singh, Balwant; Bohra, Abhishek; Dar, Zahoor A.; Lone, Ajaz A.; Pareek, Ashwani; Singla-Pareek, Sneh L.
2016-01-01
Increasing vulnerability of plants to a variety of stresses such as drought, salt and extreme temperatures poses a global threat to sustained growth and productivity of major crops. Of these stresses, drought represents a considerable threat to plant growth and development. In view of this, developing staple food cultivars with improved drought tolerance emerges as the most sustainable solution toward improving crop productivity in a scenario of climate change. In parallel, unraveling the genetic architecture and the targeted identification of molecular networks using modern “OMICS” analyses, that can underpin drought tolerance mechanisms, is urgently required. Importantly, integrated studies intending to elucidate complex mechanisms can bridge the gap existing in our current knowledge about drought stress tolerance in plants. It is now well established that drought tolerance is regulated by several genes, including transcription factors (TFs) that enable plants to withstand unfavorable conditions, and these remain potential genomic candidates for their wide application in crop breeding. These TFs represent the key molecular switches orchestrating the regulation of plant developmental processes in response to a variety of stresses. The current review aims to offer a deeper understanding of TFs engaged in regulating plant’s response under drought stress and to devise potential strategies to improve plant tolerance against drought. PMID:27471513
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Yang, Zemao; Dai, Zhigang; Lu, Ruike; Wu, Bibo; Tang, Qing; Xu, Ying; Cheng, Chaohua; Su, Jianguang
2017-11-29
Drought stress results in significant crop yield losses. Comparative transcriptome analysis between tolerant and sensitive species can provide insights into drought tolerance mechanisms in jute. We present a comprehensive study on drought tolerance in two jute species-a drought tolerant species (Corchorus olitorius L., GF) and a drought sensitive species (Corchorus capsularis L., YY). In total, 45,831 non-redundant unigenes with average sequence length of 1421 bp were identified. Higher numbers of differentially expressed genes (DEGs) were discovered in YY (794) than in GF (39), implying that YY was relatively more vulnerable or hyper-responsive to drought stress at the molecular level; the two main pathways, phenylpropanoid biosynthesis and peroxisome pathway, significantly involved in scavenging of reactive oxygen species (ROS) and 14 unigenes in the two pathways presented a significant differential expression in response to increase of superoxide. Our classification analysis showed that 1769 transcription factors can be grouped into 81 families and 948 protein kinases (PKs) into 122 families. In YY, we identified 34 TF DEGs from and 23 PK DEGs, including 19 receptor-like kinases (RLKs). Most of these RLKs were downregulated during drought stress, implying their role as negative regulators of the drought tolerance mechanism in jute.
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Dixit, Shalabh; Huang, B Emma; Sta Cruz, Ma Teresa; Maturan, Paul T; Ontoy, Jhon Christian E; Kumar, Arvind
2014-01-01
The coupling of biotic and abiotic stresses leads to high yield losses in rainfed rice (Oryza sativa L.) growing areas. While several studies target these stresses independently, breeding strategies to combat multiple stresses seldom exist. This study reports an integrated strategy that combines QTL mapping and phenotypic selection to develop rice lines with high grain yield (GY) under drought stress and non-stress conditions, and tolerance of rice blast. A blast-tolerant BC2F3-derived population was developed from the cross of tropical japonica cultivar Moroberekan (blast- and drought-tolerant) and high-yielding indica variety Swarna (blast- and drought-susceptible) through phenotypic selection for blast tolerance at the BC2F2 generation. The population was studied for segregation distortion patterns and QTLs for GY under drought were identified along with study of epistatic interactions for the trait. Segregation distortion, in favour of Moroberekan, was observed at 50 of the 59 loci. Majority of these marker loci co-localized with known QTLs for blast tolerance or NBS-LRR disease resistance genes. Despite the presence of segregation distortion, high variation for DTF, PH and GY was observed and several QTLs were identified under drought stress and non-stress conditions for the three traits. Epistatic interactions were also detected for GY which explained a large proportion of phenotypic variance observed in the population. This strategy allowed us to identify QTLs for GY along with rapid development of high-yielding purelines tolerant to blast and drought with considerably reduced efforts. Apart from this, it also allowed us to study the effects of the selection cycle for blast tolerance. The developed lines were screened at IRRI and in the target environment, and drought and blast tolerant lines with high yield were identified. With tolerance to two major stresses and high yield potential, these lines may provide yield stability in rainfed rice areas.
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Yang, Yufeng; Wang, Yannan; Jia, Licong; Yang, Guohong; Xu, Xinzhi; Zhai, Hong; He, Shaozhen; Li, Junxia; Dai, Xiaodong; Qin, Na; Zhu, Cancan; Liu, Qingchang
2018-01-01
Previously, we obtained the sweetpotato somatic hybrid KT1 from a cross between sweetpotato (Ipomoea batatas (L.) Lam.) cv. Kokei No. 14 and its drought-tolerant wild relative I. triloba L. KT1 not only inherited the thick storage root characteristic of Kokei No. 14 but also the drought-tolerance trait of I. triloba L. The aim of this study was to explore the molecular mechanism of the drought tolerance of KT1. Four-week-old in vitro-grown plants of KT1, Kokei No. 14, and I. triloba L. were subjected to a simulated drought stress treatment (30% PEG6000) for 0, 6, 12 and 24 h. Total RNA was extracted from samples at each time point, and then used for transcriptome sequencing. The gene transcript profiles of KT1 and its parents were compared to identify differentially expressed genes, and drought-related modules were screened by a weighted gene co-expression network analysis. The functions of ABI-like protein and Ca2+-ATPase, two proteins screened from the cyan and light yellow modules, were analyzed in terms of their potential roles in drought tolerance in KT1 and its parents. These analyses of the drought responses of KT1 and its somatic donors at the transcriptional level provide new annotations for the molecular mechanism of drought tolerance in the somatic hybrid KT1 and its parents.
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USDA-ARS?s Scientific Manuscript database
Drought is a major environmental factor hampering alfalfa productivity worldwide. Gene banks provide an array of trait diversity, frequently consisting of specific seed collection projects that focused on acquiring germplasm adapted to specific traits such as drought tolerance. These subsets provide...
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NASA Astrophysics Data System (ADS)
Hicks, Lettice; Leizeaga, Ainara; Hawkes, Christine; Rousk, Johannes
2017-04-01
Hydrological regimes will intensify due to climate change, thus increasing the duration and intensity of drought and rainfall events. Rewetting of dry soil is known to stimulate dramatic CO2 releases. A clear understanding of the mechanisms that determine the dynamics of CO2 loss upon rewetting is therefore required to characterise ecosystem C-budgets and predict responses to climate change. Laboratory studies have identified two distinct responses upon rewetting; bacterial growth either increases linearly immediately, with maximal respiration also occurring immediately and decreasing exponentially with time ("Type 1"), or bacterial growth increases exponentially after a period of near-zero growth, with a sustained period of elevated respiration, sometimes followed by a secondary increase in respiration coinciding with the onset of bacterial growth ("Type 2"). A shift from a Type 1 to a Type 2 response has been observed with increasing duration and intensity of drying prior to rewetting. The size of the surviving microbial community after drying, relative to resources available after rewetting, is suggested to dictate whether a Type 1 or 2 response occurs, with more 'harsh' (i.e. longer or more severe) drying reducing microbial biomass such that carbon available upon rewetting is sufficient to support exponential growth (leading to Type 2 response). However, this is yet to be tested in intact ecosystems. We investigated the legacy of drought on microbial responses to drying and rewetting using grassland soils from a natural precipitation gradient in Texas. Mean annual precipitation spanned a 500 mm range (400-900 mm year-1) across the 400 km gradient, while mean annual temperature was constant. Soil properties (pH, SOM) did not vary systematically across the gradient, with differences reflecting land-use history rather than rainfall. Air dried soils from 18 sites were rewetted to 50 % water holding capacity with bacterial growth, fungal growth and respiration measured at high temporal resolution over 7 days. We predicted that there would be a shift in the type of response to rewetting (Type 1 to Type 2) across the gradient, as a consequence of exposure to harsher drying. Further, given the lack of systematic variation in other factors with rainfall, we expected levels of maximal growth and respiration as well as the level of steady state growth and respiration to be similar across the gradient. All soils exhibited a Type 1 response, with respiration, bacterial and fungal growth increasing immediately upon rewetting and typically stabilising after c. 20 hours. There were, however, differences in the magnitude of CO2 release and microbial growth among soils, whereby rewetting of historically wetter soils stimulated higher rates of microbial growth and a greater release of CO2, compared to rewetting of historically drier soils. Contrary to expectations, there was no difference in the type of microbial response to rewetting, but instead a systematic dependence of overall microbial rates, depending on the legacy of drought. This contrasted with previous laboratory studies, suggesting that exposure to drought across the natural gradient was not perceived as 'harsh' by the microbial communities. This may be explained by either (i) differences in resource availability (i.e. plant input) mitigating the microbial susceptibility to drought in intact ecosystems or (ii) microbial tolerance to drought.
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Fan, Qing-Jie; Yan, Feng-Xia; Qiao, Guang; Zhang, Bing-Xue; Wen, Xiao-Peng
2014-01-01
Drought is one of the most severe threats to the growth, development and yield of plant. In order to unravel the molecular basis underlying the high tolerance of pitaya (Hylocereus undatus) to drought stress, suppression subtractive hybridization (SSH) and cDNA microarray approaches were firstly combined to identify the potential important or novel genes involved in the plant responses to drought stress. The forward (drought over drought-free) and reverse (drought-free over drought) suppression subtractive cDNA libraries were constructed using in vitro shoots of cultivar 'Zihonglong' exposed to drought stress and drought-free (control). A total of 2112 clones, among which half were from either forward or reverse SSH library, were randomly picked up to construct a pitaya cDNA microarray. Microarray analysis was carried out to verify the expression fluctuations of this set of clones upon drought treatment compared with the controls. A total of 309 expressed sequence tags (ESTs), 153 from forward library and 156 from reverse library, were obtained, and 138 unique ESTs were identified after sequencing by clustering and blast analyses, which included genes that had been previously reported as responsive to water stress as well as some functionally unknown genes. Thirty six genes were mapped to 47 KEGG pathways, including carbohydrate metabolism, lipid metabolism, energy metabolism, nucleotide metabolism, and amino acid metabolism of pitaya. Expression analysis of the selected ESTs by reverse transcriptase polymerase chain reaction (RT-PCR) corroborated the results of differential screening. Moreover, time-course expression patterns of these selected ESTs further confirmed that they were closely responsive to drought treatment. Among the differentially expressed genes (DEGs), many are related to stress tolerances including drought tolerance. Thereby, the mechanism of drought tolerance of this pitaya genotype is a very complex physiological and biochemical process, in which multiple metabolism pathways and many genes were implicated. The data gained herein provide an insight into the mechanism underlying the drought stress tolerance of pitaya, as well as may facilitate the screening of candidate genes for drought tolerance. © 2013 Elsevier B.V. All rights reserved.
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NASA Astrophysics Data System (ADS)
Vahmani, P.; Ban-Weiss, G.
2016-08-01
During 2012-2014, drought in California resulted in policies to reduce water consumption. One measure pursued was replacing lawns with landscapes that minimize water consumption, such as drought-tolerant vegetation. If implemented at broad scale, this strategy would result in reductions in irrigation and changes in land surface characteristics. In this study, we employ a modified regional climate model to assess the climatic consequences of adopting drought-tolerant vegetation over the Los Angeles metropolitan area. Transforming lawns to drought-tolerant vegetation resulted in daytime warming of up to 1.9°C, largely due to decreases in irrigation that shifted surface energy partitioning toward higher sensible and lower latent heat flux. During nighttime, however, adopting drought-tolerant vegetation caused mean cooling of 3.2°C, due to changes in soil thermodynamic properties and heat exchange dynamics between the surface and subsurface. Our results show that nocturnal cooling effects, which are larger in magnitude and of great importance for public health during heat events, could counterbalance the daytime warming attributed to the studied water conservation strategy. A more aggressive implementation, assuming all urban vegetation was replaced with drought-tolerant vegetation, resulted in an average daytime cooling of 0.2°C, largely due to strengthened sea breeze patterns, highlighting the important role of land surface roughness in this coastal megacity.
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NASA Astrophysics Data System (ADS)
Ban-Weiss, G. A.; Vahmani, P.
2016-12-01
During 2012-2014, drought in California resulted in policies to reduce water consumption. One measure pursued was replacing lawns with landscapes that minimize water consumption, such as drought tolerant vegetation. If implemented at broad scale, this strategy would result in reductions in irrigation, and changes in land surface characteristics. In this study, we employ a modified regional climate model to assess the climatic consequences of adopting drought tolerant vegetation over the Los Angeles metropolitan area. Transforming lawns to drought tolerant vegetation resulted in daytime warming of up to 1.9°C, largely due to decreases in irrigation that shifted surface energy partitioning toward higher sensible and lower latent heat flux. During nighttime, however, adopting drought tolerant vegetation caused mean cooling of about 3°C, due to changes in soil thermodynamic properties and heat exchange dynamics between the surface and ground. Our results show that nocturnal cooling effects, which are larger in magnitude and of great importance for public health during heat events, could counterbalance the daytime warming attributed to the studied water conservation strategy. A more aggressive implementation, assuming all urban vegetation was replaced with drought tolerant vegetation, resulted in an average daytime cooling of 0.2°C, largely due to weakened sea-breeze patterns, highlighting the important role of land surface roughness in this coastal megacity.
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Powell, Thomas L; Wheeler, James K; de Oliveira, Alex A R; da Costa, Antonio Carlos Lola; Saleska, Scott R; Meir, Patrick; Moorcroft, Paul R
2017-10-01
Considerable uncertainty surrounds the impacts of anthropogenic climate change on the composition and structure of Amazon forests. Building upon results from two large-scale ecosystem drought experiments in the eastern Brazilian Amazon that observed increases in mortality rates among some tree species but not others, in this study we investigate the physiological traits underpinning these differential demographic responses. Xylem pressure at 50% conductivity (xylem-P 50 ), leaf turgor loss point (TLP), cellular osmotic potential (π o ), and cellular bulk modulus of elasticity (ε), all traits mechanistically linked to drought tolerance, were measured on upper canopy branches and leaves of mature trees from selected species growing at the two drought experiment sites. Each species was placed a priori into one of four plant functional type (PFT) categories: drought-tolerant versus drought-intolerant based on observed mortality rates, and subdivided into early- versus late-successional based on wood density. We tested the hypotheses that the measured traits would be significantly different between the four PFTs and that they would be spatially conserved across the two experimental sites. Xylem-P 50 , TLP, and π o , but not ε, occurred at significantly higher water potentials for the drought-intolerant PFT compared to the drought-tolerant PFT; however, there were no significant differences between the early- and late-successional PFTs. These results suggest that these three traits are important for determining drought tolerance, and are largely independent of wood density-a trait commonly associated with successional status. Differences in these physiological traits that occurred between the drought-tolerant and drought-intolerant PFTs were conserved between the two research sites, even though they had different soil types and dry-season lengths. This more detailed understanding of how xylem and leaf hydraulic traits vary between co-occuring drought-tolerant and drought-intolerant tropical tree species promises to facilitate a much-needed improvement in the representation of plant hydraulics within terrestrial ecosystem and biosphere models, which will enhance our ability to make robust predictions of how future changes in climate will affect tropical forests. © 2017 John Wiley & Sons Ltd.
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USDA-ARS?s Scientific Manuscript database
Drought is the No. 1 factor that limits agricultural production in the world, thus, making crops more drought tolerant is a major goal in agriculture. Many genes with functions in abiotic stress tolerance were identified, and overexpression of these genes confers increased drought tolerance in trans...
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Sharma, Parbodh C.; Singh, Dhananjay; Sehgal, Deepmala; Singh, Gurbachan; Hash, C.T.; Yadav, Rattan S.
2014-01-01
Earlier, we established that a major drought tolerance QTL on linkage group 2 of pearl millet is also associated with reduced salt uptake and enhanced growth under salt stress. Present study was undertaken to re-assess the performance of drought tolerant (PRLT 2/89-33) and drought sensitive (H 77/833-2) parents along with two QTL-NILs (ICMR 01029 and ICMR 01040), under salinity stress specifically imposed during post-flowering growth stages when plants had developed their ion sinks in full. Time course changes in ionic accumulation and their compartmentalization in different plant parts was studied, specifically to monitor and capture changes conferred by the two alleles at this QTL, at small intervals. Amongst different plant parts, higher accumulation of toxic ion Na+ was recorded in roots. Further, the Na+ concentration in roots of the testcross hybrid of the drought-sensitive parent (H 77/833-2) reached its maximum at ECiw 15 dS m−1 within 24 h after salinity imposition, whereas it continued to increase with time in the testcross hybrids of the drought tolerant parent PRLT 2/89-33 as well as those of its QTL-NILs (ICMR 01029 and ICMR 01004) and reached at its maximum at 120 h stage. Comparison of differential distribution of toxic ions in individual leaves revealed that Na+ ions were not uniformly distributed in the leaves of the drought-tolerant parent and drought-tolerant QTL-NILs; but accumulated preferentially in the older leaves, whereas the hybrid of the drought-sensitive parent showed significantly higher Na+ concentration in all main stem leaves irrespective of their age. Dynamics of chlorophyll and proline concentration variation studied under salt stress at late flowering stages revealed a greater reduction, almost twice, in both leaf chlorophyll and proline concentrations in younger leaves in the hybrids of the sensitive parent as compared to the tolerant parent and QTL NILs. Imposition of salinity stress even at flowering stage affected the yield performance in pearl millet, wherein higher yield was recorded in drought tolerant parent and the two QTL-NILs compared to drought sensitive parent. PMID:24895469
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Furlan, Ana Laura; Bianucci, Eliana; Castro, Stella; Dietz, Karl-Josef
2017-10-01
Legumes belong to the most important crops worldwide. They increase soil fertility due their ability to establish symbiotic associations with soil microorganisms, known as rhizobia, capable of fixing nitrogen from the atmosphere. However, they are frequently exposed to abiotic stress conditions in particular drought. Such adverse conditions impair the biological nitrogen fixation (BNF) and depend largely on the legume. Therefore, two peanut cultivars with contrasting tolerance to drought, namely the more tolerant EC-98 and the sensitive Granoleico, were investigated to elucidate the relative contribution of BNF to the tolerance to drought. The tolerant cultivar EC-98 sustained growth and BNF similar to the control condition despite the reduced water potential and photosynthesis, suggesting the functioning of distinct metabolic pathways that contributed to enhance the tolerance. The biochemical and metabolomics approaches revealed that nodules from the tolerant cultivar accumulated trehalose, proline and gamma-aminobutyric acid (GABA), metabolites with known function in protecting against drought stress. The amide metabolism was severely affected in nodules from the sensitive cultivar Granoleico as revealed by the low content of asparagine and glutamine in the drought stressed plants. The sensitive cultivar upon rehydration was unable to re-establish a metabolism similar to well-watered plants. This was evidenced by the low level of metabolites and, transcripts and specific activities of enzymes from the carbon (sucrose synthase) and nitrogen (glutamine synthetase) metabolism which decreased below the values of control plants. Therefore, the increased content of metabolites with protective functions under drought stress likely is crucial for the full restoration upon rehydration. Smaller changes of drought stress-related metabolites in nodule are another trait that contributes to the effective control of BNF in the tolerant peanut cultivar (EC-98). Copyright © 2017 Elsevier B.V. All rights reserved.
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Thao, Nguyen Phuong; Thu, Nguyen Binh Anh; Hoang, Xuan Lan Thi; Van Ha, Chien; Tran, Lam-Son Phan
2013-01-01
The plant-specific NAC transcription factors play important roles in plant response to drought stress. Here, we have compared the expression levels of a subset of GmNAC genes in drought-tolerant DT51 and drought-sensitive MTD720 under both normal and drought stress conditions aimed at identifying correlation between GmNAC expression levels and drought tolerance degree, as well as potential GmNAC candidates for genetic engineering. The expression of 23 selected dehydration-responsive GmNACs was assessed in both stressed and unstressed root tissues of DT51 and MTD720 using real-time quantitative PCR. The results indicated that expression of GmNACs was genotype-dependent. Seven and 13 of 23 tested GmNACs showed higher expression levels in roots of DT51 in comparison with MTD720 under normal and drought stress conditions, respectively, whereas none of them displayed lower transcript levels under any conditions. This finding suggests that the higher drought tolerance of DT51 might be positively correlated with the higher induction of the GmNAC genes during water deficit. The drought-inducible GmNAC011 needs to be mentioned as its transcript accumulation was more than 76-fold higher in drought-stressed DT51 roots relative to MTD720 roots. Additionally, among the GmNAC genes examined, GmNAC085, 092, 095, 101 and 109 were not only drought-inducible but also more highly up-regulated in DT51 roots than in that of MTD720 under both treatment conditions. These data together suggest that GmNAC011, 085, 092, 095, 101 and 109 might be promising candidates for improvement of drought tolerance in soybean by biotechnological approaches. PMID:24322442
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Long-term droughtiness and drought tolerance of eastern US forests over five decades
Matthew P. Peters; Louis R. Iverson; Stephen N. Matthews
2015-01-01
Droughts can influence forest composition directly by limiting water or indirectly by intensifying other stressors that affect establishment, growth, and mortality. Using community assemblages of eastern US tree species and drought tolerance characteristics assessed from literature, we examine recent drought conditions in relation to the spatial distribution of species...
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Adee, Eric; Roozeboom, Kraig; Balboa, Guillermo R.; Schlegel, Alan; Ciampitti, Ignacio A.
2016-01-01
The potential benefit of drought-tolerant (DT) corn (Zea mays L.) hybrids may depend on drought intensity, duration, crop growth stage (timing), and the array of drought tolerance mechanisms present in selected hybrids. We hypothesized that corn hybrids containing DT traits would produce more consistent yields compared to non-DT hybrids in the presence of drought stress. The objective of this study was to define types of production environments where DT hybrids have a yield advantage compared to non-DT hybrids. Drought tolerant and non-DT hybrid pairs of similar maturity were planted in six site-years with different soil types, seasonal evapotranspiration (ET), and vapor pressure deficit (VPD), representing a range of macro-environments. Irrigation regimes and seeding rates were used to create several micro-environments within each macro-environment. Hybrid response to the range of macro and micro-environmental stresses were characterized in terms of water use efficiency, grain yield, and environmental index. Yield advantage of DT hybrids was positively correlated with environment ET and VPD. Drought tolerant hybrids yielded 5 to 7% more than non-DT hybrids in high and medium ET environments (>430 mm ET), corresponding to seasonal VPD greater than 1200 Pa. Environmental index analysis confirmed that DT hybrids were superior in stressful environments. Yield advantage for DT hybrids appeared as yield dropped below 10.8 Mg ha-1 and averaged as much as 0.6–1 Mg ha-1 at the low yield range. Hybrids with DT technology can offer a degree of buffering against drought stress by minimizing yield reduction, but also maintaining a comparable yield potential in high yielding environments. Further studies should focus on the physiological mechanisms presented in the commercially available corn drought tolerant hybrids. PMID:27790237
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Markesteijn, Lars; Poorter, Lourens; Bongers, Frans; Paz, Horacio; Sack, Lawren
2011-07-01
Plant hydraulic architecture has been studied extensively, yet we know little about how hydraulic properties relate to species' life history strategies, such as drought and shade tolerance. The prevailing theories seem contradictory. We measured the sapwood (K(s) ) and leaf (K(l) ) hydraulic conductivities of 40 coexisting tree species in a Bolivian dry forest, and examined associations with functional stem and leaf traits and indices of species' drought (dry-season leaf water potential) and shade (juvenile crown exposure) tolerance. Hydraulic properties varied across species and between life-history groups (pioneers vs shade-tolerant, and deciduous vs evergreen species). In addition to the expected negative correlation of K(l) with drought tolerance, we found a strong, negative correlation between K(l) and species' shade tolerance. Across species, K(s) and K(l) were negatively correlated with wood density and positively with maximum vessel length. Consequently, drought and shade tolerance scaled similarly with hydraulic properties, wood density and leaf dry matter content. We found that deciduous species also had traits conferring efficient water transport relative to evergreen species. Hydraulic properties varied across species, corresponding to the classical trade-off between hydraulic efficiency and safety, which for these dry forest trees resulted in coordinated drought and shade tolerance across species rather than the frequently hypothesized trade-off. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.
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Killi, Dilek; Bussotti, Filippo; Raschi, Antonio; Haworth, Matthew
2017-02-01
Heat and drought stress frequently occur together, however, their impact on plant growth and photosynthesis (P N ) is unclear. The frequency, duration and severity of heat and drought stress events are predicted to increase in the future, having severe implications for agricultural productivity and food security. To assess the impact on plant gas exchange, physiology and morphology we grew drought tolerant and sensitive varieties of C3 sunflower (Helianthus annuus) and C4 maize (Zea mays) under conditions of elevated temperature for 4 weeks prior to the imposition of water deficit. The negative impact of temperature on P N was most apparent in sunflower. The drought tolerant sunflower retained ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) activity under heat stress to a greater extent than its drought sensitive counterpart. Maize exhibited no varietal difference in response to increased temperature. In contrast to previous studies, where a sudden rise in temperature induced an increase in stomatal conductance (G s ), we observed no change or a reduction in G s with elevated temperature, which alongside lower leaf area mitigated the impact of drought at the higher temperature. The drought tolerant sunflower and maize varieties exhibited greater investment in root-systems, allowing greater uptake of the available soil water. Elevated temperatures associated with heat-waves will have profound negative impacts on crop growth in both sunflower and maize, but the deleterious effect on P N was less apparent in the drought tolerant sunflower and both maize varieties. As C4 plants generally exhibit water use efficiency (WUE) and resistance to heat stress, selection on the basis of tolerance to heat and drought stress would be more beneficial to the yields of C3 crops cultivated in drought prone semi-arid regions. © 2016 Scandinavian Plant Physiology Society.
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Wang, Yu; Cai, Shuyu; Yin, Lingling; Shi, Kai; Xia, Xiaojian; Zhou, Yanhong; Yu, Jingquan; Zhou, Jie
2015-01-01
Autophagy plays critical roles in plant responses to stress. In contrast to the wealth of information concerning the core process of plant autophagosome assembly, our understanding of the regulation of autophagy is limited. In this study, we demonstrated that transcription factor HsfA1a played a critical role in tomato tolerance to drought stress, in part through its positive role in induction of autophagy under drought stress. HsfA1a expression was induced by drought stress. Virus-induced HsfA1a gene silencing reduced while its overexpression increased plant drought tolerance based on both symptoms and membrane integrity. HsfA1a-silenced plants were more sensitive to endogenous ABA-mediated stomatal closure, while its overexpression lines were resistant under drought stress, indicating that phytohormone ABA did not play a major role in HsfA1a-induced drought tolerance. On the other hand, HsfA1a-silenced plants increased while its overexpression decreased the levels of insoluble proteins which were highly ubiquitinated under drought stress. Furthermore, drought stress induced numerous ATGs expression and autophagosome formation in wild-type plants. The expression of ATG10 and ATG18f, and the formation of autophagosomes were compromised in HsfA1a-silenced plants but were enhanced in HsfA1a-overexpressing plants. Both electrophoretic mobility shift assay and chromatin immunoprecipitation coupled with qPCR analysis revealed that HsfA1a bound to ATG10 and ATG18f gene promoters. Silencing of ATG10 and ATG18f reduced HsfA1a-induced drought tolerance and autophagosome formation in plants overexpressing HsfA1a. These results demonstrate that HsfA1a induces drought tolerance by activating ATG genes and inducing autophagy, which may promote plant survival by degrading ubiquitinated protein aggregates under drought stress. PMID:26649940
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Jia, Licong; Yang, Guohong; Xu, Xinzhi; Zhai, Hong; He, Shaozhen; Li, Junxia; Dai, Xiaodong; Qin, Na; Zhu, Cancan
2018-01-01
Previously, we obtained the sweetpotato somatic hybrid KT1 from a cross between sweetpotato (Ipomoea batatas (L.) Lam.) cv. Kokei No. 14 and its drought-tolerant wild relative I. triloba L. KT1 not only inherited the thick storage root characteristic of Kokei No. 14 but also the drought-tolerance trait of I. triloba L. The aim of this study was to explore the molecular mechanism of the drought tolerance of KT1. Four-week-old in vitro-grown plants of KT1, Kokei No. 14, and I. triloba L. were subjected to a simulated drought stress treatment (30% PEG6000) for 0, 6, 12 and 24 h. Total RNA was extracted from samples at each time point, and then used for transcriptome sequencing. The gene transcript profiles of KT1 and its parents were compared to identify differentially expressed genes, and drought-related modules were screened by a weighted gene co-expression network analysis. The functions of ABI-like protein and Ca2+-ATPase, two proteins screened from the cyan and light yellow modules, were analyzed in terms of their potential roles in drought tolerance in KT1 and its parents. These analyses of the drought responses of KT1 and its somatic donors at the transcriptional level provide new annotations for the molecular mechanism of drought tolerance in the somatic hybrid KT1 and its parents. PMID:29466419
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Vinod; Naik, Bhojaraja K.; Chand, Suresh; Deshmukh, Rupesh; Mallick, Niharika; Singh, Sanjay; Singh, Nagendra Kumar; Tomar, S. M. S.
2016-01-01
Water availability is a major limiting factor for wheat (Triticum aestivum L.) production in rain-fed agricultural systems worldwide. Root architecture is important for water and nutrition acquisition for all crops, including wheat. A set of 158 diverse wheat genotypes of Australian (72) and Indian (86) origin were studied for morpho-agronomical traits in field under irrigated and drought stress conditions during 2010–11 and 2011-12.Out of these 31 Indian wheat genotypes comprising 28 hexaploid (Triticum aestivum L.) and 3 tetraploid (T. durum) were characterized for root traits at reproductive stage in polyvinyl chloride (PVC) pipes. Roots of drought tolerant genotypes grew upto137cm (C306) as compared to sensitive one of 63cm with a mean value of 94.8cm. Root architecture traits of four drought tolerant (C306, HW2004, HD2888 and NI5439) and drought sensitive (HD2877, HD2012, HD2851 and MACS2496) genotypes were also observed at 6 and 9 days old seedling stage. The genotypes did not show any significant variation for root traits except for longer coleoptiles and shoot and higher absorptive surface area in drought tolerant genotypes. The visible evaluation of root images using WinRhizo Tron root scanner of drought tolerant genotype HW2004 indicated compact root system with longer depth while drought sensitive genotype HD2877 exhibited higher horizontal root spread and less depth at reproductive stage. Thirty SSR markers were used to study genetic variation which ranged from 0.12 to 0.77 with an average value of 0.57. The genotypes were categorized into three subgroups as highly tolerant, sensitive, moderately sensitive and tolerant as intermediate group based on UPGMA cluster, STRUCTURE and principal coordinate analyses. The genotypic clustering was positively correlated to grouping based on root and morpho-agronomical traits. The genetic variability identified in current study demonstrated these traits can be used to improve drought tolerance and association mapping. PMID:27280445
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Senapati, Nimai; Stratonovitch, Pierre; Paul, Matthew J; Semenov, Mikhail A
2018-06-12
Drought stress during reproductive development could drastically reduce grain number and wheat yield, but quantitative evaluation of such effect is unknown under climate change. The objectives of this study were to a) evaluate potential yield benefits of drought tolerance during reproductive development for wheat ideotypes under climate change in Europe, and b) identify potential cultivar parameters for improvement. We used the Sirius wheat model to optimise drought tolerant (DT) and drought sensitive (DS) wheat ideotypes under future 2050 climate scenario at 13 contrasting sites, representing major wheat growing regions in Europe. Averaged over the sites, DT ideotypes achieved 13.4% greater yield compared to DS, with the double yield stability for DT. However, the performances of the ideotypes were site dependent. Mean yield of DT was 28-37% greater compared to DS in southern Europe. In contrast, no yield difference (≤ 1%) between ideotypes was found in north-western Europe. An intermediate yield benefit of 10-23% was found due to drought tolerance in central and eastern Europe. We conclude that tolerance to drought stress during reproductive development is important for high yield potentials and greater yield stability of wheat under climate change in Europe.
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Drought responses of flood-tolerant trees in Amazonian floodplains
Parolin, Pia; Lucas, Christine; Piedade, Maria Teresa F.; Wittmann, Florian
2010-01-01
Background Flood-tolerant tree species of the Amazonian floodplain forests are subjected to an annual dry period of variable severity imposed when low river-water levels coincide with minimal precipitation. Although the responses of these species to flooding have been examined extensively, their responses to drought, in terms of phenology, growth and physiology, have been neglected hitherto, although some information is found in publications that focus on flooding. Scope The present review examines the dry phase of the annual flooding cycle. It consolidates existing knowledge regarding responses to drought among adult trees and seedlings of many Amazonian floodplain species. Main Findings Flood-tolerant species display variable physiological responses to dry periods and drought that indicate desiccation avoidance, such as reduced photosynthetic activity and reduced root respiration. However, tolerance and avoidance strategies for drought vary markedly among species. Drought can substantially decrease growth, biomass and photosynthetic activity among seedlings in field and laboratory studies. When compared with the responses to flooding, drought can impose higher seedling mortality and slower growth rates, especially among evergreen species. Results indicate that tolerance and avoidance strategies for drought vary markedly between species. Both seedling recruitment and photosynthetic activity are affected by drought, Conclusions For many species, the effects of drought can be as important as flooding for survival and growth, particularly at the seedling phase of establishment, ultimately influencing species composition. In the context of climate change and predicted decreases in precipitation in the Amazon Basin, the effects of drought on plant physiology and species distribution in tropical floodplain forest ecosystems should not be overlooked. PMID:19880423
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Wright, J K; Williams, M; Starr, G; McGee, J; Mitchell, R J
2013-02-01
Environmental controls on carbon dynamics operate at a range of interacting scales from the leaf to landscape. The key questions of this study addressed the influence of water and nitrogen (N) availability on Pinus palustris (Mill.) physiology and primary productivity across leaf and canopy scales, linking the soil-plant-atmosphere (SPA) model to leaf and stand-scale flux and leaf trait/canopy data. We present previously unreported ecophysiological parameters (e.g. V(cmax) and J(max)) for P. palustris and the first modelled estimates of its annual gross primary productivity (GPP) across xeric and mesic sites and under extreme drought. Annual mesic site P. palustris GPP was ∼23% greater than at the xeric site. However, at the leaf level, xeric trees had higher net photosynthetic rates, and water and light use efficiency. At the canopy scale, GPP was limited by light interception (canopy level), but co-limited by nitrogen and water at the leaf level. Contrary to expectations, the impacts of an intense growing season drought were greater at the mesic site. Modelling indicated a 10% greater decrease in mesic GPP compared with the xeric site. Xeric P. palustris trees exhibited drought-tolerant behaviour that contrasted with mesic trees' drought-avoidance behaviour. © 2012 Blackwell Publishing Ltd.
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Kim, Soo Jin; Kim, Woo Taek
2013-08-19
AtATL78 is an Arabidopsis RING E3 ubiquitin ligase. RT-PCR and promoter-GUS assays revealed that AtATL78 was up-regulated by cold stress and down-regulated by drought. AtATL78 was localized at the plasma-membrane. Suppression of AtATL78 increased tolerance to cold stress but decreased tolerance to drought. Our data suggests that AtATL78 is a negative regulator of cold stress response and a positive regulator of drought stress response in Arabidopsis. These results further suggest that AtATL78 plays opposing roles in cold and drought stress responses. Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
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Nilsen, Erik T; Freeman, Joshua; Grene, Ruth; Tokuhisa, James
2014-01-01
The development of water stress resistant lines of commercial tomato by breeding or genetic engineering is possible, but will take considerable time before commercial varieties are available for production. However, grafting commercial tomato lines on drought resistant rootstock may produce drought tolerant commercial tomato lines much more rapidly. Due to changing climates and the need for commercial production of vegetables in low quality fields there is an urgent need for stress tolerant commercial lines of vegetables such as tomato. In previous observations we identified a scion root stock combination ('BHN 602' scion grafted onto 'Jjak Kkung' rootstock hereafter identified as 602/Jjak) that had a qualitative drought-tolerance phenotype when compared to the non-grafted line. Based on this initial observation, we studied photosynthesis and vegetative above-ground growth during mild-drought for the 602/Jjak compared with another scion-rootstock combination ('BHN 602' scion grafted onto 'Cheong Gang' rootstock hereafter identified as 602/Cheong) and a non-grafted control. Overall above ground vegetative growth was significantly lower for 602/Jjak in comparison to the other plant lines. Moreover, water potential reduction in response to mild drought was significantly less for 602/Jjak, yet stomatal conductance of all plant-lines were equally inhibited by mild-drought. Light saturated photosynthesis of 602/Jjak was less affected by low water potential than the other two lines as was the % reduction in mesophyll conductance. Therefore, the Jjak Kkung rootstock caused aboveground growth reduction, water conservation and increased photosynthetic tolerance of mild drought. These data show that different rootstocks can change the photosynthetic responses to drought of a high yielding, commercial tomato line. Also, this rapid discovery of one scion-rootstock combination that provided mild-drought tolerance suggests that screening more scion-rootstock combination for stress tolerance may rapidly yield commercially viable, stress tolerant lines of tomato.
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Li, Zhou; Peng, Yan; Huang, Bingru
2018-05-31
Gamma-aminobutyric acid (GABA) may play a positive role in regulating plant tolerance to drought or heat stress. The objectives of this study were to investigate the physiological effects of GABA on tolerance of creeping bentgrass ( Agrostis stolonifera ) to heat and drought stress and to determine whether enhanced heat and drought tolerance due to GABA treatment was associated with the up-regulation of selected genes and transcriptional factors involved in stress protection. Creeping bentgrass (cultivar "Penncross") plants were treated with 0.5 mM GABA or water (untreated control) as a foliar spray and were subsequently exposed to heat stress (35/30 °C, day/night), drought stress by withholding irrigation, or non-stress conditions in controlled-environment growth chambers. Exogenous application of GABA significantly improved plant tolerance to heat and drought stress, as reflected by increased leaf water content, cell membrane stability, and chlorophyll content. The analysis of gene transcript level revealed that exogenous GABA up-regulated the expression of ABF3 , POD , APX , HSP90 , DHN3 , and MT1 during heat stress and the expression of CDPK26 , MAPK1 , ABF3 , WRKY75 , MYB13 , HSP70 , MT1 , 14-3-3 , and genes ( SOD , CAT , POD , APX , MDHAR , DHAR , and GR ) encoding antioxidant enzymes during drought stress. The up-regulation of the aforementioned stress-protective genes and transcriptional factors could contribute to improved heat and drought tolerance in creeping bentgrass.
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Mapping QTLs for drought tolerance in a SEA 5 x AND 277 common bean cross with SSRs and SNP markers.
Briñez, Boris; Perseguini, Juliana Morini Küpper Cardoso; Rosa, Juliana Santa; Bassi, Denis; Gonçalves, João Guilherme Ribeiro; Almeida, Caléo; Paulino, Jean Fausto de Carvalho; Blair, Matthew Ward; Chioratto, Alisson Fernando; Carbonell, Sérgio Augusto Morais; Valdisser, Paula Arielle Mendes Ribeiro; Vianello, Rosana Pereira; Benchimol-Reis, Luciana Lasry
2017-01-01
The common bean is characterized by high sensitivity to drought and low productivity. Breeding for drought resistance in this species involves genes of different genetic groups. In this work, we used a SEA 5 x AND 277 cross to map quantitative trait loci associated with drought tolerance in order to assess the factors that determine the magnitude of drought response in common beans. A total of 438 polymorphic markers were used to genotype the F8 mapping population. Phenotyping was done in two greenhouses, one used to simulate drought and the other to simulate irrigated conditions. Fourteen traits associated with drought tolerance were measured to identify the quantitative trait loci (QTLs). The map was constructed with 331 markers that covered all 11 chromosomes and had a total length of 1515 cM. Twenty-two QTLs were discovered for chlorophyll, leaf and stem fresh biomass, leaf biomass dry weight, leaf temperature, number of pods per plant, number of seeds per plant, seed weight, days to flowering, dry pod weight and total yield under well-watered and drought (stress) conditions. All the QTLs detected under drought conditions showed positive effects of the SEA 5 allele. This study provides a better understanding of the genetic inheritance of drought tolerance in common bean.
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Transcriptome analysis of lentil (Lens culinaris Medikus) in response to seedling drought stress.
Singh, Dharmendra; Singh, Chandan Kumar; Taunk, Jyoti; Tomar, Ram Sewak Singh; Chaturvedi, Ashish Kumar; Gaikwad, Kishor; Pal, Madan
2017-02-27
Drought stress is one of the most harmful abiotic stresses in crop plants. As a moderately drought tolerant crop, lentil is a major crop in rainfed areas and a suitable candidate for drought stress tolerance research work. Screening for drought tolerance stress under hydroponic conditions at seedling stage with air exposure is an efficient technique to select genotypes with contrasting traits. Transcriptome analysis provides valuable resources, especially for lentil, as here the information on complete genome sequence is not available. Hence, the present studies were carried out. This study was undertaken to understand the biochemical mechanisms and transcriptome changes involved in imparting adaptation to drought stress at seedling stage in drought-tolerant (PDL-2) and drought-sensitive (JL-3) cultivars. Among different physiological and biochemical parameters, a significant increase was recorded in proline, glycine betaine contents and activities of SOD, APX and GPX in PDL-2 compared to JL-3while chlorophyll, RWC and catalase activity decreased significantly in JL-3. Transcriptome changes between the PDL-2 and JL-3 under drought stress were evaluated using Illumina HiSeq 2500 platform. Total number of bases ranged from 5.1 to 6.7 Gb. Sequence analysis of control and drought treated cDNA libraries of PDL-2 and JL-3 produced 74032, 75500, 78328 and 81523 contigs, respectively with respective N50 value of 2011, 2008, 2000 and 1991. Differential gene expression of drought treated genotypes along with their controls revealed a total of 11,435 upregulated and 6,934 downregulated transcripts. For functional classification of DEGs, KEGG pathway annotation analysis extracted a total of 413 GO annotation terms where 176 were within molecular process, 128 in cellular and 109 in biological process groups. The transcriptional profiles provide a foundation for deciphering the underlying mechanism for drought tolerance in lentil. Transcriptional regulation, signal transduction and secondary metabolism in two genotypes revealed significant differences at seedling stage under severe drought. Our finding suggests role of candidate genes for improving drought tolerance in lentil.
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Villar-Salvador, Pedro; Peñuelas, Juan L; Jacobs, Douglass F
2013-02-01
Functional attributes determine the survival and growth of planted seedlings in reforestation projects. Nitrogen (N) and water are important resources in the cultivation of forest species, which have a strong effect on plant functional traits. We analyzed the influence of N nutrition on drought acclimation of Pinus pinea L. seedlings. Specifically, we addressed if high N fertilization reduces drought and frost tolerance of seedlings and whether drought hardening reverses the effect of high N fertilization on stress tolerance. Seedlings were grown under two N fertilization regimes (6 and 100 mg N per plant) and subjected to three drought-hardening levels (well-watered, moderate and strong hardening). Water relations, gas exchange, frost damage, N concentration and growth at the end of the drought-hardening period, and survival and growth of seedlings under controlled xeric and mesic outplanting conditions were measured. Relative to low-N plants, high-N plants were larger, had higher stomatal conductance (27%), residual transpiration (11%) and new root growth capacity and closed stomata at higher water potential. However, high N fertilization also increased frost damage (24%) and decreased plasmalemma stability to dehydration (9%). Drought hardening reversed to a great extent the reduction in stress tolerance caused by high N fertilization as it decreased frost damage, stomatal conductance and residual transpiration by 21, 31 and 24%, respectively, and increased plasmalemma stability to dehydration (8%). Drought hardening increased tissue non-structural carbohydrates and N concentration, especially in high-fertilized plants. Frost damage was positively related to the stability of plasmalemma to dehydration (r = 0.92) and both traits were negatively related to the concentration of reducing soluble sugars. No differences existed between moderate and strong drought-hardening treatments. Neither N nutrition nor drought hardening had any clear effect on seedling performance under xeric outplanting conditions. However, fertilization increased growth under mesic conditions, whereas drought hardening decreased growth. We conclude that drought hardening and N fertilization applied under typical container nursery operational conditions exert opposite effects on the physiological stress tolerance of P. pinea seedlings. While drought hardening increases overall stress tolerance, N nutrition reduces it and yet has no effect on the drought acclimation capacity of seedlings.
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Drought-Responsive Mechanisms in Plant Leaves Revealed by Proteomics.
Wang, Xiaoli; Cai, Xiaofeng; Xu, Chenxi; Wang, Quanhua; Dai, Shaojun
2016-10-18
Plant drought tolerance is a complex trait that requires a global view to understand its underlying mechanism. The proteomic aspects of plant drought response have been extensively investigated in model plants, crops and wood plants. In this review, we summarize recent proteomic studies on drought response in leaves to reveal the common and specialized drought-responsive mechanisms in different plants. Although drought-responsive proteins exhibit various patterns depending on plant species, genotypes and stress intensity, proteomic analyses show that dominant changes occurred in sensing and signal transduction, reactive oxygen species scavenging, osmotic regulation, gene expression, protein synthesis/turnover, cell structure modulation, as well as carbohydrate and energy metabolism. In combination with physiological and molecular results, proteomic studies in leaves have helped to discover some potential proteins and/or metabolic pathways for drought tolerance. These findings provide new clues for understanding the molecular basis of plant drought tolerance.
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Drought-Responsive Mechanisms in Plant Leaves Revealed by Proteomics
Wang, Xiaoli; Cai, Xiaofeng; Xu, Chenxi; Wang, Quanhua; Dai, Shaojun
2016-01-01
Plant drought tolerance is a complex trait that requires a global view to understand its underlying mechanism. The proteomic aspects of plant drought response have been extensively investigated in model plants, crops and wood plants. In this review, we summarize recent proteomic studies on drought response in leaves to reveal the common and specialized drought-responsive mechanisms in different plants. Although drought-responsive proteins exhibit various patterns depending on plant species, genotypes and stress intensity, proteomic analyses show that dominant changes occurred in sensing and signal transduction, reactive oxygen species scavenging, osmotic regulation, gene expression, protein synthesis/turnover, cell structure modulation, as well as carbohydrate and energy metabolism. In combination with physiological and molecular results, proteomic studies in leaves have helped to discover some potential proteins and/or metabolic pathways for drought tolerance. These findings provide new clues for understanding the molecular basis of plant drought tolerance. PMID:27763546
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USDA-ARS?s Scientific Manuscript database
Terminal and intermittent drought limits dry bean production worldwide.The Buster/Roza mapping population (140 F7:9 RILs) has been screened for drought tolerance across multiple years/locations. In 2011 and 2012 the RILs were tested for terminal drought response at two locations: Othello, WA and Sco...
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Tripathy, Manas Kumar; Tiwari, Budhi Sagar; Reddy, Malireddy K; Deswal, Renu; Sopory, Sudhir K
2017-01-01
In this work, we have overexpressed a vesicle trafficking protein, Rab7, from a stress-tolerant plant, Pennisetum glaucum, in a high-yielding but stress-sensitive rice variety Pusa Basmati-1 (PB-1). The transgenic rice plants were tested for tolerance against salinity and drought stress. The transgenic plants showed considerable tolerance at the vegetative stage against both salinity (200 mM NaCl) and drought stress (up to 12 days after withdrawing water). The protection against salt and drought stress may be by regulating Na + ion homeostasis, as the transgenic plants showed altered expression of multiple transporter genes, including OsNHX1, OsNHX2, OsSOS1, OsVHA, and OsGLRs. In addition, decreased generation and maintenance of lesser reactive oxygen species (ROS), with maintenance of chloroplast grana and photosynthetic machinery was observed. When evaluated for reproductive growth, 89-96 % of seed setting was maintained in transgenic plants during drought stress; however, under salt stress, a 33-53 % decrease in seed setting was observed. These results indicate that PgRab7 overexpression in rice confers differential tolerance at the seed setting stage during salinity and drought stress and could be a favored target for raising drought-tolerant crops.
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Development of DArT-based PCR markers for selecting drought-tolerant spring barley.
Fiust, Anna; Rapacz, Marcin; Wójcik-Jagła, Magdalena; Tyrka, Mirosław
2015-08-01
The tolerance of spring barley (Hordeum vulgare L.) cultivars to spring drought is an important agronomic trait affecting crop yield and quality in Poland. Therefore, breeders require new molecular markers to select plants with lower spring drought susceptibility. With the advent of genomic selection technology, simple molecular tools may still be applicable to screen material for markers of the most important traits and in-depth genome scanning. In previous studies, diversity arrays technology (DArT)-based genetic maps were constructed for F2 populations of Polish fodder and malt barley elite breeding lines, and 15 and 18 quantitative trait loci (QTLs) related to spring drought tolerance were identified, respectively. In this paper, we show the results of a conversion of 30 DArT markers corresponding to 11 QTLs into simple sequence repeat (SSR) and sequence tagged site (STS) markers. Twenty-two polymorphic markers were obtained, including 13 DArT-based SSRs. Additionally, 31 SSR markers, located in close proximity to the DArT markers, were selected from the GrainGenes database and tested. Further analyses of 24 advanced breeding lines with different drought tolerances confirmed that five out of the 30 converted markers, as well as three out of the 31 additional SSR markers, were effective in marker-assisted selection for drought tolerance. The possible function of clones related to these markers in drought tolerance is discussed.
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Bartlett, Megan K; Scoffoni, Christine; Sack, Lawren
2012-05-01
Increasing drought is one of the most critical challenges facing species and ecosystems worldwide, and improved theory and practices are needed for quantification of species tolerances. Leaf water potential at turgor loss, or wilting (π(tlp) ), is classically recognised as a major physiological determinant of plant water stress response. However, the cellular basis of π(tlp) and its importance for predicting ecological drought tolerance have been controversial. A meta-analysis of 317 species from 72 studies showed that π(tlp) was strongly correlated with water availability within and across biomes, indicating power for anticipating drought responses. We derived new equations giving both π(tlp) and relative water content at turgor loss point (RWC(tlp) ) as explicit functions of osmotic potential at full turgor (π(o) ) and bulk modulus of elasticity (ε). Sensitivity analyses and meta-analyses showed that π(o) is the major driver of π(tlp) . In contrast, ε plays no direct role in driving drought tolerance within or across species, but sclerophylly and elastic adjustments act to maintain RWC(tlp,) preventing cell dehydration, and additionally protect against nutrient, mechanical and herbivory stresses independent of drought tolerance. These findings clarify biogeographic trends and the underlying basis of drought tolerance parameters with applications in comparative assessments of species and ecosystems worldwide. © 2012 Blackwell Publishing Ltd/CNRS.
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Dani, Kaidala Ganesha Srikanta; Jamie, Ian McLeod; Prentice, Iain Colin; Atwell, Brian James
2014-01-01
Plants undergoing heat and low-CO2 stresses emit large amounts of volatile isoprenoids compared with those in stress-free conditions. One hypothesis posits that the balance between reducing power availability and its use in carbon assimilation determines constitutive isoprenoid emission rates in plants and potentially even their maximum emission capacity under brief periods of stress. To test this, we used abiotic stresses to manipulate the availability of reducing power. Specifically, we examined the effects of mild to severe drought on photosynthetic electron transport rate (ETR) and net carbon assimilation rate (NAR) and the relationship between estimated energy pools and constitutive volatile isoprenoid emission rates in two species of eucalypts: Eucalyptus occidentalis (drought tolerant) and Eucalyptus camaldulensis (drought sensitive). Isoprenoid emission rates were insensitive to mild drought, and the rates increased when the decline in NAR reached a certain species-specific threshold. ETR was sustained under drought and the ETR-NAR ratio increased, driving constitutive isoprenoid emission until severe drought caused carbon limitation of the methylerythritol phosphate pathway. The estimated residual reducing power unused for carbon assimilation, based on the energetic status model, significantly correlated with constitutive isoprenoid emission rates across gradients of drought (r2 > 0.8) and photorespiratory stress (r2 > 0.9). Carbon availability could critically limit emission rates under severe drought and photorespiratory stresses. Under most instances of moderate abiotic stress levels, increased isoprenoid emission rates compete with photorespiration for the residual reducing power not invested in carbon assimilation. A similar mechanism also explains the individual positive effects of low-CO2, heat, and drought stresses on isoprenoid emission. PMID:25139160
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Chugh, Vishal; Kaur, Narinder; Grewal, M S; Gupta, Anil K
2013-04-01
The role of oxidative stress management was evaluated in two maize (Zea mays L.) genotypes - Parkash (drought-resistant) and Paras (drought-sensitive), subjected to drought stress during reproductive stage. Alterations in their antioxidant pools - glutathione (GSH) and ascorbic acid (AsA) combined with activities of enzymes glutathione reductase (GR), ascorbate peroxidase (APX), peroxidase (POX) and catalase (CAT) involved in defense against oxidative stress and stress parameters, namely chlorophyll (Chl), hydrogen peroxide (H2O2) and malondialdehyde (MDA) were investigated in flag leaves from silk emergence till maturity. The drought caused transient increase in GR, APX, POX and CAT activities in drought-tolerant genotype (Parkash) which decreased at later stages with the extended period of drought stress. However, in Paras, drought stress caused decrease in activities of GR and CAT from initial period of stress till the end of experiment, except for POX which showed slight increase in activity. A significant increase in GSH content was observed in Parkash till 35 days after silking (DAS), whereas in Paras, GSH content remained lower than irrigated till maturity. Parkash which had higher AsA and Chl contents, also showed lower H2O2 and MDA levels than Paras under drought stress conditions. However, at the later stages, decline in antioxidant enzyme activities in Parkash due to severe drought stress led to enhanced membrane damage, as revealed by the accumulation of MDA. Our data indicated that significant activation of antioxidant system in Parkash might be responsible for its drought-tolerant behavior under drought stress and helped it to cope with the stress up to a definite period. Thus, the results indicate that antioxidant status and lipid peroxidation in flag leaves can be used as indices of drought tolerance in maize plants and also as potential biochemical targets for the crop improvement programmes to develop drought-tolerant cultivars.
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Breeding drought tolerant rice for shallow rainfed ecosystem of eastern India.
Swain, Padmini; Raman, Anitha; Singh, S P; Kumar, Arvind
2017-08-01
In shallow rainfed rice agro-ecosystems, drought stress can occur at any growth stage and can cause a significant yield reduction. During recent years, some rice varieties possessing tolerance of reproductive-stage drought stress have recently been developed. Tolerance of vegetative-stage drought stress is also required to improve rice productivity in drought-prone regions. In this study, we evaluated a set of rice breeding lines for their response to a range of different types of vegetative-stage drought stress in order to propose standardized phenotyping protocols for conducting vegetative-stage drought stress screening trials and also to identify genotypes combining tolerance of vegetative- and reproductive-stage drought stress. A soil water potential threshold of -20 kPa during the vegetative stage was identified as the target for effective selection under vegetative stage with grain yield reduction of about 50% compared to irrigated control trials. Genotypes identified as showing high yield under reproductive-stage drought stress were not necessarily the genotypes showing best performance under vegetative-stage drought stress. Genotypes IR72667-16-1-B-B-3, IR78908-126-B-2-B, and IR79970-B-47-1 showed tolerance of both vegetative-stage and reproductive-stage drought stress. For most, the genotypes that were best under vegetative stage drought or even vegetative stage + reproductive stage drought were different from the genotypes that were best under reproductive stage drought. Based on the cultivar superiority measure, IR69515-6-KKN-4-UBN-4-2-1-1-1 and IR78908-126-B-1-B were the stable genotypes (indicated by low P i ) under both irrigated control and severe vegetative stress conditions, genotypes IR83614-203-B and IR78908-80-B-3-B were stable under irrigated control conditions and moderate stress, whereas IR72667-16-1-B-B-3 was stable under both moderate and severe vegetative-stage stress conditions.
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Zang, Christian; Hartl-Meier, Claudia; Dittmar, Christoph; Rothe, Andreas; Menzel, Annette
2014-12-01
The future performance of native tree species under climate change conditions is frequently discussed, since increasingly severe and more frequent drought events are expected to become a major risk for forest ecosystems. To improve our understanding of the drought tolerance of the three common European temperate forest tree species Norway spruce, silver fir and common beech, we tested the influence of climate and tree-specific traits on the inter and intrasite variability in drought responses of these species. Basal area increment data from a large tree-ring network in Southern Germany and Alpine Austria along a climatic cline from warm-dry to cool-wet conditions were used to calculate indices of tolerance to drought events and their variability at the level of individual trees and populations. General patterns of tolerance indicated a high vulnerability of Norway spruce in comparison to fir and beech and a strong influence of bioclimatic conditions on drought response for all species. On the level of individual trees, low-growth rates prior to drought events, high competitive status and low age favored resilience in growth response to drought. Consequently, drought events led to heterogeneous and variable response patterns in forests stands. These findings may support the idea of deliberately using spontaneous selection and adaption effects as a passive strategy of forest management under climate change conditions, especially a strong directional selection for more tolerant individuals when frequency and intensity of summer droughts will increase in the course of global climate change. © 2014 John Wiley & Sons Ltd.
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NASA Astrophysics Data System (ADS)
Nche-Fambo, F. A.; Scharler, U. M.; Tirok, K.
2015-06-01
In South African estuaries, there is no knowledge on the resilience and variability in phytoplankton communities under conditions of hypersalinity, extended droughts and reverse salinity gradients. Phytoplankton composition, abundance and biomass vary with changes in environmental variables and taxa richness declines specifically under hypersaline conditions. This research thus investigated the phytoplankton community composition, its resilience and variability under highly variable and extreme environmental conditions in an estuarine lake system (Lake St. Lucia, South Africa) over one year. The lake system was characterised by a reverse salinity gradient with hypersalinity furthest from the estuarine inlet during the study period. During this study, 78 taxa were recorded: 56 diatoms, eight green algae, one cryptophyte, seven cyanobacteria and six dinoflagellates. Taxon variability and resilience depended on their ability to tolerate high salinities. Consequently, the phytoplankton communities as well as total abundance and biomass differed along the salinity gradient and over time with salinity as the main determinant. Cyanobacteria were dominant in hypersaline conditions, dinoflagellates in marine-brackish salinities, green algae and cryptophytes in lower salinities (brackish) and diatoms were abundant in marine-brackish salinities but survived in hypersaline conditions. Total abundance and biomass ranged from 3.66 × 103 to 1.11 × 109 Cells/L and 1.21 × 106 to 1.46 × 1010 pgC/L respectively, with the highest values observed under hypersaline conditions. Therefore, even under highly variable, extreme environmental conditions and hypersalinity the phytoplankton community as a whole was resilient enough to maintain a relatively high biomass throughout the study period. The resilience of few dominant taxa, such as Cyanothece, Spirulina, Protoperidinium and Nitzschia and the dominance of other common genera such as Chlamydomonas, Chroomonas, Navicula, Gyrosigma, Oxyrrhis, and Prorocentrum, provided the carbon at the base of the food web in the system and showed that even during the extended period of drought, a foundation for productivity can be provided for once conditions improve.
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Singh, Ruchi; Pandey, Neha; Naskar, Jishnu; Shirke, Pramod A
2015-03-01
Cotton is mostly cultivated under rain-fed conditions in India, thus faces frequent drought conditions during its life cycle. Drought being a major stress factor responsible for yield penalty, there has always been a high priority to generate knowledge on adaptation and tolerance of cotton. In the present study, four cotton varieties, JKC-770 and KC-2 (Gossypium hirsutum), and JKC-717 and RAHS-187(Gossypium herbaceum), were imposed to drought. Under drought condition, differential changes in physiological characters like net photosynthesis, transpiration, stomatal conductance, chlorophyll fluorescence, relative water content (RWC), and predawn water potential (ψ 0) showed a change. While proline, malondialdehyde (MDA), and glutathione-S-transferase (GST) content increased along with a concomitant change in the expression of their associated genes. Under moderate stress, tolerant varieties maintain lower ψ 0 probably due to higher proline content as compared to sensitive varieties. Cyclic electron flow (CEF) also plays an important role in tolerance under mild water stress in G. hirsutum varieties. CEF not only activates at high light but also initiates at a very low light intensity. Expression analysis of genes reveals that drought-tolerant varieties showed enhanced detoxifying mechanism by up-regulation of asparagine synthase (AS), glutathione-S-transferase (GST), and methyl glyoxalase (GlyI) genes under drought stress. Up-regulation of Δ(1)-pyrroline-5-carboxylase synthase (Δ(1)P5CS) enhanced accumulation of proline, an osmolyte, under drought in tolerant varieties. While the drought-sensitive varieties showed up-regulation of ethylene responsive factor (ERF) and down-regulation of WRKY70 responsible for senescence of the leaf which correlated well with the high rate of leaf fall in sensitive varieties under water stress.
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Phenotyping bananas for drought resistance
Ravi, Iyyakkutty; Uma, Subbaraya; Vaganan, Muthu Mayil; Mustaffa, Mohamed M.
2012-01-01
Drought has emerged as one of the major constraints in banana production. Its effects are pronounced substantially in the tropics and sub-tropics of the world due to climate change. Bananas are quite sensitive to drought; however, genotypes with “B” genome are more tolerant to abiotic stresses than those solely based on “A” genome. In particular, bananas with “ABB” genomes are more tolerant to drought and other abiotic stresses than other genotypes. A good phenotyping plan is a prerequisite for any improvement program for targeted traits. In the present article, known drought tolerant traits of other crop plants are validated in bananas with different genomic backgrounds and presented. Since, banana is recalcitrant to breeding, strategies for making hybrids between different genomic backgrounds are also discussed. Stomatal conductance, cell membrane stability (CMS), leaf emergence rate, rate of leaf senescence, RWC, and bunch yield under soil moisture deficit stress are some of the traits associated with drought tolerance. Among these stress bunch yield under drought should be given top priority for phenotyping. In the light of recently released Musa genome draft sequence, the molecular breeders may have interest in developing molecular markers for drought resistance. PMID:23443573
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NASA Astrophysics Data System (ADS)
Massanelli, J.; Meadows-McDonnell, M.; Konzelman, C.; Moon, J. B.; Kumar, A.; Thomas, J.; Pereira, A.; Naithani, K. J.
2016-12-01
Meeting agricultural water demands is becoming progressively difficult due to population growth and changes in climate. Breeding stress-resilient crops is a viable solution, as information about genetic variation and their role in stress tolerance is becoming available due to advancement in technology. In this study we screened eight diverse rice genotypes for photosynthetic capacity under greenhouse conditions. These include the Asian rice (Oryza sativa) genotypes, drought sensitive Nipponbare, and a transgenic line overexpressing the HYR gene in Nipponbare; six genotypes (Vandana, Bengal, Nagina-22, Glaberrima, Kaybonnet, Ai Chueh Ta Pai Ku) and an African rice O. glaberrima, all selected for varying levels of drought tolerance. We collected CO2 and light response curve data under well-watered and simulated drought conditions in greenhouse. From these curves we estimated photosynthesis model parameters, such as the maximum carboxylation rate (Vcmax), the maximum electron transport rate (Jmax), the maximum gross photosynthesis rate, daytime respiration (Rd), and quantum yield (f). Our results suggest that O. glaberrima and Nipponbare were the most sensitive to drought because Vcmax and Pgmax declined under drought conditions; other drought tolerant genotypes did not show significant changes in these model parameters. Our integrated approach, combining genetic information and photosynthesis modeling, shows promise to quantify drought response parameters and improve crop yield under drought stress conditions.
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Lata, Charu; Jha, Sarita; Dixit, Vivek; Sreenivasulu, Nese; Prasad, Manoj
2011-10-01
Foxtail millet (Setaria italica L.) known as a relatively drought-tolerant crop across the world is grown in arid and semi-arid regions. To the best of our knowledge, no systematic study on drought tolerance screening of foxtail millet germplasm being a drought-tolerant crop has been reported so far. To explore genetic diversity of drought-induced oxidative stress tolerance in foxtail millet, we employed lipid peroxidation measure to assess membrane integrity under stress as biochemical marker to screen 107 cultivars and classified the genotypes as highly tolerant, tolerant, sensitive, and highly sensitive. From this comprehensive screening, four cultivars showing differential response to dehydration tolerance were selected to understand the physiological and biochemical basis of tolerance mechanisms. The dehydration-tolerant cultivars (IC-403579 and Prasad) showed considerably lower levels of lipid peroxidation and electrolyte leakage as compared with dehydration-sensitive cultivars (IC-480117 and Lepakshi), indicating better cell membrane integrity in tolerant cultivars. Correspondingly, tolerant genotypes maintained higher activity of catalase (EC 1.11.1.6), ascorbate peroxidase (APX; EC 1.11.1.11), and glutathione reductase (GR; EC 1.6.4.2) across different time-course period of polyethylene glycol (PEG) treatments in comparison to sensitive ones. The above biochemical results were further validated through quantitative real-time PCR analysis of APX and GR, whose transcripts were substantially induced by PEG treatments in tolerant cultivars. These results suggest that tolerant cultivars possess wider array of antioxidant machinery with efficient ascorbate-glutathione pathway to cope with drought-induced oxidative stress.
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Quantitative trait loci associated with drought tolerance in brachypodium distachyon
USDA-ARS?s Scientific Manuscript database
The temperate wild grass Brachypodium distachyon (Brachypodium) serves as model system for studying turf and forage grasses. Brachypodium collections show diverse responses to drought stress, but little is known about the genetic mechanisms of drought tolerance of this species. The objective of this...
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NASA Astrophysics Data System (ADS)
Isaac-Renton, Miriam; Montwé, David; Hamann, Andreas; Spiecker, Heinrich; Cherubini, Paolo; Treydte, Kerstin
2016-04-01
Choosing drought-tolerant seed sources for reforestation may help adapt forests to climate change. By combining dendroecological growth analysis with a long-term provenance trial, we assessed growth and drought tolerance of different populations of a wide-ranging conifer, lodgepole pine (Pinus contorta). This experimental design simulated a climate warming scenario through southward seed transfer, and an exceptional drought also occurred in 2002. We felled over 500 trees, representing 23 seed sources, which were grown for 32 years at three warm, dry sites in southern British Columbia, Canada. Northern populations showed poor growth and drought tolerance. These seed sources therefore appear to be especially at risk under climate change. Before recommending assisted migration of southern seeds towards the north, however, it is important to understand the physiological mechanisms underlying these responses. We combine functional wood anatomy with a dual-isotope approach to evaluate these mechanisms to drought response.
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Tripathi, Prateek
2014-01-01
Abstract Drought is one of the major constraints in crop production and has an effect on a global scale. In order to improve crop production, it is necessary to understand how plants respond to stress. A good understanding of regulatory mechanisms involved in plant responses during drought will enable researchers to explore and manipulate key regulatory points in order to enhance stress tolerance in crops. Transcription factors (TFs) have played an important role in crop improvement from the dawn of agriculture. TFs are therefore good candidates for genetic engineering to improve crop tolerance to drought because of their role as master regulators of clusters of genes. Many families of TFs, such as CCAAT, homeodomain, bHLH, NAC, AP2/ERF, bZIP, and WRKY have members that may have the potential to be tools for improving crop tolerance to drought. In this review, the roles of TFs as tools to improve drought tolerance in crops are discussed. The review also focuses on current strategies in the use of TFs, with emphasis on several major TF families in improving drought tolerance of major crops. Finally, many promising transgenic lines that may have improved drought responses have been poorly characterized and consequently their usefulness in the field is uncertain. New advances in high-throughput phenotyping, both greenhouse and field based, should facilitate improved phenomics of transgenic lines. Systems biology approaches should then define the underlying changes that result in higher yields under water stress conditions. These new technologies should help show whether manipulating TFs can have effects on yield under field conditions. PMID:25118806
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Global analysis of plasticity in turgor loss point, a key drought tolerance trait.
Bartlett, Megan K; Zhang, Ya; Kreidler, Nissa; Sun, Shanwen; Ardy, Rico; Cao, Kunfang; Sack, Lawren
2014-12-01
Many species face increasing drought under climate change. Plasticity has been predicted to strongly influence species' drought responses, but broad patterns in plasticity have not been examined for key drought tolerance traits, including turgor loss or 'wilting' point (πtlp ). As soil dries, plants shift πtlp by accumulating solutes (i.e. 'osmotic adjustment'). We conducted the first global analysis of plasticity in Δπtlp and related traits for 283 wild and crop species in ecosystems worldwide. Δπtlp was widely prevalent but moderate (-0.44 MPa), accounting for 16% of post-drought πtlp. Thus, pre-drought πtlp was a considerably stronger predictor of post-drought πtlp across species of wild plants. For cultivars of certain crops Δπtlp accounted for major differences in post-drought πtlp. Climate was correlated with pre- and post-drought πtlp, but not Δπtlp. Thus, despite the wide prevalence of plasticity, πtlp measured in one season can reliably characterise most species' constitutive drought tolerances and distributions relative to water supply. © 2014 John Wiley & Sons Ltd/CNRS.
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Exploring traditional aus-type rice for metabolites conferring drought tolerance.
Casartelli, Alberto; Riewe, David; Hubberten, Hans Michael; Altmann, Thomas; Hoefgen, Rainer; Heuer, Sigrid
2018-01-25
Traditional varieties and landraces belonging to the aus-type group of rice (Oryza sativa L.) are known to be highly tolerant to environmental stresses, such as drought and heat, and are therefore recognized as a valuable genetic resource for crop improvement. Using two aus-type (Dular, N22) and two drought intolerant irrigated varieties (IR64, IR74) an untargeted metabolomics analysis was conducted to identify drought-responsive metabolites associated with tolerance. The superior drought tolerance of Dular and N22 compared with the irrigated varieties was confirmed by phenotyping plants grown to maturity after imposing severe drought stress in a dry-down treatment. Dular and N22 did not show a significant reduction in grain yield compared to well-watered control plants, whereas the intolerant varieties showed a significant reduction in both, total spikelet number and grain yield. The metabolomics analysis was conducted with shoot and root samples of plants at the tillering stage at the end of the dry-down treatment. The data revealed an overall higher accumulation of N-rich metabolites (amino acids and nucleotide-related metabolites allantoin and uridine) in shoots of the tolerant varieties. In roots, the aus-type varieties were characterised by a higher reduction of metabolites representative of glycolysis and the TCA cycle, such as malate, glyceric acid and glyceric acid-3-phosphate. On the other hand, the oligosaccharide raffinose showed a higher fold increase in both, shoots and roots of the sensitive genotypes. The data further showed that, for certain drought-responsive metabolites, differences between the contrasting rice varieties were already evident under well-watered control conditions. The drought tolerance-related metabolites identified in the aus-type varieties provide a valuable set of protective compounds and an entry point for assessing genetic diversity in the underlying pathways for developing drought tolerant rice and other crops.
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Henry, Amelia; Wehler, Regina; Grondin, Alexandre; Franke, Rochus; Quintana, Marinell
2016-01-01
Background and Aims Root hydraulic limitations (i.e. intra-plant restrictions to water movement) may be related to crop performance under drought, and groupings in the hydraulic function of drought-tolerant and drought-susceptible rice (Oryza sativa) varieties have been previously reported. This study aimed to better understand the environmental and physiological relationships with rice root hydraulics under drought. Methods Xylem sap bleeding rates in the field (gsap g–1 shoot) were measured on seasonal and diurnal time frames, during which time environmental conditions were monitored and physiological measurements were conducted. Complementary experiments on the effects of vapour pressure deficit (VPD) on root hydraulic conductivity and on transpiration rates of de-rooted tillers were conducted in growth chambers. Key Results The diurnal effects on bleeding rate were more closely related to irradiance than VPD, and VPD effects on root hydraulic conductivity measured on 21-day-old plants were due to effects on plant growth including root surface area, maximum root depth and root:shoot ratio. Leaf osmotic potential was related to the grouping of drought-tolerant and drought-susceptible varieties in rice root hydraulics, and these groupings were independent of differences in phenology. Low single-tiller bleeding rates were observed under high evapo-transpirational demand, higher bleeding rates were observed at more negative leaf osmotic potentials in drought-susceptible varieties, and drought-tolerant and susceptible varieties differed in the VPD-induced increase in transpiration rates of de-rooted tillers. Low root suberin amounts in some of the drought-susceptible varieties may have resulted in higher ion transport, as evidenced by higher sap K+ concentration and higher bleeding rates in those varieties. Conclusions These results provide evidence of the environmental effects on shoots that can influence root hydraulics. The consistent groupings of drought-tolerant and susceptible varieties suggest that traits affecting plant osmotic status may regulate root hydraulic response to drought in rice. PMID:27192712
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Mapping QTLs for drought tolerance in a SEA 5 x AND 277 common bean cross with SSRs and SNP markers
Briñez, Boris; Perseguini, Juliana Morini Küpper Cardoso; Rosa, Juliana Santa; Bassi, Denis; Gonçalves, João Guilherme Ribeiro; Almeida, Caléo; Paulino, Jean Fausto de Carvalho; Blair, Matthew Ward; Chioratto, Alisson Fernando; Carbonell, Sérgio Augusto Morais; Valdisser, Paula Arielle Mendes Ribeiro; Vianello, Rosana Pereira; Benchimol-Reis, Luciana Lasry
2017-01-01
Abstract The common bean is characterized by high sensitivity to drought and low productivity. Breeding for drought resistance in this species involves genes of different genetic groups. In this work, we used a SEA 5 x AND 277 cross to map quantitative trait loci associated with drought tolerance in order to assess the factors that determine the magnitude of drought response in common beans. A total of 438 polymorphic markers were used to genotype the F8 mapping population. Phenotyping was done in two greenhouses, one used to simulate drought and the other to simulate irrigated conditions. Fourteen traits associated with drought tolerance were measured to identify the quantitative trait loci (QTLs). The map was constructed with 331 markers that covered all 11 chromosomes and had a total length of 1515 cM. Twenty-two QTLs were discovered for chlorophyll, leaf and stem fresh biomass, leaf biomass dry weight, leaf temperature, number of pods per plant, number of seeds per plant, seed weight, days to flowering, dry pod weight and total yield under well-watered and drought (stress) conditions. All the QTLs detected under drought conditions showed positive effects of the SEA 5 allele. This study provides a better understanding of the genetic inheritance of drought tolerance in common bean. PMID:29064511
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NASA Astrophysics Data System (ADS)
Pleban, J. R.; Mackay, D. S.; Aston, T.; Ewers, B. E.; Wienig, C.
2013-12-01
Quantifying the drought tolerance of crop species and genotypes is essential in order to predict how water stress may impact agricultural productivity. As climate models predict an increase in both frequency and severity of drought corresponding plant hydraulic and biochemical models are needed to accurately predict crop drought tolerance. Drought can result in cavitation of xylem conduits and related loss of plant hydraulic conductivity. This study tested the hypothesis that a model incorporating a plants vulnerability to cavitation would best assess drought tolerance in Brassica rapa. Four Brassica genotypes were subjected to drought conditions at a field site in Laramie, WY. Concurrent leaf gas exchange, volumetric soil moisture content and xylem pressure measurements were made during the drought period. Three models were used to access genotype specific drought tolerance. All 3 models rely on the Farquhar biochemical/biophysical model of leaf level photosynthesis, which is integrated into the Terrestrial Regional Ecosystem Exchange Simulator (TREES). The models differ in how TREES applies the environmental driving data and plant physiological mechanisms; specifically how water availability at the site of photosynthesis is derived. Model 1 established leaf water availability from a modeled soil moisture content; Model 2 input soil moisture measurements directly to establish leaf water availability; Model 3 incorporated the Sperry soil-plant transport model, which calculates flows and pressure along the soil-plant water transport pathway to establish leaf water availability. This third model incorporated measured xylem pressures thus constraining leaf water availability via genotype specific vulnerability curves. A multi-model intercomparison was made using a Bayesian approach, which assessed the interaction between uncertainty in model results and data. The three models were further evaluated by assessing model accuracy and complexity via deviance information criteria (DIC). Results suggest that model 1 was unable to model soil moisture accurately and thus did not effectively characterize drought tolerance. Models 2 and 3 were both effective at characterizing drought tolerance; model 3 preformed best in genotypes with the highest vulnerability to cavitation. By identifying through both Bayesian and DIC analyses models that best characterize drought tolerance future investigations into the interaction between crop productivity and water use can be informed by hypothesis testing using models prior to experimentation.
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Selection System for the "Stay-green" Drought Tolerance Trait in Sorghum Germplasm
USDA-ARS?s Scientific Manuscript database
Post-flowering drought tolerance is an essential trait for increasing cereal production in Mediterranean climates. Current methodologies for identifying the nonsenescent (stay-green) trait require the right intensity of drought stress at the right developmental stage to visually evaluate lines in t...
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USDA-ARS?s Scientific Manuscript database
Temperature and drought are major abiotic limitations to crop productivity worldwide. While abiotic stress physiology research has focused primarily on fully expanded leaves, no studies have investigated photosynthetic tolerance to concurrent drought and high temperature during leaf ontogeny. To add...
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Expression of Finger Millet EcDehydrin7 in Transgenic Tobacco Confers Tolerance to Drought Stress.
Singh, Rajiv Kumar; Singh, Vivek Kumar; Raghavendrarao, Sanagala; Phanindra, Mullapudi Lakshmi Venkata; Venkat Raman, K; Solanke, Amolkumar U; Kumar, Polumetla Ananda; Sharma, Tilak Raj
2015-09-01
One of the critical alarming constraints for agriculture is water scarcity. In the current scenario, global warming due to climate change and unpredictable rainfall, drought is going to be a master player and possess a big threat to stagnating gene pool of staple food crops. So it is necessary to understand the mechanisms that enable the plants to cope with drought stress. In this study, effort was made to prospect the role of EcDehydrin7 protein from normalized cDNA library of drought tolerance finger millet in transgenic tobacco. Biochemical and molecular analyses of T0 transgenic plants were done for stress tolerance. Leaf disc assay, seed germination test, dehydration assay, and chlorophyll estimation showed EcDehydrin7 protein directly link to drought tolerance. Northern and qRT PCR analyses shows relatively high expression of EcDehydrin7 protein compare to wild type. T0 transgenic lines EcDehydrin7(11) and EcDehydrin7(15) shows superior expression among all lines under study. In summary, all results suggest that EcDehydrin7 protein has a remarkable role in drought tolerance and may be used for sustainable crop breeding program in other food crops.
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Identification of drought-responsive genes in roots of upland rice (Oryza sativa L)
Rabello, Aline R; Guimarães, Cléber M; Rangel, Paulo HN; da Silva, Felipe R; Seixas, Daniela; de Souza, Emanuel; Brasileiro, Ana CM; Spehar, Carlos R; Ferreira, Márcio E; Mehta, Ângela
2008-01-01
Background Rice (Oryza sativa L.) germplasm represents an extraordinary source of genes that control traits of agronomic importance such as drought tolerance. This diversity is the basis for the development of new cultivars better adapted to water restriction conditions, in particular for upland rice, which is grown under rainfall. The analyses of subtractive cDNA libraries and differential protein expression of drought tolerant and susceptible genotypes can contribute to the understanding of the genetic control of water use efficiency in rice. Results Two subtractive libraries were constructed using cDNA of drought susceptible and tolerant genotypes submitted to stress against cDNA of well-watered plants. In silico analysis revealed 463 reads, which were grouped into 282 clusters. Several genes expressed exclusively in the tolerant or susceptible genotypes were identified. Additionally, proteome analysis of roots from stressed plants was performed and 22 proteins putatively associated to drought tolerance were identified by mass spectrometry. Conclusion Several genes and proteins involved in drought-response, as well as genes with no described homologs were identified. Genes exclusively expressed in the tolerant genotype were, in general, related to maintenance of turgor and cell integrity. In contrast, in the susceptible genotype, expression of genes involved in protection against cell damage was not detected. Several protein families identified in the proteomic analysis were not detected in the cDNA analysis. There is an indication that the mechanisms of susceptibility to drought in upland rice are similar to those of lowland varieties. PMID:18922162
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Drought coping strategies in cotton: increased crop per drop.
Ullah, Abid; Sun, Heng; Yang, Xiyan; Zhang, Xianlong
2017-03-01
The growth and yield of many crops, including cotton, are affected by water deficit. Cotton has evolved drought specific as well as general morpho-physiological, biochemical and molecular responses to drought stress, which are discussed in this review. The key physiological responses against drought stress in cotton, including stomata closing, root development, cellular adaptations, photosynthesis, abscisic acid (ABA) and jasmonic acid (JA) production and reactive oxygen species (ROS) scavenging, have been identified by researchers. Drought stress induces the expression of stress-related transcription factors and genes, such as ROS scavenging, ABA or mitogen-activated protein kinases (MAPK) signalling genes, which activate various drought-related pathways to induce tolerance in the plant. It is crucial to elucidate and induce drought-tolerant traits via quantitative trait loci (QTL) analysis, transgenic approaches and exogenous application of substances. The current review article highlights the natural as well as engineered drought tolerance strategies in cotton. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.
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Creating Drought- and Salt-Tolerant Crops by Overexpressing a Vacuolar Pyrophosphatase Gene
USDA-ARS?s Scientific Manuscript database
Increased expression of an Arabidopsis vacuolar pyrophosphatase gene, AVP1, leads to increased drought and salt tolerance in transgenic plants, which has been demonstrated in laboratory and field conditions. The molecular mechanism of AVP1-mediated drought resistance is likely due to increased proto...
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Crop response of drought tolerant and conventional maize hybrids in a semi-arid environment
USDA-ARS?s Scientific Manuscript database
In the Central and Southern High Plains Regions, corn (Zea mays L.) is an important commodity for livestock feed. However, limited water resources and drought conditions can hinder corn production. Drought tolerant (DT) corn hybrids could help stabilize yields under water-limited conditions, though ...
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USDA-ARS?s Scientific Manuscript database
Drought tolerant (DT) maize (Zea mays L.) hybrids have potential to increase yield under drought conditions. However, little information is known about the physiological determinations of yield in DT hybrids. Our objective was to assess radiation use efficiency (RUE), biomass production, and yield ...
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Wei, Jiguang; Li, Caihong; Li, Yong; Jiang, Gaoming; Cheng, Guanglei; Zheng, Yanhai
2013-01-01
Drought is a common stress limiting crops growth and productivities worldwide. Water deficit may increase cellular membrane permeability, resulting in K outflow. Internal K starvation may disorder plant metabolism and limit plant growth. However, it is seldom reported about the effects of external K on drought tolerance of contrasting wheat cultivars. A hydroponics experiment was carried out in a non-controlled greenhouse. Seedlings of drought-tolerant SN16 and intolerant JM22 were simultaneously treated by five levels of K2CO3 (0, 2.5, 5, 7.5, 10 mM) and two levels of PEG6000 (0, 20%) for 7 days. External K2CO3 significantly increased shoot K(+) content, water potential, chlorophyll content as well as gas exchange, but decreased electrolyte leakage (EL) and MDA content in both cultivars under PEG6000 stress. Antioxidant enzymes activities were up-regulated by PEG6000 while external K2CO3 reduced those changes. Molecular basis was explained by measuring the expression levels of antioxidant enzymes related genes. Shoot and root biomass were also increased by K2CO3 supply under drought stress. Although adequate K2CO3 application enhanced plant growth for both cultivars under drought stress, SN16 was better than JM22 due to its high drought tolerance. Adequate external K may effectively protect winter wheat from drought injuries. We conclude that drought-tolerant wheat combined with adequate external K supply may be a promising strategy for better growth in arid and semi-arid regions.
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Bartwal, Arti; Pande, Anjali; Sharma, Priyadarshini; Arora, Sandeep
2016-07-01
Drought is a major form of abiotic stress leading to lower crop productivity. Experiment was carried out for selecting the most tolerant genotype among six different genotypes of finger millet under drought stress. Seeds of six finger millet genotypes were sown in pots and grown for 35 days. After this period, drought was induced by withholding watering for stressed plants while control plants were watered regularly for comparison. Among all six different varieties of finger millet screened (PR202, PES400, PRM6107, VL283, VL328 and VL149) under varying intensities of drought stress,PRM6107 and PR202 showed highest stress tolerance by limiting excessive accumulation of reactive oxygen species (ROS) through activation of ROS scavenging antioxidative enzymes. A 200% increase in ascorbate content was recorded in PRM6107 and PR202, while in other varieties limited increase in ascorbate content was observed. Maximum decrease in chlorophyll content was observed in VL328 (83%) while least drop was observed in VL149 (65%). Relative water content indicated that PR202 was able to retain maximum water content under stress, as it recorded least drop in relative water content (55%), contributing to its better survival under stress. In conclusion finger millet genotypes PRM6107 and PR202 possessed maximum drought tolerance potential and thus may be used for allele mining of drought tolerant genes, which can further be employed for the development of more drought stress tolerant staple crops using biotechnological approach.
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Dose-dependent response of Trichoderma harzianum in improving drought tolerance in rice genotypes.
Pandey, Veena; Ansari, Mohammad W; Tula, Suresh; Yadav, Sandep; Sahoo, Ranjan K; Shukla, Nandini; Bains, Gurdeep; Badal, Shail; Chandra, Subhash; Gaur, A K; Kumar, Atul; Shukla, Alok; Kumar, J; Tuteja, Narendra
2016-05-01
This study demonstrates a dose-dependent response of Trichoderma harzianum Th-56 in improving drought tolerance in rice by modulating proline, SOD, lipid peroxidation product and DHN / AQU transcript level, and the growth attributes. In the present study, the effect of colonization of different doses of T. harzianum Th-56 strain in rice genotypes were evaluated under drought stress. The rice genotypes treated with increasing dose of T. harzianum strain Th-56 showed better drought tolerance as compared with untreated control plant. There was significant change in malondialdehyde, proline, higher superoxide dismutase level, plant height, total dry matter, relative chlorophyll content, leaf rolling, leaf tip burn, and the number of scorched/senesced leaves in T. harzianum Th-56 treated rice genotypes under drought stress. This was corroborated with altered expression of aquaporin and dehydrin genes in T. harzianum Th-56 treated rice genotypes. The present findings suggest that a dose of 30 g/L was the most effective in improving drought tolerance in rice, and its potential exploitation will contribute to the advancement of rice genotypes to sustain crop productivity under drought stress. Interaction studies of T. harzianum with three aromatic rice genotypes suggested that PSD-17 was highly benefitted from T. harzianum colonization under drought stress.
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Systemic nature of drought-tolerance in common bean.
Montero-Tavera, Víctor; Ruiz-Medrano, Roberto; Xoconostle-Cázares, Beatriz
2008-09-01
The response to drought at the physiological and molecular levels was studied in two common bean varieties with contrasting susceptibility to drought stress. A number of genes were found to be upregulated in the tolerant variety Pinto Villa relative to the susceptible cultivar, Carioca. The products of these genes fell in different functional categories. Further analyses of selected genes, consisting of their spatial differential expression and in situ mRNA accumulation patterns displayed interesting profiles. The drought-tolerant variety displayed a more developed root vasculature in drought conditions, when compared to the susceptible tropical bean Carioca. The in situ localization of three selected genes indicated the accumulation of their corresponding mRNAs in companion cells, sieve tubes and in developing phloem, suggesting that these, and/or the encoded proteins could constitute phloem-mobile signals. Indeed, a number of transcripts that are induced in response to water deficit accumulate in the phloem in other plant species, suggesting a general phenomenon. Moreover, the analysis of drought stress in plant varieties with contrasting tolerance to such stimulus will help to determine the role of differential expression of specific genes in response to such phenomenon, as well as other biochemical, morphological and physiological features in both cultivars.Drought-tolerant plants likely evolved a system that would allow them to maintain its vascular tissue integrity under stress. A functional phloem would then still function in the transmission of long-range signals, important for the systemic adaptation to the stress. It is expected that plants showing increased tolerance to abiotic stress, such as drought, are able to better protect their conductive tissues. This general strategy might help such plants evolve under stress conditions and colonize successfully new habitats.
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Yu, Yanwen; Yang, Dexin; Zhou, Shirong; Gu, Juntao; Wang, Fengru; Dong, Jingao; Huang, Rongfeng
2017-01-01
Drought is an important factor limiting plant development and crop production. Dissecting the factors involved in this process is the key for enhancement of plant tolerance to drought stress by genetic approach. Here, we evaluated the regulatory function of a novel rice ethylene response factor (ERF) OsERF109 in drought stress. Expression of OsERF109 was rapidly induced by stress and phytohormones. Subcellular localization and transactivation assay demonstrated that OsERF109 was localized in nucleus and possessed transactivation activity. Transgenic plants overexpressing (OE) and knockdown with RNA interfering (RI) OsERF109 exhibited significantly reduced and improved drought resistance, respectively, indicating that OsERF109 negatively regulates drought resistance in rice. Furthermore, measurement by gas chromatography showed that ethylene contents were less in OE while more in RI lines than these in wild types, supporting the data of drought tolerance and water loss in transgenic lines. Quantitative real-time PCR analysis also proved the regulation of OsERF109 in the expression of OSACS6, OSACO2, and OsERF3, which have been identified to play important roles in ethylene biosynthesis. Based on these results, our data evidence that OsERF109 regulates drought resistance by affecting the ethylene biosynthesis in rice. Overall, our study reveals the negative role of OsERF109 in ethylene biosynthesis and drought tolerance in rice.
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Bao, Gegen; Zhuo, Chunliu; Qian, Chunmei; Xiao, Ting; Guo, Zhenfei; Lu, Shaoyun
2016-01-01
Abscisic acid (ABA) regulates plant adaptive responses to various environmental stresses, while L-ascorbic acid (AsA) that is also named vitamin C is an important antioxidant and involves in plant stress tolerance and the immune system in domestic animals. Transgenic tobacco (Nicotiana tabacum L.) and stylo [Stylosanthes guianensis (Aublet) Swartz], a forage legume, plants co-expressing stylo 9-cis-epoxycarotenoid dioxygenase (SgNCED1) and yeast D-arabinono-1,4-lactone oxidase (ALO) genes were generated in this study, and tolerance to drought and chilling was analysed in comparison with transgenic tobacco overexpressing SgNCED1 or ALO and the wild-type plants. Compared to the SgNCED1 or ALO transgenic plants, in which only ABA or AsA levels were increased, both ABA and AsA levels were increased in transgenic tobacco and stylo plants co-expressing SgNCED1 and ALO genes. Compared to the wild type, an enhanced drought tolerance was observed in SgNCED1 transgenic tobacco plants with induced expression of drought-responsive genes, but not in ALO plants, while an enhanced chilling tolerance was observed in ALO transgenic tobaccos with induced expression of cold-responsive genes, but not in SgNCED1 plants. Co-expression of SgNCED1 and ALO genes resulted in elevated tolerance to both drought and chilling in transgenic tobacco and stylo plants with induced expression of both drought and cold-responsive genes. Our result suggests that co-expression of SgNCED1 and ALO genes is an effective way for use in forage plant improvement for increased tolerance to drought and chilling and nutrition quality. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.
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Casaretto, José A; El-Kereamy, Ashraf; Zeng, Bin; Stiegelmeyer, Suzy M; Chen, Xi; Bi, Yong-Mei; Rothstein, Steven J
2016-04-29
Plant response mechanisms to heat and drought stresses have been considered in strategies for generating stress tolerant genotypes, but with limited success. Here, we analyzed the transcriptome and improved tolerance to heat stress and drought of maize plants over-expressing the OsMYB55 gene. Over-expression of OsMYB55 in maize decreased the negative effects of high temperature and drought resulting in improved plant growth and performance under these conditions. This was evidenced by the higher plant biomass and reduced leaf damage exhibited by the transgenic lines compared to wild type when plants were subjected to individual or combined stresses and during or after recovery from stress. A global transcriptomic analysis using RNA sequencing revealed that several genes induced by heat stress in wild type plants are constitutively up-regulated in OsMYB55 transgenic maize. In addition, a significant number of genes up-regulated in OsMYB55 transgenic maize under control or heat treatments have been associated with responses to abiotic stresses including high temperature, dehydration and oxidative stress. The latter is a common and major consequence of imposed heat and drought conditions, suggesting that this altered gene expression may be associated with the improved stress tolerance in these transgenic lines. Functional annotation and enrichment analysis of the transcriptome also pinpoint the relevance of specific biological processes for stress responses. Our results show that expression of OsMYB55 can improve tolerance to heat stress and drought in maize plants. Enhanced expression of stress-associated genes may be involved in OsMYB55-mediated stress tolerance. Possible implications for the improved tolerance to heat stress and drought of OsMYB55 transgenic maize are discussed.
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Qin, Na; Xu, Weigang; Hu, Lin; Li, Yan; Wang, Huiwei; Qi, Xueli; Fang, Yuhui; Hua, Xia
2016-11-01
Enhancing drought tolerance of crops has been a great challenge in crop improvement. Here, we report the maize phosphoenolpyruvate carboxylase (PEPC) gene was able to confer drought tolerance and increase grain yield in transgenic wheat (Triticum aestivum L.) plants. The improved of drought tolerance was associated with higher levels of proline, soluble sugar, soluble protein, and higher water use efficiency. The transgenic wheat plants had also a more extensive root system as well as increased photosynthetic capacity during stress treatments. The increased grain yield of the transgenic wheat was contributed by improved biomass, larger spike and grain numbers, and heavier 1000-grain weight under drought-stress conditions. Under non-stressed conditions, there were no significant increases in these of the measured traits except for photosynthetic rate when compared with parental wheat. Proteomic research showed that the expression levels of some proteins, including chlorophyll A-B binding protein and pyruvate, phosphate dikinase, which are related to photosynthesis, PAP fibrillin, which is involved in cytoskeleton synthesis, S-adenosylmethionine synthetase, which catalyzes methionine synthesis, were induced in the transgenic wheat under drought stress. Additionally, the expression of glutamine synthetase, which is involved in ammonia assimilation, was induced by drought stress in the wheat. Our study shows that PEPC can improve both stress tolerance and grain yield in wheat, demonstrating the efficacy of PEPC in crop improvement.
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Salgado-Negret, Beatriz; Canessa, Rafaella; Valladares, Fernando; Armesto, Juan J; Pérez, Fernanda
2015-01-01
Climate change and fragmentation are major threats to world forests. Understanding how functional traits related to drought tolerance change across small-scale, pronounced moisture gradients in fragmented forests is important to predict species' responses to these threats. In the case of Aextoxicon punctatum, a dominant canopy tree in fog-dependent rain forest patches in semiarid Chile, we explored how the magnitude, variability and correlation patterns of leaf and xylem vessel traits and hydraulic conductivity varied across soil moisture (SM) gradients established within and among forest patches of different size, which are associated with differences in tree establishment and mortality patterns. Leaf traits varied across soil-moisture gradients produced by fog interception. Trees growing at drier leeward edges showed higher leaf mass per area, trichome and stomatal density than trees from the wetter core and windward zones. In contrast, xylem vessel traits (vessels diameter and density) did not vary producing loss of hydraulic conductivity at drier leeward edges. We also detected higher levels of phenotypic integration and variability at leeward edges. The ability of A. punctatum to modify leaf traits in response to differences in SM availability established over short distances (<500 m) facilitates its persistence in contrasting microhabitats within forest patches. However, xylem anatomy showed limited plasticity, which increases cavitation risk at leeward edges. Greater patch fragmentation, together with fluctuations in irradiance and SM in small patches, could result in higher risk of drought-related tree mortality, with profound impacts on hydrological balances at the ecosystem scale.
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Salgado-Negret, Beatriz; Canessa, Rafaella; Valladares, Fernando; Armesto, Juan J.; Pérez, Fernanda
2015-01-01
Climate change and fragmentation are major threats to world forests. Understanding how functional traits related to drought tolerance change across small-scale, pronounced moisture gradients in fragmented forests is important to predict species’ responses to these threats. In the case of Aextoxicon punctatum, a dominant canopy tree in fog-dependent rain forest patches in semiarid Chile, we explored how the magnitude, variability and correlation patterns of leaf and xylem vessel traits and hydraulic conductivity varied across soil moisture (SM) gradients established within and among forest patches of different size, which are associated with differences in tree establishment and mortality patterns. Leaf traits varied across soil-moisture gradients produced by fog interception. Trees growing at drier leeward edges showed higher leaf mass per area, trichome and stomatal density than trees from the wetter core and windward zones. In contrast, xylem vessel traits (vessels diameter and density) did not vary producing loss of hydraulic conductivity at drier leeward edges. We also detected higher levels of phenotypic integration and variability at leeward edges. The ability of A. punctatum to modify leaf traits in response to differences in SM availability established over short distances (<500 m) facilitates its persistence in contrasting microhabitats within forest patches. However, xylem anatomy showed limited plasticity, which increases cavitation risk at leeward edges. Greater patch fragmentation, together with fluctuations in irradiance and SM in small patches, could result in higher risk of drought-related tree mortality, with profound impacts on hydrological balances at the ecosystem scale. PMID:26257746
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Liu, Mingxi; Chen, Jingjing; Guo, Zhenfei; Lu, Shaoyun
2017-01-01
Centipedegrass (Eremochloa ophiuroides [Munro] Hack.) is an important warm-season turfgrass species with low turf maintenance requirements. However, our knowledge on physiological adaptation of centipedegrass to drought stress is limited. Physiological responses to drought in a gamma-ray-induced mutant 22-1 as compared with two wild type (WT) lines were analyzed for understanding of drought tolerance mechanism of centipedegrass. The mutant showed an elevated drought tolerance with higher levels of relative water content, net photosynthetic rate (A) and stomatal conductance (gs) and lower levels of ion leakage and malondialdehyde (MDA) under drought stress as compared with WT plants. A showed significant correlation with gs and MDA. Higher levels of antioxidant enzymes activities, non-enzyme antioxidants, and polyamines including putrescine (Put), spermidine (Spd), and spermine (Spm) were maintained in 22-1 than in WT plants. Superoxide dismutase (SOD), catalase (CAT), ascorbate-peroxidase (APX), and glutathione reductase (GR) activities and ascorbic acid (AsA) content were significantly correlated with both Put and Spd levels, and reduced glutathione level was correlated with Put during drought stress. Exogenous application of Put, Spd, and Spm increased drought tolerance and activities of SOD, CAT, APX, and GR in WT plants. The results suggest that higher levels of polyamines and antioxidant defense system are associated with the elevated drought tolerance in 22-1, which may improve protection on photosynthesis against drought induced oxidative damage. PMID:28559909
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Villar-Salvador, Pedro; Planelles, Rosa; Oliet, Juan; Peñuelas-Rubira, Juan L; Jacobs, Douglass F; González, Magdalena
2004-10-01
Drought stress is the main cause of mortality of holm oak (Quercus ilex L.) seedlings in forest plantations. We therefore assessed if drought hardening, applied in the nursery at the end of the growing season, enhanced the drought tolerance and transplanting performance of holm oak seedlings. Seedlings were subjected to three drought hardening intensities (low, moderate and severe) for 2.5 and 3.5 months, and compared with control seedlings. At the end of the hardening period, water relations, gas exchange and morphological attributes were determined, and survival and growth under mesic and xeric transplanting conditions were assessed. Drought hardening increased drought tolerance primarily by affecting physiological traits, with no effect on shoot/root ratio or specific leaf mass. Drought hardening reduced osmotic potential at saturation and at the turgor loss point, stomatal conductance, residual transpiration (RT) and new root growth capacity (RGC), but enhanced cell membrane stability. Among treated seedlings, the largest response occurred in seedlings subjected to moderate hardening. Severe hardening reduced shoot soluble sugar concentration and increased shoot starch concentration. Increasing the duration of hardening had no effect on water relations but reduced shoot mineral and starch concentrations. Variation in cell membrane stability, RT and RGC were negatively related to osmotic adjustment. Despite differences in drought tolerance, no differences in mortality and relative growth rate were observed between hardening treatments when the seedlings were transplanted under either mesic or xeric conditions.
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Hepworth, Christopher; Doheny-Adams, Timothy; Hunt, Lee; Cameron, Duncan D; Gray, Julie E
2015-10-01
Manipulation of stomatal density was investigated as a potential tool for enhancing drought tolerance or nutrient uptake. Drought tolerance and soil water retention were assessed using Arabidopsis epidermal patterning factor mutants manipulated to have increased or decreased stomatal density. Root nutrient uptake via mass flow was monitored under differing plant watering regimes using nitrogen-15 ((15) N) isotope and mass spectrometry. Plants with less than half of their normal complement of stomata, and correspondingly reduced levels of transpiration, conserve soil moisture and are highly drought tolerant but show little or no reduction in shoot nitrogen concentrations especially when water availability is restricted. By contrast, plants with over twice the normal density of stomata have a greater capacity for nitrogen uptake, except when water availability is restricted. We demonstrate the possibility of producing plants with reduced transpiration which have increased drought tolerance, with little or no loss of nutrient uptake. We demonstrate that increasing transpiration can enhance nutrient uptake when water is plentiful. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.
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Seasonal changes of whole root system conductance by a drought-tolerant grape root system.
Alsina, Maria Mar; Smart, David R; Bauerle, Taryn; de Herralde, Felicidad; Biel, Carme; Stockert, Christine; Negron, Claudia; Save, Robert
2011-01-01
The role of root systems in drought tolerance is a subject of very limited information compared with above-ground responses. Adjustments to the ability of roots to supply water relative to shoot transpiration demand is proposed as a major means for woody perennial plants to tolerate drought, and is often expressed as changes in the ratios of leaf to root area (A(L):A(R)). Seasonal root proliferation in a directed manner could increase the water supply function of roots independent of total root area (A(R)) and represents a mechanism whereby water supply to demand could be increased. To address this issue, seasonal root proliferation, stomatal conductance (g(s)) and whole root system hydraulic conductance (k(r)) were investigated for a drought-tolerant grape root system (Vitis berlandieri×V. rupestris cv. 1103P) and a non-drought-tolerant root system (Vitis riparia×V. rupestris cv. 101-14Mgt), upon which had been grafted the same drought-sensitive clone of Vitis vinifera cv. Merlot. Leaf water potentials (ψ(L)) for Merlot grafted onto the 1103P root system (-0.91±0.02 MPa) were +0.15 MPa higher than Merlot on 101-14Mgt (-1.06±0.03 MPa) during spring, but dropped by approximately -0.4 MPa from spring to autumn, and were significantly lower by -0.15 MPa (-1.43±0.02 MPa) than for Merlot on 101-14Mgt (at -1.28±0.02 MPa). Surprisingly, g(s) of Merlot on the drought-tolerant root system (1103P) was less down-regulated and canopies maintained evaporative fluxes ranging from 35-20 mmol vine(-1) s(-1) during the diurnal peak from spring to autumn, respectively, three times greater than those measured for Merlot on the drought-sensitive rootstock 101-14Mgt. The drought-tolerant root system grew more roots at depth during the warm summer dry period, and the whole root system conductance (k(r)) increased from 0.004 to 0.009 kg MPa(-1) s(-1) during that same time period. The changes in k(r) could not be explained by xylem anatomy or conductivity changes of individual root segments. Thus, the manner in which drought tolerance was conveyed to the drought-sensitive clone appeared to arise from deep root proliferation during the hottest and driest part of the season, rather than through changes in xylem structure, xylem density or stomatal regulation. This information can be useful to growers on a site-specific basis in selecting rootstocks for grape clonal material (scions) grafted to them.
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Impacts of the 2014 Drought on Vegetation Processes in the Sierra Nevada of California
NASA Astrophysics Data System (ADS)
Loik, M. E.; Wade, C. E.; Reed, C. C.
2014-12-01
Sierra Nevada snowpack provides over 60 percent of California's freshwater supplies. The drought of 2014 has been unprecedented in the state's history, and followed below-average precipitation for the hydrologic years 2012 and 2013. Record-low precipitation has resulted in minimal Sierra Nevada snow pack and runoff, and massive reductions in reservoir storage, which has triggered widespread drought adaptation measures for one of the world's largest economies. We assessed the impacts of the 2014 drought on vegetation processes in the headwaters of the Owens River, which is one of the main watersheds for the city of Los Angeles. We monitored water relations, photosynthesis, growth and Leaf Area Index of tree, shrub, herb, and grass species. In order to better understand the effects of drought, we examined responses to watering manipulations, long-term snow fences, elevation gradient analysis, and comparisons to previous wetter years. 1 April 2014 snow pack depth was 330 mm (average for 1928 - 2012 = 1344 mm, CV = 49%). Despite widespread mortality of Pinus jeffreyi saplings (mean 1.5 m tall) at 2300 m, older trees as well as saplings of Pinus contorta showed new growth. There were no significant differences in water potential (Ψ) for the two conifer species in a wet year (2006, 1 April snow depth = 2240 mm) vs. 2014. Water potential for P. contorta in 2014 was higher at 2900 m than at 2300 m but photosynthetic CO2 assimilation (A) and stomatal conductance (gs), were not different. By contrast, Ψ, A, gs, Vcmax and Jmax for the widespread shrub Artemisia tridentata increased along a gradient from 2100 m to 2900 m in 2014. Watering only significantly increased these photosynthetic parameters at the lowest, driest elevation. At the middle elevation, Leaf Area Index in 2014 was about 20% of the 2006 value for the N-fixing shrub Purshia tridentata. Results show reductions in photosynthesis and growth for some species but not others in response to the severe drought conditions of 2014. The ability to tolerate drought may be due to utilization of deep water for some species, or an ability to survive and grow on very little precipitation for other species. Incorporation of functional group survival, photosynthesis and growth responses to severe, ongoing drought stress should help to improve global models of carbon cycling.
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Soil microbiomass vary in their ability to confer drought tolerance to Arabidopsis
USDA-ARS?s Scientific Manuscript database
Helping plants cope with drought is a major agricultural issue that has been addressed by genetic improvement of crops and recently by using specific soil micro-organisms that confer drought tolerance. Here, we analyzed the effect of using co-adapted and non-co-adapted whole soil microbiomes to help...
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Phenotyping for drought tolerance of crops in the genomics era
Tuberosa, Roberto
2012-01-01
Improving crops yield under water-limited conditions is the most daunting challenge faced by breeders. To this end, accurate, relevant phenotyping plays an increasingly pivotal role for the selection of drought-resilient genotypes and, more in general, for a meaningful dissection of the quantitative genetic landscape that underscores the adaptive response of crops to drought. A major and universally recognized obstacle to a more effective translation of the results produced by drought-related studies into improved cultivars is the difficulty in properly phenotyping in a high-throughput fashion in order to identify the quantitative trait loci that govern yield and related traits across different water regimes. This review provides basic principles and a broad set of references useful for the management of phenotyping practices for the study and genetic dissection of drought tolerance and, ultimately, for the release of drought-tolerant cultivars. PMID:23049510
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Profiling of drought-responsive microRNA and mRNA in tomato using high-throughput sequencing.
Liu, Minmin; Yu, Huiyang; Zhao, Gangjun; Huang, Qiufeng; Lu, Yongen; Ouyang, Bo
2017-06-26
Abiotic stresses cause severe loss of crop production. Among them, drought is one of the most frequent environmental stresses, which limits crop growth, development and productivity. Plant drought tolerance is fine-tuned by a complex gene regulatory network. Understanding the molecular regulation of this polygenic trait is crucial for the eventual success to improve plant yield and quality. Recent studies have demonstrated that microRNAs play critical roles in plant drought tolerance. However, little is known about the microRNA in drought response of the model plant tomato. Here, we described the profiling of drought-responsive microRNA and mRNA in tomato using high-throughput next-generation sequencing. Drought stress was applied on the seedlings of M82, a drought-sensitive cultivated tomato genotype, and IL9-1, a drought-tolerant introgression line derived from the stress-resistant wild species Solanum pennellii LA0716 and M82. Under drought, IL9-1 performed superior than M82 regarding survival rate, H 2 O 2 elimination and leaf turgor maintenance. A total of four small RNA and eight mRNA libraries were constructed and sequenced using Illumina sequencing technology. 105 conserved and 179 novel microRNAs were identified, among them, 54 and 98 were differentially expressed upon drought stress, respectively. The majority of the differentially-expressed conserved microRNAs was up-regulated in IL9-1 whereas down-regulated in M82. Under drought stress, 2714 and 1161 genes were found to be differentially expressed in M82 and IL9-1, respectively, and many of their homologues are involved in plant stress, such as genes encoding transcription factor and protein kinase. Various pathways involved in abiotic stress were revealed by Gene Ontology and pathway analysis. The mRNA sequencing results indicated that most of the target genes were regulated by their corresponding microRNAs, which suggested that microRNAs may play essential roles in the drought tolerance of tomato. In this study, numerous microRNAs and mRNAs involved in the drought response of tomato were identified using high-throughput sequencing, which will provide new insights into the complex regulatory network of plant adaption to drought stress. This work will also help to exploit new players functioning in plant drought-stress tolerance.
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Hussain, Muhammad Mubashar; Rauf, Saeed; Riaz, Muhammad Asam; Al-Khayri, Jameel Muhammad; Monneveux, Philippe
2017-06-01
Drought is a major constraint for sunflower ( Helianthus annuus ) production worldwide. Drought tolerance traits have been identified in the related wild species Helianthus argophyllus . This study was initiated to develop sunflower drought-tolerant genotypes by crossing cultivated sunflower with this species and analyze drought tolerance traits in the H. annuus and H. argophyllus populations, H. annuus intraspecific hybrids, and H. annuus × H. argophyllus interspecific hybrids along with the commercial hybrid Hysun-33 under three stress regimes: exogenous application of ABA, both by foliar spray and irrigation, and 5% PEG-induced osmotic stress. H. argophyllus populations had a significantly lower leaf area and higher water-use efficiency and leaf cuticular wax content under all treatments, and maintained a higher net photosynthetic rate and stomatal conductance under osmotic stress. Small leaf area and high cuticular waxes content of the wild species were, however, not inherited in interspecific hybrids which suggested for selection in F 2 for these traits. Therefore, transgressive plants were selected in the F 2 population to establish F 3 plant progenies with silver-leafed canopy of H. argophyllus which showed higher achene yield under stress condition. These results are discussed with a view to using H. argophyllus to improve drought tolerance in cultivated sunflower.
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Hussain, Muhammad Mubashar; Rauf, Saeed; Riaz, Muhammad Asam; Al-Khayri, Jameel Muhammad; Monneveux, Philippe
2017-01-01
Drought is a major constraint for sunflower (Helianthus annuus) production worldwide. Drought tolerance traits have been identified in the related wild species Helianthus argophyllus. This study was initiated to develop sunflower drought-tolerant genotypes by crossing cultivated sunflower with this species and analyze drought tolerance traits in the H. annuus and H. argophyllus populations, H. annuus intraspecific hybrids, and H. annuus × H. argophyllus interspecific hybrids along with the commercial hybrid Hysun-33 under three stress regimes: exogenous application of ABA, both by foliar spray and irrigation, and 5% PEG-induced osmotic stress. H. argophyllus populations had a significantly lower leaf area and higher water-use efficiency and leaf cuticular wax content under all treatments, and maintained a higher net photosynthetic rate and stomatal conductance under osmotic stress. Small leaf area and high cuticular waxes content of the wild species were, however, not inherited in interspecific hybrids which suggested for selection in F2 for these traits. Therefore, transgressive plants were selected in the F2 population to establish F3 plant progenies with silver-leafed canopy of H. argophyllus which showed higher achene yield under stress condition. These results are discussed with a view to using H. argophyllus to improve drought tolerance in cultivated sunflower. PMID:28744179
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Yıldırım, Kubilay; Kaya, Zeki
2017-06-01
Drought is the major environmental problem limiting the productivity and survival of plant species. Here, previously identified three black poplar genotypes having contrasting response to drought were subjected to gradual soil water depletion in a pot trial to identify their physiological, morphological and antioxidation related adaptations. We also performed a microarray based transcriptome analyses on the leaves of genotypes by using Affymetrix poplar Genome Array containing 56,000 transcripts. Phenotypic analyses of each genotype confirmed their differential adaptations to drought that could be classified as drought escape, avoidance and tolerance. Comparative transcriptomic analysis indicated highly divergent gene expression patterns among the genotypes in response to drought and post drought re-watering (PDR). We identified 10641, 3824 and 9411 transcripts exclusively regulated in drought escape, avoidance and tolerant genotypes, respectively. The key genes involved in metabolic pathways, such as carbohydrate metabolism, photosynthesis, lipid metabolism, generation of precursor metabolites/energy, protein folding, redox homeostasis, secondary metabolic process and cell wall component biogenesis, were affected by drought stresses in the leaves of these genotypes. Transcript isoforms showed increased expression specificity in the genes coding for bark storage proteins and small heat shock proteins in drought tolerant genotype. On the other hand, drought-avoiding genotype specifically induced the transcripts annotated to the genes functional in secondary metabolite production that linked to enhanced leaf water content and growth performance under drought stress. Transcriptome profiling of drought escape genotype indicated specific regulation of the genes functional in programmed cell death and leaf senescence. Specific upregulation of GTP cyclohydrolase II and transcription factors (WRKY and ERFs) in only this genotype were associated to ROS dependent signalling pathways and gene regulation network responsible in induction of many degrading enzymes acting on cell wall carbohydrates, fatty acids and proteins under drought stress. Our findings provide new insights into the transcriptome dynamics and components of regulatory network associated with drought adaptation strategies. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
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Species-specific photorespiratory rate, drought tolerance and isoprene emission rate in plants.
Dani, K G Srikanta; Jamie, Ian M; Prentice, I Colin; Atwell, Brian J
2015-01-01
The effect of drought on plant isoprene emission varies tremendously across species and environments. It was recently shown that an increased ratio of photosynthetic electron transport rate (ETR) to net carbon assimilation rate (NAR) consistently supported increased emission under drought. In this commentary, we highlight some of the physiological aspects of drought tolerance that are central to the observed variability. We briefly discuss some of the issues that must be addressed in order to refine our understanding of plant isoprene emission response to drought and increasing global temperature.
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2013-01-01
Background Soybean is an important crop that provides valuable proteins and oils for human use. Because soybean growth and development is extremely sensitive to water deficit, quality and crop yields are severely impacted by drought stress. In the face of limited water resources, drought-responsive genes are therefore of interest. Identification and analysis of dehydration- and rehydration-inducible differentially expressed genes (DEGs) would not only aid elucidation of molecular mechanisms of stress response, but also enable improvement of crop stress tolerance via gene transfer. Using Digital Gene Expression Tag profiling (DGE), a new technique based on Illumina sequencing, we analyzed expression profiles between two soybean genotypes to identify drought-responsive genes. Results Two soybean genotypes—drought-tolerant Jindou21 and drought-sensitive Zhongdou33—were subjected to dehydration and rehydration conditions. For analysis of DEGs under dehydration conditions, 20 cDNA libraries were generated from roots and leaves at two different time points under well-watered and dehydration conditions. We also generated eight libraries for analysis under rehydration conditions. Sequencing of the 28 libraries produced 25,000–33,000 unambiguous tags, which were mapped to reference sequences for annotation of expressed genes. Many genes exhibited significant expression differences among the libraries. DEGs in the drought-tolerant genotype were identified by comparison of DEGs among treatments and genotypes. In Jindou21, 518 and 614 genes were differentially expressed under dehydration in leaves and roots, respectively, with 24 identified both in leaves and roots. The main functional categories enriched in these DEGs were metabolic process, response to stresses, plant hormone signal transduction, protein processing, and plant-pathogen interaction pathway; the associated genes primarily encoded transcription factors, protein kinases, and other regulatory proteins. The seven most significantly expressed (|log2 ratio| ≥ 8) genes— Glyma15g03920, Glyma05g02470, Glyma15g15010, Glyma05g09070, Glyma06g35630, Glyma08g12590, and Glyma11g16000—are more likely to determine drought stress tolerance. The expression patterns of eight randomly-selected genes were confirmed by quantitative RT-PCR; the results of QRT-PCR analysis agreed with transcriptional profile data for 96 out of 128 (75%) data points. Conclusions Many soybean genes were differentially expressed between drought-tolerant and drought-sensitive genotypes. Based on GO functional annotation and pathway enrichment analysis, some of these genes encoded transcription factors, protein kinases, and other regulatory proteins. The seven most significant DEGs are candidates for improving soybean drought tolerance. These findings will be helpful for analysis and elucidation of molecular mechanisms of drought tolerance; they also provide a basis for cultivating new varieties of drought-tolerant soybean. PMID:24093224
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Henry, Amelia; Wehler, Regina; Grondin, Alexandre; Franke, Rochus; Quintana, Marinell
2016-05-02
Root hydraulic limitations (i.e. intra-plant restrictions to water movement) may be related to crop performance under drought, and groupings in the hydraulic function of drought-tolerant and drought-susceptible rice (Oryza sativa) varieties have been previously reported. This study aimed to better understand the environmental and physiological relationships with rice root hydraulics under drought. Xylem sap bleeding rates in the field (g sap g -1 shoot ) were measured on seasonal and diurnal time frames, during which time environmental conditions were monitored and physiological measurements were conducted. Complementary experiments on the effects of vapour pressure deficit (VPD) on root hydraulic conductivity and on transpiration rates of de-rooted tillers were conducted in growth chambers. The diurnal effects on bleeding rate were more closely related to irradiance than VPD, and VPD effects on root hydraulic conductivity measured on 21-day-old plants were due to effects on plant growth including root surface area, maximum root depth and root:shoot ratio. Leaf osmotic potential was related to the grouping of drought-tolerant and drought-susceptible varieties in rice root hydraulics, and these groupings were independent of differences in phenology. Low single-tiller bleeding rates were observed under high evapo-transpirational demand, higher bleeding rates were observed at more negative leaf osmotic potentials in drought-susceptible varieties, and drought-tolerant and susceptible varieties differed in the VPD-induced increase in transpiration rates of de-rooted tillers. Low root suberin amounts in some of the drought-susceptible varieties may have resulted in higher ion transport, as evidenced by higher sap K + concentration and higher bleeding rates in those varieties. These results provide evidence of the environmental effects on shoots that can influence root hydraulics. The consistent groupings of drought-tolerant and susceptible varieties suggest that traits affecting plant osmotic status may regulate root hydraulic response to drought in rice. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
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Selvaraj, Michael Gomez; Ishizaki, Takuma; Valencia, Milton; Ogawa, Satoshi; Dedicova, Beata; Ogata, Takuya; Yoshiwara, Kyouko; Maruyama, Kyonoshin; Kusano, Miyako; Saito, Kazuki; Takahashi, Fuminori; Shinozaki, Kazuo; Nakashima, Kazuo; Ishitani, Manabu
2017-11-01
Drought stress has often caused significant decreases in crop production which could be associated with global warming. Enhancing drought tolerance without a grain yield penalty has been a great challenge in crop improvement. Here, we report the Arabidopsis thaliana galactinol synthase 2 gene (AtGolS2) was able to confer drought tolerance and increase grain yield in two different rice (Oryza sativa) genotypes under dry field conditions. The developed transgenic lines expressing AtGolS2 under the control of the constitutive maize ubiquitin promoter (Ubi:AtGolS2) also had higher levels of galactinol than the non-transgenic control. The increased grain yield of the transgenic rice under drought conditions was related to a higher number of panicles, grain fertility and biomass. Extensive confined field trials using Ubi:AtGolS2 transgenic lines in Curinga, tropical japonica and NERICA4, interspecific hybrid across two different seasons and environments revealed the verified lines have the proven field drought tolerance of the Ubi:AtGolS2 transgenic rice. The amended drought tolerance was associated with higher relative water content of leaves, higher photosynthesis activity, lesser reduction in plant growth and faster recovering ability. Collectively, our results provide strong evidence that AtGolS2 is a useful biotechnological tool to reduce grain yield losses in rice beyond genetic differences under field drought stress. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.
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RdreB1BI enhances drought tolerance by activating AQP-related genes in transgenic strawberry.
Gu, Xianbin; Gao, Zhihong; Yan, Yichao; Wang, Xiuyun; Qiao, Yushan; Chen, Yahua
2017-10-01
The dehydration-responsive element binding protein (DREB) family of transcription factors is associated with abiotic stress responses during plant growth and development. This study focussed on the subfamily member DREB1B, which was initially described as highly and specifically responsive to low temperature. However, here it is shown that DREB1B is not only involved in cold tolerance but also other abiotic stress tolerances, such as that of drought. To further understand the genetic improvement effects of the drought tolerance provided by RdreB1BI in transgenic strawberry, drought stress responses of transgenic plants were evaluated at the morphological, physiological, and transcriptional levels. Transactivation assays revealed that RdreB1BI could activate the FvPIP2;1 like 1 promoter. RdreB1BI transgenic plants showed enhanced drought tolerance on the basis of lower rates of electrolyte leakage (EL), higher relative water content (RWC), and less stomatal aperture as well as increased peroxidase (POD) and superoxide dismutase (SOD) activities and less malondialdehyde (MDA) accumulation. The transgenic plants also accumulated higher levels of drought-related regulatory genes and functional gene transcripts, including those of PIP, NAC, RD22, ABI, and NCED. Together, these results demonstrate that RdreB1BI plays an essential role in the regulation of the drought stress response. DREB1B transcription constitutes a useful strategy to exploit in transgenic plants for coping with abiotic stresses, at least cold and drought stresses. The approach may be helpful for genetic engineering horticultural plants to have increased environmental adaptations. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
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USDA-ARS?s Scientific Manuscript database
Nitrogen fixation of soybean is particularly vulnerable to drought, since, in most genotypes, N2 fixation activity decreases very early in the soil drying cycle. Although a few soybean genotypes, including ‘PI 471938’, have been identified that express N2 fixation tolerance of drought, it is unknown...
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Cheng, Lixiang; Wang, Yuping; He, Qiang; Li, Huijun; Zhang, Xiaojing; Zhang, Feng
2016-08-31
Drought stress is one of the most adverse environmental constraints to plant growth and productivity. Comparative proteomics of drought-tolerant and sensitive wheat genotypes is a strategy to understand the complexity of molecular mechanism of wheat in response to drought. This study attempted to extend findings regarding the potential proteomic dynamics in wheat under drought stress and to enrich the research content of drought tolerance mechanism. A comparative proteomics approach was applied to analyze proteome change of Xihan No. 2 (a drought-tolerant cultivar) and Longchun 23 (a drought-sensitive cultivar) subjected to a range of dehydration treatments (18 h, 24 h and 48 h) and rehydration treatment (R24 h) using 2-DE, respectively. Quantitative image analysis showed a total of 172 protein spots in Xihan No. 2 and 215 spots from Longchun 23 with their abundance significantly altered (p < 0.05) more than 2.5-fold. Out of these spots, a total of 84 and 64 differentially abundant proteins were identified by MALDI-TOF/TOF MS in Xihan No. 2 and Longchun 23, respectively. Most of these identified proteins were involved in metabolism, photosynthesis, defence and protein translation/processing/degradation in both two cultivars. In addition, the proteins involved in redox homeostasis, energy, transcription, cellular structure, signalling and transport were also identified. Furthermore, the comparative analysis of drought-responsive proteome allowed for the general elucidation of the major mechanisms associated with differential responses to drought of both two cultivars. These cellular processes work more cooperatively to re-establish homeostasis in Xihan No. 2 than Longchun 23. The resistance mechanisms of Xihan No. 2 mainly included changes in the metabolism of carbohydrates and amino acids as well as in the activation of more antioxidation and defense systems and in the levels of proteins involved in ATP synthesis and protein degradation/refolding. This study revealed that the levels of a number of proteins involved in various cellular processes were affected by drought stress in two wheat cultivars with different drought tolerance. The results showed that there exist specific responses to drought in Xihan No. 2 and Longchun 23. The proposed hypothetical model would explain the interaction of these identified proteins that are associated with drought-responses in two cultivars, and help in developing strategies to improve drought tolerance in wheat.
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Wang, Jianping; Wang, Pengxi; Ma, Xiao; Zhou, Meiliang; Li, Ji; Gang, Nie; Feng, Guangyan; Zhao, Junming
2017-01-01
Drought is a major abiotic stress that impairs growth and productivity of Italian ryegrass. Comparative analysis of drought responsive proteins will provide insight into molecular mechanism in Lolium multiflorum drought tolerance. Using the iTRAQ-based approach, proteomic changes in tolerant and susceptible lines were examined in response to drought condition. A total of 950 differentially accumulated proteins was found to be involved in carbohydrate metabolism, amino acid metabolism, biosynthesis of secondary metabolites, and signal transduction pathway, such as β-D-xylosidase, β-D-glucan glucohydrolase, glycerate dehydrogenase, Cobalamin-independent methionine synthase, glutamine synthetase 1a, Farnesyl pyrophosphate synthase, diacylglycerol, and inositol 1, 4, 5-trisphosphate, which might contributed to enhance drought tolerance or adaption in Lolium multiflorum. Interestingly, the two specific metabolic pathways, arachidonic acid and inositol phosphate metabolism including differentially accumulated proteins, were observed only in the tolerant lines. Cysteine protease cathepsin B, Cysteine proteinase, lipid transfer protein and Aquaporin were observed as drought-regulated proteins participating in hydrolysis and transmembrane transport. The activities of phospholipid hydroperoxide glutathione peroxidase, peroxiredoxin, dehydroascorbate reductase, peroxisomal ascorbate peroxidase and monodehydroascorbate reductase associated with alleviating the accumulation of reactive oxygen species in stress inducing environments. Our results showed that drought-responsive proteins were closely related to metabolic processes including signal transduction, antioxidant defenses, hydrolysis, and transmembrane transport. PMID:28910323
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Epigenetic responses to drought stress in rice (Oryza sativa L.).
Gayacharan; Joel, A John
2013-07-01
Cytosine methylation polymorphism plays a key role in gene regulation, mainly in expression of genes in crop plants. The differential expression of cytosine methylation over drought stress response was analyzed in rice using drought susceptible but agronomically superior lines IR 20 and CO 43, and drought tolerant genotypes PL and PMK 3 and their F1 hybrids. The parents and hybrids were subjected to two moisture regimes viz., one under drought condition and another under control condition. The cytosine methylation polymorphism in genomic DNA was quantified under both the conditions at the reproductive stage of the plant using the Methylation Sensitive Amplified Polymorphism (MSAP) technique devised by Xiong et al. (261:439-446, 1999). The results depicted that under drought condition, hyper-methylation was predominant in the drought susceptible genotypes while drought tolerant genotypes presented hypo-methylation behavior. While imposing drought, spikelet sterility per cent was positively correlated to percentage of methylation whereas, panicle length, number of seed per panicle, panicle weight, 100 seed weight, and yield/plant were negatively correlated indicating the role of epigenetic regulation in yield attributing traits in response to drought. Thus, methylation can be considered as an important epigenetic regulatory mechanism in rice plants to adapt drought situation. From this study, we speculate that the hyper- methylation may be an indicator of drought susceptibility and the hypo-methylation for drought tolerance and this methylation polymorphism can be effectively used in drought screening program.
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Dey, Avishek; Samanta, Milan Kumar; Gayen, Srimonta; Sen, Soumitra K.; Maiti, Mrinal K.
2016-01-01
Drought is one of the major limiting factors for productivity of crops including rice (Oryza sativa L.). Understanding the role of allelic variations of key regulatory genes involved in stress-tolerance is essential for developing an effective strategy to combat drought. The bZIP transcription factors play a crucial role in abiotic-stress adaptation in plants via abscisic acid (ABA) signaling pathway. The present study aimed to search for allelic polymorphism in the OsbZIP23 gene across selected drought-tolerant and drought-sensitive rice genotypes, and to characterize the new allele through overexpression (OE) and gene-silencing (RNAi). Analyses of the coding DNA sequence (CDS) of the cloned OsbZIP23 gene revealed single nucleotide polymorphism at four places and a 15-nucleotide deletion at one place. The single-copy OsbZIP23 gene is expressed at relatively higher level in leaf tissues of drought-tolerant genotypes, and its abundance is more in reproductive stage. Cloning and sequence analyses of the OsbZIP23-promoter from drought-tolerant O. rufipogon and drought-sensitive IR20 cultivar showed variation in the number of stress-responsive cis-elements and a 35-nucleotide deletion at 5’-UTR in IR20. Analysis of the GFP reporter gene function revealed that the promoter activity of O. rufipogon is comparatively higher than that of IR20. The overexpression of any of the two polymorphic forms (1083 bp and 1068 bp CDS) of OsbZIP23 improved drought tolerance and yield-related traits significantly by retaining higher content of cellular water, soluble sugar and proline; and exhibited decrease in membrane lipid peroxidation in comparison to RNAi lines and non-transgenic plants. The OE lines showed higher expression of target genes-OsRab16B, OsRab21 and OsLEA3-1 and increased ABA sensitivity; indicating that OsbZIP23 is a positive transcriptional-regulator of the ABA-signaling pathway. Taken together, the present study concludes that the enhanced gene expression rather than natural polymorphism in coding sequence of OsbZIP23 is accountable for improved drought tolerance and yield performance in rice genotypes. PMID:26959651
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Verbesina alternifolia Tolerance to the Holoparasite Cuscuta gronovii and the Impact of Drought
Evans, Bethany; Borowicz, Victoria
2013-01-01
Holoparasites are nonphotosynthetic plants that acquire all resources from hosts. The holoparasite Cuscuta gronovii is native to much of the US with a broad host range including Verbesina alternifolia, an understory perennial. Both species grow in moderate to moist soils and occur in habitats that may experience prolonged or episodic drought. We applied the Wise-Abrahamson Limiting Resource Model (LRM) developed for plant-herbivore relations to examine the effects of pattern of drought stress on tolerance of V. alternifolia to parasitism by C. gronovii. Individual plants were assigned one of six treatments that were combinations of parasite (none or addition of parasite) and drought stress (well-watered, continuously-stressed, or pulse-stressed). After pulse-stressed plants had experienced two wet-dry cycles all plants were harvested. Parasitism strongly reduced both shoot and root mass and well-watered hosts exhibited the greatest decline, indicating reduced tolerance to parasitism when water was readily available. This is consistent with the LRM if parasitism limits photosynthates available to the host. However, parasitism increased allocation to shoot and this effect did not differ between well-watered and drought-stressed plants, indicating equal tolerance. This outcome is in accord with an alternative prediction of the LRM if hosts are not carbon limited. Total pot productivity was reduced by parasitism and drought stress, and this effect was greater for pulse-stressed than for continuously-stressed hosts. We discuss the applicability of the LRM for understanding the effects of drought on tolerance to parasitism. PMID:27137396
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Knepper, Caleb; Mou, Beiquan
2015-01-01
This protocol describes a method by which a large collection of the leafy green vegetable lettuce (Lactuca sativa L.) germplasm was screened for likely drought-tolerance traits. Fresh water availability for agricultural use is a growing concern across the United States as well as many regions of the world. Short-term drought events along with regulatory intervention in the regulation of water availability coupled with the looming threat of long-term climate shifts that may lead to reduced precipitation in many important agricultural regions has increased the need to hasten the development of crops adapted for improved water use efficiency in order to maintain or expand production in the coming years. This protocol is not meant as a step-by-step guide to identifying at either the physiological or molecular level drought-tolerance traits in lettuce, but rather is a method developed and refined through the screening of thousands of different lettuce varieties. The nature of this screen is based in part on the streamlined measurements focusing on only three water-stress indicators: leaf relative water content, wilt, and differential plant growth following drought-stress. The purpose of rapidly screening a large germplasm collection is to narrow the candidate pool to a point in which more intensive physiological, molecular, and genetic methods can be applied to identify specific drought-tolerant traits in either the lab or field. Candidates can also be directly incorporated into breeding programs as a source of drought-tolerance traits. PMID:25938876
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Knepper, Caleb; Mou, Beiquan
2015-04-17
This protocol describes a method by which a large collection of the leafy green vegetable lettuce (Lactuca sativa L.) germplasm was screened for likely drought-tolerance traits. Fresh water availability for agricultural use is a growing concern across the United States as well as many regions of the world. Short-term drought events along with regulatory intervention in the regulation of water availability coupled with the looming threat of long-term climate shifts that may lead to reduced precipitation in many important agricultural regions has increased the need to hasten the development of crops adapted for improved water use efficiency in order to maintain or expand production in the coming years. This protocol is not meant as a step-by-step guide to identifying at either the physiological or molecular level drought-tolerance traits in lettuce, but rather is a method developed and refined through the screening of thousands of different lettuce varieties. The nature of this screen is based in part on the streamlined measurements focusing on only three water-stress indicators: leaf relative water content, wilt, and differential plant growth following drought-stress. The purpose of rapidly screening a large germplasm collection is to narrow the candidate pool to a point in which more intensive physiological, molecular, and genetic methods can be applied to identify specific drought-tolerant traits in either the lab or field. Candidates can also be directly incorporated into breeding programs as a source of drought-tolerance traits.
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Verkest, Aurine; Byzova, Marina; Martens, Cindy; Willems, Patrick; Verwulgen, Tom; Slabbinck, Bram; Rombaut, Debbie; Van de Velde, Jan; Vandepoele, Klaas; Standaert, Evi; Peeters, Marrit; Van Lijsebettens, Mieke; Van Breusegem, Frank; De Block, Marc
2015-08-01
To increase both the yield potential and stability of crops, integrated breeding strategies are used that have mostly a direct genetic basis, but the utility of epigenetics to improve complex traits is unclear. A better understanding of the status of the epigenome and its contribution to agronomic performance would help in developing approaches to incorporate the epigenetic component of complex traits into breeding programs. Starting from isogenic canola (Brassica napus) lines, epilines were generated by selecting, repeatedly for three generations, for increased energy use efficiency and drought tolerance. These epilines had an enhanced energy use efficiency, drought tolerance, and nitrogen use efficiency. Transcriptome analysis of the epilines and a line selected for its energy use efficiency solely revealed common differentially expressed genes related to the onset of stress tolerance-regulating signaling events. Genes related to responses to salt, osmotic, abscisic acid, and drought treatments were specifically differentially expressed in the drought-tolerant epilines. The status of the epigenome, scored as differential trimethylation of lysine-4 of histone 3, further supported the phenotype by targeting drought-responsive genes and facilitating the transcription of the differentially expressed genes. From these results, we conclude that the canola epigenome can be shaped by selection to increase energy use efficiency and stress tolerance. Hence, these findings warrant the further development of strategies to incorporate epigenetics into breeding. © 2015 American Society of Plant Biologists. All Rights Reserved.
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Alsdurf, Jacob D.; Ripley, Tayler J.; Matzner, Steven L.; Siemens, David H.
2013-01-01
Areas just across species range boundaries are often stressful, but even with ample genetic variation within and among range-margin populations, adaptation towards stress tolerance across range boundaries often does not occur. Adaptive trans-generational plasticity should allow organisms to circumvent these problems for temporary range expansion; however, range boundaries often persist. To investigate this dilemma, we drought stressed a parent generation of Boechera stricta (A.Gray) A. Löve & D. Löve, a perennial wild relative of Arabidopsis, representing genetic variation within and among several low-elevation range margin populations. Boechera stricta is restricted to higher, moister elevations in temperate regions where generalist herbivores are often less common. Previous reports indicate a negative genetic correlation (genetic tradeoff) between chemical defence allocation and abiotic stress tolerance that may prevent the simultaneous evolution of defence and drought tolerance that would be needed for range expansion. In growth chamber experiments, the genetic tradeoff became undetectable among offspring sib-families whose parents had been drought treated, suggesting that the stress-induced trans-generational plasticity may circumvent the genetic tradeoff and thus enable range expansion. However, the trans-generational effects also included a conflict between plastic responses (environmental tradeoff); offspring whose parents were drought treated were more drought tolerant, but had lower levels of glucosinolate toxins that function in defence against generalist herbivores. We suggest that either the genetic or environmental tradeoff between defence allocation and stress tolerance has the potential to contribute to range limit development in upland mustards. PMID:24307931
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MicroRNA156 improves drought stress tolerance in alfalfa (Medicago sativa) by silencing SPL13.
Arshad, Muhammad; Feyissa, Biruk A; Amyot, Lisa; Aung, Banyar; Hannoufa, Abdelali
2017-05-01
Alfalfa (Medicago sativa) is an important forage crop that is often grown in areas that frequently experience drought and water shortage. MicroRNA156 (miR156) is an emerging tool for improving various traits in plants. We tested the role of miR156d in drought response of alfalfa, and observed a significant improvement in drought tolerance of miR156 overexpression (miR156OE) alfalfa genotypes compared to the wild type control (WT). In addition to higher survival and reduced water loss, miR156OE genotypes also maintained higher stomatal conductance compared to WT during drought stress. Furthermore, we observed an enhanced accumulation of compatible solute (proline) and increased levels of abscisic acid (ABA) and antioxidants in miR156OE genotypes. Similarly, alfalfa plants with reduced expression of miR156-targeted SPL13 showed reduced water loss and enhanced stomatal conductance, chlorophyll content and photosynthetic assimilation. Several genes known to be involved in drought tolerance were differentially expressed in leaf and root of miR156 overexpression plants. Taken together, our findings reveal that miR156 improves drought tolerance in alfalfa at least partially by silencing SPL13. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.
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Zhou, Lian; Zhou, Jing; Xiong, Yuhan; Liu, Chaoxian; Wang, Jiuguang; Wang, Guoqiang; Cai, Yilin
2018-01-01
Drought and salt stress are major abiotic stress that inhibit plants growth and development, here we report a plasma membrane intrinsic protein ZmPIP1;1 from maize and identified its function in drought and salt tolerance in Arabidopsis. ZmPIP1;1 was localized to the plasma membrane and endoplasmic reticulum in maize protoplasts. Treatment with PEG or NaCl resulted in induced expression of ZmPIP1;1 in root and leaves. Constitutive overexpression of ZmPIP1;1 in transgenic Arabidopsis plants resulted in enhanced drought and salt stress tolerance compared to wild type. A number of stress responsive genes involved in cellular osmoprotection in ZmPIP1;1 overexpression plants were up-regulated under drought or salt condition. ZmPIP1;1 overexpression plants showed higher activities of reactive oxygen species (ROS) scavenging enzymes such as catalase and superoxide dismutase, lower contents of stress-induced ROS such as superoxide, hydrogen peroxide and malondialdehyde, and higher levels of proline under drought and salt stress than did wild type. ZmPIP1;1 may play a role in drought and salt stress tolerance by inducing of stress responsive genes and increasing of ROS scavenging enzymes activities, and could provide a valuable gene for further plant breeding.
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NASA Astrophysics Data System (ADS)
Mittal, Shikha; Banduni, Pooja; Mallikarjuna, Mallana G.; Rao, Atmakuri R.; Jain, Prashant A.; Dash, Prasanta K.; Thirunavukkarasu, Nepolean
2018-05-01
Drought is one of the major threats to maize production. In order to improve the production and to breed tolerant hybrids, understanding the genes and regulatory mechanisms during drought stress is important. Transcription factors (TFs) play a major role in gene regulation and many TFs have been identified in response to drought stress. In our experiment, a set of 15 major TF families comprising 1436 genes was structurally and functionally characterized using in-silico tools and a gene expression assay. All 1436 genes were mapped on 10 chromosome of maize. The functional annotation indicated the involvement of these genes in ABA signaling, ROS scavenging, photosynthesis, stomatal regulation, and sucrose metabolism. Duplication was identified as the primary force in divergence and expansion of TF families. Phylogenetic relationship was developed individually for each TF family as well as combined TF families. Phylogenetic analysis grouped the TF family of genes into TF-specific and mixed groups. Phylogenetic analysis of genes belonging to various TF families suggested that the origin of TFs occurred in the lineage of maize evolution. Gene structure analysis revealed that more number of genes were intron-rich as compared to intronless genes. Drought-responsive CRE’s such as ABREA, ABREB, DRE1 and DRECRTCOREAT have been identified. Expression and interaction analyses identified leaf-specific bZIP TF, GRMZM2G140355, as a potential contributor toward drought tolerance in maize. We also analyzed protein-protein interaction network of 269 drought-responsive genes belonging to different drought-related TFs. The information generated on structural and functional characteristics, expression and interaction of the drought-related TF families will be useful to decipher the drought tolerance mechanisms and to derive drought-tolerant genotypes in maize.
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Some Biological Hints on the Control of Heat and Mass Transfer
NASA Astrophysics Data System (ADS)
Hagiwara, Yoshimichi
This review paper explores the possibilities of the control of heat and mass transfer associated with drought tolerance and freeze tolerance. The accumulation of some metabolites, such as proline and trehalose, are effective for drought tolerance. The special microstructures on the surfaces of some plants and insects in deserts are effective for collecting moisture in the air. Methods of preserving crops will be improved by the mimetic of the drought tolerance. Calcium ions and a protein are effective for the retrieval of damaged cell membrane due to ice formation. Ice crystal growth is inhibited by some substances such as antifreeze proteins. The cryopreservation of foods and organs will be improved by the mimetic of the freeze tolerance.
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Wu, Yunqi; Mirzaei, Mehdi; Pascovici, Dana; Chick, Joel M; Atwell, Brian J; Haynes, Paul A
2016-06-30
Rice is the major staple food for more than half of world's population. As global climate changes, we are observing more floods, droughts and severe heat waves. Two rice cultivars with contrasting genetic backgrounds and levels of tolerance to drought, Nipponbare and IAC1131, were used in this study. Four-week-old seedlings of both cultivars were grown in large soil volumes and then exposed to moderate and extreme drought for 7days, followed by 3days of re-watering. Mature leaves were harvested from plants from each treatment for protein extraction and subsequent shotgun proteomic analysis, with validation of selected proteins by western blotting. Gene Ontology (GO) annotations of differentially expressed proteins provide insights into the metabolic pathways that are involved in drought stress resistance. Our data indicate that IAC1131 appears to be better able to cope with stressful conditions by upregulating a suite of stress and defence response related proteins. Nipponbare, in contrast, lacks the range of stress responses shown by the more stress tolerant variety, and responds to drought stress by initiating a partial shutdown of chlorophyll biosynthesis in an apparent attempt to preserve resources. In this study, two rice genotypes with contrasting drought tolerance were exposed to soil water deficits, and proteomic changes were observed in mature leaf laminae. Plants were well watered and then switched to conditions of either moderate drought or extreme drought followed by three days of recovery. Proteins were identified and quantified using both label-free and Tandem Mass Tag multiplexing approaches. Several biochemical pathways were significantly altered in response to water deficit. Most notably, the up-regulation of ClpD1 protease responded strongly in the drought-tolerant landrace; this protein is typically involved in heat and osmotic stress response. In contrast, porphyrin and chlorophyll biosynthesis pathways were down-regulated, indicating suppression of the photosynthetic machinery. Copyright © 2016 Elsevier B.V. All rights reserved.
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Avramova, Viktoriya; AbdElgawad, Hamada; Vasileva, Ivanina; Petrova, Alexandra S.; Holek, Anna; Mariën, Joachim; Asard, Han; Beemster, Gerrit T. S.
2017-01-01
We studied the impact of drought on growth regulation in leaves of 13 maize varieties with different drought sensitivity and geographic origins (Western Europe, Egypt, South Africa) and the inbred line B73. Combining kinematic analysis of the maize leaf growth zone with biochemical measurements at a high spatial resolution allowed us to examine the correlation between the regulation of the cellular processes cell division and elongation, and the molecular redox-regulation in response to drought. Moreover, we demonstrated differences in the response of the maize lines to mild and severe levels of water deficit. Kinematic analysis indicated that drought tolerant lines experienced less impact on leaf elongation rate due to a smaller reduction of cell production, which, in turn, was due to a smaller decrease of meristem size and number of cells in the leaf meristem. Clear differences in growth responses between the groups of lines with different geographic origin were observed in response to drought. The difference in drought tolerance between the Egyptian hybrids was significantly larger than between the European and South-African hybrids. Through biochemical analyses, we investigated whether antioxidant activity in the growth zone, contributes to the drought sensitivity differences. We used a hierarchical clustering to visualize the patterns of lipid peroxidation, H2O2 and antioxidant concentrations, and enzyme activities throughout the growth zone, in response to stress. The results showed that the lines with different geographic region used different molecular strategies to cope with the stress, with the Egyptian hybrids responding more at the metabolite level and African and the European hybrids at the enzyme level. However, drought tolerance correlated with both, higher antioxidant levels throughout the growth zone and higher activities of the redox-regulating enzymes CAT, POX, APX, and GR specifically in leaf meristems. These findings provide evidence for a link between antioxidant regulation in the leaf meristem, cell division, and drought tolerance. PMID:28210264
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Sen, Ayse; Alikamanoglu, Sema
2012-01-01
Drought is one of the major environmental stresses which greatly affect the plant growth and productivity. In the present study, various doses (0-75Gy) of gamma rays were applied to investigate the effect of radiation on shoot tip explants. It was observed that the regeneration rates and plant fresh weights decreased significantly with an increase in radiation dose. The optimal irradiation doses for mutation induction were determined at 15 and 20Gy. Afterwards, the induction of somatic mutation in sugar beet (Beta vulgaris L.) was investigated by irradiation of shoot tips with 15 and 20Gy gamma rays. Irradiated shoot tips were sub-cultured and M(1)V(1)-M(1)V(3) generations were obtained. Mutants tolerant to drought stress were selected on MS medium, supplemented with 10 and 20gl(-1) PEG6000. Of the M(1)V(3) plantlets, drought-tolerant mutants were selected. Leaf soluble proteins obtained from the control and drought-tolerant mutants were analyzed by SDS-PAGE. A total of 22 protein bands were determined and 2 of them were observed to be drought-tolerant mutants except the control. Polymorphism was also detected among the control and drought-tolerant mutants by DNA fingerprinting using ISSR markers. A total of 106 PCR fragments were amplified with 19 ISSR primers and 91 of them were polymorphic. The dendrograms were separated into two main clusters. First cluster included M8 mutant plant, which was applied 20Gy gamma radiation and regenerated on selective culture media containing 10gl(-1) PEG6000 concentration, and the second cluster was further divided into five sub-clusters. Copyright © 2012 Elsevier B.V. All rights reserved.
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Drought tolerance of sugar maple ecotypes
Richard J. Hauer; Jeffery O. Dawson
1995-01-01
Sugar maple declines periodically occur in rural and urban areas. These declines usually follow periods of below-average precipitation leading to the speculation that moisture deficiency is a primary cause of the decline. Sugar maple ecotypes with greater tolerance to drought should have greater longevity and vitality as a result of this tolerance. Sugar maple and...
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Meng, Lai-Sheng
2018-04-11
Water is crucial to plant growth and development because it serves as a medium for all cellular functions. Thus, the improvement of plant drought tolerance or water use efficiency/water uptake efficiency is important in modern agriculture. In this review, we mainly focus on new genetic factors for ameliorating drought tolerance or water use efficiency/water uptake efficiency of plants and explore the involvement of these genetic factors in the regulation of improving plant drought tolerance or water use efficiency/water uptake efficiency, which is a result of altered stomata density and improving root systems (primary root length, hair root growth, and lateral root number) and enhanced production of osmotic protectants, which is caused by transcription factors, proteinases, and phosphatases and protein kinases. These results will help guide the synthesis of a model for predicting how the signals of genetic and environmental stress are integrated at a few genetic determinants to control the establishment of either water use efficiency or water uptake efficiency. Collectively, these insights into the molecular mechanism underpinning the control of plant drought tolerance or water use efficiency/water uptake efficiency may aid future breeding or design strategies to increase crop yield.
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Hu, Longxing; Wang, Zhaolong; Du, Hongmei; Huang, Bingru
2010-01-15
Expression of dehydrin proteins may be induced or enhanced by environmental stresses that lead to cell dehydration. The objective of the this study was to investigate genetic variation in dehydrin protein accumulation in response to drought stress of whole-plants or dehydration of detached leaves and to identify dehydrins differentially expressed in bermudagrass (Cynodon spp.) genotypes differing in drought tolerance. Plants of four hybrid bermudagrass (Cynodondactylon L. xCynodontransvaalensis L.) ('Tifway', 'Tifdwarf', 'Tifeagle', 'Kan1') and four common bermudagrass (Cynodon dactylon) ('C299', 'Sportbermuda', 'H10', and 'H19') genotypes were subjected to 14d of drought stress and detached leaves of two genotypes were exposed to dehydration in growth chambers. Turf quality and leaf relative water content (RWC) decreased while electrolyte leakage (EL) increased during whole-plant drought stress for all genotypes, with more pronounced changes in each parameter for 'C299' and 'Tifeagle' than those for other genotypes ('Tifway', 'Kan 1', 'Sportbermuda', 'H10', and H19'), suggesting that the former two genotypes were more sensitive to drought stress than the other genotypes. During dehydration of detached leaves, relative water loss rate (RWL) was significantly lower in drought-tolerant 'Tifway' than in drought-sensitive 'C299'. Immunoblotting analysis indicated that no dehydrin polypeptides were detected in all genotypes under well-watered conditions. A 24-kDa polypeptide was detected in 'C299' at 6 d of drought, but not in the other genotypes. The dehydrin polypeptides of about 14-74kDa accumulated at 10d of drought stress and in a range of RWL for detached leaves, and two dehydrins (31 and 40kDa) exhibited differential accumulation in the drought-sensitive 'C299' and tolerant 'Tifway', as demonstrated by the whole-plant drought responses. The 31-kDa dehydrin polypeptide was present only in 'Tifway' and 'H19' at 10d of drought stress, and accumulated with the increasing RWL in detached leaves of 'Tifway'. The expression level of 40-kDa dehydrin polypeptides was greater in 'Tifway'' than in 'C299' at the same level of water deficit (from 10% to 65% RWL). These results indicated that the accumulation of 31- and 40-kDa dehydrins may contribute to drought or dehydration tolerance in warm-season bermudagrass.
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Fernando Pineda-García; Horacio Paz; Frederick C. Meinzer; Guillermo Angeles; Guillermo Goldstein
2015-01-01
In seasonal plant communities where water availability changes dramatically both between and within seasons, understanding the mechanisms that enable plants to exploit water pulses and to survive drought periods is crucial. By measuring rates of physiological processes, we examined the trade-off between water exploitation and drought tolerance among seedlings of trees...
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USDA-ARS?s Scientific Manuscript database
Drought and salt tolerances are complex traits and controlled by multiple genes, environmental factors and their interactions. Drought and salt stresses can result in more than 50% yield loss in Upland cotton (Gossypium hirsutum L.). G. barbadense L. (the source of Pima cotton) carries desirable tra...
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Chen, Qian; Zheng, Yan; Luo, Landi; Yang, Yongping; Hu, Xiangyang; Kong, Xiangxiang
2018-01-01
Flowering at the right time is important for the reproductive success of plants and their response to environmental stress. In Arabidopsis, a major determinant of natural variation in flowering time is FRIGIDA (FRI). In the present study, we show that overexpression of the functional FRIGIDA gene in wild-type Col background (ColFRI) positively enhances the drought tolerance by activating P5CS1 expression and promoting proline accumulation during water stress. Furthermore, no significant changes in FRI gene and protein expression levels were observed with drought treatment, whereas P5CS1 protein expression significantly increased. In contrast, vernalization treatment efficiently reduced P5CS1 expression levels and resulted in a decrease in drought tolerance in the ColFRI plants. The flc mutants with a functional FRI background also relieved FRI-mediated activation of P5CS1 during drought tolerance. Taken together, our findings reveal the novel function of FRI in enhancing drought resistance through its downstream P5CS1 pathway during water-deficit stress, which is dependent on its target, the FLC gene. Copyright © 2017 Elsevier Inc. All rights reserved.
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Zhang, Chen; Li, Xia; He, Yafei; Zhang, Jinfei; Yan, Ting; Liu, Xiaolong
2017-06-01
We compared the drought tolerance of wild-type (WT) and transgenic rice plants (PC) over-expressing the maize C 4 PEPC gene, which encodes phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) gene, and evaluated the roles of saccharide and sugar-related enzymes in the drought response. Pot-grown seedlings were subjected to real drought conditions outdoors, and the yield components were compared between PC and untransformed wild-type (WT) plants. The stable yield from PC plants was associated with higher net photosynthetic rate under the real drought treatment. The physiological characters of WT and PC seedlings under a simulated drought treatment (25% (w/v) polyethylene glycol-6000 for 3 h; PEG 6000 treatment) were analyzed in detail for the early response of drought. The relative water content was higher in PC than in WT, and PEPC activity and the C 4 -PEPC transcript level in PC were elevated under the simulated drought conditions. The endogenous saccharide responses also differed between PC and WT under simulated drought stress. The higher sugar decomposition rate in PC than in WT under drought analog stress was related to the increased activities of sucrose phosphate synthase, sucrose synthase, acid invertase, and neutral invertase, increased transcript levels of VIN1, CIN1, NIN1, SUT2, SUT4, and SUT5, and increased activities of superoxide dismutase and peroxidase in the leaves. The greater antioxidant defense capacity of PC and its relationship with saccharide metabolism was one of the reasons for the improved drought tolerance. In conclusion, PEPC effectively alleviated oxidative damage and enhanced the drought tolerance in rice plants, which were more related to the increase of the endogenous saccharide decomposition. These findings show that components of C 4 photosynthesis can be used to increase the yield of rice under drought conditions. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
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Sebastiana, Mónica; da Silva, Anabela Bernardes; Matos, Ana Rita; Alcântara, André; Silvestre, Susana; Malhó, Rui
2018-04-01
We investigated whether the performance of cork oak under drought could be improved by colonization with the ectomycorrhizal fungus Pisolithus tinctorius. Results show that inoculation alone had a positive effect on plant height, shoot biomass, shoot basal diameter, and root growth. Under drought, root growth of mycorrhizal plants was significantly increased showing that inoculation was effective in increasing tolerance to drought. In accordance, mycorrhizal plants subjected to drought showed less symptoms of stress when compared to non-mycorrhizal plants, such as lower concentration of soluble sugars and starch, increased ability to maintain fatty acid content and composition, and increased unsaturation level of membrane lipids. After testing some of the mechanisms suggested to contribute to the enhanced tolerance of mycorrhizal plants to drought, we could not find any by which Pisolithus tinctorius could benefit cork oak, at least under the drought conditions imposed in our experiment. Inoculation did not increase photosynthesis under drought, suggesting no effect in sustaining stomatal opening at low soil water content. Similarly, plant water status was not affected by inoculation suggesting that P. tinctorius does not contribute to an increased plant water uptake during drought. Inoculation did increase nitrogen concentration in plants but it was independent of the water status. Furthermore, no significant mycorrhizal effect on drought-induced ROS production or osmotic adjustment was detected, suggesting that these factors are not important for the improved drought tolerance triggered by P. tinctorius.
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Proteome Analysis of Date Palm (Phoenix dactylifera L.) under Severe Drought and Salt Stress.
El Rabey, Haddad A; Al-Malki, Abdulrahman L; Abulnaja, Khalid O
2016-01-01
Date palm cultivars differently tolerate salinity and drought stress. This study was carried out to study the response of date palm to severe salinity and drought based on leaf proteome analysis. Eighteen-month-old date palm plants were subjected to severe salt (48 g/L NaCl) and drought (82.5 g/L PEG or no irrigation) conditions for one month. Using a protein 2D electrophoresis method, 55 protein spots were analyzed using mass spectrometry. ATP synthase CF1 alpha chains were significantly upregulated under all three stress conditions. Changes in the abundance of RubisCO activase and one of the RubisCO fragments were significant in the same spots only for salt stress and drought stress with no irrigation, and oxygen-evolving enhancer protein 2 was changed in different spots. Transketolase was significantly changed only in drought stress with PEG. The expression of salt and drought stress genes of the chosen protein spots was either overexpressed or downexpressed as revealed by the high or low protein abundance, respectively. In addition, all drought tolerance genes due to no irrigation were downregulated. In conclusion, the proteome analysis of date palm under salinity and drought conditions indicated that both salinity and drought tolerance genes were differentially expressed resulting in high or low protein abundance of the chosen protein spots as a result of exposure to drought and salinity stress condition.
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UAV remote sensing for phenotyping drought tolerance in peanuts
NASA Astrophysics Data System (ADS)
Balota, Maria; Oakes, Joseph
2017-05-01
Farmers can benefit from growing drought tolerant peanut (Arachis hypogaea L.) cultivars with improved yield when rainfall is sporadic. In the Virginia-Carolina (VC) region, drought is magnified by hot summers and usually occurs in July and Aug when pod and seed growth are intense. At these growth stages, weekly supply of 50 to 75 mm of water is needed to ensure profitability. Irrigation can supplement crop water needs, but only 10% of the peanut farms are irrigated. In this frame, drought tolerant varieties can be profitable, but breeding for cultivars with improved drought tolerance requires fast yet accurate phenotyping. Our objective was to evaluate the potential of UAV remote sensing technologies for drought tolerance selection in peanut. In this study, we examined the effect of drought on leaf wilting, pod yield, grading characteristics, and crop value of 23 peanut cultivars (Virginia, Runner, and Valencia type). These varieties were arranged in a factorial design, with four replications drought stressed and two replications well-watered. Drought was imposed by covering the drought stressed plots with rainout shelters on July 19; they remained covered until August 29 and only received 38 mm irrigation in mid Aug. The well-watered plots continued to receive rain and supplemental irrigation as needed. During this time, Canopy Temperature Depression (CT) and Normalized Differential Vegetative Index (NDVI) were collected from the ground on all plots at weekly intervals. After the shelters were removed, these measurements were collected daily for approximately 2 weeks. At the same time, Red-Green-Blue (RGB), near-infrared (NIR), and infrared (IR) images taken from an UAV platform were also collected. Vegetation indices derived from the ground and aerial data were compared with leaf wilting, pod yield and crop value. Wilting, which is a common water stress symptom, was best estimated by NDVI and RGB, and least by CT; but CT was best in estimating yield, SMK and crop value in particular when taken on the ground at 15 days water stress imposition. Interestingly, CT predicted well plant wilting even before it occurred, i.e., correlation coefficients were negative and over 0.750 when CT was measured on July 19 and 20 even though wilting was visible only after two weeks. The data, yet preliminary, show promising potential for remote sensing technologies, at the ground and aerial, for peanut variety selection for improved drought tolerance.
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Benešová, Monika; Holá, Dana; Fischer, Lukáš; Jedelský, Petr L.; Hnilička, František; Wilhelmová, Naďa; Rothová, Olga; Kočová, Marie; Procházková, Dagmar; Honnerová, Jana; Fridrichová, Lenka; Hniličková, Helena
2012-01-01
Understanding the response of a crop to drought is the first step in the breeding of tolerant genotypes. In our study, two maize (Zea mays L.) genotypes with contrasting sensitivity to dehydration were subjected to moderate drought conditions. The subsequent analysis of their physiological parameters revealed a decreased stomatal conductance accompanied by a slighter decrease in the relative water content in the sensitive genotype. In contrast, the tolerant genotype maintained open stomata and active photosynthesis, even under dehydration conditions. Drought-induced changes in the leaf proteome were analyzed by two independent approaches, 2D gel electrophoresis and iTRAQ analysis, which provided compatible but only partially overlapping results. Drought caused the up-regulation of protective and stress-related proteins (mainly chaperones and dehydrins) in both genotypes. The differences in the levels of various detoxification proteins corresponded well with the observed changes in the activities of antioxidant enzymes. The number and levels of up-regulated protective proteins were generally lower in the sensitive genotype, implying a reduced level of proteosynthesis, which was also indicated by specific changes in the components of the translation machinery. Based on these results, we propose that the hypersensitive early stomatal closure in the sensitive genotype leads to the inhibition of photosynthesis and, subsequently, to a less efficient synthesis of the protective/detoxification proteins that are associated with drought tolerance. PMID:22719860
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Benešová, Monika; Holá, Dana; Fischer, Lukáš; Jedelský, Petr L; Hnilička, František; Wilhelmová, Naďa; Rothová, Olga; Kočová, Marie; Procházková, Dagmar; Honnerová, Jana; Fridrichová, Lenka; Hniličková, Helena
2012-01-01
Understanding the response of a crop to drought is the first step in the breeding of tolerant genotypes. In our study, two maize (Zea mays L.) genotypes with contrasting sensitivity to dehydration were subjected to moderate drought conditions. The subsequent analysis of their physiological parameters revealed a decreased stomatal conductance accompanied by a slighter decrease in the relative water content in the sensitive genotype. In contrast, the tolerant genotype maintained open stomata and active photosynthesis, even under dehydration conditions. Drought-induced changes in the leaf proteome were analyzed by two independent approaches, 2D gel electrophoresis and iTRAQ analysis, which provided compatible but only partially overlapping results. Drought caused the up-regulation of protective and stress-related proteins (mainly chaperones and dehydrins) in both genotypes. The differences in the levels of various detoxification proteins corresponded well with the observed changes in the activities of antioxidant enzymes. The number and levels of up-regulated protective proteins were generally lower in the sensitive genotype, implying a reduced level of proteosynthesis, which was also indicated by specific changes in the components of the translation machinery. Based on these results, we propose that the hypersensitive early stomatal closure in the sensitive genotype leads to the inhibition of photosynthesis and, subsequently, to a less efficient synthesis of the protective/detoxification proteins that are associated with drought tolerance.
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NASA Astrophysics Data System (ADS)
Semenov, Mikhail A.; Stratonovitch, Pierre; Paul, Matthew J.
2017-04-01
Short periods of extreme weather, such as a spell of high temperature or drought during a sensitive stage of development, could result in substantial yield losses due to reduction in grain number and grain size. In a modelling study (Stratonovitch & Semenov 2015), heat tolerance around flowering in wheat was identified as a key trait for increased yield potential in Europe under climate change. Ji et all (Ji et al. 2010) demonstrated cultivar specific responses of yield to drought stress around flowering in wheat. They hypothesised that carbohydrate supply to anthers may be the key in maintaining pollen fertility and grain number in wheat. It was shown in (Nuccio et al. 2015) that genetically modified varieties of maize that increase the concentration of sucrose in ear spikelets, performed better under non-drought and drought conditions in field experiments. The objective of this modelling study was to assess potential benefits of tolerance to drought during reproductive development for wheat yield potential and yield stability across Europe. We used the Sirius wheat model to optimise wheat ideotypes for 2050 (HadGEM2, RCP8.5) climate scenarios at selected European sites. Eight cultivar parameters were optimised to maximise mean yields, including parameters controlling phenology, canopy growth and water limitation. At those sites where water could be limited, ideotypes sensitive to drought produced substantially lower mean yields and higher yield variability compare with tolerant ideotypes. Therefore, tolerance to drought during reproductive development is likely to be required for wheat cultivars optimised for the future climate in Europe in order to achieve high yield potential and yield stability.
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Metabolite and transcript markers for the prediction of potato drought tolerance.
Sprenger, Heike; Erban, Alexander; Seddig, Sylvia; Rudack, Katharina; Thalhammer, Anja; Le, Mai Q; Walther, Dirk; Zuther, Ellen; Köhl, Karin I; Kopka, Joachim; Hincha, Dirk K
2018-04-01
Potato (Solanum tuberosum L.) is one of the most important food crops worldwide. Current potato varieties are highly susceptible to drought stress. In view of global climate change, selection of cultivars with improved drought tolerance and high yield potential is of paramount importance. Drought tolerance breeding of potato is currently based on direct selection according to yield and phenotypic traits and requires multiple trials under drought conditions. Marker-assisted selection (MAS) is cheaper, faster and reduces classification errors caused by noncontrolled environmental effects. We analysed 31 potato cultivars grown under optimal and reduced water supply in six independent field trials. Drought tolerance was determined as tuber starch yield. Leaf samples from young plants were screened for preselected transcript and nontargeted metabolite abundance using qRT-PCR and GC-MS profiling, respectively. Transcript marker candidates were selected from a published RNA-Seq data set. A Random Forest machine learning approach extracted metabolite and transcript markers for drought tolerance prediction with low error rates of 6% and 9%, respectively. Moreover, by combining transcript and metabolite markers, the prediction error was reduced to 4.3%. Feature selection from Random Forest models allowed model minimization, yielding a minimal combination of only 20 metabolite and transcript markers that were successfully tested for their reproducibility in 16 independent agronomic field trials. We demonstrate that a minimum combination of transcript and metabolite markers sampled at early cultivation stages predicts potato yield stability under drought largely independent of seasonal and regional agronomic conditions. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.
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Use of arbuscular mycorrhizal fungi to improve the drought tolerance of Cupressus atlantica G.
Zarik, Lamia; Meddich, Abdelilah; Hijri, Mohamed; Hafidi, Mohamed; Ouhammou, Ahmed; Ouahmane, Lahcen; Duponnois, Robin; Boumezzough, Ali
2016-01-01
In this study, we investigated whether indigenous arbuscular mycorrhizal (AM) fungi could improve the tolerance of Cupressus atlantica against water deficit. We tested a gradient of watering regime spanning from 90% to 25% of soil retention capacity of water on mycorhized and non-mycorhized seedlings in pot cultures with sterilized and non-sterilized soils. Our result showed a positive impact of AM fungi on shoot height, stem diameter and biomass as well as on the growth rate. We also observed that inoculation with AM fungi significantly improved uptake of minerals by C. atlantica in both sterilized and non-sterilized soils independently of water regimes. We found that mycorhized plants maintained higher relative water content (RWC) and water potential compared with non-mycorhized plants that were subjected to drought-stress regimes (50% and 25% of soil retention capacity). The contents of proline and of soluble sugars showed that their concentrations decreased in non-mycorhized plants subjected to DS. Superoxide dismutase (SOD) and catalase (CAT) activities also decreased in non-mycorhized plants submitted to DS compared to mycorhized plants. The same pattern was observed by measuring peroxidase (POD) enzyme activity. The results demonstrated that AM fungal inoculation promoted the growth and tolerance of C. atlantica against DS in pot cultures. Therefore, mycorrhizal inoculation could be a potential solution for the conservation and reestablishment of C. atlantica in its natural ecosystem. Copyright © 2016 Académie des sciences. Published by Elsevier SAS. All rights reserved.
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Mofatto, Luciana Souto; Carneiro, Fernanda de Araújo; Vieira, Natalia Gomes; Duarte, Karoline Estefani; Vidal, Ramon Oliveira; Alekcevetch, Jean Carlos; Cotta, Michelle Guitton; Verdeil, Jean-Luc; Lapeyre-Montes, Fabienne; Lartaud, Marc; Leroy, Thierry; De Bellis, Fabien; Pot, David; Rodrigues, Gustavo Costa; Carazzolle, Marcelo Falsarella; Pereira, Gonçalo Amarante Guimarães; Andrade, Alan Carvalho; Marraccini, Pierre
2016-04-19
Drought is a widespread limiting factor in coffee plants. It affects plant development, fruit production, bean development and consequently beverage quality. Genetic diversity for drought tolerance exists within the coffee genus. However, the molecular mechanisms underlying the adaptation of coffee plants to drought are largely unknown. In this study, we compared the molecular responses to drought in two commercial cultivars (IAPAR59, drought-tolerant and Rubi, drought-susceptible) of Coffea arabica grown in the field under control (irrigation) and drought conditions using the pyrosequencing of RNA extracted from shoot apices and analysing the expression of 38 candidate genes. Pyrosequencing from shoot apices generated a total of 34.7 Mbp and 535,544 reads enabling the identification of 43,087 clusters (41,512 contigs and 1,575 singletons). These data included 17,719 clusters (16,238 contigs and 1,575 singletons) exclusively from 454 sequencing reads, along with 25,368 hybrid clusters assembled with 454 sequences. The comparison of DNA libraries identified new candidate genes (n = 20) presenting differential expression between IAPAR59 and Rubi and/or drought conditions. Their expression was monitored in plagiotropic buds, together with those of other (n = 18) candidates genes. Under drought conditions, up-regulated expression was observed in IAPAR59 but not in Rubi for CaSTK1 (protein kinase), CaSAMT1 (SAM-dependent methyltransferase), CaSLP1 (plant development) and CaMAS1 (ABA biosynthesis). Interestingly, the expression of lipid-transfer protein (nsLTP) genes was also highly up-regulated under drought conditions in IAPAR59. This may have been related to the thicker cuticle observed on the abaxial leaf surface in IAPAR59 compared to Rubi. The full transcriptome assembly of C. arabica, followed by functional annotation, enabled us to identify differentially expressed genes related to drought conditions. Using these data, candidate genes were selected and their differential expression profiles were confirmed by qPCR experiments in plagiotropic buds of IAPAR59 and Rubi under drought conditions. As regards the genes up-regulated under drought conditions, specifically in the drought-tolerant IAPAR59, several corresponded to orphan genes but also to genes coding proteins involved in signal transduction pathways, as well as ABA and lipid metabolism, for example. The identification of these genes should help advance our understanding of the genetic determinism of drought tolerance in coffee.
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Phenotyping common beans for adaptation to drought
Beebe, Stephen E.; Rao, Idupulapati M.; Blair, Matthew W.; Acosta-Gallegos, Jorge A.
2013-01-01
Common beans (Phaseolus vulgaris L.) originated in the New World and are the grain legume of greatest production for direct human consumption. Common bean production is subject to frequent droughts in highland Mexico, in the Pacific coast of Central America, in northeast Brazil, and in eastern and southern Africa from Ethiopia to South Africa. This article reviews efforts to improve common bean for drought tolerance, referring to genetic diversity for drought response, the physiology of drought tolerance mechanisms, and breeding strategies. Different races of common bean respond differently to drought, with race Durango of highland Mexico being a major source of genes. Sister species of P. vulgaris likewise have unique traits, especially P. acutifolius which is well adapted to dryland conditions. Diverse sources of tolerance may have different mechanisms of plant response, implying the need for different methods of phenotyping to recognize the relevant traits. Practical considerations of field management are discussed including: trial planning; water management; and field preparation. PMID:23507928
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Zhang, Tiejun; Yu, Long-Xi; Zheng, Ping; Li, Yajun; Rivera, Martha; Main, Dorrie; Greene, Stephanie L
2015-01-01
Drought resistance is an important breeding target for enhancing alfalfa productivity in arid and semi-arid regions. Identification of genes involved in drought tolerance will facilitate breeding for improving drought resistance and water use efficiency in alfalfa. Our objective was to use a diversity panel of alfalfa accessions comprised of 198 cultivars and landraces to identify genes involved in drought tolerance. The panel was selected from the USDA-ARS National Plant Germplasm System alfalfa collection and genotyped using genotyping by sequencing. A greenhouse procedure was used for phenotyping two important traits associated with drought tolerance: drought resistance index (DRI) and relative leaf water content (RWC). Marker-trait association identified nineteen and fifteen loci associated with DRI and RWC, respectively. Alignments of target sequences flanking to the resistance loci against the reference genome of M. truncatula revealed multiple chromosomal locations. Markers associated with DRI are located on all chromosomes while markers associated with RWC are located on chromosomes 1, 2, 3, 4, 5, 6 and 7. Co-localizations of significant markers between DRI and RWC were found on chromosomes 3, 5 and 7. Most loci associated with DRI in this work overlap with the reported QTLs associated with biomass under drought in alfalfa. Additional significant markers were targeted to several contigs with unknown chromosomal locations. BLAST search using their flanking sequences revealed homology to several annotated genes with functions in stress tolerance. With further validation, these markers may be used for marker-assisted breeding new alfalfa varieties with drought resistance and enhanced water use efficiency.
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Szalonek, Michal; Sierpien, Barbara; Rymaszewski, Wojciech; Gieczewska, Katarzyna; Garstka, Maciej; Lichocka, Malgorzata; Sass, Laszlo; Paul, Kenny; Vass, Imre; Vankova, Radomira; Dobrev, Peter; Szczesny, Pawel; Marczewski, Waldemar; Krusiewicz, Dominika; Strzelczyk-Zyta, Danuta; Hennig, Jacek; Konopka-Postupolska, Dorota
2015-01-01
Annexins are a family of calcium- and membrane-binding proteins that are important for plant tolerance to adverse environmental conditions. Annexins function to counteract oxidative stress, maintain cell redox homeostasis, and enhance drought tolerance. In the present study, an endogenous annexin, STANN1, was overexpressed to determine whether crop yields could be improved in potato (Solanum tuberosum L.) during drought. Nine potential potato annexins were identified and their expression characterized in response to drought treatment. STANN1 mRNA was constitutively expressed at a high level and drought treatment strongly increased transcription levels. Therefore, STANN1 was selected for overexpression analysis. Under drought conditions, transgenic potato plants ectopically expressing STANN1 were more tolerant to water deficit in the root zone, preserved more water in green tissues, maintained chloroplast functions, and had higher accumulation of chlorophyll b and xanthophylls (especially zeaxanthin) than wild type (WT). Drought-induced reductions in the maximum efficiency and the electron transport rate of photosystem II (PSII), as well as the quantum yield of photosynthesis, were less pronounced in transgenic plants overexpressing STANN1 than in the WT. This conferred more efficient non-photochemical energy dissipation in the outer antennae of PSII and probably more efficient protection of reaction centers against photooxidative damage in transgenic plants under drought conditions. Consequently, these plants were able to maintain effective photosynthesis during drought, which resulted in greater productivity than WT plants despite water scarcity. Although the mechanisms underlying this stress protection are not yet clear, annexin-mediated photoprotection is probably linked to protection against light-induced oxidative stress.
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Szalonek, Michal; Sierpien, Barbara; Rymaszewski, Wojciech; Gieczewska, Katarzyna; Garstka, Maciej; Lichocka, Malgorzata; Sass, Laszlo; Paul, Kenny; Vass, Imre; Vankova, Radomira; Dobrev, Peter; Szczesny, Pawel; Marczewski, Waldemar; Krusiewicz, Dominika; Strzelczyk-Zyta, Danuta; Hennig, Jacek; Konopka-Postupolska, Dorota
2015-01-01
Annexins are a family of calcium- and membrane-binding proteins that are important for plant tolerance to adverse environmental conditions. Annexins function to counteract oxidative stress, maintain cell redox homeostasis, and enhance drought tolerance. In the present study, an endogenous annexin, STANN1, was overexpressed to determine whether crop yields could be improved in potato (Solanum tuberosum L.) during drought. Nine potential potato annexins were identified and their expression characterized in response to drought treatment. STANN1 mRNA was constitutively expressed at a high level and drought treatment strongly increased transcription levels. Therefore, STANN1 was selected for overexpression analysis. Under drought conditions, transgenic potato plants ectopically expressing STANN1 were more tolerant to water deficit in the root zone, preserved more water in green tissues, maintained chloroplast functions, and had higher accumulation of chlorophyll b and xanthophylls (especially zeaxanthin) than wild type (WT). Drought-induced reductions in the maximum efficiency and the electron transport rate of photosystem II (PSII), as well as the quantum yield of photosynthesis, were less pronounced in transgenic plants overexpressing STANN1 than in the WT. This conferred more efficient non-photochemical energy dissipation in the outer antennae of PSII and probably more efficient protection of reaction centers against photooxidative damage in transgenic plants under drought conditions. Consequently, these plants were able to maintain effective photosynthesis during drought, which resulted in greater productivity than WT plants despite water scarcity. Although the mechanisms underlying this stress protection are not yet clear, annexin-mediated photoprotection is probably linked to protection against light-induced oxidative stress. PMID:26172952
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Nguyen, Kien Huu; Ha, Chien Van; Nishiyama, Rie; Watanabe, Yasuko; Leyva-González, Marco Antonio; Fujita, Yasunari; Tran, Uven Thi; Li, Weiqiang; Tanaka, Maho; Seki, Motoaki; Schaller, G. Eric; Herrera-Estrella, Luis; Tran, Lam-Son Phan
2016-01-01
In this study, we used a loss-of-function approach to elucidate the functions of three Arabidopsis type B response regulators (ARRs)—namely ARR1, ARR10, and ARR12—in regulating the Arabidopsis plant responses to drought. The arr1,10,12 triple mutant showed a significant increase in drought tolerance versus WT plants, as indicated by its higher relative water content and survival rate on drying soil. This enhanced drought tolerance of arr1,10,12 plants can be attributed to enhanced cell membrane integrity, increased anthocyanin biosynthesis, abscisic acid (ABA) hypersensitivity, and reduced stomatal aperture, but not to altered stomatal density. Further drought-tolerance tests of lower-order double and single mutants indicated that ARR1, ARR10, and ARR12 negatively and redundantly control plant responses to drought, with ARR1 appearing to bear the most critical function among the three proteins. In agreement with these findings, a comparative genome-wide analysis of the leaves of arr1,10,12 and WT plants under both normal and dehydration conditions suggested a cytokinin (CK) signaling-mediated network controlling plant adaptation to drought via many dehydration/drought- and/or ABA-responsive genes that can provide osmotic adjustment and protection to cellular and membrane structures. Expression of all three ARR genes was repressed by dehydration and ABA treatments, inferring that plants down-regulate these genes as an adaptive mechanism to survive drought. Collectively, our results demonstrate that repression of CK response, and thus CK signaling, is one of the strategies plants use to cope with water deficit, providing novel insight for the design of drought-tolerant plants by genetic engineering. PMID:26884175
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Nguyen, Kien Huu; Ha, Chien Van; Nishiyama, Rie; Watanabe, Yasuko; Leyva-González, Marco Antonio; Fujita, Yasunari; Tran, Uven Thi; Li, Weiqiang; Tanaka, Maho; Seki, Motoaki; Schaller, G Eric; Herrera-Estrella, Luis; Tran, L S
2016-03-15
In this study, we used a loss-of-function approach to elucidate the functions of three Arabidopsis type B response regulators (ARRs)--namely ARR1, ARR10, and ARR12--in regulating the Arabidopsis plant responses to drought. The arr1,10,12 triple mutant showed a significant increase in drought tolerance versus WT plants, as indicated by its higher relative water content and survival rate on drying soil. This enhanced drought tolerance of arr1,10,12 plants can be attributed to enhanced cell membrane integrity, increased anthocyanin biosynthesis, abscisic acid (ABA) hypersensitivity, and reduced stomatal aperture, but not to altered stomatal density. Further drought-tolerance tests of lower-order double and single mutants indicated that ARR1, ARR10, and ARR12 negatively and redundantly control plant responses to drought, with ARR1 appearing to bear the most critical function among the three proteins. In agreement with these findings, a comparative genome-wide analysis of the leaves of arr1,10,12 and WT plants under both normal and dehydration conditions suggested a cytokinin (CK) signaling-mediated network controlling plant adaptation to drought via many dehydration/drought- and/or ABA-responsive genes that can provide osmotic adjustment and protection to cellular and membrane structures. Expression of all three ARR genes was repressed by dehydration and ABA treatments, inferring that plants down-regulate these genes as an adaptive mechanism to survive drought. Collectively, our results demonstrate that repression of CK response, and thus CK signaling, is one of the strategies plants use to cope with water deficit, providing novel insight for the design of drought-tolerant plants by genetic engineering.
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Phenotypic approaches to drought in cassava: review
Okogbenin, Emmanuel; Setter, Tim L.; Ferguson, Morag; Mutegi, Rose; Ceballos, Hernan; Olasanmi, Bunmi; Fregene, Martin
2012-01-01
Cassava is an important crop in Africa, Asia, Latin America, and the Caribbean. Cassava can be produced adequately in drought conditions making it the ideal food security crop in marginal environments. Although cassava can tolerate drought stress, it can be genetically improved to enhance productivity in such environments. Drought adaptation studies in over three decades in cassava have identified relevant mechanisms which have been explored in conventional breeding. Drought is a quantitative trait and its multigenic nature makes it very challenging to effectively manipulate and combine genes in breeding for rapid genetic gain and selection process. Cassava has a long growth cycle of 12–18 months which invariably contributes to a long breeding scheme for the crop. Modern breeding using advances in genomics and improved genotyping, is facilitating the dissection and genetic analysis of complex traits including drought tolerance, thus helping to better elucidate and understand the genetic basis of such traits. A beneficial goal of new innovative breeding strategies is to shorten the breeding cycle using minimized, efficient or fast phenotyping protocols. While high throughput genotyping have been achieved, this is rarely the case for phenotyping for drought adaptation. Some of the storage root phenotyping in cassava are often done very late in the evaluation cycle making selection process very slow. This paper highlights some modified traits suitable for early-growth phase phenotyping that may be used to reduce drought phenotyping cycle in cassava. Such modified traits can significantly complement the high throughput genotyping procedures to fast track breeding of improved drought tolerant varieties. The need for metabolite profiling, improved phenomics to take advantage of next generation sequencing technologies and high throughput phenotyping are basic steps for future direction to improve genetic gain and maximize speed for drought tolerance breeding. PMID:23717282
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A Proteomics Approach to Discover Drought Tolerance Proteins in Wheat Pollen Grain at Meiosis Stage.
Fotovat, Reza; Alikhani, Mehdi; Valizadeh, Mostafa; Mirzaei, Mehdi; Salekdeh, Ghasem H
2017-01-01
Plants reproductive phase, when grain yield and consequently farmers' investment is most in jeopardy, is considered as the most sensitive stage to drought stress. In this study, we aimed to explore the proteomic response of wheat anther at meiosis stage in a drought tolerant, Darab, and susceptible, Shiraz, wheat genotypes. Wheat plants were exposed to drought stress at meiosis stage for four days under controlled environmental conditions. Then, anthers from both genotypes were sampled, and their proteomes were examined via quantitative proteomics analysis. Our results demonstrated that short-term stress at meiosis stage reduced plant seed-setting compared to well-watered plants. This reduction was more pronounced in the susceptible genotype, Shiraz, by 51%, compared to the drought tolerant Darab by 14.3%. Proteome analysis revealed that 60 protein spots were drought responsive, out of which 44 were identified using a mass spectrometer. We observed a dramatic up-regulation of several heat shock proteins, as well as induction of Bet v I allergen family proteins, peroxiredoxin-5, and glutathione transferase with similar abundance in both genotypes. However, the abundance of proteins such as several stress response related proteins, including glutaredoxin, proteasome subunit alpha type 5, and ribosomal proteins showed a different response to drought stress in two genotypes. The differential abundance of proteins in two genotypes may suggest mechanisms by which tolerant genotype cope with drought stress. To the best of our knowledge, this is the first proteome analysis of plant reproductive tissue response to drought stress in wheat and could broaden our insight into plant adaptation to drought stress. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.
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Nakashima, Kazuo; Yamaguchi-Shinozaki, Kazuko; Shinozaki, Kazuo
2014-01-01
Drought negatively impacts plant growth and the productivity of crops around the world. Understanding the molecular mechanisms in the drought response is important for improvement of drought tolerance using molecular techniques. In plants, abscisic acid (ABA) is accumulated under osmotic stress conditions caused by drought, and has a key role in stress responses and tolerance. Comprehensive molecular analyses have shown that ABA regulates the expression of many genes under osmotic stress conditions, and the ABA-responsive element (ABRE) is the major cis-element for ABA-responsive gene expression. Transcription factors (TFs) are master regulators of gene expression. ABRE-binding protein and ABRE-binding factor TFs control gene expression in an ABA-dependent manner. SNF1-related protein kinases 2, group A 2C-type protein phosphatases, and ABA receptors were shown to control the ABA signaling pathway. ABA-independent signaling pathways such as dehydration-responsive element-binding protein TFs and NAC TFs are also involved in stress responses including drought, heat, and cold. Recent studies have suggested that there are interactions between the major ABA signaling pathway and other signaling factors in stress responses. The important roles of these TFs in crosstalk among abiotic stress responses will be discussed. Control of ABA or stress signaling factor expression can improve tolerance to environmental stresses. Recent studies using crops have shown that stress-specific overexpression of TFs improves drought tolerance and grain yield compared with controls in the field.
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Janiak, Agnieszka; Kwasniewski, Miroslaw; Sowa, Marta; Gajek, Katarzyna; Żmuda, Katarzyna; Kościelniak, Janusz; Szarejko, Iwona
2018-01-01
Plant survival in adverse environmental conditions requires a substantial change in the metabolism, which is reflected by the extensive transcriptome rebuilding upon the occurrence of the stress. Therefore, transcriptomic studies offer an insight into the mechanisms of plant stress responses. Here, we present the results of global gene expression profiling of roots and leaves of two barley genotypes with contrasting ability to cope with drought stress. Our analysis suggests that drought tolerance results from a certain level of transcription of stress-influenced genes that is present even before the onset of drought. Genes that predispose the plant to better drought survival play a role in the regulatory network of gene expression, including several transcription factors, translation regulators and structural components of ribosomes. An important group of genes is involved in signaling mechanisms, with significant contribution of hormone signaling pathways and an interplay between ABA, auxin, ethylene and brassinosteroid homeostasis. Signal transduction in a drought tolerant genotype may be more efficient through the expression of genes required for environmental sensing that are active already during normal water availability and are related to actin filaments and LIM domain proteins, which may function as osmotic biosensors. Better survival of drought may also be attributed to more effective processes of energy generation and more efficient chloroplasts biogenesis. Interestingly, our data suggest that several genes involved in a photosynthesis process are required for the establishment of effective drought response not only in leaves, but also in roots of barley. Thus, we propose a hypothesis that root plastids may turn into the anti-oxidative centers protecting root macromolecules from oxidative damage during drought stress. Specific genes and their potential role in building up a drought-tolerant barley phenotype is extensively discussed with special emphasis on processes that take place in barley roots. When possible, the interconnections between particular factors are emphasized to draw a broader picture of the molecular mechanisms of drought tolerance in barley. PMID:29375595
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Janiak, Agnieszka; Kwasniewski, Miroslaw; Sowa, Marta; Gajek, Katarzyna; Żmuda, Katarzyna; Kościelniak, Janusz; Szarejko, Iwona
2017-01-01
Plant survival in adverse environmental conditions requires a substantial change in the metabolism, which is reflected by the extensive transcriptome rebuilding upon the occurrence of the stress. Therefore, transcriptomic studies offer an insight into the mechanisms of plant stress responses. Here, we present the results of global gene expression profiling of roots and leaves of two barley genotypes with contrasting ability to cope with drought stress. Our analysis suggests that drought tolerance results from a certain level of transcription of stress-influenced genes that is present even before the onset of drought. Genes that predispose the plant to better drought survival play a role in the regulatory network of gene expression, including several transcription factors, translation regulators and structural components of ribosomes. An important group of genes is involved in signaling mechanisms, with significant contribution of hormone signaling pathways and an interplay between ABA, auxin, ethylene and brassinosteroid homeostasis. Signal transduction in a drought tolerant genotype may be more efficient through the expression of genes required for environmental sensing that are active already during normal water availability and are related to actin filaments and LIM domain proteins, which may function as osmotic biosensors. Better survival of drought may also be attributed to more effective processes of energy generation and more efficient chloroplasts biogenesis. Interestingly, our data suggest that several genes involved in a photosynthesis process are required for the establishment of effective drought response not only in leaves, but also in roots of barley. Thus, we propose a hypothesis that root plastids may turn into the anti-oxidative centers protecting root macromolecules from oxidative damage during drought stress. Specific genes and their potential role in building up a drought-tolerant barley phenotype is extensively discussed with special emphasis on processes that take place in barley roots. When possible, the interconnections between particular factors are emphasized to draw a broader picture of the molecular mechanisms of drought tolerance in barley.
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Coping with drought: stress and adaptive responses in potato and perspectives for improvement
Obidiegwu, Jude E.; Bryan, Glenn J.; Jones, Hamlyn G.; Prashar, Ankush
2015-01-01
Potato (Solanum tuberosum L.) is often considered as a drought sensitive crop and its sustainable production is threatened due to frequent drought episodes. There has been much research aiming to understand the physiological, biochemical, and genetic basis of drought tolerance in potato as a basis for improving production under drought conditions. The complex phenotypic response of potato plants to drought is conditioned by the interactive effects of the plant's genotypic potential, developmental stage, and environment. Effective crop improvement for drought tolerance will require the pyramiding of many disparate characters, with different combinations being appropriate for different growing environments. An understanding of the interaction between below ground water uptake by the roots and above ground water loss from the shoot system is essential. The development of high throughput precision phenotyping platforms is providing an exciting new tool for precision screening, which, with the incorporation of innovative screening strategies, can aid the selection and pyramiding of drought-related genes appropriate for specific environments. Outcomes from genomics, proteomics, metabolomics, and bioengineering advances will undoubtedly compliment conventional breeding strategies and presents an alternative route toward development of drought tolerant potatoes. This review presents an overview of past research activity, highlighting recent advances with examples from other crops and suggesting future research directions. PMID:26257752
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Fracasso, Alessandra; Magnanini, Eugenio; Marocco, Adriano; Amaducci, Stefano
2017-01-01
Plant growth and productivity are strongly affected by limited water availability in drought prone environments. The current climate change scenario, characterized by long periods without precipitations followed by short but intense rainfall, forces plants to implement different strategies to cope with drought stress. Understanding how plants use water during periods of limited water availability is of primary importance to identify and select the best adapted genotypes to a certain environment. Two sorghum genotypes IS22330 and IS20351, previously characterized as drought tolerant and drought sensitive genotypes, were subjected to progressive drought stress through a dry-down experiment. A whole-canopy multi-chamber system was used to determine the in vivo water use efficiency (WUE). This system records whole-canopy net photosynthetic and transpiration rate of 12 chambers five times per hour allowing the calculation of whole-canopy instantaneous WUE daily trends. Daily net photosynthesis and transpiration rates were coupled with gene expression dynamics of five drought related genes. Under drought stress, the tolerant genotype increased expression level for all the genes analyzed, whilst the opposite trend was highlighted by the drought sensitive genotype. Correlation between gene expression dynamics and gas exchange measurements allowed to identify three genes as valuable candidate to assess drought tolerance in sorghum.
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Fracasso, Alessandra; Magnanini, Eugenio; Marocco, Adriano; Amaducci, Stefano
2017-01-01
Plant growth and productivity are strongly affected by limited water availability in drought prone environments. The current climate change scenario, characterized by long periods without precipitations followed by short but intense rainfall, forces plants to implement different strategies to cope with drought stress. Understanding how plants use water during periods of limited water availability is of primary importance to identify and select the best adapted genotypes to a certain environment. Two sorghum genotypes IS22330 and IS20351, previously characterized as drought tolerant and drought sensitive genotypes, were subjected to progressive drought stress through a dry-down experiment. A whole-canopy multi-chamber system was used to determine the in vivo water use efficiency (WUE). This system records whole-canopy net photosynthetic and transpiration rate of 12 chambers five times per hour allowing the calculation of whole-canopy instantaneous WUE daily trends. Daily net photosynthesis and transpiration rates were coupled with gene expression dynamics of five drought related genes. Under drought stress, the tolerant genotype increased expression level for all the genes analyzed, whilst the opposite trend was highlighted by the drought sensitive genotype. Correlation between gene expression dynamics and gas exchange measurements allowed to identify three genes as valuable candidate to assess drought tolerance in sorghum. PMID:28620409
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Marraccini, Pierre; Vinecky, Felipe; Alves, Gabriel S.C.; Ramos, Humberto J.O.; Elbelt, Sonia; Vieira, Natalia G.; Carneiro, Fernanda A.; Sujii, Patricia S.; Alekcevetch, Jean C.; Silva, Vânia A.; DaMatta, Fábio M.; Ferrão, Maria A.G.; Leroy, Thierry; Pot, David; Vieira, Luiz G.E.; da Silva, Felipe R.; Andrade, Alan C.
2012-01-01
The aim of this study was to investigate the molecular mechanisms underlying drought acclimation in coffee plants by the identification of candidate genes (CGs) using different approaches. The first approach used the data generated during the Brazilian Coffee expressed sequence tag (EST) project to select 13 CGs by an in silico analysis (electronic northern). The second approach was based on screening macroarrays spotted with plasmid DNA (coffee ESTs) with separate hybridizations using leaf cDNA probes from drought-tolerant and susceptible clones of Coffea canephora var. Conilon, grown under different water regimes. This allowed the isolation of seven additional CGs. The third approach used two-dimensional gel electrophoresis to identify proteins displaying differential accumulation in leaves of drought-tolerant and susceptible clones of C. canephora. Six of them were characterized by MALDI-TOF-MS/MS (matrix-assisted laser desorption-time of flight-tandem mass spectrometry) and the corresponding proteins were identified. Finally, additional CGs were selected from the literature, and quantitative real-time polymerase chain reaction (qPCR) was performed to analyse the expression of all identified CGs. Altogether, >40 genes presenting differential gene expression during drought acclimation were identified, some of them showing different expression profiles between drought-tolerant and susceptible clones. Based on the obtained results, it can be concluded that factors involved a complex network of responses probably involving the abscisic signalling pathway and nitric oxide are major molecular determinants that might explain the better efficiency in controlling stomata closure and transpiration displayed by drought-tolerant clones of C. canephora. PMID:22511801
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Metabolic Effects of Acibenzolar-S-Methyl for Improving Heat or Drought Stress in Creeping Bentgrass
Jespersen, David; Yu, Jingjin; Huang, Bingru
2017-01-01
Acibenzolar-S-methyl (ASM) is a synthetic functional analog of salicylic acid which can induce systemic acquired resistance in plants, but its effects on abiotic stress tolerance is not well known. The objectives of this study were to examine effects of acibenzolar-S-methyl on heat or drought tolerance in creeping bentgrass (Agrostis stolonifera) and to determine major ASM-responsive metabolites and proteins associated with enhanced abiotic stress tolerance. Creeping bentgrass plants (cv. ‘Penncross’) were foliarly sprayed with ASM and were exposed to non-stress (20/15°C day/night), heat stress (35/30°C), or drought conditions (by withholding irrigation) in controlled-environment growth chambers. Exogenous ASM treatment resulted in improved heat or drought tolerance, as demonstrated by higher overall turf quality, relative water content, and chlorophyll content compared to the untreated control. Western blotting revealed that ASM application resulted in up-regulation of ATP synthase, HSP-20, PR-3, and Rubisco in plants exposed to heat stress, and greater accumulation of dehydrin in plants exposed to drought stress. Metabolite profiling identified a number of amino acids, organic acids, and sugars which were differentially accumulated between ASM treated and untreated plants under heat or drought stress, including aspartic acid, glycine, citric acid, malic acid, and the sugars glucose, and fructose. Our results suggested that ASM was effective in improving heat or drought tolerance in creeping bentgrass, mainly through enhancing protein synthesis and metabolite accumulation involved in osmotic adjustment, energy metabolism, and stress signaling. PMID:28744300
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Wang, Lin; Li, Qing-Tian; Lei, Qiong; Feng, Chao; Zheng, Xiaodong; Zhou, Fangfang; Li, Lingzi; Liu, Xuan; Wang, Zhi; Kong, Jin
2017-12-19
Water deficit severely reduces apple growth and production, is detrimental to fruit quality and size. This problem is exacerbated as global warming is implicated in producing more severe drought stress. Thus water-efficiency has becomes the major target for apple breeding. A desired apple tree can absorb and transport water efficiently, which not only confers improved drought tolerance, but also guarantees fruit size for higher income returns. Aquaporins, as water channels, control water transportation across membranes and can regulate water flow by changing their amount and activity. The exploration of molecular mechanism of water efficiency and the gene wealth will pave a way for molecular breeding of drought tolerant apple tree. In the current study, we screened out a drought inducible aquaporin gene MdPIP1;3, which specifically enhanced its expression during fruit expansion in 'Fuji' apple (Malus domestica Borkh. cv. Red Fuji). It localized on plasma membranes and belonged to PIP1 subfamily. The tolerance to drought stress enhanced in transgenic tomato plants ectopically expressing MdPIP1;3, showing that the rate of losing water in isolated transgenic leaves was slower than wild type, and stomata of transgenic plants closed sensitively to respond to drought compared with wild type. Besides, length and diameter of transgenic tomato fruits increased faster than wild type, and in final, fruit sizes and fresh weights of transgenic tomatoes were bigger than wild type. Specially, in cell levels, fruit cell size from transgenic tomatoes was larger than wild type, showing that cell number per mm 2 in transgenic fruits was less than wild type. Altogether, ectopically expressing MdPIP1;3 enhanced drought tolerance of transgenic tomatoes partially via reduced water loss controlled by stomata closure in leaves. In addition, the transgenic tomato fruits are larger and heavier with larger cells via more efficient water transportation across membranes. Our research will contribute to apple production, by engineering apples with big fruits via efficient water transportation when well watered and enhanced drought tolerance in transgenic apples under water deficit.
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Raineri, Jesica; Ribichich, Karina F; Chan, Raquel L
2015-12-01
Arabidopsis transgenic plants expressing the sunflower transcription factor HaWRKY76 exhibit increased yield and tolerance to drought and flood stresses. The genetic construct containing HaWRKY76 is proposed as a potential biotechnological tool to improve crops. Water deficit and water excess are abiotic stress factors that seriously affect crops worldwide. To increase the tolerance to such stresses without causing yield penalty constitutes a major goal for biotechnologists. In this survey, we report that HaWRKY76, a divergent sunflower WRKY transcription factor, is able to confer both dehydration and submergence tolerance to Arabidopsis transgenic plants without yield penalty. The expression pattern of HaWRKY76 was analyzed in plants grown in standard conditions and under different watering regimes indicating a regulation by water availability. The corresponding cDNA was isolated and cloned under the control of a constitutive promoter and Arabidopsis plants were transformed with this construct. These transgenic plants presented higher biomass, seed production and sucrose content than controls in standard growth conditions. Moreover, they exhibited tolerance to mild drought or flood (complete submergence/waterlogging) stresses as well as the same or increased yield, depending on the stress severity and plant developmental stage, compared with controls. Drought tolerance occurred via an ABA-independent mechanism and induction of stomatal closure. Submergence tolerance can be explained by the carbohydrate (sucrose and starch) preservation achieved through the repression of fermentation pathways. Higher cell membrane stability and chlorenchyma maintenance could be the nexus between tolerance responses in front of both stresses. Altogether, the obtained results indicated that HaWRKY76 can be a potential biotechnological tool to improve crops yield as well as drought and flood tolerances.
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Liu, Changyou; Wu, Jing; Wang, Lanfen; Fan, Baojie; Cao, Zhimin; Su, Qiuzhu; Zhang, Zhixiao; Wang, Yan; Tian, Jing; Wang, Shumin
2017-11-01
A novel genetic linkage map was constructed using SSR markers and stable QTLs were identified for six drought tolerance related-traits using single-environment analysis under irrigation and drought treatments. Mungbean (Vigna radiata L.) is one of the most important leguminous food crops. However, mungbean production is seriously constrained by drought. Isolation of drought-responsive genetic elements and marker-assisted selection breeding will benefit from the detection of quantitative trait locus (QTLs) for traits related to drought tolerance. In this study, we developed a full-coverage genetic linkage map based on simple sequence repeat (SSR) markers using a recombinant inbred line (RIL) population derived from an intra-specific cross between two drought-resistant varieties. This novel map was anchored with 313 markers. The total map length was 1010.18 cM across 11 linkage groups, covering the entire genome of mungbean with a saturation of one marker every 3.23 cM. We subsequently detected 58 QTLs for plant height (PH), maximum leaf area (MLA), biomass (BM), relative water content, days to first flowering, and seed yield (Yield) and 5 for the drought tolerance index of 3 traits in irrigated and drought environments at 2 locations. Thirty-eight of these QTLs were consistently detected two or more times at similar linkage positions. Notably, qPH5A and qMLA2A were consistently identified in marker intervals from GMES5773 to MUS128 in LG05 and from Mchr11-34 to the HAAS_VR_1812 region in LG02 in four environments, contributing 6.40-20.06% and 6.97-7.94% of the observed phenotypic variation, respectively. None of these QTLs shared loci with previously identified drought-related loci from mungbean. The results of these analyses might facilitate the isolation of drought-related genes and help to clarify the mechanism of drought tolerance in mungbean.
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Abbaspour, H; Saeidi-Sar, S; Afshari, H; Abdel-Wahhab, M A
2012-05-01
The influence of Glomus etunicatum colonization on plant growth and drought tolerance of 3-month-old Pistacia vera seedlings in potted culture was studied in two different water treatments. The arbuscular mycorrhiza (AM) inoculation and plant growth (including plant shoot and root weight, leaf area, and total chlorophyll) were higher for well-watered than for water-stressed plants. The growth of AM-treated seedlings was higher than non-AM-treatment regardless of water status. P, K, Zn and Cu contents in AM-treated shoots were greater than those in non-AM shoots under well-watered conditions and drought stress. N and Ca content were higher under drought stress, while AM symbiosis did not affect the Mg content. The contents of soluble sugars, proteins, flavonoid and proline were higher in mycorrhizal than non-mycorrhizal-treated plants under the whole water regime. AM colonization increased the activities of peroxidase enzyme in treatments, but did not affect the catalase activity in shoots and roots under well-watered conditions and drought stress. We conclude that AM colonization improved the drought tolerance of P. vera seedlings by increasing the accumulation of osmotic adjustment compounds, nutritional and antioxidant enzyme activity. It appears that AM formation enhanced the drought tolerance of pistachio plants, which increased host biomass and plant growth. Copyright © 2012 Elsevier GmbH. All rights reserved.
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Quantitative Proteomic Analysis of Wheat Cultivars with Differing Drought Stress Tolerance
Ford, Kristina L.; Cassin, Andrew; Bacic, Antony
2011-01-01
Using a series of multiplexed experiments we studied the quantitative changes in protein abundance of three Australian bread wheat cultivars (Triticum aestivum L.) in response to a drought stress. Three cultivars differing in their ability to maintain grain yield during drought, Kukri (intolerant), Excalibur (tolerant), and RAC875 (tolerant), were grown in the glasshouse with cyclic drought treatment that mimicked conditions in the field. Proteins were isolated from leaves of mature plants and isobaric tags were used to follow changes in the relative protein abundance of 159 proteins. This is the first shotgun proteomics study in wheat, providing important insights into protein responses to drought as well as identifying the largest number of wheat proteins (1,299) in a single study. The changes in the three cultivars at the different time points reflected their differing physiological responses to drought, with the two drought tolerant varieties (Excalibur and RAC875) differing in their protein responses. Excalibur lacked significant changes in proteins during the initial onset of the water deficit in contrast to RAC875 that had a large number of significant changes. All three cultivars had changes consistent with an increase in oxidative stress metabolism and reactive O2 species (ROS) scavenging capacity seen through increases in superoxide dismutases and catalases as well as ROS avoidance through the decreases in proteins involved in photosynthesis and the Calvin cycle. PMID:22639595
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Roles of Plasmalemma Aquaporin Gene StPIP1 in Enhancing Drought Tolerance in Potato
Wang, Li; Liu, Yuhui; Feng, Shoujiang; Yang, Jiangwei; Li, Dan; Zhang, Junlian
2017-01-01
Survival and mortality of plants in response to severe drought may be related to carbon starvation, but little is known about how plasma membrane intrinsic proteins may help alleviate the drought-induced damage. Here, we determined the roles of plasmalemma aquaporin gene in improving plant water status, maintaining carbon accumulation, and thereby enhancing drought tolerance. Seven StPIP1 transformed potato (Solanum tuberosum L.) lines (namely T1, T2…T7) were compared with non-transgenic control plant at molecule and whole-plant levels. The relative expression of StPIP1 gene was found in leaves, stems and roots, with the most abundant expression being in the roots. The transgenic lines T6 and T7 had the highest StPIP1 expression, averaging 7.2 times that of the control and the greatest differences occurred 48 h after mannitol osmotic stress treatment. Using an evaluation index to quantifying the degree of drought tolerance, we found that the StPIP1 transgenic lines T6 and T7 had the highest drought tolerance, averaging 8.5 times that of the control. Measured at 30 days in drought stress treatment, the control plant decreased net photosynthetic rate by 33 and 56%, respectively, under moderate and severe stresses; also decreased stomatal conductance by 39 and 65%; and lowered transpiration rate by 49 and 69%, compared to the no-stress treatment, whereas the transgenic lines T6 and T7 maintained a relatively stable level with slight decreases in these properties. The constitutive overexpression of StPIP1 in potato improved plant water use efficiency and increased nonstructural carbohydrate concentration, which helped alleviate carbon starvation and minimized the loss of biomass and tuber yield due to drought stress. We conclude that the expression of StPIPs improves overall water relations in the plant and helps maintain photosynthesis and stomatal conductance; these help minimize carbon starvation and enhance the whole plant tolerance to drought stress. PMID:28487712
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Lu, Shaoyun; Chen, Chuanhao; Wang, Zhongcheng; Guo, Zhenfei; Li, Haihang
2009-03-01
Eight somaclonal variants with enhanced drought tolerance were isolated from regenerated plants of triploid bermudagrass (Cynodon dactylon x Cynodon transvaalensis cv., TifEagle). Three of them (10-17, 89-02, 117-08) with strong drought tolerance were selected for investigations of physiological responses to drought stress. Compared to the parent control, TifEagle, the somaclonal variants had higher relative water contents and relative growth, and lower ion leakages in the greenhouse tests, while no difference in evapotranspirational water losses and soil water contents was observed between the variants and TifEagle. The variants also had less leaf firing in the field tests under drought stress. Superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activities decreased gradually in responses to drought stress in all plants and exhibited negative correlations with ion leakage, indicating that the declined activities of these antioxidant enzymes were associated with drought injury in the triploid bermudagrass. However, CAT activities were significantly higher in all three variants than in TifEagle during drought stress. Two variants, 10-17 and 89-02, also had significantly higher APX activities than TifEagle before and during the first 4 days of drought treatments. These two lines also showed higher SOD activities after prolonged drought stress. Proline, total soluble sugars and sucrose were accumulated under drought stress in all plants and exhibited positive correlations with ion leakage. More proline and sugars were accumulated in TifEagle than in the variants. The results indicated that higher activities of the antioxidant enzymes in the variants during drought stress are associated with their increased drought tolerance.
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Kuromori, Takashi; Fujita, Miki; Urano, Kaoru; Tanabata, Takanari; Sugimoto, Eriko; Shinozaki, Kazuo
2016-10-01
In addition to improving drought tolerance, improvement of water use efficiency is a major challenge in plant physiology. Due to their trade-off relationships, it is generally considered that achieving stress tolerance is incompatible with maintaining stable growth. Abscisic acid (ABA) is a key phytohormone that regulates the balance between intrinsic growth and environmental responses. Previously, we identified AtABCG25 as a cell-membrane ABA transporter that export ABA from the inside to the outside of cells. AtABCG25-overexpressing plants showed a lower transpiration phenotype without any growth retardation. Here, we dissected this useful trait using precise phenotyping approaches. AtABCG25 overexpression stimulated a local ABA response in guard cells. Furthermore, AtABCG25 overexpression enhanced drought tolerance, probably resulting from maintenance of water contents over the common threshold for survival after drought stress treatment. Finally, we observed enhanced water use efficiency by overexpression of AtABCG25, in addition to drought tolerance. These results were consistent with the function of AtABCG25 as an ABA efflux transporter. This unique trait may be generally useful for improving the water use efficiency and drought tolerance of plants. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
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A multi-structural and multi-functional integrated fog collection system in cactus
Ju, Jie; Bai, Hao; Zheng, Yongmei; Zhao, Tianyi; Fang, Ruochen; Jiang, Lei
2012-01-01
Multiple biological structures have demonstrated fog collection abilities, such as beetle backs with bumps and spider silks with periodic spindle-knots and joints. Many Cactaceae species live in arid environments and are extremely drought-tolerant. Here we report that one of the survival systems of the cactus Opuntia microdasys lies in its efficient fog collection system. This unique system is composed of well-distributed clusters of conical spines and trichomes on the cactus stem; each spine contains three integrated parts that have different roles in the fog collection process according to their surface structural features. The gradient of the Laplace pressure, the gradient of the surface-free energy and multi-function integration endow the cactus with an efficient fog collection system. Investigations of the structure–function relationship in this system may help us to design novel materials and devices to collect water from fog with high efficiencies. PMID:23212376
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A multi-structural and multi-functional integrated fog collection system in cactus.
Ju, Jie; Bai, Hao; Zheng, Yongmei; Zhao, Tianyi; Fang, Ruochen; Jiang, Lei
2012-01-01
Multiple biological structures have demonstrated fog collection abilities, such as beetle backs with bumps and spider silks with periodic spindle-knots and joints. Many Cactaceae species live in arid environments and are extremely drought-tolerant. Here we report that one of the survival systems of the cactus Opuntia microdasys lies in its efficient fog collection system. This unique system is composed of well-distributed clusters of conical spines and trichomes on the cactus stem; each spine contains three integrated parts that have different roles in the fog collection process according to their surface structural features. The gradient of the Laplace pressure, the gradient of the surface-free energy and multi-function integration endow the cactus with an efficient fog collection system. Investigations of the structure-function relationship in this system may help us to design novel materials and devices to collect water from fog with high efficiencies.
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Iurlaro, Andrea; De Caroli, Monica; Sabella, Erika; De Pascali, Mariarosaria; Rampino, Patrizia; De Bellis, Luigi; Perrotta, Carla; Dalessandro, Giuseppe; Piro, Gabriella; Fry, Stephen C.; Lenucci, Marcello S.
2016-01-01
Heat and drought stress have emerged as major constraints for durum wheat production. In the Mediterranean area, their negative effect on crop productivity is expected to be exacerbated by the occurring climate change. Xyloglucan endotransglucosylase/hydrolases (XTHs) are chief enzymes in cell wall remodeling, whose relevance in cell expansion and morphogenesis suggests a central role in stress responses. In this work the potential role of XTHs in abiotic stress tolerance was investigated in durum wheat. The separate effects of dehydration and heat exposure on XTH expression and its endotransglucosylase (XET) in vitro activity and in vivo action have been monitored, up to 24 h, in the apical and sub-apical root regions and shoots excised from 3-day-old seedlings of durum wheat cultivars differing in stress susceptibility/tolerance. Dehydration and heat stress differentially influence the XTH expression profiles and the activity and action of XET in the wheat seedlings, depending on the degree of susceptibility/tolerance of the cultivars, the organ, the topological region of the root and, within the root, on the gradient of cell differentiation. The root apical region was the zone mainly affected by both treatments in all assayed cultivars, while no change in XET activity was observed at shoot level, irrespective of susceptibility/tolerance, confirming the pivotal role of the root in stress perception, signaling, and response. Conflicting effects were observed depending on stress type: dehydration evoked an overall increase, at least in the apical region of the root, of XET activity and action, while a significant inhibition was caused by heat treatment in most cultivars. The data suggest that differential changes in XET action in defined portions of the root of young durum wheat seedlings may have a role as a response to drought and heat stress, thus contributing to seedling survival and crop establishment. A thorough understanding of the mechanisms underlying these variations could represent the theoretical basis for implementing breeding strategies to develop new highly productive hybrids adapted to future climate scenarios. PMID:27891140
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Graham, Eric A; Andrade, Jose Luis
2004-05-01
Vertical stratification of epiphytes generally has not been reported for dry forests. For two epiphytic Crassulacean acid metabolism bromeliads that segregate vertically, it was hypothesized that different potentials for photoprotection or shade tolerance rather than drought tolerance is responsible for the observed stratification. The light environment, capacity for photoprotection, germination response to light quality, and responses to light and drought were thus examined for Tillandsia brachycaulos and T. elongata. Vertical and light-environment distributions differed for the two species but photoprotection and photodamage did not where they occurred at similar field locations; T. brachycaulos had a higher pigment acclimation to light. Tillandsia brachycaulos had higher acid accumulation under low light as opposed to T. elongata, which responded similarly to all but the highest light treatment. Tillandsia brachycaulos maintained positive total daily net CO(2) uptake through 30 d of drought; T. elongata had a total daily net CO(2) loss after 7 d of drought. The vertical stratification was most likely the result of the sensitivity to drought of T. elongata rather than differences in photoprotection or shade tolerance between the two species. Tillandsia elongata occurs in more exposed locations, which may be advantageous for rainfall interception and dew formation.
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USDA-ARS?s Scientific Manuscript database
Drought stress is a major factor which contributes to disease susceptibility and yield loss in agricultural crops. To identify drought responsive proteins and explore metabolic pathways involved in maize tolerance to drought stress, two lines (B73 and Lo964) with contrasting drought sensitivity were...
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NASA Astrophysics Data System (ADS)
Banavath, Jayanna N.; Chakradhar, Thammineni; Pandit, Varakumar; Konduru, Sravani; Guduru, Krishna K.; Akila, Chandra S.; Podha, Sudhakar; Puli, Chandra O. R.
2018-03-01
Peanut is an important oilseed and food legume cultivated as a rain-fed crop in semi-arid tropics. Drought and high salinity are the major abiotic stresses limiting the peanut productivity in this region. Development of drought and salt tolerant peanut varieties with improved yield potential using biotechnological approach is highly desirable to improve the peanut productivity in marginal geographies. As abiotic stress tolerance and yield represent complex traits, engineering of regulatory genes to produce abiotic stress-resilient transgenic crops appears to be a viable approach. In the present study, we developed transgenic peanut plants expressing an Arabidopsis homeodomain-leucine zipper transcription factor (AtHDG11) under stress inducible rd29Apromoter. A stress-inducible expression of AtHDG11 in three independent homozygous transgenic peanut lines resulted in improved drought and salt tolerance through up-regulation of known stress responsive genes(LEA, HSP70, Cu/Zn SOD, APX, P5CS, NCED1, RRS5, ERF1, NAC4, MIPS, Aquaporin, TIP, ELIP ) in the stress gene network , antioxidative enzymes, free proline along with improved water use efficiency traits such as longer root system, reduced stomatal density, higher chlorophyll content, increased specific leaf area, improved photosynthetic rates and increased intrinsic instantaneous WUE. Transgenic peanut plants displayed high yield compared to non-transgenic plants under both drought and salt stress conditions. Holistically, our study demonstrates the potentiality of stress-induced expression of AtHDG11 to improve the drought, salt tolerance in peanut.
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Deciphering drought-induced metabolic responses and regulation in developing maize kernels.
Yang, Liming; Fountain, Jake C; Ji, Pingsheng; Ni, Xinzhi; Chen, Sixue; Lee, Robert D; Kemerait, Robert C; Guo, Baozhu
2018-02-12
Drought stress conditions decrease maize growth and yield, and aggravate preharvest aflatoxin contamination. While several studies have been performed on mature kernels responding to drought stress, the metabolic profiles of developing kernels are not as well characterized, particularly in germplasm with contrasting resistance to both drought and mycotoxin contamination. Here, following screening for drought tolerance, a drought-sensitive line, B73, and a drought-tolerant line, Lo964, were selected and stressed beginning at 14 days after pollination. Developing kernels were sampled 7 and 14 days after drought induction (DAI) from both stressed and irrigated plants. Comparative biochemical and metabolomic analyses profiled 409 differentially accumulated metabolites. Multivariate statistics and pathway analyses showed that drought stress induced an accumulation of simple sugars and polyunsaturated fatty acids and a decrease in amines, polyamines and dipeptides in B73. Conversely, sphingolipid, sterol, phenylpropanoid and dipeptide metabolites accumulated in Lo964 under drought stress. Drought stress also resulted in the greater accumulation of reactive oxygen species (ROS) and aflatoxin in kernels of B73 in comparison with Lo964 implying a correlation in their production. Overall, field drought treatments disordered a cascade of normal metabolic programming during development of maize kernels and subsequently caused oxidative stress. The glutathione and urea cycles along with the metabolism of carbohydrates and lipids for osmoprotection, membrane maintenance and antioxidant protection were central among the drought stress responses observed in developing kernels. These results also provide novel targets to enhance host drought tolerance and disease resistance through the use of biotechnologies such as transgenics and genome editing. © 2018 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.
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Alsdurf, Jacob; Anderson, Cynthia; Siemens, David H.
2016-01-01
Genetic variation gives plants the potential to adapt to stressful environments that often exist beyond their geographic range limits. However, various genetic, physiological or developmental constraints might prevent the process of adaptation. Alternatively, environmentally induced epigenetic changes might sustain populations for several generations in stressful areas across range boundaries, but previous work on Boechera stricta, an upland mustard closely related to Arabidopsis, documented a drought-induced trans-generational plastic trade-off that could contribute to range limit development. Offspring of parents who were drought treated had higher drought tolerance, but lower levels of glucosinolate toxins. Both drought tolerance and defence are thought to be needed to expand the range to lower elevations. Here, we used methylation-sensitive amplified fragment length polymorphisms to determine whether environmentally induced DNA methylation and thus epigenetics could be a mechanism involved in the observed trans-generational plastic trade-off. We compared 110 offspring from the same self-fertilizing lineages whose parents were exposed to experimental drought stress treatments in the laboratory. Using three primer combinations, 643 polymorphic epi-loci were detected. Discriminant function analysis (DFA) on the amount of methylation detected resulted in significant combinations of epi-loci that distinguished the parent drought treatments in the offspring. Principal component (PC) and univariate association analyses also detected the significant differences, even after controlling for lineage, planting flat, developmental differences and multiple testing. Univariate tests also indicated significant associations between the amount of methylation and drought tolerance or glucosinolate toxin concentration. One epi-locus that was implicated in DFA, PC and univariate association analysis may be directly involved in the trade-off because increased methylation at this site on the genome decreased drought tolerance, but increased glucosinolate concentration. PMID:26685218
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Muchero, Wellington; Ehlers, Jeffrey D; Roberts, Philip A
2010-02-01
Quantitative trait loci (QTL) studies provide insight into the complexity of drought tolerance mechanisms. Molecular markers used in these studies also allow for marker-assisted selection (MAS) in breeding programs, enabling transfer of genetic factors between breeding lines without complete knowledge of their exact nature. However, potential for recombination between markers and target genes limit the utility of MAS-based strategies. Candidate gene mapping offers an alternative solution to identify trait determinants underlying QTL of interest. Here, we used restriction site polymorphisms to investigate co-location of candidate genes with QTL for seedling drought stress-induced premature senescence identified previously in cowpea. Genomic DNA isolated from 113 F(2:8) RILs of drought-tolerant IT93K503-1 and drought susceptible CB46 genotypes was digested with combinations of EcoR1 and HpaII, Mse1, or Msp1 restriction enzymes and amplified with primers designed from 13 drought-responsive cDNAs. JoinMap 3.0 and MapQTL 4.0 software were used to incorporate polymorphic markers onto the AFLP map and to analyze their association with the drought response QTL. Seven markers co-located with peaks of previously identified QTL. Isolation, sequencing, and blast analysis of these markers confirmed their significant homology with drought or other abiotic stress-induced expressed sequence tags (EST) from cowpea and other plant systems. Further, homology with coding sequences for a multidrug resistance protein 3 and a photosystem I assembly protein ycf3 was revealed in two of these candidates. These results provide a platform for the identification and characterization of genetic trait determinants underlying seedling drought tolerance in cowpea.
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microRNAs Associated with Drought Response in the Bioenergy Crop Sugarcane (Saccharum spp.)
Vilela, Romel Duarte; Costa, Gustavo Gilson Lacerda; Dias, Lara Isys; Endres, Laurício; Menossi, Marcelo
2012-01-01
Sugarcane (Saccharum spp.) is one of the most important crops in the world. Drought stress is a major abiotic stress factor that significantly reduces sugarcane yields. However the gene network that mediates plant responses to water stress remains largely unknown in several crop species. Although several microRNAs that mediate post-transcriptional regulation during water stress have been described in other species, the role of the sugarcane microRNAs during drought stress has not been studied. The objective of this work was to identify sugarcane miRNAs that are differentially expressed under drought stress and to correlate this expression with the behavior of two sugarcane cultivars with different drought tolerances. The sugarcane cultivars RB867515 (higher drought tolerance) and RB855536 (lower drought tolerance) were cultivated in a greenhouse for three months and then subjected to drought for 2, 4, 6 or 8 days. By deep sequencing of small RNAs, we were able to identify 18 miRNA families. Among all of the miRNAs thus identified, seven were differentially expressed during drought. Six of these miRNAs were differentially expressed at two days of stress, and five miRNAs were differentially expressed at four days. The expression levels of five miRNAs (ssp-miR164, ssp-miR394, ssp-miR397, ssp-miR399-seq 1 and miR528) were validated by RT-qPCR (quantitative reverse transcriptase PCR). Six precursors and the targets of the differentially expressed miRNA were predicted using an in silico approach and validated by RT-qPCR; many of these targets may play important roles in drought tolerance. These findings constitute a significant increase in the number of identified miRNAs in sugarcane and contribute to the elucidation of the complex regulatory network that is activated by drought stress. PMID:23071617
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NASA Astrophysics Data System (ADS)
Kulkarni, Manoj; Soolanayakanahally, Raju; Ogawa, Satoshi; Uga, Yusaku; Selvaraj, Michael G.; Kagale, Sateesh
2017-12-01
Abiotic stresses such as drought, heat, salinity and flooding threaten global food security. Crop genetic improvement with increased resilience to abiotic stresses is a critical component of crop breeding strategies. Wheat is an important cereal crop and a staple food source globally. Enhanced drought tolerance in wheat is critical for sustainable food production and global food security. Recent advances in drought tolerance research have uncovered many key genes and transcription regulators governing morpho-physiological traits. Genes controlling root architecture and stomatal development play an important role in soil moisture extraction and its retention, and therefore have been targets of molecular breeding strategies for improving drought tolerance. In this systematic review, we have summarized evidence of beneficial contributions of root and stomatal traits to plant adaptation to drought stress. Specifically, we discuss a few key genes such as DRO1 in rice and ERECTA in Arabidopsis and rice that were identified to be the enhancers of drought tolerance via regulation of root traits and transpiration efficiency. Additionally, we highlight several transcription factor families, such as ERF (ethylene response factors), DREB (dehydration responsive element binding), ZFP (zinc finger proteins), WRKY and MYB that were identified to be both positive and negative regulators of drought responses in wheat, rice, maize and/or Arabidopsis. The overall aim of this review was to provide an overview of candidate genes that have been tested as regulators of drought response in plants. The lack of a reference genome sequence for wheat and nontransgenic approaches for manipulation of gene functions in the past had impeded high-resolution interrogation of functional elements, including genes and QTLs, and their application in cultivar improvement. The recent developments in wheat genomics and reverse genetics, including the availability of a gold-standard reference genome sequence and advent genome editing technologies, are expected to aid in deciphering of the functional roles of genes and regulatory networks underlying adaptive phenological traits, and utilizing the outcomes of such studies in developing drought tolerance cultivars.
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Kulkarni, Manoj; Soolanayakanahally, Raju; Ogawa, Satoshi; Uga, Yusaku; Selvaraj, Michael G; Kagale, Sateesh
2017-01-01
Abiotic stresses such as, drought, heat, salinity, and flooding threaten global food security. Crop genetic improvement with increased resilience to abiotic stresses is a critical component of crop breeding strategies. Wheat is an important cereal crop and a staple food source globally. Enhanced drought tolerance in wheat is critical for sustainable food production and global food security. Recent advances in drought tolerance research have uncovered many key genes and transcription regulators governing morpho-physiological traits. Genes controlling root architecture and stomatal development play an important role in soil moisture extraction and its retention, and therefore have been targets of molecular breeding strategies for improving drought tolerance. In this systematic review, we have summarized evidence of beneficial contributions of root and stomatal traits to plant adaptation to drought stress. Specifically, we discuss a few key genes such as, DRO1 in rice and ERECTA in Arabidopsis and rice that were identified to be the enhancers of drought tolerance via regulation of root traits and transpiration efficiency. Additionally, we highlight several transcription factor families, such as, ERF (ethylene response factors), DREB (dehydration responsive element binding), ZFP (zinc finger proteins), WRKY, and MYB that were identified to be both positive and negative regulators of drought responses in wheat, rice, maize, and/or Arabidopsis. The overall aim of this review is to provide an overview of candidate genes that have been identified as regulators of drought response in plants. The lack of a reference genome sequence for wheat and non-transgenic approaches for manipulation of gene functions in wheat in the past had impeded high-resolution interrogation of functional elements, including genes and QTLs, and their application in cultivar improvement. The recent developments in wheat genomics and reverse genetics, including the availability of a gold-standard reference genome sequence and advent of genome editing technologies, are expected to aid in deciphering of the functional roles of genes and regulatory networks underlying adaptive phenological traits, and utilizing the outcomes of such studies in developing drought tolerant cultivars.
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Aravind, Jayaraman; Rinku, Sharma; Pooja, Banduni; Shikha, Mittal; Kaliyugam, Shiriga; Mallikarjuna, Mallana Gowdra; Kumar, Arun; Rao, Atmakuri Ramakrishna; Nepolean, Thirunavukkarasu
2017-01-01
MicroRNA-mediated gene regulation plays a crucial role in controlling drought tolerance. In the present investigation, 13 drought-associated miRNA families consisting of 65 members and regulating 42 unique target mRNAs were identified from drought-associated microarray expression data in maize and were subjected to structural and functional characterization. The largest number of members (14) was found in the zma-miR166 and zma-miR395 families, with several targets. However, zma-miR160, zma-miR390, zma-miR393, and zma-miR2275 each showed a single target. Twenty-three major drought-responsive cis-regulatory elements were found in the upstream regions of miRNAs. Many drought-related transcription factors, such as GAMYB, HD-Zip III, and NAC, were associated with the target mRNAs. Furthermore, two contrasting subtropical maize genotypes (tolerant: HKI-1532 and sensitive: V-372) were used to understand the miRNA-assisted regulation of target mRNA under drought stress. Approximately 35 and 31% of miRNAs were up-regulated in HKI-1532 and V-372, respectively. The up-regulation of target mRNAs was as high as 14.2% in HKI-1532 but was only 2.38% in V-372. The expression patterns of miRNA-target mRNA pairs were classified into four different types: Type I- up-regulation, Type II- down-regulation, Type III- neutral regulation, and Type IV- opposite regulation. HKI-1532 displayed 46 Type I, 13 Type II, and 23 Type III patterns, whereas V-372 had mostly Type IV interactions (151). A low level of negative regulations of miRNA associated with a higher level of mRNA activity in the tolerant genotype helped to maintain crucial biological functions such as ABA signaling, the auxin response pathway, the light-responsive pathway and endosperm expression under stress conditions, thereby leading to drought tolerance. Our study identified candidate miRNAs and mRNAs operating in important pathways under drought stress conditions, and these candidates will be useful in the development of drought-tolerant maize hybrids. PMID:28626466
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Inter-genotypic differences in drought tolerance of maritime pine are modified by elevated [CO2].
Sánchez-Gómez, David; Mancha, José A; Cervera, M Teresa; Aranda, Ismael
2017-10-17
Despite the importance of growth [CO 2 ] and water availability for tree growth and survival, little information is available on how the interplay of these two factors can shape intraspecific patterns of functional variation in tree species, particularly for conifers. The main objective of the study was to test whether the range of realized drought tolerance within the species can be affected by elevated [CO 2 ]. Intraspecific variability in leaf gas exchange, growth rate and other leaf functional traits were studied in clones of maritime pine. A factorial experiment including water availability, growth [CO 2 ] and four different genotypes was conducted in growth rooms. A 'water deficit' treatment was imposed by applying a cycle of progressive soil water depletion and recovery at two levels of growth [CO 2 ]: 'ambient [CO 2 ]' (aCO 2 400 μmol mol -1 ) and 'elevated [CO 2 ]' (eCO 2 800 μmol mol -1 ). eCO2 had a neutral effect on the impact of drought on growth and leaf gas exchange of the most drought-sensitive genotypes while it aggravated the impact of drought on the most drought-tolerant genotypes at aCO2. Thus, eCO2 attenuated genotypic differences in drought tolerance as compared with those observed at aCO2. Genotypic variation at both levels of growth [CO2] was found in specific leaf area and leaf nitrogen content but not in other physiological leaf traits such as intrinsic water use efficiency and leaf osmotic potential. eCO2 increased Δ 13 C but had no significant effect on δ 18 O. This effect did not interact with the impact of drought, which increased δ 18 O and decreased Δ 13 C. Nevertheless, correlations between Δ 13 C and δ 18 O indicated the non-stomatal component of water use efficiency in this species can be particularly sensitive to drought. Evidence from this study suggests elevated [CO 2 ] can modify current ranges of drought tolerance within tree species. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com
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Sehgal, Akanksha; Sita, Kumari; Bhandari, Kalpna; Kumar, Shiv; Kumar, Jitendra; Vara Prasad, P V; Siddique, Kadambot H M; Nayyar, Harsh
2018-05-09
Terminal droughts, along with high temperatures, are becoming more frequent to strongly influence the seed development in cool-season pulses like lentil. In the present study, the lentil plants growing outdoors under natural environment were subjected to following treatments at the time of seed filling till maturity: (a) 28/23 °C day/night temperature as controls; (b) drought stressed, plants maintained at 50% field capacity, under the same growth conditions as in a; (c) heat stressed, 33/28 °C day/night temperature, under the same growth conditions as in a; and (d) drought + heat stressed, plants at 50% field capacity, 33/28 °C day/night temperature, under the same growth conditions as in (a). Both heat and drought resulted in marked reduction in the rate and duration of seed filling to decrease the final seed size; drought resulted in more damage than heat stress; combined stresses accentuated the damage to seed starch, storage proteins and their fractions, minerals, and several amino acids. Comparison of a drought-tolerant and a drought-sensitive genotype indicated the former type showed significantly less damage to various components of seeds, under drought as well as heat stress suggesting a cross tolerance, which was linked to its (drought tolerant) better capacity to retain more water in leaves and hence more photo-assimilation ability, compared with drought-sensitive genotype. © 2018 John Wiley & Sons Ltd.
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Chen, Juan; Fan, Lei; Du, Ya; Zhu, Weining; Tang, Ziqin; Li, Na; Zhang, Dapeng; Zhang, Linsheng
2016-11-01
Drought stress is a major factor limiting wheat growth and productivity. Late embryogenesis abundant (LEA) proteins are tolerant to water-related stress. To reveal the regulatory mechanisms of LEA proteins under drought stress, we cloned a novel group 3 LEA gene, namely, TaDlea3, from wheat (Triticum aestivum L.) Shaanhe 6. Subcellular localization assay showed that TaDlea3 protein accumulated in the cytoplasm. Quantitative real-time polymerase chain reaction results revealed that TaDlea3 expression was induced by drought stress. Western blot results indicated that TaDlea3 protein expression gradually increased with drought stress during four different developmental stages. Under normal conditions, no obvious phenotype difference was observed between the transgenic and wild-type seedlings. Meanwhile, the overexpression of TaDlea3 in Arabidopsis resulted in enhanced tolerance to drought stress, as determined by the assessment of antioxidant enzyme activities. Our results provide a basis for highly detailed functional analyses of LEA proteins and offer a promising approach for improving the tolerances of wheat cultivars to drought stress through genetic engineering. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
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Martínez, Luisa M; Fernández-Ocaña, Ana; Rey, Pedro J; Salido, Teresa; Amil-Ruiz, Francisco; Manzaneda, Antonio J
2018-06-08
Some polyploid species show enhanced physiological tolerance to drought compared with their progenitors. However, very few studies have examined the consistency of physiological drought response between genetically differentiated natural polyploid populations, which is key to evaluation of the importance of adaptive evolution after polyploidization in those systems where drought exerts a selective pressure. A comparative functional approach was used to investigate differentiation of drought-tolerance-related traits in the Brachypodium species complex, a model system for grass polyploid adaptive speciation and functional genomics that comprises three closely related annual species: the two diploid parents, B. distachyon and B. stacei, and the allotetraploid derived from them, B. hybridum. Differentiation of drought-tolerance-related traits between ten genetically distinct B. hybridum populations and its ecological correlates was further analysed. The functional drought response is overall well differentiated between Brachypodium species. Brachypodium hybridum allotetraploids showed a transgressive expression pattern in leaf phytohormone content in response to drought. In contrast, other B. hybridum physiological traits correlated to B. stacei ones. Particularly, proline and water content were the traits that best discriminated these species from B. distachyon under drought. After polyploid formation and/or colonization, B. hybridum populations have adaptively diverged physiologically and genetically in response to variations in aridity.
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Hussain, Hafiz A.; Hussain, Saddam; Khaliq, Abdul; Ashraf, Umair; Anjum, Shakeel A.; Men, Shengnan; Wang, Longchang
2018-01-01
Plants face a combination of different abiotic stresses under field conditions which are lethal to plant growth and production. Simultaneous occurrence of chilling and drought stresses in plants due to the drastic and rapid global climate changes, can alter the morphological, physiological and molecular responses. Both these stresses adversely affect the plant growth and yields due to physical damages, physiological and biochemical disruptions, and molecular changes. In general, the co-occurrence of chilling and drought combination is even worse for crop production rather than an individual stress condition. Plants attain various common and different physiological and molecular protective approaches for tolerance under chilling and drought stresses. Nevertheless, plant responses to a combination of chilling and drought stresses are unique from those to individual stress. In the present review, we summarized the recent evidence on plant responses to chilling and drought stresses on shared as well as unique basis and tried to find a common thread potentially underlying these responses. We addressed the possible cross talk between plant responses to these stresses and discussed the potential management strategies for regulating the mechanisms of plant tolerance to drought and/or chilling stresses. To date, various novel approaches have been tested in minimizing the negative effects of combine stresses. Despite of the main improvements there is still a big room for improvement in combination of drought and chilling tolerance. Thus, future researches particularly using biotechnological and molecular approaches should be carried out to develop genetically engineered plants with enhanced tolerance against these stress factors. PMID:29692787
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Zhu, Zhangsheng; Sun, Binmei; Xu, Xiaoxia; Chen, Hao; Zou, Lifang; Chen, Guoju; Cao, Bihao; Chen, Changming; Lei, Jianjun
2016-01-01
Plants are constantly challenged by environmental stresses, including drought and high salinity. Improvement of drought and osmotic stress tolerance without yield decrease has been a great challenge in crop improvement. The Arabidopsis ENHANCED DROUGHT TOLERANCE1/HOMEODOMAIN GLABROUS11 (AtEDT1/HDG11), a protein of the class IV HD-Zip family, has been demonstrated to significantly improve drought tolerance in Arabidopsis, rice, and pepper. Here, we report that AtEDT1/HDG11 confers drought and osmotic stress tolerance in the Chinese kale. AtEDT1/HDG11-overexpression lines exhibit auxin-overproduction phenotypes, such as long hypocotyls, tall stems, more root hairs, and a larger root system architecture. Compared with the untransformed control, transgenic lines have significantly reduced stomatal density. In the leaves of transgenic Chinese kale plants, proline (Pro) content and reactive oxygen species-scavenging enzyme activity was significantly increased after drought and osmotic stress, particularly compared to wild kale. More importantly, AtEDT1/HDG11-overexpression leads to abscisic acid (ABA) hypersensitivity, resulting in ABA inhibitor germination and induced stomatal closure. Consistent with observed phenotypes, the expression levels of auxin, ABA, and stress-related genes were also altered under both normal and/or stress conditions. Further analysis showed that AtEDT1/HDG11, as a transcription factor, can target the auxin biosynthesis gene YUCC6 and ABA response genes ABI3 and ABI5. Collectively, our results provide a new insight into the role of AtEDT1/HDG11 in enhancing abiotic stress resistance through auxin- and ABA-mediated signaling response in Chinese kale. PMID:27625663
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Zhu, Zhangsheng; Sun, Binmei; Xu, Xiaoxia; Chen, Hao; Zou, Lifang; Chen, Guoju; Cao, Bihao; Chen, Changming; Lei, Jianjun
2016-01-01
Plants are constantly challenged by environmental stresses, including drought and high salinity. Improvement of drought and osmotic stress tolerance without yield decrease has been a great challenge in crop improvement. The Arabidopsis ENHANCED DROUGHT TOLERANCE1/HOMEODOMAIN GLABROUS11 (AtEDT1/HDG11), a protein of the class IV HD-Zip family, has been demonstrated to significantly improve drought tolerance in Arabidopsis, rice, and pepper. Here, we report that AtEDT1/HDG11 confers drought and osmotic stress tolerance in the Chinese kale. AtEDT1/HDG11-overexpression lines exhibit auxin-overproduction phenotypes, such as long hypocotyls, tall stems, more root hairs, and a larger root system architecture. Compared with the untransformed control, transgenic lines have significantly reduced stomatal density. In the leaves of transgenic Chinese kale plants, proline (Pro) content and reactive oxygen species-scavenging enzyme activity was significantly increased after drought and osmotic stress, particularly compared to wild kale. More importantly, AtEDT1/HDG11-overexpression leads to abscisic acid (ABA) hypersensitivity, resulting in ABA inhibitor germination and induced stomatal closure. Consistent with observed phenotypes, the expression levels of auxin, ABA, and stress-related genes were also altered under both normal and/or stress conditions. Further analysis showed that AtEDT1/HDG11, as a transcription factor, can target the auxin biosynthesis gene YUCC6 and ABA response genes ABI3 and ABI5. Collectively, our results provide a new insight into the role of AtEDT1/HDG11 in enhancing abiotic stress resistance through auxin- and ABA-mediated signaling response in Chinese kale.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Dong, Yan; Liaoning Forestry Vocational-Technical College, Shenyang 110101; Wang, Congpeng
2014-07-18
Highlights: • PebHLH35 is firstly cloned from Populus euphratica and characterized its functions. • PebHLH35 is important for earlier seedling establishment and vegetative growth. • PebHLH35 enhances tolerance to drought by regulating growth. • PebHLH35 enhances tolerance to drought by regulating stomatal development. • PebHLH35 enhances tolerance to drought by regulating photosynthesis and transpiration. - Abstract: Plant basic helix-loop-helix (bHLH) transcription factors (TFs) are involved in a variety of physiological processes including the regulation of plant responses to various abiotic stresses. However, few drought-responsive bHLH family members in Populus have been reported. In this study, a novel bHLH gene (PebHLH35)more » was cloned from Populus euphratica. Expression analysis in P. euphratica revealed that PebHLH35 was induced by drought and abscisic acid. Subcellular localization studies using a PebHLH35-GFP fusion showed that the protein was localized to the nucleus. Ectopic overexpression of PebHLH35 in Arabidopsis resulted in a longer primary root, more leaves, and a greater leaf area under well-watered conditions compared with vector control plants. Notably, PebHLH35 overexpression lines showed enhanced tolerance to water-deficit stress. This finding was supported by anatomical and physiological analyses, which revealed a reduced stomatal density, stomatal aperture, transpiration rate, and water loss, and a higher chlorophyll content and photosynthetic rate. Our results suggest that PebHLH35 functions as a positive regulator of drought stress responses by regulating stomatal density, stomatal aperture, photosynthesis and growth.« less
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Priyanka, B; Sekhar, K; Sunita, T; Reddy, V D; Rao, Khareedu Venkateswara
2010-03-01
Pigeonpea, a major grain legume crop with remarkable drought tolerance traits, has been used for the isolation of stress-responsive genes. Herein, we report generation of ESTs, transcript profiles of selected genes and validation of candidate genes obtained from the subtracted cDNA libraries of pigeonpea plants subjected to PEG/water-deficit stress conditions. Cluster analysis of 124 selected ESTs yielded 75 high-quality ESTs. Homology searches disclosed that 55 ESTs share significant similarity with the known/putative proteins or ESTs available in the databases. These ESTs were characterized and genes relevant to the specific physiological processes were identified. Of the 75 ESTs obtained from the cDNA libraries of drought-stressed plants, 20 ESTs proved to be unique to the pigeonpea. These sequences are envisaged to serve as a potential source of stress-inducible genes of the drought stress-response transcriptome, and hence may be used for deciphering the mechanism of drought tolerance of the pigeonpea. Expression profiles of selected genes revealed increased levels of m-RNA transcripts in pigeonpea plants subjected to different abiotic stresses. Transgenic Arabidopsis lines, expressing Cajanus cajan hybrid-proline-rich protein (CcHyPRP), C. cajan cyclophilin (CcCYP) and C. cajan cold and drought regulatory (CcCDR) genes, exhibited marked tolerance, increased plant biomass and enhanced photosynthetic rates under PEG/NaCl/cold/heat stress conditions. This study represents the first report dealing with the isolation of drought-specific ESTs, transcriptome analysis and functional validation of drought-responsive genes of the pigeonpea. These genes, as such, hold promise for engineering crop plants bestowed with tolerance to major abiotic stresses.
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Modeling Preference and Willingness to Pay for Drought Tolerance (DT) in Maize in Rural Zimbabwe.
Kassie, Girma T; Abdulai, Awudu; Greene, William H; Shiferaw, Bekele; Abate, Tsedeke; Tarekegne, Amsal; Sutcliffe, Chloe
2017-06-01
Maize plays a leading role in the food security of millions in southern Africa, yet it is highly vulnerable to the moisture stress brought about by the erratic rainfall patterns that characterize weather systems in the area. Developing and making drought-tolerant maize varieties available to farmers in the region has thus long been a key goal on the regional development agenda. Farm-level adoption of these varieties, however, depends on local perceptions of the value they add, along with willingness to pay (WTP) for it. Focusing on Zimbabwe, this research aimed at estimating the implicit prices farmers are willing to pay for drought tolerance in maize compared to other preferred traits. Using a choice experiment framework, we generated 12,600 observations from a random sample of 1,400 households in communal areas within 14 districts of Zimbabwe. Taste parameters and heterogeneities were estimated using the generalized multinomial logit model (G-MNL). The results reveal drought tolerance, grain yield, covered cob tip, cob size, and semi-flint texture to be the most preferred traits by farm households in Zimbabwe. The WTP estimates show that farmers are willing to pay a premium for drought tolerance equal to 2.56, 7, 3.2, and 5 times higher than for an additional ton of yield per acre, bigger cob size, larger grain size, and covered cob tip, respectively. We suggest designing and implementing innovative ways of promoting DT maize along with awareness-raising activities to enhance contextual understandings of drought and drought risk to speed adoption of new DT maize varieties by risk-prone farming communities. Given the high level of rural literacy and the high rate of adoption of improved maize, trait-based promotion and marketing of varieties constitutes the right strategy.
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Tabassum, Tahira; Farooq, Muhammad; Ahmad, Riaz; Zohaib, Ali; Wahid, Abdul
2017-09-01
This study was conducted to evaluate the potential of seed priming following terminal drought on tolerance against salt stress in bread wheat. Drought was imposed in field sown wheat at reproductive stage (BBCH growth stage 49) and was maintained till physiological maturity (BBCH growth stage 83). Seeds of bread wheat, collected from crop raised under terminal drought and/or well-watered conditions, were subjected to hydropriming and osmopriming (with 1.5% CaCl 2 ) and were sown in soil-filled pots. After stand establishment, salt stress treatments viz. 10 mM NaCl (control) and 100 mM NaCl were imposed. Seed from terminal drought stressed source had less fat (5%), and more fibers (11%), proteins (22%) and total soluble phenolics (514%) than well-watered seed source. Salt stress reduced the plant growth, perturbed water relations and decreased yield. However, an increase in osmolytes accumulation (4-18%), malondialdehyde (MDA) (27-35%) and tissue Na + contents (149-332%) was observed under salt stress. The seeds collected from drought stressed crop had better tolerance against salt stress as indicated by better yield (28%), improved water relations (3-18%), osmolytes accumulation (21-33%), and less MDA (8%) and Na contents (35%) than progeny of well-watered crop. Seed priming, osmopriming in particular, further improved the tolerance against salt stress through improvement in leaf area, water relations, leaf proline, glycine betaine and grain yield while lowering MDA and Na + contents. In conclusion, changed seed composition during terminal drought and seed priming improved the salt tolerance in wheat by modulating the water relations, osmolytes accumulation and lipid peroxidation. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
De Kauwe, M. G.; Zhou, S. -X.; Medlyn, B. E.
Future climate change has the potential to increase drought in many regions of the globe, making it essential that land surface models (LSMs) used in coupled climate models realistically capture the drought responses of vegetation. Recent data syntheses show that drought sensitivity varies considerably among plants from different climate zones, but state-of-the-art LSMs currently assume the same drought sensitivity for all vegetation. We tested whether variable drought sensitivities are needed to explain the observed large-scale patterns of drought impact on the carbon, water and energy fluxes. We implemented data-driven drought sensitivities in the Community Atmosphere Biosphere Land Exchange (CABLE) LSMmore » and evaluated alternative sensitivities across a latitudinal gradient in Europe during the 2003 heatwave. The model predicted an overly abrupt onset of drought unless average soil water potential was calculated with dynamic weighting across soil layers. We found that high drought sensitivity at the most mesic sites, and low drought sensitivity at the most xeric sites, was necessary to accurately model responses during drought. Furthermore, our results indicate that LSMs will over-estimate drought impacts in drier climates unless different sensitivity of vegetation to drought is taken into account.« less
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De Kauwe, M. G.; Zhou, S. -X.; Medlyn, B. E.; ...
2015-12-21
Future climate change has the potential to increase drought in many regions of the globe, making it essential that land surface models (LSMs) used in coupled climate models realistically capture the drought responses of vegetation. Recent data syntheses show that drought sensitivity varies considerably among plants from different climate zones, but state-of-the-art LSMs currently assume the same drought sensitivity for all vegetation. We tested whether variable drought sensitivities are needed to explain the observed large-scale patterns of drought impact on the carbon, water and energy fluxes. We implemented data-driven drought sensitivities in the Community Atmosphere Biosphere Land Exchange (CABLE) LSMmore » and evaluated alternative sensitivities across a latitudinal gradient in Europe during the 2003 heatwave. The model predicted an overly abrupt onset of drought unless average soil water potential was calculated with dynamic weighting across soil layers. We found that high drought sensitivity at the most mesic sites, and low drought sensitivity at the most xeric sites, was necessary to accurately model responses during drought. Furthermore, our results indicate that LSMs will over-estimate drought impacts in drier climates unless different sensitivity of vegetation to drought is taken into account.« less
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Moschen, Sebastián; Di Rienzo, Julio A; Higgins, Janet; Tohge, Takayuki; Watanabe, Mutsumi; González, Sergio; Rivarola, Máximo; García-García, Francisco; Dopazo, Joaquin; Hopp, H Esteban; Hoefgen, Rainer; Fernie, Alisdair R; Paniego, Norma; Fernández, Paula; Heinz, Ruth A
2017-07-01
By integration of transcriptional and metabolic profiles we identified pathways and hubs transcription factors regulated during drought conditions in sunflower, useful for applications in molecular and/or biotechnological breeding. Drought is one of the most important environmental stresses that effects crop productivity in many agricultural regions. Sunflower is tolerant to drought conditions but the mechanisms involved in this tolerance remain unclear at the molecular level. The aim of this study was to characterize and integrate transcriptional and metabolic pathways related to drought stress in sunflower plants, by using a system biology approach. Our results showed a delay in plant senescence with an increase in the expression level of photosynthesis related genes as well as higher levels of sugars, osmoprotectant amino acids and ionic nutrients under drought conditions. In addition, we identified transcription factors that were upregulated during drought conditions and that may act as hubs in the transcriptional network. Many of these transcription factors belong to families implicated in the drought response in model species. The integration of transcriptomic and metabolomic data in this study, together with physiological measurements, has improved our understanding of the biological responses during droughts and contributes to elucidate the molecular mechanisms involved under this environmental condition. These findings will provide useful biotechnological tools to improve stress tolerance while maintaining crop yield under restricted water availability.
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SlCOR413IM1: A novel cold-regulation gene from tomato, enhances drought stress tolerance in tobacco.
Ma, Xiaocui; Wang, Guodong; Zhao, Weiyang; Yang, Minmin; Ma, Nana; Kong, Fanying; Dong, Xinchun; Meng, Qingwei
2017-09-01
Drought stress adversely affects plant growth, development, and productivity. Genes functioning in plant response to drought stress are essential for drought tolerance. In this study, SlCOR413IM1, a cold-regulated gene isolated from Solanum lycopersium, was transferred to Nicotiana tabacum to investigate its function under drought stress. The subcellular localisation of SlCOR413IM1-GFP fusion protein in Arabidopsis protoplasts suggested that SlCOR413IM1 is a chloroplast protein. Expression analyses revealed that SlCOR413IM1 responded to drought and cold stresses. Under drought stress, transgenic plants maintained the high maximum photochemical efficiency, net photosynthetic rate (Pn) and D1 protein content of photosystem II (PSII). Compared with wild-type (WT) plants, transgenic plants showed higher superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities and proline and soluble sugar content, which reduced reactive oxygen species (ROS) generation. However, the high SOD and APX activities in transgenic plants were independent of their transcription levels. Moreover, the transgenic plants exhibited better seed germination, water status and survival, as well as lower malondialdehyde (MDA) content and relative electrical conductivity (REC) than WT plants under drought stress. Taken together, these data demonstrated that overexpression of SlCOR413IM1 enhanced drought stress tolerance in transgenic tobacco. Copyright © 2017. Published by Elsevier GmbH.
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Ren, Yongbing; Miao, Min; Meng, Yun; Cao, Jiasheng; Fan, Tingting; Yue, Junyang; Xiao, Fangming; Liu, Yongsheng; Cao, Shuqing
2018-06-26
Proline accumulation is one of the most important adaptation mechanisms for plants to cope with environmental stresses, such as drought and freezing. However, the molecular mechanism of proline homeostasis under these stresses is largely unknown. Here, we identified a mitochondrial protein, DFR1, involved in the inhibition of proline degradation in Arabidopsis. DFR1 was strongly induced by drought and cold stresses. The dfr1 knockdown mutants showed hypersensitivity to drought and freezing stresses, whereas the DFR1 overexpression plants exhibited enhanced tolerance, which was positively correlated with proline levels. DFR1 interacts with proline degradation enzymes PDH1/2 and P5CDH and compromises their activities. Genetic analysis showed that DFR1 acts upstream of PDH1/2 and P5CDH to positively regulate proline accumulation. Our results demonstrate a regulatory mechanism by which, under drought and freezing stresses, DFR1 interacts with PDH1/2 and P5CDH to abrogate their activities to maintain proline homeostasis, thereby conferring drought and freezing tolerance. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.
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Genome wide association study (GWAS) for grain yield in rice cultivated under water deficit.
Pantalião, Gabriel Feresin; Narciso, Marcelo; Guimarães, Cléber; Castro, Adriano; Colombari, José Manoel; Breseghello, Flavio; Rodrigues, Luana; Vianello, Rosana Pereira; Borba, Tereza Oliveira; Brondani, Claudio
2016-12-01
The identification of rice drought tolerant materials is crucial for the development of best performing cultivars for the upland cultivation system. This study aimed to identify markers and candidate genes associated with drought tolerance by Genome Wide Association Study analysis, in order to develop tools for use in rice breeding programs. This analysis was made with 175 upland rice accessions (Oryza sativa), evaluated in experiments with and without water restriction, and 150,325 SNPs. Thirteen SNP markers associated with yield under drought conditions were identified. Through stepwise regression analysis, eight SNP markers were selected and validated in silico, and when tested by PCR, two out of the eight SNP markers were able to identify a group of rice genotypes with higher productivity under drought. These results are encouraging for deriving markers for the routine analysis of marker assisted selection. From the drought experiment, including the genes inherited in linkage blocks, 50 genes were identified, from which 30 were annotated, and 10 were previously related to drought and/or abiotic stress tolerance, such as the transcription factors WRKY and Apetala2, and protein kinases.
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NASA Astrophysics Data System (ADS)
Bateman, Amber; Lewandrowski, Wolfgang; Stevens, Jason; Muñoz-Rojas, Miriam
2016-04-01
Introduction With the limited knowledge available regarding the impact of drought on seedling growth, an understanding of seedling tolerance to arid conditions is crucial for restoration success (James et al., 2013; Muñoz-Rojas et al., 2014). However, restoration in semi-arid areas faces the challenge of re-establishing plant communities on altered soil substrates (Muñoz-Rojas et al., 2015). These substrates are a result of anthropogenic disturbances such as mining which have altered the plant-soil-water dynamics of the ecosystem (Machado et al., 2013). The aim of this study was to assess the impact of mining on the plant-soil-water dynamics of an arid ecosystem of Western Australia (Pilbara region, North Western Australia) and the implications these altered relationships have on seedling growth and their responses to drought. Methods Drought responses of native plant species were assessed through a series of glasshouse experiments. Firstly, 21 species dominant to the Pilbara region were subjected to drought in a topsoil growth media to assess variation in responses (leaf water potential at the time of stomatal closure) across species and identify traits associated with drought tolerance. Secondly, four species ranging in their drought tolerance identified previously, were grown to two leaf stages (second and fourth leaf stage) in three mining substrates (topsoil, a topsoil and waste mix and waste) to assess seedling drought responses to various potential restoration substrates and how that varied with plant development stage. Results and discussion Four morphological traits were found to be significantly associated with drought indicators (leaf mass ratio, stem area, stem length, stem weight), however, these were weak correlations. Waste substrate and its addition to topsoil reduced plant total biomass but did not alter species responses to drought. However, the soil physical properties of the waste reduced water retention and water availability for plant uptake resulting in seedling mortality at less negative soil water potential. Finally, no significant differences in drought tolerance were observed between the two leaf stages across the four species tested. Analysis of plant desiccation curves found the advanced leaf stage to be less tolerant of drought as shown by a decrease in soil water potential at the time of stomatal closure. Species possess a range of morphological traits, some of which are associated with drought tolerance. However, these traits on their own may not be main drivers for drought resilience and other factors play a role, for example soil nutrient availability. Materials tested in this study that may be available to create novel restoration substrates hinder plant growth but not necessarily plant responses to drought. These findings go a long way to defining some of the limitations of seedling growth and the degree of drought tolerance which will assist in the management of post-mining restoration. References James, J.J., Sheley, R.L., Erickson,T., Rollins, K.S., Taylor, M.H., Dixon, K.W. (2013) A systems approach to restoring degraded drylands. Journal of Applied Ecology 50:730-739. Machado, N. A. M., Leite, M. G. P., Figueiredo, M. A., Kozovits, A. R. (2013) Growing Ereman-thus erythropappus in crushed laterite: A promising alternative to topsoil for baux¬ite-mine revegetation. Journal of Environmental Management 129: 149-156. Muñoz-Rojas, M., Erickson, T., Merritt, D., Dixon, K. (2014) Optimising post-mining soil conditions to maximise restoration success in a biodiverse semiarid environment. Geophysical Research. Abstracts Vol. 16, EGU2014-2069-1, EGU General Assembly. Muñoz-Rojas, M., Erickson, T., Merritt, D., Dixon, K. (2015) Applying soil science for restoration of post mining degraded landscapes in semi-arid Australia: challenges and opportunities. Geophysical Research. Abstracts Vol. 17, EGU2015-3967-1, EGU General Assembly.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Childs, Kevin; Buell, Robin; Zhao, Bingyu
Switchgrass (Panicum virgatum) is a warm-season C4 grass that is a target lignocellulosic biofuel species for use in the United States due to its local adaption capabilities and high biomass accumulation. Two ecotypes of switchgrass have been described. Members of the lowland ecotype are taller, have narrower leaf blades and generate more biomass compared to individuals from the upland ecotype. Additionally, lowland plants are generally found in the southern United States while upland switchgrass is more typically present in the northern United States. These differences are important as it is envisioned that switchgrass for biofuel production will typically be grownmore » on marginal lands in the northern United States to supplement and diversify farmers' traditional crop incomes. While lowland switchgrass is more productive, it has poor winter survivability in northern latitudes where upland switchgrass is expected to be grown for biofuel use. Abiotic stresses likely to be encountered by switchgrass include drought and salinity. Despite initially being described as preferring wetter environments, members of the lowland ecotype have been characterized as being more drought tolerant than plants of the upland ecotype. Nonetheless, direct trials have indicated that variation for drought tolerance exists in both ecotypes, but prior to this project, only a relatively small number of switchgrass lines had been tested for drought responses. Similarly, switchgrass cultivars have not been widely tested for salt tolerance, but a few studies have shown that even mild salt stress can inhibit growth. The effects of drought and salt stress on plant growth are complex. Both drought and salinity affect the osmotic potential of plant cells and negatively affect plant growth due to reduced water potential and reduced photosynthesis that results from lower stomatal conductance of CO 2. Plants respond to drought and salt stress by activating genes that directly attempt to reduce the stress (e.g., transmembrane pumps that partition Na +) and mitigate the effects of the stress (e.g., synthesis of osmoprotectant metabolites and stress-related signaling compounds). Prior to the start of this project, no gene expression analysis had been performed on switchgrass under conditions of drought or salt stress, and therefore, relevant gene networks responding to drought and salt stress were unknown in switchgrass. In this project, we performed drought, salt and alkali-salt screens on 49 switchgrass cultivars (Liu et al 2014; Liu et al 2015; Hu et al 2015; Kim et al 2016). These experiments demonstrated that a wide range of variation exists within switchgrass for drought, salt and alkali-salt tolerance and that, while the lowland ecotype of switchgrass is often considered more tolerant of abiotic stresses, there are some upland switchgrass lines that are also very tolerant of drought, salt and alkali-salt stress. We also conducted drought and salt time course experiments with Alamo and Dacotah. We have identified modules of coexpressed genes that differentiate Alamo and Dacotah drought responses. We are continuing to analyze these results and plan to submit manuscripts describing this work in early 2017. In an effort to show how drought- and salt-related gene modules could be dissected, we generated transgenic switchgrass overexpressing either PvGTγ-1 or ZmDREB2. Increased expression of PvGTγ-1 does confer increased salt tolerance, and we were able to identify genes that are induced and suppressed by PvGTγ-1. Overexpression of ZmDREB2 increases drought tolerance in switchgrass. Analysis of the PvGTγ-1 and ZmDREB2 overexpression work is ongoing, and we plan to prepare manuscripts about these experiments for submission in early 2017.« less
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Transcriptional regulation of drought response: a tortuous network of transcriptional factors
Singh, Dhriti; Laxmi, Ashverya
2015-01-01
Drought is one of the leading factors responsible for the reduction in crop yield worldwide. Due to climate change, in future, more areas are going to be affected by drought and for prolonged periods. Therefore, understanding the mechanisms underlying the drought response is one of the major scientific concerns for improving crop yield. Plants deploy diverse strategies and mechanisms to respond and tolerate drought stress. Expression of numerous genes is modulated in different plants under drought stress that help them to optimize their growth and development. Plant hormone abscisic acid (ABA) plays a major role in plant response and tolerance by regulating the expression of many genes under drought stress. Transcription factors being the major regulator of gene expression play a crucial role in stress response. ABA regulates the expression of most of the target genes through ABA-responsive element (ABRE) binding protein/ABRE binding factor (AREB/ABF) transcription factors. Genes regulated by AREB/ABFs constitute a regulon termed as AREB/ABF regulon. In addition to this, drought responsive genes are also regulated by ABA-independent mechanisms. In ABA-independent regulation, dehydration-responsive element binding protein (DREB), NAM, ATAF, and CUC regulons play an important role by regulating many drought-responsive genes. Apart from these major regulons, MYB/MYC, WRKY, and nuclear factor-Y (NF-Y) transcription factors are also involved in drought response and tolerance. Our understanding about transcriptional regulation of drought is still evolving. Recent reports have suggested the existence of crosstalk between different transcription factors operating under drought stress. In this article, we have reviewed various regulons working under drought stress and their crosstalk with each other. PMID:26579147
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Stronger seasonal adjustment in leaf turgor loss point in lianas than trees in an Amazonian forest.
Maréchaux, Isabelle; Bartlett, Megan K; Iribar, Amaia; Sack, Lawren; Chave, Jérôme
2017-01-01
Pan-tropically, liana density increases with decreasing rainfall and increasing seasonality. This pattern has led to the hypothesis that lianas display a growth advantage over trees under dry conditions. However, the physiological mechanisms underpinning this hypothesis remain elusive. A key trait influencing leaf and plant drought tolerance is the leaf water potential at turgor loss point (π tlp ). π tlp adjusts under drier conditions and this contributes to improved leaf drought tolerance. For co-occurring Amazonian tree (n = 247) and liana (n = 57) individuals measured during the dry and the wet seasons, lianas showed a stronger osmotic adjustment than trees. Liana leaves were less drought-tolerant than trees in the wet season, but reached similar drought tolerances during the dry season. Stronger osmotic adjustment in lianas would contribute to turgor maintenance, a critical prerequisite for carbon uptake and growth, and to the success of lianas relative to trees in growth under drier conditions. © 2017 The Author(s).
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Over-Expression of Arabidopsis EDT1 Gene Confers Drought Tolerance in Alfalfa (Medicago sativa L.)
Zheng, Guangshun; Fan, Cunying; Di, Shaokang; Wang, Xuemin; Xiang, Chengbin; Pang, Yongzhen
2017-01-01
Alfalfa (Medicago sativa L.) is an important legume forage crop with great economic value. However, as the growth of alfalfa is seriously affected by an inadequate supply of water, drought is probably the major abiotic environmental factor that most severely affects alfalfa production worldwide. In an effort to enhance alfalfa drought tolerance, we transformed the Arabidopsis Enhanced Drought Tolerance 1 (AtEDT1) gene into alfalfa via Agrobacterium-mediated transformation. Compared with wild type plants, drought stress treatment resulted in higher survival rates and biomass, but reduced water loss rates in the transgenic plants. Furthermore, transgenic alfalfa plants had increased stomatal size, but reduced stomatal density, and these stomatal changes contributed greatly to reduced water loss from leaves. Importantly, transgenic alfalfa plants exhibited larger root systems with larger root lengths, root weight, and root diameters than wild type plants. The transgenic alfalfa plants had reduced membrane permeability and malondialdehyde content, but higher soluble sugar and proline content, higher superoxide dismutase activity, higher chlorophyll content, enhanced expression of drought-responsive genes, as compared with wild type plants. Notably, transgenic alfalfa plants grew better in a 2-year field trial and showed enhanced growth performance with increased biomass yield. All of our morphological, physiological, and molecular analyses demonstrated that the ectopic expression of AtEDT1 improved growth and enhanced drought tolerance in alfalfa. Our study provides alfalfa germplasm for use in forage improvement programs, and may help to increase alfalfa production in arid lands. PMID:29326737
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Over-Expression of Arabidopsis EDT1 Gene Confers Drought Tolerance in Alfalfa (Medicago sativa L.).
Zheng, Guangshun; Fan, Cunying; Di, Shaokang; Wang, Xuemin; Xiang, Chengbin; Pang, Yongzhen
2017-01-01
Alfalfa ( Medicago sativa L.) is an important legume forage crop with great economic value. However, as the growth of alfalfa is seriously affected by an inadequate supply of water, drought is probably the major abiotic environmental factor that most severely affects alfalfa production worldwide. In an effort to enhance alfalfa drought tolerance, we transformed the Arabidopsis Enhanced Drought Tolerance 1 ( AtEDT1 ) gene into alfalfa via Agrobacterium -mediated transformation. Compared with wild type plants, drought stress treatment resulted in higher survival rates and biomass, but reduced water loss rates in the transgenic plants. Furthermore, transgenic alfalfa plants had increased stomatal size, but reduced stomatal density, and these stomatal changes contributed greatly to reduced water loss from leaves. Importantly, transgenic alfalfa plants exhibited larger root systems with larger root lengths, root weight, and root diameters than wild type plants. The transgenic alfalfa plants had reduced membrane permeability and malondialdehyde content, but higher soluble sugar and proline content, higher superoxide dismutase activity, higher chlorophyll content, enhanced expression of drought-responsive genes, as compared with wild type plants. Notably, transgenic alfalfa plants grew better in a 2-year field trial and showed enhanced growth performance with increased biomass yield. All of our morphological, physiological, and molecular analyses demonstrated that the ectopic expression of AtEDT1 improved growth and enhanced drought tolerance in alfalfa. Our study provides alfalfa germplasm for use in forage improvement programs, and may help to increase alfalfa production in arid lands.
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The role of the F-box gene TaFBA1 from wheat (Triticum aestivum L.) in drought tolerance.
Zhou, Shumei; Sun, Xiudong; Yin, Suhong; Kong, Xiangzhu; Zhou, Shan; Xu, Ying; Luo, Yin; Wang, Wei
2014-11-01
Drought is one of the most important factors limiting plant growth and development. We identified a gene in wheat (Triticum aestivum L.) under drought stress named TaFBA1. TaFBA1 encodes a putative 325-amino-acid F-box protein with a conserved N-terminal F-box domain and a C-terminal AMN1 domain. Real-time RT-PCR analysis revealed that TaFBA1 transcript accumulation was upregulated by high-salinity, water stress, and abscisic acid (ABA) treatment. To evaluate the functions of TaFBA1 in the regulation of drought stress responses, we produced transgenic tobacco lines overexpressing TaFBA1. Under water stress conditions, the transgenic tobacco plants had a higher germination rate, higher relative water content, net photosynthesis rate (Pn), less chlorophyll loss, and less growth inhibition than WT. These results demonstrate the high tolerance of the transgenic plants to drought stress compared to the WT. The enhanced oxidative stress tolerance of these plants, which may be involved in their drought tolerance, was indicated by their lower levels of reactive oxygen species (ROS) accumulation, MDA content, and cell membrane damage under drought stress compared to WT. The antioxidant enzyme activities were higher in the transgenic plants than in WT, which may be related to the upregulated expression of some antioxidant genes via overexpression of TaFBA1. Copyright © 2014 Elsevier Masson SAS. All rights reserved.
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Li, Yajun; Zhang, Jiachang; Zhang, Juan; Hao, Ling; Hua, Jinping; Duan, Liusheng; Zhang, Mingcai; Li, Zhaohu
2013-08-01
LOS5/ABA3 gene encoding molybdenum cofactor sulphurase is involved in aldehyde oxidase (AO) activity in Arabidopsis, which indirectly regulates ABA biosynthesis and increased stress tolerance. Here, we used a constitutive super promoter to drive LOS5/ABA3 overexpression in soybean (Glycine max L.) to enhance drought tolerance in growth chamber and field conditions. Expression of LOS5/ABA3 was up-regulated by drought stress, which led to increasing AO activity and then a notable increase in ABA accumulation. Transgenic soybean under drought stress had reduced water loss by decreased stomatal aperture size and transpiration rate, which alleviated leaf wilting and maintained higher relative water content. Exposed to drought stress, transgenic soybean exhibited reduced cell membrane damage by reducing electrolyte leakage and production of malondialdehyde and promoting proline accumulation and antioxidant enzyme activities. Also, overexpression of LOS5/ABA3 enhanced expression of stress-up-regulated genes. Furthermore, the seed yield of transgenic plants is at least 21% higher than that of wide-type plants under drought stress conditions in the field. These data suggest that overexpression of LOS5/ABA3 could improve drought tolerance in transgenic soybean via enhanced ABA accumulation, which could activate expression of stress-up-regulated genes and cause a series of physiological and biochemical resistant responses. © 2013 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.
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Yoshimura, Kazuya; Masuda, Akiko; Kuwano, Masayoshi; Yokota, Akiho; Akashi, Kinya
2008-02-01
Water availability is a critical determinant for the growth and ecological distribution of terrestrial plants. Although some xerophytes are unique regarding their highly developed root architecture and the successful adaptation to arid environments, virtually nothing is known about the molecular mechanisms underlying this adaptation. Here, we report physiological and molecular responses of wild watermelon (Citrullus lanatus sp.), which exhibits extraordinarily high drought resistance. At the early stage of drought stress, root development of wild watermelon was significantly enhanced compared with that of the irrigated plants, indicating the activation of a drought avoidance mechanism for absorbing water from deep soil layers. Consistent with this observation, comparative proteome analysis revealed that many proteins induced in the early stage of drought stress are involved in root morphogenesis and carbon/nitrogen metabolism, which may contribute to the drought avoidance via the enhancement of root growth. On the other hand, lignin synthesis-related proteins and molecular chaperones, which may function in the enhancement of physical desiccation tolerance and maintenance of protein integrity, respectively, were induced mostly at the later stage of drought stress. Our findings suggest that this xerophyte switches survival strategies from drought avoidance to drought tolerance during the progression of drought stress, by regulating its root proteome in a temporally programmed manner. This study provides new insights into the complex molecular networks within plant roots involved in the adaptation to adverse environments.
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Salehi, Mohammadreza; Salehi, Hassan; xNiazi, Hassan; Ghobadi, Cyrus
2014-03-01
The aim of this study is to find Iranian tall fescue accessions that tolerate drought stress and investigation on phylogenetical, morphological, and physiological characterization of them. For this propose, inter-simple sequence repeats (ISSR) markers were used to examine the genetic variability of accessions from different provinces of Iran. Of 21 primers, 20 primers generated highly reproducible fragments. Using these primers, 390 discernible DNA fragments were produced with 367 (93.95 %) being polymorphic. The polymorphic information content (PIC) values ranged from 0.948 to 0.976, with a mean PIC value of 0.969. Probability identity (PI) and discriminating power (D = 1-PI) among the primers ranged from 0.001 to 0.004 and 0.998 to 0.995, respectively. A binary qualitative data matrix was constructed. Data analyses were performed using the NTSYS software and the similarity values were used to generate a dendrogram via UPGMA. To study the drought stress, plants were irrigated at 25 % FC condition for three times. Fresh leaves were collected to measure physiological characters including: superoxide dismutase, catalase, and peroxidase activities and proline and total chlorophyll content at two times, before and after stress application. Relative water content, fresh and dry weight ratio, survival percentage, and visual quality were evaluated after stress. Morphological and physiological characters were assessed in order to classify accessions as either tolerant or sensitive using Ward's method of Hierarchical cluster analysis in SPSS software. The results of present study demonstrated that the ISSR markers are useful for studying tall fescue genetic diversity. Convergence of morphological and physiological characterizations during drought stress and phylogenetic relationship results showed that accessions can be grouped into four clusters; drought-tolerant accessions that collected from west of Iran, drought-tolerant accessions collected from northwest of Iran, drought semi-tolerant accessions collected from center of Iran, and drought-sensitive accessions collected from north of Iran. Data presented could be used to classify the tall fescue accessions based on suitability of cultivation in the regions studied or the regions with the similar environmental condition.
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Lipid transfer protein 3 as a target of MYB96 mediates freezing and drought stress in Arabidopsis
Yang, Shuhua
2013-01-01
Several lipid-transfer proteins were reported to modulate the plant response to biotic stress; however, whether lipid-transfer proteins are also involved in abiotic stress remains unknown. This study characterized the function of a lipid-transfer protein, LTP3, during freezing and drought stress. LTP3 was expressed ubiquitously and the LTP3 protein was localized to the cytoplasm. A biochemical study showed that LTP3 was able to bind to lipids. Overexpression of LTP3 resulted in constitutively enhanced freezing tolerance without affecting the expression of CBFs and their target COR genes. Further analyses showed that LTP3 was positively regulated by MYB96 via the direct binding to the LTP3 promoter; consistently, transgenic plants overexpressing MYB96 exhibited enhanced freezing tolerance. This study also found that the loss-of-function mutant ltp3 was sensitive to drought stress, whereas overexpressing plants were drought tolerant, phenotypes reminiscent of myb96 mutant plants and MYB96-overexpressing plants. Taken together, these results demonstrate that LTP3 acts as a target of MYB96 to be involved in plant tolerance to freezing and drought stress. PMID:23404903
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Changes in tree functional composition amplify the response of forest biomass to climate variability
NASA Astrophysics Data System (ADS)
Lichstein, Jeremy; Zhang, Tao; Niinemets, Ulo; Sheffield, Justin
2017-04-01
The response of forest carbon storage to climate change is highly uncertain, contributing substantially to the divergence among global climate model projections. Numerous studies have documented responses of forest ecosystems to climate change and variability, including drought-induced increases in tree mortality rates. However, the sensitivity of forests to climate variability - in terms of both biomass carbon storage and functional components of tree species composition - has yet to be quantified across a large region using systematically sampled data. Here, we combine systematic forest inventories across the eastern USA with a species-level drought-tolerance index, derived from a meta-analysis of published literature, to quantify changes in forest biomass and community-mean-drought-tolerance in one-degree grid cells from the 1980s to 2000s. We show that forest biomass responds to decadal-scale changes in water deficit and that this biomass response is amplified by concurrent changes in community-mean-drought-tolerance. The amplification of the direct effects of water stress on biomass occurs because water stress tends to induce a shift in tree species composition towards more drought-tolerant but lower-biomass species. Multiple plant functional traits are correlated with the above species-level drought-tolerance index, and likely contribute to the decrease in biomass with increasing drought-tolerance. These traits include wood density and P50 (the xylem water potential at which a plant loses 50% of its hydraulic conductivity). Simulations with a trait- and competition-based dynamic global vegetation model suggest that species differences in plant carbon allocation to wood, leaves, and fine roots also likely contribute to the observed decrease in biomass with increasing drought-tolerance, because competition drives plants to over-invest in fine roots when water is limiting. Thus, the most competitive species under dry conditions have greater root allocation but lower total biomass than productivity-maximizing plants. Amplification of the biomass-climate response due to shifts in species functional composition (temporal beta diversity) contrasts with evidence that local (alpha) diversity increases ecosystem stability, including increased resistance to climate extremes. These contrasting effects of alpha and beta diversity highlight the need to better understand how different components of biodiversity, including changes in the functional traits of the dominant plant species, affect ecosystem functioning.
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Ha, Chien Van; Watanabe, Yasuko; Tran, Uyen Thi; Le, Dung Tien; Tanaka, Maho; Nguyen, Kien Huu; Seki, Motoaki; Nguyen, Dong Van; Tran, Lam-Son Phan
2015-01-01
The economically important DT2008 and the model Williams 82 (W82) soybean cultivars were reported to have differential drought-tolerant degree to dehydration and drought, which was associated with root trait. Here, we used 66K Affymetrix Soybean Array GeneChip to compare the root transcriptomes of DT2008 and W82 seedlings under normal, as well as mild (2 h treatment) and severe (10 h treatment) dehydration conditions. Out of the 38172 soybean genes annotated with high confidence, 822 (2.15%) and 632 (1.66%) genes showed altered expression by dehydration in W82 and DT2008 roots, respectively, suggesting that a larger machinery is required to be activated in the drought-sensitive W82 cultivar to cope with the stress. We also observed that long-term dehydration period induced expression change of more genes in soybean roots than the short-term one, independently of the genotypes. Furthermore, our data suggest that the higher drought tolerability of DT2008 might be attributed to the higher number of genes induced in DT2008 roots than in W82 roots by early dehydration, and to the expression changes of more genes triggered by short-term dehydration than those by prolonged dehydration in DT2008 roots vs. W82 roots. Differentially expressed genes (DEGs) that could be predicted to have a known function were further analyzed to gain a basic understanding on how soybean plants respond to dehydration for their survival. The higher drought tolerability of DT2008 vs. W82 might be attributed to differential expression in genes encoding osmoprotectant biosynthesis-, detoxification- or cell wall-related proteins, kinases, transcription factors and phosphatase 2C proteins. This research allowed us to identify genetic components that contribute to the improved drought tolerance of DT2008, as well as provide a useful genetic resource for in-depth functional analyses that ultimately leads to development of soybean cultivars with improved tolerance to drought. PMID:26300889
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Vargas, Lívia; Santa Brígida, Ailton B; Mota Filho, José P; de Carvalho, Thais G; Rojas, Cristian A; Vaneechoutte, Dries; Van Bel, Michiel; Farrinelli, Laurent; Ferreira, Paulo C G; Vandepoele, Klaas; Hemerly, Adriana S
2014-01-01
Sugarcane interacts with particular types of beneficial nitrogen-fixing bacteria that provide fixed-nitrogen and plant growth hormones to host plants, promoting an increase in plant biomass. Other benefits, as enhanced tolerance to abiotic stresses have been reported to some diazotrophs. Here we aim to study the effects of the association between the diazotroph Gluconacetobacter diazotrophicus PAL5 and sugarcane cv. SP70-1143 during water depletion by characterizing differential transcriptome profiles of sugarcane. RNA-seq libraries were generated from roots and shoots of sugarcane plants free of endophytes that were inoculated with G. diazotrophicus and subjected to water depletion for 3 days. A sugarcane reference transcriptome was constructed and used for the identification of differentially expressed transcripts. The differential profile of non-inoculated SP70-1143 suggests that it responds to water deficit stress by the activation of drought-responsive markers and hormone pathways, as ABA and Ethylene. qRT-PCR revealed that root samples had higher levels of G. diazotrophicus 3 days after water deficit, compared to roots of inoculated plants watered normally. With prolonged drought only inoculated plants survived, indicating that SP70-1143 plants colonized with G. diazotrophicus become more tolerant to drought stress than non-inoculated plants. Strengthening this hypothesis, several gene expression responses to drought were inactivated or regulated in an opposite manner, especially in roots, when plants were colonized by the bacteria. The data suggests that colonized roots would not be suffering from stress in the same way as non-inoculated plants. On the other hand, shoots specifically activate ABA-dependent signaling genes, which could act as key elements in the drought resistance conferred by G. diazotrophicus to SP70-1143. This work reports for the first time the involvement of G. diazotrophicus in the promotion of drought-tolerance to sugarcane cv. SP70-1143, and it describes the initial molecular events that may trigger the increased drought tolerance in the host plant.
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Vargas, Lívia; Santa Brígida, Ailton B.; Mota Filho, José P.; de Carvalho, Thais G.; Rojas, Cristian A.; Vaneechoutte, Dries; Van Bel, Michiel; Farrinelli, Laurent; Ferreira, Paulo C. G.; Vandepoele, Klaas; Hemerly, Adriana S.
2014-01-01
Sugarcane interacts with particular types of beneficial nitrogen-fixing bacteria that provide fixed-nitrogen and plant growth hormones to host plants, promoting an increase in plant biomass. Other benefits, as enhanced tolerance to abiotic stresses have been reported to some diazotrophs. Here we aim to study the effects of the association between the diazotroph Gluconacetobacter diazotrophicus PAL5 and sugarcane cv. SP70-1143 during water depletion by characterizing differential transcriptome profiles of sugarcane. RNA-seq libraries were generated from roots and shoots of sugarcane plants free of endophytes that were inoculated with G. diazotrophicus and subjected to water depletion for 3 days. A sugarcane reference transcriptome was constructed and used for the identification of differentially expressed transcripts. The differential profile of non-inoculated SP70-1143 suggests that it responds to water deficit stress by the activation of drought-responsive markers and hormone pathways, as ABA and Ethylene. qRT-PCR revealed that root samples had higher levels of G. diazotrophicus 3 days after water deficit, compared to roots of inoculated plants watered normally. With prolonged drought only inoculated plants survived, indicating that SP70-1143 plants colonized with G. diazotrophicus become more tolerant to drought stress than non-inoculated plants. Strengthening this hypothesis, several gene expression responses to drought were inactivated or regulated in an opposite manner, especially in roots, when plants were colonized by the bacteria. The data suggests that colonized roots would not be suffering from stress in the same way as non-inoculated plants. On the other hand, shoots specifically activate ABA-dependent signaling genes, which could act as key elements in the drought resistance conferred by G. diazotrophicus to SP70-1143. This work reports for the first time the involvement of G. diazotrophicus in the promotion of drought-tolerance to sugarcane cv. SP70-1143, and it describes the initial molecular events that may trigger the increased drought tolerance in the host plant. PMID:25489849
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Mashilo, Jacob; Odindo, Alfred O; Shimelis, Hussein A; Musenge, Pearl; Tesfay, Samson Z; Magwaza, Lembe S
2017-11-01
Successful cultivation of bottle gourd in arid and semi-arid areas of sub-Saharan Africa and globally requires the identification of drought tolerant parents for developing superior genotypes with increased drought resistance. The objective of this study was to determine the level of drought tolerance among genetically diverse South African bottle gourd landraces based on leaf gas exchange and photosynthetic efficiency and identify promising genotypes for breeding. The responses of 12 bottle gourd landraces grown in glasshouse under non-stressed (NS) and drought-stressed (DS) conditions were studied. A significant genotype x water regime interaction was observed for gs, T, A, A/C i , IWUE, WUE ins , F m ', F v '/F m ', Ф PSII , qP, qN, ETR, ETR/A and AES indicating variability in response among the studied bottle gourd landraces under NS and DS conditions. Principal component analysis identified three principal components (PC's) under drought stress condition contributing to 82.9% of total variation among leaf gas exchange and chlorophyll fluorescence parameters measured. PC1 explained 36% of total variation contributed by gs, T, F 0 ', F m ', F v '/F m ' and qN, while PC2 explained 28% of the variation and highly correlated with A, A/C i , IWUE, WUE ins ETR/A and AES. PC3 explained 14% of total variation contributed by Ф PSII , qP and ETR. Principal biplot analysis allowed the identification of drought tolerant genotypes such as BG-27, BG-48, BG-58, BG-79, BG-70 and BG-78 which were grouped based on high gs, A, F m 'F v '/F m ', qN, ETR/A and AES under DS condition. The study suggests that the identified physiological traits could be useful indicators in the selection of bottle gourd genotypes for increased drought tolerance. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
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Understanding drought propagation in the UK in the context of climatology and catchment properties
NASA Astrophysics Data System (ADS)
Barker, Lucy; Hannaford, Jamie; Bloomfield, John; Marchant, Ben
2017-04-01
Droughts are a complex natural phenomena that are challenging to plan and prepare for. The propagation of droughts through the hydrological cycle is one of many factors which contribute to this complexity, and a thorough understanding of drought propagation is crucial for informed drought management, particularly in terms of water resources management in both the short and long term. Previous studies have found that both climatological and catchment factors cause lags in drought propagation from meteorological to hydrological and hydrogeological droughts. There are strong gradients in both climatology and catchment properties across the UK. Catchments in the north and west of the UK are relatively impermeable, upland catchments with thin soils and receive the highest annual precipitation with relatively low mean annual temperatures. Conversely, in the south and east of the UK, characterised by higher mean temperatures and lower annual precipitation, catchments are underlain by a number of major aquifers (e.g. Chalk, limestone) and are typically associated with high baseflow rivers. Here we explore the effects of these gradients in climatology and catchments on the propagation of droughts. Using standardised drought indices (the Standardised Precipitation Index; the Standardised Streamflow Index; and the Standardised Groundwater Index) we analyse drought propagation characteristics for selected catchment-borehole pairs across the UK using reconstructed time series back to the 19th century. We investigate how the timing, nature and predictability of drought propagation changes across the UK, given gradients in climatology and catchment characteristics. We use probability of detection methods, usually used for forecast verification, to investigate how well precipitation and streamflow deficits predict deficits in streamflow and groundwater levels and how this varies across the UK.
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Kudo, Madoka; Kidokoro, Satoshi; Yoshida, Takuya; Mizoi, Junya; Todaka, Daisuke; Fernie, Alisdair R; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko
2017-04-01
Although a variety of transgenic plants that are tolerant to drought stress have been generated, many of these plants show growth retardation. To improve drought tolerance and plant growth, we applied a gene-stacking approach using two transcription factor genes: DEHYDRATION-RESPONSIVE ELEMENT-BINDING 1A (DREB1A) and rice PHYTOCHROME-INTERACTING FACTOR-LIKE 1 (OsPIL1). The overexpression of DREB1A has been reported to improve drought stress tolerance in various crops, although it also causes a severe dwarf phenotype. OsPIL1 is a rice homologue of Arabidopsis PHYTOCHROME-INTERACTING FACTOR 4 (PIF4), and it enhances cell elongation by activating cell wall-related gene expression. We found that the OsPIL1 protein was more stable than PIF4 under light conditions in Arabidopsis protoplasts. Transactivation analyses revealed that DREB1A and OsPIL1 did not negatively affect each other's transcriptional activities. The transgenic plants overexpressing both OsPIL1 and DREB1A showed the improved drought stress tolerance similar to that of DREB1A overexpressors. Furthermore, double overexpressors showed the enhanced hypocotyl elongation and floral induction compared with the DREB1A overexpressors. Metabolome analyses indicated that compatible solutes, such as sugars and amino acids, accumulated in the double overexpressors, which was similar to the observations of the DREB1A overexpressors. Transcriptome analyses showed an increased expression of abiotic stress-inducible DREB1A downstream genes and cell elongation-related OsPIL1 downstream genes in the double overexpressors, which suggests that these two transcription factors function independently in the transgenic plants despite the trade-offs required to balance plant growth and stress tolerance. Our study provides a basis for plant genetic engineering designed to overcome growth retardation in drought-tolerant transgenic plants. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.
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Shukla, Nandani; Awasthi, R P; Rawat, Laxmi; Kumar, J
2012-05-01
Rice is one of the most important food crops drastically affected by drought in lowland rice ecosystems. In the present study, the impact of drought tolerant isolates of endophytic fungus Trichoderma harzianum on rice response to drought was investigated. Out of 43 Trichoderma isolates studied, only five isolates viz., Th 56, Th 69, Th 75, Th 82 and Th 89 were selected to be drought tolerant as these were able to colonize well on cow dung at low moisture content of 10-20 percent, though two isolates, Th 56 and Th 75, grew even at 5 percent moisture content. Trichoderma-colonized rice seedlings were slower to wilt in response to drought. Colonization delayed drought induced changes like stomatal conductance, net photosynthesis and leaf greenness. Drought conditions varying from 3 to 9 days of withholding water led to an increase in the concentration of many stress induced metabolites in rice leaves and decrease of MSI, while Trichoderma colonization caused a decrease in proline, MDA and H₂O₂ contents, and increase in phenolics concentration and MSI. Among test isolates, Th 56 induced maximum drought tolerance as treated plants recorded only 20-40 percent wilting even at 9 DDS. With or without exposure to drought, colonization by Trichoderma promoted seedling growth, with Th 56 giving the most consistent effect. The primary direct effect of Trichoderma colonization was promotion of root growth, regardless of water status, which caused delay in the drought responses of rice plants. Copyright © 2012 Elsevier Masson SAS. All rights reserved.
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Yong, Bin; Xie, Huan; Li, Zhou; Li, Ya-Ping; Zhang, Yan; Nie, Gang; Zhang, Xin-Quan; Ma, Xiao; Huang, Lin-Kai; Yan, Yan-Hong; Peng, Yan
2017-01-01
In order to investigate the physiological effects of exogenous γ-aminobutyric acid (GABA) on drought tolerance in white clover (Trifolium repens), GABA shunt, polyamines (PAs), and proline (Pro) metabolism were examined after plants pretreated with or without GABA (8 mM) and then exposed to water or 15% PEG-induced drought stress in growth chamber. In this study, exogenous application of GABA effectively alleviated drought-induced damage in leaves, as reflected by significantly higher relative water content, lower electrolyte leakage, lipid peroxidation, and leaf wilt. Exogenous GABA further promoted drought-induced increases in GABA transaminase and alpha ketone glutarate dehydrogenase activities, but inhibited glutamate decarboxylase activity under both control and drought conditions, resulting in an increase in endogenous glutamate (Glu) and GABA content. Besides, exogenous GABA could well accelerated PAs synthesis and suppressed PAs catabolism, which lead to the extremely enhanced different types of PAs content (free Put and Spd, insoluble bound Spd and Spm, soluble conjugated Spd and Spm, and total Put, Spd and Spm) under drought stress. In addition, exogenous GABA application further activated drought-induced Δ 1 -pyrroline-5-carboxylate synthetase and proline dehydrogenase activities, but suppressed drought-facilitated ornithine -δ-amino transferase activities, leading to a higher Pro accumulation and metabolism in GABA-pretreated plants in the middle and last period of drought. The results suggested that increased endogenous GABA by exogenous GABA treatment could improve drought tolerance of white clover associated with a positive regulation in the GABA-shunt, PAs and Pro metabolism.
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Yong, Bin; Xie, Huan; Li, Zhou; Li, Ya-Ping; Zhang, Yan; Nie, Gang; Zhang, Xin-Quan; Ma, Xiao; Huang, Lin-Kai; Yan, Yan-Hong; Peng, Yan
2017-01-01
In order to investigate the physiological effects of exogenous γ-aminobutyric acid (GABA) on drought tolerance in white clover (Trifolium repens), GABA shunt, polyamines (PAs), and proline (Pro) metabolism were examined after plants pretreated with or without GABA (8 mM) and then exposed to water or 15% PEG-induced drought stress in growth chamber. In this study, exogenous application of GABA effectively alleviated drought-induced damage in leaves, as reflected by significantly higher relative water content, lower electrolyte leakage, lipid peroxidation, and leaf wilt. Exogenous GABA further promoted drought-induced increases in GABA transaminase and alpha ketone glutarate dehydrogenase activities, but inhibited glutamate decarboxylase activity under both control and drought conditions, resulting in an increase in endogenous glutamate (Glu) and GABA content. Besides, exogenous GABA could well accelerated PAs synthesis and suppressed PAs catabolism, which lead to the extremely enhanced different types of PAs content (free Put and Spd, insoluble bound Spd and Spm, soluble conjugated Spd and Spm, and total Put, Spd and Spm) under drought stress. In addition, exogenous GABA application further activated drought-induced Δ1-pyrroline-5-carboxylate synthetase and proline dehydrogenase activities, but suppressed drought-facilitated ornithine -δ-amino transferase activities, leading to a higher Pro accumulation and metabolism in GABA-pretreated plants in the middle and last period of drought. The results suggested that increased endogenous GABA by exogenous GABA treatment could improve drought tolerance of white clover associated with a positive regulation in the GABA-shunt, PAs and Pro metabolism. PMID:29312009
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Selection System for the Stay-Green Drought Tolerance Trait in Sorghum Germplasm
USDA-ARS?s Scientific Manuscript database
Post-flowering drought tolerance is an essential trait for increasing the production of sorghum [Sorghum bicolor (L.) Moench] and other cereals in Mediterranean and semiarid tropical climates. Current methodologies for identifying the nonsenescent (stay-green) trait require the right intensity of dr...
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Habitat-specific AMF symbioses enhance drought tolerance of a native Kenyan grass
NASA Astrophysics Data System (ADS)
Petipas, Renee H.; González, Jonathan B.; Palmer, Todd M.; Brody, Alison K.
2017-01-01
The role of arbuscular mycorrhizal fungi (AMF) in enhancing plant tolerance to drought is well known. However, the degree to which AMF-plant symbioses are locally adapted has been suggested but is less well understood, especially at small spatial scales. Here, we examined the effects of two arbuscular mycorrhizal fungal communities on drought tolerance of Themeda triandra, a native African perennial bunchgrass. In our study area, mound building activities of Odontotermes sp. termites produce heterogeneous habitat, particularly with respect to water availability, and do so over small spatial scales (<50 m). Thus, plants and their AMF symbionts may experience identical climatic conditions but very different edaphic conditions. We hypothesized that AMF from off-mound areas, where plants experience drought more intensely than on termite mounds, would confer greater protection from drought conditions than AMF from termite mound soils. To test this, we conducted a greenhouse experiment in which we grew plants in soils that we inoculated with fungi from on or off termite mounds, or with a sterilized control inoculum. Our results reveal habitat-specific AMF effects on host stomatal functioning and growth. Contrary to our expectations, drought stressed grasses inoculated with AMF from termite mounds closed stomata less, and produced 60% more leaves than those inoculated with off-mound AMF, thus exhibiting higher levels of tolerance. Mound-inoculated plants that were drought stressed also produced more than twice as many leaves as non-inoculated plants. Longer-term productivity measurements indicate both on- and off-mound inoculated plants were able to recover to a greater extent than non-inoculated plants, indicating that AMF associations in general help plants recover from drought. These findings highlight the important role that AMF play in mitigating drought stress and indicate that AMF affect how plants experience drought in a small scale, habitat-specific manner.
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Bhardwaj, Jyoti; Mahajan, Monika; Yadav, Sudesh Kumar
2013-08-01
DNA methylation is known as an epigenetic modification that affects gene expression in plants. Variation in CpG methylation behavior was studied in two natural horse gram (Macrotyloma uniflorum [Lam.] Verdc.) genotypes, HPKC2 (drought-sensitive) and HPK4 (drought-tolerant). The methylation pattern in both genotypes was studied through methylation-sensitive amplified polymorphism. The results revealed that methylation was higher in HPKC2 (10.1%) than in HPK4 (8.6%). Sequencing demonstrated sequence homology with the DRE binding factor (cbf1), the POZ/BTB protein, and the Ty1-copia retrotransposon among some of the polymorphic fragments showing alteration in methylation behavior. Differences in DNA methylation patterns could explain the differential drought tolerance and the epigenetic signature of these two horse gram genotypes.
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Hu, Ling; Xie, Yan; Fan, Shoujin; Wang, Zongshuai; Wang, Fahong; Zhang, Bin; Li, Haosheng; Song, Jie; Kong, Lingan
2018-07-01
Water deficit is one of the major factors limiting crop productivity worldwide. Plant roots play a key role in uptaking water, perceiving and transducing of water deficit signals to shoot. Although the mechanisms of drought-tolerance have been reported recently, the transcriptional regulatory network of wheat root response to water stress has not been fully understood. In this study, drought-tolerant cultivar JM-262 and susceptible cultivar LM-2 are planted to characterize the root transcriptional changes and physiological responses to water deficit. A total of 8197 drought tolerance-associated differentially expressed genes (DEGs) are identified, these genes are mainly mapped to carbon metabolism, flavonoid biosynthesis, and phytohormone signal transduction. The number and expression level of DEGs involved in antioxidative and antiosmotic stresses are more enhanced in JM-262 under water stress. Furthermore, we find the DEGs related to root development are much more induced in JM-262 in phytohormone signal transduction and carbon metabolism pathway. In conclusion, JM-262 may alleviate the damage of drought by producing more osmoprotectants, ROS scavengers, biomass and energy. Interestingly, hormone signaling and cross-talk probably play an important role in promoting JM-262 greater root systems to take up more water, higher capabilities to induce more drought-related DEGs and higher resisitance to oxidative stresse. Copyright © 2018 Elsevier B.V. All rights reserved.
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Kumar, Arvind; Dixit, Shalabh; Ram, T.; Yadaw, R. B.; Mishra, K. K.; Mandal, N. P.
2014-01-01
The increased occurrence and severity of drought stress have led to a high yield decline in rice in recent years in drought-affected areas. Drought research at the International Rice Research Institute (IRRI) over the past decade has concentrated on direct selection for grain yield under drought. This approach has led to the successful development and release of 17 high-yielding drought-tolerant rice varieties in South Asia, Southeast Asia, and Africa. In addition to this, 14 quantitative trait loci (QTLs) showing a large effect against high-yielding drought-susceptible popular varieties were identified using grain yield as a selection criterion. Six of these (qDTY 1.1, qDTY 2.2, qDTY 3.1, qDTY 3.2, qDTY 6.1, and qDTY 12.1) showed an effect against two or more high-yielding genetic backgrounds in both the lowland and upland ecosystem, indicating their usefulness in increasing the grain yield of rice under drought. The yield of popular rice varieties IR64 and Vandana has been successfully improved through a well-planned marker-assisted backcross breeding approach, and QTL introgression in several other popular varieties is in progress. The identification of large-effect QTLs for grain yield under drought and the higher yield increase under drought obtained through the use of these QTLs (which has not been reported in other cereals) indicate that rice, because of its continuous cultivation in two diverse ecosystems (upland, drought tolerant, and lowland, drought susceptible), has benefited from the existence of larger genetic variability than in other cereals. This can be successfully exploited using marker-assisted breeding. PMID:25205576
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Min, Hye Jo; Jung, Ye Jin; Kang, Bin Goo; Kim, Woo Taek
2016-03-01
Abiotic stresses such as drought and low temperature critically restrict plant growth, reproduction, and productivity. Higher plants have developed various defense strategies against these unfavorable conditions. CaPUB1 (Capsicum annuum Putative U-box protein 1) is a hot pepper U-box E3 Ub ligase. Transgenic Arabidopsis plants that constitutively expressed CaPUB1 exhibited drought-sensitive phenotypes, suggesting that it functions as a negative regulator of the drought stress response. In this study, CaPUB1 was over-expressed in rice (Oryza sativa L.), and the phenotypic properties of transgenic rice plants were examined in terms of their drought and cold stress tolerance. Ubi:CaPUB1 T3 transgenic rice plants displayed phenotypes hypersensitive to dehydration, suggesting that its role in the negative regulation of drought stress response is conserved in dicot Arabidopsis and monocot rice plants. In contrast, Ubi:CaPUB1 progeny exhibited phenotypes markedly tolerant to prolonged low temperature (4°C) treatment, compared to those of wild-type plants, as determined by survival rates, electrolyte leakage, and total chlorophyll content. Cold stress-induced marker genes, including DREB1A, DREB1B, DREB1C, and Cytochrome P450, were more up-regulated by cold treatment in Ubi:CaPUB1 plants than in wild-type plants. These results suggest that CaPUB1 serves as both a negative regulator of the drought stress response and a positive regulator of the cold stress response in transgenic rice plants. This raises the possibility that CaPUB1 participates in the cross-talk between drought and low-temperature signaling pathways.
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Gimeno, Teresa E; Pías, Beatriz; Lemos-Filho, José P; Valladares, Fernando
2009-01-01
Plant populations of widely distributed species experience a broad range of environmental conditions that can be faced by phenotypic plasticity or ecotypic differentiation and local adaptation. The strategy chosen will determine a population's ability to respond to climate change. To explore this, we grew Quercus ilex (L.) seedlings from acorns collected at six selected populations from climatically contrasting localities and evaluated their response to drought and late season cold events. Maximum photosynthetic rate (A(max)), instantaneous water use efficiency (iWUE), and thermal tolerance to freeze and heat (estimated from chlorophyll fluorescence versus temperature curves) were measured in 5-month-old seedlings in control (no stress), drought (water-stressed), and cold (low suboptimal temperature) conditions. The observed responses were similar for the six populations: drought decreased A(max) and increased iWUE, and cold reduced A(max) and iWUE. All the seedlings maintained photosynthetic activity under adverse conditions (drought and cold), and rapidly increased their iWUE by closing stomata when exposed to drought. Heat and freeze tolerances were similarly high for seedlings from all the populations, and they were significantly increased by drought and cold, respectively; and were positively related to each other. Differences in seedling performance across populations were primarily induced by maternal effects mediated by seed size and to a lesser extent by idiosyncratic physiologic responses to drought and low temperatures. Tolerance to multiple stresses together with the capacity to physiologically acclimate to heat waves and cold snaps may allow Q. ilex to cope with the increasingly stressful conditions imposed by climate change. Lack of evidence of physiologic seedling adaptation to local climate may reflect opposing selection pressures to complex, multidimensional environmental conditions operating within the distribution range of this species.
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ERIC Educational Resources Information Center
Schaffer, Linda; Kingsley, Karla V.
2009-01-01
In order to demonstrate how plants remove water from the soil and release it to the atmosphere, students compared open- and closed-growing systems using drought-tolerant and higher water requirement plants. Then, students designed a drought-tolerant garden demonstrating what they had learned. Through this experience, students not only learned…
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Detection of drought tolerant genes within seedling apple rootstocks in Syria
USDA-ARS?s Scientific Manuscript database
This investigation was conducted to detect the drought tolerant genes (four genes) within seedling apple rootstocks derived from five apple genotypes, including Syrian apple cultivars. The results showed that the gene MdPepPro (a cyclophilin) was found in all studied genotypes and their progenies e...
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USDA-ARS?s Scientific Manuscript database
Jerusalem artichoke could be an alternative feedstock for bioenergy during times when there are shortages of other raw materials for the ethanol industry. However, insufficient water under rainfed conditions is a major cause of Jerusalem artichoke losses. Genetic variation for drought tolerance is...
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Molecular breeding for developing drought tolerant and disease resistant maize in sub Saharan Africa
USDA-ARS?s Scientific Manuscript database
The International Maize and Wheat Improvement Center (CIMMYT), in collaboration with public and private partners, is working on developing and disseminating drought tolerant maize for sub Saharan Africa (SSA) using pedigree selection and molecular breeding. In this paper, we provide an overview of ...
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Competition amplifies drought stress in forests across broad climatic and compositional gradients
Gleason, Kelly; Bradford, John B.; Bottero, Alessandra; D'Amato, Tony; Fraver, Shawn; Palik, Brian J.; Battaglia, Michael; Iverson, Louis R.; Kenefic, Laura; Kern, Christel C.
2017-01-01
Forests around the world are experiencing increasingly severe droughts and elevated competitive intensity due to increased tree density. However, the influence of interactions between drought and competition on forest growth remains poorly understood. Using a unique dataset of stand-scale dendrochronology sampled from 6405 trees, we quantified how annual growth of entire tree populations responds to drought and competition in eight, long-term (multi-decadal), experiments with replicated levels of density (e.g., competitive intensity) arrayed across a broad climatic and compositional gradient. Forest growth (cumulative individual tree growth within a stand) declined during drought, especially during more severe drought in drier climates. Forest growth declines were exacerbated by high density at all sites but one, particularly during periods of more severe drought. Surprisingly, the influence of forest density was persistent overall, but these density impacts were greater in the humid sites than in more arid sites. Significant density impacts occurred during periods of more extreme drought, and during warmer temperatures in the semi-arid sites but during periods of cooler temperatures in the humid sites. Because competition has a consistent influence over growth response to drought, maintaining forests at lower density may enhance resilience to drought in all climates.
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Morphological and Physiological Alteration of Maize Root Architectures on Drought Stress.
USDA-ARS?s Scientific Manuscript database
Drought tolerance is a complex agronomic trait and root characteristics logically play an important role in determining the response of plants to drought stress. Research experiments were conducted to investigate genotypic variations in morphological and physiological responses of roots to drought s...
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Proteomic profiling of γ-ECS overexpressed transgenic Nicotiana in response to drought stress.
Kumar, Deepak; Datta, Riddhi; Sinha, Ragini; Ghosh, Aparupa; Chattopadhyay, Sharmila
2014-01-01
The contribution of Glutathione (GSH) in drought stress tolerance is an established fact. However, the proteins which are directly or indirectly related to the increased level of GSH in response to drought stress are yet to be known. To explore this, here, transgenic tobacco plants (NtGp11) overexpressing gamma-glutamylcysteine synthetase (γ-ECS) was tested for tolerance against drought stress. NtGp11 conferred tolerance to drought stress by increased germination rate, water retention, water recovery, chlorophyll, and proline content compared with wild-type plants. Semi-quantitative RT-PCR analysis revealed that the transcript levels of stress-responsive genes were higher in NtGp11 compared with wild-type in response to drought stress. Two-dimensional gel electrophoresis (2-DE) coupled with MALDI TOF-TOF MS/MS analysis has been used to identify 43 differentially expressed proteins in response to drought in wild-type and NtGp11 plants. The results demonstrated the up-accumulation of 58.1% of proteins among which 36%, 24%, and 20% of them were related to stress and defense, carbon metabolism and energy metabolism categories, respectively. Taken together, our results demonstrated that GSH plays an important role in combating drought stress in plants by inducing stress related genes and proteins like HSP70, chalcone synthase, glutathione peroxidase, thioredoxin peroxidase, ACC oxidase, and heme oxygenase I.
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Proteomic profiling of γ-ECS overexpressed transgenic Nicotiana in response to drought stress.
Kumar, Deepak; Datta, Riddhi; Sinha, Ragini; Ghosh, Aparupa; Chattopadhyay, Sharmila
2014-05-20
The contribution of Glutathione (GSH) in drought stress tolerance is an established fact. However, the proteins which are directly or indirectly related to the increased level of GSH in response to drought stress are yet to be known. To explore this, here, transgenic tobacco plants (NtGp 11) overexpressing gamma-glutamylcysteine synthetase (γ-ECS) was tested for tolerance against drought stress. NtGp 11 conferred tolerance to drought stress by increased germination rate, water retention, water recovery, chlorophyll, and proline content compared with wild-type plants. Semi-quantitative RT-PCR analysis revealed that the transcript levels of stress-responsive genes were higher in NtGp 11 compared with wild-type in response to drought stress. Two-dimensional gel electrophoresis (2-DE) coupled with MALDI TOF-TOF MS/MS analysis has been used to identify 43 differentially expressed proteins in response to drought in wild-type and NtGp 11 plants. The results demonstrated the up-accumulation of 58.1% of proteins among which 36%, 24%, and 20% of them were related to stress and defense, carbon metabolism and energy metabolism categories, respectively. Taken together, our results demonstrated that GSH plays an important role in combating drought stress in plants by inducing stress related genes and proteins like HSP70, chalcone synthase, glutathione peroxidase, thioredoxin peroxidase, ACC oxidase, and heme oxygenase I.
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Wei, Tao; Deng, Kejun; Wang, Hongbin; Zhang, Lipeng; Wang, Chunguo; Song, Wenqin; Zhang, Yong; Chen, Chengbin
2018-03-12
In our previous study, drought-resistant transgenic plants of Salvia miltiorrhiza were produced via overexpression of the transcription factor AtDREB1A. To unravel the molecular mechanisms underpinning elevated drought tolerance in transgenic plants, in the present study we compared the global transcriptional profiles of wild-type (WT) and AtDREB1A -expressing transgenic plants using RNA-sequencing (RNA-seq). Using cluster analysis, we identified 3904 differentially expressed genes (DEGs). Compared with WT plants, 423 unigenes were up-regulated in pRD29A::AtDREB1A-31 before drought treatment, while 936 were down-regulated and 1580 and 1313 unigenes were up- and down-regulated after six days of drought. COG analysis revealed that the 'signal transduction mechanisms' category was highly enriched among these DEGs both before and after drought stress. Based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation, DEGs associated with "ribosome", "plant hormone signal transduction", photosynthesis", "plant-pathogen interaction", "glycolysis/gluconeogenesis" and "carbon fixation" are hypothesized to perform major functions in drought resistance in AtDREB1A -expressing transgenic plants. Furthermore, the number of DEGs associated with different transcription factors increased significantly after drought stress, especially the AP2/ERF, bZIP and MYB protein families. Taken together, this study substantially expands the transcriptomic information for S. miltiorrhiza and provides valuable clues for elucidating the mechanism of AtDREB1A-mediated drought tolerance in transgenic plants.
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Topography may mitigate drought effects on vegetation along a hillslope gradient
Sandra Hawthorne; Chelcy Ford Miniat
2017-01-01
Topography may mitigate drought effects on vegetation along a hillslope gradient through redistribution of soil moisture. We examined the interaction of topography, climate, soil moisture, and transpiration in a lowâelevation, mixedâhardwood forest in the southern Appalachian Mountains. The effects of meteorological variation (wet and dry years) and topographic...
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Li, Xiangnan; Tan, Dun-Xian; Jiang, Dong; Liu, Fulai
2016-10-01
Melatonin is involved in multiple plant developmental processes and various stress responses. To explore the roles of melatonin played as well as its association with abscisic acid (ABA) in a process of drought priming-induced cold tolerance (DPICT), a wild-type barley and its ABA-deficient mutant Az34 counterpart were selected for comparison, in which the effects of melatonin application (either foliarly or rhizospherically) and/or drought priming on the cold tolerance of both types of barleys were systematically investigated. It was demonstrated that the early drought priming induced an increase of endogenous melatonin production, which is not ABA dependent. In addition, exogenously applied melatonin resulted in higher ABA concentration in the drought-primed plants than in the nonprimed plants when exposed to cold stress, indicating that ABA responded in a drought-dependent manner. The interplay of melatonin and ABA leads to plants maintaining better water status. Drought priming-induced melatonin accumulation enhanced the antioxidant capacity in both chloroplasts and mitochondria, which sustained the photosynthetic electron transport in photosynthetic apparatus of the plants under cold stress. These results suggest that the exogenous melatonin application enhances the DPICT by modulating subcellular antioxidant systems and ABA levels in barley. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
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Molecular and systems approaches towards drought-tolerant canola crops.
Zhu, Mengmeng; Monroe, J Grey; Suhail, Yasir; Villiers, Florent; Mullen, Jack; Pater, Dianne; Hauser, Felix; Jeon, Byeong Wook; Bader, Joel S; Kwak, June M; Schroeder, Julian I; McKay, John K; Assmann, Sarah M
2016-06-01
1169 I. 1170 II. 1170 III. 1172 IV. 1176 V. 1181 VI. 1182 1183 References 1183 SUMMARY: Modern agriculture is facing multiple challenges including the necessity for a substantial increase in production to meet the needs of a burgeoning human population. Water shortage is a deleterious consequence of both population growth and climate change and is one of the most severe factors limiting global crop productivity. Brassica species, particularly canola varieties, are cultivated worldwide for edible oil, animal feed, and biodiesel, and suffer dramatic yield loss upon drought stress. The recent release of the Brassica napus genome supplies essential genetic information to facilitate identification of drought-related genes and provides new information for agricultural improvement in this species. Here we summarize current knowledge regarding drought responses of canola, including physiological and -omics effects of drought. We further discuss knowledge gained through translational biology based on discoveries in the closely related reference species Arabidopsis thaliana and through genetic strategies such as genome-wide association studies and analysis of natural variation. Knowledge of drought tolerance/resistance responses in canola together with research outcomes arising from new technologies and methodologies will inform novel strategies for improvement of drought tolerance and yield in this and other important crop species. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.
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Roles of plant hormones and anti-apoptosis genes during drought stress in rice (Oryza sativa L.).
Ubaidillah, Mohammad; Safitri, Fika Ayu; Jo, Jun-Hyeon; Lee, Sang-Kyu; Hussain, Adil; Mun, Bong-Gyu; Chung, Il Kyung; Yun, Byung-Wook; Kim, Kyung-Min
2016-12-01
We previously identified the rice (Oryza sativa) senescence-associated gene OsSAP which encodes a highly conserved protein involved in anti-apoptotic activity. This novel Bax suppressor-related gene regulates tolerance to multiple stresses in yeast. Here, we show the effects of drought stress on leaf and root tissues of plants over-expressing OsSAP in relation to the levels of phytohormones, abscisic acid (ABA), jasmonic acid (JA), indole-3-carboxylic acid (ICA), gibberellic acid (GA 3 ), and zeatin. Results showed that rice plants over-expressing SAP were tolerant to drought stress compared to wild type and the plants over-expressing AtBI-1, which is a homolog of the human Bax inhibitor-1 in Arabidopsis. ABA and JA levels in OsSAP and AtBI-1 transgenic plants consistently increased up to at least 3 days after drought treatment, whereas lower GA 3 levels were recorded during early drought period. Comparison between control and transgenic plants overexpressing anti-apoptosis genes OsSAP and AtBI-1 resulted in different patterns of hormone levels, indicating that these genes are involved in the plant responses to drought stress and present an opportunity for further study on drought stress tolerance in rice and other plant species.
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Abid, Muhammad; Ali, Shafaqat; Qi, Lei Kang; Zahoor, Rizwan; Tian, Zhongwei; Jiang, Dong; Snider, John L; Dai, Tingbo
2018-03-15
Defining the metabolic strategies used by wheat to tolerate and recover from drought events will be important for ensuring yield stability in the future, but studies addressing this critical research topic are limited. To this end, the current study quantified the physiological, biochemical, and agronomic responses of a drought tolerant and drought sensitive cultivar to periods of water deficit and recovery. Drought stress caused a reversible decline in leaf water relations, membrane stability, and photosynthetic activity, leading to increased reactive oxygen species (ROS) generation, lipid peroxidation and membrane injury. Plants exhibited osmotic adjustment through the accumulation of soluble sugars, proline, and free amino acids and increased enzymatic and non-enzymatic antioxidant activities. After re-watering, leaf water potential, membrane stability, photosynthetic processes, ROS generation, anti-oxidative activities, lipid peroxidation, and osmotic potential completely recovered for moderately stressed plants and did not fully recover in severely stressed plants. Higher photosynthetic rates during drought and rapid recovery after re-watering produced less-pronounced yield declines in the tolerant cultivar than the sensitive cultivar. These results suggested that the plant's ability to maintain functions during drought and to rapidly recover after re-watering during vegetative periods are important for determining final productivity in wheat.
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Ochoa-Hueso, Raúl; Collins, Scott L; Delgado-Baquerizo, Manuel; Hamonts, Kelly; Pockman, William T; Sinsabaugh, Robert L; Smith, Melinda D; Knapp, Alan K; Power, Sally A
2018-03-05
The effects of short-term drought on soil microbial communities remain largely unexplored, particularly at large scales and under field conditions. We used seven experimental sites from two continents (North America and Australia) to evaluate the impacts of imposed extreme drought on the abundance, community composition, richness, and function of soil bacterial and fungal communities. The sites encompassed different grassland ecosystems spanning a wide range of climatic and soil properties. Drought significantly altered the community composition of soil bacteria and, to a lesser extent, fungi in grasslands from two continents. The magnitude of the fungal community change was directly proportional to the precipitation gradient. This greater fungal sensitivity to drought at more mesic sites contrasts with the generally observed pattern of greater drought sensitivity of plant communities in more arid grasslands, suggesting that plant and microbial communities may respond differently along precipitation gradients. Actinobateria, and Chloroflexi, bacterial phyla typically dominant in dry environments, increased their relative abundance in response to drought, whereas Glomeromycetes, a fungal class regarded as widely symbiotic, decreased in relative abundance. The response of Chlamydiae and Tenericutes, two phyla of mostly pathogenic species, decreased and increased along the precipitation gradient, respectively. Soil enzyme activity consistently increased under drought, a response that was attributed to drought-induced changes in microbial community structure rather than to changes in abundance and diversity. Our results provide evidence that drought has a widespread effect on the assembly of microbial communities, one of the major drivers of soil function in terrestrial ecosystems. Such responses may have important implications for the provision of key ecosystem services, including nutrient cycling, and may result in the weakening of plant-microbial interactions and a greater incidence of certain soil-borne diseases. © 2018 John Wiley & Sons Ltd.
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Armada, Elisabeth; Roldán, Antonio; Azcon, Rosario
2014-02-01
The effectiveness of autochthonous plant growth-promoting rhizobacteria was studied in Lavandula dentata and Salvia officinalis growing in a natural arid Mediterranean soil under drought conditions. These bacteria identified as Bacillus megaterium (Bm), Enterobacter sp. (E), Bacillus thuringiensis (Bt), and Bacillus sp. (Bsp). Each bacteria has different potential to meliorate water limitation and alleviating drought stress in these two plant species. B. thuringiensis promoted growth and drought avoidance in Lavandula by increasing K content, by depressing stomatal conductance, and it controlled shoot proline accumulation. This bacterial effect on increasing drought tolerance was related to the decrease of glutathione reductase (GR) and ascorbate peroxidase (APX) that resulted sensitive indexes of lower cellular oxidative damage involved in the adaptative drought response in B. thuringiensis-inoculated Lavandula plants. In contrast, in Salvia, having intrinsic lower shoot/root ratio, higher stomatal conductance and lower APX and GR activities than Lavandula, the bacterial effects on nutritional, physiological and antioxidant enzymatic systems were lower. The benefit of bacteria depended on intrinsic stress tolerance of plant involved. Lavadula demonstrated a greater benefit than Salvia to control drought stress when inoculated with B. thuringiensis. The bacterial drought tolerance assessed as survival, proline, and indolacetic acid production showed the potential of this bacteria to help plants to grow under drought conditions. B. thuringiensis may be used for Lavandula plant establishment in arid environments. Particular characteristic of the plant species as low shoot/root ratio and high stomatal conductance are important factors controlling the bacterial effectiveness improving nutritional, physiological, and metabolic plant activities.
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Tak, Himanshu; Negi, Sanjana; Ganapathi, T R
2017-03-01
Banana is an important fruit crop and its yield is hampered by multiple abiotic stress conditions encountered during its growth. The NAC (NAM, ATAF, and CUC) transcription factors are involved in plant response to biotic and abiotic stresses. In the present study, we studied the induction of banana NAC042 transcription factor in drought and high salinity conditions and its overexpression in transgenic banana to improve drought and salinity tolerance. MusaNAC042 expression was positively associated with stress conditions like salinity and drought and it encoded a nuclear localized protein. Transgenic lines of banana cultivar Rasthali overexpressing MusaNAC042 were generated by Agrobacterium-mediated transformation of banana embryogenic cells and T-DNA insertion was confirmed by PCR and Southern blot analysis. Our results using leaf disc assay indicated that transgenic banana lines were able to tolerate drought and high salinity stress better than the control plants and retained higher level of total chlorophyll and lower level of MDA content (malondialdehyde). Transgenic lines analyzed for salinity (250 mM NaCl) and drought (Soil gravimetric water content 0.15) tolerance showed higher proline content, better Fv/Fm ratio, and lower levels of MDA content than control suggesting that MusaNAC042 may be involved in responses to higher salinity and drought stresses in banana. Expression of several abiotic stress-related genes like those coding for CBF/DREB, LEA, and WRKY factors was altered in transgenic lines indicating that MusaNAC042 is an efficient modulator of abiotic stress response in banana.
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Differential metabolome analysis of field-grown maize kernels in response to drought stress
USDA-ARS?s Scientific Manuscript database
Drought stress constrains maize kernel development and can exacerbate aflatoxin contamination. In order to identify drought responsive metabolites and explore pathways involved in kernel responses, a metabolomics analysis was conducted on kernels from a drought tolerant line, Lo964, and a sensitive ...
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Morphological and Biological alteration of maize root architectures on drought stress
USDA-ARS?s Scientific Manuscript database
Drought tolerance is a complex agronomic trait and root characteristics logically play an important role in determining the response of plants to drought stress. Studies were conducted to investigate genotypic variations in morphological and physiological responses of roots to drought stress in corn...
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Morphological and biological alteration of maize root architectures on drought stress
USDA-ARS?s Scientific Manuscript database
Drought tolerance is a complex agronomic trait and root characteristics logically play an important role in determining the response of plants to drought stress. Studies were conducted to investigate genotypic variations in morphological and physiological responses of roots to drought stress in corn...
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Tolerance or avoidance: drought frequency determines the response of an N2 -fixing tree.
Minucci, Jeffrey M; Miniat, Chelcy Ford; Teskey, Robert O; Wurzburger, Nina
2017-07-01
Climate change is increasing drought frequency, which may affect symbiotic N 2 fixation (SNF), a process that facilitates ecosystem recovery from disturbance. Here, we assessed the effect of drought frequency on the ecophysiology and SNF rate of a common N 2 -fixing tree in eastern US forests. We grew Robinia pseudoacacia seedlings under the same mean soil moisture, but with different drought frequency caused by wet-dry cycles of varying periodicity. We found no effect of drought frequency on final biomass or mean SNF rate. However, seedlings responded differently to wet and dry phases depending on drought frequency. Under low-frequency droughts, plants fixed carbon (C) and nitrogen (N) at similar rates during wet and dry phases. Conversely, under high-frequency droughts, plants fixed C and N at low rates during dry phases and at high rates during wet phases. Our findings suggest that R. pseudoacacia growth is resistant to increased drought frequency because it employs two strategies - drought tolerance or drought avoidance, followed by compensation. SNF may play a role in both by supplying N to leaf tissues for acclimation and by facilitating compensatory growth following drought. Our findings point to SNF as a mechanism for plants and ecosystems to cope with drought. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.
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Survival of soil bacteria during prolonged desiccation.
NASA Technical Reports Server (NTRS)
Chen, M.; Alexander, M.
1973-01-01
A determination was made of the kinds and numbers of bacteria surviving when two soils were maintained in the laboratory under dry conditions for more than half a year. Certain non-spore-forming bacteria were found to survive in the dry condition for long periods. A higher percentage of drought-tolerant than drought-sensitive bacteria was able to grow at low water activities. When they were grown in media with high salt concentrations, bacteria generally became more tolerant of prolonged drought and they persisted longer. The percent of cells in a bacterial population that remained viable when exposed to drought stress varied with the stage of growth.
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Li, Jinjie; Li, Yang; Yin, Zhigang; Jiang, Jihong; Zhang, Minghui; Guo, Xiao; Ye, Zhujia; Zhao, Yan; Xiong, Haiyan; Zhang, Zhanying; Shao, Yujie; Jiang, Conghui; Zhang, Hongliang; An, Gynheung; Paek, Nam-Chon; Ali, Jauhar; Li, Zichao
2017-02-01
Drought is one of the major abiotic stresses that directly implicate plant growth and crop productivity. Although many genes in response to drought stress have been identified, genetic improvement to drought resistance especially in food crops is showing relatively slow progress worldwide. Here, we reported the isolation of abscisic acid, stress and ripening (ASR) genes from upland rice variety, IRAT109 (Oryza sativa L. ssp. japonica), and demonstrated that overexpression of OsASR5 enhanced osmotic tolerance in Escherichia coli and drought tolerance in Arabidopsis and rice by regulating leaf water status under drought stress conditions. Moreover, overexpression of OsASR5 in rice increased endogenous ABA level and showed hypersensitive to exogenous ABA treatment at both germination and postgermination stages. The production of H 2 O 2 , a second messenger for the induction of stomatal closure in response to ABA, was activated in overexpression plants under drought stress conditions, consequently, increased stomatal closure and decreased stomatal conductance. In contrast, the loss-of-function mutant, osasr5, showed sensitivity to drought stress with lower relative water content under drought stress conditions. Further studies demonstrated that OsASR5 functioned as chaperone-like protein and interacted with stress-related HSP40 and 2OG-Fe (II) oxygenase domain containing proteins in yeast and plants. Taken together, we suggest that OsASR5 plays multiple roles in response to drought stress by regulating ABA biosynthesis, promoting stomatal closure, as well as acting as chaperone-like protein that possibly prevents drought stress-related proteins from inactivation. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.
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Szota, Christopher; Farrell, Claire; Koch, John M; Lambers, Hans; Veneklaas, Erik J
2011-10-01
This study describes the physiological response of two co-occurring tree species (Eucalyptus marginata and Corymbia calophylla) to seasonal drought at low- and high-quality restored bauxite mine sites in south-western Australia. Seasonal changes in photosynthesis (A), stomatal conductance (g(s)), leaf water potential (ψ), leaf osmotic potential (ψ), leaf relative water content (RWC) and pressure-volume analysis were captured over an 18-month field study to (i) determine the nature and severity of physiological stress in relation to site quality and (ii) identify any physiological differences between the two species. Root system restriction at the low-quality site reduced maximum rates of gas exchange (g(s) and A) and increased water stress (midday ψ and daily RWC) in both species during drought. Both species showed high stomatal sensitivity during drought; however, E. marginata demonstrated a higher dehydration tolerance where ψ and RWC fell to -3.2 MPa and 73% compared with -2.4 MPa and 80% for C. calophylla. Corymbia calophylla showed lower g(s) and higher ψ and RWC during drought, indicating higher drought tolerance. Pressure-volume curves showed that cell-wall elasticity of E. marginata leaves increased in response to drought, while C. calophylla leaves showed lower osmotic potential at zero turgor in summer than in winter, indicating osmotic adjustment. Both species are clearly able to tolerate seasonal drought at hostile sites; however, by C. calophylla closing stomata earlier in the drought cycle, maintaining a higher water status during drought and having the additional mechanism of osmotic adjustment, it may have a greater capacity to survive extended periods of drought.
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Triazole induced drought tolerance in horse chestnut (Aesculus hippocastanum).
Percival, Glynn C; Noviss, Kelly
2008-11-01
We determined the influence of the triazole derivatives paclobutrazol, penconazole, epixiconazole, propiconazole and myclobutanil on the drought tolerance and post drought recovery of container-grown horse chestnut (Aesculus hippocastanum L.) saplings. Myclobutanil neither conferred drought resistance, as assessed by its effects on a number of physiological and biochemical parameters, nor affected growth parameters measured after recovery from drought. Chlorophyll fluorescence (F(v)/F(m)), photosynthetic rates, total foliar chlorophyll and carotenoid concentrations, foliar proline concentration and superoxide dismutase and catalase activities were consistently higher and leaf necrosis and cellular electrolyte leakage was lower at the end of a 3-week drought in trees treated with paclobutrazol, penconazole, epixiconazole or propiconazole than in control trees. Twelve weeks after drought treatment, leaf area and shoot, root and total plant dry masses were greater in triazole-treated trees than in control trees with the exception of those treated with myclobutanil. In a separate study, trees were subjected to a 2-week drought and then sprayed with paclobutrazol, penconazole, epixiconazole, propiconazole or myclobutanil. Chlorophyll fluorescence, photosynthetic rate, foliar chlorophyll concentration and catalase activity over the following 12 weeks were 20 to 50% higher in triazole-treated trees than in control trees. At the end of the 12-week recovery period, leaf area and shoot, root and total plant dry masses were higher in triazole-treated trees than in control trees, with the exception of trees treated with myclobutanil. Application of triazole derivatives, with the exception of myclobutanil, enhanced tolerance to prolonged drought and, when applied after a 2-week drought, hastened recovery from drought. The magnitude of treatment effects was in the order epixiconazole approximately propiconazole > penconazole > paclobutrazol > myclobutanil.
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Augustine, Sruthy Maria; Cherian, Anoop V; Syamaladevi, Divya P; Subramonian, N
2015-12-01
Plant growth during abiotic stress is a long sought-after trait especially in crop plants in the context of global warming and climate change. Previous studies on leaf epidermal cells have revealed that during normal growth and development, adjacent cells interdigitate anisotropically to form cell morphological patterns known as interlocking marginal lobes (IMLs), involving the cell wall-cell membrane-cortical actin continuum. IMLs are growth-associated cell morphological changes in which auxin-binding protein (ABP), Rho GTPases and actin are known to play important roles. In the present study, we investigated the formation of IMLs under drought stress and found that Erianthus arundinaceus, a drought-tolerant wild relative of sugarcane, develops such growth-related cell morphological patterns under drought stress. Using confocal microscopy, we showed an increasing trend in cortical F-actin intensity in drought-tolerant plants with increasing soil moisture stress. In order to check the role of drought tolerance-related genes in IML formation under soil moisture stress, we adopted a structural data mining strategy and identified indirect connections between the ABPs and heat shock proteins (HSPs). Initial experimental evidence for this connection comes from the high transcript levels of HSP70 observed in drought-stressed Erianthus, which developed anisotropic interdigitation, i.e. IMLs. Subsequently, by overexpressing the E. arundinaceus HSP70 gene (EaHSP70) in sugarcane (Saccharum spp. hybrid), we confirm the role of HSP70 in the formation of anisotropic interdigitation under drought stress. Taken together, our results suggest that EaHSP70 acts as a key regulator in the formation of anisotropic interdigitation in drought-tolerant plants (Erianthus and HSP70 transgenic sugarcane) under moisture stress in an actin-mediated pathway. The possible biological significance of the formation of drought-associated interlocking marginal lobes (DaIMLs) in sugarcane plants upon drought stress is discussed. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.
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Peirone, Laura S; Pereyra Irujo, Gustavo A; Bolton, Alejandro; Erreguerena, Ignacio; Aguirrezábal, Luis A N
2018-01-01
Conventional field phenotyping for drought tolerance, the most important factor limiting yield at a global scale, is labor-intensive and time-consuming. Automated greenhouse platforms can increase the precision and throughput of plant phenotyping and contribute to a faster release of drought tolerant varieties. The aim of this work was to establish a framework of analysis to identify early traits which could be efficiently measured in a greenhouse automated phenotyping platform, for predicting the drought tolerance of field grown soybean genotypes. A group of genotypes was evaluated, which showed variation in their drought susceptibility index (DSI) for final biomass and leaf area. A large number of traits were measured before and after the onset of a water deficit treatment, which were analyzed under several criteria: the significance of the regression with the DSI, phenotyping cost, earliness, and repeatability. The most efficient trait was found to be transpiration efficiency measured at 13 days after emergence. This trait was further tested in a second experiment with different water deficit intensities, and validated using a different set of genotypes against field data from a trial network in a third experiment. The framework applied in this work for assessing traits under different criteria could be helpful for selecting those most efficient for automated phenotyping.
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USDA-ARS?s Scientific Manuscript database
Technical Abstract: This study was aimed to estimate the combining ability, through diallel crosses, of T. cacao genotypes preselected for drought tolerance. The experiment was conducted under greenhouse conditions at the Cacao Research Center (CEPEC), Ilhéus, Bahia, Brazil, in a completely randomiz...
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Soil water extraction, water use, and grain yield by drought tolerant maize on the Texas High Plains
USDA-ARS?s Scientific Manuscript database
Anticipated water shortages pose a challenge to the sustainability of maize (Zea mays L.) production on the Texas High Plains. Adoption of drought tolerant (DT) hybrids is a critical management strategy for maize production under water limited conditions. However, limited information is available co...
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USDA-ARS?s Scientific Manuscript database
Water availability is commonly the most limiting factor to crop production. This study was conducted to map quantitative trait loci (QTL) involved in drought tolerance in wheat (Triticum aestivum L.) to enable their use for marker assisted selection (MAS) in breeding. Using amplified fragment leng...
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Dhurrin content relates to sorghum [sorghum bicolor (L.) Moench] seedling growth in marginal soils
USDA-ARS?s Scientific Manuscript database
Dhurrin content in leaves of mature sorghum plant is a quantitative measure of the level of pre-and postflowering drought tolerance (Burke et al., 2013). Postflowering drought tolerance in sorghum is linked to the staygreen (delayed senescence) trait (Howarth, 2000; Rosenow et al., 1977) which has ...
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Dhurrin content relates to sorghum (Sorghum bicolor (L) Moench) seedling growth in marginal soils.
USDA-ARS?s Scientific Manuscript database
Dhurrin content in leaves of mature sorghum plant is a quantitative measure of the level of pre-and postflowering drought tolerance (Burke et al., 2013). Postflowering drought tolerance in sorghum is linked to the staygreen (delayed senescence) trait (Howarth, 2000; Rosenow et al., 1977) which has b...
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USDA-ARS?s Scientific Manuscript database
Genomic-assisted breeding and transgenic approaches to crop improvement are presently targeting phenotypic traits that allegedly confer drought tolerance. A news feature published in Nature Biotechnology last year suggests that these efforts may not be proceeding with sufficient haste, considering t...
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USDA-ARS?s Scientific Manuscript database
This protocol describes a method by which a large collection of the leafy green vegetable lettuce (Lactuca sativa L.) germplasm was screened for likely drought-tolerance traits. Fresh water availability for agricultural use is a growing concern across the United States as well as many regions of th...
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Katiyar, Amit; Smita, Shuchi; Muthusamy, Senthilkumar K.; Chinnusamy, Viswanathan; Pandey, Dev M.; Bansal, Kailash C.
2015-01-01
Small non-coding RNAs (sRNAs) namely microRNAs (miRNAs) and trans-acting small interfering RNAs (tasi-RNAs) play a crucial role in post-transcriptional regulation of gene expression and thus the control plant development and stress responses. In order to identify drought-responsive miRNAs and tasi-RNAs in sorghum, we constructed small RNA libraries from a drought tolerant (M35-1) and susceptible (C43) sorghum genotypes grown under control and drought stress conditions, and sequenced by Illumina Genome Analyzer IIx. Ninety seven conserved and 526 novel miRNAs representing 472 unique miRNA families were identified from sorghum. Ninety-six unique miRNAs were found to be regulated by drought stress, of which 32 were up- and 49 were down-regulated (fold change ≥ 2 or ≤ −2) at least in one genotype, while the remaining 15 miRNAs showed contrasting drought-regulated expression pattern between genotypes. A maximum of 17 and 18 miRNAs was differentially regulated under drought stress condition in the sensitive and tolerant genotypes, respectively. These results suggest that genotype dependent stress responsive regulation of miRNAs may contribute, at least in part, to the differential drought tolerance of sorghum genotypes. We also identified two miR390-directed TAS3 gene homologs and the auxin response factors as tasi-RNA targets. We predicted more than 1300 unique target genes for the novel and conserved miRNAs. These target genes were predicted to be involved in different cellular, metabolic, response to stimulus, biological regulation, and developmental processes. Genome-wide identification of stress-responsive miRNAs, tasi-RNAs and their targets identified in this study will be useful in unraveling the molecular mechanisms underlying drought stress responses and genetic improvement of biomass production and stress tolerance in sorghum. PMID:26236318
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Wang, Wen-Hua; Chen, Juan; Liu, Ting-Wu; Chen, Juan; Han, Ai-Dong; Simon, Martin; Dong, Xue-Jun; He, Jun-Xian; Zheng, Hai-Lei
2014-01-01
Production per amount of water used (water use efficiency, WUE) is closely correlated with drought tolerance. Although stomatal aperture can regulate WUE, the underlying molecular mechanisms are still unclear. Previous reports revealed that stomatal closure was inhibited in the calcium-sensing receptor (CAS) antisense line of Arabidopsis (CASas). Here it is shown that decreased drought tolerance and WUE of CASas was associated with higher stomatal conductance due to improper regulation of stomatal aperture, rather than any change of stomatal density. CASas plants also had a lower CO2 assimilation rate that was attributed to a lower photosynthetic electron transport rate, leading to higher chlorophyll fluorescence. Gene co-expression combined with analyses of chlorophyll content and transcription levels of photosynthesis-related genes indicate that CAS is involved in the formation of the photosynthetic electron transport system. These data suggest that CAS regulates transpiration and optimizes photosynthesis by playing important roles in stomatal movement and formation of photosynthetic electron transport, thereby regulating WUE and drought tolerance.
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USDA-ARS?s Scientific Manuscript database
Preharvest A. flavus infection is usually exacerbated when maize plants suffer drought stress in the late grain-fill stage. However, the field observation suggests that drought-tolerant maize lines displayed less aflatoxin contamination under the stress in comparison with the drought-sensitive maize...
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Toward an index of desiccation times to tree mortality under drought
USDA-ARS?s Scientific Manuscript database
Research in plant hydraulics has provided important insights into plant responses to drought and species absolute drought tolerance. However our ability to predict when plants will die under extreme drought may be limited by a lack of knowledge with regards to the dynamics of plant desiccation from ...
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Vinnakota, Rajesh; Ramakrishnan, Anantha Maharasi; Samdani, A; Venugopal, M Anjali; Ram, B Sri; Krishnan, S Navaneetha; Murugesan, Dhandapani; Sankaranarayanan, Kavitha
2016-11-01
Climate change drastically affects the cultivation of rice, and its production is affected significantly by water stress. Adaptation of a plant to water deficit conditions is orchestrated by efficient water uptake and a stringently regulated water loss. Transpiration remains the major means of water loss from plants and is mediated by microscopic pores called stomata. Stomatal aperture gating is facilitated by ion channels and aquaporins (AQPs) which regulate the turgidity of the guard cells. In a similar manner, efficient water uptake by the roots is regulated by the presence of AQPs in the plasma membrane of root cells. In this study, we compare the efficiency of transmembrane water permeability in guard cells and root protoplasts from drought-tolerant and sensitive varieties of Oryza sativa L. In this report, we studied the transmembrane osmotic water permeability (P os ) of guard cell and root protoplasts of drought-sensitive and tolerant cultivars. The guard cells isolated from the drought-sensitive lowland rice variety ADT-39 show significant low osmotic permeability than the drought-tolerant rice varieties of Anna (lowland) and Dodda Byra Nellu (DBN) (upland local land rice). There is no significant difference in relative gene expression patterns of PIPs (Plasma membrane Intrinsic Proteins "PIP1" and "PIP2" subfamilies) in guard cells isolated from ADT-39 and Anna. While the expression levels of AQP genes remain the same between ADT-39 and Anna, there is a drastic difference in their osmotic permeability in the guard cells in spite of a higher number of stomata in Anna and DBN, hinting at a more efficient gating mechanism of AQP in the stomata of the drought-tolerant varieties studied.
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Meng, Lai-Sheng; Yao, Shun-Qiao
2015-09-01
One goal of modern agriculture is the improvement of plant drought tolerance and water-use efficiency (WUE). Although stomatal density has been linked to WUE, the causal molecular mechanisms and engineered alternations of this relationship are not yet fully understood. Moreover, YODA (YDA), which is a MAPKK kinase gene, negatively regulates stomatal development. BR-INSENSITIVE 2 interacts with phosphorylates and inhibits YDA. However, whether YDA is modulated in the transcriptional level is still unclear. Plants lacking ANGUSTIFOLIA3 (AN3) activity have high drought stress tolerance because of low stomatal densities and improved root architecture. Such plants also exhibit enhanced WUE through declining transpiration without a demonstrable reduction in biomass accumulation. AN3 negatively regulated YDA expression at the transcriptional level by target-gene analysis. Chromatin immunoprecipitation analysis indicated that AN3 was associated with a region of the YDA promoter in vivo. YDA mutation significantly decreased the stomatal density and root length of an3 mutant, thus proving the participation of YDA in an3 drought tolerance and WUE enhancement. These components form an AN3-YDA complex, which allows the integration of water deficit stress signalling into the production or spacing of stomata and cell proliferation, thus leading to drought tolerance and enhanced WUE. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.
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Forages and Pastures Symposium: development of and field experience with drought-tolerant maize.
Soderlund, S; Owens, F N; Fagan, C
2014-07-01
Drought-tolerant maize hybrids currently are being marketed by several seed suppliers. Such hybrids were developed by phenotypic and marker-assisted selection or through genetic modification and tested by exposing these hybrids to various degrees of water restriction. As drought intensifies, crop yields and survival progressively decline. Water need differs among plants due to differences in root structure, evaporative loss, capacity to store water or enter temporary dormancy, and plant genetics. Availability of water differs widely not only with rainfall and irrigation but also with numerous soil and agronomic factors (e.g., soil type, slope, seeding rates, tillage practices). Reduced weed competition, enhanced pollen shed and silk production, and deep, robust root growth help to reduce the negative impacts of drought. Selected drought-tolerant maize hybrids have consistently yielded more grain even when drought conditions are not apparent either due to reduced use of soil water reserves before water restriction or due to greater tolerance of intermittent water shortages. In DuPont Pioneer trials, whole plant NDF digestibility of maize increased with water restriction, perhaps due to an increased leaf to stem ratio. Efficiency of water use, measured as dry matter or potential milk yield from silage per unit of available water, responded quadratically to water restriction, first increasing slightly but then decreasing as water restriction increased. For grain production, water restriction has its greatest negative impact during or after silking through reducing the number of kernels and reducing kernel filling. For silage production, water restriction during the vegetative growth stage negatively impacts plant height and biomass yield. Earlier planting and shorter season maize hybrids help to avoid midsummer heat stress during pollination and can reduce the number of irrigation events needed. Although drought tolerance of maize hybrids has been improved due to genetic selection or biotech approaches, selecting locally adapted hybrids or crops, adjusting seeding rates, and modifying tillage and irrigation practices are important factors that can improve efficiency of use of available water by grain and forage crops.
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Tu, Mingxing; Wang, Xianhang; Feng, Tongying; Sun, Xiaomeng; Wang, Yaqiong; Huang, Li; Gao, Min; Wang, Yuejin; Wang, Xiping
2016-11-01
Drought is one of the most serious factors that limit agricultural productivity and there is considerable interest in understanding the molecular bases of drought responses and their regulation. While numbers of basic leucine zipper (bZIP) transcription factors (TFs) are known to play key roles in response of plants to various abiotic stresses, only a few group K bZIP TFs have been functionally characterized in the context of stress signaling. In this study, we characterized the expression of the grape (Vitis vinifera) group K bZIP gene, VlbZIP36, and found evidence for its involvement in response to drought and the stress-associated phytohormone abscisic acid (ABA). Transgenic Arabidopsis thaliana lines over-expressing VlbZIP36 under the control of a constitutive promoter showed enhanced dehydration tolerance during the seed germination stage, as well as in the seedling and mature plant stages. The results indicated that VlbZIP36 plays a role in drought tolerance by improving the water status, through limiting water loss, and mitigating cellular damage. The latter was evidenced by reduced cell death, lower electrolyte leakage in the transgenic plants, as well as by increased activities of antioxidant enzymes. We concluded that VlbZIP36 enhances drought tolerance through the transcriptional regulation of ABA-/stress-related genes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
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A banana aquaporin gene, MaPIP1;1, is involved in tolerance to drought and salt stresses
2014-01-01
Background Aquaporin (AQP) proteins function in transporting water and other small molecules through the biological membranes, which is crucial for plants to survive in drought or salt stress conditions. However, the precise role of AQPs in drought and salt stresses is not completely understood in plants. Results In this study, we have identified a PIP1 subfamily AQP (MaPIP1;1) gene from banana and characterized it by overexpression in transgenic Arabidopsis plants. Transient expression of MaPIP1;1-GFP fusion protein indicated its localization at plasma membrane. The expression of MaPIP1;1 was induced by NaCl and water deficient treatment. Overexpression of MaPIP1;1 in Arabidopsis resulted in an increased primary root elongation, root hair numbers and survival rates compared to WT under salt or drought conditions. Physiological indices demonstrated that the increased salt tolerance conferred by MaPIP1;1 is related to reduced membrane injury and high cytosolic K+/Na+ ratio. Additionally, the improved drought tolerance conferred by MaPIP1;1 is associated with decreased membrane injury and improved osmotic adjustment. Finally, reduced expression of ABA-responsive genes in MaPIP1;1-overexpressing plants reflects their improved physiological status. Conclusions Our results demonstrated that heterologous expression of banana MaPIP1;1 in Arabidopsis confers salt and drought stress tolerances by reducing membrane injury, improving ion distribution and maintaining osmotic balance. PMID:24606771
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Bi, Huihui; Shi, Jianxin; Kovalchuk, Natalia; Luang, Sukanya; Bazanova, Natalia; Chirkova, Larissa; Zhang, Dabing; Shavrukov, Yuri; Stepanenko, Anton; Tricker, Penny; Langridge, Peter; Hrmova, Maria; Lopato, Sergiy; Borisjuk, Nikolai
2018-05-14
Transcription factors regulate multiple networks, mediating the responses of organisms to stresses, including drought. Here we investigated the role of the wheat transcription factor TaSHN1 in crop growth and drought tolerance. TaSHN1, isolated from bread wheat, was characterised for molecular interactions and functionality. The overexpression of TaSHN1 in wheat was followed by the evaluation of T 2 and T 3 transgenic lines for drought tolerance, growth and yield components. Leaf surface changes were analysed by light microscopy, SEM, TEM and GC-MS/GC-FID. TaSHN1 behaves as a transcriptional activator in a yeast transactivation assay and binds stress-related DNA cis-elements, determinants of which were revealed using 3D molecular modelling. The overexpression of TaSHN1 in transgenic wheat did not result in a yield penalty under the controlled plant growth conditions of a glasshouse. Transgenic lines had significantly lower stomatal density and leaf water loss, and exhibited improved recovery after severe drought, compared to control plants. The comparative analysis of cuticular waxes revealed an increased accumulation of alkanes in leaves of transgenic lines. Our data demonstrate that TaSHN1 may operate as a positive modulator of drought stress tolerance. Positive attributes could be mediated through an enhanced accumulation of alkanes and reduced stomatal density. This article is protected by copyright. All rights reserved.
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Yu, Tai-Fei; Xu, Zhao-Shi; Guo, Jin-Kao; Wang, Yan-Xia; Abernathy, Brian; Fu, Jin-Dong; Chen, Xiao; Zhou, Yong-Bin; Chen, Ming; Ye, Xing-Guo; Ma, You-Zhi
2017-01-01
Cold shock proteins (CSPs) enhance acclimatization of bacteria to adverse environmental circumstances. The Escherichia coli CSP genes CspA and CspB were modified to plant-preferred codon sequences and named as SeCspA and SeCspB. Overexpression of exogenous SeCspA and SeCspB in transgenic Arabidopsis lines increased germination rates, survival rates, and increased primary root length compared to control plants under drought and salt stress. Investigation of several stress-related parameters in SeCspA and SeCspB transgenic wheat lines indicated that these lines possessed stress tolerance characteristics, including lower malondialdehyde (MDA) content, lower water loss rates, lower relative Na+ content, and higher chlorophyll content and proline content than the control wheat plants under drought and salt stresses. RNA-seq and qRT-PCR expression analysis showed that overexpression of SeCsp could enhance the expression of stress-responsive genes. The field experiments showed that the SeCspA transgenic wheat lines had great increases in the 1000-grain weight and grain yield compared to the control genotype under drought stress conditions. Significant differences in the stress indices revealed that the SeCspA transgenic wheat lines possessed significant and stable improvements in drought tolerance over the control plants. No such improvement was observed for the SeCspB transgenic lines under field conditions. Our results indicated that SeCspA conferred drought tolerance and improved physiological traits in wheat plants. PMID:28281578
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Zeng, Changying; Ding, Zehong; Zhou, Fang; Zhou, Yufei; Yang, Ruiju; Yang, Zi; Wang, Wenquan; Peng, Ming
2017-12-12
Background : Cassava, an important tropical crop, has remarkable drought tolerance, but is very sensitive to cold. The growth, development, and root productivity of cassava are all adversely affected under cold and drought. Methods : To profile the transcriptional response to cold and drought stresses, cassava seedlings were respectively subjected to 0, 6, 24, and 48 h of cold stress and 0, 4, 6, and 10 days of drought stress. Their folded leaves, fully extended leaves, and roots were respectively investigated using RNA-seq. Results : Many genes specifically and commonly responsive to cold and drought were revealed: genes related to basic cellular metabolism, tetrapyrrole synthesis, and brassinosteroid metabolism exclusively responded to cold; genes related to abiotic stress and ethylene metabolism exclusively responded to drought; and genes related to cell wall, photosynthesis, and carbohydrate metabolism, DNA synthesis/chromatic structure, abscisic acid and salicylic acid metabolism, and calcium signaling commonly responded to both cold and drought. Discussion : Combined with cold- and/or drought-responsive transcription factors, the regulatory networks responding to cold and drought in cassava were constructed. All these findings will improve our understanding of the specific and common responses to cold and drought in cassava, and shed light on genetic improvement of cold and drought tolerance in cassava.
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The shifting influence of drought and heat stress for crops in northeast Australia.
Lobell, David B; Hammer, Graeme L; Chenu, Karine; Zheng, Bangyou; McLean, Greg; Chapman, Scott C
2015-11-01
Characterization of drought environment types (ETs) has proven useful for breeding crops for drought-prone regions. Here, we consider how changes in climate and atmospheric carbon dioxide (CO2 ) concentrations will affect drought ET frequencies in sorghum and wheat systems of northeast Australia. We also modify APSIM (the Agricultural Production Systems Simulator) to incorporate extreme heat effects on grain number and weight, and then evaluate changes in the occurrence of heat-induced yield losses of more than 10%, as well as the co-occurrence of drought and heat. More than six million simulations spanning representative locations, soil types, management systems, and 33 climate projections led to three key findings. First, the projected frequency of drought decreased slightly for most climate projections for both sorghum and wheat, but for different reasons. In sorghum, warming exacerbated drought stresses by raising the atmospheric vapor pressure deficit and reducing transpiration efficiency (TE), but an increase in TE due to elevated CO2 more than offset these effects. In wheat, warming reduced drought stress during spring by hastening development through winter and reducing exposure to terminal drought. Elevated CO2 increased TE but also raised radiation-use efficiency and overall growth rates and water use, thereby offsetting much of the drought reduction from warming. Second, adding explicit effects of heat on grain number and grain size often switched projected yield impacts from positive to negative. Finally, although average yield losses associated with drought will remain generally higher than that for heat stress for the next half century, the relative importance of heat is steadily growing. This trend, as well as the likely high degree of genetic variability in heat tolerance, suggests that more emphasis on heat tolerance is warranted in breeding programs. At the same time, work on drought tolerance should continue with an emphasis on drought that co-occurs with extreme heat. © 2015 John Wiley & Sons Ltd.
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Pan, Yanglu; Hu, Xin; Li, Chunyan; Xu, Xing; Su, Chenggang; Li, Jinhua; Song, Hongyuan; Zhang, Xingguo; Pan, Yu
2017-01-01
The basic leucine zipper (bZIP) transcription factors have crucial roles in plant stress responses. In this study, the bZIP family gene SlbZIP38 (GenBank accession No: XM004239373) was isolated from a tomato (Solanum lycopersicum cv. Ailsa Craig) mature leaf cDNA library. The DNA sequence of SlbZIP38 encodes a protein of 484 amino acids, including a highly conserved bZIP DNA-binding domain in the C-terminal region. We found that SlbZIP38 was differentially expressed in various organs of the tomato plant and was downregulated by drought, salt stress, and abscisic acid (ABA). However, overexpression of SlbZIP38 significantly decreased drought and salt stress tolerance in tomatoes (Ailsa Craig). The findings that SlbZIP38 overexpression reduced the chlorophyll and free proline content in leaves but increased the malondialdehyde content may explain the reduced drought and salt tolerance observed in these lines. These results suggest that SlbZIP38 is a negative regulator of drought and salt resistance that acts by modulating ABA signaling. PMID:29261143
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Kholová, Jana; Hash, C. T.; Kumar, P. Lava; Yadav, Rattan S.; Kočová, Marie; Vadez, Vincent
2010-01-01
It was previously shown that pearl millet genotypes carrying a terminal drought tolerance quantitative trait locus (QTL) had a lower transpiration rate (Tr; g cm−2 d−1) under well-watered conditions than sensitive lines. Here experiments were carried out to test whether this relates to leaf abscisic acid (ABA) and Tr concentration at high vapour pressure deficit (VPD), and whether that leads to transpiration efficiency (TE) differences. These traits were measured in tolerant/sensitive pearl millet genotypes, including near-isogenic lines introgressed with a terminal drought tolerance QTL (NIL-QTLs). Most genotypic differences were found under well-watered conditions. ABA levels under well-watered conditions were higher in tolerant genotypes, including NIL-QTLs, than in sensitive genotypes, and ABA did not increase under water stress. Well-watered Tr was lower in tolerant than in sensitive genotypes at all VPD levels. Except for one line, Tr slowed down in tolerant lines above a breakpoint at 1.40–1.90 kPa, with the slope decreasing >50%, whereas sensitive lines showed no change in that Tr response across the whole VPD range. It is concluded that two water-saving (avoidance) mechanisms may operate under well-watered conditions in tolerant pearl millet: (i) a low Tr even at low VPD conditions, which may relate to leaf ABA; and (ii) a sensitivity to higher VPD that further restricts Tr, which suggests the involvement of hydraulic signals. Both traits, which did not lead to TE differences, could contribute to absolute water saving seen in part due to dry weight increase differences. This water saved would become critical for grain filling and deserves consideration in the breeding of terminal drought-tolerant lines. PMID:20142425
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Kholová, Jana; Hash, C T; Kumar, P Lava; Yadav, Rattan S; Kocová, Marie; Vadez, Vincent
2010-03-01
It was previously shown that pearl millet genotypes carrying a terminal drought tolerance quantitative trait locus (QTL) had a lower transpiration rate (Tr; g cm(-2) d(-1)) under well-watered conditions than sensitive lines. Here experiments were carried out to test whether this relates to leaf abscisic acid (ABA) and Tr concentration at high vapour pressure deficit (VPD), and whether that leads to transpiration efficiency (TE) differences. These traits were measured in tolerant/sensitive pearl millet genotypes, including near-isogenic lines introgressed with a terminal drought tolerance QTL (NIL-QTLs). Most genotypic differences were found under well-watered conditions. ABA levels under well-watered conditions were higher in tolerant genotypes, including NIL-QTLs, than in sensitive genotypes, and ABA did not increase under water stress. Well-watered Tr was lower in tolerant than in sensitive genotypes at all VPD levels. Except for one line, Tr slowed down in tolerant lines above a breakpoint at 1.40-1.90 kPa, with the slope decreasing >50%, whereas sensitive lines showed no change in that Tr response across the whole VPD range. It is concluded that two water-saving (avoidance) mechanisms may operate under well-watered conditions in tolerant pearl millet: (i) a low Tr even at low VPD conditions, which may relate to leaf ABA; and (ii) a sensitivity to higher VPD that further restricts Tr, which suggests the involvement of hydraulic signals. Both traits, which did not lead to TE differences, could contribute to absolute water saving seen in part due to dry weight increase differences. This water saved would become critical for grain filling and deserves consideration in the breeding of terminal drought-tolerant lines.
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Magwanga, Richard Odongo; Lu, Pu; Kirungu, Joy Nyangasi; Lu, Hejun; Wang, Xingxing; Cai, Xiaoyan; Zhou, Zhongli; Zhang, Zhenmei; Salih, Haron; Wang, Kunbo; Liu, Fang
2018-01-15
Late embryogenesis abundant (LEA) proteins are large groups of hydrophilic proteins with major role in drought and other abiotic stresses tolerance in plants. In-depth study and characterization of LEA protein families have been carried out in other plants, but not in upland cotton. The main aim of this research work was to characterize the late embryogenesis abundant (LEA) protein families and to carry out gene expression analysis to determine their potential role in drought stress tolerance in upland cotton. Increased cotton production in the face of declining precipitation and availability of fresh water for agriculture use is the focus for breeders, cotton being the backbone of textile industries and a cash crop for many countries globally. In this work, a total of 242, 136 and 142 LEA genes were identified in G. hirsutum, G. arboreum and G. raimondii respectively. The identified genes were classified into eight groups based on their conserved domain and phylogenetic tree analysis. LEA 2 were the most abundant, this could be attributed to their hydrophobic character. Upland cotton LEA genes have fewer introns and are distributed in all chromosomes. Majority of the duplicated LEA genes were segmental. Syntenic analysis showed that greater percentages of LEA genes are conserved. Segmental gene duplication played a key role in the expansion of LEA genes. Sixty three miRNAs were found to target 89 genes, such as miR164, ghr-miR394 among others. Gene ontology analysis revealed that LEA genes are involved in desiccation and defense responses. Almost all the LEA genes in their promoters contained ABRE, MBS, W-Box and TAC-elements, functionally known to be involved in drought stress and other stress responses. Majority of the LEA genes were involved in secretory pathways. Expression profile analysis indicated that most of the LEA genes were highly expressed in drought tolerant cultivars Gossypium tomentosum as opposed to drought susceptible, G. hirsutum. The tolerant genotypes have a greater ability to modulate genes under drought stress than the more susceptible upland cotton cultivars. The finding provides comprehensive information on LEA genes in upland cotton, G. hirsutum and possible function in plants under drought stress.
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NASA Astrophysics Data System (ADS)
Lucas, M.; Miura, T.; Trauernicht, C.; Frazier, A. G.
2017-12-01
A drought which results in prolonged and extended deficit in naturally available water supply and creates multiple stresses across ecosystems is classified as an ecological drought. Detecting and understanding the dynamics and response of such droughts in tropical systems, specifically across various vegetation and climatic gradients is fairly undetermined, yet increasingly important for better understandings of the ecological effects of drought. To understanding the link between what lengths and intensities of known meteorological drought triggers detectable ecological vegetation responses, a landscape scale regression analysis evaluating the response (slope) and relationship strength (R-squared) of several cumulative SPI (standard precipitation index) lengths(1, 3, 6, 12, 18, 24, 36, 48, and 60 month), to various satellite derived monthly vegetation indices anomalies (NDVI, EVI, EVI2, and LSWI) was performed across a matrix of dominant vegetation covers (grassland, shrubland, and forest) and climatic moisture zones (arid, dry, mesic, and wet). The nine different SPI lags across these climactic and vegetation gradients was suggest that stronger relationships and steeper slopes were found in dryer climates (across all vegetation covers) and finer vegetation types (across all moisture zones). Overall NDVI, EVI and EVI2 showed the best utility in these dryer climatic zones across all vegetation types. Within arid and dry areas "best" fits showed increasing lengths of cumulative SPI were with increasing vegetation coarseness respectively. Overall these findings suggest that rainfall driven drought may have a stronger impact on the ecological condition of vegetation in water limited systems with finer vegetation types ecologically responding more rapidly to meteorological drought events than coarser woody vegetation systems. These results suggest that previously and newly documented trends of decreasing rainfall and increasing drought in Hawaiian drylands may have drastic and lasting impacts on these unique ecosystems.
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Zhang, Dong-Ping; Zhou, Yong; Yin, Jian-Feng; Yan, Xue-Jiao; Lin, Sheng; Xu, Wei-Feng; Baluška, František; Wang, Yi-Ping; Xia, Yi-Ji; Liang, Guo-hua; Liang, Jian-Sheng
2015-10-01
Heterotrimeric GTP-binding protein (G-protein)-mediated abscisic acid (ABA) and drought-stress responses have been documented in numerous plant species. However, our understanding of the function of rice G-protein subunits in ABA signalling and drought tolerance is limited. In this study, the function of G-protein subunits in ABA response and drought resistance in rice plants was explored. It was found that the transcription level of qPE9-1 (rice Gγ subunit) gradually decreased with increasing ABA concentration and the lack of qPE9-1 showed an enhanced drought tolerance in rice plants. In contrast, mRNA levels of RGB1 (rice Gβ subunit) were significantly upregulated by ABA treatment and the lack of RGB1 led to reduced drought tolerance. Furthermore, the results suggested that qPE9-1 negatively regulates the ABA response by suppressing the expression of key transcription factors involved in ABA and stress responses, while RGB1 positively regulates ABA biosynthesis by upregulating NCED gene expression under both normal and drought stress conditions. Taken together, it is proposed that RGB1 is a positive regulator of the ABA response and drought adaption in rice plants, whereas qPE9-1 is modulated by RGB1 and functions as a negative regulator in the ABA-dependent drought-stress responses. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.
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Tan, Wenrong; Zhang, Dawei; Zhou, Huapeng; Zheng, Ting; Yin, Yanhai; Lin, Honghui
2018-04-01
Drought is a major threat to plant growth and crop productivity. The phytohormone abscisic acid (ABA) plays a critical role in plant response to drought stress. Although ABA signaling-mediated drought tolerance has been widely investigated in Arabidopsis thaliana, the feedback mechanism and components negatively regulating this pathway are less well understood. Here we identified a member of Arabidopsis HD-ZIP transcription factors HAT1 which can interacts with and be phosphorylated by SnRK2s. hat1hat3, loss-of-function mutant of HAT1 and its homolog HAT3, was hypersensitive to ABA in primary root inhibition, ABA-responsive genes expression, and displayed enhanced drought tolerance, whereas HAT1 overexpressing lines were hyposensitive to ABA and less tolerant to drought stress, suggesting that HAT1 functions as a negative regulator in ABA signaling-mediated drought response. Furthermore, expression levels of ABA biosynthesis genes ABA3 and NCED3 were repressed by HAT1 directly binding to their promoters, resulting in the ABA level was increased in hat1hat3 and reduced in HAT1OX lines. Further evidence showed that both protein stability and binding activity of HAT1 was repressed by SnRK2.3 phosphorylation. Overexpressing SnRK2.3 in HAT1OX transgenic plant made a reduced HAT1 protein level and suppressed the HAT1OX phenotypes in ABA and drought response. Our results thus establish a new negative regulation mechanism of HAT1 which helps plants fine-tune their drought responses.
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Fábián, Attila; Jäger, Katalin; Rakszegi, Mariann; Barnabás, Beáta
2011-04-01
The aim of the present work was to reveal the histological alterations triggered in developing wheat kernels by soil drought stress during early seed development resulting in yield losses at harvest. For this purpose, observations were made on the effect of drought stress, applied in a controlled environment from the 5th to the 9th day after pollination, on the kernel morphology, starch content and grain yield of the drought-sensitive Cappelle Desprez and drought-tolerant Plainsman V winter wheat (Triticum aestivum L.) varieties. As a consequence of water withdrawal, there was a decrease in the size of the embryos and the number of A-type starch granules deposited in the endosperm, while the development of aleurone cells and the degradation of the cell layers surrounding the ovule were significantly accelerated in both genotypes. In addition, the number of B-type starch granules per cell was significantly reduced. Drought stress affected the rate of grain filling shortened the grain-filling and ripening period and severely reduced the yield. With respect to the recovery of vegetative tissues, seed set and yield, the drought-tolerant Plainsman V responded significantly better to drought stress than Cappelle Desprez. The reduction in the size of the mature embryos was significantly greater in the sensitive genotype. Compared to Plainsman V, the endosperm cells of Cappelle Desprez accumulated significantly fewer B-type starch granules. In stressed kernels of the tolerant genotype, the accumulation of protein bodies occurred significantly earlier than in the sensitive variety.
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Chiatante, D; Tognetti, R; Scippa, G S; Congiu, T; Baesso, B; Terzaghi, M; Montagnoli, A
2015-07-01
To face summer drought and wildfire in Mediterranean-type ecosystems, plants adopt different strategies that involve considerable rearrangements of biomass allocation and physiological activity. This paper analyses morphological and physiological traits in seedlings of three oak species (Quercus ilex, Quercus trojana and Quercus virgiliana) co-occurring under natural conditions. The aim of this study was to evaluate species-specific characteristics and the response of these oak seedlings to drought stress and fire treatment. Seedlings were kept in a growth chamber that mimicked natural environmental conditions. All three species showed a good degree of tolerance to drought and fire treatments. Differences in specific biomass allocation patterns and physiological traits resulted in phenotypic differences between species. In Q. ilex, drought tolerance depended upon adjustment of the allocation pattern. Q. trojana seedlings undergoing mild to severe drought presented a higher photosystem II (PSII) efficiency than control seedlings. Moreover, Q. trojana showed a very large root system, which corresponded to higher soil area exploitation, and bigger leaf midrib vascular bundles than the other two species. Morphological and physiological performances indicated Q. trojana as the most tolerant to drought and fire. These characteristics contribute to a high recruitment potential of Q. trojana seedlings, which might be the reason for the dominance of this species under natural conditions. Drought increase as a result of climate change is expected to favour Q. trojana, leading to an increase in its spatial distribution.
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AmeriFlux US-SCf Southern California Climate Gradient - Oak/Pine Forest
DOE Office of Scientific and Technical Information (OSTI.GOV)
Goulden, Mike
This is the AmeriFlux version of the carbon flux data for the site US-SCf Southern California Climate Gradient - Oak/Pine Forest. Site Description - Half hourly data are available at https://www.ess.uci.edu/~california/. This site is one of six Southern California Climate Gradient flux towers operated along an elevation gradient (sites are US-SCg, US-SCs, US-SCf, US-SCw, US-SCc, US-SCd). This site is a mixed oak/pine forest. The site experiences episodic severe drought and mortality, and has also experienced occasional logging and wildfire. Drought and mortality was especially severe in the early 2000s.
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Le, Dung Tien; Nishiyama, Rie; Watanabe, Yasuko; Vankova, Radomira; Tanaka, Maho; Seki, Motoaki; Ham, Le Huy; Yamaguchi-Shinozaki, Kazuko; Shinozaki, Kazuo; Tran, Lam-Son Phan
2012-01-01
Cytokinins (CKs) mediate cellular responses to drought stress and targeted control of CK metabolism can be used to develop drought-tolerant plants. Aiming to manipulate CK levels to improve drought tolerance of soybean cultivars through genetic engineering of CK metabolic genes, we surveyed the soybean genome and identified 14 CK biosynthetic (isopentenyltransferase, GmIPT) and 17 CK degradative (CK dehydrogenase, GmCKX) genes. Comparative analyses of GmIPTs and GmCKXs with Arabidopsis counterparts revealed their similar architecture. The average numbers of abiotic stress-inducible cis-elements per promoter were 0.4 and 1.2 for GmIPT and GmCKX genes, respectively, suggesting that upregulation of GmCKXs, thereby reduction of CK levels, maybe the major events under abiotic stresses. Indeed, the expression of 12 GmCKX genes was upregulated by dehydration in R2 roots. Overall, the expressions of soybean CK metabolic genes in various tissues at various stages were highly responsive to drought. CK contents in various organs at the reproductive (R2) stage were also determined under well-watered and drought stress conditions. Although tRNA-type GmIPT genes were highly expressed in soybean, cis-zeatin and its derivatives were found at low concentrations. Moreover, reduction of total CK content in R2 leaves under drought was attributable to the decrease in dihydrozeatin levels, suggesting a role of this molecule in regulating soybean's responses to drought stress. Our systematic analysis of the GmIPT and GmCKX families has provided an insight into CK metabolism in soybean under drought stress and a solid foundation for in-depth characterization and future development of improved drought-tolerant soybean cultivars by manipulation of CK levels via biotechnological approach. PMID:22900018
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Beikircher, Barbara; Mayr, Stefan
2009-06-01
An adequate general drought tolerance and the ability to acclimate to changing hydraulic conditions are important features for long-lived woody plants. In this study, we compared hydraulic safety (water potential at 50% loss of conductivity, Psi(50)), hydraulic efficiency (specific conductivity, k(s)), xylem anatomy (mean tracheid diameter, d(mean), mean hydraulic diameter, d(h), conduit wall thickness, t, conduit wall reinforcement, (t/b)(h)(2)) and stomatal conductance, g(s), of forest plants as well as irrigated and drought-treated garden plants of Ligustrum vulgare L. and Viburnum lantana L. Forest plants of L. vulgare and V. lantana were significantly less resistant to drought-induced cavitation (Psi(50) at -2.82 +/- 0.13 MPa and -2.79 +/- 0.17 MPa) than drought-treated garden plants (- 4.58 +/- 0.26 MPa and -3.57 +/- 0.15 MPa). When previously irrigated garden plants were subjected to drought, a significant decrease in d(mean) and d(h) and an increase in t and (t/b)(h)(2) were observed in L. vulgare. In contrast, in V. lantana conduit diameters increased significantly but no change in t and (t/b)(h)(2) was found. Stomatal closure occurred at similar water potentials (Psi(sc)) in forest plants and drought-treated garden plants, leading to higher safety margins (Psi(sc) - Psi(50)) of the latter (L. vulgare 1.63 MPa and V. lantana 0.43 MPa). These plants also showed higher g(s) at moderate Psi, more abrupt stomatal closure and lower cuticular conductivity. Data indicate that the development of drought-tolerant xylem as well as stomatal regulation play an important role in drought acclimation, whereby structural and physiological responses to drought are species-specific and depend on the plant's hydraulic strategy.
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Bello, Babatunde; Zhang, Xueyan; Liu, Chuanliang; Yang, Zhaoen; Yang, Zuoren; Wang, Qianhua; Zhao, Ge; Li, Fuguang
2014-01-01
The molecular mechanisms of stress tolerance and the use of modern genetics approaches for the improvement of drought stress tolerance have been major focuses of plant molecular biologists. In the present study, we cloned the Gossypium hirsutum sucrose non-fermenting 1-related protein kinase 2 (GhSnRK2) gene and investigated its functions in transgenic Arabidopsis. We further elucidated the function of this gene in transgenic cotton using virus-induced gene silencing (VIGS) techniques. We hypothesized that GhSnRK2 participates in the stress signaling pathway and elucidated its role in enhancing stress tolerance in plants via various stress-related pathways and stress-responsive genes. We determined that the subcellular localization of the GhSnRK2-green fluorescent protein (GFP) was localized in the nuclei and cytoplasm. In contrast to wild-type plants, transgenic plants overexpressing GhSnRK2 exhibited increased tolerance to drought, cold, abscisic acid and salt stresses, suggesting that GhSnRK2 acts as a positive regulator in response to cold and drought stresses. Plants overexpressing GhSnRK2 displayed evidence of reduced water loss, turgor regulation, elevated relative water content, biomass, and proline accumulation. qRT-PCR analysis of GhSnRK2 expression suggested that this gene may function in diverse tissues. Under normal and stress conditions, the expression levels of stress-inducible genes, such as AtRD29A, AtRD29B, AtP5CS1, AtABI3, AtCBF1, and AtABI5, were increased in the GhSnRK2-overexpressing plants compared to the wild-type plants. GhSnRK2 gene silencing alleviated drought tolerance in cotton plants, indicating that VIGS technique can certainly be used as an effective means to examine gene function by knocking down the expression of distinctly expressed genes. The results of this study suggested that the GhSnRK2 gene, when incorporated into Arabidopsis, functions in positive responses to drought stress and in low temperature tolerance. PMID:25393623
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Balfagón, Damián; Zandalinas, Sara I; Baliño, Pablo; Muriach, María; Gómez-Cadenas, Aurelio
2018-06-01
Usually several environmental stresses occur in nature simultaneously causing a unique plant response. However, most of the studies until now have focused in individually-applied abiotic stress conditions. Carrizo citrange (Poncirus trifoliata L. Raf. X Citrus sinensis L. Osb.) and Cleopatra mandarin (Citrus reshni Hort. ex Tan.) are two citrus rootstocks with contrasting tolerance to drought and heat stress and have been used in this work as a model for the study of plant tolerance to the combination of drought and high temperatures. According to our results, leaf integrity and photosynthetic machinery are less affected in Carrizo than in Cleopatra under combined conditions of drought and heat stress. The pattern of accumulation of three proteins (APX, HSP101 and HSP17.6) involved in abiotic stress tolerance shows that they do not accumulate under water stress conditions individually applied. However, contents of APX and HSP101 are higher in Carrizo than in Cleopatra under stress combination whereas HSP17.6 has a similar behavior in both types of plants. This, together with a better stomatal control and a higher APX activity of Carrizo, contributes to the higher tolerance of Carrizo plants to the combination of stresses and point to it as a better rootstock than Cleopatra (traditionally used in areas with scare water supplies) under the predictable future climatic conditions with frequent periods of drought combined with high temperatures. This work also provides the basis for testing the tolerance of different citrus varieties grafted on these rootstocks and growing under different field conditions. Copyright © 2018 Elsevier Masson SAS. All rights reserved.
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Bündig, Christin; Jozefowicz, Anna Maria; Mock, Hans-Peter; Winkelmann, Traud
2016-06-30
Starch potatoes (Solanum tuberosum L.) are of interest for production of starch, ethanol, and biopolymers. Due to the predicted increase in drought periods, the breeding of starch potatoes for drought tolerance is essential. This study aims to elucidate the physiological mechanisms that give rise to drought tolerance. Two genotypes contrasting in drought tolerance were compared. We applied osmotic stress which is a known component of drought stress under in vitro conditions. Shoot tips were harvested after 11days of culture on control medium and medium supplied with 0.2M sorbitol. Their proteomes were analyzed using two-dimensional isoelectric focussing sodium dodecyl sulphate polyacrylamide gel electrophoresis (2D-IEF/SDS-PAGE). Of a total of 679 distinct protein spots, 118 and 20 spots with differential abundance were found in the sensitive and the tolerant genotype, respectively, after the application of stress. Using mass spectrometry, the proteins in 100 differentially abundant spots were identified; a majority of these proteins were from the chloroplast. For the sensitive genotype, an increase in the abundance of proteinase inhibitors and their precursors, changes in stress responsive proteins and an altered RNA/DNA-binding response were observed. The differentially abundant spots of the tolerant genotype comprised one chaperone and one hydrogen peroxide detoxifying protein. Our findings reveal that the two genotypes have different responses to osmotic stress in terms of protein degradation and reactive oxygen species (ROS) scavenging and production. Our data suggest that the tolerant genotype might adjust to the applied stress more quickly. A comparative temporal analysis might provide further insights into these rapid changes and assist in the development of biomarkers. Copyright © 2016 Elsevier B.V. All rights reserved.
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Negi, Sanjana; Tak, Himanshu; Ganapathi, T R
2018-03-01
MusaSNAC1 function in H 2 O 2 mediated stomatal closure and promote drought tolerance by directly binding to CGT[A/G] motif in regulatory region of multiple stress-related genes. Drought is a abiotic stress-condition, causing reduced plant growth and diminished crop yield. Guard cells of the stomata control photosynthesis and transpiration by regulating CO 2 exchange and water loss, thus affecting growth and crop yield. Roles of NAC (NAM, ATAF1/2 and CUC2) protein in regulation of stress-conditions has been well documented however, their control over stomatal aperture is largely unknown. In this study we report a banana NAC protein, MusaSNAC1 which induced stomatal closure by elevating H 2 O 2 content in guard cells during drought stress. Overexpression of MusaSNAC1 in banana resulted in higher number of stomata closure causing reduced water loss and thus elevated drought-tolerance. During drought, expression of GUS (β-glucuronidase) under P MusaSNAC1 was remarkably elevated in guard cells of stomata which correlated with its function as a transcription factor regulating stomatal aperture closing. MusaSNAC1 is a transcriptional activator belonging to SNAC subgroup and its 5'-upstream region contain multiple Dof1 elements as well as stress-associated cis-elements. Moreover, MusaSNAC1 also regulate multiple stress-related genes by binding to core site of NAC-proteins CGT[A/G] in their 5'-upstream region. Results indicated an interesting mechanism of drought tolerance through stomatal closure by H 2 O 2 generation in guard cells, regulated by a NAC-protein in banana.
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Systems biology-based approaches toward understanding drought tolerance in food crops.
Jogaiah, Sudisha; Govind, Sharathchandra Ramsandra; Tran, Lam-Son Phan
2013-03-01
Economically important crops, such as maize, wheat, rice, barley, and other food crops are affected by even small changes in water potential at important growth stages. Developing a comprehensive understanding of host response to drought requires a global view of the complex mechanisms involved. Research on drought tolerance has generally been conducted using discipline-specific approaches. However, plant stress response is complex and interlinked to a point where discipline-specific approaches do not give a complete global analysis of all the interlinked mechanisms. Systems biology perspective is needed to understand genome-scale networks required for building long-lasting drought resistance. Network maps have been constructed by integrating multiple functional genomics data with both model plants, such as Arabidopsis thaliana, Lotus japonicus, and Medicago truncatula, and various food crops, such as rice and soybean. Useful functional genomics data have been obtained from genome-wide comparative transcriptome and proteome analyses of drought responses from different crops. This integrative approach used by many groups has led to identification of commonly regulated signaling pathways and genes following exposure to drought. Combination of functional genomics and systems biology is very useful for comparative analysis of other food crops and has the ability to develop stable food systems worldwide. In addition, studying desiccation tolerance in resurrection plants will unravel how combination of molecular genetic and metabolic processes interacts to produce a resurrection phenotype. Systems biology-based approaches have helped in understanding how these individual factors and mechanisms (biochemical, molecular, and metabolic) "interact" spatially and temporally. Signaling network maps of such interactions are needed that can be used to design better engineering strategies for improving drought tolerance of important crop species.
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Vigani, Gianpiero; Rolli, Eleonora; Marasco, Ramona; Dell'Orto, Marta; Michoud, Grégoire; Soussi, Asma; Raddadi, Noura; Borin, Sara; Sorlini, Claudia; Zocchi, Graziano; Daffonchio, Daniele
2018-05-22
It has been previously shown that the transgenic overexpression of the plant root vacuolar proton pumps H + -ATPase (V-ATPase) and H + -PPase (V-PPase) confer tolerance to drought. Since plant-root endophytic bacteria can also promote drought tolerance, we hypothesize that such promotion can be associated to the enhancement of the host vacuolar proton pumps expression and activity. To test this hypothesis, we selected two endophytic bacteria endowed with an array of in vitro plant growth promoting traits. Their genome sequences confirmed the presence of traits previously shown to confer drought resistance to plants, such as the synthesis of nitric oxide and of organic volatile organic compounds. We used the two strains on pepper (Capsicuum annuum L.) because of its high sensitivity to drought. Under drought conditions, both strains stimulated a larger root system and enhanced the leaves' photosynthetic activity. By testing the expression and activity of the vacuolar proton pumps, H + -ATPase (V-ATPase) and H + -PPase (V-PPase), we found that bacterial colonization enhanced V-PPase only. We conclude that the enhanced expression and activity of V-PPase can be favoured by the colonization of drought-tolerance-inducing bacterial endophytes. This article is protected by copyright. All rights reserved. © 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.
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Gorim, Linda Y; Vandenberg, Albert
2017-01-01
Increasingly unpredictable annual rainfall amounts and distribution patterns have far reaching implications for pulse crop biology. Seedling and whole plant survival will be affected given that water is a key factor in plant photosynthesis and also influences the evolving disease spectrum that affects crops. The wild relatives of cultivated lentil are native to drought prone areas, making them good candidates for the evaluation of drought tolerance traits. We evaluated root and shoot traits of genotypes of cultivated lentil and five wild species grown under two water deficit regimes as well as fully watered conditions over a 13 week period indoors. Plants were grown in sectioned polyvinyl chloride (PVC) tubes containing field soil from the A, B, and C horizons. We found that root distribution into different soil horizons varied among wild lentil genotypes. Secondly, wild lentil genotypes employed diverse strategies such as delayed flowering, reduced transpiration rates, reduced plant height, and deep root systems to either escape, evade or tolerate drought conditions. In some cases, more than one drought strategy was observed within the same genotype. Sequence based classification of wild and cultivated genotypes did not explain patterns of drought response. The environmental conditions at their centers of origin may explain the patterns of drought strategies observed in wild lentils. The production of numerous small seeds by wild lentil genotypes may have implications for yield improvement in lentil breeding programs.
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Evaluation of seven drought tolerant tree species for central California
E.G. McPherson; S. Albers
2014-01-01
Climate change poses challenges for the Southwest, where an already parched region is expected to get hotter and, in its southern half, significantly drier (Garfin et al. 2013). Increased heat and sustained drought will stress water sources and redefine urban landscapes. As landscapes gradually evolve from lush to xeric, tolerance of trees to water-related stress...
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Is the wide distribution of aspen a result of its stress tolerance?
V. J. Lieffers; S. M. Landhausser; E. H. Hogg
2001-01-01
Populus tremuloides is distributed from drought-prone fringes of the Great Plains to extremely cold sites at arctic treeline. To occupy these conditions aspen appears to be more tolerant of stress than the other North American species of the genus Populus. Cold winters, cold soil conditions during the growing season, periodic drought, insect defoliation, and...
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USDA-ARS?s Scientific Manuscript database
This paper describes the isolation of Wheat ABA-responsive mutants (Warm) in Chinese spring background of allohexaploid Triticum aestivum. The plant hormone abscisic acid (ABA) is required for the induction of seed dormancy, the induction of stomatal closure and drought tolerance, and is associated...
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Chalita Sriladda; Roger Kjelgren; Heidi Kratsch; Thomas Monaco; Steven Larson; FenAnn Shen
2014-01-01
Due to limited water supplies, use of drought-tolerant species to conserve water in irrigated urban landscapes is increasingly important in the Intermountain West. The Colorado Plateau endemic shrub Shepherdia rotundifolia Parry is a potential candidate for use in sustainable urban low-water landscapes (LWLs) for its aesthetic and drought-tolerant qualities. However,...
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Eco-physiology of Acer saccharum trees on glade-like sites in central Missouri
Eric J. Rhodenbaugh; Stephen G. Pallardy
1993-01-01
Although sugar maple (Acer saccharum Marsh.) is not considered drought tolerant, it is common on xeric limestone glade-like sites in central Missouri. Acer saccharum on such sites may be a drought-tolerant ecotype or may have access to deep water supply through bedrock cracks. We investigated these possibilities during the 1990...
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USDA-ARS?s Scientific Manuscript database
Wheat breeding has improved drought tolerance over the years. However, our knowledge on drought tolerance in relation to the canopy temperature (CT) and grain yield is limited. A three-season wheat field study ending 2012, 2015, and 2016 was conducted at Bushland, Texas to investigate the relationsh...
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The impact of tillage on Pinto bean cultivar response to drought induced by deficit irrigation
USDA-ARS?s Scientific Manuscript database
Drought stress is a major factor limiting yield of dry bean (Phaseolus vulgaris) and drought tolerant cultivars are being developed. Reducing tillage in row crops has advantages of conserving moisture and increasing water infiltration, and may alter the response of dry bean cultivars to drought stre...
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Asfaw, Asrat; Blair, Matthew W.; Struik, Paul C.
2012-01-01
Many of the world’s common bean (Phaseolus vulgaris L.) growing regions are prone to either intermittent or terminal drought stress, making drought the primary cause of yield loss under farmers’ field conditions. Improved photosynthate acquisition, accumulation, and then remobilization have been observed as important mechanisms for adaptation to drought stress. The objective of this study was to tag quantitative trait loci (QTL) for photosynthate acquisition, accumulation, and remobilization to grain by using a recombinant inbred line population developed from the Mesoamerican intragenepool cross of drought-susceptible DOR364 and drought-tolerant BAT477 grown under eight environments differing in drought stress across two continents: Africa and South America. The recombinant inbred line population expressed quantitative variation and transgressive segregation for 11 traits associated with drought tolerance. QTL were detected by both a mixed multienvironment model and by composite interval mapping for each environment using a linkage map constructed with 165 genetic markers that covered 11 linkage groups of the common bean genome. In the multienvironment, mixed model, nine QTL were detected for 10 drought stress tolerance mechanism traits found on six of the 11 linkage groups. Significant QTL × environment interaction was observed for six of the nine QTL. QTL × environment interaction was of the cross-over type for three of the six significant QTL with contrasting effect of the parental alleles across different environments. In the composite interval mapping, we found 69 QTL in total. The majority of these were found for Palmira (47) or Awassa (18), with fewer in Malawi (4). Phenotypic variation explained by QTL in single environments ranged up to 37%, and the most consistent QTL were for Soil Plant Analysis Development (SPAD) leaf chlorophyll reading and pod partitioning traits. QTL alignment between the two detection methods showed that yield QTL on b08 and stem carbohydrate QTL on b05 were most consistent between the multilocation model and the single environment detection. Our results indicate the relevance of QTL detection in the sites in which bean breeding will be undertaken and the importance of photosynthate accumulation as a trait for common bean drought tolerance. PMID:22670228
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Asfaw, Asrat; Blair, Matthew W; Struik, Paul C
2012-05-01
Many of the world's common bean (Phaseolus vulgaris L.) growing regions are prone to either intermittent or terminal drought stress, making drought the primary cause of yield loss under farmers' field conditions. Improved photosynthate acquisition, accumulation, and then remobilization have been observed as important mechanisms for adaptation to drought stress. The objective of this study was to tag quantitative trait loci (QTL) for photosynthate acquisition, accumulation, and remobilization to grain by using a recombinant inbred line population developed from the Mesoamerican intragenepool cross of drought-susceptible DOR364 and drought-tolerant BAT477 grown under eight environments differing in drought stress across two continents: Africa and South America. The recombinant inbred line population expressed quantitative variation and transgressive segregation for 11 traits associated with drought tolerance. QTL were detected by both a mixed multienvironment model and by composite interval mapping for each environment using a linkage map constructed with 165 genetic markers that covered 11 linkage groups of the common bean genome. In the multienvironment, mixed model, nine QTL were detected for 10 drought stress tolerance mechanism traits found on six of the 11 linkage groups. Significant QTL × environment interaction was observed for six of the nine QTL. QTL × environment interaction was of the cross-over type for three of the six significant QTL with contrasting effect of the parental alleles across different environments. In the composite interval mapping, we found 69 QTL in total. The majority of these were found for Palmira (47) or Awassa (18), with fewer in Malawi (4). Phenotypic variation explained by QTL in single environments ranged up to 37%, and the most consistent QTL were for Soil Plant Analysis Development (SPAD) leaf chlorophyll reading and pod partitioning traits. QTL alignment between the two detection methods showed that yield QTL on b08 and stem carbohydrate QTL on b05 were most consistent between the multilocation model and the single environment detection. Our results indicate the relevance of QTL detection in the sites in which bean breeding will be undertaken and the importance of photosynthate accumulation as a trait for common bean drought tolerance.
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Lázaro-Nogal, Ana; Forner, Alicia; Traveset, Anna; Valladares, Fernando
2013-12-01
Plants have evolved different strategies to cope with drought, involving alternative ecophysiologies and different levels of plasticity. These strategies are critical for species of limited distribution, which are especially vulnerable to the current rates of rapid environmental change. The aim of this study was to assess the water strategy of two species with limited distribution, Cneorum tricoccon L. and Rhamnus ludovici-salvatoris Chodat., and evaluate their interpopulation variability along an aridity gradient to estimate their vulnerability to a drier climate. We measured different ecophysiological traits influenced by drought--stomatal conductance, maximum photochemical efficiency of photosynthesis II, carbon isotope ratio and chlorophyll concentration--in two climatically contrasting years, before and during summer drought. Both species were vulnerable to drought at the aridity limit of the gradient, but showed contrasting water strategies: while C. tricoccon was consistent in its water conservation strategy across the aridity gradient, R. ludovici-salvatoris was not, displaying higher and more variable stomatal conductances and being able to increase water-use efficiency at the most xeric sites. Changes in length and intensity of drought events may favor one species' strategy to the detriment of the other: C. tricoccon is more vulnerable to chronic and prolonged droughts, whereas short but acute droughts might have a stronger effect on R. ludovici-salvatoris. In those communities where these two species coexist, such different strategies might lead to changes in community structure under climate change scenarios, with unknown cascade effects on ecosystem functioning.
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Martin-Stpaul, Nicolas K; Limousin, Jean-Marc; Vogt-Schilb, Hélène; Rodríguez-Calcerrada, Jesus; Rambal, Serge; Longepierre, Damien; Misson, Laurent
2013-08-01
Like many midlatitude ecosystems, Mediterranean forests will suffer longer and more intense droughts with the ongoing climate change. The responses to drought in long-lived trees differ depending on the time scale considered, and short-term responses are currently better understood than longer term acclimation. We assessed the temporal changes in trees facing a chronic reduction in water availability by comparing leaf-scale physiological traits, branch-scale hydraulic traits, and stand-scale biomass partitioning in the evergreen Quercus ilex across a regional precipitation gradient (long-term changes) and in a partial throughfall exclusion experiment (TEE, medium term changes). At the leaf scale, gas exchange, mass per unit area and nitrogen concentration showed homeostatic responses to drought as they did not change among the sites of the precipitation gradient or in the experimental treatments of the TEE. A similar homeostatic response was observed for the xylem vulnerability to cavitation at the branch scale. In contrast, the ratio of leaf area over sapwood area (LA/SA) in young branches exhibited a transient response to drought because it decreased in response to the TEE the first 4 years of treatment, but did not change among the sites of the gradient. At the stand scale, leaf area index (LAI) decreased, and the ratios of stem SA to LAI and of fine root area to LAI both increased in trees subjected to throughfall exclusion and from the wettest to the driest site of the gradient. Taken together, these results suggest that acclimation to chronic drought in long-lived Q. ilex is mediated by changes in hydraulic allometry that shift progressively from low (branch) to high (stand) organizational levels, and act to maintain the leaf water potential within the range of xylem hydraulic function and leaf photosynthetic assimilation. © 2013 John Wiley & Sons Ltd.
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Timmusk, Salme; Abd El-Daim, Islam A.; Copolovici, Lucian; Tanilas, Triin; Kännaste, Astrid; Behers, Lawrence; Nevo, Eviatar; Seisenbaeva, Gulaim; Stenström, Elna; Niinemets, Ülo
2014-01-01
Water is the key resource limiting world agricultural production. Although an impressive number of research reports have been published on plant drought tolerance enhancement via genetic modifications during the last few years, progress has been slower than expected. We suggest a feasible alternative strategy by application of rhizospheric bacteria coevolved with plant roots in harsh environments over millions of years, and harboring adaptive traits improving plant fitness under biotic and abiotic stresses. We show the effect of bacterial priming on wheat drought stress tolerance enhancement, resulting in up to 78% greater plant biomass and five-fold higher survivorship under severe drought. We monitored emissions of seven stress-related volatiles from bacterially-primed drought-stressed wheat seedlings, and demonstrated that three of these volatiles are likely promising candidates for a rapid non-invasive technique to assess crop drought stress and its mitigation in early phases of stress development. We conclude that gauging stress by elicited volatiles provides an effectual platform for rapid screening of potent bacterial strains and that priming with isolates of rhizospheric bacteria from harsh environments is a promising, novel way to improve plant water use efficiency. These new advancements importantly contribute towards solving food security issues in changing climates. PMID:24811199
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Legume abundance along successional and rainfall gradients in Neotropical forests.
Gei, Maga; Rozendaal, Danaë M A; Poorter, Lourens; Bongers, Frans; Sprent, Janet I; Garner, Mira D; Aide, T Mitchell; Andrade, José Luis; Balvanera, Patricia; Becknell, Justin M; Brancalion, Pedro H S; Cabral, George A L; César, Ricardo Gomes; Chazdon, Robin L; Cole, Rebecca J; Colletta, Gabriel Dalla; de Jong, Ben; Denslow, Julie S; Dent, Daisy H; DeWalt, Saara J; Dupuy, Juan Manuel; Durán, Sandra M; do Espírito Santo, Mário Marcos; Fernandes, G Wilson; Nunes, Yule Roberta Ferreira; Finegan, Bryan; Moser, Vanessa Granda; Hall, Jefferson S; Hernández-Stefanoni, José Luis; Junqueira, André B; Kennard, Deborah; Lebrija-Trejos, Edwin; Letcher, Susan G; Lohbeck, Madelon; Marín-Spiotta, Erika; Martínez-Ramos, Miguel; Meave, Jorge A; Menge, Duncan N L; Mora, Francisco; Muñoz, Rodrigo; Muscarella, Robert; Ochoa-Gaona, Susana; Orihuela-Belmonte, Edith; Ostertag, Rebecca; Peña-Claros, Marielos; Pérez-García, Eduardo A; Piotto, Daniel; Reich, Peter B; Reyes-García, Casandra; Rodríguez-Velázquez, Jorge; Romero-Pérez, I Eunice; Sanaphre-Villanueva, Lucía; Sanchez-Azofeifa, Arturo; Schwartz, Naomi B; de Almeida, Arlete Silva; Almeida-Cortez, Jarcilene S; Silver, Whendee; de Souza Moreno, Vanessa; Sullivan, Benjamin W; Swenson, Nathan G; Uriarte, Maria; van Breugel, Michiel; van der Wal, Hans; Veloso, Maria das Dores Magalhães; Vester, Hans F M; Vieira, Ima Célia Guimarães; Zimmerman, Jess K; Powers, Jennifer S
2018-05-28
The nutrient demands of regrowing tropical forests are partly satisfied by nitrogen-fixing legume trees, but our understanding of the abundance of those species is biased towards wet tropical regions. Here we show how the abundance of Leguminosae is affected by both recovery from disturbance and large-scale rainfall gradients through a synthesis of forest inventory plots from a network of 42 Neotropical forest chronosequences. During the first three decades of natural forest regeneration, legume basal area is twice as high in dry compared with wet secondary forests. The tremendous ecological success of legumes in recently disturbed, water-limited forests is likely to be related to both their reduced leaflet size and ability to fix N 2 , which together enhance legume drought tolerance and water-use efficiency. Earth system models should incorporate these large-scale successional and climatic patterns of legume dominance to provide more accurate estimates of the maximum potential for natural nitrogen fixation across tropical forests.
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Differentiation in the water-use strategies among oak species from central Mexico.
Aguilar-Romero, Rafael; Pineda-Garcia, Fernando; Paz, Horacio; González-Rodríguez, Antonio; Oyama, Ken
2017-07-01
Oak species (Fagaceae: Quercus) differ in their distribution at the landscape scale, specializing to a certain portion of environmental gradients. This suggests that functional differentiation favors habitat partitioning among closely related species. To elucidate the mechanisms of species coexistence in oak forests, we explored patterns of interspecific variation in functional traits involved in water-use strategies. We tested the hypothesis that oak species segregate along key trade-offs between xylem hydraulic efficiency and safety, and between hydraulic safety and drought avoidance capacity, leading to species niche partitioning across a gradient of aridity. To do so, we quantified biophysical and physiological traits in four red and five white oak species (sections Lobatae and Quercus, respectively) across an aridity gradient in central Mexico. We also explored the trade-offs guiding species differentiation, particularly between the drought tolerance versus water acquisition capacity, and determined whether the water-use strategy was associated with the portion of the environmental gradient that the species occupy. In a trait-by-trait analysis, we detected differences between white and red oak species. However, a larger part of the variation was explained at the species rather than at the section level. We detected two primary axes of trait covariation. The first exhibited differences between species with dense tissues and species with soft tissues (the tissue construction cost axis); however, the oak sections did not constitute separate groups, while the second suggested a trade-off between xylem resistance to cavitation and tree deciduousness. As expected, the water-use strategies of the species were related to the environment; oak species from arid areas had more deciduousness and a higher instantaneous water-use efficiency. In contrast, their humid counterparts had less deciduousness and had a xylem that was more resistant to embolisms. Altogether, these results suggest that aridity filters closely related species, resulting in habitat partitioning and niche divergence. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
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Pests vs. drought as determinants of plant distribution along a tropical rainfall gradient.
Brenes-Arguedas, Tania; Coley, Phyllis D; Kursar, Thomas A
2009-07-01
Understanding the mechanisms that shape the distribution of organisms can help explain patterns of local and regional biodiversity and predict the susceptibility of communities to environmental change. In the species-rich tropics, a gradient in rainfall between wet evergreen and dry seasonal forests correlates with turnover of plant species. The strength of the dry season has previously been shown to correlate with species composition. Herbivores and pathogens (pests) have also been hypothesized to be important drivers of plant distribution, although empirical evidence is lacking. In this study we experimentally tested the existence of a gradient in pest pressure across a rainfall gradient in the Isthmus of Panama and measured the influence of pests relative to drought on species turnover. We established two common gardens on the dry and wet sides of the Isthmus using seedlings from 24 plant species with contrasting distributions along the Isthmus. By experimentally manipulating water availability and insect herbivore access, we showed that pests are not as strong a determinant of plant distributions as is seasonal drought. Seasonal drought in the dry site excluded wet-distribution species by significantly increasing their seedling mortality. Pathogen mortality and insect herbivore damage were both higher in the wet site, supporting the existence of a gradient in pest pressure. However, contrary to predictions, we found little evidence that dry-distribution species suffered significantly more pest attack than wet-distribution species. Instead, we hypothesize that dry-distribution species are limited from colonizing wetter forests by their inherently slower growth rates imposed by drought adaptations. We conclude that mechanisms limiting the recruitment of dry-distribution species in wet forests are not nearly as strong as those limiting wet-distribution species from dry forests.
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Mishra, Neelam; Sun, Li; Zhu, Xunlu; Smith, Jennifer; Prakash Srivastava, Anurag; Yang, Xiaojie; Pehlivan, Necla; Esmaeili, Nardana; Luo, Hong; Shen, Guoxin; Jones, Don; Auld, Dick; Burke, John
2017-01-01
The Arabidopsis SUMO E3 ligase gene AtSIZ1 plays important roles in plant response to abiotic stresses as loss of function in AtSIZ1 leads to increased sensitivity to drought, heat and salt stresses. Overexpression of the AtSIZ1 rice homolog, OsSIZ1, leads to increased heat and drought tolerance in bentgrass, suggesting that the function of the E3 ligase SIZ1 is highly conserved in plants and it plays a critical role in abiotic stress responses. To test the possibility that the SUMO E3 ligase could be used to engineer drought- and heat-tolerant crops, the rice gene OsSIZ1 was overexpressed in cotton. We report here that overexpression of OsSIZ1 in cotton results in higher net photosynthesis and better growth than wild-type cotton under drought and thermal stresses in growth chamber and greenhouse conditions. Additionally, this tolerance to abiotic stresses was correlated with higher fiber yield in both controlled-environment and field trials carried out under reduced irrigation and rainfed conditions. These results suggest that OsSIZ1 is a viable candidate gene to improve crop yields under water-limited and rainfed agricultural production systems. PMID:28340002
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Zhu, Mingku; Meng, Xiaoqing; Cai, Jing; Li, Ge; Dong, Tingting; Li, Zongyun
2018-05-08
Basic region/leucine zipper (bZIP) transcription factors perform as crucial regulators in ABA-mediated stress response in plants. Nevertheless, the functions for most bZIP family members in tomato remain to be deciphered. Here we examined the functional characterization of SlbZIP1 under salt and drought stresses in tomato. Silencing of SlbZIP1 in tomato resulted in reduced expression of multiple ABA biosynthesis- and signal transduction-related genes in transgenic plants. In stress assays, SlbZIP1-RNAi transgenic plants exhibited reduced tolerance to salt and drought stresses compared with WT plants, as are evaluated by multiple physiological parameters associated with stress responses, such as decreased ABA, chlorophyll contents and CAT activity, and increased MDA content. In addition, RNA-seq analysis of transgenic plants revealed that the transcription levels of multiple genes encoding defense proteins related to responses to abiotic stress (e.g. endochitinase, peroxidases, and lipid transfer proteins) and biotic stress (e.g. pathogenesis-related proteins) were downregulated in SlbZIP1-RNAi plants, suggesting that SlbZIP1 plays a role in regulating the genes related to biotic and abiotic stress response. Collectively, the data suggest that SlbZIP1 exerts an essential role in salt and drought stress tolerance through modulating an ABA-mediated pathway, and SlbZIP1 may hold potential applications in the engineering of salt- and drought-tolerant tomato cultivars.
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Characterization of Transcription Factor Gene OsDRAP1 Conferring Drought Tolerance in Rice
Huang, Liyu; Wang, Yinxiao; Wang, Wensheng; Zhao, Xiuqin; Qin, Qiao; Sun, Fan; Hu, Fengyi; Zhao, Yan; Li, Zichao; Fu, Binying; Li, Zhikang
2018-01-01
HIGHLIGHTS Overexpressing and RNA interfering OsDRAP1 transgenic rice plants exhibited significantly improved and reduced drought tolerance, but accompanied with negative effects on development and yield. The dehydration responsive element binding (DREBs) genes are important transcription factors which play a crucial role in plant abiotic stress tolerances. In this study, we functionally characterized a DREB2-like gene, OsDRAP1 conferring drought tolerance (DT) in rice. OsDRAP1, containing many cis-elements in its promoter region, was expressed in all organs (mainly expressed in vascular tissues) of rice, and induced by a variety of environmental stresses and plant hormones. Overexpressing OsDRAP1 transgenic plants exhibited significantly improved DT; while OsDRAP1 RNA interfering plants exhibited significantly reduced DT which also accompanied with significant negative effects on development and yield. Overexpression of OsDRAP1 has a positive impact on maintaining water balance, redox homeostasis and vascular development in transgenic rice plants under drought stress. OsDRAP1 interacted with many genes/proteins and could activate many downstream DT related genes, including important transcription factors such as OsCBSX3 to response drought stress, indicating the OsDRAP1-mediated pathways for DT involve complex genes networks. All these results provide a basis for further complete understanding of the OsDRAP1 mediated gene networks and their related phenotypic effects. PMID:29449862
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Sinha, Pallavi; Pazhamala, Lekha T.; Singh, Vikas K.; Saxena, Rachit K.; Krishnamurthy, L.; Azam, Sarwar; Khan, Aamir W.; Varshney, Rajeev K.
2016-01-01
Pigeonpea is a resilient crop, which is relatively more drought tolerant than many other legume crops. To understand the molecular mechanisms of this unique feature of pigeonpea, 51 genes were selected using the Hidden Markov Models (HMM) those codes for proteins having close similarity to universal stress protein domain. Validation of these genes was conducted on three pigeonpea genotypes (ICPL 151, ICPL 8755, and ICPL 227) having different levels of drought tolerance. Gene expression analysis using qRT-PCR revealed 6, 8, and 18 genes to be ≥2-fold differentially expressed in ICPL 151, ICPL 8755, and ICPL 227, respectively. A total of 10 differentially expressed genes showed ≥2-fold up-regulation in the more drought tolerant genotype, which encoded four different classes of proteins. These include plant U-box protein (four genes), universal stress protein A-like protein (four genes), cation/H(+) antiporter protein (one gene) and an uncharacterized protein (one gene). Genes C.cajan_29830 and C.cajan_33874 belonging to uspA, were found significantly expressed in all the three genotypes with ≥2-fold expression variations. Expression profiling of these two genes on the four other legume crops revealed their specific role in pigeonpea. Therefore, these genes seem to be promising candidates for conferring drought tolerance specifically to pigeonpea. PMID:26779199
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Reduced Lateral Root Branching Density Improves Drought Tolerance in Maize1[OPEN
Zhan, Ai; Schneider, Hannah
2015-01-01
An emerging paradigm is that root traits that reduce the metabolic costs of soil exploration improve the acquisition of limiting soil resources. Here, we test the hypothesis that reduced lateral root branching density will improve drought tolerance in maize (Zea mays) by reducing the metabolic costs of soil exploration, permitting greater axial root elongation, greater rooting depth, and thereby greater water acquisition from drying soil. Maize recombinant inbred lines with contrasting lateral root number and length (few but long [FL] and many but short [MS]) were grown under water stress in greenhouse mesocosms, in field rainout shelters, and in a second field environment with natural drought. Under water stress in mesocosms, lines with the FL phenotype had substantially less lateral root respiration per unit of axial root length, deeper rooting, greater leaf relative water content, greater stomatal conductance, and 50% greater shoot biomass than lines with the MS phenotype. Under water stress in the two field sites, lines with the FL phenotype had deeper rooting, much lighter stem water isotopic signature, signifying deeper water capture, 51% to 67% greater shoot biomass at flowering, and 144% greater yield than lines with the MS phenotype. These results entirely support the hypothesis that reduced lateral root branching density improves drought tolerance. The FL lateral root phenotype merits consideration as a selection target to improve the drought tolerance of maize and possibly other cereal crops. PMID:26077764
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Peirone, Laura S.; Pereyra Irujo, Gustavo A.; Bolton, Alejandro; Erreguerena, Ignacio; Aguirrezábal, Luis A. N.
2018-01-01
Conventional field phenotyping for drought tolerance, the most important factor limiting yield at a global scale, is labor-intensive and time-consuming. Automated greenhouse platforms can increase the precision and throughput of plant phenotyping and contribute to a faster release of drought tolerant varieties. The aim of this work was to establish a framework of analysis to identify early traits which could be efficiently measured in a greenhouse automated phenotyping platform, for predicting the drought tolerance of field grown soybean genotypes. A group of genotypes was evaluated, which showed variation in their drought susceptibility index (DSI) for final biomass and leaf area. A large number of traits were measured before and after the onset of a water deficit treatment, which were analyzed under several criteria: the significance of the regression with the DSI, phenotyping cost, earliness, and repeatability. The most efficient trait was found to be transpiration efficiency measured at 13 days after emergence. This trait was further tested in a second experiment with different water deficit intensities, and validated using a different set of genotypes against field data from a trial network in a third experiment. The framework applied in this work for assessing traits under different criteria could be helpful for selecting those most efficient for automated phenotyping. PMID:29774042
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Coleto, I.; Pineda, M.; Rodiño, A. P.; De Ron, A. M.; Alamillo, J. M.
2014-01-01
Background and Aims Drought is the principal constraint on world production of legume crops. There is considerable variability among genotypes in sensitivity of nitrogen fixation to drought, which has been related to accumulation of ureides in soybean. The aim of this study was to search for genotypic differences in drought sensitivity and ureide accumulation in common bean (Phaseolus vulgaris) germplasm that may be useful in the improvement of tolerance to water deficit in common bean. Methods Changes in response to water deficit of nitrogen fixation rates, ureide content and the expression and activity of key enzymes for ureide metabolism were measured in four P. vulgaris genotypes differing in drought tolerance. Key Results A variable degree of drought-induced nitrogen fixation inhibition was found among the bean genotypes. In addition to inhibition of nitrogen fixation, there was accumulation of ureides in stems and leaves of sensitive and tolerant genotypes, although this was higher in the leaves of the most sensitive ones. In contrast, there was no accumulation of ureides in the nodules or roots of stressed plants. In addition, the level of ureides in the most sensitive genotype increased after inhibition of nitrogen fixation, suggesting that ureides originate in vegetative tissues as a response to water stress, probably mediated by the induction of allantoinase. Conclusions Variability of drought-induced inhibition of nitrogen fixation among the P. vulgaris genotypes was accompanied by subsequent accumulation of ureides in stems and leaves, but not in nodules. The results indicate that shoot ureide accumulation after prolonged exposure to drought could not be the cause of inhibition of nitrogen fixation, as has been suggested in soybean. Instead, ureides seem to be produced as part of a general response to stress, and therefore higher accumulation might correspond to higher sensitivity to the stressful conditions. PMID:24638821
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Coleto, I; Pineda, M; Rodiño, A P; De Ron, A M; Alamillo, J M
2014-05-01
Drought is the principal constraint on world production of legume crops. There is considerable variability among genotypes in sensitivity of nitrogen fixation to drought, which has been related to accumulation of ureides in soybean. The aim of this study was to search for genotypic differences in drought sensitivity and ureide accumulation in common bean (Phaseolus vulgaris) germplasm that may be useful in the improvement of tolerance to water deficit in common bean. Changes in response to water deficit of nitrogen fixation rates, ureide content and the expression and activity of key enzymes for ureide metabolism were measured in four P. vulgaris genotypes differing in drought tolerance. A variable degree of drought-induced nitrogen fixation inhibition was found among the bean genotypes. In addition to inhibition of nitrogen fixation, there was accumulation of ureides in stems and leaves of sensitive and tolerant genotypes, although this was higher in the leaves of the most sensitive ones. In contrast, there was no accumulation of ureides in the nodules or roots of stressed plants. In addition, the level of ureides in the most sensitive genotype increased after inhibition of nitrogen fixation, suggesting that ureides originate in vegetative tissues as a response to water stress, probably mediated by the induction of allantoinase. Variability of drought-induced inhibition of nitrogen fixation among the P. vulgaris genotypes was accompanied by subsequent accumulation of ureides in stems and leaves, but not in nodules. The results indicate that shoot ureide accumulation after prolonged exposure to drought could not be the cause of inhibition of nitrogen fixation, as has been suggested in soybean. Instead, ureides seem to be produced as part of a general response to stress, and therefore higher accumulation might correspond to higher sensitivity to the stressful conditions.
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Qiao, Lixian; Sun, Shimeng; Hu, Xiaohui; Chen, Jing; Wang, Jingshan
2015-01-01
In order to enlarge the potential resources of drought-tolerant peanuts, we conducted in vitro mutagenesis with Pingyangmycin (PYM) as the mutagen as well as directed screening on a medium supplemented with Hydroxyproline (HYP). After being extracted from mature seeds (cv. Huayu 20), the embryonic leaflets were cultured on somatic embryogenesis-induction medium with 4 mg/L PYM and the generated embryos were successively transferred to a germination medium with 4 and then 8 mmol/L HYP to screen HYP-tolerant plantlets. After that, these plantlets were grafted and transplanted to the experimental field. In the next generation, all seeds were sown in the field, and phenotype variation and trait segregation can be observed in most of the offspring (M2 generation). The M3 generation individuals were subjected to drought stress at the seedling stages. The activities of SOD and POD were substantially increased in eight offspring of 11 HYP-tolerant, regenerated plants than in their mutagenic parents. To determine the correlation between mutant phenotypes and genomic modification, we carried out a comparison of the DNA polymorphisms between the mutagenic parents and 13 M3 generation individuals from different HYP-tolerant, regenerated plants with SSR primers. Results showed that most mutants and parent plants had signs of polymorphisms. Under drought stress, some M3 generation individuals of 10 original HYP-tolerant, regenerated plants produced more pods than the mutagenic parent; twenty individuals among them produced >60 g pods/plant. M4-generation seeds were tested for quality characteristics by Near Infrared Spectroscopy (NIS) and nine individuals with higher protein content (>30%) and 21 individuals with higher oil content (>58%) were screened. We concluded that the use of PYM-based in vitro mutagenesis in combination with directed screening with HYP is effective for the creation of potential drought-tolerant mutants of peanut. PMID:25826431
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Kong, Xiangzhu; Zhou, Shumei; Yin, Suhong; Zhao, Zhongxian; Han, Yangyang; Wang, Wei
2016-01-01
E3 ligase plays an important role in the response to many environment stresses in plants. In our previous study, constitutive overexpression of an F-box protein gene TaFBA1 driven by 35S promoter improved the drought tolerance in transgenic tobacco plants, but the growth and development in transgenic plants was altered in normal conditions. In this study, we used stress-inducible promoter RD29A instead of 35S promoter, as a results, the stress-inducible transgenic tobacco plants exhibit a similar phenotype with wild type (WT) plants. However, the drought tolerance of the transgenic plants with stress-inducible expressed TaFBA1 was enhanced. The improved drought tolerance of transgenic plants was indicated by their higher seed germination rate and survival rate, greater biomass and photosynthesis than those of WT under water stress, which may be related to their greater water retention capability and osmotic adjustment. Moreover, the transgenic plants accumulated less reactive oxygen species, kept lower MDA content and membrane leakage under water stress, which may be related to their higher levels of antioxidant enzyme activity and upregulated gene expression of some antioxidant enzymes. These results suggest that stress induced expression of TaFBA1 confers drought tolerance via the improved water retention and antioxidative compete ability. Meanwhile, this stress-inducible expression strategy by RD29A promoter can minimize the unexpectable effects by 35S constitutive promoter on phenotypes of the transgenic plants.
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Identification of novel drought-tolerant-associated SNPs in common bean (Phaseolus vulgaris)
Villordo-Pineda, Emiliano; González-Chavira, Mario M.; Giraldo-Carbajo, Patricia; Acosta-Gallegos, Jorge A.; Caballero-Pérez, Juan
2015-01-01
Common bean (Phaseolus vulgaris L.) is a leguminous in high demand for human nutrition and a very important agricultural product. Production of common bean is constrained by environmental stresses such as drought. Although conventional plant selection has been used to increase production yield and stress tolerance, drought tolerance selection based on phenotype is complicated by associated physiological, anatomical, cellular, biochemical, and molecular changes. These changes are modulated by differential gene expression. A common method to identify genes associated with phenotypes of interest is the characterization of Single Nucleotide Polymorphims (SNPs) to link them to specific functions. In this work, we selected two drought-tolerant parental lines from Mesoamerica, Pinto Villa, and Pinto Saltillo. The parental lines were used to generate a population of 282 families (F3:5) and characterized by 169 SNPs. We associated the segregation of the molecular markers in our population with phenotypes including flowering time, physiological maturity, reproductive period, plant, seed and total biomass, reuse index, seed yield, weight of 100 seeds, and harvest index in three cultivation cycles. We observed 83 SNPs with significant association (p < 0.0003 after Bonferroni correction) with our quantified phenotypes. Phenotypes most associated were days to flowering and seed biomass with 58 and 44 associated SNPs, respectively. Thirty-seven out of the 83 SNPs were annotated to a gene with a potential function related to drought tolerance or relevant molecular/biochemical functions. Some SNPs such as SNP28 and SNP128 are related to starch biosynthesis, a common osmotic protector; and SNP18 is related to proline biosynthesis, another well-known osmotic protector. PMID:26257755
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Identification of novel drought-tolerant-associated SNPs in common bean (Phaseolus vulgaris).
Villordo-Pineda, Emiliano; González-Chavira, Mario M; Giraldo-Carbajo, Patricia; Acosta-Gallegos, Jorge A; Caballero-Pérez, Juan
2015-01-01
Common bean (Phaseolus vulgaris L.) is a leguminous in high demand for human nutrition and a very important agricultural product. Production of common bean is constrained by environmental stresses such as drought. Although conventional plant selection has been used to increase production yield and stress tolerance, drought tolerance selection based on phenotype is complicated by associated physiological, anatomical, cellular, biochemical, and molecular changes. These changes are modulated by differential gene expression. A common method to identify genes associated with phenotypes of interest is the characterization of Single Nucleotide Polymorphims (SNPs) to link them to specific functions. In this work, we selected two drought-tolerant parental lines from Mesoamerica, Pinto Villa, and Pinto Saltillo. The parental lines were used to generate a population of 282 families (F3:5) and characterized by 169 SNPs. We associated the segregation of the molecular markers in our population with phenotypes including flowering time, physiological maturity, reproductive period, plant, seed and total biomass, reuse index, seed yield, weight of 100 seeds, and harvest index in three cultivation cycles. We observed 83 SNPs with significant association (p < 0.0003 after Bonferroni correction) with our quantified phenotypes. Phenotypes most associated were days to flowering and seed biomass with 58 and 44 associated SNPs, respectively. Thirty-seven out of the 83 SNPs were annotated to a gene with a potential function related to drought tolerance or relevant molecular/biochemical functions. Some SNPs such as SNP28 and SNP128 are related to starch biosynthesis, a common osmotic protector; and SNP18 is related to proline biosynthesis, another well-known osmotic protector.
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Gibberellin Deficiency Confers Both Lodging and Drought Tolerance in Small Cereals
Plaza-Wüthrich, Sonia; Blösch, Regula; Rindisbacher, Abiel; Cannarozzi, Gina; Tadele, Zerihun
2016-01-01
Tef [Eragrostis tef (Zucc.) Trotter] and finger millet [Eleusine coracana Gaertn] are staple cereal crops in Africa and Asia with several desirable agronomic and nutritional properties. Tef is becoming a life-style crop as it is gluten-free while finger millet has a low glycemic index which makes it an ideal food for diabetic patients. However, both tef and finger millet have extremely low grain yields mainly due to moisture scarcity and susceptibility of the plants to lodging. In this study, the effects of gibberellic acid (GA) inhibitors particularly paclobutrazol (PBZ) on diverse physiological and yield-related parameters were investigated and compared to GA mutants in rice (Oryza sativa L.). The application of PBZ to tef and finger millet significantly reduced the plant height and increased lodging tolerance. Remarkably, PBZ also enhanced the tolerance of both tef and finger millet to moisture deficit. Under moisture scarcity, tef plants treated with PBZ did not exhibit drought-related symptoms and their stomatal conductance was unaltered, leading to higher shoot biomass and grain yield. Semi-dwarf rice mutants altered in GA biosynthesis, were also shown to have improved tolerance to dehydration. The combination of traits (drought tolerance, lodging tolerance and increased yield) that we found in plants with altered GA pathway is of importance to breeders who would otherwise rely on extensive crossing to introgress each trait individually. The key role played by PBZ in the tolerance to both lodging and drought calls for further studies using mutants in the GA biosynthesis pathway in order to obtain candidate lines which can be incorporated into crop-breeding programs to create lodging tolerant and climate-smart crops. PMID:27242844
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Wu, Dandan; Sun, Yinghao; Wang, Hongfei; Shi, He; Su, Mingxing; Shan, Hongyan; Li, Tongtong; Li, Qiuli
2018-07-01
NAC (NAM, ATAF1/2 and CUC) transcription factors play an important role in resisting abiotic stress in plants. In this study, a novel NAC gene, designated SlNAC8 from Suaeda liaotungensis K. was characterized. SlNAC8 protein is localized in the nucleus, and the yeast one-hybrid screening showed that it contains an activation domain in its C-terminus and functions as a transcriptional activator. Gene expression analysis revealed that it is induced by drought and salt stress. Arabidopsis plants overexpressing SlNAC8 demonstrated enhanced tolerance to drought and salt stress, showing significant advantages in seed germination, root growth, shoot growth, and survival rate compared with controls. Moreover, transgenic plants had a significantly higher proline concentration, antioxidant enzyme activity (superoxide dismutase, peroxidase, and catalase), and level of chlorophyll fluorescence than wild-type, and a significantly lower malondialdehyde concentration and electrolyte leakage under drought and salt stress. The overexpression of SlNAC8 in transgenic plants also enhanced the expression of stress-responsive genes such as RD20, GSTF6, COR47, RD29A, RD29B, and NYC1. In summary, SlNAC8, as a transcription factor, may change the physiological-biochemical characteristic of plants by regulating the expression of stress-responsive genes and enhance the drought and salt stress tolerance of plants. SlNAC8 can be utilized for developing drought and salinity tolerance in crop plants through genetic engineering. Copyright © 2018 Elsevier B.V. All rights reserved.
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USDA-ARS?s Scientific Manuscript database
The impact of drought stress on sorghum yield does not only depend on the intensity and timing of drought, but as well on the developmental stage of the crop. One of the limitations in breeding for pre-and/or postflowering drought stress resistance in sorghum is the fewer availability of diverse gen...
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USDA-ARS?s Scientific Manuscript database
Anecdotal data have suggested that the effect of the western corn rootworm, Diabrotica virgifera virgifera LeConte, is greater under drought and the effect of drought is greater under rootworm infestations, but few experiments have controlled both moisture and rootworm levels. Field studies were con...
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Potassium fertilization mitigates the adverse effects of drought on selected Zea mays cultivars
USDA-ARS?s Scientific Manuscript database
In the present study, the role of potassium (K) in mitigating the adverse effects of drought stress (DS) on 2 maize (Zea mays L.) cultivars, ‘Shaandan 9’ (S9; drought-tolerant) and ‘Shaandan 911’ (S911; drought-sensitive), was assessed. K application increased dry matter (DM) across all growth stage...
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USDA-ARS?s Scientific Manuscript database
Climate models predict a reduction in precipitation and an increase in evapotranspiration rates in many regions of the world in coming decades, resulting in increased drought. In addition to decreasing plant growth and reproduction, drought also decreases the concentration (%) of nitrogen (N) and p...
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Nakabayashi, Ryo; Yonekura-Sakakibara, Keiko; Urano, Kaoru; Suzuki, Makoto; Yamada, Yutaka; Nishizawa, Tomoko; Matsuda, Fumio; Kojima, Mikiko; Sakakibara, Hitoshi; Shinozaki, Kazuo; Michael, Anthony J; Tohge, Takayuki; Yamazaki, Mami; Saito, Kazuki
2014-01-01
The notion that plants use specialized metabolism to protect against environmental stresses needs to be experimentally proven by addressing the question of whether stress tolerance by specialized metabolism is directly due to metabolites such as flavonoids. We report that flavonoids with radical scavenging activity mitigate against oxidative and drought stress in Arabidopsis thaliana. Metabolome and transcriptome profiling and experiments with oxidative and drought stress in wild-type, single overexpressors of MYB12/PFG1 (PRODUCTION OF FLAVONOL GLYCOSIDES1) or MYB75/PAP1 (PRODUCTION OF ANTHOCYANIN PIGMENT1), double overexpressors of MYB12 and PAP1, transparent testa4 (tt4) as a flavonoid-deficient mutant, and flavonoid-deficient MYB12 or PAP1 overexpressing lines (obtained by crossing tt4 and the individual MYB overexpressor) demonstrated that flavonoid overaccumulation was key to enhanced tolerance to such stresses. Antioxidative activity assays using 2,2-diphenyl-1-picrylhydrazyl, methyl viologen, and 3,3′-diaminobenzidine clearly showed that anthocyanin overaccumulation with strong in vitro antioxidative activity mitigated the accumulation of reactive oxygen species in vivo under oxidative and drought stress. These data confirm the usefulness of flavonoids for enhancing both biotic and abiotic stress tolerance in crops. PMID:24274116
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NASA Astrophysics Data System (ADS)
Bartlett, M. K.; Detto, M.; Pacala, S. W.
2017-12-01
The accurate prediction of tropical forest carbon fluxes is key to forecasting global climate, but forest responses to projected increases in CO2 and drought are highly uncertain. Here we present a dynamic optimization that derives the trajectory of stomatal conductance (gs) during drought, a key source of model uncertainty, from plant and soil water relations and the carbon economy of the plant hydraulic system. This optimization scheme is novel in two ways. First, by accounting for the ability of capacitance (i.e., the release of water from plant storage tissue; C) to buffer evaporative water loss and maintain gs during drought, this optimization captures both drought tolerant and avoidant hydraulic strategies. Second, by determining the optimal trajectory of plant and soil water potentials, this optimization quantifies species' impacts on the water available to competing plants. These advances allowed us to apply this optimization across the range of physiology trait values observed in tropical species to evaluate shifts in the competitively optimal trait values, or evolutionarily stable hydraulic strategy (ESS), under increased drought and CO2. Increasing the length of the dry season shifted the ESS towards more drought tolerant, rather than avoidant, trait values, and these shifts were larger for longer individual drought periods (i.e., more consecutive days without rainfall), even if the total time spent in drought was the same. Concurrently doubling the CO2 level reduced the magnitude of these shifts and slightly favored drought avoidant strategies under wet conditions. Overall, these analyses predicted that short, frequent droughts would allow elevated CO2 to shift the functional composition in tropical forests towards more drought avoidant species, while infrequent but long drought periods would shift the ESS to more drought tolerant trait values, despite increased CO2. Overall, these analyses quantified the impact of physiology traits on plant performance and competitive ability, and provide a mechanistic, trait-based approach to predict shifts in the functional composition of tropical forests under projected climatic conditions.
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Zhou, Rong; Yu, Xiaqing; Ottosen, Carl-Otto; Rosenqvist, Eva; Zhao, Liping; Wang, Yinlei; Yu, Wengui; Zhao, Tongmin; Wu, Zhen
2017-01-25
Abiotic stresses due to environmental factors could adversely affect the growth and development of crops. Among the abiotic stresses, drought and heat stress are two critical threats to crop growth and sustainable agriculture worldwide. Considering global climate change, incidence of combined drought and heat stress is likely to increase. The aim of this study was to shed light on plant growth performance and leaf physiology of three tomatoes cultivars ('Arvento', 'LA1994' and 'LA2093') under control, drought, heat and combined stress. Shoot fresh and dry weight, leaf area and relative water content of all cultivars significantly decreased under drought and combined stress as compared to control. The net photosynthesis and starch content were significantly lower under drought and combined stress than control in the three cultivars. Stomata and pore length of the three cultivars significantly decreased under drought and combined stress as compared to control. The tomato 'Arvento' was more affected by heat stress than 'LA1994' and 'LA2093' due to significant decreases in shoot dry weight, chlorophyll a and carotenoid content, starch content and NPQ (non-photochemical quenching) only in 'Arvento' under heat treatment. By comparison, the two heat-tolerant tomatoes were more affected by drought stress compared to 'Arvento' as shown by small stomatal and pore area, decreased sucrose content, Φ PSII (quantum yield of photosystem II), ETR (electron transport rate) and q L (fraction of open PSII centers) in 'LA1994' and 'LA2093'. The three cultivars showed similar response when subjected to the combination of drought and heat stress as shown by most physiological parameters, even though only 'LA1994' and 'LA2093' showed decreased F v /F m (maximum potential quantum efficiency of photosystem II), Φ PSII , ETR and q L under combined stress. The cultivars differing in heat sensitivity did not show difference in the combined stress sensitivity, indicating that selection for tomatoes with combined stress tolerance might not be correlated with the single stress tolerance. In this study, drought stress had a predominant effect on tomato over heat stress, which explained why simultaneous application of heat and drought revealed similar physiological responses to the drought stress. These results will uncover the difference and linkage between the physiological response of tomatoes to drought, heat and combined stress and be important for the selection and breeding of tolerant tomato cultivars under single and combine stress.
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Drought sensitivities of dominant plant functional types in the Colorado Plateau
NASA Astrophysics Data System (ADS)
Hoover, D. L.; Duniway, M.; Belnap, J.
2014-12-01
Drylands of the Southwestern US are predicted to experience greater water limitations with climate change due to changes in precipitation and increased warming. Certain plants may be living at or near their tolerance thresholds in these ecosystems and thus subtle changes in water availability may have dramatic effects on their performances. We imposed a four-year experiment in the Colorado Plateau to assess the vulnerability of this dryland ecosystem to chronic, but subtle drought using 40 sites varying in plant communities, parent materials and soil textures. Within a site, two plots were selected with matching cover of target species, which were randomly assigned to either control (ambient precipitation) or drought (35% reduction) treatments. Drought treatments were imposed year-round from 2011 through 2014. Over the course of the experiment, we examined plant cover changes and mortality of four dominant plant functional types (PFT's): C3 grasses, C4 grasses, C3 shrubs and C4 shrubs. We hypothesized that overall, grasses would be more sensitive to drought than shrubs, and that within these two groups, plants with C3 photosynthesis would be more sensitive than plants with C4 photosynthesis. During three of the four years, precipitation inputs were either near average (50th percentile, control) or dry (25th percentile, drought). However in 2012, both treatments experienced extremely dry growing season precipitation with the control and drought below the 5th and 1st percentiles, respectively. We observed three general responses to drought in this experiment: 1. change in cover with mortality (C3 grasses), 2. change in cover without mortality (C4 grasses and C4 shrubs) and 3. no change in cover or mortality (C3 shrubs). The dramatic responses of the C3 grasses suggest that this PFT is very sensitive to drought and it is living at or near its tolerance threshold in this region. While the C4 grasses also experienced cover changes, they did not experience widespread mortality and thus have higher tolerance to drought than the C3 grasses. Finally, contrary to our hypothesis, C3 shrubs were more drought tolerant than C4 shrubs. These results suggest that subtle changes in water availability may differentially impact key plant functional types and potentially alter the structure and function of this ecosystem.
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Tree-growth analyses to estimate tree species' drought tolerance.
Eilmann, Britta; Rigling, Andreas
2012-02-01
Climate change is challenging forestry management and practices. Among other things, tree species with the ability to cope with more extreme climate conditions have to be identified. However, while environmental factors may severely limit tree growth or even cause tree death, assessing a tree species' potential for surviving future aggravated environmental conditions is rather demanding. The aim of this study was to find a tree-ring-based method suitable for identifying very drought-tolerant species, particularly potential substitute species for Scots pine (Pinus sylvestris L.) in Valais. In this inner-Alpine valley, Scots pine used to be the dominating species for dry forests, but today it suffers from high drought-induced mortality. We investigate the growth response of two native tree species, Scots pine and European larch (Larix decidua Mill.), and two non-native species, black pine (Pinus nigra Arnold) and Douglas fir (Pseudotsuga menziesii Mirb. var. menziesii), to drought. This involved analysing how the radial increment of these species responded to increasing water shortage (abandonment of irrigation) and to increasingly frequent drought years. Black pine and Douglas fir are able to cope with drought better than Scots pine and larch, as they show relatively high radial growth even after irrigation has been stopped and a plastic growth response to drought years. European larch does not seem to be able to cope with these dry conditions as it lacks the ability to recover from drought years. The analysis of trees' short-term response to extreme climate events seems to be the most promising and suitable method for detecting how tolerant a tree species is towards drought. However, combining all the methods used in this study provides a complete picture of how water shortage could limit species.
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de Paiva Rolla, Amanda Alves; de Fátima Corrêa Carvalho, Josirley; Fuganti-Pagliarini, Renata; Engels, Cibelle; do Rio, Alexandre; Marin, Silvana Regina Rockenbach; de Oliveira, Maria Cristina Neves; Beneventi, Magda A; Marcelino-Guimarães, Francismar Corrêa; Farias, José Renato Bouças; Neumaier, Norman; Nakashima, Kazuo; Yamaguchi-Shinozaki, Kazuko; Nepomuceno, Alexandre Lima
2014-02-01
The development of drought tolerant plants is a high priority because the area suffering from drought is expected to increase in the future due to global warming. One strategy for the development of drought tolerance is to genetically engineer plants with transcription factors (TFs) that regulate the expression of several genes related to abiotic stress defense responses. This work assessed the performance of soybean plants overexpressing the TF DREB1A under drought conditions in the field and in the greenhouse. Drought was simulated in the greenhouse by progressively drying the soil of pot cultures of the P58 and P1142 lines. In the field, the performance of the P58 line and of 09D-0077, a cross between the cultivars BR16 and P58, was evaluated under four different water regimes: irrigation, natural drought (no irrigation) and water stress created using rain-out shelters in the vegetative or reproductive stages. Although the dehydration-responsive element-binding protein (DREB) plants did not outperform the cultivar BR16 in terms of yield, some yield components were increased when drought was introduced during the vegetative stage, such as the number of seeds, the number of pods with seeds and the total number of pods. The greenhouse data suggest that the higher survival rates of DREB plants are because of lower water use due to lower transpiration rates under well watered conditions. Further studies are needed to better characterize the soil and atmospheric conditions under which these plants may outperform the non-transformed parental plants.
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Wu, Songwei; Hu, Chengxiao; Tan, Qiling; Nie, Zhaojun; Sun, Xuecheng
2014-10-01
Molybdenum (Mo), as an essential trace element in plants, plays an essential role in abiotic stress tolerance of plants. To obtain a better understanding of drought tolerance enhanced by Mo, a hydroponic trial was conducted to investigate the effects of Mo on water utilization, antioxidant enzymes, non-enzymatic antioxidants, and osmotic-adjustment products in the Mo-efficient '97003' and Mo-inefficient '97014' under PEG simulated drought stress. Our results indicate that Mo application significantly enhanced Pn, chlorophyll, dry matter, grain yield, biomass, RWC and WUE and decreased Tr, Gs and water loss of wheat under drought stress, suggesting that Mo application improved the water utilization capacity in wheat. The activities of antioxidant enzymes such as superoxide dismutase, peroxidase, catalase, ascorbate peroxidase and the contents of non-enzymatic antioxidants content such as ascorbic acid, reduced glutathione, carotenoid were significantly increased and malonaldehyde contents were decreased by Mo application under PEG simulated drought stress, suggesting that Mo application enhanced the ability of scavenging active oxygen species. The osmotic-adjustment products such as soluble protein, proline and soluble sugar were also increased by Mo application under PEG simulated drought stress, indicating that Mo improved the osmotic adjustment ability in wheat. It is hypothesized that Mo application might improve the drought tolerance of wheat by enhancing water utilization capability and the abilities of antioxidative defense and osmotic adjustment. Similarities and differences between the Mo-efficient and Mo-inefficient cultivars wheat in response to Mo under drought stress are discussed. Copyright © 2014 Elsevier Masson SAS. All rights reserved.
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Nahar, Kamrun; Hasanuzzaman, Mirza; Alam, Md. Mahabub; Fujita, Masayuki
2015-01-01
Drought is considered one of the most acute environmental stresses presently affecting agriculture. We studied the role of exogenous glutathione (GSH) in conferring drought stress tolerance in mung bean (Vigna radiata L. cv. Binamoog-1) seedlings by examining the antioxidant defence and methylglyoxal (MG) detoxification systems and physiological features. Six-day-old seedlings were exposed to drought stress (−0.7 MPa), induced by polyethylene glycol alone and in combination with GSH (1 mM) for 24 and 48 h. Drought stress decreased seedling dry weight and leaf area; resulted in oxidative stress as evidenced by histochemical detection of hydrogen peroxide (H2O2) and O2⋅− in the leaves; increased lipid peroxidation (malondialdehyde), reactive oxygen species like H2O2 content and O2⋅− generation rate and lipoxygenase activity; and increased the MG level. Drought decreased leaf succulence, leaf chlorophyll and relative water content (RWC); increased proline (Pro); decreased ascorbate (AsA); increased endogenous GSH and glutathione disulfide (GSSG) content; decreased the GSH/GSSG ratio; increased ascorbate peroxidase and glutathione S-transferase activities; and decreased the activities of monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and catalase. The activities of glyoxalase I (Gly I) and glyoxalase II (Gly II) increased due to drought stress. In contrast to drought stress alone, exogenous GSH enhanced most of the components of the antioxidant and glyoxalase systems in drought-affected mung bean seedlings at 24 h, but GSH did not significantly affect AsA, Pro, RWC, leaf succulence and the activities of Gly I and DHAR after 48 h of stress. Thus, exogenous GSH supplementation with drought significantly enhanced the antioxidant components and successively reduced oxidative damage, and GSH up-regulated the glyoxalase system and reduced MG toxicity, which played a significant role in improving the physiological features and drought tolerance. PMID:26134121
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Liu, Xiaolong; Li, Xia; Dai, Chuanchao; Zhou, Jiayu; Yan, Ting; Zhang, Jinfei
2017-11-01
To understand the link between long-term drought tolerance and short-term drought responses in plants, transgenic rice (Oryza sativa L.) plants over-expressing the maize C 4- pepc gene encoding phosphoenolpyruvate carboxylase (PC) and wild-type (WT) rice plants were subjected to PEG 6000 treatments to simulate drought stress. Compared with WT, PC had the higher survival rate and net photosynthetic rate after 16days of drought treatment, and had higher relative water content in leaves after 2h of drought treatment as well, conferring drought tolerance. WT accumulated higher amounts of malondialdehyde, superoxide radicals, and H 2 O 2 than PC under the 2-h PEG 6000 treatment, indicating greater damages in WT. Results from pretreatments with a Ca 2+ chelator and/or antagonist showed that the regulation of the early drought response in PC was Ca 2+ -dependent. The NO and H 2 O 2 levels in PC lines were also up-regulated via Ca 2+ signals, indicating that Ca 2+ in PC lines also reacted upstream of NO and H 2 O 2 . 2-h drought treatment increased the transcripts of CPK9 and CPK4 in PC via positive up-regulation of Ca 2+ . The transcripts of NAC6 [NACs (NAM, ATAF1, ATAF2, and CUC2)] and bZIP60 (basic leucine zipper, bZIP) were up-regulated, but those of DREB2B (dehydration-responsive element-binding protein, DREB) were down-regulated, both via Ca 2+ signals in PC. PEPC activity, expressions of C 4 -pepc, and the antioxidant enzyme activities in PC lines were up-regulated via Ca 2+ . These results indicated that Ca 2+ signals in PC lines can up-regulate the NAC6 and bZIP60 and the downstream targets for early drought responses, conferring drought tolerance for the long term. Copyright © 2017 Elsevier GmbH. All rights reserved.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Cairney, J.; Hays, D.; Stockand, J.D.
1991-05-01
The rangeland shrub Atriplex canescens (saltbush) is extremely drought-tolerant and is capable of growing at water potentials below {minus}40 bar. To discover the molecular basis of this tolerance, the authors have isolated a number of cDNA clones of drought-stress induced genes. Analysis of the nucleotide sequence and expression of these genes in different tissues and in response to different stresses reveals the diversity of the stress response. Members of a drought-induced, multi-gene family, have been sequenced. Although 95% homologous, non-conservative substitutions result in proteins of different tertiary structure. Additionally, the genes are expressed through a number of mature forms ofmore » mRNA which may arise by alternative RNA processing.« less
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Conceptual framework for drought phenotyping during molecular breeding.
Salekdeh, Ghasem Hosseini; Reynolds, Matthew; Bennett, John; Boyer, John
2009-09-01
Drought is a major threat to agricultural production and drought tolerance is a prime target for molecular approaches to crop improvement. To achieve meaningful results, these approaches must be linked with suitable phenotyping protocols at all stages, such as the screening of germplasm collections, mutant libraries, mapping populations, transgenic lines and breeding materials and the design of OMICS and quantitative trait loci (QTLs) experiments. Here we present a conceptual framework for molecular breeding for drought tolerance based on the Passioura equation of expressing yield as the product of water use (WU), water use efficiency (WUE) and harvest index (HI). We identify phenotyping protocols that address each of these factors, describe their key features and illustrate their integration with different molecular approaches.
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dos Santos, Ivanildes C.; de Almeida, Alex-Alan Furtado; Anhert, Dário; da Conceição, Alessandro S.; Pirovani, Carlos P.; Pires, José L.; Valle, Raúl René; Baligar, Virupax C.
2014-01-01
Six months-old seminal plants of 36 cacao genotypes grown under greenhouse conditions were subjected to two soil water regimes (control and drought) to assess, the effects of water deficit on growth, chemical composition and oxidative stress. In the control, soil moisture was maintained near field capacity with leaf water potentials (ΨWL) ranging from −0.1 to −0.5 MPa. In the drought treatment, the soil moisture was reduced gradually by withholding additional water until ΨWL reached values of between −2.0 to −2.5 MPa. The tolerant genotypes PS-1319, MO-20 and MA-15 recorded significant increases in guaiacol peroxidase activity reflecting a more efficient antioxidant metabolism. In relation to drought tolerance, the most important variables in the distinguishing contrasting groups were: total leaf area per plant; leaf, stem and total dry biomass; relative growth rate; plant shoot biomass and leaf content of N, Ca, and Mg. From the results of these analyses, six genotypes were selected with contrasting characteristics for tolerance to soil water deficit [CC-40, C. SUL-4 and SIC-2 (non-tolerant) and MA-15, MO-20, and PA-13 (tolerant)] for further assessment of the expression of genes NCED5, PP2C, psbA and psbO to water deficit. Increased expression of NCED5, PP2C, psbA and psbO genes were found for non-tolerant genotypes, while in the majority of tolerant genotypes there was repression of these genes, with the exception of PA-13 that showed an increased expression of psbA. Mutivariate analysis showed that growth variables, leaf and total dry biomass, relative growth rate as well as Mg content of the leaves were the most important factor in the classification of the genotypes as tolerant, moderately tolerant and sensitive to water deficit. Therefore these variables are reliable plant traits in the selection of plants tolerant to drought. PMID:25541723
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Santos, Ivanildes C Dos; Almeida, Alex-Alan Furtado de; Anhert, Dário; Conceição, Alessandro S da; Pirovani, Carlos P; Pires, José L; Valle, Raúl René; Baligar, Virupax C
2014-01-01
Six months-old seminal plants of 36 cacao genotypes grown under greenhouse conditions were subjected to two soil water regimes (control and drought) to assess, the effects of water deficit on growth, chemical composition and oxidative stress. In the control, soil moisture was maintained near field capacity with leaf water potentials (ΨWL) ranging from -0.1 to -0.5 MPa. In the drought treatment, the soil moisture was reduced gradually by withholding additional water until ΨWL reached values of between -2.0 to -2.5 MPa. The tolerant genotypes PS-1319, MO-20 and MA-15 recorded significant increases in guaiacol peroxidase activity reflecting a more efficient antioxidant metabolism. In relation to drought tolerance, the most important variables in the distinguishing contrasting groups were: total leaf area per plant; leaf, stem and total dry biomass; relative growth rate; plant shoot biomass and leaf content of N, Ca, and Mg. From the results of these analyses, six genotypes were selected with contrasting characteristics for tolerance to soil water deficit [CC-40, C. SUL-4 and SIC-2 (non-tolerant) and MA-15, MO-20, and PA-13 (tolerant)] for further assessment of the expression of genes NCED5, PP2C, psbA and psbO to water deficit. Increased expression of NCED5, PP2C, psbA and psbO genes were found for non-tolerant genotypes, while in the majority of tolerant genotypes there was repression of these genes, with the exception of PA-13 that showed an increased expression of psbA. Mutivariate analysis showed that growth variables, leaf and total dry biomass, relative growth rate as well as Mg content of the leaves were the most important factor in the classification of the genotypes as tolerant, moderately tolerant and sensitive to water deficit. Therefore these variables are reliable plant traits in the selection of plants tolerant to drought.
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Michael J. Clifford; Patrick D. Royer; Neil S. Cobb; David D. Breshears; Paulette L. Ford
2013-01-01
Recent regional tree die-off events appear to have been triggered by a combination of drought and heat - referred to as 'global-change-type drought'. To complement experiments focused on resolving mechanisms of drought-induced tree mortality, an evaluation of how patterns of tree die-off relate to highly spatially variable precipitation is needed....
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Zhang, Jiachang; Xiao, Yitao; Yue, Yuesen; Duan, Liusheng; Zhang, Mingcai; Li, Zhaohu
2013-01-01
Abscisic acid (ABA) is a key component of the signaling system that integrates plant adaptive responses to abiotic stress. Overexpression of Arabidopsis molybdenum cofactor sulfurase gene (LOS5) in maize markedly enhanced the expression of ZmAO and aldehyde oxidase (AO) activity, leading to ABA accumulation and increased drought tolerance. Transgenic maize (Zea mays L.) exhibited the expected reductions in stomatal aperture, which led to decreased water loss and maintenance of higher relative water content (RWC) and leaf water potential. Also, transgenic maize subjected to drought treatment exhibited lower leaf wilting, electrolyte leakage, malondialdehyde (MDA) and H2O2 content, and higher activities of antioxidative enzymes and proline content compared to wild-type (WT) maize. Moreover, overexpression of LOS5 enhanced the expression of stress-regulated genes such as Rad 17, NCED1, CAT1, and ZmP5CS1 under drought stress conditions, and increased root system development and biomass yield after re-watering. The increased drought tolerance in transgenic plants was associated with ABA accumulation via activated AO and expression of stress-related gene via ABA induction, which sequentially induced a set of favorable stress-related physiological and biochemical responses. PMID:23326325
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Lu, Yao; Li, Yajun; Zhang, Jiachang; Xiao, Yitao; Yue, Yuesen; Duan, Liusheng; Zhang, Mingcai; Li, Zhaohu
2013-01-01
Abscisic acid (ABA) is a key component of the signaling system that integrates plant adaptive responses to abiotic stress. Overexpression of Arabidopsis molybdenum cofactor sulfurase gene (LOS5) in maize markedly enhanced the expression of ZmAO and aldehyde oxidase (AO) activity, leading to ABA accumulation and increased drought tolerance. Transgenic maize (Zea mays L.) exhibited the expected reductions in stomatal aperture, which led to decreased water loss and maintenance of higher relative water content (RWC) and leaf water potential. Also, transgenic maize subjected to drought treatment exhibited lower leaf wilting, electrolyte leakage, malondialdehyde (MDA) and H(2)O(2) content, and higher activities of antioxidative enzymes and proline content compared to wild-type (WT) maize. Moreover, overexpression of LOS5 enhanced the expression of stress-regulated genes such as Rad 17, NCED1, CAT1, and ZmP5CS1 under drought stress conditions, and increased root system development and biomass yield after re-watering. The increased drought tolerance in transgenic plants was associated with ABA accumulation via activated AO and expression of stress-related gene via ABA induction, which sequentially induced a set of favorable stress-related physiological and biochemical responses.
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Jiang, Yiwei
2013-01-01
Drought is a major environmental stress limiting growth of perennial grasses in temperate regions. Plant drought tolerance is a complex trait that is controlled by multiple genes. Candidate gene association mapping provides a powerful tool for dissection of complex traits. Candidate gene association mapping of drought tolerance traits was conducted in 192 diverse perennial ryegrass (Lolium perenne L.) accessions from 43 countries. The panel showed significant variations in leaf wilting, leaf water content, canopy and air temperature difference, and chlorophyll fluorescence under well-watered and drought conditions across six environments. Analysis of 109 simple sequence repeat markers revealed five population structures in the mapping panel. A total of 2520 expression-based sequence readings were obtained for a set of candidate genes involved in antioxidant metabolism, dehydration, water movement across membranes, and signal transduction, from which 346 single nucleotide polymorphisms were identified. Significant associations were identified between a putative LpLEA3 encoding late embryogenesis abundant group 3 protein and a putative LpFeSOD encoding iron superoxide dismutase and leaf water content, as well as between a putative LpCyt Cu-ZnSOD encoding cytosolic copper-zinc superoxide dismutase and chlorophyll fluorescence under drought conditions. Four of these identified significantly associated single nucleotide polymorphisms from these three genes were also translated to amino acid substitutions in different genotypes. These results indicate that allelic variation in these genes may affect whole-plant response to drought stress in perennial ryegrass. PMID:23386684
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Environmental gradients and grassland trait variation: Insight into the effects of climate change
NASA Astrophysics Data System (ADS)
Tardella, Federico M.; Piermarteri, Karina; Malatesta, Luca; Catorci, Andrea
2016-10-01
The research aim was to understand how variation of temperature and water availability drives trait assemblage of seminatural grasslands in sub-Mediterranean climate, where climate change is expected to intensify summer aridity. In the central Italy, we recorded species abundance and elevation, slope aspect and angle in 129 plots. The traits we analysed were life span, growth form, clonality, belowground organs, leaf traits, plant height, seed mass, and palatability. We used Ellenberg's indicators as a proxy to assess air temperature and soil moisture gradients. From productive to harsh conditions, we observed a shift from tolerance to avoidance strategies, and a change in resource allocation strategies to face competition and stress or that maximize exploitation of patchily distributed soil resource niches. In addition, we found that the increase of temperature and water scarcity leads to the establishment of regeneration strategies that enable plants to cope with the unpredictability of changes in stress intensity and duration. Since the dry habitats of higher elevations are also constrained by winter cold stress, we argue that, within the sub-Mediterranean bioclimate, climate change will likely lead to a variation in dominance inside plant communities rather than a shift upwards of species ranges. At higher elevations, drought-adaptive traits might become more abundant on south-facing slopes that are less stressed by winter low temperatures; traits related to productive conditions and cold stress would be replaced on north-facing slopes by those adapted to overcome both the drought and the cold stresses.
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Nataraja, Karaba N.; Udayakumar, M.
2015-01-01
Basic helix-loop-helix (bHLH) transcription factors constitute one of the largest families in plants and are known to be involved in various developmental processes and stress tolerance. We report the characterization of a stress responsive bHLH transcription factor from stress adapted species finger millet which is homologous to OsbHLH57 and designated as EcbHLH57. The full length sequence of EcbHLH57 consisted of 256 amino acids with a conserved bHLH domain followed by leucine repeats. In finger millet, EcbHLH57 transcripts were induced by ABA, NaCl, PEG, methyl viologen (MV) treatments and drought stress. Overexpression of EcbHLH57 in tobacco significantly increased the tolerance to salinity and drought stress with improved root growth. Transgenic plants showed higher photosynthetic rate and stomatal conductance under drought stress that resulted in higher biomass. Under long-term salinity stress, the transgenic plants accumulated higher seed weight/pod and pod number. The transgenic plants were also tolerant to oxidative stress and showed less accumulation of H202 and MDA levels. The overexpression of EcbHLH57 enhanced the expression of stress responsive genes such as LEA14, rd29A, rd29B, SOD, APX, ADH1, HSP70 and also PP2C and hence improved tolerance to diverse stresses. PMID:26366726
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Vance, Nan C.; Copes, Donald O.; Zaerr, Joe B.
1990-01-01
Proteins were radiolabeled and extracted from needles of Pinus ponderosa var scopulorum (Dougl. ex Laws.) seedlings progressively drought-stressed for about 1 month. A set of novel, low molecular weight proteins was detected in fluorographs of two-dimensional gels when relative water content of needles fell below 70%. Their synthesis was undetectable in the fully recovered seedlings within 48 hours after rewatering. In similarly stressed seedlings that were shaded to 10% full light, the low molecular weight polypeptides were not detected or appeared at very low levels. The shaded seedlings, in which drought tolerance was reduced, did not recover upon termination of the drought. The results suggest that protein synthesis induced by water deficit in drought-tolerant seedlings may contribute to resisting the effects of cellular dehydration. Images Figure 1 Figure 2 PMID:16667397
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Dias, Kaio Olímpio Das Graças; Gezan, Salvador Alejandro; Guimarães, Claudia Teixeira; Nazarian, Alireza; da Costa E Silva, Luciano; Parentoni, Sidney Netto; de Oliveira Guimarães, Paulo Evaristo; de Oliveira Anoni, Carina; Pádua, José Maria Villela; de Oliveira Pinto, Marcos; Noda, Roberto Willians; Ribeiro, Carlos Alexandre Gomes; de Magalhães, Jurandir Vieira; Garcia, Antonio Augusto Franco; de Souza, João Cândido; Guimarães, Lauro José Moreira; Pastina, Maria Marta
2018-07-01
Breeding for drought tolerance is a challenging task that requires costly, extensive, and precise phenotyping. Genomic selection (GS) can be used to maximize selection efficiency and the genetic gains in maize (Zea mays L.) breeding programs for drought tolerance. Here, we evaluated the accuracy of genomic selection (GS) using additive (A) and additive + dominance (AD) models to predict the performance of untested maize single-cross hybrids for drought tolerance in multi-environment trials. Phenotypic data of five drought tolerance traits were measured in 308 hybrids along eight trials under water-stressed (WS) and well-watered (WW) conditions over two years and two locations in Brazil. Hybrids' genotypes were inferred based on their parents' genotypes (inbred lines) using single-nucleotide polymorphism markers obtained via genotyping-by-sequencing. GS analyses were performed using genomic best linear unbiased prediction by fitting a factor analytic (FA) multiplicative mixed model. Two cross-validation (CV) schemes were tested: CV1 and CV2. The FA framework allowed for investigating the stability of additive and dominance effects across environments, as well as the additive-by-environment and the dominance-by-environment interactions, with interesting applications for parental and hybrid selection. Results showed differences in the predictive accuracy between A and AD models, using both CV1 and CV2, for the five traits in both water conditions. For grain yield (GY) under WS and using CV1, the AD model doubled the predictive accuracy in comparison to the A model. Through CV2, GS models benefit from borrowing information of correlated trials, resulting in an increase of 40% and 9% in the predictive accuracy of GY under WS for A and AD models, respectively. These results highlight the importance of multi-environment trial analyses using GS models that incorporate additive and dominance effects for genomic predictions of GY under drought in maize single-cross hybrids.
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Tolerance to multiple climate stressors: a case study of Douglas-fir drought and cold hardiness
Sheel Bansal; Connie Harrington; Brad St. Clair
2016-01-01
1. Drought and freeze events are two of the most common forms of climate extremes which result in tree damage or death, and the frequency and intensity of both stressors may increase with climate change. Few studies have examined natural covariation in stress tolerance traits to cope with multiple stressors among wild plant populations. 2. We assessed the...
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Competition amplifies drought stress in forests across broad climatic and compositional gradients
Kelly E. Gleason; John B. Bradford; Alessandra Bottero; Anthony W. D' Amato; Shawn Fraver; Brian J. Palik; Michael A. Battaglia; Louis Iverson; Laura Kenefic; Christel C. Kern
2017-01-01
Forests around the world are experiencing increasingly severe droughts and elevated competitive intensity due to increased tree density. However, the influence of interactions between drought and competition on forest growth remains poorly understood. Using a unique dataset of stand-scale dendrochronology sampled from 6405 trees, we quantified how annual growth of...
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Borah, Pratikshya; Sharma, Eshan; Kaur, Amarjot; Chandel, Girish; Mohapatra, Trilochan; Kapoor, Sanjay; Khurana, Jitendra P.
2017-01-01
Traditional cultivars of rice in India exhibit tolerance to drought stress due to their inherent genetic variations. Here we present comparative physiological and transcriptome analyses of two contrasting cultivars, drought tolerant Dhagaddeshi (DD) and susceptible IR20. Microarray analysis revealed several differentially expressed genes (DEGs) exclusively in DD as compared to IR20 seedlings exposed to 3 h drought stress. Physiologically, DD seedlings showed higher cell membrane stability and differential ABA accumulation in response to dehydration, coupled with rapid changes in gene expression. Detailed analyses of metabolic pathways enriched in expression data suggest interplay of ABA dependent along with secondary and redox metabolic networks that activate osmotic and detoxification signalling in DD. By co-localization of DEGs with QTLs from databases or published literature for physiological traits of DD and IR20, candidate genes were identified including those underlying major QTL qDTY1.1 in DD. Further, we identified previously uncharacterized genes from both DD and IR20 under drought conditions including OsWRKY51, OsVP1 and confirmed their expression by qPCR in multiple rice cultivars. OsFBK1 was also functionally validated in susceptible PB1 rice cultivar and Arabidopsis for providing drought tolerance. Some of the DEGs mapped to the known QTLs could thus, be of potential significance for marker-assisted breeding. PMID:28181537
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Saiki, Shin-Taro; Ishida, Atsushi; Yoshimura, Kenichi; Yazaki, Kenichi
2017-06-07
Drought-induced tree die-off related to climate change is occurring worldwide and affects the carbon stocks and biodiversity in forest ecosystems. Hydraulic failure and carbon starvation are two commonly proposed mechanisms for drought-induced tree die-off. Here, we show that inhibited branchlet respiration and soil-to-leaf hydraulic conductance, likely caused by cell damage, occur prior to hydraulic failure (xylem embolism) and carbon starvation (exhaustion of stored carbon in sapwood) in a drought-tolerant woody species, Rhaphiolepis wrightiana Maxim. The ratio of the total leaf area to the twig sap area was used as a health indicator after drought damage. Six adult trees with different levels of tree health and one dead adult tree were selected. Two individuals having the worst and second worst health among the six live trees died three months after our study was conducted. Soil-to-leaf hydraulic conductance and leaf gas exchange rates decreased linearly as tree health declined, whereas xylem cavitation and total non-structural carbon remained unchanged in the branchlets except in the dead and most unhealthy trees. Respiration rates and the number of living cells in the sapwood decreased linearly as tree health declined. This study is the first report on the importance of dehydration tolerance and respiration maintenance in living cells.
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Anjum, Shakeel A.; Ashraf, Umair; Tanveer, Mohsin; Khan, Imran; Hussain, Saddam; Shahzad, Babar; Zohaib, Ali; Abbas, Farhat; Saleem, Muhammad F.; Ali, Iftikhar; Wang, Long C.
2017-01-01
Consequences of drought stress in crop production systems are perhaps more deleterious than other abiotic stresses under changing climatic scenarios. Regulations of physio-biochemical responses of plants under drought stress can be used as markers for drought stress tolerance in selection and breeding. The present study was conducted to appraise the performance of three different maize hybrids (Dong Dan 80, Wan Dan 13, and Run Nong 35) under well-watered, low, moderate and SD conditions maintained at 100, 80, 60, and 40% of field capacity, respectively. Compared with well-watered conditions, drought stress caused oxidative stress by excessive production of reactive oxygen species (ROS) which led to reduced growth and yield formation in all maize hybrids; nevertheless, negative effects of drought stress were more prominent in Run Nong 35. Drought-induced osmolyte accumulation and strong enzymatic and non-enzymatic defense systems prevented the severe damage in Dong Dan 80. Overall performance of all maize hybrids under drought stress was recorded as: Dong Dan 80 > Wan Dan 13 > Run Nong 35 with 6.39, 7.35, and 16.55% yield reductions. Consequently, these biochemical traits and differential physiological responses might be helpful to develop drought tolerance genotypes that can withstand water-deficit conditions with minimum yield losses. PMID:28220130
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Effect of water stress on in vitro mycelium cultures of two mycorrhizal desert truffles.
Navarro-Ródenas, Alfonso; Lozano-Carrillo, M Cecilia; Pérez-Gilabert, Manuela; Morte, Asunción
2011-05-01
The ability of two species of desert truffle, Terfezia claveryi strain TcS2 and Picoa lefebvrei strain OL2, to tolerate water stress in pure culture has been investigated. Both T. claveryi and P. lefebvrei strains exhibited a mycelium growth pattern characteristic of drought tolerant species. However, they were only tolerant to moderate water stress, below -1.07 MPa, with the P. lefebvrei isolate being slightly more drought tolerant than the T. claveryi isolate. The increased alkaline phosphatase (ALP) activity observed in both fungi at moderate water stress with respect to the control indicated the functional adaptation of these mycelia to these drought conditions. ALP activity can be used as an indicator of the metabolic activity of these fungi. Slight water stress (-0.45 MPa) could improve mycelial inoculum production of these desert truffles. Moreover, P. lefebvrei could be a good candidate for further desert truffle mycorrhizal plant cultivation programmes in semiarid Mediterranean areas.
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Tripathi, Prateek; Rabara, Roel C; Reese, R Neil; Miller, Marissa A; Rohila, Jai S; Subramanian, Senthil; Shen, Qingxi J; Morandi, Dominique; Bücking, Heike; Shulaev, Vladimir; Rushton, Paul J
2016-02-09
The purpose of this project was to identify metabolites, proteins, genes, and promoters associated with water stress responses in soybean. A number of these may serve as new targets for the biotechnological improvement of drought responses in soybean (Glycine max). We identified metabolites, proteins, and genes that are strongly up or down regulated during rapid water stress following removal from a hydroponics system. 163 metabolites showed significant changes during water stress in roots and 93 in leaves. The largest change was a root-specific 160-fold increase in the coumestan coumestrol making it a potential biomarker for drought and a promising target for improving drought responses. Previous reports suggest that coumestrol stimulates mycorrhizal colonization and under certain conditions mycorrhizal plants have improved drought tolerance. This suggests that coumestrol may be part of a call for help to the rhizobiome during stress. About 3,000 genes were strongly up-regulated by drought and we identified regulators such as ERF, MYB, NAC, bHLH, and WRKY transcription factors, receptor-like kinases, and calcium signaling components as potential targets for soybean improvement as well as the jasmonate and abscisic acid biosynthetic genes JMT, LOX1, and ABA1. Drought stressed soybean leaves show reduced mRNA levels of stomatal development genes including FAMA-like, MUTE-like and SPEECHLESS-like bHLH transcription factors and leaves formed after drought stress had a reduction in stomatal density of 22.34 % and stomatal index of 17.56 %. This suggests that reducing stomatal density may improve drought tolerance. MEME analyses suggest that ABRE (CACGT/CG), CRT/DRE (CCGAC) and a novel GTGCnTGC/G element play roles in transcriptional activation and these could form components of synthetic promoters to drive expression of transgenes. Using transformed hairy roots, we validated the increase in promoter activity of GmWRKY17 and GmWRKY67 during dehydration and after 20 μM ABA treatment. Our toolbox provides new targets and strategies for improving soybean drought tolerance and includes the coumestan coumestrol, transcription factors that regulate stomatal density, water stress-responsive WRKY gene promoters and a novel DNA element that appears to be enriched in water stress responsive promoters.
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Zang, Xinshan; Geng, Xiaoli; Liu, Kelu; Wang, Fei; Liu, Zhenshan; Zhang, Liyuan; Zhao, Yue; Tian, Xuejun; Hu, Zhaorong; Yao, Yingyin; Ni, Zhongfu; Xin, Mingming; Sun, Qixin; Peng, Huiru
2017-05-01
Abiotic stresses, such as heat and drought, are major environmental factors restricting crop productivity and quality worldwide. A plastid outer envelope protein gene, TaOEP16-2, was identified from our previous transcriptome analysis [1,2]. In this study, the isolation and functional characterization of the TaOEP16-2 gene was reported. Three homoeologous sequences of TaOEP16-2 were isolated from hexaploid wheat, which were localized on the chromosomes 5A, 5B and 5D, respectively. These three homoeologues exhibited different expression patterns under heat stress conditions, TaOEP16-2-5B was the dominant one, and TaOEP16-2-5B was selected for further analysis. Compared with wild type (WT) plants, transgenic Arabidopsis plants overexpressing the TaOEP16-2-5B gene exhibited enhanced tolerance to heat stress, which was supported by improved survival rate, strengthened cell membrane stability and increased sucrose content. It was also found that TaOEP16-2 was induced by drought stress and involved in drought stress tolerance. TaOEP16-2-5B has the same function in ABA-controlled seed germination as AtOEP16-2. Our results suggest that TaOEP16-2-5B plays an important role in heat and drought stress tolerance, and could be utilized in transgenic breeding of wheat and other crop plants. Copyright © 2017 Elsevier B.V. All rights reserved.
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Tamirisa, Srinath; Vudem, Dashavantha Reddy; Khareedu, Venkateswara Rao
2014-01-01
A potent cold and drought regulatory protein-encoding gene (CcCDR) was isolated from the subtractive cDNA library of pigeonpea plants subjected to drought stress. CcCDR was induced by different abiotic stress conditions in pigeonpea. Overexpression of CcCDR in Arabidopsis thaliana imparted enhanced tolerance against major abiotic stresses, namely drought, salinity, and low temperature, as evidenced by increased biomass, root length, and chlorophyll content. Transgenic plants also showed increased levels of antioxidant enzymes, proline, and reducing sugars under stress conditions. Furthermore, CcCDR-transgenic plants showed enhanced relative water content, osmotic potential, and cell membrane stability, as well as hypersensitivity to abscisic acid (ABA) as compared with control plants. Localization studies confirmed that CcCDR could enter the nucleus, as revealed by intense fluorescence, indicating its possible interaction with various nuclear proteins. Microarray analysis revealed that 1780 genes were up-regulated in CcCDR-transgenics compared with wild-type plants. Real-time PCR analysis on selected stress-responsive genes, involved in ABA-dependent and -independent signalling networks, revealed higher expression levels in transgenic plants, suggesting that CcCDR acts upstream of these genes. The overall results demonstrate the explicit role of CcCDR in conferring multiple abiotic stress tolerance at the whole-plant level. The multifunctional CcCDR seems promising as a prime candidate gene for enhancing abiotic stress tolerance in diverse plants. PMID:24868035
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Wang, Lin; Li, Qingtian; Lei, Qiong; Feng, Chao; Gao, Yinan; Zheng, Xiaodong; Zhao, Yu; Wang, Zhi; Kong, Jin
2015-01-01
Plants are unavoidably subjected to various abiotic stressors, including high salinity, drought and low temperature, which results in water deficit and even death. Water uptake and transportation play a critical role in response to these stresses. Many aquaporin proteins, localized at different tissues, function in various transmembrane water movements. We targeted at the key aquaporin in charge of both water uptake in roots and radial water transportation from vascular tissues through the whole plant. The MzPIP2;1 gene encoding a plasma membrane intrinsic protein was cloned from salt-tolerant apple rootstock Malus zumi Mats. The GUS gene was driven by MzPIP2;1 promoter in transgenic Arabidopsis. It indicated that MzPIP2;1 might function in the epidermal and vascular cells of roots, parenchyma cells around vessels through the stems and vascular tissues of leaves. The ectopically expressed MzPIP2;1 conferred the transgenic Arabidopsis plants enhanced tolerance to slight salt and drought stresses, but sensitive to moderate salt stress, which was indicated by root length, lateral root number, fresh weight and K+/Na+ ratio. In addition, the possible key cis-elements in response to salt, drought and cold stresses were isolated by the promoter deletion experiment. The MzPIP2;1 protein, as a PIP2 aquaporins subgroup member, involved in radial water movement, controls water absorption and usage efficiency and alters transgenic plants drought and salt tolerance.
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Shi, Jinrui; Habben, Jeffrey E.; Archibald, Rayeann L.; Drummond, Bruce J.; Chamberlin, Mark A.; Williams, Robert W.; Lafitte, H. Renee; Weers, Ben P.
2015-01-01
Lack of sufficient water is a major limiting factor to crop production worldwide, and the development of drought-tolerant germplasm is needed to improve crop productivity. The phytohormone ethylene modulates plant growth and development as well as plant response to abiotic stress. Recent research has shown that modifying ethylene biosynthesis and signaling can enhance plant drought tolerance. Here, we report novel negative regulators of ethylene signal transduction in Arabidopsis (Arabidopsis thaliana) and maize (Zea mays). These regulators are encoded by the ARGOS gene family. In Arabidopsis, overexpression of maize ARGOS1 (ZmARGOS1), ZmARGOS8, Arabidopsis ARGOS homolog ORGAN SIZE RELATED1 (AtOSR1), and AtOSR2 reduced plant sensitivity to ethylene, leading to enhanced drought tolerance. RNA profiling and genetic analysis suggested that the ZmARGOS1 transgene acts between an ethylene receptor and CONSTITUTIVE TRIPLE RESPONSE1 in the ethylene signaling pathway, affecting ethylene perception or the early stages of ethylene signaling. Overexpressed ZmARGOS1 is localized to the endoplasmic reticulum and Golgi membrane, where the ethylene receptors and the ethylene signaling protein ETHYLENE-INSENSITIVE2 and REVERSION-TO-ETHYLENE SENSITIVITY1 reside. In transgenic maize plants, overexpression of ARGOS genes also reduces ethylene sensitivity. Moreover, field testing showed that UBIQUITIN1:ZmARGOS8 maize events had a greater grain yield than nontransgenic controls under both drought stress and well-watered conditions. PMID:26220950
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Shi, Jinrui; Habben, Jeffrey E; Archibald, Rayeann L; Drummond, Bruce J; Chamberlin, Mark A; Williams, Robert W; Lafitte, H Renee; Weers, Ben P
2015-09-01
Lack of sufficient water is a major limiting factor to crop production worldwide, and the development of drought-tolerant germplasm is needed to improve crop productivity. The phytohormone ethylene modulates plant growth and development as well as plant response to abiotic stress. Recent research has shown that modifying ethylene biosynthesis and signaling can enhance plant drought tolerance. Here, we report novel negative regulators of ethylene signal transduction in Arabidopsis (Arabidopsis thaliana) and maize (Zea mays). These regulators are encoded by the ARGOS gene family. In Arabidopsis, overexpression of maize ARGOS1 (ZmARGOS1), ZmARGOS8, Arabidopsis ARGOS homolog ORGAN SIZE RELATED1 (AtOSR1), and AtOSR2 reduced plant sensitivity to ethylene, leading to enhanced drought tolerance. RNA profiling and genetic analysis suggested that the ZmARGOS1 transgene acts between an ethylene receptor and CONSTITUTIVE TRIPLE RESPONSE1 in the ethylene signaling pathway, affecting ethylene perception or the early stages of ethylene signaling. Overexpressed ZmARGOS1 is localized to the endoplasmic reticulum and Golgi membrane, where the ethylene receptors and the ethylene signaling protein ETHYLENE-INSENSITIVE2 and REVERSION-TO-ETHYLENE SENSITIVITY1 reside. In transgenic maize plants, overexpression of ARGOS genes also reduces ethylene sensitivity. Moreover, field testing showed that UBIQUITIN1:ZmARGOS8 maize events had a greater grain yield than nontransgenic controls under both drought stress and well-watered conditions. © 2015 American Society of Plant Biologists. All Rights Reserved.
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Characterization of Soybean Genetically Modified for Drought Tolerance in Field Conditions
Fuganti-Pagliarini, Renata; Ferreira, Leonardo C.; Rodrigues, Fabiana A.; Molinari, Hugo B. C.; Marin, Silvana R. R.; Molinari, Mayla D. C.; Marcolino-Gomes, Juliana; Mertz-Henning, Liliane M.; Farias, José R. B.; de Oliveira, Maria C. N.; Neumaier, Norman; Kanamori, Norihito; Fujita, Yasunari; Mizoi, Junya; Nakashima, Kazuo; Yamaguchi-Shinozaki, Kazuko; Nepomuceno, Alexandre L.
2017-01-01
Drought is one of the most stressful environmental factor causing yield and economic losses in many soybean-producing regions. In the last decades, transcription factors (TFs) are being used to develop genetically modified plants more tolerant to abiotic stresses. Dehydration responsive element binding (DREB) and ABA-responsive element-binding (AREB) TFs were introduced in soybean showing improved drought tolerance, under controlled conditions. However, these results may not be representative of the way in which plants behave over the entire season in the real field situation. Thus, the objectives of this study were to analyze agronomical traits and physiological parameters of AtDREB1A (1Ab58), AtDREB2CA (1Bb2193), and AtAREB1 (1Ea2939) GM lines under irrigated (IRR) and non-irrigated (NIRR) conditions in a field experiment, over two crop seasons and quantify transgene and drought-responsive genes expression. Results from season 2013/2014 revealed that line 1Ea2939 showed higher intrinsic water use and leaf area index. Lines 1Ab58 and 1Bb2193 showed a similar behavior to wild-type plants in relation to chlorophyll content. Oil and protein contents were not affected in transgenic lines in NIRR conditions. Lodging, due to plentiful rain, impaired yield from the 1Ea2939 line in IRR conditions. qPCR results confirmed the expression of the inserted TFs and drought-responsive endogenous genes. No differences were identified in the field experiment performed in crop season 2014/2015, probably due to the optimum rainfall volume during the cycle. These field screenings showed promising results for drought tolerance. However, additional studies are needed in further crop seasons and other sites to better characterize how these plants may outperform the WT under field water deficit. PMID:28443101
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Ortiz, N; Armada, E; Duque, E; Roldán, A; Azcón, R
2015-02-01
Autochthonous microorganisms [a consortium of arbuscular-mycorrhizal (AM) fungi and Bacillus thuringiensis (Bt)] were assayed and compared to Rhizophagus intraradices (Ri), Bacillus megaterium (Bm) or Pseudomonas putida (Psp) and non-inoculation on Trifolium repens in a natural arid soil under drought conditions. The autochthonous bacteria Bt and the allochthonous bacteria Psp increased nutrients and the relative water content and decreased stomatal conductance, electrolyte leakage, proline and APX activity, indicating their abilities to alleviate the drought stress. Mycorrhizal inoculation significantly enhanced plant growth, nutrient uptake and the relative water content, particularly when associated with specific bacteria minimizing drought stress-imposed effects. Specific combinations of autochthonous or allochthonous inoculants also contributed to plant drought tolerance by changing proline and antioxidative activities. However, non-inoculated plants had low relative water and nutrients contents, shoot proline accumulation and glutathione reductase activity, but the highest superoxide dismutase activity, stomatal conductance and electrolyte leakage. Microbial activities irrespective of the microbial origin seem to be coordinately functioning in the plant as an adaptive response to modulated water stress tolerance and minimizing the stress damage. The autochthonous AM fungi with Bt or Psp and those allochthonous Ri with Bm or Psp inoculants increased water stress alleviation. The autochthonous Bt showed the greatest ability to survive under high osmotic stress compared to the allochthonous strains, but when single inoculated or associated with Ri or AM fungi were similarly efficient in terms of physiological and nutritional status and in increasing plant drought tolerance, attenuating and compensating for the detrimental effect of water limitation. Copyright © 2014 Elsevier GmbH. All rights reserved.
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Physiological response to drought in radiata pine: phytohormone implication at leaf level.
De Diego, N; Pérez-Alfocea, F; Cantero, E; Lacuesta, M; Moncaleán, P
2012-04-01
Pinus radiata D. Don is one of the most abundant species in the north of Spain. Knowledge of drought response mechanisms is essential to guarantee plantation survival under reduced water supply as predicted in the future. Tolerance mechanisms are being studied in breeding programs, because information on such mechanisms can be used for genotype selection. In this paper, we analyze the changes of leaf water potential, hydraulic conductance (K(leaf)), stomatal conductance and phytohormones under drought in P. radiata breeds (O1, O2, O3, O4, O5 and O6) from different climatology areas, hypothesizing that they could show variable drought tolerance. As a primary signal, drought decreased cytokinin (zeatin and zeatin riboside-Z + ZR) levels in needles parallel to K(leaf) and gas exchange. When Z + ZR decreased by 65%, indole-3-acetic acid (IAA) and abscisic acid (ABA) accumulation started as a second signal and increments were higher for IAA than for ABA. When plants decreased by 80%, Z + ZR and K(leaf) doubled their ABA and IAA levels, the photosystem II yield decreased and the electrolyte leakage increased. At the end of the drought period, less tolerant breeds increased IAA over 10-fold compared with controls. External damage also induced jasmonic acid accumulation in all breeds except in O5 (P. radiata var. radiata × var. cedrosensis), which accumulated salicylic acid as a defense mechanism. After rewatering, only the most tolerant plants recovered their K(leaf,) perhaps due to an IAA decrease and 1-aminocyclopropane-1-carboxylic acid maintenance. From all phytohormones, IAA was the most representative 'water deficit signal' in P. radiata.
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Ren, Shuxin; Lyle, Chimera; Jiang, Guo-Liang; Penumala, Abhishek
2016-01-01
Abiotic stresses, including high soil salinity, significantly reduce crop production worldwide. Salt tolerance in plants is a complex trait and is regulated by multiple mechanisms. Understanding the mechanisms and dissecting the components on their regulatory pathways will provide new insights, leading to novel strategies for the improvement of salt tolerance in agricultural and economic crops of importance. Here we report that soybean salt tolerance 1, named GmST1, exhibited strong tolerance to salt stress in the Arabidopsis transgenic lines. The GmST1-overexpressed Arabidopsis also increased sensitivity to ABA and decreased production of reactive oxygen species under salt stress. In addition, GmST1 significantly improved drought tolerance in Arabidopsis transgenic lines. GmST1 belongs to a 3-prime part of Glyma.03g171600 gene in the current version of soybean genome sequence annotation. However, comparative reverse transcription-polymerase chain reaction analysis around Glyma.03g171600 genomic region confirmed that GmST1 might serve as an intact gene in soybean leaf tissues. Unlike Glyma.03g171600 which was not expressed in leaves, GmST1 was strongly induced by salt treatment in the leaf tissues. By promoter analysis, a TATA box was detected to be positioned close to GmST1 start codon and a putative ABRE and a DRE cis-acting elements were identified at about 1 kb upstream of GmST1 gene. The data also indicated that GmST1-transgenic lines survived under drought stress and showed a significantly lower water loss than non-transgenic lines. In summary, our results suggest that overexpression of GmST1 significantly improves Arabidopsis tolerance to both salt and drought stresses and the gene may be a potential candidate for genetic engineering of salt- and drought-tolerant crops.
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Anderegg, Leander D L; HilleRisLambers, Janneke
2016-03-01
Range shifts are among the most ubiquitous ecological responses to anthropogenic climate change and have large consequences for ecosystems. Unfortunately, the ecophysiological forces that constrain range boundaries are poorly understood, making it difficult to mechanistically project range shifts. To explore the physiological mechanisms by which drought stress controls dry range boundaries in trees, we quantified elevational variation in drought tolerance and in drought avoidance-related functional traits of a widespread gymnosperm (ponderosa pine - Pinus ponderosa) and angiosperm (trembling aspen - Populus tremuloides) tree species in the southwestern USA. Specifically, we quantified tree-to-tree variation in growth, water stress (predawn and midday xylem tension), drought avoidance traits (branch conductivity, leaf/needle size, tree height, leaf area-to-sapwood area ratio), and drought tolerance traits (xylem resistance to embolism, hydraulic safety margin, wood density) at the range margins and range center of each species. Although water stress increased and growth declined strongly at lower range margins of both species, ponderosa pine and aspen showed contrasting patterns of clinal trait variation. Trembling aspen increased its drought tolerance at its dry range edge by growing stronger but more carbon dense branch and leaf tissues, implying an increased cost of growth at its range boundary. By contrast, ponderosa pine showed little elevational variation in drought-related traits but avoided drought stress at low elevations by limiting transpiration through stomatal closure, such that its dry range boundary is associated with limited carbon assimilation even in average climatic conditions. Thus, the same climatic factor (drought) may drive range boundaries through different physiological mechanisms - a result that has important implications for process-based modeling approaches to tree biogeography. Further, we show that comparing intraspecific patterns of trait variation across ranges, something rarely done in a range-limit context, helps elucidate a mechanistic understanding of range constraints. © 2015 John Wiley & Sons Ltd.
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Ethanol accumulation in drought-stressed conifer seedlings
Daniel K. Manter; Rick G. Kelsey
2008-01-01
In this study, we investigated the effect of drought stress on ethanol production and accumulation in tissues from seedlings of three conifers (Douglas-fir, lodgepole pine, and ponderosa pine) with increasing degrees of tolerance to drought stress. Significant ethanol accumulation was only observed in their aerial tissues when severely stressed (water potential
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Evaluation of peanut cultivars, wild species, and experimental lines for drought and heat tolerance
USDA-ARS?s Scientific Manuscript database
Peanut (Arachis hypogea) is an important crop grown worldwide for its nutritional value and economic significance. Although the demand for peanuts remains high, increasing drought episodes, combined with high temperatures, threaten the supply. Peanut plants are most sensitive to drought and heat str...
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-07-27
... Determination of Nonregulated Status for Corn Genetically Engineered for Drought Tolerance AGENCY: Animal and... nonregulated status for corn designated as MON 87460, which has been genetically engineered for drought... nonregulated status for corn designated as MON 87460, which has been genetically engineered for drought...
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Physiological and Proteomic Adaptation of the Alpine Grass Stipa purpurea to a Drought Gradient
Yang, Yunqiang; Dong, Chao; Yang, Shihai; Li, Xiong; Sun, Xudong; Yang, Yongping
2015-01-01
Stipa purpurea, an endemic forage species on the Tibetan Plateau, is highly resistant to cold and drought, but the mechanisms underlying its responses to drought stress remain elusive. An understanding of such mechanisms may be useful for developing cultivars that are adaptable to water deficit. In this study, we analyzed the physiological and proteomic responses of S. purpurea under increasing drought stress. Seedlings of S. purpurea were subjected to a drought gradient in a controlled experiment, and proteins showing changes in abundance under these conditions were identified by two-dimensional electrophoresis followed by mass spectrometry analysis. A western blotting analysis was conducted to confirm the increased abundance of a heat-shock protein, NCED2, and a dehydrin in S. purpurea seedlings under drought conditions. We detected carbonylated proteins to identify oxidation-sensitive proteins in S. purpurea seedlings, and found that ribulose-1, 5-bisphosphate carboxylase oxygenase (RuBisCO) was one of the oxidation-sensitive proteins under drought. Together, these results indicated drought stress might inhibit photosynthesis in S. purpurea by oxidizing RuBisCO, but the plants were able to maintain photosynthetic efficiency by a compensatory upregulation of unoxidized RuBisCO and other photosynthesis-related proteins. Further analyses confirmed that increased abundance of antioxidant enzymes could balance the redox status of the plants to mitigate drought-induced oxidative damage. PMID:25646623
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Effect of water availability on tolerance of leaf damage in tall morning glory, Ipomoea purpurea
NASA Astrophysics Data System (ADS)
Atala, Cristian; Gianoli, Ernesto
2009-03-01
Resource availability may limit plant tolerance of herbivory. To predict the effect of differential resource availability on plant tolerance, the limiting resource model (LRM) considers which resource limits plant fitness and which resource is mostly affected by herbivore damage. We tested the effect of experimental drought on tolerance of leaf damage in Ipomoea purpurea, which is naturally exposed to both leaf damage and summer drought. To seek mechanistic explanations, we also measured several morphological, allocation and gas exchange traits. In this case, LRM predicts that tolerance would be the same in both water treatments. Plants were assigned to a combination of two water treatments (control and low water) and two damage treatments (50% defoliation and undamaged). Plants showed tolerance of leaf damage, i.e., a similar number of fruits were produced by damaged and undamaged plants, only in control water. Whereas experimental drought affected all plant traits, leaf damage caused plants to show a greater leaf trichome density and reduced shoot biomass, but only in low water. It is suggested that the reduced fitness (number of fruits) of damaged plants in low water was mediated by the differential reduction of shoot biomass, because the number of fruits per shoot biomass was similar in damaged and undamaged plants. Alternative but less likely explanations include the opposing direction of functional responses to drought and defoliation, and resource costs of the damage-induced leaf trichome density. Our results somewhat challenge the LRM predictions, but further research including field experiments is needed to validate some of the preliminary conclusions drawn.
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Water availability limits tolerance of apical damage in the Chilean tarweed Madia sativa
NASA Astrophysics Data System (ADS)
Gonzáles, Wilfredo L.; Suárez, Lorena H.; Molina-Montenegro, Marco A.; Gianoli, Ernesto
2008-07-01
Plant tolerance is the ability to reduce the negative impact of herbivory on plant fitness. Numerous studies have shown that plant tolerance is affected by nutrient availability, but the effect of soil moisture has received less attention. We evaluated tolerance of apical damage (clipping that mimicked insect damage) under two watering regimes (control watering and drought) in the tarweed Madia sativa (Asteraceae). We recorded number of heads with seeds and total number of heads as traits related to fitness. Net photosynthetic rate, water use efficiency, number of branches, shoot biomass, and the root:shoot biomass ratio were measured as traits potentially related to tolerance via compensatory responses to damage. In the drought treatment, damaged plants showed ≈43% reduction in reproductive fitness components in comparison with undamaged plants. In contrast, there was no significant difference in reproductive fitness between undamaged and damaged plants in the control watering treatment. Shoot biomass was not affected by apical damage. The number of branches increased after damage in both water treatments but this increase was limited by drought stress. Net photosynthetic rate increased in damaged plants only in the control watering treatment. Water use efficiency increased with drought stress and, in plants regularly watered, also increased after damage. Root:shoot ratio was higher in the low water treatment and damaged plants tended to reduce root:shoot ratio only in this water treatment. It is concluded that water availability limits tolerance to apical damage in M. sativa, and that putative compensatory mechanisms are differentially affected by water availability.
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Valluru, Ravi; Davies, William J.; Reynolds, Matthew P.; Dodd, Ian C.
2016-01-01
Although, plant hormones play an important role in adjusting growth in response to environmental perturbation, the relative contributions of abscisic acid (ABA) and ethylene remain elusive. Using six spring wheat genotypes differing for stress tolerance, we show that young seedlings of the drought-tolerant (DT) group maintained or increased shoot dry weight (SDW) while the drought-susceptible (DS) group decreased SDW in response to mild drought. Both the DT and DS groups increased endogenous ABA and ethylene concentrations under mild drought compared to control. The DT and DS groups exhibited different SDW response trends, whereby the DS group decreased while the DT group increased SDW, to increased concentrations of ABA and ethylene under mild drought, although both groups decreased ABA/ethylene ratio under mild drought albeit at different levels. We concluded that SDW of the DT and DS groups might be distinctly regulated by specific ABA:ethylene ratio. Further, a foliar-spray of low concentrations (0.1 μM) of ABA increased shoot relative growth rate (RGR) in the DS group while ACC (1-aminocyclopropane-1-carboxylic acid, ethylene precursor) spray increased RGR in both groups compared to control. Furthermore, the DT group accumulated a significantly higher galactose while a significantly lower maltose in the shoot compared to the DS group. Taken all together, these results suggest an impact of ABA, ethylene, and ABA:ethylene ratio on SDW of wheat seedlings that may partly underlie a genotypic variability of different shoot growth sensitivities to drought among crop species under field conditions. We propose that phenotyping based on hormone accumulation, response and hormonal ratio would be a viable, rapid, and an early–stage selection tool aiding genotype selection for stress tolerance. PMID:27148292
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Kiranmai, Kurnool; Lokanadha Rao, Gunupuru; Pandurangaiah, Merum; Nareshkumar, Ambekar; Amaranatha Reddy, Vennapusa; Lokesh, Uppala; Venkatesh, Boya; Anthony Johnson, A M; Sudhakar, Chinta
2018-01-01
Drought stress has adverse effects on growth, water relations, photosynthesis and yield of groundnut. WRKY transcription factors (TFs) are the plant-specific TFs which regulate several down-stream stress-responsive genes and play an essential role in plant biotic and abiotic stress responses. We found that WRKY3 gene is highly up-regulated under drought stress conditions and therefore isolated a new WRKY3TF gene from a drought-adapted horsegram ( Macrotyloma uniflorum Lam. Verdc.). Conserved domain studies revealed that protein encoded by this gene contains highly conserved regions of two WRKY domains and two C2H2 zinc-finger motifs. The fusion protein localization studies of transient MuWRKY 3-YFP revealed its nuclear localization. Overexpression of MuWRKY3 TF gene in groundnut ( Arachis hypogaea L.) showed increased tolerance to drought stress compared to wild-type (WT) plants. MuWRKY3 groundnut transgenics displayed lesser and delayed wilting symptoms than WT plants after 10-days of drought stress imposition. The transgenic groundnut plants expressing MuWRKY3 showed less accumulation of malondialdehyde, hydrogen peroxide (H 2 O 2 ), and superoxide anion (O 2 ∙- ), accompanied by more free proline, total soluble sugar content, and activities of antioxidant enzymes than WT plants under drought stress. Moreover, a series of stress-related LEA, HSP, MIPS, APX, SOD , and CAT genes found up-regulated in the transgenic groundnut plants. The study demonstrates that nuclear-localized MuWRKY3 TF regulates the expression of stress-responsive genes and the activity of ROS scavenging enzymes which results in improved drought tolerance in groundnut. We conclude that MuWRKY3 may serve as a new putative candidate gene for the improvement of stress resistance in plants.
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Kiranmai, Kurnool; Lokanadha Rao, Gunupuru; Pandurangaiah, Merum; Nareshkumar, Ambekar; Amaranatha Reddy, Vennapusa; Lokesh, Uppala; Venkatesh, Boya; Anthony Johnson, A. M.; Sudhakar, Chinta
2018-01-01
Drought stress has adverse effects on growth, water relations, photosynthesis and yield of groundnut. WRKY transcription factors (TFs) are the plant-specific TFs which regulate several down-stream stress-responsive genes and play an essential role in plant biotic and abiotic stress responses. We found that WRKY3 gene is highly up-regulated under drought stress conditions and therefore isolated a new WRKY3TF gene from a drought-adapted horsegram (Macrotyloma uniflorum Lam. Verdc.). Conserved domain studies revealed that protein encoded by this gene contains highly conserved regions of two WRKY domains and two C2H2 zinc-finger motifs. The fusion protein localization studies of transient MuWRKY3-YFP revealed its nuclear localization. Overexpression of MuWRKY3 TF gene in groundnut (Arachis hypogaea L.) showed increased tolerance to drought stress compared to wild-type (WT) plants. MuWRKY3 groundnut transgenics displayed lesser and delayed wilting symptoms than WT plants after 10-days of drought stress imposition. The transgenic groundnut plants expressing MuWRKY3 showed less accumulation of malondialdehyde, hydrogen peroxide (H2O2), and superoxide anion (O2∙-), accompanied by more free proline, total soluble sugar content, and activities of antioxidant enzymes than WT plants under drought stress. Moreover, a series of stress-related LEA, HSP, MIPS, APX, SOD, and CAT genes found up-regulated in the transgenic groundnut plants. The study demonstrates that nuclear-localized MuWRKY3 TF regulates the expression of stress-responsive genes and the activity of ROS scavenging enzymes which results in improved drought tolerance in groundnut. We conclude that MuWRKY3 may serve as a new putative candidate gene for the improvement of stress resistance in plants. PMID:29616059
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High-Throughput Phenotyping to Detect Drought Tolerance QTL in Wild Barley Introgression Lines
Honsdorf, Nora; March, Timothy John; Berger, Bettina; Tester, Mark; Pillen, Klaus
2014-01-01
Drought is one of the most severe stresses, endangering crop yields worldwide. In order to select drought tolerant genotypes, access to exotic germplasm and efficient phenotyping protocols are needed. In this study the high-throughput phenotyping platform “The Plant Accelerator”, Adelaide, Australia, was used to screen a set of 47 juvenile (six week old) wild barley introgression lines (S42ILs) for drought stress responses. The kinetics of growth development was evaluated under early drought stress and well watered treatments. High correlation (r = 0.98) between image based biomass estimates and actual biomass was demonstrated, and the suitability of the system to accurately and non-destructively estimate biomass was validated. Subsequently, quantitative trait loci (QTL) were located, which contributed to the genetic control of growth under drought stress. In total, 44 QTL for eleven out of 14 investigated traits were mapped, which for example controlled growth rate and water use efficiency. The correspondence of those QTL with QTL previously identified in field trials is shown. For instance, six out of eight QTL controlling plant height were also found in previous field and glasshouse studies with the same introgression lines. This indicates that phenotyping juvenile plants may assist in predicting adult plant performance. In addition, favorable wild barley alleles for growth and biomass parameters were detected, for instance, a QTL that increased biomass by approximately 36%. In particular, introgression line S42IL-121 revealed improved growth under drought stress compared to the control Scarlett. The introgression line showed a similar behavior in previous field experiments, indicating that S42IL-121 may be an attractive donor for breeding of drought tolerant barley cultivars. PMID:24823485
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De Diego, N; Saiz-Fernández, I; Rodríguez, J L; Pérez-Alfocea, P; Sampedro, M C; Barrio, R J; Lacuesta, M; Moncaleán, P
2015-09-01
Studies of metabolic and physiological bases of plant tolerance and hardening against drought are essential to improve genetic breeding programs, especially in productive species such as Pinus radiata. The exposure to different drought cycles is a highly effective tool that improves plant conditioning, but limited information is available about the mechanisms that modulate this process. To clarify this issue, six P. radiata breeds with well-known differences in drought tolerance were analyzed after two consecutive drought cycles. Survival rate, concentration of several metabolites such as free soluble amino acids and polyamines, and main plant hormones varied between them after drought hardening, while relative growth ratio and water potential at both predawn and dawn did not. Hardening induced a strong increase in total soluble amino acids in all breeds, accumulating mainly those implicated in the glutamate metabolism (GM), especially L-proline, in the most tolerant breeds. Other amino acids from GM such as γ-aminobutyric acid (GABA) and L-arginine (Arg) were also strongly increased. GABA pathway could improve the response against drought, whereas Arg acts as precursor for the synthesis of spermidine. This polyamine showed a positive relationship with the survival capacity, probably due to its role as antioxidant under stress conditions. Finally, drought hardening also induced changes in phytohormone content, showing each breed a different profile. Although all of them accumulated indole-3-acetic acid and jasmonic acid and reduced zeatin content in needles, significant differences were observed regarding abscisic acid, salicylic acid and mainly zeatin riboside. These results confirm that hardening is not only species-dependent but also an intraspecific processes controlled through metabolite changes. Copyright © 2015 Elsevier GmbH. All rights reserved.
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Shrubland primary production and soil respiration diverge along European climate gradient
Reinsch, Sabine; Koller, Eva; Sowerby, Alwyn; de Dato, Giovanbattista; Estiarte, Marc; Guidolotti, Gabriele; Kovács-Láng, Edit; Kröel-Dulay, György; Lellei-Kovács, Eszter; Larsen, Klaus S.; Liberati, Dario; Peñuelas, Josep; Ransijn, Johannes; Robinson, David A.; Schmidt, Inger K.; Smith, Andrew R.; Tietema, Albert; Dukes, Jeffrey S.; Beier, Claus; Emmett, Bridget A.
2017-01-01
Above- and belowground carbon (C) stores of terrestrial ecosystems are vulnerable to environmental change. Ecosystem C balances in response to environmental changes have been quantified at individual sites, but the magnitudes and directions of these responses along environmental gradients remain uncertain. Here we show the responses of ecosystem C to 8–12 years of experimental drought and night-time warming across an aridity gradient spanning seven European shrublands using indices of C assimilation (aboveground net primary production: aNPP) and soil C efflux (soil respiration: Rs). The changes of aNPP and Rs in response to drought indicated that wet systems had an overall risk of increased loss of C but drier systems did not. Warming had no consistent effect on aNPP across the climate gradient, but suppressed Rs more at the drier sites. Our findings suggest that above- and belowground C fluxes can decouple, and provide no evidence of acclimation to environmental change at a decadal timescale. aNPP and Rs especially differed in their sensitivity to drought and warming, with belowground processes being more sensitive to environmental change. PMID:28256623
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Shrubland primary production and soil respiration diverge along European climate gradient
NASA Astrophysics Data System (ADS)
Reinsch, Sabine; Koller, Eva; Sowerby, Alwyn; de Dato, Giovanbattista; Estiarte, Marc; Guidolotti, Gabriele; Kovács-Láng, Edit; Kröel-Dulay, György; Lellei-Kovács, Eszter; Larsen, Klaus S.; Liberati, Dario; Peñuelas, Josep; Ransijn, Johannes; Robinson, David A.; Schmidt, Inger K.; Smith, Andrew R.; Tietema, Albert; Dukes, Jeffrey S.; Beier, Claus; Emmett, Bridget A.
2017-03-01
Above- and belowground carbon (C) stores of terrestrial ecosystems are vulnerable to environmental change. Ecosystem C balances in response to environmental changes have been quantified at individual sites, but the magnitudes and directions of these responses along environmental gradients remain uncertain. Here we show the responses of ecosystem C to 8-12 years of experimental drought and night-time warming across an aridity gradient spanning seven European shrublands using indices of C assimilation (aboveground net primary production: aNPP) and soil C efflux (soil respiration: Rs). The changes of aNPP and Rs in response to drought indicated that wet systems had an overall risk of increased loss of C but drier systems did not. Warming had no consistent effect on aNPP across the climate gradient, but suppressed Rs more at the drier sites. Our findings suggest that above- and belowground C fluxes can decouple, and provide no evidence of acclimation to environmental change at a decadal timescale. aNPP and Rs especially differed in their sensitivity to drought and warming, with belowground processes being more sensitive to environmental change.
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Yang, Tongren; Yao, Sufei; Hao, Lin; Zhao, Yuanyuan; Lu, Wenjing; Xiao, Kai
2016-11-01
Wheat bHLH family gene TabHLH1 is responsive to drought and salt stresses, and it acts as one crucial regulator in mediating tolerance to aforementioned stresses largely through an ABA-associated pathway. Osmotic stresses are adverse factors for plant growth and crop productivity. In this study, we characterized TabHLH1, a gene encoding wheat bHLH-type transcription factor (TF) protein, in mediating plant adaptation to osmotic stresses. TabHLH1 protein contains a conserved basic-helix-loop-helix (bHLH) domain shared by its plant counterparts. Upon PEG-simulated drought stress, salt stress, and exogenous abscisic acid (ABA), the TabHLH1 transcripts in roots and leaves were induced. Under PEG-simulated drought stress and salt stress treatments, the tobacco seedlings with TabHLH1 overexpression exhibited improved growth and osmotic stress-associated traits, showing increased biomass and reduced leaf water loss rate (WLR) relative to wild type (WT). The transgenic lines also possessed promoted stomata closure under drought stress, salt stress, and exogenous ABA and increased proline and soluble sugar contents and reduced hydrogen peroxide (H 2 O 2 ) amount under osmotic stress conditions, indicating that TabHLH1-mediated osmolyte accumulation and cellular ROS homeostasis contributed to the drought stress and salt stress tolerance. NtPYL12 and NtSAPK2;1, the genes encoding ABA receptor and SnRK2 family kinase, respectively, showed up-regulated expression in lines overexpressing TabHLH1 under osmotic stress and exogenous ABA conditions; overexpression of them conferred plants modified stomata movement, leaf WLR, and growth feature under drought and high salinity, suggesting that these ABA-signaling genes are mediated by wheat TabHLH1 gene and involved in regulating plant responses to simulated drought and salt stresses. Our investigation indicates that the TabHLH1 gene plays critical roles in plant tolerance to osmotic stresses largely through an ABA-dependent pathway.
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Rivas, Rebeca; Oliveira, Marciel T; Santos, Mauro G
2013-02-01
The main objective of this study was to assess whether recurring water stress occurring from seed germination to young plants of Moringa oleifera Lam. are able to mitigate the drought stress effects. Germination, gas exchange and biochemical parameters were analysed after three cycles of water deficit. Young plants were used 50 days after germination under three osmotic potentials (0.0, -0.3 and -0.4 MPa). For each germination treatment, control (irrigated) and stressed (10% of water control) plants were compared for a total of six treatments. There were two cycles of drought interspersed with 10 days of rehydration. The young plants of M. oleifera showed increased tolerance to repeated cycles of drought, maintaining high relative water content (RWC), high water use efficiency (WUE), increased photosynthetic pigments and increased activity of antioxidant enzymes. There was rapid recovery of the photosynthetic rate during the rehydration period. The stressed plants from the -0.3 and -0.4 MPa treatments showed higher tolerance compared to the control plants. The results suggest that seeds of M. oleifera subjected to mild water deficit have had increased the ability for drought tolerance when young plant. Copyright © 2012 Elsevier Masson SAS. All rights reserved.
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Modise, David M.; Gemeildien, Junaid; Ndimba, Bongani K.; Christoffels, Alan
2018-01-01
Background Crop response to the changing climate and unpredictable effects of global warming with adverse conditions such as drought stress has brought concerns about food security to the fore; crop yield loss is a major cause of concern in this regard. Identification of genes with multiple responses across environmental stresses is the genetic foundation that leads to crop adaptation to environmental perturbations. Methods In this paper, we introduce an integrated approach to assess candidate genes for multiple stress responses across-species. The approach combines ontology based semantic data integration with expression profiling, comparative genomics, phylogenomics, functional gene enrichment and gene enrichment network analysis to identify genes associated with plant stress phenotypes. Five different ontologies, viz., Gene Ontology (GO), Trait Ontology (TO), Plant Ontology (PO), Growth Ontology (GRO) and Environment Ontology (EO) were used to semantically integrate drought related information. Results Target genes linked to Quantitative Trait Loci (QTLs) controlling yield and stress tolerance in sorghum (Sorghum bicolor (L.) Moench) and closely related species were identified. Based on the enriched GO terms of the biological processes, 1116 sorghum genes with potential responses to 5 different stresses, such as drought (18%), salt (32%), cold (20%), heat (8%) and oxidative stress (25%) were identified to be over-expressed. Out of 169 sorghum drought responsive QTLs associated genes that were identified based on expression datasets, 56% were shown to have multiple stress responses. On the other hand, out of 168 additional genes that have been evaluated for orthologous pairs, 90% were conserved across species for drought tolerance. Over 50% of identified maize and rice genes were responsive to drought and salt stresses and were co-located within multifunctional QTLs. Among the total identified multi-stress responsive genes, 272 targets were shown to be co-localized within QTLs associated with different traits that are responsive to multiple stresses. Ontology mapping was used to validate the identified genes, while reconstruction of the phylogenetic tree was instrumental to infer the evolutionary relationship of the sorghum orthologs. The results also show specific genes responsible for various interrelated components of drought response mechanism such as drought tolerance, drought avoidance and drought escape. Conclusions We submit that this approach is novel and to our knowledge, has not been used previously in any other research; it enables us to perform cross-species queries for genes that are likely to be associated with multiple stress tolerance, as a means to identify novel targets for engineering stress resistance in sorghum and possibly, in other crop species. PMID:29590108
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Spatial Configuration of Drought Disturbance and Forest Gap Creation across Environmental Gradients
Andrew, Margaret E.; Ruthrof, Katinka X.; Matusick, George; Hardy, Giles E. St. J.
2016-01-01
Climate change is increasing the risk of drought to forested ecosystems. Although drought impacts are often anecdotally noted to occur in discrete patches of high canopy mortality, the landscape effects of drought disturbances have received virtually no study. This study characterized the landscape configuration of drought impact patches and investigated the relationships between patch characteristics, as indicators of drought impact intensity, and environmental gradients related to water availability to determine factors influencing drought vulnerability. Drought impact patches were delineated from aerial surveys following an extreme drought in 2011 in southwestern Australia, which led to patchy canopy dieback of the Northern Jarrah Forest, a Mediterranean forest ecosystem. On average, forest gaps produced by drought-induced dieback were moderate in size (6.6 ± 9.7 ha, max = 85.7 ha), compact in shape, and relatively isolated from each other at the scale of several kilometers. However, there was considerable spatial variation in the size, shape, and clustering of forest gaps. Drought impact patches were larger and more densely clustered in xeric areas, with significant relationships observed with topographic wetness index, meteorological variables, and stand height. Drought impact patch clustering was more strongly associated with the environmental factors assessed (R2 = 0.32) than was patch size (R2 = 0.21); variation in patch shape remained largely unexplained (R2 = 0.02). There is evidence that the xeric areas with more intense drought impacts are ‘chronic disturbance patches’ susceptible to recurrent drought disturbance. The spatial configuration of drought disturbances is likely to influence ecological processes including forest recovery and interacting disturbances such as fire. Regime shifts to an alternate, non-forested ecosystem may occur preferentially in areas with large or clustered drought impact patches. Improved understanding of drought impacts and their patterning in space and time will expand our knowledge of forest ecosystems and landscape processes, informing management of these dynamic systems in an uncertain future. PMID:27275744
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Gašparič, Meti Buh; Lenassi, Metka; Gostinčar, Cene; Rotter, Ana; Plemenitaš, Ana; Gunde-Cimerman, Nina; Gruden, Kristina; Zel, Jana
2013-01-01
Soil salinity and drought are among the most serious agricultural and environmental problems of today. Therefore, investigations of plant resistance to abiotic stress have received a lot of attention in recent years. In this study, we identified the complete coding sequence of a 3'-phosphoadenosine-5'-phosphatase protein, ApHal2, from the halotolerant yeast Aureobasidium pullulans. Expression of the ApHAL2 gene in a Saccharomyces cerevisiae hal2 mutant complemented the mutant auxotrophy for methionine, and rescued the growth of the hal2 mutant in media with high NaCl concentrations. A 21-amino-acids-long region of the ApHal2 enzyme was inserted into the Arabidopsis thaliana homologue of Hal2, the SAL1 phosphatase. The inserted sequence included the META motif, which has previously been implicated in increased sodium tolerance of the Hal2 homologue from a related fungal species. Transgenic Arabidopsis plants overexpressing this modified SAL1 (mSAL1) showed improved halotolerance and drought tolerance. In a medium with an elevated salt concentration, mSAL1-expressing plants were twice as likely to have roots in a higher length category in comparison with the wild-type Arabidopsis and with plants overexpressing the native SAL1, and had 5% to 10% larger leaf surface area under moderate and severe salt stress, respectively. Similarly, after moderate drought exposure, the mSAL1-expressing plants showed 14% increased dry weight after revitalisation, with no increase in dry weight of the wild-type plants. With severe drought, plants overexpressing native SAL1 had the worst rehydration success, consistent with the recently proposed role of SAL1 in severe drought. This was not observed for plants expressing mSAL1. Therefore, the presence of this fungal META motif sequence is beneficial under conditions of increased salinity and moderate drought, and shows no drawbacks for plant survival under severe drought. This demonstrates that adaptations of extremotolerant fungi should be considered as a valuable resource for improving stress-tolerance in plant breeding in the future.
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Wheat TaPUB1 modulates plant drought stress resistance by improving antioxidant capability.
Zhang, Guangqiang; Zhang, Meng; Zhao, Zhongxian; Ren, Yuanqing; Li, Qinxue; Wang, Wei
2017-08-08
E3 ligases play significant roles in plant stress tolerance by targeting specific substrate proteins for post-translational modification. In a previous study, we cloned TaPUB1 from Triticum aestivum L., which encodes a U-box E3 ligase. Real-time polymerase chain reaction revealed that the gene was up-regulated under drought stress. To investigate the function of TaPUB1 in the response of plants to drought, we generated transgenic Nicotiana benthamiana (N. benthamiana) plants constitutively expressing TaPUB1 under the CaMV35S promoter. Compared to wild type (WT), the transgenic plants had higher germination and seedling survival rates as well as higher photosynthetic rate and water retention, suggesting that the overexpression of TaPUB1 enhanced the drought tolerance of the TaPUB1 overexpressing (OE) plants. Moreover, less accumulation of reactive oxygen species (ROS) and stronger antioxidant capacity were detected in the OE plants than in the WT plants. To characterize the mechanisms involved, methyl viologen (MV) was used to induce oxidative stress conditions and we identified the functions of this gene in the plant tolerance to oxidative stress. Our results suggest that TaPUB1 positively modulates plant drought stress resistance potential by improving their antioxidant capacity.
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What mediates tree mortality during drought in the southern Sierra Nevada?
Paz-Kagan, Tarin; Brodrick, Philip; Vaughn, Nicholas R.; Das, Adrian J.; Stephenson, Nathan L.; Nydick, Koren R.; Asner, Gregory P.
2017-01-01
Severe drought has the potential to cause selective mortality within a forest, thereby inducing shifts in forest species composition. The southern Sierra Nevada foothills and mountains of California have experienced extensive forest dieback due to drought stress and insect outbreak. We used high-fidelity imaging spectroscopy (HiFIS) and light detection and ranging (LiDAR) from the Carnegie Airborne Observatory (CAO) to estimate the effect of forest dieback on species composition in response to drought stress in Sequoia National Park. Our aims were: (1) to quantify site-specific conditions that mediate tree mortality along an elevation gradient in the southern Sierra Nevada Mountains; (2) to assess where mortality events have a greater probability of occurring; and (3) to estimate which tree species have a greater likelihood of mortality along the elevation gradient. A series of statistical models were generated to classify species composition and identify tree mortality, and the influences of different environmental factors were spatially quantified and analyzed to assess where mortality events have a greater likelihood of occurring. A higher probability of mortality was observed in the lower portion of the elevation gradient, on southwest and west-facing slopes, in areas with shallow soils, on shallower slopes, and at greater distances from water. All of these factors are related to site water balance throughout the landscape. Our results also suggest that mortality is species-specific along the elevation gradient, mainly affecting Pinus ponderosa and Pinus lambertiana at lower elevations. Selective mortality within the forest may drive long-term shifts in community composition along the elevation gradient.
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What mediates tree mortality during drought in the southern Sierra Nevada?
Paz-Kagan, Tarin; Brodrick, Philip G; Vaughn, Nicholas R; Das, Adrian J; Stephenson, Nathan L; Nydick, Koren R; Asner, Gregory P
2017-12-01
Severe drought has the potential to cause selective mortality within a forest, thereby inducing shifts in forest species composition. The southern Sierra Nevada foothills and mountains of California have experienced extensive forest dieback due to drought stress and insect outbreak. We used high-fidelity imaging spectroscopy (HiFIS) and light detection and ranging (LiDAR) from the Carnegie Airborne Observatory (CAO) to estimate the effect of forest dieback on species composition in response to drought stress in Sequoia National Park. Our aims were (1) to quantify site-specific conditions that mediate tree mortality along an elevation gradient in the southern Sierra Nevada Mountains, (2) to assess where mortality events have a greater probability of occurring, and (3) to estimate which tree species have a greater likelihood of mortality along the elevation gradient. A series of statistical models were generated to classify species composition and identify tree mortality, and the influences of different environmental factors were spatially quantified and analyzed to assess where mortality events have a greater likelihood of occurring. A higher probability of mortality was observed in the lower portion of the elevation gradient, on southwest- and west-facing slopes, in areas with shallow soils, on shallower slopes, and at greater distances from water. All of these factors are related to site water balance throughout the landscape. Our results also suggest that mortality is species-specific along the elevation gradient, mainly affecting Pinus ponderosa and Pinus lambertiana at lower elevations. Selective mortality within the forest may drive long-term shifts in community composition along the elevation gradient. © 2017 by the Ecological Society of America.
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Cabello, Julieta V; Giacomelli, Jorge I; Gómez, María C; Chan, Raquel L
2017-09-10
Homeodomain-leucine zipper (HD-Zip) transcription factors are unique to the plant kingdom; members of subfamily I are known to be involved in abiotic stress responses. HaHB11 belongs to this subfamily and it was previously shown that it is able to confer improved yield and tolerance to flooding via a quiescent strategy. Here we show that HaHB11 expression is induced by ABA, NaCl and water deficit in sunflower seedlings and leaves. Arabidopsis transgenic plants expressing HaHB11, controlled either by its own promoter or by the constitutive 35S CaMV, presented rolled leaves and longer roots than WT when grown under standard conditions. In addition, these plants showed wider stems and more vascular bundles. To deal with drought, HaHB11 transgenic plants closed their stomata faster and lost less water than controls, triggering an enhanced tolerance to such stress condition and also to salinity stress. Concomitantly, ABA-synthesis and sensing related genes were differentially regulated in HaHB11 transgenic plants. Either under long-term salinity stress or mild drought stress, HaHB11 transgenic plants did not exhibit yield penalties. Moreover, alfalfa transgenic plants were generated which also showed enhanced drought tolerance. Altogether, the results indicated that HaHB11 was able to confer drought and salinity tolerance via a complex mechanism which involves morphological, physiological and molecular changes. Copyright © 2016 Elsevier B.V. All rights reserved.
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USDA-ARS?s Scientific Manuscript database
Drought is the major abiotic stress limiting crop production. Plant cuticle represents the outer-most layer of the epidermis and previous studies demonstrate its association with plant response to climatological drought. We report here the functional characterization of the rice ((Oryza sativa L.) W...
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Garg, Rohini; Shankar, Rama; Thakkar, Bijal; Kudapa, Himabindu; Krishnamurthy, Lakshmanan; Mantri, Nitin; Varshney, Rajeev K.; Bhatia, Sabhyata; Jain, Mukesh
2016-01-01
Drought and salinity are the major factors that limit chickpea production worldwide. We performed whole transcriptome analyses of chickpea genotypes to investigate the molecular basis of drought and salinity stress response/adaptation. Phenotypic analyses confirmed the contrasting responses of the chickpea genotypes to drought or salinity stress. RNA-seq of the roots of drought and salinity related genotypes was carried out under control and stress conditions at vegetative and/or reproductive stages. Comparative analysis of the transcriptomes revealed divergent gene expression in the chickpea genotypes at different developmental stages. We identified a total of 4954 and 5545 genes exclusively regulated in drought-tolerant and salinity-tolerant genotypes, respectively. A significant fraction (~47%) of the transcription factor encoding genes showed differential expression under stress. The key enzymes involved in metabolic pathways, such as carbohydrate metabolism, photosynthesis, lipid metabolism, generation of precursor metabolites/energy, protein modification, redox homeostasis and cell wall component biogenesis, were affected by drought and/or salinity stresses. Interestingly, transcript isoforms showed expression specificity across the chickpea genotypes and/or developmental stages as illustrated by the AP2-EREBP family members. Our findings provide insights into the transcriptome dynamics and components of regulatory network associated with drought and salinity stress responses in chickpea. PMID:26759178
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Jiang, Yanling; Xu, Zhenzhu; Zhou, Guangsheng; Liu, Tao
2016-07-12
The atmospheric CO2 concentration is rising continuously, and abnormal precipitation may occur more frequently in the future. Although the effects of elevated CO2 and drought on plants have been well reported individually, little is known about their interaction, particularly over a water status gradient. Here, we aimed to characterize the effects of elevated CO2 and a water status gradient on the growth, photosynthetic capacity, and mesophyll cell ultrastructure of a dominant grass from a degraded grassland. Elevated CO2 stimulated plant biomass to a greater extent under moderate changes in water status than under either extreme drought or over-watering conditions. Photosynthetic capacity and stomatal conductance were also enhanced by elevated CO2 under moderate drought, but inhibited with over-watering. Severe drought distorted mesophyll cell organelles, but CO2 enrichment partly alleviated this effect. Intrinsic water use efficiency (WUEi) and total biomass water use efficiency (WUEt) were increased by elevated CO2, regardless of water status. Plant structural traits were also found to be tightly associated with photosynthetic potentials. The results indicated that CO2 enrichment alleviated severe and moderate drought stress, and highlighted that CO2 fertilization's dependency on water status should be considered when projecting key species' responses to climate change in dry ecosystems.
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NASA Astrophysics Data System (ADS)
Mitra, B.; Basu, S.; Bereznyakov, D.; Pereira, A.; Naithani, K. J.
2015-12-01
Drought across different agro-climatic regions of the world has the capacity to drastically impact the yield potential of rice. Consequently, there is growing interest in developing drought tolerant rice varieties with high yield. We parameterized two photosynthesis models based on light and CO2 response curves for seven different rice genotypes with different drought survival mechanisms: sensitive (Nipponbar, TEJ), resistance (Bengal, TRJ), avoidance by osmotic adjustment (Kaybonnet, TRJ; IRAT177, TRJ; N22, Aus; Vandana, Aus; and O Glabberrima, 316603). All rice genotypes were grown in greenhouse conditions (24 °C ± 3°C air temperature and ~ 600 μmol m-2 s-1 light intensity) with light/dark cycles of 10/14 h in water filled trays simulating flooded conditions. Measurements were conducted on fully grown plants (35 - 60 days old) under simulated flooded and drought conditions. Preliminary results have shown that the drought sensitive genotype, Nipponbare has the lowest photosynthetic carboxylation capacity (Vcmax) and a similar electron transport rate (Jmax) compared to the drought resistant genotype IRAT 177. Mitochondrial respiration (Rd) of all the genotypes were similar while quantum yield of the drought sensitive genotype was greater than that of the drought resistant genotypes. While both drought tolerant and drought sensitive rice genotypes have the same photosynthetic yield, from an irrigation perspective the former would require less 'drop per grain'. This has enormous economic and management implications on account of dwindling water resources across the world due to drought.
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Phosphorous Application Improves Drought Tolerance of Phoebe zhennan.
Tariq, Akash; Pan, Kaiwen; Olatunji, Olusanya A; Graciano, Corina; Li, Zilong; Sun, Feng; Sun, Xiaoming; Song, Dagang; Chen, Wenkai; Zhang, Aiping; Wu, Xiaogang; Zhang, Lin; Mingrui, Deng; Xiong, Qinli; Liu, Chenggang
2017-01-01
Phoebe zhennan (Gold Phoebe) is a threatened tree species in China and a valuable and important source of wood and bioactive compounds used in medicine. Apart from anthropogenic disturbances, several biotic constraints currently restrict its growth and development. However, little attention has been given to building adaptive strategies for its conservation by examining its morphological and physio-biochemical responses to drought stress, and the role of fertilizers on these responses. A randomized experimental design was used to investigate the effects of two levels of irrigation (well-watered and drought-stressed) and phosphorous (P) fertilization treatment (with and without P) to assess the morphological and physio-biochemical responses of P. zhennan seedlings to drought stress. In addition, we evaluated whether P application could mitigate the negative impacts of drought on plant growth and metabolism. Drought stress had a significant negative effect on the growth and metabolic processes of P. zhennan . Despite this, reduced leaf area, limited stomatal conductance, reduced transpiration rate, increased water use efficiency, enhanced antioxidant enzymes activities, and osmolytes accumulation suggested that the species has good adaptive strategies for tolerating drought stress. Application of P had a significant positive effect on root biomass, signifying its improved water extracting capacity from the soil. Moreover, P fertilization significantly increased leaf relative water content, net photosynthetic rate, and maximal quantum efficiency of PSII under drought stress conditions. This may be attributable to several factors, such as enhanced root biomass, decreased malondialdehyde content, and the up-regulation of chloroplast pigments, osmolytes, and nitrogenous compounds. However, P application had only a slight or negligible effect on the growth and metabolism of well-watered plants. In conclusion, P. zhennan has a strong capability for drought resistance, while P application facilitates and improves drought tolerance mostly through physio-biochemical adjustments, regardless of water availability. It is imperative to explore the underlying metabolic mechanisms and effects of different levels of P fertilization on P. zhennan under drought conditions in order to design appropriate conservation and management strategies for this species, which is at risk of extinction.
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Method to improve drought tolerance in plants
Schroeder, Julian I.; Kwak, June Myoung
2003-10-21
A method to increase drought resistance in plants is provided. The method comprises inhibiting or disabling inward-rectifying K.sup.+ (K.sup.+.sub.in) channels in the stomatal guard cells of the plant.
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The contrasting microRNA content of a drought tolerant and a drought susceptible wheat cultivar.
Bakhshi, Behnam; Fard, Ehsan Mohseni; Gharechahi, Javad; Safarzadeh, Mahdieh; Nikpay, Nava; Fotovat, Reza; Azimi, Mohammad Reza; Salekdeh, Ghasem Hosseini
2017-09-01
Drought stress represents one of the most common stresses affecting the productivity of crop plants. A rather recently discovered component of the plant response to drought is the cellular population of microRNAs. Here, the microRNA content was revealed of two bread wheat cultivars contrasting strongly with respect to the ability to withstand drought stress. A total of 1813 miRNAs was identified, grouped into 106 families. Some 104 of these miRNAs were predicted to match 212 novel miRNA precursors. In the drought tolerant cultivar (SM), 105 (33 known and 72 novel) miRNAs were altered in abundance by the imposition of drought stress, while the equivalent number in the more sensitive cultivar (SW) was 51 (20 and 31). An in silico analysis predicted that these miRNAs target at least 1959 genes in SM and 1111 in SW, suggesting their broad contribution to the drought stress response. Among the target genes were several known stress-related genes, encoding, for example, superoxide dismutase, various MYB transcription factors, various ABA signaling proteins and various MADS-box transcription factors. In many cases, the more susceptible cultivar SW behaved in a contrasting manner. The suggestion is that miRNAs represent an important aspect of the drought stress response, post-transcriptionally regulating a range of stress-related genes. Copyright © 2017 Elsevier GmbH. All rights reserved.
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Zhang, Jiyu; Duan, Zhen; Zhang, Daiyu; Zhang, Jianquan; Di, Hongyan; Wu, Fan; Wang, Yanrong
2016-03-25
Drought and high salinity are two major abiotic factors that restrict alfalfa productivity. A dehydrin protein, CsLEA, from the desert grass Cleistogenes songorica was transformed into alfalfa (Medicago sativa L.) via Agrobacterium-mediated transformation using the bar gene as a selectable marker, and the drought and salt stress tolerances of the transgenic plants were assessed. Thirty-nine of 119 transformants were positive, as screened by Basta, and further molecularly authenticated using PCR and RT-PCR. Phenotype observations revealed that the transgenic plants grew better than the wild-type (WT) plants after 15d of drought stress and 10d of salt stress: the leaves of WT alfalfa turned yellow, whereas the transgenic alfalfa leaves only wilted; after rewatering, the transgenic plants returned to a normal state, though the WT plants could not be restored. Evaluation of physiologic and biochemical indices during drought and salt stresses showed a relatively lower Na(+) content in the leaves of the transgenic plants, which would reduce toxic ion effects. In addition, the transgenic plants were able to maintain a higher relative water content (RWC), higher shoot biomass, fewer photosystem changes, decreased membrane injury, and a lower level of osmotic stress injury. These results demonstrate that overexpression of the CsLEA gene can enhance the drought and salt tolerance of transgenic alfalfa; in addition, carrying the bar gene in the genome may increase herbicide resistance. Copyright © 2016 Elsevier Inc. All rights reserved.
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Armada, E; Probanza, A; Roldán, A; Azcón, R
2016-03-15
This study evaluates the responses of Lavandula dentata under drought conditions to the inoculation with single autochthonous arbuscular mycorrhizal (AM) fungus (five fungal strains) or with their mixture and the effects of these inocula with a native Bacillus thuringiensis (endophytic bacteria). These microorganisms were drought tolerant and in general, increased plant growth and nutrition. Particularly, the AM fungal mixture and B. thuringiensis maximized plant biomass and compensated drought stress as values of antioxidant activities [superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase APX)] shown. The AMF-bacteria interactions highly reduced the plant oxidative damage of lipids [malondialdehyde (MDA)] and increased the mycorrhizal development (mainly arbuscular formation representative of symbiotic functionality). These microbial interactions explain the highest potential of dually inoculated plants to tolerate drought stress. B. thuringiensis "in vitro" under osmotic stress does not reduce its PGPB (plant growth promoting bacteria) abilities as indole acetic acid (IAA) and ACC deaminase production and phosphate solubilization indicating its capacity to improve plant growth under stress conditions. Each one of the autochthonous fungal strains maintained their particular interaction with B. thuringiensis reflecting the diversity, intrinsic abilities and inherent compatibility of these microorganisms. In general, autochthonous AM fungal species and particularly their mixture with B. thuringiensis demonstrated their potential for protecting plants against drought and helping plants to thrive in semiarid ecosystems. Copyright © 2015 Elsevier GmbH. All rights reserved.
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Viger, Maud; Smith, Hazel K.; Cohen, David; Dewoody, Jennifer; Trewin, Harriet; Steenackers, Marijke; Bastien, Catherine; Taylor, Gail
2016-01-01
Summer droughts are likely to increase in frequency and intensity across Europe, yet long-lived trees may have a limited ability to tolerate drought. It is therefore critical that we improve our understanding of phenotypic plasticity to drought in natural populations for ecologically and economically important trees such as Populus nigra L. A common garden experiment was conducted using ∼500 wild P. nigra trees, collected from 11 river populations across Europe. Phenotypic variation was found across the collection, with southern genotypes from Spain and France characterized by small leaves and limited biomass production. To examine the relationship between phenotypic variation and drought tolerance, six genotypes with contrasting leaf morphologies were subjected to a water deficit experiment. ‘North eastern’ genotypes were collected at wet sites and responded to water deficit with reduced biomass growth, slow stomatal closure and reduced water use efficiency (WUE) assessed by Δ13C. In contrast, ‘southern’ genotypes originating from arid sites showed rapid stomatal closure, improved WUE and limited leaf loss. Transcriptome analyses of a genotype from Spain (Sp2, originating from an arid site) and another from northern Italy (Ita, originating from a wet site) revealed dramatic differences in gene expression response to water deficit. Transcripts controlling leaf development and stomatal patterning, including SPCH, ANT, ER, AS1, AS2, PHB, CLV1, ERL1–3 and TMM, were down-regulated in Ita but not in Sp2 in response to drought. PMID:27174702
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Zhou, Yanli; Sun, Xudong; Yang, Yunqiang; Li, Xiong; Cheng, Ying; Yang, Yongping
2016-01-01
Stipa purpurea (S. purpurea) is the dominant plant species in the alpine steppe of the Qinghai-Tibet Plateau, China. It is highly resistant to cold and drought conditions. However, the underlying mechanisms regulating the stress tolerance are unknown. In this study, a CIPK gene from S. purpurea (SpCIPK26) was isolated. The SpCIPK26 coding region consisted of 1392 bp that encoded 464 amino acids. The protein has a highly conserved catalytic structure and regulatory domain. The expression of SpCIPK26 was induced by drought and salt stress. SpCIPK26 overexpression in Arabidopsis thaliana (A. thaliana) plants provided increased tolerance to drought and salt stress in an abscisic acid (ABA)-dependent manner. Compared with wild-type A. thaliana plants, SpCIPK26-overexpressing plants had higher survival rates, water potentials, and photosynthetic efficiency (Fv/Fm), as well as lower levels of reactive oxygen species (ROS) following exposure to drought and salt stress. Gene expression analyses indicated stress-inducible genes (RD29A, RD29B, and ABF2) and a ROS-scavenger gene (CAT1) were upregulated in SpCIPK26-overexpressing plants after stress treatments. All of these marker genes are associated with ABA-responsive cis-acting elements. Additionally, the similarities in the gene expression patterns following ABA, mannitol, and NaCl treatments suggest SpCIPK26 has an important role during plant responses to drought and salt stress and in regulating ABA signaling. PMID:27338368
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Perera, Imara Y.; Hung, Chiu-Yueh; Moore, Candace D.; Stevenson-Paulik, Jill; Boss, Wendy F.
2008-01-01
The phosphoinositide pathway and inositol-1,4,5-trisphosphate (InsP3) are implicated in plant responses to stress. To determine the downstream consequences of altered InsP3-mediated signaling, we generated transgenic Arabidopsis thaliana plants expressing the mammalian type I inositol polyphosphate 5-phosphatase (InsP 5-ptase), which specifically hydrolyzes soluble inositol phosphates and terminates the signal. Rapid transient Ca2+ responses to a cold or salt stimulus were reduced by ∼30% in these transgenic plants. Drought stress studies revealed, surprisingly, that the InsP 5-ptase plants lost less water and exhibited increased drought tolerance. The onset of the drought stress was delayed in the transgenic plants, and abscisic acid (ABA) levels increased less than in the wild-type plants. Stomatal bioassays showed that transgenic guard cells were less responsive to the inhibition of opening by ABA but showed an increased sensitivity to ABA-induced closure. Transcript profiling revealed that the drought-inducible ABA-independent transcription factor DREB2A and a subset of DREB2A-regulated genes were basally upregulated in the InsP 5-ptase plants, suggesting that InsP3 is a negative regulator of these DREB2A-regulated genes. These results indicate that the drought tolerance of the InsP 5-ptase plants is mediated in part via a DREB2A-dependent pathway and that constitutive dampening of the InsP3 signal reveals unanticipated interconnections between signaling pathways. PMID:18849493
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Tree Carbohydrate Dynamics Across a Rainfall Gradient in Panama During the 2016 ENSO
NASA Astrophysics Data System (ADS)
Dickman, L. T.; Xu, C.; Behar, H.; McDowell, N.
2017-12-01
Non-structural carbohydrates (NSC) provide a measure of the carbon supply available to support respiration, growth, and defense. Support for a role of carbon starvation - or depletion of NSC stores - in drought induced tree mortality is varied without consensus for the tropics. The 2016 ENSO drought provided a unique opportunity to capture drought impacts on tropical forest carbohydrate dynamics. To quantify these impacts, we collected monthly NSC samples across a rainfall gradient in Panama for the duration of the ENSO. We observed high variability in foliar NSC among species within sites. Foliage contained very little starch, indicating that total NSC dynamics are driven by soluble sugars. Foliar NSC depletion did not progress with drought duration as predicted, but showed little variation over course of the ENSO. Foliar NSC did, however, increase with rainfall, suggesting NSC depletion may occur with longer-term drought. These results suggest that, while short-term droughts like the 2016 ENSO may not have a significant impact on carbon dynamics, we may observe greater impacts as drought progresses over longer timescales. These results will be used to evaluate whether the current implementation of carbon starvation in climate models are capturing observed trends in tropical forest carbon allocation and mortality, and to tune model parameters for improved predictive capability.
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Role of tree size in moist tropical forest carbon cycling and water deficit responses.
Meakem, Victoria; Tepley, Alan J; Gonzalez-Akre, Erika B; Herrmann, Valentine; Muller-Landau, Helene C; Wright, S Joseph; Hubbell, Stephen P; Condit, Richard; Anderson-Teixeira, Kristina J
2017-06-06
Drought disproportionately affects larger trees in tropical forests, but implications for forest composition and carbon (C) cycling in relation to dry season intensity remain poorly understood. In order to characterize how C cycling is shaped by tree size and drought adaptations and how these patterns relate to spatial and temporal variation in water deficit, we analyze data from three forest dynamics plots spanning a moisture gradient in Panama that have experienced El Niño droughts. At all sites, aboveground C cycle contributions peaked below 50-cm stem diameter, with stems ≥ 50 cm accounting for on average 59% of live aboveground biomass, 45% of woody productivity and 49% of woody mortality. The dominance of drought-avoidance strategies increased interactively with stem diameter and dry season intensity. Although size-related C cycle contributions did not vary systematically across the moisture gradient under nondrought conditions, woody mortality of larger trees was disproportionately elevated under El Niño drought stress. Thus, large (> 50 cm) stems, which strongly mediate but do not necessarily dominate C cycling, have drought adaptations that compensate for their more challenging hydraulic environment, particularly in drier climates. However, these adaptations do not fully buffer the effects of severe drought, and increased large tree mortality dominates ecosystem-level drought responses. © 2017 Smithsonian. Institute New Phytologist © 2017 New Phytologist Trust.
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Tang, Lili; Cai, Hua; Ji, Wei; Luo, Xiao; Wang, Zhenyu; Wu, Jing; Wang, Xuedong; Cui, Lin; Wang, Yang; Zhu, Yanming; Bai, Xi
2013-10-01
GsZFP1 encodes a Cys2/His2-type zinc-finger protein. In our previous study, when GsZFP1 was heterologously expressed in Arabidopsis, the transgenic Arabidopsis plants exhibited enhanced drought and cold tolerance. However, it is still unknown whether GsZFP1 is also involved in salt stress. GsZFP1 is from the wild legume Glycine soja. Therefore, the aims of this study were to further elucidate the functions of the GsZFP1 gene under salt and drought stress in the forage legume alfalfa and to investigate its biochemical and physiological functions under these stress conditions. Our data showed that overexpression of GsZFP1 in alfalfa resulted in enhanced salt tolerance. Under high salinity stress, greater relative membrane permeability and malondialdehyde (MDA) content were observed and more free proline and soluble sugars accumulated in transgenic alfalfa than in the wild-type (WT) plants; in addition, the transgenic lines accumulated less Na(+) and more K(+) in both the shoots and roots. Overexpression of GsZFP1 also enhanced the drought tolerance of alfalfa. The fold-inductions of stress-responsive marker gene expression, including MtCOR47, MtRAB18, MtP5CS, and MtRD2, were greater in transgenic alfalfa than those of WT under drought stress conditions. In conclusion, the transgenic alfalfa plants generated in this study could be used for farming in salt-affected as well as arid and semi-arid areas. Copyright © 2013 Elsevier Masson SAS. All rights reserved.
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Shibata, Yutaka; Mohamed, Ahmed; Taniyama, Koichiro; Kanatani, Kentaro; Kosugi, Makiko; Fukumura, Hiroshi
2018-05-01
Some mosses are extremely tolerant of drought stress. Their high drought tolerance relies on their ability to effectively dissipate absorbed light energy to heat under dry conditions. The energy dissipation mechanism in a drought-tolerant moss, Bryum argenteum, has been investigated using low-temperature picosecond time-resolved fluorescence spectroscopy. The results are compared between moss thalli samples harvested in Antarctica and in Japan. Both samples show almost the same quenching properties, suggesting an identical drought tolerance mechanism for the same species with two completely different habitats. A global target analysis was applied to a large set of data on the fluorescence-quenching dynamics for the 430-nm (chlorophyll-a selective) and 460-nm (chlorophyll-b and carotenoid selective) excitations in the temperature region from 5 to 77 K. This analysis strongly suggested that the quencher is formed in the major peripheral antenna of photosystem II, whose emission spectrum is significantly broadened and red-shifted in its quenched form. Two emission components at around 717 and 725 nm were assigned to photosystem I (PS I). The former component at around 717 nm is mildly quenched and probably bound to the PS I core complex, while the latter at around 725 nm is probably bound to the light-harvesting complex. The dehydration treatment caused a blue shift of the PS I emission peak via reduction of the exciton energy flow to the pigment responsible for the 725 nm band.
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Stable expression of mtlD gene imparts multiple stress tolerance in finger millet.
Hema, Ramanna; Vemanna, Ramu S; Sreeramulu, Shivakumar; Reddy, Chandrasekhara P; Senthil-Kumar, Muthappa; Udayakumar, Makarla
2014-01-01
Finger millet is susceptible to abiotic stresses, especially drought and salinity stress, in the field during seed germination and early stages of seedling development. Therefore developing stress tolerant finger millet plants combating drought, salinity and associated oxidative stress in these two growth stages is important. Cellular protection through osmotic adjustment and efficient free radical scavenging ability during abiotic stress are important components of stress tolerance mechanisms in plants. Mannitol, an osmolyte, is known to scavenge hydroxyl radicals generated during various abiotic stresses and thereby minimize stress damage in several plant species. In this study transgenic finger millet plants expressing the mannitol biosynthetic pathway gene from bacteria, mannitol-1-phosphate dehydrogenase (mtlD), were developed through Agrobacterium tumefaciens-mediated genetic transformation. mtlD gene integration in the putative transgenic plants was confirmed by Southern blot. Further, performance of transgenic finger millet under drought, salinity and oxidative stress was studied at plant level in T1 generation and in T1 and T2 generation seedlings. Results from these experiments showed that transgenic finger millet had better growth under drought and salinity stress compared to wild-type. At plant level, transgenic plants showed better osmotic adjustment and chlorophyll retention under drought stress compared to the wild-type. However, the overall increase in stress tolerance of transgenics for the three stresses, especially for oxidative stress, was only marginal compared to other mtlD gene expressing plant species reported in the literature. Moreover, the Agrobacterium-mediated genetic transformation protocol developed for finger millet in this study can be used to introduce diverse traits of agronomic importance in finger millet.
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Nelson, Donald E; Repetti, Peter P; Adams, Tom R; Creelman, Robert A; Wu, Jingrui; Warner, David C; Anstrom, Don C; Bensen, Robert J; Castiglioni, Paolo P; Donnarummo, Meghan G; Hinchey, Brendan S; Kumimoto, Roderick W; Maszle, Don R; Canales, Roger D; Krolikowski, Katherine A; Dotson, Stanton B; Gutterson, Neal; Ratcliffe, Oliver J; Heard, Jacqueline E
2007-10-16
Commercially improved crop performance under drought conditions has been challenging because of the complexity of the trait and the multitude of factors that influence yield. Here we report the results of a functional genomics approach that identified a transcription factor from the nuclear factor Y (NF-Y) family, AtNF-YB1, which acts through a previously undescribed mechanism to confer improved performance in Arabidopsis under drought conditions. An orthologous maize transcription factor, ZmNF-YB2, is shown to have an equivalent activity. Under water-limited conditions, transgenic maize plants with increased ZmNF-YB2 expression show tolerance to drought based on the responses of a number of stress-related parameters, including chlorophyll content, stomatal conductance, leaf temperature, reduced wilting, and maintenance of photosynthesis. These stress adaptations contribute to a grain yield advantage to maize under water-limited environments. The application of this technology has the potential to significantly impact maize production systems that experience drought.
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Nelson, Donald E.; Repetti, Peter P.; Adams, Tom R.; Creelman, Robert A.; Wu, Jingrui; Warner, David C.; Anstrom, Don C.; Bensen, Robert J.; Castiglioni, Paolo P.; Donnarummo, Meghan G.; Hinchey, Brendan S.; Kumimoto, Roderick W.; Maszle, Don R.; Canales, Roger D.; Krolikowski, Katherine A.; Dotson, Stanton B.; Gutterson, Neal; Ratcliffe, Oliver J.; Heard, Jacqueline E.
2007-01-01
Commercially improved crop performance under drought conditions has been challenging because of the complexity of the trait and the multitude of factors that influence yield. Here we report the results of a functional genomics approach that identified a transcription factor from the nuclear factor Y (NF-Y) family, AtNF-YB1, which acts through a previously undescribed mechanism to confer improved performance in Arabidopsis under drought conditions. An orthologous maize transcription factor, ZmNF-YB2, is shown to have an equivalent activity. Under water-limited conditions, transgenic maize plants with increased ZmNF-YB2 expression show tolerance to drought based on the responses of a number of stress-related parameters, including chlorophyll content, stomatal conductance, leaf temperature, reduced wilting, and maintenance of photosynthesis. These stress adaptations contribute to a grain yield advantage to maize under water-limited environments. The application of this technology has the potential to significantly impact maize production systems that experience drought. PMID:17923671
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Competitive ability, stress tolerance and plant interactions along stress gradients.
Qi, Man; Sun, Tao; Xue, SuFeng; Yang, Wei; Shao, DongDong; Martínez-López, Javier
2018-04-01
Exceptions to the generality of the stress-gradient hypothesis (SGH) may be reconciled by considering species-specific traits and stress tolerance strategies. Studies have tested stress tolerance and competitive ability in mediating interaction outcomes, but few have incorporated this to predict how species interactions shift between competition and facilitation along stress gradients. We used field surveys, salt tolerance and competition experiments to develop a predictive model interspecific interaction shifts across salinity stress gradients. Field survey and greenhouse tolerance tests revealed tradeoffs between stress tolerance and competitive ability. Modeling showed that along salinity gradients, (1) plant interactions shifted from competition to facilitation at high salinities within the physiological limits of salt-intolerant plants, (2) facilitation collapsed when salinity stress exceeded the physiological tolerance of salt-intolerant plants, and (3) neighbor removal experiments overestimate interspecific facilitation by including intraspecific effects. A community-level field experiment, suggested that (1) species interactions are competitive in benign and, facilitative in harsh condition, but fuzzy under medium environmental stress due to niche differences of species and weak stress amelioration, and (2) the SGH works on strong but not weak stress gradients, so SGH confusion arises when it is applied across questionable stress gradients. Our study clarifies how species interactions vary along stress gradients. Moving forward, focusing on SGH applications rather than exceptions on weak or nonexistent gradients would be most productive. © 2018 by the Ecological Society of America.
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Ectopic expression of specific GA2 oxidase mutants promotes yield and stress tolerance in rice.
Lo, Shuen-Fang; Ho, Tuan-Hua David; Liu, Yi-Lun; Jiang, Mirng-Jier; Hsieh, Kun-Ting; Chen, Ku-Ting; Yu, Lin-Chih; Lee, Miin-Huey; Chen, Chi-Yu; Huang, Tzu-Pi; Kojima, Mikiko; Sakakibara, Hitoshi; Chen, Liang-Jwu; Yu, Su-May
2017-07-01
A major challenge of modern agricultural biotechnology is the optimization of plant architecture for enhanced productivity, stress tolerance and water use efficiency (WUE). To optimize plant height and tillering that directly link to grain yield in cereals and are known to be tightly regulated by gibberellins (GAs), we attenuated the endogenous levels of GAs in rice via its degradation. GA 2-oxidase (GA2ox) is a key enzyme that inactivates endogenous GAs and their precursors. We identified three conserved domains in a unique class of C 20 GA2ox, GA2ox6, which is known to regulate the architecture and function of rice plants. We mutated nine specific amino acids in these conserved domains and observed a gradient of effects on plant height. Ectopic expression of some of these GA2ox6 mutants moderately lowered GA levels and reprogrammed transcriptional networks, leading to reduced plant height, more productive tillers, expanded root system, higher WUE and photosynthesis rate, and elevated abiotic and biotic stress tolerance in transgenic rice. Combinations of these beneficial traits conferred not only drought and disease tolerance but also increased grain yield by 10-30% in field trials. Our studies hold the promise of manipulating GA levels to substantially improve plant architecture, stress tolerance and grain yield in rice and possibly in other major crops. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.
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NASA Astrophysics Data System (ADS)
Ritson, Jonathan P.; Brazier, Richard E.; Graham, Nigel J. D.; Freeman, Chris; Templeton, Michael R.; Clark, Joanna M.
2017-06-01
Drought conditions are expected to increase in frequency and severity as the climate changes, representing a threat to carbon sequestered in peat soils. Downstream water treatment works are also at risk of regulatory compliance failures and higher treatment costs due to the increase in riverine dissolved organic carbon (DOC) often observed after droughts. More frequent droughts may also shift dominant vegetation in peatlands from Sphagnum moss to more drought-tolerant species. This paper examines the impact of drought on the production and treatability of DOC from four vegetation litters (Calluna vulgaris, Juncus effusus, Molinia caerulea and Sphagnum spp.) and a peat soil. We found that mild droughts caused a 39.6 % increase in DOC production from peat and that peat DOC that had been exposed to oxygen was harder to remove by conventional water treatment processes (coagulation/flocculation). Drought had no effect on the amount of DOC production from vegetation litters; however large variation was observed between typical peatland species (Sphagnum and Calluna) and drought-tolerant grassland species (Juncus and Molinia), with the latter producing more DOC per unit weight. This would therefore suggest the increase in riverine DOC often observed post-drought is due entirely to soil microbial processes and DOC solubility rather than litter layer effects. Long-term shifts in species diversity may, therefore, be the most important impact of drought on litter layer DOC flux, whereas pulses related to drought may be observed in peat soils and are likely to become more common in the future. These results provide evidence in support of catchment management which increases the resilience of peat soils to drought, such as ditch blocking to raise water tables.
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Zhang, Cuimei; Shi, Shangli
2018-01-01
Drought severely limits global plant distribution and agricultural production. Elucidating the physiological and molecular mechanisms governing alfalfa stress responses will contribute to the improvement of drought tolerance in leguminous crops. In this study, the physiological and proteomic responses of two alfalfa ( Medicago sativa L.) varieties contrasting in drought tolerance, Longzhong (drought-tolerant) and Gannong No. 3 (drought-sensitive), were comparatively assayed when seedlings were exposed to -1.2 MPa polyethylene glycol (PEG-6000) treatments for 15 days. The results showed that the levels of proline, malondialdehyde (MDA), hydrogen peroxide (H 2 O 2 ), hydroxyl free radical (OH • ) and superoxide anion free radical (O 2 •- ) in both varieties were significantly increased, while the root activity, the superoxide dismutase (SOD) and glutathione reductase (GR) activities, and the ratios of reduced/oxidized ascorbate (AsA/DHA) and reduced/oxidized glutathione (GSH/GSSG) were significantly decreased. The soluble protein and soluble sugar contents, the total antioxidant capability (T-AOC) and the activities of peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) first increased and then decreased with the increase in treatment days. Under osmotic stress, Longzhong exhibited lower levels of MDA, H 2 O 2 , OH • and O 2 •- but higher levels of SOD, CAT, APX, T-AOC and ratios of AsA/DHA and GSH/GSSG compared with Gannong No.3. Using isobaric tags for relative and absolute quantification (iTRAQ), 142 differentially accumulated proteins (DAPs) were identified from two alfalfa varieties, including 52 proteins (34 up-regulated and 18 down-regulated) in Longzhong, 71 proteins (28 up-regulated and 43 down-regulated) in Gannong No. 3, and 19 proteins (13 up-regulated and 6 down-regulated) shared by both varieties. Most of these DAPs were involved in stress and defense, protein metabolism, transmembrane transport, signal transduction, as well as cell wall and cytoskeleton metabolism. In conclusion, the stronger drought-tolerance of Longzhong was attributed to its higher osmotic adjustment capacity, greater ability to orchestrate its enzymatic and non-enzymatic antioxidant systems and thus avoid great oxidative damage in comparison to Gannong No. 3. Moreover, the involvement of other pathways, including carbohydrate metabolism, ROS detoxification, secondary metabolism, protein processing, ion and water transport, signal transduction, and cell wall adjustment, are important mechanisms for conferring drought tolerance in alfalfa.
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Zhang, Cuimei; Shi, Shangli
2018-01-01
Drought severely limits global plant distribution and agricultural production. Elucidating the physiological and molecular mechanisms governing alfalfa stress responses will contribute to the improvement of drought tolerance in leguminous crops. In this study, the physiological and proteomic responses of two alfalfa (Medicago sativa L.) varieties contrasting in drought tolerance, Longzhong (drought-tolerant) and Gannong No. 3 (drought-sensitive), were comparatively assayed when seedlings were exposed to -1.2 MPa polyethylene glycol (PEG-6000) treatments for 15 days. The results showed that the levels of proline, malondialdehyde (MDA), hydrogen peroxide (H2O2), hydroxyl free radical (OH•) and superoxide anion free radical (O2•-) in both varieties were significantly increased, while the root activity, the superoxide dismutase (SOD) and glutathione reductase (GR) activities, and the ratios of reduced/oxidized ascorbate (AsA/DHA) and reduced/oxidized glutathione (GSH/GSSG) were significantly decreased. The soluble protein and soluble sugar contents, the total antioxidant capability (T-AOC) and the activities of peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) first increased and then decreased with the increase in treatment days. Under osmotic stress, Longzhong exhibited lower levels of MDA, H2O2, OH• and O2•- but higher levels of SOD, CAT, APX, T-AOC and ratios of AsA/DHA and GSH/GSSG compared with Gannong No.3. Using isobaric tags for relative and absolute quantification (iTRAQ), 142 differentially accumulated proteins (DAPs) were identified from two alfalfa varieties, including 52 proteins (34 up-regulated and 18 down-regulated) in Longzhong, 71 proteins (28 up-regulated and 43 down-regulated) in Gannong No. 3, and 19 proteins (13 up-regulated and 6 down-regulated) shared by both varieties. Most of these DAPs were involved in stress and defense, protein metabolism, transmembrane transport, signal transduction, as well as cell wall and cytoskeleton metabolism. In conclusion, the stronger drought-tolerance of Longzhong was attributed to its higher osmotic adjustment capacity, greater ability to orchestrate its enzymatic and non-enzymatic antioxidant systems and thus avoid great oxidative damage in comparison to Gannong No. 3. Moreover, the involvement of other pathways, including carbohydrate metabolism, ROS detoxification, secondary metabolism, protein processing, ion and water transport, signal transduction, and cell wall adjustment, are important mechanisms for conferring drought tolerance in alfalfa. PMID:29541085
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Brenes-Arguedas, T; Roddy, A B; Coley, P D; Kursar, Thomas A
2011-06-01
In tropical forests, regional differences in annual rainfall correlate with differences in plant species composition. Although water availability is clearly one factor determining species distribution, other environmental variables that covary with rainfall may contribute to distributions. One such variable is light availability in the understory, which decreases towards wetter forests due to differences in canopy density and phenology. We established common garden experiments in three sites along a rainfall gradient across the Isthmus of Panama in order to measure the differences in understory light availability, and to evaluate their influence on the performance of 24 shade-tolerant species with contrasting distributions. Within sites, the effect of understory light availability on species performance depended strongly on water availability. When water was not limiting, either naturally in the wetter site or through water supplementation in drier sites, seedling performance improved at higher light. In contrast, when water was limiting at the drier sites, seedling performance was reduced at higher light, presumably due to an increase in water stress that affected mostly wet-distribution species. Although wetter forest understories were on average darker, wet-distribution species were not more shade-tolerant than dry-distribution species. Instead, wet-distribution species had higher absolute growth rates and, when water was not limiting, were better able to take advantage of small increases in light than dry-distribution species. Our results suggest that in wet forests the ability to grow fast during temporary increases in light may be a key trait for successful recruitment. The slower growth rates of the dry-distribution species, possibly due to trade-offs associated with greater drought tolerance, may exclude these species from wetter forests.
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USDA-ARS?s Scientific Manuscript database
Hard red winter wheat parents ‘Harry’ (drought tolerant) and ‘Wesley’ (drought susceptible) was used to develop a recombinant inbred population to identify genomic regions associated with drought and adaptation. To precisely map genomic regions high-density linkage maps are a prerequisite. In this s...
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Merewitz, Emily B.; Gianfagna, Thomas; Huang, Bingru
2011-01-01
Cytokinins (CKs) may be involved in the regulation of plant adaptation to drought stress. The objectives of the study were to identify proteomic changes in leaves and roots in relation to improved drought tolerance in transgenic creeping bentgrass (Agrostis stolonifera) containing a senescence-activated promoter (SAG12) and the isopentyl transferase (ipt) transgene that increases endogenous CK content. Leaves of SAG12-ipt bentgrass exhibited less severe senescence under water stress, as demonstrated by maintaining lower electrolyte leakage and lipid peroxidation, and higher photochemical efficiency (Fv/Fm), compared with the null transformant (NT) plants. SAG12-ipt plants had higher root/shoot ratios and lower lipid peroxidation in leaves under water stress than the NT plants. The suppression of drought-induced leaf senescence and root dieback in the transgenic plants was associated with the maintenance of greater antioxidant enzyme activities (superoxide dismutase, peroxidase, and catalase). The SAG12-ipt and NT plants exhibited differential protein expression patterns under well-watered and drought conditions in both leaves and roots. Under equivalent leaf water deficit (47% relative water content), SAG12-ipt plants maintained higher abundance of proteins involved in (i) energy production within both photosynthesis and respiration [ribulose 1,5-bisphosphate carboxylase (RuBisCO) and glyceraldehyde phosphate dehydrogenase (GAPDH)]; (ii) amino acid synthesis (methionine and glutamine); (iii) protein synthesis and destination [chloroplastic elongation factor (EF-Tu) and protein disulphide isomerases (PDIs)]; and (iv) antioxidant defence system (catalase and peroxidase) than the NT plants. These results suggest that increased endogenous CKs under drought stress may directly or indirectly regulate protein abundance and enzymatic activities involved in the above-mentioned metabolic processes, thereby enhancing plant drought tolerance. PMID:21831843
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Recchia, Gustavo Henrique; Caldas, Danielle Gregorio Gomes; Beraldo, Ana Luiza Ahern; da Silva, Márcio José; Tsai, Siu Mui
2013-01-01
In Brazil, common bean (Phaseolus vulgaris L.) productivity is severely affected by drought stress due to low technology cultivation systems. Our purpose was to identify differentially expressed genes in roots of a genotype tolerant to water deficit (BAT 477) when submitted to an interruption of irrigation during its development. A SSH library was constructed taking as “driver” the genotype Carioca 80SH (susceptible to drought). After clustering and data mining, 1572 valid reads were obtained, resulting in 1120 ESTs (expressed sequence tags). We found sequences for transcription factors, carbohydrates metabolism, proline-rich proteins, aquaporins, chaperones and ubiquitins, all of them organized according to their biological processes. Our suppressive subtractive hybridization (SSH) library was validated through RT-qPCR experiment by assessing the expression patterns of 10 selected genes in both genotypes under stressed and control conditions. Finally, the expression patterns of 31 ESTs, putatively related to drought responses, were analyzed in a time-course experiment. Our results confirmed that such genes are more expressed in the tolerant genotype during stress; however, they are not exclusive, since different levels of these transcripts were also detected in the susceptible genotype. In addition, we observed a fluctuation in gene regulation over time for both the genotypes, which seem to adopt and adapt different strategies in order to develop tolerance against this stress. PMID:23538843
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Gaspar, Maria João; Velasco, Tania; Feito, Isabel; Alía, Ricardo; Majada, Juan
2013-01-01
Understanding the survival capacity of forest trees to periods of severe water stress could improve knowledge of the adaptive potential of different species under future climatic scenarios. In long lived organisms, like forest trees, the combination of induced osmotic stress treatments and field testing can elucidate the role of drought tolerance during the early stages of establishment, the most critical in the life of the species. We performed a Polyethylene glycol-osmotic induced stress experiment and evaluated two common garden experiments (xeric and mesic sites) to test for survival and growth of a wide range clonal collection of Maritime pine. This study demonstrates the importance of additive vs non additive effects for drought tolerance traits in Pinus pinaster, and shows differences in parameters determining the adaptive trajectories of populations and family and clones within populations. The results show that osmotic adjustment plays an important role in population variation, while biomass allocation and hydric content greatly influence survival at population level. Survival in the induced osmotic stress experiment presented significant correlations with survival in the xeric site, and height growth at the mesic site, at population level, indicating constraints of adaptation for those traits, while at the within population level no significant correlation existed. These results demonstrate that population differentiation and within population genetic variation for drought tolerance follow different patterns.
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Gaspar, Maria João; Velasco, Tania; Feito, Isabel; Alía, Ricardo; Majada, Juan
2013-01-01
Understanding the survival capacity of forest trees to periods of severe water stress could improve knowledge of the adaptive potential of different species under future climatic scenarios. In long lived organisms, like forest trees, the combination of induced osmotic stress treatments and field testing can elucidate the role of drought tolerance during the early stages of establishment, the most critical in the life of the species. We performed a Polyethylene glycol-osmotic induced stress experiment and evaluated two common garden experiments (xeric and mesic sites) to test for survival and growth of a wide range clonal collection of Maritime pine. This study demonstrates the importance of additive vs non additive effects for drought tolerance traits in Pinus pinaster, and shows differences in parameters determining the adaptive trajectories of populations and family and clones within populations. The results show that osmotic adjustment plays an important role in population variation, while biomass allocation and hydric content greatly influence survival at population level. Survival in the induced osmotic stress experiment presented significant correlations with survival in the xeric site, and height growth at the mesic site, at population level, indicating constraints of adaptation for those traits, while at the within population level no significant correlation existed. These results demonstrate that population differentiation and within population genetic variation for drought tolerance follow different patterns. PMID:24223885
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Peng, Yunling; Zhang, Jinpeng; Cao, Gaoyi; Xie, Yuanhong; Liu, Xihui; Lu, Minhui; Wang, Guoying
2010-07-01
Phospholipase D (PLD) plays an important role in various physiological processes in plants, including drought tolerance. Here, we report the cloning and characterization of the full-length cDNA of PLDalpha1 from foxtail millet, which is a cereal crop with high water use efficiency. The expression pattern of the SiPLDalpha1 gene in foxtail millet revealed that it is up-regulated under dehydration, ABA and NaCl treatments. Heterologous overexpression of SiPLDalpha1 in Arabidopsis can significantly enhance their sensitivity to ABA, NaCl and mannitol during post-germination growth. Under water deprivation, overexpression of SiPLDalpha1 in Arabidopsis resulted in significantly enhanced tolerance to drought stress, displaying higher biomass and RWC, lower ion leakage and higher survival percentages than the wild type. Further analysis indicated that transgenic plants showed increased transcription of the stress-related genes, RD29A, RD29B, RAB18 and RD22, and the ABA-related genes, ABI1 and NCED3 under dehydration conditions. These results demonstrate that SiPLDalpha1 is involved in plant stress signal transduction, especially in the ABA signaling pathway. Moreover, no obvious adverse effects on growth and development in the 35S::SiPLDalpha1 transgenic plants implied that SiPLDalpha1 is a good candidate gene for improving crop drought tolerance.
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Multiple filters affect tree species assembly in mid-latitude forest communities.
Kubota, Y; Kusumoto, B; Shiono, T; Ulrich, W
2018-05-01
Species assembly patterns of local communities are shaped by the balance between multiple abiotic/biotic filters and dispersal that both select individuals from species pools at the regional scale. Knowledge regarding functional assembly can provide insight into the relative importance of the deterministic and stochastic processes that shape species assembly. We evaluated the hierarchical roles of the α niche and β niches by analyzing the influence of environmental filtering relative to functional traits on geographical patterns of tree species assembly in mid-latitude forests. Using forest plot datasets, we examined the α niche traits (leaf and wood traits) and β niche properties (cold/drought tolerance) of tree species, and tested non-randomness (clustering/over-dispersion) of trait assembly based on null models that assumed two types of species pools related to biogeographical regions. For most plots, species assembly patterns fell within the range of random expectation. However, particularly for cold/drought tolerance-related β niche properties, deviation from randomness was frequently found; non-random clustering was predominant in higher latitudes with harsh climates. Our findings demonstrate that both randomness and non-randomness in trait assembly emerged as a result of the α and β niches, although we suggest the potential role of dispersal processes and/or species equalization through trait similarities in generating the prevalence of randomness. Clustering of β niche traits along latitudinal climatic gradients provides clear evidence of species sorting by filtering particular traits. Our results reveal that multiple filters through functional niches and stochastic processes jointly shape geographical patterns of species assembly across mid-latitude forests.
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Impact of interspecific competition and drought on the allocation of new assimilates in trees.
Hommel, R; Siegwolf, R; Zavadlav, S; Arend, M; Schaub, M; Galiano, L; Haeni, M; Kayler, Z E; Gessler, A
2016-09-01
In trees, the interplay between reduced carbon assimilation and the inability to transport carbohydrates to the sites of demand under drought might be one of the mechanisms leading to carbon starvation. However, we largely lack knowledge on how drought effects on new assimilate allocation differ between species with different drought sensitivities and how these effects are modified by interspecific competition. We assessed the fate of (13) C labelled assimilates in above- and belowground plant organs and in root/rhizosphere respired CO2 in saplings of drought-tolerant Norway maple (Acer platanoides) and drought-sensitive European beech (Fagus sylvatica) exposed to moderate drought, either in mono- or mixed culture. While drought reduced stomatal conductance and photosynthesis rates in both species, both maintained assimilate transport belowground. Beech even allocated more new assimilate to the roots under moderate drought compared to non-limited water supply conditions, and this pattern was even more pronounced under interspecific competition. Even though maple was a superior competitor compared to beech under non-limited soil water conditions, as indicated by the changes in above- and belowground biomass of both species in the interspecific competition treatments, we can state that beech was still able to efficiently allocate new assimilate belowground under combined drought and interspecific competition. This might be seen as a strategy to maintain root osmotic potential and to prioritise root functioning. Our results thus show that beech tolerates moderate drought stress plus competition without losing its ability to supply belowground tissues. It remains to be explored in future work if this strategy is also valid during long-term drought exposure. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.
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Heavy and frequent thinning promotes drought adaptation in Pinus sylvestris forests.
Sohn, Julia A; Hartig, Florian; Kohler, Martin; Huss, Jürgen; Bauhus, Jürgen
2016-10-01
Droughts and their negative effects on forest ecosystems are projected to increase under climate change for many regions. It has been suggested that intensive thinning could reduce drought impacts on established forests in the short-term. Most previous studies on the effect of thinning on drought impacts, however, have been confined to single forest sites. It is therefore still unclear how general and persisting the benefits of thinning are. This study assesses the potential of thinning to increase drought tolerance of the wide spread Scots pine (Pinus sylvestris) in Central Europe. We hypothesized (1) that increasing thinning intensity benefits the maintenance of radial growth of crop trees during drought (resistance) and its recovery following drought, (2) that those benefits to growth decrease with time elapsed since the last thinning and with stand age, and (3) that they may depend on drought severity as well as water limitations in pre- and post-drought periods. To test these hypotheses, we assessed the effects of thinning regime, stand age, and drought severity on radial growth of 129 Scots pine trees during and after drought events in four long-term thinning experiments in Germany. We found that thinning improved the recovery of radial growth following drought and to a lesser extent the growth resistance during a drought event. Growth recovery following drought was highest after the first thinning intervention and in recently and heavily thinned stands. With time since the last thinning, however, this effect decreased and could even become negative when compared to unthinned stands. Further, thinning helped to avoid an age-related decline in growth resistance (and recovery) following drought. The recovery following drought, but not the resistance during drought, was related to water limitations in the drought period. This is the first study that analyzed drought-related radial growth in trees of one species across several stands of different age. The interaction between thinning intensity and time since the last thinning underline the importance to distinguish between short- and long-term effects of thinning. According to our analysis, only thinning regimes, with relatively heavy and frequent thinning interventions would increase drought tolerance in pine stands. © 2016 by the Ecological Society of America.
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Rahman, Hifzur; Ramanathan, Valarmathi; Nallathambi, Jagedeeshselvam; Duraialagaraja, Sudhakar; Muthurajan, Raveendran
2016-05-11
NAC proteins (NAM (No apical meristem), ATAF (Arabidopsis transcription activation factor) and CUC (cup-shaped cotyledon)) are plant-specific transcription factors reported to be involved in regulating growth, development and stress responses. Salinity responsive transcriptome profiling in a set of contrasting finger millet genotypes through RNA-sequencing resulted in the identification of a NAC homolog (EcNAC 67) exhibiting differential salinity responsive expression pattern. Full length cDNA of EcNAC67 was isolated, characterized and validated for its role in abiotic stress tolerance through agrobacterium mediated genetic transformation in a rice cultivar ASD16. Bioinformatics analysis of putative NAC transcription factor (TF) isolated from a salinity tolerant finger millet showed its genetic relatedness to NAC67 family TFs in related cereals. Putative transgenic lines of rice over-expressing EcNAC67 were generated through Agrobacterium mediated transformation and presence/integration of transgene was confirmed through PCR and southern hybridization analysis. Transgenic rice plants harboring EcNAC67 showed enhanced tolerance against drought and salinity under greenhouse conditions. Transgenic rice plants were found to possess higher root and shoot biomass during stress and showed better revival ability upon relief from salinity stress. Upon drought stress, transgenic lines were found to maintain higher relative water content and lesser reduction in grain yield when compared to non-transgenic ASD16 plants. Drought induced spikelet sterility was found to be much lower in the transgenic lines than the non-transgenic ASD16. Results revealed the significant role of EcNAC67 in modulating responses against dehydration stress in rice. No detectable abnormalities in the phenotypic traits were observed in the transgenic plants under normal growth conditions. Results indicate that EcNAC67 can be used as a novel source for engineering tolerance against drought and salinity stress in rice and other crop plants.
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Baek, Woonhee; Lim, Sohee; Lee, Sung Chul
2016-05-01
Plants are constantly challenged by various environmental stresses, including high salinity and drought, and they have evolved defense mechanisms to counteract the deleterious effects of these stresses. The plant hormone abscisic acid (ABA) regulates plant growth and developmental processes and mediates abiotic stress responses. Here, we identified the Capsicum annuum DRought Tolerance 1 (CaDRT1) gene from pepper leaves treated with ABA. CaDRT1 was strongly expressed in pepper leaves in response to environmental stresses and after ABA treatment, suggesting that the CaDRT1 protein functions in the abiotic stress response. Knockdown expression of CaDRT1 via virus-induced gene silencing resulted in a high level of drought susceptibility, and this was characterized by increased transpirational water loss via decreased stomatal closure. CaDRT1-overexpressing (OX) Arabidopsis plants exhibited an ABA-hypersensitive phenotype during the germinative, seedling, and adult stages. Additionally, these CaDRT1-OX plants exhibited a drought-tolerant phenotype characterized by low levels of transpirational water loss, high leaf temperatures, increased stomatal closure, and enhanced expression levels of drought-responsive genes. Taken together, our results suggest that CaDRT1 is a positive regulator of the ABA-mediated drought stress response.
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Seaweed extract improve drought tolerance of soybean by regulating stress-response genes.
Shukla, Pushp S; Shotton, Katy; Norman, Erin; Neily, Will; Critchley, Alan T; Prithiviraj, Balakrishnan
2018-02-01
There is an increasing global concern about the availability of water for agricultural use. Drought stress negatively impacts plant physiology and crop productivity. Soybean ( Glycine max ) is one of the important oilseed crops, and its productivity is often reduced by drought. In this study, a commercial extract of Ascophyllum nodosum (ANE) was evaluated for its potential to alleviate drought stress in soybean. The aim of this study was to determine the effects of ANE on the response of soybean plants to drought stress by monitoring stomatal conductance, relative leaf water content, antioxidant activity and expression of stress-responsive genes. Plants treated with ANE had higher relative water content and higher stomatal conductance under drought stress. During early recovery in the post-drought phase, ANE treated plants had significantly higher stomatal conductance. The antioxidant activity was also found higher in the plants treated with ANE. In addition, ANE-treatment led to changes in the expression of stress-responsive genes: GmCYP707A1a , GmCYP707A3b , GmRD22 , GmRD20 , GmDREB1B , GmERD1 , GmNFYA3 , FIB1a , GmPIP1b , GmGST , GmBIP and GmTp55 . Taken together, these results suggest that applications of ANE improve the drought tolerance of soybean by changing physiology and gene expression.
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Drigo, Barbara; Nielsen, Uffe N; Jeffries, Thomas C; Curlevski, Nathalie J A; Singh, Brajesh K; Duursma, Remko A; Anderson, Ian C
2017-08-01
Global change models indicate that rainfall patterns are likely to shift towards more extreme events concurrent with increasing atmospheric carbon dioxide concentration ([CO 2 ]). Both changes in [CO 2 ] and rainfall regime are known to impact above- and belowground communities, but the interactive effects of these global change drivers have not been well explored, particularly belowground. In this experimental study, we examined the effects of elevated [CO 2 ] (ambient + 240 ppm; [eCO 2 ]) and changes in rainfall patterns (seasonal drought) on soil microbial communities associated with forest ecosystems. Our results show that bacterial and archaeal communities are highly resistant to seasonal drought under ambient [CO 2 ]. However, substantial taxa specific responses to seasonal drought were observed at [eCO 2 ], suggesting that [eCO 2 ] compromise the resistance of microbial communities to extreme events. Within the microbial community we were able to identify three types of taxa specific responses to drought: tolerance, resilience and sensitivity that contributed to this pattern. All taxa were tolerant to seasonal drought at [aCO 2 ], whereas resilience and sensitivity to seasonal drought were much greater in [eCO 2 ]. These results provide strong evidence that [eCO 2 ] moderates soil microbial community responses to drought in forests, with potential implications for their long-term persistence and ecosystem functioning. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.
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Seaweed extract improve drought tolerance of soybean by regulating stress-response genes
Shukla, Pushp S; Shotton, Katy; Norman, Erin; Neily, Will; Critchley, Alan T
2018-01-01
Abstract There is an increasing global concern about the availability of water for agricultural use. Drought stress negatively impacts plant physiology and crop productivity. Soybean (Glycine max) is one of the important oilseed crops, and its productivity is often reduced by drought. In this study, a commercial extract of Ascophyllum nodosum (ANE) was evaluated for its potential to alleviate drought stress in soybean. The aim of this study was to determine the effects of ANE on the response of soybean plants to drought stress by monitoring stomatal conductance, relative leaf water content, antioxidant activity and expression of stress-responsive genes. Plants treated with ANE had higher relative water content and higher stomatal conductance under drought stress. During early recovery in the post-drought phase, ANE treated plants had significantly higher stomatal conductance. The antioxidant activity was also found higher in the plants treated with ANE. In addition, ANE-treatment led to changes in the expression of stress-responsive genes: GmCYP707A1a, GmCYP707A3b, GmRD22, GmRD20, GmDREB1B, GmERD1, GmNFYA3, FIB1a, GmPIP1b, GmGST, GmBIP and GmTp55. Taken together, these results suggest that applications of ANE improve the drought tolerance of soybean by changing physiology and gene expression. PMID:29308122
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Alvarez, Sophie; Roy Choudhury, Swarup; Pandey, Sona
2014-03-07
Wheat is one of the most highly cultivated cereals in the world. Like other cultivated crops, wheat production is significantly affected by abiotic stresses such as drought. Multiple wheat varieties suitable for different geographical regions of the world have been developed that are adapted to different environmental conditions; however, the molecular basis of such adaptations remains unknown in most cases. We have compared the quantitative proteomics profile of the roots of two different wheat varieties, Nesser (drought-tolerant) and Opata (drought-sensitive), in the absence and presence of abscisic acid (ABA, as a proxy for drought). A labeling LC-based quantitative proteomics approach using iTRAQ was applied to elucidate the changes in protein abundance levels. Quantitative differences in protein levels were analyzed for the evaluation of inherent differences between the two varieties as well as the overall and variety-specific effect of ABA on the root proteome. This study reveals the most elaborate ABA-responsive root proteome identified to date in wheat. A large number of proteins exhibited inherently different expression levels between Nesser and Opata. Additionally, significantly higher numbers of proteins were ABA-responsive in Nesser roots compared with Opata roots. Furthermore, several proteins showed variety-specific regulation by ABA, suggesting their role in drought adaptation.
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Chen, Yanhui; Han, Yangyang; Zhang, Meng; Zhou, Shan; Kong, Xiangzhu; Wang, Wei
2016-01-01
Expansins are cell wall proteins that are grouped into two main families, α-expansins and β-expansins, and they are implicated in the control of cell extension via the disruption of hydrogen bonds between cellulose and matrix glucans. TaEXPA2 is an α-expansin gene identified in wheat. Based on putative cis-regulatory elements in the TaEXPA2 promoter sequence and the expression pattern induced when polyethylene glycol (PEG) is used to mimic water stress, we hypothesized that TaEXPA2 is involved in plant drought tolerance and plant development. Through transient expression of 35S::TaEXPA2-GFP in onion epidermal cells, TaEXPA2 was localized to the cell wall. Constitutive expression of TaEXPA2 in tobacco improved seed production by increasing capsule number, not seed size, without having any effect on plant growth patterns. The transgenic tobacco exhibited a significantly greater tolerance to water-deficiency stress than did wild-type (WT) plants. We found that under drought stress, the transgenic plants maintained a better water status. The accumulated content of osmotic adjustment substances, such as proline, in TaEXPA2 transgenic plants was greater than that in WT plants. Transgenic plants also displayed greater antioxidative competence as indicated by their lower malondialdehyde (MDA) content, relative electrical conductivity, and reactive oxygen species (ROS) accumulation than did WT plants. This result suggests that the transgenic plants suffer less damage from ROS under drought conditions. The activities of some antioxidant enzymes as well as expression levels of several genes encoding key antioxidant enzymes were higher in the transgenic plants than in the WT plants under drought stress. Collectively, our results suggest that ectopic expression of the wheat expansin gene TaEXPA2 improves seed production and drought tolerance in transgenic tobacco plants.
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Singh, Kamal Krishna; Ghosh, Shilpi
2013-02-01
KEY MESSAGE : The regulation of GS isoforms by WD was organ specific. Two GS isoforms i.e. OsGS1;1 and OsGS2 were differentially regulated in IR-64 (drought-sensitive) and Khitish (drought-tolerant) cultivars of rice. Water deficit (WD) has adverse effect on rice (Oryza sativa L.) and acclimation requires essential reactions of primary metabolism to continue. Rice plants utilize ammonium as major nitrogen source, which is assimilated into glutamine by the reaction of Glutamine synthetase (GS, EC 6.3.1.2). Rice plants possess one gene (OsGS2) for chloroplastic GS2 and three genes (OsGS1;1, OsGS1;2 and OsGS1;3) for cytosolic GS1. Here, we report the effect of WD on regulation of GS isoforms in drought-sensitive (cv. IR-64) and drought-tolerant (cv. Khitish) rice cultivars. Under WD, total GS activity in root and leaf decreased significantly in IR-64 seedlings in comparison to Khitish seedlings. The reduced GS activity in IR-64 leaf was mainly due to decrease in GS2 activity, which correlated with decrease in corresponding transcript and polypeptide contents. GS1 transcript and polypeptide accumulated in leaf during WD, however, GS1 activity was maintained at a constant level. Total GS activity in stem of both the varieties was insensitive to WD. Among GS1 genes, OsGS1;1 expression was differently regulated by WD in the two rice varieties. Its transcript accumulated more abundantly in IR-64 leaf than in Khitish leaf. Following WD, OsGS1;1 mRNA level in stem and root tissues declined in IR-64 and enhanced in Khitish. A steady OsGS1;2 expression patterns were noted in leaf, stem and root of both the cultivars. Results suggest that OsGS2 and OsGS1;1 expression may contribute to drought tolerance of Khitish cultivar under WD conditions.
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Chen, Yanhui; Han, Yangyang; Zhang, Meng; Zhou, Shan; Kong, Xiangzhu; Wang, Wei
2016-01-01
Expansins are cell wall proteins that are grouped into two main families, α-expansins and β-expansins, and they are implicated in the control of cell extension via the disruption of hydrogen bonds between cellulose and matrix glucans. TaEXPA2 is an α-expansin gene identified in wheat. Based on putative cis-regulatory elements in the TaEXPA2 promoter sequence and the expression pattern induced when polyethylene glycol (PEG) is used to mimic water stress, we hypothesized that TaEXPA2 is involved in plant drought tolerance and plant development. Through transient expression of 35S::TaEXPA2-GFP in onion epidermal cells, TaEXPA2 was localized to the cell wall. Constitutive expression of TaEXPA2 in tobacco improved seed production by increasing capsule number, not seed size, without having any effect on plant growth patterns. The transgenic tobacco exhibited a significantly greater tolerance to water-deficiency stress than did wild-type (WT) plants. We found that under drought stress, the transgenic plants maintained a better water status. The accumulated content of osmotic adjustment substances, such as proline, in TaEXPA2 transgenic plants was greater than that in WT plants. Transgenic plants also displayed greater antioxidative competence as indicated by their lower malondialdehyde (MDA) content, relative electrical conductivity, and reactive oxygen species (ROS) accumulation than did WT plants. This result suggests that the transgenic plants suffer less damage from ROS under drought conditions. The activities of some antioxidant enzymes as well as expression levels of several genes encoding key antioxidant enzymes were higher in the transgenic plants than in the WT plants under drought stress. Collectively, our results suggest that ectopic expression of the wheat expansin gene TaEXPA2 improves seed production and drought tolerance in transgenic tobacco plants. PMID:27073898
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Comprehensive analysis and discovery of drought-related NAC transcription factors in common bean.
Wu, Jing; Wang, Lanfen; Wang, Shumin
2016-09-07
Common bean (Phaseolus vulgaris L.) is an important warm-season food legume. Drought is the most important environmental stress factor affecting large areas of common bean via plant death or reduced global production. The NAM, ATAF1/2 and CUC2 (NAC) domain protein family are classic transcription factors (TFs) involved in a variety of abiotic stresses, particularly drought stress. However, the NAC TFs in common bean have not been characterized. In the present study, 86 putative NAC TF proteins were identified from the common bean genome database and located on 11 common bean chromosomes. The proteins were phylogenetically clustered into 8 distinct subfamilies. The gene structure and motif composition of common bean NACs were similar in each subfamily. These results suggest that NACs in the same subfamily may possess conserved functions. The expression patterns of common bean NAC genes were also characterized. The majority of NACs exhibited specific temporal and spatial expression patterns. We identified 22 drought-related NAC TFs based on transcriptome data for drought-tolerant and drought-sensitive genotypes. Quantitative real-time PCR (qRT-PCR) was performed to confirm the expression patterns of the 20 drought-related NAC genes. Based on the common bean genome sequence, we analyzed the structural characteristics, genome distribution, and expression profiles of NAC gene family members and analyzed drought-responsive NAC genes. Our results provide useful information for the functional characterization of common bean NAC genes and rich resources and opportunities for understanding common bean drought stress tolerance mechanisms.
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Towards an integrated soil moisture drought monitor for East Africa
USDA-ARS?s Scientific Manuscript database
Drought in East Africa is a recurring phenomenon with significant humanitarian impacts. Given the steep climatic gradients, topographic contrasts, general data scarcity, and, in places, political instability that characterize the region, there is a need for spatially distributed, remotely derived mo...
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USDA-ARS?s Scientific Manuscript database
Drought is one of the major abiotic stresses limiting lentil productivity in rainfed production systems. Specific rooting patterns can be associated with drought avoidance mechanisms that can be used in lentil breeding. In all, 252 co-dominant and dominant markers were used for genetic linkage map c...
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Liu, Shanshan; Li, Hao; Lv, Xiangzhang; Ahammed, Golam Jalal; Xia, Xiaojian; Zhou, Jie; Shi, Kai; Asami, Tadao; Yu, Jingquan; Zhou, Yanhong
2016-01-01
Balancing stomata-dependent CO2 assimilation and transpiration is a key challenge for increasing crop productivity and water use efficiency under drought stress for sustainable crop production worldwide. Here, we show that cucumber and luffa plants with luffa as rootstock have intrinsically increased water use efficiency, decreased transpiration rate and less affected CO2 assimilation capacity following drought stress over those with cucumber as rootstock. Drought accelerated abscisic acid (ABA) accumulation in roots, xylem sap and leaves, and induced the transcript of ABA signaling genes, leading to a decreased stomatal aperture and transpiration in the plants grafted onto luffa roots as compared to plants grafted onto cucumber roots. Furthermore, stomatal movement in the plants grafted onto luffa roots had an increased sensitivity to ABA. Inhibition of ABA biosynthesis in luffa roots decreased the drought tolerance in cucumber and luffa plants. Our study demonstrates that the roots of luffa have developed an enhanced ability to sense the changes in root-zone moisture and could eventually deliver modest level of ABA from roots to shoots that enhances water use efficiency under drought stress. Such a mechanism could be greatly exploited to benefit the agricultural production especially in arid and semi-arid areas. PMID:26832070
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On the use of through-fall exclusion experiments to filter model hypotheses.
NASA Astrophysics Data System (ADS)
Fisher, R.
2015-12-01
One key threat to the continued existence of large tropical forest carbon reservoirs is the increasing severity of drought across Amazonian forests, observed both in climate model predictions, in recent extreme drought events and in the more chronic lengthening of the dry season of South Eastern Amazonia. Model comprehension of these systems is in it's infancy, particularly with regard to the sensitivities of model output to the representation of hydraulic strategies in tropical forest systems. Here we use data from the ongoing 14 year old Caxiuana through-fall exclusion experiment, in Eastern Brazil, to filter a set of representations of the costs and benefits of alternative hydraulic strategies. In representations where there is a high resource cost to hydraulic resilience, the trait filtering CLM4.5(ED) model selects vegetation types that are sensitive to drought. Conversely, where drought tolerance is inexpensive, a more robust ecosystem emerges from the vegetation dynamic prediction. Thus, there is an impact of trait trade-off relationships on rainforest drought tolerance. It is possible to constrain the more realistic scenarios using outputs from the drought experiments. Better prediction would likely result from a more comprehensive understanding of the costs and benefits of alternative plant strategies.
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El Rabey, Haddad A; Al-Malki, Abdulrahman L; Abulnaja, Khalid O; Rohde, Wolfgang
2015-01-01
This study was carried out to study the proteome of date palm under salinity and drought stress conditions to possibly identify proteins involved in stress tolerance. For this purpose, three-month-old seedlings of date palm cultivar "Sagie" were subjected to drought (27.5 g/L polyethylene glycol 6000) and salinity stress conditions (16 g/L NaCl) for one month. DIGE analysis of protein extracts identified 47 differentially expressed proteins in leaves of salt- and drought-treated palm seedlings. Mass spectrometric analysis identified 12 proteins; three out of them were significantly changed under both salt and drought stress, while the other nine were significantly changed only in salt-stressed plants. The levels of ATP synthase alpha and beta subunits, an unknown protein and some of RubisCO fragments were significantly changed under both salt and drought stress conditions. Changes in abundance of superoxide dismutase, chlorophyll A-B binding protein, light-harvesting complex1 protein Lhca1, RubisCO activase, phosphoglycerate kinase, chloroplast light-harvesting chlorophyll a/b-binding protein, phosphoribulokinase, transketolase, RubisCO, and some of RubisCO fragments were significant only for salt stress.
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Per, Tasir S; Khan, Nafees A; Reddy, Palakolanu Sudhakar; Masood, Asim; Hasanuzzaman, Mirza; Khan, M Iqbal R; Anjum, Naser A
2017-06-01
Major abiotic stress factors such as salt and drought adversely affect important physiological processes and biochemical mechanisms and cause severe loss in crop productivity worldwide. Plants develop various strategies to stand healthy against these stress factors. The accumulation of proline (Pro) is one of the striking metabolic responses of plants to salt and drought stress. Pro biosynthesis and signalling contribute to the redox balance of cell under normal and stressful conditions. However, literature is meager on the sustainable strategies potentially fit for modulating Pro biosynthesis and production in stressed plants. Considering the recent literature, this paper in its first part overviews Pro biosynthesis and transport in plants and also briefly highlights the significance of Pro in plant responses to salt and drought stress. Secondly, this paper discusses mechanisms underlying the regulation of Pro metabolism in salt and drought-exposed plant via phytohormones, mineral nutrients and transgenic approaches. The outcome of the studies may give new opportunities in modulating Pro metabolism for improving plant tolerance to salt and drought stress and benefit sustainable agriculture. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
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Yan, Huiru; Jia, Haihong; Chen, Xiaobo; Hao, Lili; An, Hailong; Guo, Xingqi
2014-12-01
Drought and high salinity are two major environmental factors that significantly limit the productivity of agricultural crops worldwide. WRKY transcription factors play essential roles in the adaptation of plants to abiotic stresses. However, WRKY genes involved in drought and salt tolerance in cotton (Gossypium hirsutum) are largely unknown. Here, a group IId WRKY gene, GhWRKY17, was isolated and characterized. GhWRKY17 was found to be induced after exposure to drought, salt, H2O2 and ABA. The constitutive expression of GhWRKY17 in Nicotiana benthamiana remarkably reduced plant tolerance to drought and salt stress, as determined through physiological analyses of the germination rate, root growth, survival rate, leaf water loss and Chl content. GhWRKY17 transgenic plants were observed to be more sensitive to ABA-mediated seed germination and root growth. However, overexpressing GhWRKY17 in N. benthamiana impaired ABA-induced stomatal closure. Furthermore, we found that GhWRKY17 modulated the increased sensitivity of plants to drought by reducing the level of ABA, and transcript levels of ABA-inducible genes, including AREB, DREB, NCED, ERD and LEA, were clearly repressed under drought and salt stress conditions. Consistent with the accumulation of reactive oxygen species (ROS), reduced proline contents and enzyme activities, elevated electrolyte leakage and malondialdehyde, and lower expression of ROS-scavenging genes, including APX, CAT and SOD, the GhWRKY17 transgenic plants exhibited reduced tolerance to oxidative stress compared with wild-type plants. These results therefore indicate that GhWRKY17 responds to drought and salt stress through ABA signaling and the regulation of cellular ROS production in plants. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.
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Costa E Silva, F; Shvaleva, A; Broetto, F; Ortuño, M F; Rodrigues, M L; Almeida, M H; Chaves, M M; Pereira, J S
2009-01-01
We tested the hypothesis that Eucalyptus globulus Labill. genotypes that are more resistant to dry environments might also exhibit higher cold tolerances than drought-sensitive plants. The effect of low temperatures was evaluated in acclimated and unacclimated ramets of a drought-resistant clone (CN5) and a drought-sensitive clone (ST51) of E. globulus. We studied the plants' response via leaf gas exchanges, leaf water and osmotic potentials, concentrations of soluble sugars, several antioxidant enzymes and leaf electrolyte leakage. Progressively lowering air temperatures (from 24/16 to 10/-2 degrees C, day/night) led to acclimation of both clones. Acclimated ramets exhibited higher photosynthetic rates, stomatal conductances and lower membrane relative injuries when compared to unacclimated ramets. Moreover, low temperatures led to significant increases of soluble sugars and antioxidant enzymes activity (glutathione reductase, ascorbate peroxidase and superoxide dismutases) of both clones in comparison to plants grown at control temperature (24/16 degrees C). On the other hand, none of the clones, either acclimated or not, exhibited signs of photoinhibition under low temperatures and moderate light. The main differences in the responses to low temperatures between the two clones resulted mainly from differences in carbon metabolism, including a higher accumulation of soluble sugars in the drought-resistant clone CN5 as well as a higher capacity for osmotic regulation, as compared to the drought-sensitive clone ST51. Although membrane injury data suggested that both clones had the same inherent freezing tolerance before and after cold acclimation, the results also support the hypothesis that the drought-resistant clone had a greater cold tolerance at intermediate levels of acclimation than the drought-sensitive clone. A higher capacity to acclimate in a short period can allow a clone to maintain an undamaged leaf surface area along sudden frost events, increasing growth capacity. Moreover, it can enhance survival chances in frost-prone sites expanding the plantation range with more adaptive clones.
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Zhang, Zhiqiang; Wang, Yafang; Chang, Leqin; Zhang, Tong; An, Jie; Liu, Yushi; Cao, Yuman; Zhao, Xia; Sha, Xuyang; Hu, Tianming; Yang, Peizhi
2016-02-01
The zeaxanthin epoxidase gene ( MsZEP ) was cloned and characterized from alfalfa and validated for its function of tolerance toward drought and salt stresses by heterologous expression in Nicotiana tabacum. Zeaxanthin epoxidase (ZEP) plays important roles in plant response to various environment stresses due to its functions in ABA biosynthetic and the xanthophyll cycle. To understand the expression characteristics and the biological functions of ZEP in alfalfa (Medicago sativa), a novel gene, designated as MsZEP (KM044311), was cloned, characterized and overexpressed in Nicotiana tabacum. The open reading frame of MsZEP contains 1992 bp nucleotides and encodes a 663-amino acid polypeptide. Amino acid sequence alignment indicated that deduced MsZEP protein was highly homologous to other plant ZEP sequences. Phylogenetic analysis showed that MsZEP was grouped into a branch with other legume plants. Real-time quantitative PCR revealed that MsZEP gene expression was clearly tissue-specific, and the expression levels were higher in green tissues (leaves and stems) than in roots. MsZEP expression decreased in shoots under drought, cold, heat and ABA treatment, while the expression levels in roots showed different trends. Besides, the results showed that nodules could up-regulate the MsZEP expression under non-stressful conditions and in the earlier stage of different abiotic stress. Heterologous expression of the MsZEP gene in N. tabacum could confer tolerance to drought and salt stress by affecting various physiological pathways, ABA levels and stress-responsive genes expression. Taken together, these results suggested that the MsZEP gene may be involved in alfalfa responses to different abiotic stresses and nodules, and could enhance drought and salt tolerance of transgenic tobacco by heterologous expression.
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Phenotypic and metabolic responses to drought and salinity of four contrasting lentil accessions
Muscolo, A.; Junker, A.; Klukas, C.; Weigelt-Fischer, K.; Riewe, D.; Altmann, T.
2015-01-01
Drought and salinity are among the major abiotic stresses which, often inter-relatedly, adversely affect plant growth and productivity. Plant stress responses depend on the type of stress, on its intensity, on the species, and also on the genotype. Different accessions of a species may have evolved different mechanisms to cope with stress and to complete their life cycles. This study is focused on lentil, an important Mediterranean legume with high quality protein for the human diet. The effects of salinity and drought on germination and early growth of Castelluccio di Norcia (CAST), Pantelleria (PAN), Ustica (UST), and Eston (EST) accessions were evaluated to identify metabolic and phenotypic traits related to drought and/or salinity stress tolerance. The results showed a relationship between imposed stresses and performance of the cultivars. According to germination frequencies, the accession ranking was as follows: NaCl resistant > susceptible, PAN > UST > CAST > EST; polyethylene glycol (PEG) resistant > susceptible, CAST > UST > EST > PAN. Seedling tolerance rankings were: NaCl resistant > susceptible, CAST ≈ UST > PAN ≈ EST; PEG resistant > susceptible, CAST > EST ≈ UST > PAN. Changes in the metabolite profiles, mainly quantitative rather than qualitative, were observed in the same cultivar in respect to the treatments, and among the cultivars under the same treatment. Metabolic differences in the stress tolerance of the different genotypes were related to a reduction in the levels of tricarboxylic acid (TCA) cycle intermediates. The relevant differences, between the most NaCl-tolerant genotype (PAN) and the most sensitive one (EST) were related to the decrease in the threonic acid level. Stress-specific metabolite indicators were also identified: ornithine and asparagine as markers of drought stress and alanine and homoserine as markers of salinity stress. PMID:25969553
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Stable Expression of mtlD Gene Imparts Multiple Stress Tolerance in Finger Millet
Hema, Ramanna; Vemanna, Ramu S.; Sreeramulu, Shivakumar; Reddy, Chandrasekhara P.; Senthil-Kumar, Muthappa; Udayakumar, Makarla
2014-01-01
Finger millet is susceptible to abiotic stresses, especially drought and salinity stress, in the field during seed germination and early stages of seedling development. Therefore developing stress tolerant finger millet plants combating drought, salinity and associated oxidative stress in these two growth stages is important. Cellular protection through osmotic adjustment and efficient free radical scavenging ability during abiotic stress are important components of stress tolerance mechanisms in plants. Mannitol, an osmolyte, is known to scavenge hydroxyl radicals generated during various abiotic stresses and thereby minimize stress damage in several plant species. In this study transgenic finger millet plants expressing the mannitol biosynthetic pathway gene from bacteria, mannitol-1-phosphate dehydrogenase (mtlD), were developed through Agrobacterium tumefaciens-mediated genetic transformation. mtlD gene integration in the putative transgenic plants was confirmed by Southern blot. Further, performance of transgenic finger millet under drought, salinity and oxidative stress was studied at plant level in T1 generation and in T1 and T2 generation seedlings. Results from these experiments showed that transgenic finger millet had better growth under drought and salinity stress compared to wild-type. At plant level, transgenic plants showed better osmotic adjustment and chlorophyll retention under drought stress compared to the wild-type. However, the overall increase in stress tolerance of transgenics for the three stresses, especially for oxidative stress, was only marginal compared to other mtlD gene expressing plant species reported in the literature. Moreover, the Agrobacterium-mediated genetic transformation protocol developed for finger millet in this study can be used to introduce diverse traits of agronomic importance in finger millet. PMID:24922513
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Messina, Carlos D; Podlich, Dean; Dong, Zhanshan; Samples, Mitch; Cooper, Mark
2011-01-01
The effectiveness of breeding strategies to increase drought resistance in crops could be increased further if some of the complexities in gene-to-phenotype (G → P) relations associated with epistasis, pleiotropy, and genotype-by-environment interactions could be captured in realistic G → P models, and represented in a quantitative manner useful for selection. This paper outlines a promising methodology. First, the concept of landscapes was extended from the study of fitness landscapes used in evolutionary genetics to the characterization of yield-trait-performance landscapes for agricultural environments and applications in plant breeding. Second, the E(NK) model of trait genetic architecture was extended to incorporate biophysical, physiological, and statistical components. Third, a graphical representation is proposed to visualize the yield-trait performance landscape concept for use in selection decisions. The methodology was demonstrated at a particular stage of a maize breeding programme with the objective of improving the drought tolerance of maize hybrids for the US Western Corn-Belt. The application of the framework to the genetic improvement of drought tolerance in maize supported selection of Doubled Haploid (DH) lines with improved levels of drought tolerance based on physiological genetic knowledge, prediction of test-cross yield within the target population of environments, and their predicted potential to sustain further genetic progress with additional cycles of selection. The existence of rugged yield-performance landscapes with multiple peaks and intervening valleys of lower performance, as shown in this study, supports the proposition that phenotyping strategies, and the directions emphasized in genomic selection can be improved by creating knowledge of the topology of yield-trait performance landscapes.
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Lu, Linghong; Dong, Changhe; Liu, Ruifang; Zhou, Bin; Wang, Chuang; Shou, Huixia
2018-01-01
Aquaporins play an essential role in water uptake and transport in vascular plants. The soybean genome contains a total of 22 plasma membrane intrinsic protein (PIP) genes. To identify candidate PIPs important for soybean yield and stress tolerance, we studied the transcript levels of all 22 soybean PIPs. We found that a GmPIP2 subfamily member, GmPIP2;9, was predominately expressed in roots and developing seeds. Here, we show that GmPIP2;9 localized to the plasma membrane and had high water channel activity when expressed in Xenopus oocytes. Using transgenic soybean plants expressing a native GmPIP2;9 promoter driving a GUS-reporter gene, it was found high GUS expression in the roots, in particular, in the endoderm, pericycle, and vascular tissues of the roots of transgenic plants. In addition, GmPIP2;9 was also highly expressed in developing pods. GmPIP2;9 expression significantly increased in short term of polyethylene glycol (PEG)-mediated drought stress treatment. GmPIP2;9 overexpression increased tolerance to drought stress in both solution cultures and soil plots. Drought stress in combination with GmPIP2;9 overexpression increased net CO 2 assimilation of photosynthesis, stomata conductance, and transpiration rate, suggesting that GmPIP2;9- overexpressing transgenic plants were less stressed than wild-type (WT) plants. Furthermore, field experiments showed that GmPIP2;9 -overexpressing plants had significantly more pod numbers and larger seed sizes than WT plants. In summary, the study demonstrated that GmPIP2;9 has water transport activity. Its relative high expression levels in roots and developing pods are in agreement with the phenotypes of GmPIP2;9 -overexpressing plants in drought stress tolerance and seed development.
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Lu, Linghong; Dong, Changhe; Liu, Ruifang; Zhou, Bin; Wang, Chuang; Shou, Huixia
2018-01-01
Aquaporins play an essential role in water uptake and transport in vascular plants. The soybean genome contains a total of 22 plasma membrane intrinsic protein (PIP) genes. To identify candidate PIPs important for soybean yield and stress tolerance, we studied the transcript levels of all 22 soybean PIPs. We found that a GmPIP2 subfamily member, GmPIP2;9, was predominately expressed in roots and developing seeds. Here, we show that GmPIP2;9 localized to the plasma membrane and had high water channel activity when expressed in Xenopus oocytes. Using transgenic soybean plants expressing a native GmPIP2;9 promoter driving a GUS-reporter gene, it was found high GUS expression in the roots, in particular, in the endoderm, pericycle, and vascular tissues of the roots of transgenic plants. In addition, GmPIP2;9 was also highly expressed in developing pods. GmPIP2;9 expression significantly increased in short term of polyethylene glycol (PEG)-mediated drought stress treatment. GmPIP2;9 overexpression increased tolerance to drought stress in both solution cultures and soil plots. Drought stress in combination with GmPIP2;9 overexpression increased net CO2 assimilation of photosynthesis, stomata conductance, and transpiration rate, suggesting that GmPIP2;9-overexpressing transgenic plants were less stressed than wild-type (WT) plants. Furthermore, field experiments showed that GmPIP2;9-overexpressing plants had significantly more pod numbers and larger seed sizes than WT plants. In summary, the study demonstrated that GmPIP2;9 has water transport activity. Its relative high expression levels in roots and developing pods are in agreement with the phenotypes of GmPIP2;9-overexpressing plants in drought stress tolerance and seed development. PMID:29755491
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2014-01-01
Background In plants, calcium-dependent protein kinases (CDPKs) are involved in tolerance to abiotic stresses and in plant seed development. However, the functions of only a few rice CDPKs have been clarified. At present, it is unclear whether CDPKs also play a role in regulating spikelet fertility. Results We cloned and characterized the rice CDPK gene, OsCPK9. OsCPK9 transcription was induced by abscisic acid (ABA), PEG6000, and NaCl treatments. The results of OsCPK9 overexpression (OsCPK9-OX) and OsCPK9 RNA interference (OsCPK9-RNAi) analyses revealed that OsCPK9 plays a positive role in drought stress tolerance and spikelet fertility. Physiological analyses revealed that OsCPK9 improves drought stress tolerance by enhancing stomatal closure and by improving the osmotic adjustment ability of the plant. It also improves pollen viability, thereby increasing spikelet fertility. In OsCPK9-OX plants, shoot and root elongation showed enhanced sensitivity to ABA, compared with that of wild-type. Overexpression and RNA interference of OsCPK9 affected the transcript levels of ABA- and stress-responsive genes. Conclusions Our results demonstrated that OsCPK9 is a positive regulator of abiotic stress tolerance, spikelet fertility, and ABA sensitivity. PMID:24884869
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Bresson, Justine; Vasseur, François; Dauzat, Myriam; Labadie, Marc; Varoquaux, Fabrice; Touraine, Bruno; Vile, Denis
2014-01-01
Mutualistic bacteria can alter plant phenotypes and confer new abilities to plants. Some plant growth-promoting rhizobacteria (PGPR) are known to improve both plant growth and tolerance to multiple stresses, including drought, but reports on their effects on plant survival under severe water deficits are scarce. We investigated the effect of Phyllobacterium brassicacearum STM196 strain, a PGPR isolated from the rhizosphere of oilseed rape, on survival, growth and physiological responses of Arabidopsis thaliana to severe water deficits combining destructive and non-destructive high-throughput phenotyping. Soil inoculation with STM196 greatly increased the survival rate of A. thaliana under several scenarios of severe water deficit. Photosystem II efficiency, assessed at the whole-plant level by high-throughput fluorescence imaging (F v/F m), was related to the probability of survival and revealed that STM196 delayed plant mortality. Inoculated surviving plants tolerated more damages to the photosynthetic tissues through a delayed dehydration and a better tolerance to low water status. Importantly, STM196 allowed a better recovery of plant growth after rewatering and stressed plants reached a similar biomass at flowering than non-stressed plants. Our results highlight the importance of plant-bacteria interactions in plant responses to severe drought and provide a new avenue of investigations to improve drought tolerance in agriculture. PMID:25226036
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Challenges in breeding for yield increase for drought.
Sinclair, Thomas R
2011-06-01
Crop genetic improvement for environmental stress at the molecular and physiological level is very complex and challenging. Unlike the example of the current major commercial transgenic crops for which biotic stress tolerance is based on chemicals alien to plants, the complex, redundant and homeostatic molecular and physiological systems existing in plants must be altered for drought tolerance improvement. Sophisticated tools must be developed to monitor phenotype expression at the crop level to characterize variation among genotypes across a range of environments. Once stress-tolerant cultivars are developed, regional probability distributions describing yield response across years will be necessary. This information can then aid in identifying environmental conditions for positive and negative responses to genetic modification to guide farmer selection of stress-tolerant cultivars. Copyright © 2011 Elsevier Ltd. All rights reserved.