Screening of a new cadmium hyperaccumulator, Galinsoga parviflora, from winter farmland weeds using the artificially high soil cadmium concentration method.

PubMed

Lin, Lijin; Jin, Qian; Liu, Yingjie; Ning, Bo; Liao, Ming'an; Luo, Li

2014-11-01

A new method, the artificially high soil cadmium (Cd) concentration method, was used to screen for Cd hyperaccumulators among winter farmland weeds. Galinsoga parviflora was the most promising remedial plant among 5 Cd accumulators or hyperaccumulators. In Cd concentration gradient experiments, as soil Cd concentration increased, root and shoot biomass decreased, and their Cd contents increased. In additional concentration gradient experiments, superoxide dismutase and peroxidase activities increased with soil Cd concentrations up to 75 mg kg(-1) , while expression of their isoenzymes strengthened. Catalase (CAT) activity declined and CAT isoenzyme expression weakened at soil Cd concentrations less than 50 mg kg(-1) . The maxima of Cd contents in shoots and roots were 137.63 mg kg(-1) and 105.70 mg kg(-1) , respectively, at 100 mg kg(-1) Cd in soil. The root and shoot bioconcentration factors exceeded 1.0, as did the translocation factor. In a field experiment, total extraction of Cd by shoots was 1.35 mg m(-2) to 1.43 mg m(-2) at soil Cd levels of 2.04 mg kg(-1) to 2.89 mg kg(-1) . Therefore, the artificially high soil Cd concentration method was effective for screening Cd hyperaccumulators. Galinsoga parviflora is a Cd hyperaccumulator that could be used to efficiently remediate Cd-contaminated farmland soil. © 2014 SETAC.

Fine root respiration in the mangrove Rhizophora mangle over variation in forest stature and nutrient availability.

PubMed

Lovelock, Catherine E; Ruess, Roger W; Feller, Ilka C

2006-12-01

Root respiration uses a significant proportion of photosynthetically fixed carbon (C) and is a globally important source of C liberated from soils. Mangroves, which are an important and productive forest resource in many tropical and subtropical countries, sustain a high ratio of root to shoot biomass which may indicate that root respiration is a particularly important component in mangrove forest carbon budgets. Mangroves are often exposed to nutrient pollution from coastal waters. Here we assessed the magnitude of fine root respiration in mangrove forests in Belize and investigated how root respiration is influenced by nutrient additions. Respiration rates of excised fine roots of the mangrove, Rhizophora mangle L., were low (4.01 +/- 0.16 nmol CO(2) g(-1) s(-1)) compared to those measured in temperate tree species at similar temperatures. In an experiment where trees where fertilized with nitrogen (N) or phosphorus (P) in low productivity dwarf forests (1-2 m height) and more productive, taller (4- 7 m height) seaward fringing forests, respiration of fine roots did not vary consistently with fertilization treatments or with forest stature. Fine roots of taller fringe trees had higher concentrations of both N and P compared to dwarf trees. Fertilization with P enhanced fine root P concentrations in both dwarf and fringe trees, but reduced root N concentrations compared to controls. Fertilization with N had no effect on root N or P concentrations. Unlike photosynthetic C gain and growth, which is strongly limited by P availability in dwarf forests at this site, fine root respiration (expressed on a mass basis) was variable, but showed no significant enhancements with nutrient additions. Variation in fine root production and standing biomass are, therefore, likely to be more important factors determining C efflux from mangrove sediments than variations in fine root respiration per unit mass.

Seasonal Changes Affect Root Prunasin Concentration in Prunus serotina and Override Species Interactions between P. serotina and Quercus petraea.

PubMed

Robakowski, Piotr; Bielinis, Ernest; Stachowiak, Jerzy; Mejza, Iwona; Bułaj, Bartosz

2016-03-01

The allocation of resources to chemical defense can decrease plant growth and photosynthesis. Prunasin is a cyanogenic glycoside known for its role in defense against herbivores and other plants. In the present study, fluctuations of prunasin concentrations in roots of Prunus serotina seedlings were hypothesized to be: (1) dependent on light, air temperature, and humidity; (2) affected by competition between Prunus serotina and Quercus petraea seedlings, with mulching with Prunus serotina leaves; (3) connected with optimal allocation of resources. For the first time, we determined prunasin concentration in roots on several occasions during the vegetative season. The results indicate that seasonal changes have more pronounced effects on prunasin concentration than light regime and interspecific competition. Prunus serotina invested more nitrogen in the synthesis of prunasin under highly restricted light conditions than in higher light environments. In full sun, prunasin in roots of Prunus serotina growing in a monoculture was correlated with growth and photosynthesis, whereas these relationships were not found when interspecific competition with mulching was a factor. The study demonstrates that prunasin concentration in Prunus serotina roots is the result of species-specific adaptation, light and temperature conditions, ontogenetic shift, and, to a lesser extent, interspecific plant-plant interactions.

Proteomic analysis of Populus × euramericana (clone I-214) roots to identify key factors involved in zinc stress response.

PubMed

Romeo, Stefania; Trupiano, Dalila; Ariani, Andrea; Renzone, Giovanni; Scippa, Gabriella S; Scaloni, Andrea; Sebastiani, Luca

2014-07-15

Contamination of soil and water by heavy metals has become a widespread problem; environmental pollution by high zinc (Zn) concentration occurs frequently. Although poplar (Populus spp.) has been identified as suitable for phytoremediation approaches, its response to high Zn concentrations are still not clearly understood. For this reason, we investigated the effects of Zn in Populus×euramericana clone I-214 roots by proteomic analysis. Comparative experiments were conducted on rooted woody cuttings grown in nutrient solutions containing 1mM (treatment) or 1μM (control) Zn concentrations. A gel-based proteomic approach coupled with morphological and chemical analysis was used to identify differentially represented proteins in treated roots and to investigate the effect of Zn treatment on the poplar root system. Data shows that Zn was accumulated preferentially in roots, that the antioxidant system, the carbohydrate/energy and amino acid metabolisms were the main pathways modulated by Zn excess, and that mitochondria and vacuoles were the cellular organelles predominately affected by Zn stress. A coordination between cell death and proliferation/growth seems to occur under this condition to counteract the Zn-induced damage. Copyright © 2014 Elsevier GmbH. All rights reserved.

Joint toxicity of methamidophos and cadmium acting on Abelmoschus manihot.

PubMed

Wang, Xiao-Fei; Zhou, Qi-Xing

2005-01-01

Joint toxicity of methamidophos and cadmium (Cd) on the ornamental Abelmoschus manihot was firstly examined and compared with single-factor effects of the two pollutants using ecotoxicological indexes including the inhibitory rate of seed germination, root elongation and inhibitory concentration 50% (IC50). The results indicated that methamidophos and Cd had unobvious( p > 0.05) effects on seed germination of the ornamental. There were significant( p < 0.05) inhibitory effects of Cd on root elongation of the tested plant. When the concentration of added Cd was low( < 20 mg/L), significant antagonistic effects on root elongation were observed. And synergic effects were observed when Cd was added in high dose( > 20 mg/L). However, the analysis of joint effects indicated that there were antagonistic effects between Cd and methamidophos under all the treatments. At the high concentration of Cd, joint toxicity of methamidophos and Cd was more dependent on concentration of Cd.

Perfluoroalkyl acid distribution in various plant compartments ...

EPA Pesticide Factsheets

Crop uptake of perfluoroalkyl acids (PFAAs) from biosolids-amended soil has been identified as a potential pathway for PFAA entry into the terrestrial food chain. This study compared the uptake of PFAAs in greenhouse-grown radish (Raphanus sativus), celery (Apium graveolens var.dulce), tomato (Lycopersicon lycopersicum), and sugar snap pea (Pisum sativum var. macrocarpon) from an industrially impacted biosolids-amended soil, a municipal biosolids­ amended soil, and a control soil. Individual concentrations of PFAAs, on a dry weight basis, in mature, edible portions of crops grown in soil amended with PFAA industrially impacted biosolids were highest for perfluorooctanoate (PFOA; 67 ng/g) in radish root, perfluorobutanoate (PFBA;232 ng/g) in celery shoot, and PFBA (150 ng/g) in pea fruit. Comparatively, PFAA concentrations in edible compartments of crops grown in the municipal biosolids-amended soil and in the control soil were less than 25 ng/g. Bioaccumulation factors (BAFs) were calculated for the root, shoot, and fruit compartments (as applicable) of all crops grown in the industrially impacted soil. BAFs were highest for PFBA in the shoots of all crops, as well as in the fruit compartment of pea. Root­ soil concentration factors (RCFs) for tomato and pea were independent of PFAA chain length, while radish and celery RCFs showed a slight decrease with increasing chain length. Shoot-soil concentration factors (SCFs) for all crops showed a decrease with incre

Effects of pulpectomy on the amount of root resorption during orthodontic tooth movement.

PubMed

Kaku, Masato; Sumi, Hiromi; Shikata, Hanaka; Kojima, Shunichi; Motokawa, Masahide; Fujita, Tadashi; Tanimoto, Kotaro; Tanne, Kazuo

2014-03-01

Previous studies have revealed that orthodontic force affects dental pulp via the rupture of blood vessels and vacuolization of pulp tissues. We hypothesized that pulp tissues express inflammatory cytokines and regulators of odontoclast differentiation after excess orthodontic force. The purpose of this study was to investigate the effects of tensile force in human pulp cells and to measure inflammatory root resorption during tooth movement in pulpless rat teeth. After cyclic tensile force application in human pulp cells, gene expression and protein concentration of macrophage colony-stimulating factor, receptor activator of nuclear factor kappa-B ligand, interleukin-1 beta, and tumor necrosis factor alpha were determined by real-time polymerase chain reaction and enzyme-linked immunoassay. Moreover, the role of the stretch-activated channel was evaluated by gadolinium (Gd(3+)) treatment. The upper right first molars of 7-week Wistar rats were subjected to pulpectomy and root canal filling followed by mesial movement for 6 months. The expression of cytokine messenger RNAs and proteins in the experimental group peaked with loading at 10-kPa tensile force after 48 hours (P < .01). Gd(3+) reduced the expression of these cytokine messenger RNAs and protein concentrations (P < .01). The amount of inflammatory root resorption was significantly larger in the control teeth than the pulpectomized teeth (P < .05). This study shows that tensile forces in the pulp cells enhance the expression of various cytokines via the S-A channel, which may lead to inflammatory root resorption during tooth movement. It also suggests that root canal treatment is effective for progressive severe inflammatory root resorption during tooth movement. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Effects of silicon on Oryza sativa L. seedling roots under simulated acid rain stress.

PubMed

Ju, Shuming; Yin, Ningning; Wang, Liping; Zhang, Cuiying; Wang, Yukun

2017-01-01

Silicon (Si) has an important function in reducing the damage of environmental stress on plants. Acid rain is a serious abiotic stress factor, and Si can alleviate the stress induced by acid rain on plants. Based on these assumptions, we investigated the effects of silicon on the growth, root phenotype, mineral element contents, hydrogen peroxide (H2O2) and antioxidative enzymes of rice (Oryza sativa L.) seedling roots under simulated acid rain (SAR) stress. The results showed that the combined or single effects of Si and/or SAR on rice roots depend on the concentration of Si and the pH of the SAR. The combined or single effects of a low or moderate concentration of Si (1.0 or 2.0 mM) and light SAR (pH 4.0) enhanced the growth of rice roots, and the combined effects were stronger than those of the single treatment. A high concentration of Si (4.0 mM) or severe SAR (pH 2.0) exerted deleterious effects. The incorporation of Si (1.0, 2.0 or 4.0 mM) into SAR with pH 3.0 or 2.0 promoted the rice root growth, decreased the H2O2 content, increased the Si concentration and the superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX) activities, maintained the balance of mineral element (K, Ca, Mg, Fe, Zn, and Cu) concentrations in the roots of rice seedlings compared with SAR alone. The alleviatory effects observed with a moderate concentration of Si (2.0 mM) were better than the effects obtained with a low or high concentration of Si (1.0 or 4.0 mM). The observed effects were due to disruptions in the absorption and utilization of mineral nutrients and impacts on the activity of antioxidant enzymes in roots, and this conclusion suggests that the degree of rice root damage caused by acid rain might be attributed to not only acid rain but also the level of Si in the soil.

Effects of silicon on Oryza sativa L. seedling roots under simulated acid rain stress

PubMed Central

Wang, Liping; Zhang, Cuiying; Wang, Yukun

2017-01-01

Silicon (Si) has an important function in reducing the damage of environmental stress on plants. Acid rain is a serious abiotic stress factor, and Si can alleviate the stress induced by acid rain on plants. Based on these assumptions, we investigated the effects of silicon on the growth, root phenotype, mineral element contents, hydrogen peroxide (H2O2) and antioxidative enzymes of rice (Oryza sativa L.) seedling roots under simulated acid rain (SAR) stress. The results showed that the combined or single effects of Si and/or SAR on rice roots depend on the concentration of Si and the pH of the SAR. The combined or single effects of a low or moderate concentration of Si (1.0 or 2.0 mM) and light SAR (pH 4.0) enhanced the growth of rice roots, and the combined effects were stronger than those of the single treatment. A high concentration of Si (4.0 mM) or severe SAR (pH 2.0) exerted deleterious effects. The incorporation of Si (1.0, 2.0 or 4.0 mM) into SAR with pH 3.0 or 2.0 promoted the rice root growth, decreased the H2O2 content, increased the Si concentration and the superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX) activities, maintained the balance of mineral element (K, Ca, Mg, Fe, Zn, and Cu) concentrations in the roots of rice seedlings compared with SAR alone. The alleviatory effects observed with a moderate concentration of Si (2.0 mM) were better than the effects obtained with a low or high concentration of Si (1.0 or 4.0 mM). The observed effects were due to disruptions in the absorption and utilization of mineral nutrients and impacts on the activity of antioxidant enzymes in roots, and this conclusion suggests that the degree of rice root damage caused by acid rain might be attributed to not only acid rain but also the level of Si in the soil. PMID:28291806

Factors affecting induction and development of in vitro rooting in apple rootstocks.

PubMed

Sharma, T; Modgil, M; Thakur, M

2007-09-01

Shoots of apple rootstocks raised in vitro were transferred to various rooting media to study the effect of different factors on root initiation and development. Various concentrations of indole-3-butyric acid (IBA) initiated rooting but maximum rooting percentage was found with 2.0 and 2.5 mg l(-1) of IBA in M7 and with 1.0 mg l(-1) of IBA in MM106. The drawback was that the roots were thick, short and with profuse callus. The presence of activated charcoal (AC) in the rooting medium improved the rooting quality but reduced the rooting percentage in both the rootstocks. In high auxin dip of 70, 80 and 90 mg l(-1) IBA for 2, 2 and 1 hr showed 75-85 per cent rooting in M7, but lacked reproducibility of the results. Whereas in MM106, 66 - 70 % rooting was achieved with 70 mg l(-1) of IBA dip for 3 h. Root induction in shoots in IBA containing liquid medium (LM) in dark for few days and root elongation in IBA--free medium in light proved most effective. On the other hand, continuous light treatment showed reduced rooting. Reduction of MS salts and sucrose in root elongation medium showed decreased rooting. Plantlets from two--stage rooting procedure showed more rapid growth and satisfactory survival during hardening of plants and on transfer to field.

Growth-inhibition patterns and transfer-factor profiles in arsenic-stressed rice (Oryza sativa L.).

PubMed

Jung, Ha-Il; Lee, Jinwook; Chae, Mi-Jin; Kong, Myung-Suk; Lee, Chang-Hoon; Kang, Seong-Soo; Kim, Yoo-Hak

2017-11-16

Arsenic (As) accumulation in rice owing to uptake from the soil is a critical human health issue. Here, we studied the chemical properties of As-treated soils, growth inhibition patterns of As-stressed rice plants, changes in the As content of soil and soil solutions, and the relationship between As accumulation and As transfer factor from the soil to the rice organs. Rice plants were cultivated in a greenhouse under four concentrations of As: 0 (control), 25, 50, and 75 mg kg -1 . A significant positive correlation was found between available P 2 O 5 and exchangeable K and between As concentration and available P 2 O 5 or exchangeable K. The As concentration for 50% shoot growth inhibition was 50 mg kg -1 . As levels in roots and shoots were positively correlated with the growth stages of rice. The transfer factor (TF) root/soil increased with As concentration at the tillering stage but decreased at the heading stage. TF root/soil and TF shoot/soil were higher at the heading stage than at the tillering stage. As accumulation in the 25 mg kg -1 treatment was higher during the heading stage, whereas no difference was found at the tillering stage. As accumulation was related to plant biomass and soil As concentration. We found that As accumulation was greater at As concentrations that allowed for plant growth and development. Thus, species-specific threshold concentrations must be determined based on As phytotoxicity for the phytoremediation of As-contaminated soils. Hence, developing practical approaches for managing safe crop production in farmlands with an As contamination of 25 mg kg -1 or less is necessary.

Accumulation of contaminants of emerging concern in food crops-part 2: Plant distribution.

PubMed

Hyland, Katherine C; Blaine, Andrea C; Higgins, Christopher P

2015-10-01

Arid agricultural regions often turn to using treated wastewater (reclaimed water) to irrigate food crops. Concerns arise, however, when considering the potential for persistent contaminants of emerging concern to accumulate into plants intended for human consumption. The present study examined the accumulation of a suite of 9 contaminants of emerging concern into 2 representative food crops, lettuce and strawberry, following uptake via the roots and subsequent distribution to other plant tissues. Calculating accumulation metrics (concentration factors) allowed for comparison of the compartmental affinity of each chemical for each plant tissue compartment. The root concentration factor was found to exhibit a positive linear correlation with the pH-adjusted octanol-water partition coefficient (DOW ) for the target contaminants of emerging concern. Coupled with the concentration-dependent accumulation observed in the roots, this result implies that accumulation of these contaminants of emerging concern into plant roots is driven by passive partitioning. Of the contaminants of emerging concern examined, nonionizable contaminants, such as triclocarban, carbamazepine, and organophosphate flame retardants displayed the greatest potential for translocation from the roots to above-ground plant compartments. In particular, the organophosphate flame retardants displayed increasing affinity for shoots and fruits with decreasing size/octanol-water partition coefficient (KOW ). Cationic diphenhydramine and anionic sulfamethoxazole, once transported to the shoots of the strawberry plant, demonstrated the greatest potential of the contaminants examined to be then carried to the edible fruit portion. © 2015 SETAC.

Nitrate foraging by Arabidopsis roots is mediated by the transcription factor TCP20 through the systemic signaling pathway

PubMed Central

Guan, Peizhu; Wang, Rongchen; Nacry, Philippe; Breton, Ghislain; Kay, Steve A.; Pruneda-Paz, Jose L.; Davani, Ariea; Crawford, Nigel M.

2014-01-01

To compete for nutrients in diverse soil microenvironments, plants proliferate lateral roots preferentially in nutrient-rich zones. For nitrate, root foraging involves local and systemic signaling; however, little is known about the genes that function in the systemic signaling pathway. By using nitrate enhancer DNA to screen a library of Arabidopsis transcription factors in the yeast one-hybrid system, the transcription factor gene TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR1-20 (TCP20) was identified. TCP20, which belongs to an ancient, plant-specific gene family that regulates shoot, flower, and embryo development, was implicated in nitrate signaling by its ability to bind DNA in more than 100 nitrate-regulated genes. Analysis of insertion mutants of TCP20 showed that they had normal primary and lateral root growth on homogenous nitrate media but were impaired in preferential lateral root growth (root foraging) on heterogeneous media in split-root plates. Inhibition of preferential lateral root growth was still evident in the mutants even when ammonium was uniformly present in the media, indicating that the TCP20 response was to nitrate. Comparison of tcp20 mutants with those of nlp7 mutants, which are defective in local control of root growth but not in the root-foraging response, indicated that TCP20 function is independent of and distinct from NLP7 function. Further analysis showed that tcp20 mutants lack systemic control of root growth regardless of the local nitrate concentrations. These results indicate that TCP20 plays a key role in the systemic signaling pathway that directs nitrate foraging by Arabidopsis roots. PMID:25288754

Phytostabilization potential of two ecotypes of Vetiveria zizanioides in cadmium-contaminated soils: greenhouse and field experiments.

PubMed

Phusantisampan, Theerawut; Meeinkuirt, Weeradej; Saengwilai, Patompong; Pichtel, John; Chaiyarat, Rattanawat

2016-10-01

Soil contamination by cadmium (Cd) poses a serious environmental and public health concern. Phytoremediation, i.e., the use of plants to remove contaminants from soil, has been proposed for treatment of Cd-contaminated ecosystems. In this study, we demonstrated the potential of Vetiveria zizanioides, commonly known as vetiver, to serve as an effective phytoremediation agent. Two ecotypes, i.e., India and Sri Lanka, were grown in greenhouse pots and in the field. Soils were amended with cow manure, pig manure, bat manure, and an organic fertilizer. Among all amendments, pig manure performed best in both greenhouse and field studies in terms of increasing total V. zizanioides biomass production in both ecotypes. In both greenhouse and in the field, tissue of the Sri Lanka ecotype had higher Cd concentrations than did the India ecotype. In the greenhouse, the presence of Cd did not affect total biomass production or root dry weight. The Sri Lanka ecotype had 2.7 times greater adventitious root numbers and 3.6 times greater Cd accumulation in roots than did the India ecotype. In the field study, the Sri Lanka ecotype offers potential as an excluder species, as it accumulated Cd primarily in roots, with translocation factor values <1 and a bioconcentration coefficient for roots >1 for all experiments except for the pig manure amendment. In addition, the highest Cd concentration in the Sri Lanka ecotype root (71.3 mg kg(-1)) was consistent with highest Cd uptake (10.4 mg plant(-1)) in the cow manure treatment. The India ecotype contained lower root Cd concentrations, and Cd accumulation was slightly higher in shoots compared to roots, with translocation factor (TF) values >1. The India ecotype was therefore not considered as an excluder in the Cd-contaminated soil. With the use of excluder species combined with application of organic amendments, soil contamination by Cd may be treated by alternative remediation methods such as phytostabilization.

The interactive impact of root branch order and soil genetic horizon on root respiration and nitrogen concentration.

PubMed

Trocha, Lidia K; Bulaj, Bartosz; Kutczynska, Paulina; Mucha, Joanna; Rutkowski, Pawel; Zadworny, Marcin

2017-08-01

In general, respiration (RS) is highly correlated with nitrogen concentration (N) in plant organs, including roots, which exhibit a positive N-RS relationship. Less is known, however, about the relationship between N and RS in roots of different branch orders within an individual tree along a vertical soil profile; this is especially true in trees with contrasting life strategies, such as pioneer Scots pine (Pinus sylvestris L.) vs mid-successional sessile oak (Quercus petraea Liebl.). In the present research, the impact of root branch order, as represented by those with absorptive vs transporting ability, and soil genetic horizon on root N, RS and the N-RS relationship was examined. Mean RS and total N concentration differed significantly among root branch orders and was significantly higher in absorptive roots than in transporting roots. The soil genetic horizon differentially affected root RS in Scots pine vs sessile oak. The genetic horizon mostly affected RS in absorptive roots of Scots pine and transporting roots in sessile oak. Root N was the highest in absorptive roots and most affected by soil genetic horizon in both tree species. Root N was not correlated with soil N, although N levels were higher in roots growing in fertile soil genetic horizons. Overall, RS in different root branch orders was positively correlated with N in both species. The N-RS relationship in roots, pooled by soil genetic horizon, was significant in both species, but was only significant in sessile oak when roots were pooled by root branch order. In both tree species, a significant interaction was found between the soil genetic horizon and root branch order with root function; however, species-specific responses were found. Both root N, which was unaffected by soil N, and the positive N-RS relationship consistently observed in different genetic horizons suggest that root function prevails over environmental factors, such as soil genetic horizon. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Auxin fluxes in the root apex co-regulate gravitropism and lateral root initiation.

PubMed

Lucas, M; Godin, C; Jay-Allemand, C; Laplaze, L

2008-01-01

Root architecture plays an important role in water and nutrient acquisition and in the ability of the plant to adapt to the soil. Lateral root development is the main determinant of the shape of the root system and is controlled by external factors such as nutrient concentration. Here it is shown that lateral root initiation and root gravitropism, two processes that are regulated by auxin, are co-regulated in Arabidopsis. A mathematical model was generated that can predict the effects of gravistimulations on lateral root initiation density and suggests that lateral root initiation is controlled by an inhibitory fields mechanism. Moreover, gene transactivation experiments suggest a mechanism involving a single auxin transport route for both responses. Finally, co-regulation may offer a selective advantage by optimizing soil exploration as supported by a simple quantitative analysis.

Release of Growth Factors into Root Canal by Irrigations in Regenerative Endodontics.

PubMed

Zeng, Qian; Nguyen, Sean; Zhang, Hongming; Chebrolu, Hari Priya; Alzebdeh, Dalia; Badi, Mustafa A; Kim, Jong Ryul; Ling, Junqi; Yang, Maobin

2016-12-01

The aim of this study was to investigate the release of growth factors into root canal space after the irrigation procedure of regenerative endodontic procedure. Sixty standardized root segments were prepared from extracted single-root teeth. Nail varnish was applied to all surfaces except the root canal surface. Root segments were irrigated with 1.5% NaOCl + 17% EDTA, 2.5% NaOCl + 17% EDTA, 17% EDTA, or deionized water. The profile of growth factors that were released after irrigation was studied by growth factor array. Enzyme-linked immunosorbent assay was used to validate the release of transforming growth factor (TGF)-β1 and basic fibroblast growth factor (bFGF) at 4 hours, 1 day, and 3 days after irrigation. The final concentrations were calculated on the basis of the root canal volume measured by cone-beam computed tomography. Dental pulp stem cell migration on growth factors released from root segments was measured by using Transwell assay. Total of 11 of 41 growth factors were detected by growth factors array. Enzyme-linked immunosorbent assay showed that TGF-β1 was released in all irrigation groups. Compared with the group with 17% EDTA (6.92 ± 4.49 ng/mL), the groups with 1.5% NaOCl + 17% EDTA and 2.5% NaOCl + 17% EDTA had significantly higher release of TGF-β1 (69.04 ± 30.41 ng/mL and 59.26 ± 3.37 ng/mL, respectively), with a peak release at day 1. The release of bFGF was detected at a low level in all groups (0 ng/mL to 0.43 ± 0.22 ng/mL). Migration assay showed the growth factors released from root segments induced dental pulp stem cell migration. The root segment model in present study simulated clinical scenario and indicated that the current irrigation protocol released a significant amount of TGF-β1 but not bFGF. The growth factors released into root canal space induced dental pulp stem cell migration. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

[Effect of selenium on the uptake and translocation of manganese, iron, phosphorus and selenium in rice (Oryza sativa L.)].

PubMed

Hu, Ying; Huang, Yi-Zong; Huang, Yan-Chao; Liu, Yun-Xia; Liang, Jian-Hong

2013-10-01

A pot experiment was conducted to clarify the effect of selenium on the uptake and translocation of manganese (Mn), iron (Fe) , phosphorus (P) and selenium (Se) in rice ( Oryza sativa L.). The results showed that addition of Se led to the significant increase of Se concentration in iron plaque on the root surface, root, shoot, husk and brown rice, and significant decrease of Mn concentration in shoot, husk and brown rice. At the Se concentrations of 0.5 and 1.0 mg.kg-1 in soil, Mn concentrations in rice shoot decreased by 32. 2% and 35.0% respectively, in husk 22.0% and 42.6% , in brown rice 27.5% and 28.5% , compared with the Se-free treatment. There was no significant effect of Se on the P and Fe concentrations in every parts of rice, except for Fe concentrations in husk. The translocation of P and Fe from iron plaque, root, shoot and husk to brown rice was not significantly affected by Se addition, but Mn translocation from iron plaque and root to brown rice was significantly inhibited by Se addition. Addition of 1.0 mg.kg-1. Se resulted in the decrease of translocation factor from iron plaque and root to brown rice by 38.9% and 37.9%, respectively, compared with the control treatment. The distribution ratios of Mn, Fe, P and Se in iron plaque, root, shoot, husk and brown rice were also affected by Se addition. The results indicated that Mn uptake, accumulation and translocation in rice could be decreased by the addition of Se in soil, therefore, Se addition could reduce the Mn harm to human health through food chain.

Influence of light and shoot development stage on leaf photosynthesis and carbohydrate status during the adventitious root formation in cuttings of Corylus avellana L.

PubMed Central

Tombesi, Sergio; Palliotti, Alberto; Poni, Stefano; Farinelli, Daniela

2015-01-01

Adventitious root formation in plant cuttings is influenced by many endogenous and environmental factors. Leaf photosynthesis during rooting of leafy cuttings in hard to root species can contribute to supply carbohydrates to the intensive metabolic processes related to adventious root formation. Light intensity during rooting is artificially kept low to decrease potential cutting desiccation, but can be limiting for photosynthetic activity. Furthermore, leafy cuttings collected from different part of the shoot can have a different ability to fuel adventitious root formation in cutting stem. The aim of this work was to determine the role of leaf photosynthesis on adventitious root formation in hazelnut (Corylus avellana L) (a hard-to-root specie) leafy cuttings and to investigate the possible influence of the shoot developmental stage on cutting rooting and survival in the post-rooting phase. Cutting rooting was closely related to carbohydrate content in cutting stems during the rooting process. Cutting carbohydrate status was positively influenced by leaf photosynthesis during rooting. Non-saturating light exposure of leafy cuttings can contribute to improve photosynthetic activity of leafy cuttings. Collection of cuttings from different part of the mother shoots influenced rooting percentage and this appear related to the different capability to concentrate soluble sugars in the cutting stem during rooting. Adventitious root formation depend on the carbohydrate accumulation at the base of the cutting. Mother shoot developmental stage and leaf photosynthesis appear pivotal factors for adventitious roots formation. PMID:26635821

Interference of allelopathic wheat with different weeds.

PubMed

Zhang, Song-Zhu; Li, Yong-Hua; Kong, Chui-Hua; Xu, Xiao-Hua

2016-01-01

Interference of allelopathic wheat with weeds involves a broad spectrum of species either independently or synergistically with competitive factors. This study examined the interference of allelopathic wheat with 38 weeds in relation to the production of allelochemical 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) in wheat with and without root-root interactions. There were substantial differences in weed biomass and DIMBOA concentration in wheat-weed coexisting systems. Among 38 weeds, nine weeds were inhibited significantly by allelopathic wheat but the other 29 weeds were not. DIMBOA levels in wheat varied greatly with weed species. There was no significant relationship between DIMBOA levels and weed suppression effects. Root segregation led to great changes in weed inhibition and DIMBOA level. Compared with root contact, the inhibition of eight weeds was lowered significantly, while significantly increased inhibition occurred in 11 weeds with an increased DIMBOA concentration under root segregation. Furthermore, the production of DIMBOA in wheat was induced by the root exudates from weeds. Interference of allelopathic wheat with weeds not only is determined by the specificity of the weeds but also depends on root-root interactions. In particular, allelopathic wheat may detect certain weeds through the root exudates and respond by increasing the allelochemical, resulting in weed identity recognition. © 2015 Society of Chemical Industry.

The roles of protein and lipid in the accumulation and distribution of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in plants grown in biosolids-amended soils.

PubMed

Wen, Bei; Wu, Yali; Zhang, Hongna; Liu, Yu; Hu, Xiaoyu; Huang, Honglin; Zhang, Shuzhen

2016-09-01

The roles of protein and lipid in the accumulation and distribution of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in seven species of plants from biosolids-amended soils were investigated. The PFOS and PFOA root concentration factors (Croot/Csoil) ranged from 1.37 to 4.68 and 1.69 to 10.3 (ng/groot)/(ng/gsoil), respectively, while the translocation factors (Cshoot/Croot) ranged from 0.055 to 0.16 and 0.093 to 1.8 (ng/gshoot)/(ng/groot), respectively. The PFOS and PFOA accumulations in roots correlated positively with root protein contents (P < 0.05), while negatively with root lipid contents (P < 0.05). These suggested the promotion effects of protein and inhibition effects of lipid on root uptake. The translocation factors correlated positively with the ratios between protein contents in shoots to those in roots (P < 0.05), showing the importance of protein on PFOS and PFOA translocation. This study is the first to reveal the different roles of protein and lipid in the accumulation and distribution of PFOS and PFOA in plants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Some seasonal carbohydrate fluctuations in coppiced rootstocks of Platanus occidentalis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blum, M.R.; Steinbeck, K.

Carbohydrate concentrations were determined in 11-year-old rootstocks of American sycamore (Platanus occidentalis) which had been coppiced on one- or two-year rotations for the preceding eight years. Sixty rootstocks were destructively sampled periodically between September 1976 and April 1977. Root starch concentrations declined erratically from 21 percent of dry weight in autumn to 14 percent by late April. Sugar levels rose from 1.5 percent in autumn to 5 percent in winter and declined to 3 percent in spring. Considerable variation in root starch levels from tree to tree was observed, and differences in starch and sugar concentrations between rootstocks coppiced onmore » an annual or biannual basis were unimportant. These data suggest that while differences in above-ground biomass yields encountered in short rotation coppice forestry are not due to differences in rootstocks carbohydrate concentrations, the total quantity of reserve carbohydrate stored in a root system is probably a controlling factor for sprout regrowth potential.« less

Atmospheric Direct Uptake and Long-term Fate of Radiocesium in Trees after the Fukushima Nuclear Accident

NASA Astrophysics Data System (ADS)

Mahara, Yasunori; Ohta, Tomoko; Ogawa, Hideki; Kumata, Atsushi

2014-11-01

Large areas of forests were radioactively contaminated by the Fukushima nuclear accident of 2011, and forest decontamination is now an important problem in Japan. However, whether trees absorb radioactive fallout from soil via the roots or directly from the atmosphere through the bark and leaves is unclear. We measured the uptake of radiocesium by trees in forests heavily contaminated by the Fukushima nuclear accident. The radiocesium concentrations in sapwood of two tree species, the deciduous broadleaved konara (Quercus serrata) and the evergreen coniferous sugi (Cryptomeria japonica), were higher than that in heartwood. The concentration profiles showed anomalous directionality in konara and non-directionality in sugi, indicating that most radiocesium in the tree rings was directly absorbed from the atmosphere via bark and leaves rather than via roots. Numerical modelling shows that the maximum 137Cs concentration in the xylem of konara will be achieved 28 years after the accident. Conversely, the values for sugi will monotonously decrease because of the small transfer factor in this species. Overall, xylem 137Cs concentrations will not be affected by root uptake if active root systems occur 10 cm below the soil.

Atmospheric Direct Uptake and Long-term Fate of Radiocesium in Trees after the Fukushima Nuclear Accident

PubMed Central

Mahara, Yasunori; Ohta, Tomoko; Ogawa, Hideki; Kumata, Atsushi

2014-01-01

Large areas of forests were radioactively contaminated by the Fukushima nuclear accident of 2011, and forest decontamination is now an important problem in Japan. However, whether trees absorb radioactive fallout from soil via the roots or directly from the atmosphere through the bark and leaves is unclear. We measured the uptake of radiocesium by trees in forests heavily contaminated by the Fukushima nuclear accident. The radiocesium concentrations in sapwood of two tree species, the deciduous broadleaved konara (Quercus serrata) and the evergreen coniferous sugi (Cryptomeria japonica), were higher than that in heartwood. The concentration profiles showed anomalous directionality in konara and non-directionality in sugi, indicating that most radiocesium in the tree rings was directly absorbed from the atmosphere via bark and leaves rather than via roots. Numerical modelling shows that the maximum 137Cs concentration in the xylem of konara will be achieved 28 years after the accident. Conversely, the values for sugi will monotonously decrease because of the small transfer factor in this species. Overall, xylem 137Cs concentrations will not be affected by root uptake if active root systems occur 10 cm below the soil. PMID:25409781

A worldview of root traits: the influence of ancestry, growth form, climate and mycorrhizal association on the functional trait variation of fine-root tissues in seed plants.

PubMed

Valverde-Barrantes, Oscar J; Freschet, Grégoire T; Roumet, Catherine; Blackwood, Christopher B

2017-09-01

Fine-root traits play key roles in ecosystem processes, but the drivers of fine-root trait diversity remain poorly understood. The plant economic spectrum (PES) hypothesis predicts that leaf and root traits evolved in coordination. Mycorrhizal association type, plant growth form and climate may also affect root traits. However, the extent to which these controls are confounded with phylogenetic structuring remains unclear. Here we compiled information about root and leaf traits for > 600 species. Using phylogenetic relatedness, climatic ranges, growth form and mycorrhizal associations, we quantified the importance of these factors in the global distribution of fine-root traits. Phylogenetic structuring accounts for most of the variation for all traits excepting root tissue density, with root diameter and nitrogen concentration showing the strongest phylogenetic signal and specific root length showing intermediate values. Climate was the second most important factor, whereas mycorrhizal type had little effect. Substantial trait coordination occurred between leaves and roots, but the strength varied between growth forms and clades. Our analyses provide evidence that the integration of roots and leaves in the PES requires better accounting of the variation in traits across phylogenetic clades. Inclusion of phylogenetic information provides a powerful framework for predictions of belowground functional traits at global scales. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Multimedia models of human exposure to industrial emissions through food products: Identifying the critical pathways

DOE Office of Scientific and Technical Information (OSTI.GOV)

McKone, T.E.; Maddalena, R.L.; Dowdy, D.L.

1995-12-31

The magnitude of potential human exposure through foods can be and has been assessed through food-product samples. Reducing these exposures requires that measuring not only the exposure media (food) concentrations but also defining the processes that link various contaminant sources to food. The authors present here a general approach for quantifying human exposure to contaminants in home-grown foods using four factors-ambient environmental concentrations in air and soil; bioconcentration factors between air, soil, leaves, and roots; translocations from leaves and roots to edible-plant parts; and human activity patterns associated with consumption of home-grown food products. The authors combined these factors inmore » a general model and used sensitivity analyses to assess the important contributions to the imprecision of exposure estimates. Despite large uncertainties about human activities, they found the major source of uncertainty (variance) in exposure estimates is attributable to imprecision in quantifying bioconcentration. This is especially evident for persistent and fat-soluble compounds--such as PCBs, PAHs, dioxins, and furans. The evaluation of analytical and theoretical methods used to characterize bioconcentration factors reveals that molecular connectivity indices (MCIs) based on molecular structure are better predictors of bioconcentration in plants than are the solubility factors currently in use. The authors describe ongoing laboratory experiments in exposure chambers with garden foods such as leafy vegetables and root crops. They then assess the ability of these methods to better define chemical mass transfers among the components of the home-garden system-air, soil-organic phases, soil solution, plant roots, and plant leaves.« less

Effects of cadmium on bioaccumulation and biochemical stress response in rice (Oryza sativa L.).

PubMed

Xie, Pan-pan; Deng, Juan-wei; Zhang, Hui-min; Ma, You-hua; Cao, De-ju; Ma, Ru-xiao; Liu, Ren-jing; Liu, Cheng; Liang, Yue-gan

2015-12-01

This study investigated the effects of various Cd concentrations on the bioaccumulation, antioxidative defense, and stress responses of rice (Oryza sativa L.). The distribution characteristics of Cd in rice were in the following order: roots>stems>grains. The bioconcentration factor values of Cd increased at concentrations lower than 3.00 mg Cd/kg and approximately decreased to a constant value at concentrations higher than 3.00 mg Cd/kg. Rice showed a higher Cd accumulation potential at low Cd concentrations than at high Cd concentrations. The Freundlich isotherm model described well the adsorption isotherms of Cd in rice roots. The biosorption mechanism of rice roots was determined to be cooperative adsorption. The malondialdehyde (MDA) content increased at a concentration range of 0.00-5.00 mg/L, indicating the enhancement of lipid peroxidation. By contrast, the MDA content slightly decreased at concentrations higher than 5.00 mg/L. Peroxidase (POD) activity exhibited active response to oxidative stress at concentrations lower than 5.00 mg/L but was inhibited at concentrations higher than 5.00 mg/L. The response to Cd stress of the N-H, O-H and C-O functional groups in rice shoots was observed via Fourier transform infrared spectroscopy. Copyright © 2015 Elsevier Inc. All rights reserved.

Plant traits and decomposition: are the relationships for roots comparable to those for leaves?

PubMed Central

Birouste, Marine; Kazakou, Elena; Blanchard, Alain; Roumet, Catherine

2012-01-01

Background and Aims Fine root decomposition is an important determinant of nutrient and carbon cycling in grasslands; however, little is known about the factors controlling root decomposition among species. Our aim was to investigate whether interspecific variation in the potential decomposition rate of fine roots could be accounted for by root chemical and morphological traits, life history and taxonomic affiliation. We also investigated the co-ordinated variation in root and leaf traits and potential decomposition rates. Methods We analysed potential decomposition rates and the chemical and morphological traits of fine roots on 18 Mediterranean herbaceous species grown in controlled conditions. The results were compared with those obtained for leaves in a previous study conducted on similar species. Key Results Differences in the potential decomposition rates of fine roots between species were accounted for by root chemical composition, but not by morphological traits. The root potential decomposition rate varied with taxonomy, but not with life history. Poaceae, with high cellulose concentration and low concentrations of soluble compounds and phosphorus, decomposed more slowly than Asteraceae and Fabaceae. Patterns of root traits, including decomposition rate, mirrored those of leaf traits, resulting in a similar species clustering. Conclusions The highly co-ordinated variation of roots and leaves in terms of traits and potential decomposition rate suggests that changes in the functional composition of communities in response to anthropogenic changes will strongly affect biogeochemical cycles at the ecosystem level. PMID:22143881

Analysis of the relationship between rusty root incidences and soil properties in Panax ginseng

NASA Astrophysics Data System (ADS)

Wang, Q. X.; Xu, C. L.; Sun, H.; Ma, L.; Li, L.; Zhang, D. D.; Zhang, Y. Y.

2016-08-01

Rusty root is a serious problem in ginseng cultivation that limits the production and quality of ginseng worldwide. The Changbai Mountains are the most famous area for ginseng cultivation in China. To clarify the relationship between rusty root and soil characteristics, physico-chemical properties and enzymatic activities of soil collected from five different fields in the Changbai Mountains were analyzed and a controlled experiment carried out by increasing the concentration of Fe (II). Soil bulk density, moisture, total iron (Fe) and total manganese (Mn) concentrations and polyphenol oxidase (PPO) activity were significantly higher in rusty root than healthy root groups (two-sample test, P<0.05 or P<0.01), respectively. Pearson test showed that there was a significant positive correlation between rusty root index and pH, N, Fe, Mn, Al, Zn and Ca of soil samples collected from fields (P<0.05 or P<0.01), and a significant positive correlation also occurred between rusty root index and Fe (II) added to soil in Fe (II) inducing rusty root (P<0.01). Physiological factors may be very important roles giving rise to ginseng rusty root. Fe (III) reduction and Fe (II) oxidation could be important in increasing the incidence of rusty root. Soil moisture and bulk density of non-rhizosphere soil not attached to the root surface, and pH, N and PPO content of rhizosphere soils attached to the root surface were heavily involved in the reduction, oxidation and sequestration of metal ions.

Contribution of constitutive characteristics of lipids and phenolics in roots of tree species in Myrtales to aluminum tolerance.

PubMed

Maejima, Eriko; Osaki, Mitsuru; Wagatsuma, Tadao; Watanabe, Toshihiro

2017-05-01

High aluminum (Al) concentration in soil solution is the most important factor restricting plant growth in acidic soils. However, various plant species naturally grow in such soils. Generally, they are highly tolerant to Al, but organic acid exudation, the most common Al tolerance mechanism, cannot explain their tolerance. Lower phospholipid and higher sterol proportions in root plasma membrane enhance Al tolerance. Other cellular components, such as cell walls and phenolics, may also be involved in Al tolerance mechanisms. In this study, the relationships between these cellular components and the Al tolerance mechanisms in Melastoma malabathricum and Melaleuca cajuputi, both highly Al-tolerant species growing in strongly acidic soils, were investigated. Both species contained lower proportions of phospholipids and higher proportions of sterols in roots, respectively. Concentrations of phenolics in roots of both species were higher than that of rice; their phenolics could form chelates with Al. In these species, phenolic concentrations and composition were the same irrespective of the presence or absence of Al in the medium, suggesting that a higher concentration of phenolics is not a physiological response to Al but a constitutive characteristic. These characteristics of cellular components in roots may be cooperatively involved in their high Al tolerance. © 2016 The Authors. Physiologia Plantarum published by John Wiley & Sons Ltd on behalf of Scandinavian Plant Physiology Society.

Changes in fine-root production, phenology and spatial distribution in response to N application in irrigated sweet cherry trees.

PubMed

Artacho, Pamela; Bonomelli, Claudia

2016-05-01

Factors regulating fine-root growth are poorly understood, particularly in fruit tree species. In this context, the effects of N addition on the temporal and spatial distribution of fine-root growth and on the fine-root turnover were assessed in irrigated sweet cherry trees. The influence of other exogenous and endogenous factors was also examined. The rhizotron technique was used to measure the length-based fine-root growth in trees fertilized at two N rates (0 and 60 kg ha(-1)), and the above-ground growth, leaf net assimilation, and air and soil variables were simultaneously monitored. N fertilization exerted a basal effect throughout the season, changing the magnitude, temporal patterns and spatial distribution of fine-root production and mortality. Specifically, N addition enhanced the total fine-root production by increasing rates and extending the production period. On average, N-fertilized trees had a length-based production that was 110-180% higher than in control trees, depending on growing season. Mortality was proportional to production, but turnover rates were inconsistently affected. Root production and mortality was homogeneously distributed in the soil profile of N-fertilized trees while control trees had 70-80% of the total fine-root production and mortality concentrated below 50 cm depth. Root mortality rates were associated with soil temperature and water content. In contrast, root production rates were primarily under endogenous control, specifically through source-sink relationships, which in turn were affected by N supply through changes in leaf photosynthetic level. Therefore, exogenous and endogenous factors interacted to control the fine-root dynamics of irrigated sweet cherry trees. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Changes in fine-root production, phenology and spatial distribution in response to N application in irrigated sweet cherry trees

PubMed Central

Artacho, Pamela; Bonomelli, Claudia

2016-01-01

Factors regulating fine-root growth are poorly understood, particularly in fruit tree species. In this context, the effects of N addition on the temporal and spatial distribution of fine-root growth and on the fine-root turnover were assessed in irrigated sweet cherry trees. The influence of other exogenous and endogenous factors was also examined. The rhizotron technique was used to measure the length-based fine-root growth in trees fertilized at two N rates (0 and 60 kg ha−1), and the above-ground growth, leaf net assimilation, and air and soil variables were simultaneously monitored. N fertilization exerted a basal effect throughout the season, changing the magnitude, temporal patterns and spatial distribution of fine-root production and mortality. Specifically, N addition enhanced the total fine-root production by increasing rates and extending the production period. On average, N-fertilized trees had a length-based production that was 110–180% higher than in control trees, depending on growing season. Mortality was proportional to production, but turnover rates were inconsistently affected. Root production and mortality was homogeneously distributed in the soil profile of N-fertilized trees while control trees had 70–80% of the total fine-root production and mortality concentrated below 50 cm depth. Root mortality rates were associated with soil temperature and water content. In contrast, root production rates were primarily under endogenous control, specifically through source–sink relationships, which in turn were affected by N supply through changes in leaf photosynthetic level. Therefore, exogenous and endogenous factors interacted to control the fine-root dynamics of irrigated sweet cherry trees. PMID:26888890

Inhibitory effects of Turkish folk remedies on inflammatory cytokines: interleukin-1alpha, interleukin-1beta and tumor necrosis factor alpha.

PubMed

Yeşilada, E; Ustün, O; Sezik, E; Takaishi, Y; Ono, Y; Honda, G

1997-09-01

In this study, in vitro inhibitory effects of 55 extracts or fractions obtained from 10 plant species on interleukin-1 (IL-1alpha, IL-1beta) and tumor necrosis factor (TNF-alpha) biosynthesis were studied. The following plant materials from Turkish folk medicine for the treatment of various diseases which are thought to be inflammatory in nature e.g. rheumatism, fever, infections, edemas or related inflammatory diseases were selected as the subject of this study: Cistus laurifolius leaves, Clematis flammna flowering herbs, Crataegus orientalis roots, Daphne oleoides ssp. oleoides whole plant, Ecbalium elaterium roots, Rosa canina roots, Rubus discolor roots, Rubus hirtus roots, Sambucus ebulus flowers and leaves, Sambucus nigra flowers and leaves. All plants showed inhibitory activity against at least one of these models in various percentages depending upon the concentration, thus supporting the folkloric utilization. Daphne oleoides was found to be the most active plant against the test models.

Influence of root-bed size on the response of tobacco to elevated CO2 as mediated by cytokinins

PubMed Central

Schaz, Ulrike; Düll, Barbara; Reinbothe, Christiane; Beck, Erwin

2014-01-01

The extent of growth stimulation of C3 plants by elevated CO2 is modulated by environmental factors. Under optimized environmental conditions (high light, continuous water and nutrient supply, and others), we analysed the effect of an elevated CO2 atmosphere (700 ppm, EC) and the importance of root-bed size on the growth of tobacco. Biomass production was consistently higher under EC. However, the stimulation was overridden by root-bed volumes that restricted root growth. Maximum growth and biomass production were obtained at a root bed of 15 L at ambient and elevated CO2 concentrations. Starting with seed germination, the plants were strictly maintained under ambient or elevated CO2 until flowering. Thus, the well-known acclimation effect of growth to enhanced CO2 did not occur. The relative growth rates of EC plants exceeded those of ambient-CO2 plants only during the initial phases of germination and seedling establishment. This was sufficient for a persistently higher absolute biomass production by EC plants in non-limiting root-bed volumes. Both the size of the root bed and the CO2 concentration influenced the quantitative cytokinin patterns, particularly in the meristematic tissues of shoots, but to a smaller extent in stems, leaves and roots. In spite of the generally low cytokinin concentrations in roots, the amounts of cytokinins moving from the root to the shoot were substantially higher in high-CO2 plants. Because the cytokinin patterns of the (xylem) fluid in the stems did not match those of the shoot meristems, it is assumed that cytokinins as long-distance signals from the roots stimulate meristematic activity in the shoot apex and the sink leaves. Subsequently, the meristems are able to synthesize those phytohormones that are required for the cell cycle. Root-borne cytokinins entering the shoot appear to be one of the major control points for the integration of various environmental cues into one signal for optimized growth. PMID:24790131

Occurrence, distribution and bioaccumulation behaviour of hydrophobic organic contaminants in a large-scale constructed wetland in Singapore.

PubMed

Wang, Qian; Kelly, Barry C

2017-09-01

This study involved a field-based investigation to assess the occurrence, distribution and bioaccumulation behaviour of hydrophobic organic contaminants in a large-scale constructed wetland. Samples of raw leachate, water and wetland plants, Typha angustifolia, were collected for chemical analysis. Target contaminants included polychlorinated biphenyls (PCBs), organochlorine pesticides (OCP), as well as several halogenated flame retardants (HFRs) and personal care products (triclosan and synthetic musks). In addition to PCBs and OCPs, synthetic musks, triclosan (TCS) and dechlorane plus stereoisomers (syn- and anti-DPs) were frequently detected. Root concentration factors (log RCF L/kg wet weight) of the various contaminants ranged between 3.0 and 7.9. Leaf concentration factors (log LCF L/kg wet weight) ranged between 2.4 and 8.2. syn- and anti-DPs exhibited the greatest RCF and LCF values. A strong linear relationship was observed between log RCF and octanol-water partition coefficient (log K OW ). Translocation factors (log TFs) were negatively correlated with log K OW . The results demonstrate that more hydrophobic compounds exhibit higher degrees of partitioning into plant roots and are less effectively transported from roots to plant leaves. Methyl triclosan (MTCS) and 2,8-dichlorodibenzo-p-dioxin (DCDD), TCS degradation products, exhibited relatively high concentrations in roots and leaves., highlighting the importance of degradation/biotransformation. The results further suggest that Typha angustifolia in this constructed wetland can aid the removal of hydrophobic organic contaminants present in this landfill leachate. The findings will aid future investigations regarding the fate and bioaccumulation of hydrophobic organic contaminants in constructed wetlands. Copyright © 2017 Elsevier Ltd. All rights reserved.

Platelet-rich-fibrin: A novel root coverage approach

PubMed Central

Anilkumar, K.; Geetha, A.; Umasudhakar; Ramakrishnan, T; Vijayalakshmi, R; Pameela, E.

2009-01-01

Treatment of gingival recession has become an important therapeutic issue due to increasing cosmetic demand. Multiple surgical procedures have been developed to obtain predictable esthetic root coverage. More specifically, after periodontal regenerative surgery, the aim is to achieve complete wound healing and regeneration of the periodontal unit. A recent innovation in dentistry is the preparation and use of platelet-rich plasma (PRP), a concentrated suspension of the growth factors, found in platelets. These growth factors are involved in wound healing and postulated as promoters of tissue regeneration. This paper reports the use of PRF membrane for root coverage on the labial surfaces of the mandibular anterior teeth. This was accomplished using laterally displaced flap technique with platelet rich fibrin (PRF) membrane at the recipient site. PMID:20376243

Changes in bioaccumulation and translocation patterns between root and leafs of Avicennia schaueriana as adaptive response to different levels of metals in mangrove system.

PubMed

Souza, Iara da C; Rocha, Lívia D; Morozesk, Mariana; Bonomo, Marina M; Arrivabene, Hiulana P; Duarte, Ian D; Furlan, Larissa M; Monferrán, Magdalena V; Mazik, Krysia; Elliott, Michael; Matsumoto, Silvia T; Milanez, Camilla R D; Wunderlin, Daniel A; Fernandes, Marisa N

2015-05-15

Espírito Santo estuaries (Brazil) are impacted by industrial activities, resulting in contamination of water and sediments. This raise questions on biological uptake, storage and consequences of metal contamination to mangrove plants. The goal of this work was evaluating accumulation and translocation of metals from sediment to roots and leaves of Avicennia schaueriana, growing in areas with different degrees of contamination, correlating bioaccumulation with changes in its root anatomy. Highest bioconcentration factors (BCFs) were observed in plants growing in less polluted areas. Conversely, highest translocation factors were found in plants from highest polluted area, evidencing an adaptive response of A. schaueriana to less favourable conditions. Namely, the absorption of metals by roots is diminished when facing highest levels of metals in the environment; alternatively, plants seem to enhance the translocation to diminish the concentration of toxic metals in roots. Root also responded to highly polluted scenarios with modifications of its anatomy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Phytoextraction with Salix viminalis in a moderately to strongly contaminated area.

PubMed

Tőzsér, Dávid; Harangi, Sándor; Baranyai, Edina; Lakatos, Gyula; Fülöp, Zoltán; Tóthmérész, Béla; Simon, Edina

2018-02-01

We tested the suitability of Salix viminalis for phytoextraction with the analysis of selected elements in soil, root, and leaf, and by visual tree condition assessment in an area with varying levels of contamination. Bioconcentration factor (BCF) and translocation factor (TF) were used to assess the phytoextraction potential of willows. The middle part of the study area was strongly contaminated, while the northern and southern parts were moderately contaminated. We found increasing element concentrations toward deeper layers. Mean concentrations of elements in roots were similar among the three parts, while in leaves the highest concentrations were found in the strongly contaminated part of the study area. Tree condition scores were the lowest in the strongly contaminated part of the study area, which was caused by Al, Ca, K, Mg, Ni, Sr, and Zn concentration. These elements induced leaf disease and leaf feeders. The highest BCF values were found for Cu, Fe, Mn, and Zn in root, and for Cd and Zn in leaves, indicating that S. viminalis had high accumulation potential of these elements. Furthermore, TF values were high for Cd, Mn, Sr, and Zn. Our results also demonstrated that soil element composition has major influence on the condition of S. viminalis individuals. Furthermore, visual condition assessment was found to be a useful tool to assess the phytoextraction potential of trees.

Root Zone Respiration on Hydroponically Grown Wheat Plant Systems

NASA Technical Reports Server (NTRS)

Soler-Crespo, R. A.; Monje, O. A.

2010-01-01

Root respiration is a biological phenomenon that controls plant growth and physiological development during a plant's lifespan. This process is dependent on the availability of oxygen in the system where the plant is located. In hydroponic systems, where plants are submerged in a solution containing vital nutrients but no type of soil, the availability of oxygen arises from the dissolved oxygen concentration in the solution. This oxygen concentration is dependent on the , gas-liquid interface formed on the upper surface of the liquid, as given by Henry's Law, depending on pressure and temperature conditions. Respiration rates of the plants rise as biomass and root zone increase with age. The respiration rate of Apogee wheat plants (Triticum aestivum) was measured as a function of light intensity (catalytic for photosynthesis) and CO2 concentration to determine their effect on respiration rates. To determine their effects on respiration rate and plant growth microbial communities were introduced into the system, by Innoculum. Surfactants were introduced, simulating gray-water usage in space, as another factor to determine their effect on chemical oxygen demand of microbials and on respiration rates of the plants. It is expected to see small effects from changes in CO2 concentration or light levels, and to see root respiration decrease in an exponential manner with plant age and microbial activity.

The decomposition of fine and coarse roots: their global patterns and controlling factors

PubMed Central

Zhang, Xinyue; Wang, Wei

2015-01-01

Fine root decomposition represents a large carbon (C) cost to plants, and serves as a potential soil C source, as well as a substantial proportion of net primary productivity. Coarse roots differ markedly from fine roots in morphology, nutrient concentrations, functions, and decomposition mechanisms. Still poorly understood is whether a consistent global pattern exists between the decomposition of fine (<2 mm root diameter) and coarse (≥2 mm) roots. A comprehensive terrestrial root decomposition dataset, including 530 observations from 71 sampling sites, was thus used to compare global patterns of decomposition of fine and coarse roots. Fine roots decomposed significantly faster than coarse roots in middle latitude areas, but their decomposition in low latitude regions was not significantly different from that of coarse roots. Coarse root decomposition showed more dependence on climate, especially mean annual temperature (MAT), than did fine roots. Initial litter lignin content was the most important predictor of fine root decomposition, while lignin to nitrogen ratios, MAT, and mean annual precipitation were the most important predictors of coarse root decomposition. Our study emphasizes the necessity of separating fine roots and coarse roots when predicting the response of belowground C release to future climate changes. PMID:25942391

When stress and development go hand in hand: main hormonal controls of adventitious rooting in cuttings

PubMed Central

da Costa, Cibele T.; de Almeida, Márcia R.; Ruedell, Carolina M.; Schwambach, Joseli; Maraschin, Felipe S.; Fett-Neto, Arthur G.

2013-01-01

Adventitious rooting (AR) is a multifactorial response leading to new roots at the base of stem cuttings, and the establishment of a complete and autonomous plant. AR has two main phases: (a) induction, with a requirement for higher auxin concentration; (b) formation, inhibited by high auxin and in which anatomical changes take place. The first stages of this process in severed organs necessarily include wounding and water stress responses which may trigger hormonal changes that contribute to reprogram target cells that are competent to respond to rooting stimuli. At severance, the roles of jasmonate and abscisic acid are critical for wound response and perhaps sink strength establishment, although their negative roles on the cell cycle may inhibit root induction. Strigolactones may also inhibit AR. A reduced concentration of cytokinins in cuttings results from the separation of the root system, whose tips are a relevant source of these root induction inhibitors. The combined increased accumulation of basipetally transported auxins from the shoot apex at the cutting base is often sufficient for AR in easy-to-root species. The role of peroxidases and phenolic compounds in auxin catabolism may be critical at these early stages right after wounding. The events leading to AR strongly depend on mother plant nutritional status, both in terms of minerals and carbohydrates, as well as on sink establishment at cutting bases. Auxins play a central role in AR. Auxin transporters control auxin canalization to target cells. There, auxins act primarily through selective proteolysis and cell wall loosening, via their receptor proteins TIR1 (transport inhibitor response 1) and ABP1 (Auxin-Binding Protein 1). A complex microRNA circuitry is involved in the control of auxin response factors essential for gene expression in AR. After root establishment, new hormonal controls take place, with auxins being required at lower concentrations for root meristem maintenance and cytokinins needed for root tissue differentiation. PMID:23717317

When stress and development go hand in hand: main hormonal controls of adventitious rooting in cuttings.

PubMed

da Costa, Cibele T; de Almeida, Márcia R; Ruedell, Carolina M; Schwambach, Joseli; Maraschin, Felipe S; Fett-Neto, Arthur G

2013-01-01

Adventitious rooting (AR) is a multifactorial response leading to new roots at the base of stem cuttings, and the establishment of a complete and autonomous plant. AR has two main phases: (a) induction, with a requirement for higher auxin concentration; (b) formation, inhibited by high auxin and in which anatomical changes take place. The first stages of this process in severed organs necessarily include wounding and water stress responses which may trigger hormonal changes that contribute to reprogram target cells that are competent to respond to rooting stimuli. At severance, the roles of jasmonate and abscisic acid are critical for wound response and perhaps sink strength establishment, although their negative roles on the cell cycle may inhibit root induction. Strigolactones may also inhibit AR. A reduced concentration of cytokinins in cuttings results from the separation of the root system, whose tips are a relevant source of these root induction inhibitors. The combined increased accumulation of basipetally transported auxins from the shoot apex at the cutting base is often sufficient for AR in easy-to-root species. The role of peroxidases and phenolic compounds in auxin catabolism may be critical at these early stages right after wounding. The events leading to AR strongly depend on mother plant nutritional status, both in terms of minerals and carbohydrates, as well as on sink establishment at cutting bases. Auxins play a central role in AR. Auxin transporters control auxin canalization to target cells. There, auxins act primarily through selective proteolysis and cell wall loosening, via their receptor proteins TIR1 (transport inhibitor response 1) and ABP1 (Auxin-Binding Protein 1). A complex microRNA circuitry is involved in the control of auxin response factors essential for gene expression in AR. After root establishment, new hormonal controls take place, with auxins being required at lower concentrations for root meristem maintenance and cytokinins needed for root tissue differentiation.

Environmental Factors Determining the Accumulation of Metals: Cu, Zn, Mn and Fe in Tissues of Taraxacum sp. sect. Taraxacum.

PubMed

Królak, Elżbieta; Marciniuk, Jolanta; Popijantus, Katarzyna; Wasilczuk, Paulina; Kasprzykowski, Zbigniew

2018-05-19

The genus Taraxacum is used in the assessment of soil contamination with heavy metals. There are relatively few studies using sections or species representing this genus. The presented research was conducted in Poland on two habitats, varied in terms of nutrients and metals content. The content of selected metals in leaves and roots of Taraxacum sect. Taraxacum was determined. It was found that in the conditions of increased content of metals in the soil, the analysed species representing sect. Taraxacum accumulate higher amounts of metals in their leaves and roots. Factors of translocation of selected metals from roots to leaves of Taraxacum species, representing the Taraxacum section, are affected by i.a. soil reaction and the content of Corg, Ntot. in the soil. No influence of soil properties on metal biological concentration factor was observed.

Relationships between root respiration rate and root morphology, chemistry and anatomy in Larix gmelinii and Fraxinus mandshurica.

PubMed

Jia, Shuxia; McLaughlin, Neil B; Gu, Jiacun; Li, Xingpeng; Wang, Zhengquan

2013-06-01

Tree roots are highly heterogeneous in form and function. Previous studies revealed that fine root respiration was related to root morphology, tissue nitrogen (N) concentration and temperature, and varied with both soil depth and season. The underlying mechanisms governing the relationship between root respiration and root morphology, chemistry and anatomy along the root branch order have not been addressed. Here, we examined these relationships of the first- to fifth-order roots for near surface roots (0-10 cm) of 22-year-old larch (Larix gmelinii L.) and ash (Fraxinus mandshurica L.) plantations. Root respiration rate at 18 °C was measured by gas phase O2 electrodes across the first five branching order roots (the distal roots numbered as first order) at three times of the year. Root parameters of root diameter, specific root length (SRL), tissue N concentration, total non-structural carbohydrates (starch and soluble sugar) concentration (TNC), cortical thickness and stele diameter were also measured concurrently. With increasing root order, root diameter, TNC and the ratio of root TNC to tissue N concentration increased, while the SRL, tissue N concentration and cortical proportion decreased. Root respiration rate also monotonically decreased with increasing root order in both species. Cortical tissue (including exodermis, cortical parenchyma and endodermis) was present in the first three order roots, and cross sections of the cortex for the first-order root accounted for 68% (larch) and 86% (ash) of the total cross section of the root. Root respiration was closely related to root traits such as diameter, SRL, tissue N concentration, root TNC : tissue N ratio and stele-to-root diameter proportion among the first five orders, which explained up to 81-94% of variation in the rate of root respiration for larch and up to 83-93% for ash. These results suggest that the systematic variations of root respiration rate within tree fine root system are possibly due to the changes of tissue N concentration and anatomical structure along root branch orders in both tree species, which provide deeper understanding in the mechanism of how root traits affect root respiration in woody plants.

Transfer of wastewater associated pharmaceuticals and personal care products to crop plants from biosolids treated soil.

PubMed

Wu, Chenxi; Spongberg, Alison L; Witter, Jason D; Sridhar, B B Maruthi

2012-11-01

The plant uptake of emerging organic contaminants such as pharmaceuticals and personal care products (PPCPs) is receiving increased attention. Biosolids from municipal wastewater treatment have been previously identified as a major source for PPCPs. Thus, plant uptake of PPCPs from biosolids applied soils needs to be understood. In the present study, the uptake of carbamazepine, diphenhydramine, and triclocarban by five vegetable crop plants was examined in a field experiment. At the time of harvest, three compounds were detected in all plants grown in biosolids-treated soils. Calculated root concentration factor (RCF) and shoot concentration factor (SCF) are the highest for carbamazepine followed by triclocarban and diphenhydramine. Positive correlation between RCF and root lipid content was observed for carbamazepine but not for diphenhydramine and triclocarban. The results demonstrate the ability of crop plants to accumulate PPCPs from contaminated soils. The plant uptake processes of PPCPs are likely affected by their physico-chemical properties, and their interaction with soil. The difference uptake behavior between plant species could not solely be attributed to the root lipid content. Copyright © 2012 Elsevier Inc. All rights reserved.

A literature review and hypothesis for the etiologies of cervical and root caries.

PubMed

Grippo, John O; Coleman, Thomas A; Messina, Antonello Maria; Oh, Daniel S

2018-01-18

The presence of endogenous acids from bacteria acting on a suitable substrate combined with sources of exogenous biocorrosives such as exogenous acids and proteolytic enzymes in areas of stress concentration are hypothesized to lead to the development and progression of cervical and root caries (RC). Quantifying the effects of each of the mechanisms (stress and biocorrosion) is a daunting task to investigate since so many factors are involved at various times in the etiology of noncarious cervical lesions (NCCLs), cervical caries (CC), and RC. Frictional action of the tongue has a cleansing effect and lingual serous saliva, which has a high flow rate buffering capacity from bicarbonates seem to account for the paucity of lingual NCCLs, cervical, and RC in these areas of teeth. Future studies are indicated to determine the effects of stress and biocorrosion and their factors in the etiology of CC and RC. This manuscript presents hypothetical and literary information that the combined effects of stress concentration and biocorrosion contribute to the formation as well as progression of cervical and root caries. © 2018 Wiley Periodicals, Inc.

MICROWAVE-ASSISTED EXTRACTION OF PHENOLIC COMPOUNDS FROM POLYGONUM MULTIFLORUM THUNB. ROOTS.

PubMed

Quoc, Le Pham Tan; Muoi, Nguyen Van

2016-01-01

The aim of this study was to determine the best extraction conditions for total phenolic content (TPC) and antioxidant capacity (AC) of Polygonum multiflorum Thunb. root using microwave-assisted extraction (MAE). The raw material used was Polygonum multiflorum Thunb. root powder. Five factors such as solvent type, solvent concentrations, solvent/material ratio, extraction time and microwave power were studied; TPC and AC values were determined by the Folin-Ciocalteu method and DPPH free radical scavenging activity measurement, respectively. In addition, studies involved assaying the HPLC test of extracts and SEM of samples. Optimal results pointed to acetone as the solvent, acetone concentration of 60%, solvent/material ratio of 40/1 (v/w), extraction time of 5 mins and microwave power of 127 W. TPC and AC obtained were approximates 44.3 ±0.13 mg GAE/g DW and 341.26 ±1.54 μmol TE/g DW, respectively. The effect of microwaving on the cell destruction of Polygonum multiflorum Thunb. root was observed by scanning electron microscopy (SEM). Some phenolic compounds were determined by the HPLC method, for instance, gallic acid, catechin and resveratrol. These factors significantly affected TPC and AC. We can use acetone as a solvent with microwave-assisted extraction to achieve the best result.

The Role of Smoking and Gingival Crevicular Fluid Markers on Coronally Advanced Flap Outcomes

PubMed Central

Kaval, Başak; Renaud, Diane E.; Scott, David A.; Buduneli, Nurcan

2015-01-01

Background This study evaluates possible effects of smoking on the following: 1) biochemical content in gingival crevicular fluid (GCF) samples from sites of gingival recession and saliva; and 2) clinical outcomes of coronally advanced flap (CAF) for root coverage. Methods Eighteen defects in 15 patients were included in each of the smoker and non-smoker groups. Baseline cotinine, basic fibroblast growth factor, vascular endothelial growth factor, platelet-derived growth factor, interleukin (IL)-8, IL-10, IL-12, tumor necrosis factor-α, matrix metalloproteinase (MMP)-8, MMP-9, and plasminogen activator inhibitor-1 levels were determined in GCF and saliva samples. CAF with microsurgery technique was applied. Plaque index, papilla bleeding index, recession depth (RD), recession width (RW), and root surface area were evaluated at baseline and postoperative months 1, 3, and 6. Probing depth, clinical attachment level (CAL), and keratinized gingival width (KGW) was recorded at baseline and month 6. Percentage of root coverage and complete root coverage were calculated at postoperative months 1, 3, and 6. Results All biochemical parameters were similar in the two groups apart from the definite difference in salivary cotinine concentrations (P = 0.000). Compared with the baseline values, RD, RW, CAL, and root surface area decreased, and KGW increased, with no significant difference between the study groups. CAL gain, percentage of root coverage, and complete root-coverage rates were similar in the study groups. Conclusion Similar baseline biochemical data and comparably high success rates of root coverage with CAF in systemically and periodontally healthy smokers versus non-smokers suggest lack of adverse effects of smoking on clinical outcomes. PMID:23725027

Seasonal changes of metal accumulation and distribution in common club rush (Schoenoplectus lacustris) and common reed (Phragmites australis).

PubMed

Duman, Fatih; Cicek, Mehmet; Sezen, Goksal

2007-08-01

In this study, two aquatic macrophytes Phragmites australis and Schoenoplectus lacustris and corresponding sediment samples were collected every three months from Lake Sapanca (Turkey) and analysed for their heavy-metal contents (Pb, Cr, Cu, Mn, Ni, Zn and Cd). Accumulation factor ratios of plant parts were calculated for all metals, and the two species were compared in terms of accumulation properties. The highest concentrations were measured in the root systems while relatively low concentrations were found in the rhizome and above-ground parts of the plants. The accumulation ratios of root for P. australis were usually higher than the ratios for S. lacustris. While the accumulation ratios of root were higher in winter than in the other seasons for P. australis, for S. lacustris the highest accumulation ratios were found in the autumn. Both plant species were found to be root accumulators of Pb, Cu, Mn, Ni, Zn and Cd.

Chemical Interactions of Uranium in Water, Sediments, and Plants Along a Watershed Adjacent to the Abandoned Jackpile Mine

NASA Astrophysics Data System (ADS)

Blake, J.; De Vore, C. L.; Avasarala, S.; Ali, A.; Roldan, C.; Bowers, F.; Spilde, M.; Artyushkova, K.; Cerrato, J.

2015-12-01

The chemical interactions, mobility, and plant uptake of uranium (U) near abandoned mine wastes was investigated along the Rio Paguate, adjacent to the Jackpile Mine, located in Laguna Pueblo, New Mexico. Elevated U concentrations in surface water adjacent to mine waste range from 30 to 710 μg/L seasonally and decrease to 5.77 to 10.0 μg/L at a wetland 4.5 kilometers downstream of the mine. Although U concentrations in stream water are elevated, aqua regia acid digestions performed on co-located stream bed and stream bank sediments reveal that there is limited U accumulation on sediments along the reach between the mine and wetland, with most sediment concentrations being near the 3 mg/kg crustal average. However, U concentrations in sediments in the wetland are 4 times the background concentrations in the area. Individual results from salt cedar roots, stems, and leaves collected along the river transect show higher U concentrations in the roots adjacent to the mine waste (20 and 55 mg/kg) and lower in the stems and leaves. Translocation values calculated below 1 are evident in many of the plant samples, suggesting that U root to shoot translocation is minimal and U is accumulating in the roots. Concentrations of U in salt cedar roots from downstream of the mine waste decrease to 15 mg/kg. X-ray photoelectron spectroscopy analysis on sediment samples adjacent to the mine waste show a 75:25% ratio of Fe(III) to Fe(II), which can have an effect on adsorption properties. Electron microprobe results suggest that the ore in this area is present as a uranium-phosphate phase. Our results suggest that dilution, uptake by plants, and U sorption to wetland sediments are the dominant factors that help to decrease the U concentrations downstream of the mine.

Correlated responses of root growth and sugar concentrations to various defoliation treatments and rhythmic shoot growth in oak tree seedlings (Quercus pubescens)

PubMed Central

Willaume, Magali; Pagès, Loïc

2011-01-01

Background and Aims To understand whether root responses to aerial rhythmic growth and contrasted defoliation treatments can be interpreted under the common frame of carbohydrate availability; root growth was studied in parallel with carbohydrate concentrations in different parts of the root system on oak tree seedlings. Methods Quercus pubescens seedlings were submitted to selective defoliation (removal of mature leaves, cotyledons or young developing leaves) at appearance of the second flush and collected 1, 5 or 10 d later for morphological and biochemical measurements. Soluble sugar and starch concentrations were measured in cotyledons and apical and basal root parts. Key Results Soluble sugar concentration in the root apices diminished during the expansion of the second aerial flush and increased after the end of aerial growth in control seedlings. Starch concentration in cotyledons regularly decreased. Continuous removal of young leaves did not alter either root growth or apical sugar concentration. Starch storage in basal root segments was increased. After removal of mature leaves (and cotyledons), root growth strongly decreased. Soluble sugar concentration in the root apices drastically decreased and starch reserves in the root basal segments were emptied 5 d after defoliation, illustrating a considerable shortage in carbohydrates. Soluble sugar concentrations recovered 10 d after defoliation, after the end of aerial growth, suggesting a recirculation of sugar. No supplementary recourse to starch in cotyledons was observed. Conclusions The parallel between apical sugar concentration and root growth patterns, and the correlations between hexose concentration in root apices and their growth rate, support the hypothesis that the response of root growth to aerial periodic growth and defoliation treatments is largely controlled by carbohydrate availability. PMID:21239407

Influence of summer sowing dates, N fertilization and irrigation on autumn VSP accumulation and dynamics of spring regrowth in alfalfa (Medicago sativa L.).

PubMed

Justes, Eric; Thiébeau, Pascal; Avice, Jean-Christophe; Lemaire, Gilles; Volenec, Jeffrey J; Ourry, Alain

2002-01-01

Herbage yield of alfalfa (Medicago sativa L.) depends on forage management or environmental conditions that change C and N resource acquisition, and endogenous plants factors such as root organic reserves and number of active meristems. The aim of this work is to study the influence of two sowing dates in summer (12 July or 9 August), N fertilization (0 or 100 kg ha(-1)) and/or irrigation applied during the first year of alfalfa establishment on (i) the accumulation of N organic reserves (soluble proteins and more specifically vegetative storage protein) in taproots during autumn, (ii) the number of crown axillary meristems present at the end of winter and (iii) the dynamics of spring shoot growth. Delaying the sowing date for one month reduced root growth and root N storage, especially vegetative storage proteins (VSP) during autumn. Irrespective of sowing dates, N fertilization did not affect root biomass, number of crown buds, total root N, root soluble protein or VSP concentrations. By contrast, water deficiency during alfalfa establishment in the early summer reduced both root growth and N reserve accumulation. When spring growth resumed, there is a significant linear relationship between leaf area development and soluble protein and VSP concentrations in taproots, and also the number of crown buds. The results showed that an early sowing date and adequate water status during the summer allowed alfalfa plants to accumulate N reserves by increasing taproot mass and soluble protein concentrations, especially VSPs. This resulted in rapid shoot regrowth rates the following spring.

Effect of artificial root exudates on the sorption and desorption of PAHs in meadow brown soils

NASA Astrophysics Data System (ADS)

Wang, Hong

2017-10-01

The batch equilibrium experiment was conducted to investigate the effect of artificial root exudates on sorption and desorption of phenanthrene and pyrene. The result showed sorption isotherms were fitted well to the Freundlich equation with the treatment of artificial root exudates. Fructose had the most obvious effect on sorption. The artificial root exudates improved desorption of PAHs, while low molecular weight organic acids were better than serine and fructose. The capability of sorption and desorption was strengthened with the increase of organic acids concentration. And the DOM in the solution might be the most important factor of the adsorption of PAHs in solid phase.

Growth and Cd uptake by rice (Oryza sativa) in acidic and Cd-contaminated paddy soils amended with steel slag.

PubMed

He, Huaidong; Tam, Nora F Y; Yao, Aijun; Qiu, Rongliang; Li, Wai Chin; Ye, Zhihong

2017-12-01

Contamination of rice (Oryza sativa) by Cd is of great concern. Steel slag could be used to amend Cd-contaminated soils and make them safe for cereal production. This work was conducted to study the effects of steel slag on Cd uptake and growth of rice plants in acidic and Cd-contaminated paddy soils and to determine the possible mechanisms behind these effects. Pot (rhizobag) experiments were conducted using rice plants grown on two acidic and Cd-contaminated paddy soils with or without steel slag amendment. Steel slag amendment significantly increased grain yield by 36-45% and root catalase activity, and decreased Cd concentrations in brown rice by 66-77% compared with the control, in both soils. Steel slag amendment also markedly decreased extractable soil Cd, Cd concentrations in pore-water and Cd translocation from roots to above-ground parts. It also significantly increased soil pH, extractable Si and Ca in soils and Ca concentrations in roots. Significant positive correlations were found between extractable soil Cd and Cd concentrations in rice tissues, but it was negatively correlated with soil pH and extractable Si. Calcium in root tissues significantly and negatively correlated with Cd translocation factors from roots to straw. Overall, steel slag amendment not only significantly promoted rice growth but decreased Cd accumulation in brown rice. These benefits appear to be related to improvements in soil conditions (e.g. increasing pH, extractable Si and Ca), a reduction in extractable soil Cd, and suppression of Cd translocation from roots to above-ground parts. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bioaccumulation of metals in plants, arthropods, and mice at a seasonal wetland.

PubMed

Torres, K C; Johnson, M L

2001-11-01

Concentrations of arsenic, cadmium, copper, lead, and nickel were measured in soils, house mice (Mus musculus), and the main food items of this omnivorous mouse to examine the occurrence of these metals in selected components of a seasonal wetland. Soil concentrations of copper, lead, and (in some areas) nickel were elevated, but extractable soil concentrations indicated low bioavailability of metals. Levels of most metals in mice and composited arthropods were consistent with reference site concentrations from other studies. However, copper was found to be particularly mobile within the local ecosystem and accumulated in house mouse carcasses and composited arthropods at substantial levels. Metal residues in Scirpus robustus (alkali bulrush) roots exceeded those in seeds, consistent with patterns of bioaccumulation commonly observed in plants. Uptake and bioaccumulation factors for S. robustus seeds and roots, arthropods, and mouse carcasses and livers are reported. Concentrations of lead and nickel in S. robustus roots exhibited significant linear relationships with levels in soils. Copper levels in S. robustus seeds varied significantly with those in house mouse livers, suggesting that trophic transfer of copper from this food source to mice occurred. However, other spatial patterns of bioaccumulation in S. robustus and house mice relative to soil/seed concentrations were absent. Metal levels in house mice bore no relation to body weight or estimated age.

238U, and its decay products, in grasses from an abandoned uranium mine

NASA Astrophysics Data System (ADS)

Childs, Edgar; Maskall, John; Millward, Geoffrey

2016-04-01

Bioaccumulation of radioactive contaminants by plants is of concern particularly where the sward is an essential part of the diet of ruminants. The abandoned South Terras uranium mine, south west England, had primary deposits of uraninite (UO2) and pitchblende (U3O8), which contained up to 30% uranium. When the mine was active uranium and radium were extracted but following closure it was abandoned without remediation. Waste rock and gangue, consisting of inefficiently processed minerals, were spread around the site, including a field where ruminants are grazed. Here we report the activity concentrations of 238U, 235U 214,210Pb, and the concentrations of selected metals in the soils, roots and leaves of grasses taken from the contaminated field. Soil samples were collected at the surface, and at 30 cm depth, using an auger along a 10-point transect in the field from the foot of a waste heap. Whole, individual grass plants were removed with a spade, ensuring that their roots were intact. The soils and roots and grass leaves were freeze-dried. Activity concentrations of the radionuclides were determined by gamma spectroscopy, following 30 days incubation for development of secular equilibrium. Dried soils, roots and grasses were also digested in aqua regia and the concentrations of elements determined by ICP techniques. Maximum activity concentrations of 238U, 235U, 214Pb and 210Pb surface soils were 63,300, 4,510, 23,300 and 49,400 Bq kg-1, respectively. The mean 238U:235U ratio was 11.8 ± 1.8, an order of magnitude lower than the natural value of 138, indicating disequilibrium within the decay chain due to mineral processing. Radionuclides in the roots had 5 times lower concentration and only grass leaves in the vicinity of the waste heap had measureable values. The mean soil to root transfer factor for 238U was 36%, the mean root to leaf was 3% and overall only 0.7% of 238U was transferred from the soil to the leaves. The roots contained 0.8% iron, possibly as iron plaque acting to mediate 238U transfer within the plants. The results are discussed in the context of remediation of grazing land contaminated with radionuclides.

The effect of iron plaque on lead translocation in soil-Carex cinerascens kukenth. system.

PubMed

Liu, Chunying; Gong, Xiaofeng; Chen, Chunli; Yang, Juyun; Xu, Sheng

2016-01-01

A pot experiment was conducted to investigate the effect of iron plaque on Pb uptake by and translocation in Carex cinerascens Kukenth. grown under open-air conditions. Using Scanning Electron Microscopy and Energy Dispersive X-Ray Spectrometry, iron plaque was present as an amorphous coating on root surfaces with uneven distribution. The amount of iron plaque increased significantly with increasing Fe additions regardless of Pb additions. The presence of iron plaque on the root surface of Carex cinerascens Kukenth. increased the concentrations of Pb adsorbed by iron plaque. The Pb percentage in whole roots increased by 14.52% at 500 mg kg(-1) Fe treatment than at 0 mg kg(-1) Fe, and the distribution coefficient (DC) of Pb and translocation factor (TF) root increased with Fe additions, but translocation factor (TF) shoot decreased with Fe additions. The results suggested that iron plaque could promote the translocation of Pb from soil to roots to some extent, and it played a role to reduce heavy metals pollution of Poyang Lake wetland.

The interaction of heavy metals and nutrients present in soil and native plants with arbuscular mycorrhizae on the riverside in the Matanza-Riachuelo River Basin (Argentina).

PubMed

Mendoza, Rodolfo E; García, Ileana V; de Cabo, Laura; Weigandt, Cristian F; Fabrizio de Iorio, Alicia

2015-02-01

This study assessed the contamination by heavy metals (Cr, Cu, Pb, Zn), and nutrients (N, P) in soils and native plants, and the effect of the concentration of those elements with the density of arbuscular-mycorrhizal (AM) spores in soil and colonization in roots from the riverside of the Matanza-Riachuelo River Basin (MRRB). The concentration of metals and nutrients in soils and plants (Eleocharis montana, Cyperus eragrostis, Hydrocotyle bonariensis) increased from the upper sites (8 km from headwaters) to the lower sites (6 km from the mouth of the Riachuelo River) of the basin. AM-colonization on the roots of H. bonariensis and spore density in soil decreased as the concentrations of metals in soil and plant tissues increased from the upper to lower sites of the basin within a consistent gradient of contamination associated with land use, soil disturbance, population, and chemicals discharged into the streams and rivers along the MRRB. The general trends for all metals in plant tissue were to have highest concentrations in roots, then in rhizomes and lowest in aerial biomass. The translocation (TF) and bioconcentration (BCF) factors decreased in plants which grow from the upper sites to the lower sites of the basin. The plants tolerated a wide range in type and quantity of contamination along the basin by concentrating more metals and nutrients in roots than in aboveground tissue. The AM spore density in soil and colonization in roots of H. bonariensis decreased with the increase of the degree of contamination (Dc) in soil. Copyright © 2014 Elsevier B.V. All rights reserved.

Dissecting the effects of nitrate, sucrose and osmotic potential on Arabidopsis root and shoot system growth in laboratory assays

PubMed Central

Roycewicz, Peter; Malamy, Jocelyn E.

2012-01-01

Studying the specific effects of water and nutrients on plant development is difficult because changes in a single component can often trigger multiple response pathways. Such confounding issues are prevalent in commonly used laboratory assays. For example, increasing the nitrate concentration in growth media alters both nitrate availability and osmotic potential. In addition, it was recently shown that a change in the osmotic potential of media alters the plant's ability to take up other nutrients such as sucrose. It can also be difficult to identify the initial target tissue of a particular environmental cue because there are correlated changes in development of many organs. These growth changes may be coordinately regulated, or changes in development of one organ may trigger changes in development of another organ as a secondary effect. All these complexities make analyses of plant responses to environmental factors difficult to interpret. Here, we review the literature on the effects of nitrate, sucrose and water availability on root system growth and discuss the mechanisms underlying these effects. We then present experiments that examine the impact of nitrate, sucrose and water on root and shoot system growth in culture using an approach that holds all variables constant except the one under analysis. We found that while all three factors also alter root system size, changes in sucrose and osmotic potential also altered shoot system size. In contrast, we found that, when osmotic effects are controlled, nitrate specifically inhibits root system growth while having no effect on shoot system growth. This effectively decreases the root : shoot ratio. Alterations in root : shoot ratio have been widely observed in response to nitrogen starvation, where root growth is selectively increased, but the present results suggest that alterations in this ratio can be triggered across a wide spectrum of nitrate concentrations. PMID:22527391

Genetic and environmental control of seasonal carbohydrate dynamics in trees of diverse Pinus sylvestris populations.

PubMed

Oleksyn, J.; Zytkowiak, R.; Karolewski, P.; Reich, P. B.; Tjoelker, M. G.

2000-06-01

We explored environmental and genetic factors affecting seasonal dynamics of starch and soluble nonstructural carbohydrates in needle and twig cohorts and roots of Scots pine (Pinus sylvestris L.) trees of six populations originating between 49 degrees and 60 degrees N, and grown under common garden conditions in western Poland. Trees of each population were sampled once or twice per month over a 3-year period from age 15 to 17 years. Based on similarity in starch concentration patterns in needles, two distinct groups of populations were identified; one comprised northern populations from Sweden and Russia (59-60 degrees N), and another comprised central European populations from Latvia, Poland, Germany and France (49-56 degrees N). Needle starch concentrations of northern populations started to decline in late spring and reached minimum values earlier than those of central populations. For all populations, starch accumulation in spring started when minimum air temperature permanently exceeded 0 degrees C. Starch accumulation peaked before bud break and was highest in 1-year-old needles, averaging 9-13% of dry mass. Soluble carbohydrate concentrations were lowest in spring and summer and highest in autumn and winter. There were no differences among populations in seasonal pattern of soluble carbohydrate concentrations. Averaged across all populations, needle soluble carbohydrate concentrations increased from about 4% of needle dry mass in developing current-year needles, to about 9% in 1- and 2-year-old needles. Root carbohydrate concentration exhibited a bimodal pattern with peaks in spring and autumn. Northern populations had higher concentrations of fine-root starch in spring and autumn than central populations. Late-summer carbohydrate accumulation in roots started only after depletion of starch in needles and woody shoots. We conclude that Scots pine carbohydrate dynamics depend partially on inherited properties that are probably related to phenology of root and shoot growth.

Degradation of Root Community Traits as Indicator for Transformation of Tropical Lowland Rain Forests into Oil Palm and Rubber Plantations

PubMed Central

Edy, Nur; Meyer, Marike; Corre, Marife D.; Polle, Andrea

2015-01-01

Conversion of tropical forests into intensely managed plantations is a threat to ecosystem functions. On Sumatra, Indonesia, oil palm (Elaeis guineensis) plantations are rapidly expanding, displacing rain forests and extensively used rubber (Hevea brasiliensis) agro-forests. Here, we tested the influence of land use systems on root traits including chemical traits (carbon, nitrogen, mineral nutrients, potentially toxic elements [aluminium, iron] and performance traits (root mass, vitality, mycorrhizal colonization). Traits were measured as root community-weighed traits (RCWTs) in lowland rain forests, in rubber agro-forests mixed with rain forest trees, in rubber and oil palm plantations in two landscapes (Bukit Duabelas and Harapan, Sumatra). We hypothesized that RCWTs vary with land use system indicating increasing transformation intensity and loss of ecosystem functions. The main factors found to be related to increasing transformation intensity were declining root vitality and root sulfur, nitrogen, carbon, manganese concentrations and increasing root aluminium and iron concentrations as well as increasing spore densities of arbuscular mycorrhizas. Mycorrhizal abundance was high for arbuscular and low for ectomycorrhizas and unrelated to changes in RCWTs. The decline in RCWTs showed significant correlations with soil nitrogen, soil pH and litter carbon. Thus, our study uncovered a relationship between deteriorating root community traits and loss of ecosystem functionality and showed that increasing transformation intensity resulted in decreasing root nutrition and health. Based on these results we suggest that land management that improves root vitality may enhance the ecological functions of intense tropical production systems. PMID:26366576

Degradation of Root Community Traits as Indicator for Transformation of Tropical Lowland Rain Forests into Oil Palm and Rubber Plantations.

PubMed

Sahner, Josephine; Budi, Sri Wilarso; Barus, Henry; Edy, Nur; Meyer, Marike; Corre, Marife D; Polle, Andrea

2015-01-01

Conversion of tropical forests into intensely managed plantations is a threat to ecosystem functions. On Sumatra, Indonesia, oil palm (Elaeis guineensis) plantations are rapidly expanding, displacing rain forests and extensively used rubber (Hevea brasiliensis) agro-forests. Here, we tested the influence of land use systems on root traits including chemical traits (carbon, nitrogen, mineral nutrients, potentially toxic elements [aluminium, iron] and performance traits (root mass, vitality, mycorrhizal colonization). Traits were measured as root community-weighed traits (RCWTs) in lowland rain forests, in rubber agro-forests mixed with rain forest trees, in rubber and oil palm plantations in two landscapes (Bukit Duabelas and Harapan, Sumatra). We hypothesized that RCWTs vary with land use system indicating increasing transformation intensity and loss of ecosystem functions. The main factors found to be related to increasing transformation intensity were declining root vitality and root sulfur, nitrogen, carbon, manganese concentrations and increasing root aluminium and iron concentrations as well as increasing spore densities of arbuscular mycorrhizas. Mycorrhizal abundance was high for arbuscular and low for ectomycorrhizas and unrelated to changes in RCWTs. The decline in RCWTs showed significant correlations with soil nitrogen, soil pH and litter carbon. Thus, our study uncovered a relationship between deteriorating root community traits and loss of ecosystem functionality and showed that increasing transformation intensity resulted in decreasing root nutrition and health. Based on these results we suggest that land management that improves root vitality may enhance the ecological functions of intense tropical production systems.

[Effects of soil warming on specific respiration rate and non-structural carbohydrate concentration in fine roots of Chinese fir seedlings].

PubMed

Song, Tao Tao; Chen, Guang Shui; Shi, Shun Zeng; Guo, Run Quan; Zheng, Xin; Xiong, De Cheng; Chen, Wang Yuan; Chen, Ting Ting

2018-03-01

A field mesocosm experiment with Chinese fir (Cunninghamia lanceolata) seedlings was conducted in Chenda State-Owned Forest Farm, Sanming, Fujian Province. The effects of soil warming (ambient +5 ℃) on specific respiration rates and nonstructural carbohydrate (NSC) concentrations in fine roots were measured by the ingrowth core method, to reveal the belowground responses and the adaptability of Chinese fir to global warming. The results showed that soil warming caused significant changes of fine root NSC in the second year. The NSC and starch concentrations in 0-1 mm fine roots, and the NSC and sugar concentrations in 1-2 mm fine roots decreased signifi-cantly in January. The NSC, sugar and starch concentrations in 0-1 mm roots and the starch concentration in 1-2 mm roots increased in July. Soil warming had no significant effect on fine root NSC in the third year. The specific root respiration rate of the 0-1 mm roots significantly increased in July of the second year but significantly decreased in July of the third year in the warmed plots. Compared with the 0-1 mm roots, soil warming had no significant effect on the specific root respiration rate of the 1-2 mm roots. In conclusion, the responses of fine root respiration to soil warming depended on the duration of warming. Fine root respiration partly acclimated to soil warming with increasing duration of soil warming, which kept fine root NSC being relatively stable.

Biomass and nutrient allocation strategies in a desert ecosystem in the Hexi Corridor, northwest China.

PubMed

Zhang, Ke; Su, YongZhong; Yang, Rong

2017-07-01

The allocation of biomass and nutrients in plants is a crucial factor in understanding the process of plant structures and dynamics to different environmental conditions. In this study, we present a comprehensive scaling analysis of data from a desert ecosystem to determine biomass and nutrient (carbon (C), nitrogen (N), and phosphorus (P)) allocation strategies of desert plants from 40 sites in the Hexi Corridor. We found that the biomass and levels of C, N, and P storage were higher in shoots than in roots. Roots biomass and nutrient storage were concentrated at a soil depth of 0-30 cm. Scaling relationships of biomass, C storage, and P storage between shoots and roots were isometric, but that of N storage was allometric. Results of a redundancy analysis (RDA) showed that soil nutrient densities were the primary factors influencing biomass and nutrient allocation, accounting for 94.5% of the explained proportion. However, mean annual precipitation was the primary factor influencing the roots biomass/shoots biomass (R/S) ratio. Furthermore, Pearson's correlations and regression analyses demonstrated that although the biomass and nutrients that associated with functional traits primarily depended on soil conditions, mean annual precipitation and mean annual temperature had greater effects on roots biomass and nutrient storage.

Salinization of the soil solution decreases the further accumulation of salt in the root zone of the halophyte Atriplex nummularia Lindl. growing above shallow saline groundwater.

PubMed

Alharby, Hesham F; Colmer, Timothy D; Barrett-Lennard, Edward G

2018-01-01

Water use by plants in landscapes with shallow saline groundwater may lead to the accumulation of salt in the root zone. We examined the accumulation of Na + and Cl - around the roots of the halophyte Atriplex nummularia Lindl. and the impacts of this increasing salinity for stomatal conductance, water use and growth. Plants were grown in columns filled with a sand-clay mixture and connected at the bottom to reservoirs containing 20, 200 or 400 mM NaCl. At 21 d, Na + and Cl - concentrations in the soil solution were affected by the salinity of the groundwater, height above the water table and the root fresh mass density at various soil depths (P < 0.001). However, by day 35, the groundwater salinity and height above the water table remained significant factors, but the root fresh mass density was no longer significant. Regression of data from the 200 and 400 mM NaCl treatments showed that the rate of Na + accumulation in the soil increased until the Na + concentration reached ~250 mM within the root zone; subsequent decreases in accumulation were associated with decreases in stomatal conductance. Salinization of the soil solution therefore had a feedback effect on further salinization within the root zone. © 2017 John Wiley & Sons Ltd.

Physiological and molecular analysis of the interaction between aluminium toxicity and drought stress in common bean (Phaseolus vulgaris)

PubMed Central

Yang, Zhong-Bao; Eticha, Dejene; Albacete, Alfonso; Rao, Idupulapati Madhusudana; Roitsch, Thomas; Horst, Walter Johannes

2012-01-01

Aluminium (Al) toxicity and drought are two major factors limiting common bean (Phaseolus vulgaris) production in the tropics. Short-term effects of Al toxicity and drought stress on root growth in acid, Al-toxic soil were studied, with special emphasis on Al–drought interaction in the root apex. Root elongation was inhibited by both Al and drought. Combined stresses resulted in a more severe inhibition of root elongation than either stress alone. This result was different from the alleviation of Al toxicity by osmotic stress (–0.60 MPa polyethylene glycol) in hydroponics. However, drought reduced the impact of Al on the root tip, as indicated by the reduction of Al-induced callose formation and MATE expression. Combined Al and drought stress enhanced up-regulation of ACCO expression and synthesis of zeatin riboside, reduced drought-enhanced abscisic acid (ABA) concentration, and expression of NCED involved in ABA biosynthesis and the transcription factors bZIP and MYB, thus affecting the regulation of ABA-dependent genes (SUS, PvLEA18, KS-DHN, and LTP) in root tips. The results provide circumstantial evidence that in soil, drought alleviates Al injury, but Al renders the root apex more drought-sensitive, particularly by impacting the gene regulatory network involved in ABA signal transduction and cross-talk with other phytohormones necessary for maintaining root growth under drought. PMID:22371077

Allelochemicals in rye (Secale cereale L.): cultivar and tissue differences in the production of benzoxazinoids and phenolic acids.

PubMed

Carlsen, Sandra C K; Kudsk, Per; Laursen, Bente; Mathiassen, Solvejg K; Mortensen, Anne G; Fomsgaard, Inge S

2009-02-01

In the present study, a range of benzoxazinoid compounds and phenolic acids, all known to be allelochemicals of rye, were identified and quantified in 13 rye cultivars grown at three different localities. Plant samples were collected in the spring at the time when an autumn-sown rye cover crop would be incorporated into the soil. Significant variations in content among shoots and roots were seen for all of the secondary metabolites, with non-methoxy-substituted benzoxazinoids (BX) dominating the shoots, whereas comparable levels were found in the concentrations of BX and methoxy-substituted benzoxazinoids (MBX) in the roots. This distribution of compounds may indicate different biosynthetic pathways and/or different mechanisms of action of these compounds. Concentrations not only depended on plant part, but also on the geographical location--with differences in contents of up to a factor of 5. These differences can probably be attributed to differences in growing conditions. The variation among cultivars was similar to that among geographical localities, with differences within localities of up to a factor of 7 in the shoots and a factor of 14 in the roots. In roots, the contents of the four phenolic acids and the benzoxazinoid 6-methoxybenzoxazolin-2-one (MBOA) were correlated. In shoots, the contents of the two benzoic acids were correlated with each other, whereas the two cinnamic acids were correlated with MBOA and several other benzoxazinoids. The lack of correlation between MBOA and all other benzoxazinoids in the roots of rye might indicate that a hitherto unknown synthetic pathway exists for MBOA. The genes responsible for the synthesis of some of the benzoxazinoids have never been identified, and further gene expression studies are required to assess the observed correlation between the concentration of these compounds and other benzoxazinoids for which the responsible genes are known. The present study revealed a potential for breeding rye cultivars with a high content of biologically active secondary metabolites. However, growing conditions significantly influenced the level of these compounds.

Slow decomposition of lower order roots: a key mechanism of root carbon and nutrient retention in the soil.

PubMed

Fan, Pingping; Guo, Dali

2010-06-01

Among tree fine roots, the distal small-diameter lateral branches comprising first- and second-order roots lack secondary (wood) development. Therefore, these roots are expected to decompose more rapidly than higher order woody roots. But this prediction has not been tested and may not be correct. Current evidence suggests that lower order roots may decompose more slowly than higher order roots in tree species associated with ectomycorrhizal (EM) fungi because they are preferentially colonized by fungi and encased by a fungal sheath rich in chitin (a recalcitrant compound). In trees associated with arbuscular mycorrhizal (AM) fungi, lower order roots do not form fungal sheaths, but they may have poorer C quality, e.g. lower concentrations of soluble carbohydrates and higher concentrations of acid-insolubles than higher order roots, thus may decompose more slowly. In addition, litter with high concentrations of acid insolubles decomposes more slowly under higher N concentrations (such as lower order roots). Therefore, we propose that in both AM and EM trees, lower order roots decompose more slowly than higher order roots due to the combination of poor C quality and high N concentrations. To test this hypothesis, we examined decomposition of the first six root orders in Fraxinus mandshurica (an AM species) and Larix gmelinii (an EM species) using litterbag method in northeastern China. We found that lower order roots of both species decomposed more slowly than higher order roots, and this pattern appears to be associated mainly with initial C quality and N concentrations. Because these lower order roots have short life spans and thus dominate root mortality, their slow decomposition implies that a substantial fraction of the stable soil organic matter pool is derived from these lower order roots, at least in the two species we studied.

Impact of foliar herbivory on the development of a root-feeding insect and its parasitoid

PubMed Central

Bezemer, T. Martijn; Cortesero, Anne Marie; Van der Putten, Wim H.; Vet, Louise E. M.; Harvey, Jeffrey A.

2007-01-01

The majority of studies exploring interactions between above- and below-ground biota have been focused on the effects of root-associated organisms on foliar herbivorous insects. This study examined the effects of foliar herbivory by Pieris brassicae L. (Lepidoptera: Pieridae) on the performance of the root herbivore Delia radicum L. (Diptera: Anthomyiidae) and its parasitoid Trybliographa rapae (Westwood) (Hymenoptera: Figitidae), mediated through a shared host plant Brassica nigra L. (Brassicaceae). In the presence of foliar herbivory, the survival of D. radicum and T. rapae decreased significantly by more than 50%. In addition, newly emerged adults of both root herbivores and parasitoids were significantly smaller on plants that had been exposed to foliar herbivory than on control plants. To determine what factor(s) may have accounted for the observed results, we examined the effects of foliar herbivory on root quantity and quality. No significant differences in root biomass were found between plants with and without shoot herbivore damage. Moreover, concentrations of nitrogen in root tissues were also unaffected by shoot damage by P. brassicae larvae. However, higher levels of indole glucosinolates were measured in roots of plants exposed to foliar herbivory, suggesting that the development of the root herbivore and its parasitoid may be, at least partly, negatively affected by increased levels of these allelochemicals in root tissues. Our results show that foliar herbivores can affect the development not only of root-feeding insects but also their natural enemies. We argue that such indirect interactions between above- and below-ground biota may play an important role in the structuring and functioning of communities. PMID:17334787

From experiments to simulations: tracing Na+ distribution around roots under different transpiration rates and salinity levels

NASA Astrophysics Data System (ADS)

Perelman, Adi; Jorda, Helena; Vanderborght, Jan; Pohlmeier, Andreas; Lazarovitch, Naftali

2017-04-01

When salinity increases beyond a certain threshold it will result in reduced crop yield at a fixed rate, according to Maas and Hoffman model (1976). Thus, there is a great importance of predicting salinization and its impact on crops. Current models do not consider the impact of environmental conditions on plants salt tolerance, even though these conditions are affecting plant water uptake and therefore salt accumulation around the roots. Different factors, such as transpiration rates, can influence the plant sensitivity to salinity by influencing salt concentrations around the roots. Better parametrization of a model can help improving predicting the real effects of salinity on crop growth and yield. The aim of this research is to study Na+ distribution around roots at different scales using different non-invasive methods, and study how this distribution is being affected by transpiration rate and plant water uptake. Results from tomato plants growing on Rhizoslides (capillary paper growth system), show that Na+ concentration is higher at the root- substrate interface, compared with the bulk. Also, Na+ accumulation around the roots decreased under low transpiration rate, which is supporting our hypothesis. Additionally, Rhizoslides enable to study roots' growth rate and architecture under different salinity levels. Root system architecture was retrieved from photos taken during the experiment and enabled us to incorporate real root systems into a simulation. To observe the correlation of root system architectures and Na+ distribution in three dimensions, we used magnetic resonance imaging (MRI). MRI provides fine resolution of Na+ accumulation around a single root without disturbing the root system. With time, Na+ was accumulating only where roots were found in the soil and later on around specific roots. These data are being used for model calibration, which is expected to predict root water uptake in saline soils for different climatic conditions and different soil water availabilities.

Distribution of root exudates and mucilage in the rhizosphere: combining 14C imaging with neutron radiography

NASA Astrophysics Data System (ADS)

Holz, Maire; Carminati, Andrea; Kuzyakov, Yakov

2015-04-01

Water and nutrients will be the major factors limiting food production in future. Plant roots employ various mechanisms to increase the access to limited soil resources. Low molecular weight organic substances released by roots into the rhizosphere increase nutrient availability by interactions with microorganisms, while mucilage improves water availability under low moisture conditions. Though composition and quality of these substances have intensively been investigated, studies on the spatial distribution and quantification of exudates in soil are scarce. Our aim was to quantify and visualize root exudates and mucilage distribution around growing roots using neutron radiography and 14C imaging depending on drought stress. Plants were grown in rhizotrons well suited for neutron radiography and 14C imaging. Plants were exposed to various soil water contents experiencing different levels of drought stress. The water content in the rhizosphere was imaged during several drying/wetting cycles by neutron radiography. The radiographs taken a few hours after irrigation showed a wet region around the root tips showing the allocation and distribution of mucilage. The increased water content in the rhizosphere of the young root segments was related to mucilage concentrations by parameterization described in Kroener et al. (2014). In parallel 14C imaging of root after 14CO2 labeling of shoots (Pausch and Kuzyakov 2011) showed distribution of rhizodeposits including mucilage. Three days after setting the water content, plants were labeled in 14CO2 atmosphere. Two days later 14C distribution in soil was imaged by placing a phosphor-imaging plate on the rhizobox. To quantify rhizodeposition, 14C activity on the image was related to the absolute 14C activity in the soil and root after destructive sampling. By comparing the amounts of mucilage (neutron radiography) with the amount of total root derived C (14C imaging), we were able to differentiate between mucilage and root exudates. We found that mucilage and 14C concentrations were higher around the young root segments. Mucilage concentration was particularly high in the most apical 3-5 cm of the roots. Drought stress increased 14C exudation relative to C fixation and led to higher mucilage concentrations around roots. However, it remains unclear, whether the lower mucilage concentration around roots grown at higher soil moisture was caused by the faster diffusion of mucilage in wet soils. Therefore, a second experiment was focused on diffusion of mucilage in soil at varying water contents. The diffusion of mucilage in soil was not very sensitive to soil water content. We conclude that mucilage release was higher for plants exposed to drought stress. In summary, the combination of neutron radiography and 14C imaging can successfully be used to visualize and to quantify the distribution of mucilage and root exudates in the rhizosphere of plants grown in soil. References Kroener, E., Zarebanadkouki, M., Kaestner, A., & Carmintati, A. (2014). Nonequilibrium water dynamics in the rhizosphere: How mucilage affects water flow in soils. Water Resources Research, 37. Pausch, J., & Kuzyakov, Y. (2011). Photoassimilate allocation and dynamics of hotspots in roots visualized by 14C phosphor imaging. Journal of Plant Nutrition and Soil Science, 174(1), 12-19.

Variation in the concentration and age of nonstructural carbon stored in different tree tissues

NASA Astrophysics Data System (ADS)

Richardson, Andrew; Carbone, Mariah; Huggett, Brett; Furze, Morgan; Czimczik, Claudia I.; Xu, Xiaomei

2014-05-01

Trees store nonstructural carbon (NSC), in the form of sugars and starch, in the ray parenchyma cells of woody tissues. These reserves provide a carbon buffer when demand (growth, protection, or metabolism) exceeds supply (photosynthesis). This is particularly important in the context of resilience to stress and disturbance, such as might be associated with various global change factors. However, storage allocation processes and the availability of stored reserves remain poorly understood in woody plants. To better understand how NSC reserves are distributed throughout the tree, and the degree to which NSC reserves mix across ring boundaries and tissue types, we destructively sampled two 30-year-old trees (one red oak, Quercus rubra L., and one white pine, Pinus strobus L.) growing at Harvard Forest, an oak-dominated temperate forest in the northeastern United States. We analyzed stemwood samples (divided into individual rings, bark, and phloem), coarse and fine branches, and coarse (separated into three depths) and fine roots for concentrations of total sugars and starch. For a subset of samples we used the radiocarbon (14C) "bomb spike" method to estimate the mean age of extracted sugars and starch. In oak, stemwood sugar and starch concentrations were highest (50 mg/g) in the youngest (most recently-formed) rings, and dropped off rapidly (to 10 mg/g or less) across the 10 most recent rings. In oak phloem tissue, sugar concentrations were high (90 mg/g) compared to starch (10 mg/g). In pine, sugar concentrations dropped off rapidly across the three most recent rings (from 30 mg/g to 10 mg/g) whereas starch concentrations were low even for the youngest rings (10 mg/g or less). In pine, phloem concentrations of both sugar (190 mg/g) and starch (20 mg/g) were both substantially higher than in oak. Such strong radial trends must be accounted for when scaling up to whole-tree budgets, as whole increment cores cannot properly integrate (on a ring-area basis) across the depth profile. In oak, fine root concentrations of sugar and starch were similar (40 mg/g), and coarse roots had very high concentrations of starch (140 mg/g) compared to sugar (50 mg/g). In pine, fine root concentrations of both sugar and starch (60 mg/g) were higher than in coarse roots (10 mg/g). Coarse root NSC concentrations did not vary substantially along a radial gradient into the root. Even assuming a 1:5 root:shoot ratio, these data indicate that a large portion of the whole-tree NSC budget is stored belowground. For both sugars and starch, the 14C data indicated substantial mixing of new and older carbon across the youngest stemwood rings (up to 5 y), beyond which NSC age increased linearly with ring age. Coarse root NSC age also increased with radial depth and wood tissue age, and root NSC was consistently younger in pine than oak. The fact that NSC age is not constant with radial depth in the aboveground samples demonstrates that NSC reserves cannot be treated as a single, well-mixed pool. Rather, these results are consistent with previous observation suggesting last-in/first-out dynamics. From a modeling standpoint, these results support a simple two-pool structure where new photosynthate not used for current growth or metabolism enters a well-mixed and young "fast" pool, but over time storage in older rings is transferred to a distinct and older "slow" pool with which mixing no longer occurs.

Adaptive response of arbuscular mycorrhizal symbiosis to accumulation of elements and translocation in Phragmites australis affected by cadmium stress.

PubMed

Huang, Xiaochen; Ho, Shih-Hsin; Zhu, Shishu; Ma, Fang; Wu, Jieting; Yang, Jixian; Wang, Li

2017-07-15

Arbuscular mycorrhizal (AM) fungi have been reported to play a central role in improving plant tolerance to cadmium (Cd)-contaminated sites. This is achieved by enhancing both the growth of host plants and the nutritive elements in plants. This study assessed potential regulatory effects of AM symbiosis with regard to nutrient uptake and transport, and revealed different response strategies to various Cd concentrations. Phragmites australis was inoculated with Rhizophagus irregularis in the greenhouse cultivation system, where it was treated with 0-20 mg L -1 of Cd for 21days to investigate growth parameters, as well as Cd and nutritive element distribution in response to AM fungus inoculation. Mycorrhizal plants showed a higher tolerance, particularly under high Cd-level stress in the substrate. Moreover, our results determined the roots as dominant Cd reservoirs in plants. The AM fungus improved Cd accumulation and saturated concentration in the roots, thus inhibiting Cd uptake to shoots. The observed distributions of nutritive elements and the interactions among these indicated the highest microelement contribution to roots, Ca contributed maximally in leaves, and K and P contributed similarly under Cd stress. In addition, AM fungus inoculation effectively impacted Mn and P uptake and accumulation while coping with Cd toxicity. This study also demonstrated translocation factor from metal concentration (TF) could be a good parameter to evaluate different transportation strategies induced by various Cd stresses in contrast to the bioconcentration factor (BCF) and translocation factor from metal accumulation (TF'). Copyright © 2017 Elsevier Ltd. All rights reserved.

Root chemistry and soil fauna, but not soil abiotic conditions explain the effects of plant diversity on root decomposition.

PubMed

Chen, Hongmei; Oram, Natalie J; Barry, Kathryn E; Mommer, Liesje; van Ruijven, Jasper; de Kroon, Hans; Ebeling, Anne; Eisenhauer, Nico; Fischer, Christine; Gleixner, Gerd; Gessler, Arthur; González Macé, Odette; Hacker, Nina; Hildebrandt, Anke; Lange, Markus; Scherer-Lorenzen, Michael; Scheu, Stefan; Oelmann, Yvonne; Wagg, Cameron; Wilcke, Wolfgang; Wirth, Christian; Weigelt, Alexandra

2017-11-01

Plant diversity influences many ecosystem functions including root decomposition. However, due to the presence of multiple pathways via which plant diversity may affect root decomposition, our mechanistic understanding of their relationships is limited. In a grassland biodiversity experiment, we simultaneously assessed the effects of three pathways-root litter quality, soil biota, and soil abiotic conditions-on the relationships between plant diversity (in terms of species richness and the presence/absence of grasses and legumes) and root decomposition using structural equation modeling. Our final structural equation model explained 70% of the variation in root mass loss. However, different measures of plant diversity included in our model operated via different pathways to alter root mass loss. Plant species richness had a negative effect on root mass loss. This was partially due to increased Oribatida abundance, but was weakened by enhanced root potassium (K) concentration in more diverse mixtures. Equally, grass presence negatively affected root mass loss. This effect of grasses was mostly mediated via increased root lignin concentration and supported via increased Oribatida abundance and decreased root K concentration. In contrast, legume presence showed a net positive effect on root mass loss via decreased root lignin concentration and increased root magnesium concentration, both of which led to enhanced root mass loss. Overall, the different measures of plant diversity had contrasting effects on root decomposition. Furthermore, we found that root chemistry and soil biota but not root morphology or soil abiotic conditions mediated these effects of plant diversity on root decomposition.

Selected natural and fallout radionuclides in plant foods around the Kudankulam Nuclear Power Project, India.

PubMed

Ross, E Mahiban; Raj, Y Lenin; Wesley, S Godwin; Rajan, M P

2013-01-01

The activity concentrations of certain radionuclides were quantified in some plant foods cultivated around Kudankulam, where a mega-nuclear power plant is being established. The activity concentrations were found more in the 'pulses' group and were the lowest in 'other vegetable' category. The annual effective dose was computed based on the activity concentration of radionuclides and it was found to be higher due to the consumption of cereals and pulses. Other vegetables, cereals, pulses and nuts recorded high transfer factors for the radionuclide (228)Ra. Fruits, leafy vegetables, tubers and roots, and palm embryo registered high transfer factors for (226)Ra. Group-wise activity concentration, radiation dose to the public and soil-plant-to-transfer factor are discussed in detail. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effectiveness of arbuscular mycorrhizal fungi in phytoremediation of lead- contaminated soil by vetiver grass.

PubMed

Bahraminia, Mahboobeh; Zarei, Mehdi; Ronaghi, Abdolmajid; Ghasemi-Fasaei, Reza

2016-01-01

A greenhouse experiment was conducted to evaluate the effectiveness of arbuscular mycorrhizal (AM) fungi in phytoremediation of lead (Pb)-contaminated soil by vetiver grass. Experiment was a factorial arranged in a completely randomized design. Factors included four Pb levels (50, 200, 400, and 800 mg kg(-1)) as Pb (NO3)2, AM fungi at three levels (non mycorrhizal (NM) control, Rhizophagus intraradices, Glomus versiforme). Shoot and root dry weights (SDW and RDW) decreased as Pb levels increased. Mycorrhizal inoculation increased SDW and RDW compared to NM control. With mycorrhizal inoculation and increasing Pb levels, Pb uptake of shoot and root increased compared to those of NM control. Root colonization increased with mycorrhizal inoculation but decreased as Pb levels increased. Phosphorus concentration and uptake in shoot of plants inoculated with AM fungi was significantly higher than NM control at 200 and 800 mg Pb kg(-1). The Fe concentration, Fe and Mn uptake of shoot in plants inoculated with Rhizophagus intraradices in all levels of Pb were significantly higher than NM control. Mycorrhizal inoculation increased Pb extraction, uptake and translocation efficiencies. Lead translocation factor decreased as Pb levels increased; however inoculation with AM fungi increased Pb translocation.

Phytoextraction of HG by parsley (Petroselinum crispum) and its growth responses.

PubMed

Bibi, Asma; Farooq, Umar; Naz, Sadia; Khan, Afsar; Khan, Sara; Sarwar, Rizwana; Mahmood, Qaisar; Alam, Arif; Mirza, Nosheen

2016-01-01

The effect of mercury (Hg) on the growth and survival of parsley (Petroselinum crispum) was explored at various treatments. The plants were grown in pots having Hoagland's solution to which various Hg treatments were applied and placed under greenhouse conditions. The treatments were: no metal applied (control) and six doses of Hg as mercuric chloride for 15 days. Linear trend of Hg accumulation was noted in roots, stems, and leaves with increasing Hg treatments. The maximum Hg concentration in root, stem and leaf was 8.92, 8.27, and 7.88 at Hg treatments of 25 mg l(-1), respectively. On the whole, Hg accumulation in different plant parts was in the following order: leaves > stem > roots. Linear trend was also observed for Bioaccumulation Factor (BF) and Translocation Factor (TF) with increasing Hg concentrations in the growth medium. The highest respective BFHg and TFHg values were 9.32 and 2.02 for the Hg treatments of 25 and 50 mg l(-1). In spite of the reduced growth in the presence of Hg, the plant has phytoremediation potential. It is recommended that parsley should not be cultivated in Hg contaminated sites in order to avoid dietary toxicity.

Estimation of runoff mitigation by morphologically different cover crop root systems

NASA Astrophysics Data System (ADS)

Yu, Yang; Loiskandl, Willibald; Kaul, Hans-Peter; Himmelbauer, Margarita; Wei, Wei; Chen, Liding; Bodner, Gernot

2016-07-01

Hydrology is a major driver of biogeochemical processes underlying the distinct productivity of different biomes, including agricultural plantations. Understanding factors governing water fluxes in soil is therefore a key target for hydrological management. Our aim was to investigate changes in soil hydraulic conductivity driven by morphologically different root systems of cover crops and their impact on surface runoff. Root systems of twelve cover crop species were characterized and the corresponding hydraulic conductivity was measured by tension infiltrometry. Relations of root traits to Gardner's hydraulic conductivity function were determined and the impact on surface runoff was estimated using HYDRUS 2D. The species differed in both rooting density and root axes thickness, with legumes distinguished by coarser axes. Soil hydraulic conductivity was changed particularly in the plant row where roots are concentrated. Specific root length and median root radius were the best predictors for hydraulic conductivity changes. For an intensive rainfall simulation scenario up to 17% less rainfall was lost by surface runoff in case of the coarsely rooted legumes Melilotus officinalis and Lathyrus sativus, and the densely rooted Linum usitatissimum. Cover crops with coarse root axes and high rooting density enhance soil hydraulic conductivity and effectively reduce surface runoff. An appropriate functional root description can contribute to targeted cover crop selection for efficient runoff mitigation.

Water flow and solute transport in the soil-plant-atmosphere continuum: Upscaling from rhizosphere to root zone

NASA Astrophysics Data System (ADS)

Lazarovitch, Naftali; Perelman, Adi; Guerra, Helena; Vanderborght, Jan; Pohlmeier, Andreas

2016-04-01

Root water and nutrient uptake are among the most important processes considered in numerical models simulating water content and fluxes in the subsurface, as they control plant growth and production as well as water flow and nutrient transport out of the root zone. Root water uptake may lead to salt accumulation at the root-soil interface, resulting in rhizophere salt concentrations much higher than in the bulk soil. This salt accumulation is caused by soluble salt transport towards the roots by mass flow through the soil, followed by preferential adsorption of specific nutrients by active uptake, thereby excluding most other salts at the root-soil interface or in the root apoplast. The salinity buildup can lead to large osmotic pressure gradients across the roots thereby effectively reducing root water uptake. The initial results from rhizoslides (capillary paper growth system) show that sodium concentration is decreasing with distance from the root, compared with the bulk that remained more stable. When transpiration rate was decreased under high salinity levels, sodium concentration was more homogenous compared with low salinity levels. Additionally, sodium and gadolinium distributions were measured nondestructively around tomato roots using magnetic resonance imaging (MRI). This technique could also observe the root structure and water content around single roots. Results from the MRI confirm the solutes concentration pattern around roots and its relation to their initial concentration. We conclude that local water potentials at the soil-root interface differ from bulk potentials. These relative differences increase with decreasing root density, decreasing initial salt concentration and increasing transpiration rate. Furthermore, since climate may significantly influence plant response to salinity a dynamic climate-coupled salinity reduction functions are critical in while using macroscopic numerical models.

Evaluation of the cadmium and lead phytoextraction by castor bean (Ricinus communis L.) in hydroponics

NASA Astrophysics Data System (ADS)

Niu, Z. X.; Sun, L. N.

2017-06-01

Phytoextraction has been considered as an innovative method to remove toxic metals from soil; higher biomass plants such as castor bean (Ricinus communis L.) have already been considered as a hyperaccumulating candidate. In the present study, castor bean was used to accumulate the cadmium and lead in hydroponic culture, and the root exudates and biomass changes were analyzed. Results demonstrated that ratios of aerial biomass/ root biomass (AW/RW) in treatments declined with concentrations of Cd or Pb. Optical density (OD) at 190 nm and 280 nm of root exudates observed in Cd and Pb treatments were lower than the control. In single Cd or Pb treatments, bioconcentration factors (BCF) of Cd or Pb increased with time and decreased with concentrations, the highest BCFs appeared in Cd5 (14.36) and Pb50 (6.48), respectively. Cd-BCF or Pb-BCF showed positive correlations with AW/RW ratios and OD values, and they were negative correlated with Cd and Pb concentration. Results in this study may supply useful information for phytoremediation of soil contaminated with cadmium and lead in situ.

A study on possible use of Urtica dioica (common nettle) plant as polonium (210)Po and lead (210)Pb contamination biomonitor in the area of phosphogypsum stockpile.

PubMed

Olszewski, Grzegorz; Boryło, Alicja; Skwarzec, Bogdan

2016-04-01

The aim of this study was to test a possible use of Urtica dioica (common nettle) plant as a biomonitor of polonium (210)Po and lead (210)Pb contamination near phosphogypsum stacks by determining concentrations of these radionuclides in samples collected from the area of phosphogypsum stockpile in Wiślinka (northern Poland). The (210)Po and (210)Pb contents in roots depended on their concentrations in soils. Bioconcentration factor values from soil to root of the plant did not depend on (210)Po and (210)Pb contents in soils that leads to the conclusion that different polonium and lead species have different affinities to U. dioica plants. The main sources of both analyzed radionuclides in green parts of plants are wet and dry air deposition and transportation from soil. The values of (210)Po/(210)Pb activity ratio indicate natural origin of these radioisotopes in analyzed plants. (210)Po and (210)Pb concentration in U. dioica roots is negatively weakly correlated with distance from phosphogypsum stockpile.

Characterization of Cd translocation and accumulation in 19 maize cultivars grown on Cd-contaminated soil: implication of maize cultivar selection for minimal risk to human health and for phytoremediation.

PubMed

Wang, Aiyun; Wang, Minyan; Liao, Qi; He, Xiquan

2016-03-01

Maize (Zea mays) has low Cd accumulation in grains and a high biomass compared to other crops. The capacities for Cd accumulation in different maize cultivars are, however, not fully understood. To reduce human health risk from maize grown in Cd-contaminated soil and to provide promising maize cultivars for the phytoremediation of Cd-polluted soil, a field experiment was conducted to screen low-Cd- and high-Cd-accumulation maize cultivars by evaluating the yield, Cd uptake, translocation, and accumulation differences among 19 maize cultivars. There were differences in straw dry weight (DW), root DW, and yield among the 19 cultivars. The cultivars Yudan19, Zhengda999, and Xianyu508 had a higher production compared to that of the other cultivars. The Cd concentrations in the roots were much higher than those in the straws and grains in all cultivars. The Cd accumulation factors (AFS) decreased in the order of accumulation factors in root (AFrs) > accumulation factors in straw (AFss) > accumulation factors in grain (AFgs). The Cd translocation factors (TFs) from root to straw (TFrs) were significantly (p < 0.05) larger than those from straw to grain (TFsg) among all of the cultivars. The TFs for all of the cultivars was less than 1, and the lowest TFsg (0.23) was found in cultivar Xiangyongdan3. The correlation analysis indicated that Cd concentrations in straws showed a significant (p < 0.01) as well as positive correlation with TFrs while a negative correlation with TFsg (p < 0.01). Moreover, Cd accumulation in different tissues decreased in the order straw > grain > root. Among the 19 maize cultivars, Jixiang2118 and Kangnong18 accumulated the highest Cd amount in the aboveground tissues, and the corresponding values were 7,206.51 and 6,598.68 mg hm(-2), respectively. A hierarchical cluster analysis based on the Cd concentrations in grains and straws classified the 19 maize cultivars into four and two groups for a 0.4 minimum distance between clusters, respectively. Yudan19, Zhengda999, and Xianyu508 can be classified into one group in which low Cd in grains meeting the Cd tolerance limit in foods set by China National Standard, suggesting that those cultivars are safety for food and human health. However, Jixiang2118 and Kangnong18 can be classified as another group with potential application for phytoremediation in slightly or moderately Cd-polluted soil because of the high Cd accumulation in the aboveground tissues.

Cadmium accumulation and tolerance of Lagerstroemia indica and Lagerstroemia fauriei (Lythraceae) seedlings for phytoremediation applications.

PubMed

Wang, Yixiang; Gu, Cuihua; Bai, Shangbin; Sun, Zhibin; Zhu, Tingting; Zhu, Xudan; Grit, Dale H; Tembrock, Luke R

2016-11-01

Contamination by heavy metals is one of the most serious environmental problems generated from human activities. Because phytoremediation utilizes plants to uptake contaminants, it could potentially be used to remediate metal-contaminated areas. A pot culture experiment with four levels of cadmium (Cd) (0, 20, 40, and 80 mg of Cd/kg dry soil) was conducted to investigate Cd accumulation and tolerance of roots, shoots, and leaves of Lagerstroemia indica and Lagerstroemia fauriei as well as their potential for phytoremediation. Experimental results indicated that Cd inhibited seedling growth only at the higher Cd exposure concentration (40 and 80 mg/kg). The tolerance index revealed that on average L. indica is more tolerant of Cd than L. fauriei. Moreover, plants in the experiment accumulated Cd differentially. In comparisons between L. indica and L. fauriei, the leaves of the former had higher concentrations of Cd, while the roots of latter had higher concentrations of Cd. Furthermore, the roots, shoots, and leaves had very high bioaccumulation factors that markedly exceeded 1.0 (exceptional only in shoots of 80 mg/kg for L. fauriei), indicating that the seedlings extracted Cd from the soil. The leaves' translocation factor of L. indica was greater than 1.0, being significantly higher than that of L. fauriei. Chlorophyll a, Chlorophyll b and total declined in both species significantly as Cd concentrations exceeded 40 mg/kg in the soil. In contrast, lipid peroxidation and proline content was found to increase with increasing Cd concentration. From the assessments of biomass production, Cd tolerance and uptake L. indica and L. fauriei could stand as excellent species for remediating Cd-contaminated soils.

Hyperaccumulation of zinc by Corydalis davidii in Zn-polluted soils.

PubMed

Lin, Wenjie; Xiao, Tangfu; Wu, Yunying; Ao, Ziqiang; Ning, Zengping

2012-02-01

A field survey was conducted to identify potential Zn accumulators from an artisanal Zn smelting area in southwest China's Guizhou Province. Hydroponic and soil culture experiments were performed to investigate the accumulation ability of Zn in Corydalis davidii. Zn concentrations in roots, stems and leaves of C. davidii in the smelting site were 1.1-3.5, 1.2-11.2, and 3.3-14 mg g(-)(1), respectively, whereas Zn concentrations in roots, stems and leaves of C. davidii in the contaminated site impacted by the Zn smelting were 1.0-2.4, 1.9-6.5, and 3.0-1.1 mg g(-1), respectively. Zn concentrations in leaves and stems of C. davidii were observed at above 10 mg g(-1) that refers to the threshold of Zn hyperaccumulator. The concentration distribution of Zn in C. davidii was leaf>stem>root, and the Zn bioaccumulation factors of C. davidii were above 1. It is concluded that C. davidii has high tolerance to concentrate Zn stress, and that C. davidii is a newly discovered Zn-hyperaccumulator with high biomass in the aboveground parts. Based on the cultivation experiments, C. davidii could reduce Zn concentration by 26.6, 21.2, and 10.2 mg kg(-1)yr(-1) by phytoextraction from the smelting slag, Zn-contaminated soil, and background soil, respectively. Copyright © 2011 Elsevier Ltd. All rights reserved.

Up-Regulation of a Magnesium Transporter Gene OsMGT1 Is Required for Conferring Aluminum Tolerance in Rice1[W][OA

PubMed Central

Chen, Zhi Chang; Yamaji, Naoki; Motoyama, Ritsuko; Nagamura, Yoshiaki; Ma, Jian Feng

2012-01-01

Magnesium (Mg)-mediated alleviation of aluminum (Al) toxicity has been observed in a number of plant species, but the mechanisms underlying the alleviation are still poorly understood. When a putative rice (Oryza sativa) Mg transporter gene, Oryza sativa MAGNESIUM TRANSPORTER1 (OsMGT1), was knocked out, the tolerance to Al, but not to cadmium and lanthanum, was decreased. However, this inhibition could be rescued by addition of 10 μm Mg, but not by the same concentration of barium or strontium. OsMGT1 was expressed in both the roots and shoots in the absence of Al, but the expression only in the roots was rapidly up-regulated by Al. Furthermore, the expression did not respond to low pH and other metals including cadmium and lanthanum, and was regulated by an Al-responsive transcription factor, AL RESISTANCE TRANSCRIPTION FACTOR1. An investigation of subcellular localization showed that OsMGT1 was localized to the plasma membrane. A short-term (30 min) uptake experiment with stable isotope 25Mg showed that knockout of OsMGT1 resulted in decreased Mg uptake, but that the uptake in the wild type was enhanced by Al. Mg concentration in the cell sap of the root tips was also increased in the wild-type rice, but not in the knockout lines in the presence of Al. A microarray analysis showed that transcripts of genes related to stress were more up- and down-regulated in the knockout lines. Taken together, our results indicate that OsMGT1 is a transporter for Mg uptake in the roots and that up-regulation of this gene is required for conferring Al tolerance in rice by increasing Mg concentration in the cell. PMID:22732245

Effectiveness of remediation of metal-contaminated mangrove sediments (Sydney estuary, Australia).

PubMed

Birch, Gavin; Nath, Bibhash; Chaudhuri, Punarbasu

2015-04-01

Industrial activities and urbanization have had a major consequence for estuarine ecosystem health and water quality globally. Likewise, Sydney estuary has been significantly impacted by widespread, poor industrial practices in the past, and remediation of legacy contaminants have been undertaken in limited parts of this waterway. The objective of the present investigation was to determine the effectiveness of remediation of a former Pb-contaminated industrial site in Homebush Bay on Sydney estuary (Australia) through sampling of inter-tidal sediments and mangrove (Avicennia marina) tissue (fine nutritive roots, pneumatophores, and leaves). Results indicate that since remediation 6 years previously, Pb and other metals (Cu, Ni and Zn) in surficial sediment have increased to concentrations that approach pre-remediation levels and that they were considerably higher than pre-settlement levels (3-30 times), as well as at the reference site. Most metals were compartmentalized in fine nutritive roots with bio-concentration factors greater than unity, while tissues of pneumatophores and leaves contained low metal concentrations. Lead concentrations in fine nutritive root, pneumatophore, and leaf tissue of mangroves from the remediated site were similar to trees in un-remediated sites of the estuary and were substantially higher than plants at the reference site. The situation for Zn in fine nutritive root tissue was similar. The source of the metals was either surface/subsurface water from the catchment or more likely remobilized contaminated sediment from un-remediated parts of Homebush Bay. Results of this study demonstrate the problems facing management in attempting to reduce contamination in small parts of a large impacted area to concentrations below local base level.

Physiological and growth responses of Centaurea maculosa (Asteraceae) to root herbivory under varying levels of interspecific plant competition and soil nitrogen availability.

PubMed

Steinger, Thomas; Müller-Schärer, Heinz

1992-08-01

Centaurea maculosa seedlings were grown in pots to study the effects of root herbivory by Agapeta zoegana L. (Lep.: Cochylidae) and Cyphocleonus achates Fahr. (Col.: Curculionidae), grass competition and nitrogen shortage (each present or absent), using a full factorial design. The aims of the study were to analyse the impact of root herbivory on plant growth, resource allocation and physiological processes, and to test if these plant responses to herbivory were influenced by plant competition and nitrogen availability. The two root herbivores differed markedly in their impact on plant growth. While feeding by the moth A. zoegana in the root cortex had no effect on shoot and root mass, feeding by the weevil C. achates in the central vascular tissue greatly reduced shoot mass, but not root mass, leading to a reduced shoot/root ratio. The absence of significant effects of the two herbivores on root biomass, despite considerable consumption, indicates that compensatory root growth occurred. Competition with grass affected plant growth more than herbivory and nutrient status, resulting in reduced shoot and root growth, and number of leaves. Nitrogen shortage did not affect plant growth directly but greatly influenced the compensatory capacity of Centaurea maculosa to root herbivory. Under high nitrogen conditions, shoot biomass of plants infested by the weevil was reduced by 30% compared with uninfested plants. However, under poor nitrogen conditions a 63% reduction was observed compared with corresponding controls. Root herbivory was the most important stress factor affecting plant physiology. Besides a relative increase in biomass allocation to the roots, infested plants also showed a significant increase in nitrogen concentration in the roots and a concomitant reduction in leaf nitrogen concentration, reflecting a redirection of the nitrogen to the stronger sink. The level of fructans was greatly reduced in the roots after herbivore feeding. This is thought to be a consequence of their mobilisation to support compensatory root growth. A preliminary model linking the effects of these root herbivores to the physiological processes of C. maculosa is presented.

Effects of environmental biomass-producing factors on Cd uptake in two Swedish ecotypes of Pinus sylvestris.

PubMed

Ekvall, Lars; Greger, Maria

2003-01-01

A factorial design was used to study direct effects of external biomass-producing factors such as light, temperature and photoperiod on cadmium (Cd) uptake and indirect effects, via change in biomass production in two ecotypes of Scots pine (Pinus silvestris). The aim was to find out if the external factors affect the Cd uptake directly or via change in biomass production, and if the effect differs between ecotypes. Seedlings were grown under 10 combinations of external factors, i.e. temperature (15 and 20 degrees C), light intensity (50 and 200 micromol photons m(-2) S(-1)), photoperiod (18 h light/8 h darkness and continuous light) and external Cd concentration (totally 1.88 and 7.50 micromol). The treatment lasted for 18 days and Cd concentrations in roots and shoots were determined by AAS. The results showed that an increased biomass production increased the total Cd uptake but had a dilution effect on the Cd concentration, especially in the root tissues. The external factors tested did not have any direct effects on the Cd untake, only in the case of Cd translocation to the shoot did the higher temperature show a direct increase, but only in the southern ecotype. The two ecotypes reacted differently in Cd uptake and translocation to the external factors studied. The relative Cd uptake creased with increasing photoperiod in the northern but not in the southern ecotype. The southern ecotype decreased the Cd concentration in the shoot with increased light intensity caused by a dilution effect due to extensive shoot growth of this ecotype. The conclusion is that the uptake in pine seedlings is mainly regulated via biomass production, and not directly by light and temperature and that resulting plant Cd contents to a certain extent depend on plant origin.

UV-B Induced Generation of Reactive Oxygen Species Promotes Formation of BFA-Induced Compartments in Cells of Arabidopsis Root Apices

PubMed Central

Yokawa, Ken; Kagenishi, Tomoko; Baluška, František

2016-01-01

UV-B radiation is an important part of the electromagnetic spectrum emitted by the sun. For much of the period of biological evolution organisms have been exposed to UV radiation, and have developed diverse mechanisms to cope with this potential stress factor. Roots are usually shielded from exposure to UV by the surrounding soil, but may nevertheless be exposed to high energy radiation on the soil surface. Due to their high sensitivity to UV-B radiation, plant roots need to respond rapidly in order to minimize exposure on the surface. In addition to root gravitropism, effective light perception by roots has recently been discovered to be essential for triggering negative root phototropism in Arabidopsis. However, it is not fully understood how UV-B affects root growth and phototropism. Here, we report that UV-B induces rapid generation of reactive oxygen species which in turn promotes the formation of BFA-induced compartments in the Arabidopsis root apex. During unilateral UV-B irradiation of roots changes in auxin concentration on the illuminated side have been recorded. In conclusion, UV-B-induced and ROS-mediated stimulation of vesicle recycling promotes root growth and induces negative phototropism. PMID:26793199

Localized application of soil organic matter shifts distribution of cluster roots of white lupin in the soil profile due to localized release of phosphorus

PubMed Central

Li, Hai-Gang; Shen, Jian-Bo; Zhang, Fu-Suo; Lambers, Hans

2010-01-01

Background and Aims Phosphorus (P) is a major factor controlling cluster-root formation. Cluster-root proliferation tends to concentrate in organic matter (OM)-rich surface-soil layers, but the nature of this response of cluster-root formation to OM is not clear. Cluster-root proliferation in response to localized application of OM was characterized in Lupinus albus (white lupin) grown in stratified soil columns to test if the stimulating effect of OM on cluster-root formation was due to (a) P release from breakdown of OM; (b) a decrease in soil density; or (c) effects of micro-organisms other than releasing P from OM. Methods Lupin plants were grown in three-layer stratified soil columns where P was applied at 0 or 330 mg P kg−1 to create a P-deficient or P-sufficient background, and OM, phytate mixed with OM, or perlite was applied to the top or middle layers with or without sterilization. Key Results Non-sterile OM stimulated cluster-root proliferation and root length, and this effect became greater when phytate was supplied in the presence of OM. Both sterile OM and perlite significantly decreased cluster-root formation in the localized layers. The OM position did not change the proportion of total cluster roots to total roots in dry biomass among no-P treatments, but more cluster roots were concentrated in the OM layers with a decreased proportion in other places. Conclusions Localized application of non-sterile OM or phytate plus OM stimulated cluster-root proliferation of L. albus in the localized layers. This effect is predominantly accounted for by P release from breakdown of OM or phytate, but not due to a change in soil density associated with OM. No evidence was found for effects of micro-organisms in OM other than those responsible for P release. PMID:20150198

Measurement carbon dioxide concentration does not affect root respiration of nine tree species in the field

Treesearch

Andrew J. Burton; Kurt S. Pregitzer

2002-01-01

Inhibition of respiration has been reported as a short-term response of tree roots to elevated measurement CO2 concentration ([CO2]), calling into question the validity of root respiration rates determined at CO2 concentrations that differ from the soil [CO2] in the rooting zone...

Contrasting effects of nicotianamine synthase knockdown on zinc and nickel tolerance and accumulation in the zinc/cadmium hyperaccumulator Arabidopsis halleri.

PubMed

Cornu, Jean-Yves; Deinlein, Ulrich; Höreth, Stephan; Braun, Manuel; Schmidt, Holger; Weber, Michael; Persson, Daniel P; Husted, Søren; Schjoerring, Jan K; Clemens, Stephan

2015-04-01

Elevated nicotianamine synthesis in roots of Arabidopsis halleri has been established as a zinc (Zn) hyperaccumulation factor. The main objective of this study was to elucidate the mechanism of nicotianamine-dependent root-to-shoot translocation of metals. Metal tolerance and accumulation in wild-type (WT) and AhNAS2-RNA interference (RNAi) plants were analysed. Xylem exudates were subjected to speciation analysis and metabolite profiling. Suppression of root nicotianamine synthesis had no effect on Zn and cadmium (Cd) tolerance but rendered plants nickel (Ni)-hypersensitive. It also led to a reduction of Zn root-to-shoot translocation, yet had the opposite effect on Ni mobility, even though both metals form coordination complexes of similar stability with nicotianamine. Xylem Zn concentrations were positively, yet nonstoichiometrically, correlated with nicotianamine concentrations. Two fractions containing Zn coordination complexes were detected in WT xylem. One of them was strongly reduced in AhNAS2-suppressed plants and coeluted with (67) Zn-labelled organic acid complexes. Organic acid concentrations were not responsive to nicotianamine concentrations and sufficiently high to account for complexing the coordinated Zn. We propose a key role for nicotianamine in controlling the efficiency of Zn xylem loading and thereby the formation of Zn coordination complexes with organic acids, which are the main Zn ligands in the xylem but are not rate-limiting for Zn translocation. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

A new insight into root responses to external cues: Paradigm shift in nutrient sensing

PubMed Central

Bhardwaj, Deepak; Medici, Anna; Gojon, Alain; Lacombe, Benoît; Tuteja, Narendra

2015-01-01

Higher plants are sessile and their growth relies on nutrients present in the soil. The acquisition of nutrients is challenging for plants. Phosphate and nitrate sensing and signaling cascades play significant role during adverse conditions of nutrient unavailability. Therefore, it is important to dissect the mechanism by which plant roots acquire nutrients from the soil. Root system architecture (RSA) exhibits extensive developmental flexibility and changes during nutrient stress conditions. Growth of root system in response to external concentration of nutrients is a joint operation of sensor or receptor proteins along with several other cytoplasmic accessory proteins. After nutrient sensing, sensor proteins start the cellular relay involving transcription factors, kinases, ubiquitin ligases and miRNA. The complexity of nutrient sensing is still nebulous and many new players need to be better studied. This review presents a survey of recent paradigm shift in the advancements in nutrient sensing in relation to plant roots. PMID:26146897

Tracking aquaculture-derived fluoroquinolones in a mangrove wetland, South China.

PubMed

Liu, Xiao; Liu, Yu; Xu, Jian-Rong; Ren, Ke-Jun; Meng, Xiang-Zhou

2016-12-01

Aquaculture in mangrove wetlands has been developed rapidly, causing various environmental problems (e.g., antibiotic residue). In the present study, the levels and distributions of a well-known class of antibiotics (fluoroquinolones; FQs), including norfloxacin (NOR), ciprofloxacin (CIP), and enrofloxacin (ENR), were examined in sediment and mangrove plant (Aegiceras corniculatum) from a mangrove wetland in the Zhanjiang Mangrove National Nature Reserve, South China. NOR and CIP were detected in all sediment samples, with concentrations ranging from 4.3 to 64.2 ng/g and from 7.62 to 68.5 ng/g on a basis of dry weight (dw), respectively, whereas ENR was found with relatively lower frequency (<78%) and lower concentrations (<19.3 ng/g). Sediments in mangrove rhizosphere area contained considerably higher concentrations of all FQs (except for ENR). FQs were largely varied in mangrove plant tissues; NOR and ENR were not detected in leaf and root samples, respectively. CIP featured an increasing tendency from the root to the upper parts of plants, whereas a decreasing trend was found for NOR. Three bioconcentration factors (BCF s ) of FQs, including BCFs for roots (BCF r ), branches (BCF b ), and leaves (BCF l ) were calculated, and most of them exceeded 1. Especially for NOR, its BCF r can reach up to 9.9, indicating that Aegiceras corniculatum has a strong ability to accumulate FQs from sediment and/or surrounding environment. For NOR and CIP, strong positive relationships were observed between BCF r and concentrations in root, but no significant correlations were observed between BCF r and root lipid of mangrove plant. More studies are needed to investigate the uptake mechanism of antibiotics in mangrove plants. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Phytoremediation of mercury and cadmium polluted wetland by Arundo donax].

PubMed

Han, Zhiping; Hu, Xiaobin; Hu, Zhenghai

2005-05-01

With a pot culture of simulated mercury (Hg) and cadmium (Cd)-polluted wetland, this paper studied the capability of Arundo donax in accumulating these heavy metals, and their distribution in the plant. The results showed that after grown in a 101 mg.kg(-1) Hg-polluted wetland for 8 months, the Hg-concentrating capability of Arundo donax was in order of root > stem > leaf, and the Hg concentration in its aboveground parts was 200 +/- 20 mg.kg(-1) (DW); while in the case of 115 mg.kg(-1) Cd-pollution, the Cd-concentrating capability was in order of leaf > root > stem, and the Cd concentration in leaf was 160 +/- 26 mg.kg(-1) (DW). The heavy metals concentration in Arundo donax organs increased with its growth time, being 30%-50% higher for 8 months than for 4 months. The BCF (Bio-concentration factor) decreased with increasing heavy metals concentration. In polluted wetland, the BCFs of Hg by the leaf and stem were 1.9 and 2.1, and those of Cd were 1.5 and 0.3, respectively; while in unpolluted wetland, the concentration of Hg and Cd was 6.8 and 8.5 mg.kg(-1), the BCFs of Hg by the leaf and stem were 6.8 and 12.2, and those of Cd were 7.0 and 2.7, respectively. It was indicated that Arundo donax not only had the characters of large biomass, exuberant root, and good adaptability, but also exhibited high tolerance and concentrating capability to Cd and Hg.

Soil and plant contamination by lead mining in Bellmunt (Western Mediterranean Area)

NASA Astrophysics Data System (ADS)

Bech, Jaume; Duran, Paola; Barceló, Juan; Roca, Núria; Tume, Pedro; Poschenrieder, Charlotte

2010-05-01

Galena has been mined in Bellmunt (Priorat, Western Mediterranean Area) since ancient times until 1972. While sediment pollution originated by the mining activity in the Ebro river passing the region has been investigated (Ferré, 2007), the local impact on soils and plants has received little attention. Here we report the first results on the concentrations of major metal contaminants and antimony in soils and representative plants from 5 selected sites with different pollutant burdens around the mining area. Both total (HNO3, HF, HClO4 digest) and extractable (EDTA) soil concentrations were studied. The range of total and extractable soil values in mgkg-1 is as follows: Sb 9.7-31 and 2.4-7.2; Cu: 89-823 and 20-62; Pb: 19-39 and 18-33; Zn: 318-989 and 79-287 mg•kg-1, respectively). Soils had alkaline pH (7.7-8.2), organic matter contents ranging from 0.8 to 2.4%, and a sandy-loam or a loamy-sand texture. All analysed plant species showed enhanced root and shoot concentrations of Pb, Cu, Zn and Sb when growing on the more polluted soils, and all but one restricted the translocation of metals from roots to shoots exhibiting shoot/root concentration ratios lower than unity. A notably exception was Moricandia moricandioides. This species of the Brassicaceae family exhibited higher Zn concentrations in the shoots than in the roots at all sampling sites yielding shoot/root concentration ratios up to 5.5. This metal accumulation pattern was only observed for Zn and not for other analysed metal contaminants. The concentrations of other, poorly mobile metals, like Pb or Cu were always higher in roots than in shoots (e.g. Pb shoot/root ratios ranged from 0.12 to 0.41). Taking into account the high Pb burden of the soil samples and these low shoot/root Pb ratios, it can be excluded that the particular Zn accumulation pattern of Moricandia moricandioides was biased by soil contamination of shoot samples. To the best of our knowledge, this is the first report of a Zn accumulation behaviour in a Moricandia species. The soil-to-shoot transfer factors (shoot Zn conc/total soil conc.) for this species were, however, relatively low ranging from 0.3 to 1.3. Two main reasons for this could be 1) the fact that real total Zn soil concentrations after HF attack and not pseudototal metal concentrations were analysed in the present study and 2) the relatively high pH of the soils which could considerably hamper Zn bioavailability. Further studies are required to confirm the possible Zn (hyper)accumulator character of Moricandia moricandioides (Boiss.) Heyw. [M. ramburii Webb]. Reference: Ferré, N. 2007 Nivells de metals pesants a la conca Catalana del riu Ebre. Avaluació del risc per la población i l'ecosistema. Universitat Rovira Virgili. ISBN 978-84-691-0371-5. Acknowledgement: Supported by BFU2007-60332/BFI

[C, N and P stoichiometric characteristics of different root orders for three dominant tree species in subalpine forests of western Sichuan, China].

PubMed

Tang, Shi-shan; Yang, Wan-qin; Xiong, Li; Yin, Rui; Wang, Hai-peng; Zhang, Yan; Xu, Zhen-feng

2015-02-01

Fine root order was classified according to Pregitzer's method. This study measured carbon (C), nitrogen (N) and phosphorus (P) concentrations of the 1-5 root orders (diameter < 2 mm) in three dominant subalpine tree species (Betula albosinensis, Abies faxoniana and Picea asperata) of western Sichuan. Their stoichiometric ratios of different root orders were also calculated. The results showed that C concentration, C/N and C/P increased, but N and P concentrations decreased from the first to fifth order of fine root for all tree species. No significant changes in N/P among root orders were detected in each species. There were significant differences in C, N, P concentrations and their stoichiometric ratios among the tree species. The species-associated differences were dependent on root order. There were significant correlations between C, N, P concentrations and their stoichiometric ratios in the three tree species.

Quantitative mapping of solute accumulation in a soil-root system by magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Haber-Pohlmeier, S.; Vanderborght, J.; Pohlmeier, A.

2017-08-01

Differential uptake of water and solutes by plant roots generates heterogeneous concentration distributions in soils. Noninvasive observations of root system architecture and concentration patterns therefore provide information about root water and solute uptake. We present the application of magnetic resonance imaging (MRI) to image and monitor root architecture and the distribution of a tracer, GdDTPA2- (Gadolinium-diethylenetriaminepentacetate) noninvasively during an infiltration experiment in a soil column planted with white lupin. We show that inversion recovery preparation within the MRI imaging sequence can quantitatively map concentrations of a tracer in a complex root-soil system. Instead of a simple T1 weighting, the procedure is extended by a wide range of inversion times to precisely map T1 and subsequently to cover a much broader concentration range of the solute. The derived concentrations patterns were consistent with mass balances and showed that the GdDTPA2- tracer represents a solute that is excluded by roots. Monitoring and imaging the accumulation of the tracer in the root zone therefore offers the potential to determine where and by which roots water is taken up.

Assessment of plant-driven uptake and translocation of clofibric acid by Scirpus validus.

PubMed

Zhang, Dong Qing; Gersberg, Richard M; Hua, Tao; Zhu, Junfei; Ng, Wun Jern; Tan, Soon Keat

2013-07-01

Pharmaceutical compounds are now considered as emerging contaminants of environmental concern. The overall objective of this study was to evaluate the uptake and translocation of clofibric acid (CA) by the macrophyte Scirpus validus growing hydroponically. A set of the three replicates was established for each exposure time and for each CA concentration. Plants were grown in 4 L vessels (four plants per vessel corresponding to the three exposure period studies, i.e., 7, 14, 18, and 21 days) which contained an aerated modified Hoagland nutrient solution that was spiked with CA at concentrations of 0.5, 1.0, and 2.0 mg L(-1). At each exposure period, CA concentration was measured in the nutrient solutions. A sea sand disruption method was employed for the extraction of CA from plant tissues. The determination of the pharmaceutical concentration was carried out using solid phase extraction (SPE) followed by chromatographic analysis. The quantification of CA concentrations in both nutrient solutions (after SPE) and plant tissues (after extraction) was conducted by chromatographic analysis. CA concentrations of 5.4-26.8 μg g(-1) (fresh weight) were detected in the roots and 7.2-34.6 μg g(-1) (fresh weight) in the shoots after 21 days. Mass balance calculations showed that S. validus uptake alone accounted for a significant contribution (6-13% for the roots and 22-49% for the shoots) of the total loss of CA. The bioaccumulation factors (BAFs) based on fresh weight for the roots ranged from 6.6 to 23.2, while values for the shoots ranged from 9.5 to 32.1. All the BAFs for the shoots were greater than those in the roots, implying that CA has greater tendency to be translocated to the shoots, rather than the roots of S. validus. All the shoot-to-root concentration ratios were more than 1, denoting that the shoots of S. validus do preferentially accumulate CA. We demonstrated that CA can be actively taken up, subsequently translocated and accumulated by aboveground tissues of S. validus. Since S. validus could account for the removal of 28-62% of the total mass loss of CA from the system, such phytoremediation technology has great potential for the removal of pharmaceuticals such as CA from inflowing waters.

Soil Aeration deficiencies in urban sites

NASA Astrophysics Data System (ADS)

Weltecke, Katharina; Gaertig, Thorsten

2010-05-01

Soil aeration deficiencies in urban sites Katharina Weltecke and Thorsten Gaertig On urban tree sites reduction of soil aeration by compaction or sealing is an important but frequently underestimated factor for tree growth. Up to 50% of the CO2 assimilated during the vegetation period is respired in the root space (Qi et al. 1994). An adequate supply of the soil with oxygen and a proper disposal of the exhaled carbon dioxide are essential for an undisturbed root respiration. If the soil surface is smeared, compacted or sealed, soil aeration is interrupted. Several references show that root activity and fine root growth are controlled by the carbon dioxide concentration in soil air (Qi et al.1994, Burton et al. 1997). Gaertig (2001) found that decreasing topsoil gas permeability leads to reduced fine root density and hence to injury in crown structure of oaks. In forest soils a critical CO2 concentration of more than 0.6 % indicates a bad aeration status (Gaertig 2001). The majority of urban tree sites are compacted or sealed. The reduction of soil aeration may lead to dysfunctions in the root space and consequently to stress during periods of drought, which has its visible affects in crown structure. It is reasonable to assume that disturbances in soil aeration lead to reduced tree vigour and roadworthiness, resulting in high maintenance costs. The assessment of soil aeration in urban sites is difficult. In natural ecosystems the measurement of gas diffusivity and the gas-chromatical analysis of CO2 in soil air are accepted procedures in analyzing the state of aeration (Schack-Kirchner et al. 2001, Gaertig 2001). It has been found that these methods can also be applied for analyzing urban sites. In particular CO2 concentration in the soil atmosphere can be considered as a rapidly assessable, relevant and integrating indicator of the aeration situation of urban soils. This study tested the working hypothesis that soil aeration deficiencies lead to a decrease of fine root density and tree vigour on urban soils. For that purpose gas diffusivity, soil CO2 concentrations and fine root density were measured on typical urban sites in the German cities of Göttingen, Mannheim, and Kassel. The known characteristics of soil aeration on forest sites could be affirmed for urban soils. A negative correlation was found between gas diffusion coefficients and CO2 concentration as well as between fine root extension and CO2 concentration. Changes in crown structure of beech indicating a loss of vigour were found at sites with disturbed aeration. Diffusivity patterns and CO2 concentrations of different specific urban soil sealing types were found. On more natural sites (mulch, grass) increased gas diffusion and low CO2 concentration were present. In contrast, on more compacted or sealed areas (asphalt, paving stone, macadamised road surface) the exchange between soil air and atmosphere was nearly disconnected and soil CO2 concentrations partly exceeded the known critical value of 0.6 % up to tenfold. Literature Burton, A. J.; Pregitzer, K. S.; Zogg, G. P. und Zak D. R. (1997): Effect of measurement CO2 concentrations on sugar maple root respiration. In: Canadian journal of Forest Research, H. 17, S. 421-427. Gaertig, T. (2001): Bodengashaushalt, Feinwurzeln und Vitalität von Eichen. In: Freiburger Bodenkundliche Abhandlungen, H. 40, S. 157. Qi, J.; Marshall, J. D.; Mattson, K. G. (1994): High soil carbon dioxide concentrations inhibit root respiration of Douglas fir. In: New Phytol., Jg. 128, H. 3, S. 435-442. Schack-Kirchner, H.; Gaertig, T.; Wilpert, K. v.; Hildebrand, E. E. (2001): A modified McIntyre and Phillip approach to measure top-soil gas diffusivity in-situ. In: J. Plant Nutr. Soil Sci., Jg. 164, S. 253-258.

Sequestration of precious and pollutant metals in biomass of cultured water hyacinth (Eichhornia crassipes).

PubMed

Newete, Solomon W; Erasmus, Barend F N; Weiersbye, Isabel M; Byrne, Marcus J

2016-10-01

The aim of this study was to investigate the overall root/shoot allocation of metal contaminants, the amount of metal removal by absorption and adsorption within or on the external root surfaces, the dose-response of water hyacinth metal uptake, and phytotoxicity. This was examined in a single-metal tub trial, using arsenic (As), gold (Au), copper (Cu), iron (Fe), mercury (Hg), manganese (Mn), uranium (U), and zinc (Zn). Iron and Mn were also used in low-, medium-, and high-concentration treatments to test their dose effect on water hyacinth's metal uptake. Water hyacinth was generally tolerant to metallotoxicity, except for Cu and Hg. Over 80 % of the total amount of metals removed was accumulated in the roots, of which 30-52 % was adsorbed onto the root surfaces. Furthermore, 73-98 % of the total metal assimilation by water hyacinth was located in the roots. The bioconcentration factor (BCF) of Cu, Hg, Au, and Zn exceeded the recommended index of 1000, which is used in selection of phytoremediating plants, but those of U, As, and Mn did not. Nevertheless, the BCF for Mn increased with the increase of Mn concentration in water. This suggests that the use of BCF index alone, without the consideration of plant biomass and metal concentration in water, is inadequate to determine the potential of plants for phytoremediation accurately. Thus, this study confirms that water hyacinth holds potential for a broad spectrum of phytoremediation roles. However, knowing whether these metals are adsorbed on or assimilated within the plant tissues as well as knowing their allocation between roots and shoots will inform decisions how to re-treat biomass for metal recovery, or the mode of biomass reduction for safe disposal after phytoremediation.

Niche partitioning in arbuscular mycorrhizal communities in temperate grasslands: a lesson from adjacent serpentine and nonserpentine habitats.

PubMed

Kohout, Petr; Doubková, Pavla; Bahram, Mohammad; Suda, Jan; Tedersoo, Leho; Voříšková, Jana; Sudová, Radka

2015-04-01

Arbuscular mycorrhizal fungi (AMF) represent an important soil microbial group playing a fundamental role in many terrestrial ecosystems. We explored the effects of deterministic (soil characteristics, host plant life stage, neighbouring plant communities) and stochastic processes on AMF colonization, richness and community composition in roots of Knautia arvensis (Dipsacaceae) plants from three serpentine grasslands and adjacent nonserpentine sites. Methodically, the study was based on 454-sequencing of the ITS region of rDNA. In total, we detected 81 molecular taxonomical operational units (MOTUs) belonging to the Glomeromycota. Serpentine character of the site negatively influenced AMF root colonization, similarly as higher Fe concentration. AMF MOTUs richness linearly increased along a pH gradient from 3.5 to 5.8. Contrary, K and Cr soil concentration had a negative influence on AMF MOTUs richness. We also detected a strong relation between neighbouring plant community composition and AMF MOTUs richness. Although spatial distance between the sampled sites (c. 0.3-3 km) contributed to structuring AMF communities in K. arvensis roots, environmental parameters were key factors in this respect. In particular, the composition of AMF communities was shaped by the complex of serpentine conditions, pH and available soil Ni concentration. The composition of AMF communities was also dependent on host plant life stage (vegetative vs. generative). Our study supports the dominance of deterministic factors in structuring AMF communities in heterogeneous environment composed of an edaphic mosaic of serpentine and nonserpentine soils. © 2015 John Wiley & Sons Ltd.

Analysis of arsenic and antimony distribution within plants growing at an old mine site in Ouche (Cantal, France) and identification of species suitable for site revegetation.

PubMed

Jana, Ulrike; Chassany, Vincent; Bertrand, Georges; Castrec-Rouelle, Maryse; Aubry, Emmanuel; Boudsocq, Simon; Laffray, Daniel; Repellin, Anne

2012-11-15

One of the objectives of this study was to assess the contamination levels in the tailings of an old antimony mine site located in Ouche (Cantal, France). Throughout the 1.3 ha site, homogenous concentrations of antimony and arsenic, a by-product of the operation, were found along 0-0.5 m-deep profiles. Maximum concentrations for antimony and arsenic were 5780 mg kg(-1) dry tailings and 852 mg kg(-1) dry tailings, respectively. Despite the presence of the contaminants and the low pH and organic matter contents of the tailings, several patches of vegetation were found. Botanical identification determined 12 different genera/species. The largest and most abundant plants were adult pines (Pinus sylvestris), birches (Betula pendula) and the bulrush (Juncus effusus). The distribution of the metalloids within specimens of each genera/species was analysed in order to deduce their concentration and translocation capacities. This was the second goal of this work. All plant specimens were highly contaminated with both metalloids. Most were root accumulators with root to shoot translocation factors <1. Whereas contamination levels were high overall, species with both a low translocation factor and a low root accumulation coefficient were identified as suitable candidates for the complete revegetation of the site. Species combining those characteristics were the perennials P. sylvestris, B. pendula, Cytisus scoparius and the herbaceous Plantago major, and Deschampsia flexuosa. Copyright © 2012 Elsevier Ltd. All rights reserved.

Divergent variations in concentrations of chemical elements among shrub organs in a temperate desert

PubMed Central

He, Mingzhu; Song, Xin; Tian, Fuping; Zhang, Ke; Zhang, Zhishan; Chen, Ning; Li, Xinrong

2016-01-01

Desert shrubs, a dominant component of desert ecosystems, need to maintain sufficient levels of nutrients in their different organs to ensure operation of various physiological functions for the purpose of survival and reproduction. In the present study, we analyzed 10 elements in leaves, stems, and roots of 24 dominant shrub species from 52 sites across a temperate desert ecosystem in northwestern China. We found that concentrations of all 10 elements were higher in leaves than in stems and roots, that non-legumes had higher levels of leaf Na and Mg than did legumes, and that Na was more concentrated in C4 leaves than in C3 leaves. Scaling relationships of elements between the photosynthetic organ (leaf) and non-photosynthetic organs (stem and root) were allometric. Results of principal components analysis (PCA) highlighted the important role of the elements responsible for osmoregulation (K and Na) in water utilization of desert shrubs. Soil properties and taxonomy explained most variation of element concentrations in desert shrubs. Desert shrubs may not be particularly susceptible to future change in climate factors, because most elements (including N, P, K, Ca, Mn, Zn, and Cu) associated with photosynthesis, osmoregulation, enzyme activity, and water use efficiency primarily depend on soil conditions. PMID:26818575

Divergent variations in concentrations of chemical elements among shrub organs in a temperate desert.

PubMed

He, Mingzhu; Song, Xin; Tian, Fuping; Zhang, Ke; Zhang, Zhishan; Chen, Ning; Li, Xinrong

2016-01-28

Desert shrubs, a dominant component of desert ecosystems, need to maintain sufficient levels of nutrients in their different organs to ensure operation of various physiological functions for the purpose of survival and reproduction. In the present study, we analyzed 10 elements in leaves, stems, and roots of 24 dominant shrub species from 52 sites across a temperate desert ecosystem in northwestern China. We found that concentrations of all 10 elements were higher in leaves than in stems and roots, that non-legumes had higher levels of leaf Na and Mg than did legumes, and that Na was more concentrated in C4 leaves than in C3 leaves. Scaling relationships of elements between the photosynthetic organ (leaf) and non-photosynthetic organs (stem and root) were allometric. Results of principal components analysis (PCA) highlighted the important role of the elements responsible for osmoregulation (K and Na) in water utilization of desert shrubs. Soil properties and taxonomy explained most variation of element concentrations in desert shrubs. Desert shrubs may not be particularly susceptible to future change in climate factors, because most elements (including N, P, K, Ca, Mn, Zn, and Cu) associated with photosynthesis, osmoregulation, enzyme activity, and water use efficiency primarily depend on soil conditions.

Effects of loxoprofen on the apical root resorption during orthodontic tooth movement in rats.

PubMed

Yamamoto, Taeko; Kaku, Masato; Sumi, Hiromi; Yashima, Yuka; Izumino, Jin; Tanimoto, Kotaro

2018-01-01

Studies have revealed that severe apical root resorption during tooth movement is caused by the noninfective inflammatory reaction of apical root tissues. We hypothesized that loxoprofen can suppress apical root resorption during tooth movement. Cyclic tensile force (CTF) of 10 kPa was applied to the human pulp cells for 48 hours by the Flexcell Strain Unit. Loxoprofen (10 and 100 μM) was added to the culture cells, and expression of cyclooxygenase (COX)-1, COX-2, interleukin (IL)-1β, receptor activator of nuclear factor kappa-B ligand (RANKL), tumor necrosis factor (TNF)-α, and macrophage colony-stimulating factor (M-CSF) were examined. To determine the effects of loxoprofen sodium on apical root reabsorption during tooth movement, the upper first molars of 7-week-old rats were subjected to mesial movement by 10g force for 30 days with or without the oral administration of loxoprofen. Gene expression and protein concentration of COX-1, COX-2, IL-1β, TNF-α, RANKL and M-CSF were significantly higher in the CTF group than in the control group. However, these levels were decreased by loxoprofen administration. After orthodontic tooth movement, the expression of IL-1β, TNF-α, RANKL and M-CSF decreased in the loxoprofen group than in the control group by immunohistochemical staining. In comparison to control group, less number of odontoclasts and a decrease in the amount of apical root resorption was observed in the loxoprofen group. Many osteoclasts became visible on the pressure side of the alveolar bone in the both groups, and the amount of tooth movement did not show a significant difference. These findings demonstrate that severe apical root resorption may be suppressed by loxoprofen administration, without a disturbance of tooth movement.

Effects of loxoprofen on the apical root resorption during orthodontic tooth movement in rats

PubMed Central

Sumi, Hiromi; Yashima, Yuka; Izumino, Jin

2018-01-01

Studies have revealed that severe apical root resorption during tooth movement is caused by the noninfective inflammatory reaction of apical root tissues. We hypothesized that loxoprofen can suppress apical root resorption during tooth movement. Cyclic tensile force (CTF) of 10 kPa was applied to the human pulp cells for 48 hours by the Flexcell Strain Unit. Loxoprofen (10 and 100 μM) was added to the culture cells, and expression of cyclooxygenase (COX)-1, COX-2, interleukin (IL)-1β, receptor activator of nuclear factor kappa-B ligand (RANKL), tumor necrosis factor (TNF)-α, and macrophage colony-stimulating factor (M-CSF) were examined. To determine the effects of loxoprofen sodium on apical root reabsorption during tooth movement, the upper first molars of 7-week-old rats were subjected to mesial movement by 10g force for 30 days with or without the oral administration of loxoprofen. Gene expression and protein concentration of COX-1, COX-2, IL-1β, TNF-α, RANKL and M-CSF were significantly higher in the CTF group than in the control group. However, these levels were decreased by loxoprofen administration. After orthodontic tooth movement, the expression of IL-1β, TNF-α, RANKL and M-CSF decreased in the loxoprofen group than in the control group by immunohistochemical staining. In comparison to control group, less number of odontoclasts and a decrease in the amount of apical root resorption was observed in the loxoprofen group. Many osteoclasts became visible on the pressure side of the alveolar bone in the both groups, and the amount of tooth movement did not show a significant difference. These findings demonstrate that severe apical root resorption may be suppressed by loxoprofen administration, without a disturbance of tooth movement. PMID:29694352

The distribution of glutathione and homoglutathione in leaf, root and seed tissue of 73 species across the three sub-families of the Leguminosae.

PubMed

Colville, Louise; Sáez, Clara M Blanco; Lewis, Gwilym P; Kranner, Ilse

2015-07-01

Homoglutathione (γ-glutamyl-cysteinyl-β-alanine) is a homologue of glutathione (γ-glutamyl-cysteinyl-glycine), which is a ubiquitous and indispensable tripeptide in eukaryotes with multi-facetted functions, many of which relate to cellular redox regulation. Homoglutathione is unique to the Leguminosae family, but studies of its occurrence have been restricted to the Papilionoideae subfamily, and almost exclusively to crop species. To determine whether the distribution of homoglutathione in the Leguminosae has a phylogenetic basis the occurrence of homoglutathione was investigated in the leaves, roots and seeds of 73 wild species of Leguminosae, representing 30 tribes across the Caesalpinioideae, Mimosoideae and Papilionoideae subfamilies. Homoglutathione was found only in the Papilionoideae, and was generally restricted to the 'Old World Clade'. It is proposed that homoglutathione may have arisen following a whole genome duplication event after the divergence of the Old World Clade. Homoglutathione is believed to fulfil the same functional roles as glutathione, but this study showed that homoglutathione and glutathione have different tissue-specific distribution patterns. Homoglutathione tended to occur more frequently in root tissue, and higher concentrations were found in leaves and roots, whereas glutathione tended to be present at the highest concentrations in seeds. This may reflect a distinct role for homoglutathione, particularly in roots, or an inability of homoglutathione to functionally replace glutathione in reproductive tissues. However, no relationships with environmental factors or nodulation were observed. Greater understanding of the factors that influence homoglutathione distribution may help to elucidate its unique function in some legume species. Copyright © 2015 Elsevier Ltd. All rights reserved.

Tanacetum vulgare as a bioindicator of trace-metal contamination: a study of a naturally colonized open-pit lignite mine.

PubMed

Jasion, Mateusz; Samecka-Cymerman, Aleksandra; Kolon, Krzysztof; Kempers, Alexander J

2013-10-01

We investigated the possibility of use of Tanacetum vulgare (tansy) as an ecological indicator of metal concentration in a naturally colonized open-pit lignite mine in Bełchatów (Poland). Tanacetum vulgare is the only species growing abundantly and spontaneously in the lignite mine waste dumps. Metal concentrations in roots, stems, leaves, flowers, and soil were measured in dump sites differing in type and time of reclamation and therefore differing in pollution levels. Tanacetum vulgare appeared to be an accumulator of chromium and iron in roots, whereas highest concentrations of manganese and zinc were found in leaves. A high bioaccumulation factor for cadmium (Cd) was observed in dumps and control sites, indicating that even small amounts of Cd in the environment may result in significant uptake by the plant. The lowest concentrations of metals were found in plants from sites situated on dumps reclaimed with argillaceous limestone.

Cluster-root formation and carboxylate release in three Lupinus species as dependent on phosphorus supply, internal phosphorus concentration and relative growth rate

PubMed Central

Wang, Xing; Pearse, Stuart J.; Lambers, Hans

2013-01-01

Background and Aims Some Lupinus species produce cluster roots in response to low plant phosphorus (P) status. The cause of variation in cluster-root formation among cluster-root-forming Lupinus species is unknown. The aim of this study was to investigate if cluster-root formation is, in part, dependent on different relative growth rates (RGRs) among Lupinus species when they show similar shoot P status. Methods Three cluster-root-forming Lupinus species, L. albus, L. pilosus and L. atlanticus, were grown in washed river sand at 0, 7·5, 15 or 40 mg P kg−1 dry sand. Plants were harvested at 34, 42 or 62 d after sowing, and fresh and dry weight of leaves, stems, cluster roots and non-cluster roots of different ages were measured. The percentage of cluster roots, tissue P concentrations, root exudates and plant RGR were determined. Key Results Phosphorus treatments had major effects on cluster-root allocation, with a significant but incomplete suppression in L. albus and L. pilosus when P supply exceeded 15 mg P kg−1 sand. Complete suppression was found in L. atlanticus at the highest P supply; this species never invested more than 20 % of its root weight in cluster roots. For L. pilosus and L. atlanticus, cluster-root formation was decreased at high internal P concentration, irrespective of RGR. For L. albus, there was a trend in the same direction, but this was not significant. Conclusions Cluster-root formation in all three Lupinus species was suppressed at high leaf P concentration, irrespective of RGR. Variation in cluster-root formation among the three species cannot be explained by species-specific variation in RGR or leaf P concentration. PMID:24061491

Cluster-root formation and carboxylate release in three Lupinus species as dependent on phosphorus supply, internal phosphorus concentration and relative growth rate.

PubMed

Wang, Xing; Pearse, Stuart J; Lambers, Hans

2013-11-01

Some Lupinus species produce cluster roots in response to low plant phosphorus (P) status. The cause of variation in cluster-root formation among cluster-root-forming Lupinus species is unknown. The aim of this study was to investigate if cluster-root formation is, in part, dependent on different relative growth rates (RGRs) among Lupinus species when they show similar shoot P status. Three cluster-root-forming Lupinus species, L. albus, L. pilosus and L. atlanticus, were grown in washed river sand at 0, 7·5, 15 or 40 mg P kg(-1) dry sand. Plants were harvested at 34, 42 or 62 d after sowing, and fresh and dry weight of leaves, stems, cluster roots and non-cluster roots of different ages were measured. The percentage of cluster roots, tissue P concentrations, root exudates and plant RGR were determined. Phosphorus treatments had major effects on cluster-root allocation, with a significant but incomplete suppression in L. albus and L. pilosus when P supply exceeded 15 mg P kg(-1) sand. Complete suppression was found in L. atlanticus at the highest P supply; this species never invested more than 20 % of its root weight in cluster roots. For L. pilosus and L. atlanticus, cluster-root formation was decreased at high internal P concentration, irrespective of RGR. For L. albus, there was a trend in the same direction, but this was not significant. Cluster-root formation in all three Lupinus species was suppressed at high leaf P concentration, irrespective of RGR. Variation in cluster-root formation among the three species cannot be explained by species-specific variation in RGR or leaf P concentration.

Plant selective uptake of halogenated flame retardants at an e-waste recycling site in southern China.

PubMed

Wang, Shaorui; Wang, Yan; Luo, Chunling; Li, Jun; Yin, Hua; Zhang, Gan

2016-07-01

The concentrations and homolog patterns of halogenated flame retardants (HFRs) in vegetables grown at an e-waste contaminated site were investigated. Polybrominated diphenyl ethers (PBDEs) were the dominant HFRs in vegetable tissues, with concentrations ranging from 10.3 to 164 ng g(-1) and 1.16-107 ng g(-1) in shoots and roots, respectively, followed by novel brominated flame retardants (NBFRs) and dechlorane plus (DPs). This is an indication that PBDE contamination in vegetables grown around e-waste recycling sites may pose a risk to the local terrestrial ecosystem and residents. In addition, this is the first report on the concentrations and compositions of NBFRs in vegetables around e-waste recycling sites. The HFRs concentrations in vegetables varied greatly with the vegetable species, with the highest concentrations observed in Brassica oleracea var. capitata. Root concentration factors (RCF) decreased with increasing log Kow of HFRs, which indicated that the uptake of HFRs was controlled mainly by log Kow. Dissimilar HFRs profiles in shoots and roots suggested that the uptake and translocation of HFRs by plants were selective, with lower halogenated congeners prone to accumulation in vegetable tissues. Positive relationships between PBDEs and their substitutes were observed in vegetable tissues, suggesting that the replacement of PBDEs by NBFRs has not resulted in an obvious transition in plants within the study area. Copyright © 2016 Elsevier Ltd. All rights reserved.

Concentration/time-dependent dissipation, partitioning and plant accumulation of hazardous current-used pesticides and 2-hydroxyatrazine in sand and soil.

PubMed

Neuwirthová, Natália; Bílková, Zuzana; Vašíčková, Jana; Hofman, Jakub; Bielská, Lucie

2018-07-01

The dissipation, partitioning dynamics and biouptake was measured for selected hazardous current-used pesticides (conazole fungicides: epoxiconazole, flusilazole, tebuconazole; prochloraz, chlorpyrifos, pendimethalin) and for a transformation product (2-hydroxyatrazine) in agricultural soil and quartz sand as representatives of a real and a worst-case scenario. Dissipation, uptake to Lactuca sativa and the freely dissolved concentration along with the organic carbon-normalized sorption coefficients (K oc ) were determined on days 12, 40, and 90 following the application of compounds at three fortification levels (0.1-1.0-10 mg/kg). Conazole fungicides showed similar dissipation patterns and were more persistent in soil than prochloraz, chlorpyrifos and pendimethalin. 2-Hydroxyatrazine showed a concentration-depended decrease in persistency in soil. Lettuce roots were shown to accumulate higher amounts than shoots where the extent of root uptake was driven by compound partitioning. This was evidenced by the ability of freely dissolved concentration (C free ) to reliably (r 2  = 0.94) predict root uptake. Concentration in leaves did not exceed the maximum residue levels (MRLs) for lettuce, which was likely given by the low root-to-shoot translocation factors (TFs) of the tested compounds varying between 0.007 and 0.14. K oc values were in the range of literature values. Sorption to soil was higher than to sand for all compounds, yet following the K oc dynamics compounds did not appear to be sequestered in soil with increasing residence time. From these results, it follows that the tested compounds may persist in soil but since they did not accumulate in lettuce above MRLs, contamination of the food web is unlikely. Copyright © 2018 Elsevier Ltd. All rights reserved.

Karaya root saponin exerts a hypocholesterolemic response in rats fed a high-cholesterol diet.

PubMed

Afrose, Sadia; Hossain, Md S; Maki, Takaaki; Tsujii, Hirotada

2009-05-01

Different sources of saponins are known to have hypocholesterolemic activity with varying degrees of efficacy. We hypothesize that karaya root saponin would efficiently reduce cholesterol. The aim of this study is to examine the comparative hypocholesterolemic effect of karaya root saponin in rats fed a high-cholesterol diet. Sixty male Wister-Imamichi rats were divided into 5 groups of 12 rats each constituting of the following: control group, soybean saponin-supplemented group, karaya root saponin-supplemented group, quillaja saponin-supplemented group, and tea saponin-supplemented group. Compared with the control diet, both the karaya root- and quillaja saponin-supplemented diets significantly reduced (P < .05) serum cholesterol and atherogenic index. Karaya root saponin significantly increased the serum high-density lipoprotein cholesterol, high-density lipoprotein cholesterol/cholesterol ratio, and fecal cholesterol concentrations (P < .05). The triacylglycerol concentration was significantly reduced only in the quillaja saponin-supplemented rats (P < .05). All the tea, soybean, karaya root, and quillaja saponins significantly reduced low-density lipoprotein cholesterol, and the greatest reduction was observed with karaya root saponin. Highest fecal bile acid concentration was found with quillaja saponin, whereas highest liver bile acid concentration was observed with karaya root saponin-supplemented rats (P < .05). These results collectively suggest that karaya root saponin can efficiently reduce serum cholesterol concentration in rats.

The impacts of climate change and belowground herbivory on aphids via primary metabolites

NASA Astrophysics Data System (ADS)

Ryalls, James M. W.

Global climate and atmospheric change (summarised as climate change for brevity) may alter patterns of crop damage by insect herbivores, but little is known about how multiple climate change factors, acting in tandem, shape such interactions. Crucially, the specific plant-mediated mechanisms underpinning these effects remain largely unknown. Moreover, research into the effects of climate change on leguminous plant species, which have the ability to fix atmospheric nitrogen (N2) via their association with root nodule-dwelling rhizobial bacteria, and their associated insect herbivores, is surprisingly scarce considering their increasing importance in terrestrial ecosystems worldwide. Using a model legume, lucerne, otherwise known as alfalfa, Medicago sativa (Fabaceae), and a model pest species, the pea aphid, Acyrthosiphon pisum (Hemiptera: Aphididae), this work addresses how predicted changes in carbon dioxide (CO2) concentrations, temperature and rainfall patterns as well as interactions with other organisms, including the root-feeding weevil Sitona discoideus (Coleoptera: Curculionidae), might shape legume-feeding aphid populations in the future. Recent literature on the impacts of climate change on aphids and the biology and trophic interactions of lucerne aphids specifically were synthesised in chapters one and two, respectively. These chapters highlighted the importance of the interactions between multiple abiotic and biotic variables in shaping aphid population dynamics. Empirical research chapters three to six, using up to five lucerne genotypes (i.e. cultivars) in glasshouse and field experiments, addressed how A. pisum responded to the isolated and combined effects of climate change and root herbivory. In particular, chapter three determined the effects of elevated temperatures (eT) and elevated atmospheric CO2 concentrations (eCO2) on root-feeding S. discoideus larvae and their interaction with A. pisum. Chapter four addressed whether the effects of eT, eCO2 and simulated root damage on aphids could be explained by changes in plant amino acid concentrations. Chapter five built on the mechanistic findings from chapter four to determine whether specific groups of amino acids were responsible for driving the effects of eT and eCO2 on aphid fecundity, longevity and intrinsic rate of increase (rm). Chapter six extended this research to the field to determine the plant-mediated effects of water stress and root herbivory on aphids in a mixed grass-legume system. Lucerne demonstrated an over compensatory growth response to root herbivory by S. discoideus larvae by increasing net root biomass and nodulation by 31% and 45%, respectively. eT negated the positive effects of eCO2 on weevil larval development, as well as on a number of lucerne characteristics (e.g. nodulation and amino acid concentrations) and aphid performance parameters (e.g. population growth, fecundity and rm). Root herbivory by S. discoideus negatively impacted aphids in general, although effects were dependent on feeding duration and herbivore arrival sequence (i.e. whether aphids fed on the plant before or after root herbivory). While drought negatively impacted aphid abundance, potentially via reduced phloem turgor and sap viscosity, the effects of eT, eCO2 and root herbivory on aphids were often driven by concentrations of specific amino acid groups. Nitrogen (N) leached from lacerated lucerne root nodules by S. discoideus led to increased concentrations of N in a neighbouring grass, Phalaris aquatica (Poaceae), with knock-on effects on plant competition and community dynamics. The opposing effects of eT and eCO2 on plant characteristics and both aboveground and belowground herbivores demonstrates the importance of combining trophic complexity with multiple climatic factors as a means of gaining realistic insights into how insect and plant communities will respond under future conditions. Identifying the specific amino acid changes underpinning aphid responses to climate change and root herbivory offers the potential for breeding aphid resistance traits into lucerne cultivars and informing adaptation strategies against future threats. Changes in precipitation patterns and plant-mediated indirect aboveground-belowground herbivore interactions can alter the outcome of competition between N-fixing legumes and non-N-fixing grasses, with important implications for plant community structure and productivity. Avenues for future research are explored and other causal agents of changes in aphid performance are discussed, which may further elucidate the mechanisms underpinning climate change and belowground herbivory impacts on aphid pests.

Differential exudation of two benzoxazinoids--one of the determining factors for seedling allelopathy of Triticeae species.

PubMed

Belz, Regina G; Hurle, Karl

2005-01-26

Benzoxazinoids (Bx) are natural phytotoxins that function as chemical defense compounds in several species. The release of Bx by intact plant roots associated these compounds with root allelopathy in Triticeae species; however, the significance of exudate concentrations of Bx for plant-plant interactions is still a controversial question. A biological screening of 146 cultivars of four Triticeae species (Triticum aestivum L., Triticum durum Desf., Triticum spelta L., and Secale cereale L.) demonstrated a high cultivar dependence to suppress the root growth of Sinapis alba L. by root allelopathy in a dose-response bioassay. Only a few cultivars possessed a marked high or low allelopathic activity, whereby high-performance liquid chromatography-diode array detection analysis of root exudates revealed that these cultivars differed considerably in their ability to exude the two Bx aglucones, DIBOA [2,4-dihydroxy-2H-1,4-benzoxazin-3(4H)-one] and DIMBOA [2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one]. The total amount of DIBOA and DIMBOA exuded showed a significant correlation to the growth inhibition in bioassay with a statistically estimated contribution to the overall allelopathic effect of 48-72%. In a bioassay with pure phytotoxins, Bx concentrations consistent with the amounts quantified in the screening bioassay caused detrimental effects on S. alba and almost reproduced the statistically estimated contribution. The observed causal association between the allelopathic activity under laboratory conditions and the exudate concentrations of Bx suggests that this association might have implications for the interference of Triticeae species in natural plant communities.

Bio-remediation of Pb and Cd polluted soils by switchgrass: A case study in India.

PubMed

Arora, Kalpana; Sharma, Satyawati; Monti, Andrea

2016-01-01

In the present study bioremediation potential of a high biomass yielding grass, Panicum virgatum (switchgrass), along with plant associated microbes (AM fungi and Azospirillum), was tested against lead and cadmium in pot trials. A pot trial was set up in order to evaluate bioremediation efficiency of P. virgatum in association with PAMs (Plant Associated Microbes). Growth parameters and bioremediation potential of endomycorrhizal fungi (AMF) and Azospirillum against different concentrations of Pb and Cd were compared. AM fungi and Azospirillum increased the root length, branches, surface area, and root and shoot biomass. The soil pH was found towards neutral with AMF and Azospirillum inoculations. The bioconcentration factor (BCF) for Pb (12 mg kg(-1)) and Cd (10 mg kg(-1)) were found to be 0.25 and 0.23 respectively and translocation index (Ti) was 17.8 and 16.7 respectively (approx 45% higher than control). The lower values of BCF and Ti, even at highest concentration of Pb and Cd, revealed the capability of switchgrass of accumulating high concentration of Pb and Cd in the roots, while preventing the translocation of Pb and Cd to aerial biomass.

Actin polymerization drives polar growth in Arabidopsis root hair cells.

PubMed

Vazquez, Luis Alfredo Bañuelos; Sanchez, Rosana; Hernandez-Barrera, Alejandra; Zepeda-Jazo, Isaac; Sánchez, Federico; Quinto, Carmen; Torres, Luis Cárdenas

2014-01-01

In plants, the actin cytoskeleton is a prime regulator of cell polarity, growth, and cytoplasmic streaming. Tip growth, as observed in root hairs, caulonema, and pollen tubes, is governed by many factors, including calcium gradients, exocytosis and endocytosis, reactive oxygen species, and the cytoskeleton. Several studies indicate that the polymerization of G-actin into F-actin also contributes to tip growth. The structure and function of F-actin within the apical dome is variable, ranging from a dense meshwork to sparse single filaments. The presence of multiple F-actin structures in the elongating apices of tip-growing cells suggests that this cytoskeletal array is tightly regulated. We recently reported that sublethal concentrations of fluorescently labeled cytochalasin could be used to visualize the distribution of microfilament plus ends using fluorescence microscopy, and found that the tip region of the growing root hair cells of a legume plant exhibits a clear response to the nodulation factors secreted by Rhizobium. (1) In this current work, we expanded our analysis using confocal microscopy and demonstrated the existence of highly dynamic fluorescent foci along Arabidopsis root hair cells. Furthermore, we show that the strongest fluorescence signal accumulates in the tip dome of the growing root hair and seems to be in close proximity to the apical plasma membrane. Based on these findings, we propose that actin polymerization within the dome of growing root hair cells regulates polar growth.

Multiscale segmentation-aided digital image correlation for strain concentration characterization of a turbine blade fir-tree root

NASA Astrophysics Data System (ADS)

Sun, Chen; Zhou, Yihao; Li, Yang; Chen, Jubing; Miao, Hong

2018-04-01

In this paper, a multiscale segmentation-aided digital image correlation method is proposed to characterize the strain concentration of a turbine blade fir-tree root during its contact with the disk groove. A multiscale approach is implemented to increase the local spatial resolution, as the strain concentration area undergoes highly non-uniform deformation and its size is much smaller than the contact elements. In this approach, a far-field view and several near-field views are selected, aiming to get the full-field deformation and local deformation simultaneously. To avoid the interference of different cameras, only the optical axis of the far-field camera is selected to be perpendicular to the specimen surface while the others are inclined. A homography transformation is optimized by matching the feature points, to rectify the artificial deformation caused by the inclination of the optical axis. The resultant genuine near-field strain is thus obtained after the transformation. A real-world experiment is carried out and the strain concentration is characterized. The strain concentration factor is defined accordingly to provide a quantitative analysis.

Effect of arbuscular mycorrhizal fungi on trace metal uptake by sunflower plants grown on cadmium contaminated soil.

PubMed

Hassan, Saad Eldin; Hijri, Mohamed; St-Arnaud, Marc

2013-09-25

Trace metal (TM) pollution of soil is a worldwide problem that threatens the quality of human and environmental health. Phytoremediation using plants and their associated microbes has been increasingly used as a green technology for cleaning up TM-polluted soils. In this study, we investigated the effect of inoculating two arbuscular mycorrhizal fungal isolates, Rhizophagus irregularis and Funneliformis mosseae, on trace metal uptake by sunflower plants grown in soils contaminated with three different Cd concentrations in a greenhouse trial. Root colonization, plant dry mass, and plant tissue cadmium (Cd), zinc (Zn), and copper (Cu) concentrations in roots and shoots were determined after sunflower harvesting. We found that root mycorrhizal colonization rates were not significantly affected by Cd treatments. At low soil Cd concentration, R. irregularis-inoculated plants had significantly higher shoot Cd and Zn concentrations than plants inoculated with F. mosseae and non-inoculated plants. However, at high soil Cd concentrations, F. mosseae-inoculated plants had significantly lower shoot Cd and Zn concentrations and biological concentration factor (BCF) values than plants inoculated with R. irregularis and non-inoculated plants. Cadmium was mainly translocated in shoot tissues of R. irregularis-inoculated plants and sequestered in the rhizosphere of F. mosseae-inoculated plants. The results indicate that these AMF strains mediate different tolerance strategies to alleviate TM toxicity in their host plants and that inoculation with the R. irregularis strain can be used for Cd phytoextraction, whereas this F. mosseae strain can be useful for Cd and Zn phytostabilization of contaminated soil. Copyright © 2013 Elsevier B.V. All rights reserved.

Concentration of Elements in Food: How Can It Reflect Impact of Environmental and Other Influencing Factors?

NASA Astrophysics Data System (ADS)

Vincevica-Gaile, Zane; Klavins, Maris

2013-12-01

Element content of food is variable and can be influenced by different factors. The aim of the present study was to discover the linkage between macro- and microelement concentrations in food produced in Latvia, and possible impacts of environmental factors. More than 300 fresh food samples such as eggs, cottage cheese, honey, root vegetables, apple juice, apple wine were collected in the time period from 2009 to 2011. Samples were mineralised or analysed directly by appropriate method of quantitative analysis: atomic absorption spectrometry, inductively coupled plasma mass spectrometry or total reflection X-ray fluorescence spectrometry. Statistical analysis of data revealed that food elemental content can be influenced by sitespecific factors such as geographical origin, seasonality, environmental pollution.

Distribution of glucosinolates and sulphur-rich cells in roots of field-grown canola (Brassica napus).

PubMed

McCully, Margaret E; Miller, Celia; Sprague, Susan J; Huang, Cheng X; Kirkegaard, John A

2008-01-01

To investigate the role played by the distribution pattern of glucosinolates (GSLs) in root systems in the release of biocides to the rhizosphere, GSLs have been localized, for the first time, to specific regions and cells in field-grown roots. GSL concentrations in separated tissues of canola (Brassica napus) were determined by chemical analysis, and cell-specific concentrations by extrapolation from sulphur concentrations obtained by quantitative cryo-analytical scanning electron microscopy (SEM). In roots with secondary growth, GSL concentrations in the outer secondary tissues were up to 5x those of the inner core. The highest GSL concentrations (from sulphur measurements) were in two cell layers just under the outermost periderm layer, with up to 100x published concentrations for whole roots. Primary tissues had negligible GSL. Release and renewal of the peripheral GSLs is probably a normal developmental process as secondary thickening continues and surface cells senesce, accounting for published observations that intact roots release GSLs and their biocide hydrolosates to the rhizosphere. Absence of myrosin idioblasts close to the root surface suggests that GSLs released developmentally are hydrolysed by myrosinase in the rhizosphere, ensuring a continuous localized source of biotoxic hydrolysates which can deter soil-borne pests, and influence microbial populations associated with long-lived components of the root system.

Comparison of Glucosinolate Profiles in Different Tissues of Nine Brassica Crops.

PubMed

Bhandari, Shiva Ram; Jo, Jung Su; Lee, Jun Gu

2015-08-31

Glucosinolate (GSL) profiles and concentrations in various tissues (seeds, sprouts, mature root, and shoot) were determined and compared across nine Brassica species, including cauliflower, cabbage, broccoli, radish, baemuchae, pakchoi, Chinese cabbage, leaf mustard, and kale. The compositions and concentrations of individual GSLs varied among crops, tissues, and growth stages. Seeds had highest total GSL concentrations in most of crops, whereas shoots had the lowest GSL concentrations. Aliphatic GSL concentrations were the highest in seeds, followed by that in sprouts, shoots, and roots. Indole GSL concentration was the highest in the root or shoot tissues in most of the crops. In contrast, aromatic GSL concentrations were highest in roots. Of the nine crops examined, broccoli exhibited the highest total GSL concentration in seeds (110.76 µmol·g(-1)) and sprouts (162.19 µmol·g(-1)), whereas leaf mustard exhibited the highest total GSL concentration in shoots (61.76 µmol·g(-1)) and roots (73.61 µmol·g(-1)). The lowest GSL concentrations were observed in radish across all tissues examined.

Assessment of grass root effects on soil piping in sandy soils using the pinhole test

NASA Astrophysics Data System (ADS)

Bernatek-Jakiel, Anita; Vannoppen, Wouter; Poesen, Jean

2017-10-01

Soil piping is an important land degradation process that occurs in a wide range of environments. Despite an increasing number of studies on this type of subsurface erosion, the impact of vegetation on piping erosion is still unclear. It can be hypothesized that vegetation, and in particular plant roots, may reduce piping susceptibility of soils because roots of vegetation also control concentrated flow erosion rates or shallow mass movements. Therefore, this paper aims to assess the impact of grass roots on piping erosion susceptibility of a sandy soil. The pinhole test was used as it provides quantitative data on pipeflow discharge, sediment concentration and sediment discharge. Tests were conducted at different hydraulic heads (i.e., 50 mm, 180 mm, 380 mm and 1020 mm). Results showed that the hydraulic head was positively correlated with pipeflow discharge, sediment concentration and sediment discharge, while the presence of grass roots (expressed as root density) was negatively correlated with these pipeflow characteristics. Smaller sediment concentrations and sediment discharges were observed in root-permeated samples compared to root-free samples. When root density exceeds 0.5 kg m- 3, piping erosion rates decreased by 50% compared to root-free soil samples. Moreover, if grass roots are present, the positive correlation between hydraulic head and both sediment discharge and sediment concentration is less pronounced, demonstrating that grass roots become more effective in reducing piping erosion rates at larger hydraulic heads. Overall, this study demonstrates that grass roots are quite efficient in reducing piping erosion rates in sandy soils, even at high hydraulic head (> 1 m). As such, grass roots may therefore be used to efficiently control piping erosion rates in topsoils.

Early changes of the pH of the apoplast are different in leaves, stem and roots of Vicia faba L. under declining water availability.

PubMed

Karuppanapandian, T; Geilfus, C-M; Mühling, K-H; Novák, O; Gloser, V

2017-02-01

Changes in pH of the apoplast have recently been discussed as an important factor in adjusting transpiration and water relations under conditions of drought via modulatory effect on abscisic acid (ABA) concentration. Using Vicia faba L., we investigated whether changes in the root, shoot and leaf apoplastic pH correlated with (1) a drought-induced reduction in transpiration and with (2) changes in ABA concentration. Transpiration, leaf water potential and ABA in leaves were measured and correlated with root and shoot xylem pH, determined by a pH microelectrode, and pH of leaf apoplast quantified by microscopy-based in vivo ratiometric analysis. Results revealed that a reduction in transpiration rate in the early phase of soil drying could not be linked with changes in the apoplastic pH via effects on the stomata-regulating hormone ABA. Moreover, drought-induced increase in pH of xylem or leaf apoplast was not the remote effect of an acropetal transport of alkaline sap from root, because root xylem acidified during progressive soil drying, whereas the shoot apoplast alkalized. We reason that other, yet unknown signalling mechanism was responsible for reduction of transpiration rate in the early phase of soil drying. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Towards the discovery of novel genetic component involved in stress resistance in Arabidopsis thaliana.

PubMed

Juraniec, Michal; Lequeux, Hélène; Hermans, Christian; Willems, Glenda; Nordborg, Magnus; Schneeberger, Korbinian; Salis, Pietrino; Vromant, Maud; Lutts, Stanley; Verbruggen, Nathalie

2014-02-01

The exposure of plants to high concentrations of trace metallic elements such as copper involves a remodeling of the root system, characterized by a primary root growth inhibition and an increase in the lateral root density. These characteristics constitute easy and suitable markers for screening mutants altered in their response to copper excess. A forward genetic approach was undertaken in order to discover novel genetic factors involved in the response to copper excess. A Cu(2+) -sensitive mutant named copper modified resistance1 (cmr1) was isolated and a causative mutation in the CMR1 gene was identified by using positional cloning and next-generation sequencing. CMR1 encodes a plant-specific protein of unknown function. The analysis of the cmr1 mutant indicates that the CMR1 protein is required for optimal growth under normal conditions and has an essential role in the stress response. Impairment of the CMR1 activity alters root growth through aberrant activity of the root meristem, and modifies potassium concentration and hormonal balance (ethylene production and auxin accumulation). Our data support a putative role for CMR1 in cell division regulation and meristem maintenance. Research on the role of CMR1 will contribute to the understanding of the plasticity of plants in response to changing environments. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Fine root biomass, necromass and chemistry during seven years of elevated aluminium concentrations in the soil solution of a middle-aged Picea abies stand.

PubMed

Eldhuset, Toril D; Lange, Holger; de Wit, Helene A

2006-10-01

Toxic effects of aluminium (Al) on Picea abies (L.) Karst. (Norway spruce) trees are well documented in laboratory-scale experiments, but field-based evidence is scarce. This paper presents results on fine root growth and chemistry from a field manipulation experiment in a P. abies stand that was 45 years old when the experiment started in 1996. Different amounts of dissolved aluminium were added as AlCl3 by means of periodic irrigation during the growing season in the period 1997-2002. Potentially toxic concentrations of Al in the soil solution were obtained. Fine roots were studied from direct cores (1996) and sequential root ingrowth cores (1999, 2001, 2002) in the mineral soil (0-40 cm). We tested two hypotheses: (1) elevated concentration of Al in the root zone leads to significant changes in root biomass, partitioning into fine, coarse, living or dead fractions, and distribution with depth; (2) elevated Al concentration leads to a noticeable uptake of Al and reduced uptake of Ca and Mg; this results in Ca and Mg depletion in roots. Hypothesis 1 was only marginally supported, as just a few significant treatment effects on biomass were found. Hypothesis 2 was supported in part; Al addition led to increased root concentrations of Al in 1999 and 2002 and reduced Mg/Al in 1999. Comparison of roots from subsequent root samplings showed a decrease in Al and S over time. The results illustrated that 7 years of elevated Al(tot) concentrations in the soil solution up to 200 microM are not likely to affect root growth. We also discuss possible improvements of the experimental approach.

Melatonin enhances root regeneration, photosynthetic pigments, biomass, total carbohydrates and proline content in the cherry rootstock PHL-C (Prunus avium × Prunus cerasus).

PubMed

Sarropoulou, Virginia; Dimassi-Theriou, Kortessa; Therios, Ioannis; Koukourikou-Petridou, Magdalene

2012-12-01

The present study, investigates the effects of melatonin (0, 0.05, 0.1, 0.5, 1, 5 and 10 μM) on the morphogenic and biochemical responses in the cherry rootstock PHL-C (Prunus avium L. × Prunus cerasus L.), from shoot tip explants. The incorporation of melatonin (0-10 μM) in the Murashige and Skoog (MS) medium, greatly influenced rooting either positively or negatively. Melatonin, irrespective of its concentration, had a negative effect concerning the number of roots. However, application of 0.5 μM melatonin significantly increased the root length; while 1 μM melatonin increased the root length by 2.5 times, and the fresh weight of the roots by 4 times, in comparison to the control. Although 0.05 μM melatonin increased rooting by 11.11%, 5 μM melatonin had a significant reduction on the number, the fresh weight of roots, and the rooting percentage. Melatonin concentration of 0.1 μM resulted in the greatest chlorophyll (a + b) content, and 5-10 μM reduced the chlorophyll concentration by 2 times, compared to the control. The high melatonin concentrations (5 and 10 μM), increased the levels of proline and carbohydrates in leaves by 3-4 times. In the roots, 0.5 μM of melatonin concentration increased the carbohydrate levels by 1.5 times, while 0.05, 0.1 and 1 μM melatonin concentration significantly reduced the proline content. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Linearity assumption in soil-to-plant transfer factors of natural uranium and radium in Helianthus annuus L.

PubMed

Rodríguez, P Blanco; Tomé, F Vera; Fernández, M Pérez; Lozano, J C

2006-05-15

The linearity assumption of the validation of soil-to-plant transfer factors of natural uranium and (226)Ra was tested using Helianthus annuus L. (sunflower) grown in a hydroponic medium. Transfer of natural uranium and (226)Ra was tested in both the aerial fraction of plants and in the overall seedlings (roots and shoots). The results show that the linearity assumption can be considered valid in the hydroponic growth of sunflowers for the radionuclides studied. The ability of sunflowers to translocate uranium and (226)Ra was also investigated, as well as the feasibility of using sunflower plants to remove uranium and radium from contaminated water, and by extension, their potential for phytoextraction. In this sense, the removal percentages obtained for natural uranium and (226)Ra were 24% and 42%, respectively. Practically all the uranium is accumulated in the roots. However, 86% of the (226)Ra activity concentration in roots was translocated to the aerial part.

Interactive Effects of CO2 and O2 in Soil on Root and Top Growth of Barley and Peas

PubMed Central

Geisler, G.

1967-01-01

Barley and pea plants were grown under several regimens of different compositions of soil atmosphere, the O2 concentration varying from 0 to 21% and the CO2 concentration from 0 to 8%. In absence of CO2, the effect of O2 on root length in barley was characterized by equal root lengths within the range of 21 to 7% O2 and a steep decline between 7 and 0%. In peas, while showing the same general response, the decline occurred between 14 and 7% O2. Root numbers of the seminal roots of barley decreased already with reduction in O2 concentration from 21 to 14%. Dry matter production was affected somewhat differently by O2 and CO2 concentration. Dry matter production in barley was reduced at 14% O2 while root length decreased between 7 and 0%. In peas, dry matter production was favored by low CO2 concentrations except where there was no oxygen. At 21% O2, increasing CO2 concentrations did not seem to affect root length up to concentrations of 2% CO2. At 8% CO2, root length was decreased. The inter-active effects of CO2 and O2 are characterized by a reduced susceptibility to CO2 at O2 values below 7%, and a very deleterious effect of 8% CO2 at 7% O2. PMID:16656508

The development of the rhizosphere: simulation of root exudation for two contrasting exudates: citrate and mucilage

NASA Astrophysics Data System (ADS)

Sheng, Cheng; Bol, Roland; Vetterlein, Doris; Vanderborght, Jan; Schnepf, Andrea

2017-04-01

Different types of root exudates and their effect on soil/rhizosphere properties have received a lot of attention. Since their influence of rhizosphere properties and processes depends on their concentration in the soil, the assessment of the spatial-temporal exudate concentration distribution around roots is of key importance for understanding the functioning of the rhizosphere. Different root systems have different root architectures. Different types of root exudates diffuse in the rhizosphere with different diffusion coefficient. Both of them are responsible for the dynamics of exudate concentration distribution in the rhizosphere. Hence, simulations of root exudation involving four kinds of plant root systems (Vicia faba, Lupinus albus, Triticum aestivum and Zea mays) and two kinds of root exudates (citrate and mucilage) were conducted. We consider a simplified root architecture where each root is represented by a straight line. Assuming that root tips move at a constant velocity and that mucilage transport is linear, concentration distributions can be obtained from a convolution of the analytical solution of the transport equation in a stationary flow field for an instantaneous point source injection with the spatial-temporal distribution of the source strength. By coupling the analytical equation with a root growth model that delivers the spatial-temporal source term, we simulated exudate concentration distributions for citrate and mucilage with MATLAB. From the simulation results, we inferred the following information about the rhizosphere: (a) the dynamics of the root architecture development is the main effect of exudate distribution in the root zone; (b) a steady rhizosphere with constant width is more likely to develop for individual roots when the diffusion coefficient is small. The simulations suggest that rhizosphere development depends in the following way on the root and exudate properties: the dynamics of the root architecture result in various development patterns of the rhizosphere. Meanwhile, Results improve our understanding of the impact of the spatial and temporal heterogeneity of exudate input on rhizosphere development for different root system types and substances. In future work, we will use the simulation tool to infer critical parameters that determine the spatial-temporal extent of the rhizosphere from experimental data.

Potential for Phytoextraction of Cu by Sesamum indicum L. and Cyamopsis tetragonoloba L.: A Green Solution to Decontaminate Soil

NASA Astrophysics Data System (ADS)

Amin, Hira; Arain, Basir Ahmed; Abbasi, Muhammad Sadiq; Jahangir, Taj Muhammad; Amin, Farah

2018-02-01

Phytoextraction is a plant based-technique for removing toxic heavy metals from polluted soil. The experiment reported in this paper was undertaken to study the basic Cu phytoextraction potential of Sesamum indicum in comparison with Cyamopsis tetragonoloba for remediation of Cu contaminated soil in the framework of a pot-experiment. Plants were subjected to seven Cu concentrations (0, 25, 50, 100, 150, 200, and 300 mg kg-1 soil) for 12 weeks. The morphological (i.e. growth) and biochemical (i.e. chlorophyll) parameters of both the plant species were observed throughout the experimental period; the phytoextraction efficiency of S. indicum and C. tetragonoloba were also determined. Most growth parameters were reduced under high Cu stress. Our results shows that at low concentration (25 mg Cu kg-1) all the growth and biochemical parameters were increased but at elevated Cu concentrations, root length, shoot length, and biomass (fresh and dry) were all significantly decreased (p < 0.05). Chlorophyll contents also declined with increasing concentrations of Cu, when compared with control. A consistent increase of Cu accumulation in root and shoot of both S. indicum and C. tetragonoloba with rising concentrations of Cu in soil was noted for all tested treatments. In this study, both plant species showed quite high Cu tolerance and accumulation efficiency, even though C. tetragonoloba have higher Cu accumulation and tolerance indices than that of S. indicum. At 300 mg Cu kg-1, the highest Cu concentration was found in the root (282.08 mg Cu kg-1) followed by leaf (105.78 mg Cu kg-1), stem (65.30 mg Cu kg-1), and pod (8.13 mg Cu kg-1) of S. indicum. In contrast, C. tetragonoloba had highest Cu concentration primarily in the root (158.45 mg Cu kg-1) followed by the stem (154.73 mg Cu kg-1), leaf (152.32 mg Cu kg-1), and pod (8.13 mg Cu kg-1). Considering rapid growth, high biomass, tolerance, accumulation efficiency, bioconcentration factor (BCF) > 1, bioaccumulation coefficient (BAC) > 1 and translocation factor (TF) > 1 established C. tetragonoloba as a potential candidate plant for the decontamination of slightly Cu-polluted soil where the growth of plants would not be impaired and the extraction of Cu could be maintained at satisfying levels. Therefore, the present study suggested that C. tetragonoloba could possibly be used as a viable tool for phytoextraction.

Potential for Phytoextraction of Cu by Sesamum indicum L. and Cyamopsis tetragonoloba L.: A Green Solution to Decontaminate Soil

NASA Astrophysics Data System (ADS)

Amin, Hira; Arain, Basir Ahmed; Abbasi, Muhammad Sadiq; Jahangir, Taj Muhammad; Amin, Farah

2018-05-01

Phytoextraction is a plant based-technique for removing toxic heavy metals from polluted soil. The experiment reported in this paper was undertaken to study the basic Cu phytoextraction potential of Sesamum indicum in comparison with Cyamopsis tetragonoloba for remediation of Cu contaminated soil in the framework of a pot-experiment. Plants were subjected to seven Cu concentrations (0, 25, 50, 100, 150, 200, and 300 mg kg-1 soil) for 12 weeks. The morphological (i.e. growth) and biochemical (i.e. chlorophyll) parameters of both the plant species were observed throughout the experimental period; the phytoextraction efficiency of S. indicum and C. tetragonoloba were also determined. Most growth parameters were reduced under high Cu stress. Our results shows that at low concentration (25 mg Cu kg-1) all the growth and biochemical parameters were increased but at elevated Cu concentrations, root length, shoot length, and biomass (fresh and dry) were all significantly decreased ( p < 0.05). Chlorophyll contents also declined with increasing concentrations of Cu, when compared with control. A consistent increase of Cu accumulation in root and shoot of both S. indicum and C. tetragonoloba with rising concentrations of Cu in soil was noted for all tested treatments. In this study, both plant species showed quite high Cu tolerance and accumulation efficiency, even though C. tetragonoloba have higher Cu accumulation and tolerance indices than that of S . indicum. At 300 mg Cu kg-1, the highest Cu concentration was found in the root (282.08 mg Cu kg-1) followed by leaf (105.78 mg Cu kg-1), stem (65.30 mg Cu kg-1), and pod (8.13 mg Cu kg-1) of S. indicum. In contrast, C. tetragonoloba had highest Cu concentration primarily in the root (158.45 mg Cu kg-1) followed by the stem (154.73 mg Cu kg-1), leaf (152.32 mg Cu kg-1), and pod (8.13 mg Cu kg-1). Considering rapid growth, high biomass, tolerance, accumulation efficiency, bioconcentration factor (BCF) > 1, bioaccumulation coefficient (BAC) > 1 and translocation factor (TF) > 1 established C. tetragonoloba as a potential candidate plant for the decontamination of slightly Cu-polluted soil where the growth of plants would not be impaired and the extraction of Cu could be maintained at satisfying levels. Therefore, the present study suggested that C. tetragonoloba could possibly be used as a viable tool for phytoextraction.

Bioaccumulation and translocation of metals in the natural vegetation growing on fly ash lagoons: a field study from Santaldih thermal power plant, West Bengal, India.

PubMed

Maiti, Subodh Kumar; Jaiswal, Shishir

2008-01-01

A field study was conducted in the fly ash lagoons of Santandih Thermal Power Plant located in West Bengal (India) to find out total, EDTA and DTPA extractable metals in fly ash and their bioaccumulation in root and shoot portion of the naturally growing vegetation. Fly ash sample has alkaline pH and low conductivity. The concentration of total Cu, Zn, Pb and Ni were found higher than weathered fly ash and natural soil, where as Co, Cd and Cr were found traces. Five dominant vegetation namely, Typha latifolia, Fimbristylis dichotoma, Amaranthus defluxes, Saccharum spontaenum and Cynodon dactylon were collected in the winter months (November-December). Bioaccumulation of metals in root and shoot portions were found varied significantly among the species, but all concentration were found within toxic limits. Correlation between total, DTPA and EDTA extractable metals viz. root and shoot metals concentration were studied. Translocation factor (TF) for Cu, Zn and Ni were found less than unity, indicates that these metals are immobilized in the root part of the plants. Metals like Mn have TF greater than unity. The study infers that natural vegetation removed Mn by phytoextraction mechanisms (TF > 1), while other metals like Zn, Cu, Pb and Ni were removed by rhizofiltration mechanisms (TF < 1). The field study revealed that T. latifolia and S. spontaenum plants could be used for bioremediation of fly ash lagoon.

Waving and skewing: how gravity and the surface of growth media affect root development in Arabidopsis.

PubMed

Oliva, Michele; Dunand, Christophe

2007-01-01

Arabidopsis seedlings growing on inclined agar surfaces exhibit characteristic root behaviours called 'waving' and 'skewing': the former consists of a series of undulations, whereas the latter is a deviation from the direction of gravity. Even though the precise basis of these growth patterns is not well understood, both gravity and the contact between the medium and the root are considered to be the major players that result in these processes. The influence of these forces on root surface-dependent behaviours can be verified by growing seedlings at different gel pitches: plants growing on vertical plates present roots with slight waving and skewing when compared with seedlings grown on plates held at minor angles of < 90 degrees . However, other factors are thought to modulate root growth on agar; for instance, it has been demonstrated that the presence and concentration of certain compounds in the medium (such as sucrose) and of drugs able to modify the plant cell cytoskeleton also affect skewing and waving. The recent discovery of an active role of ethylene on surface-dependent root behaviour, and the finding of new mutants showing anomalous growth, pave the way for a more detailed description of these phenomena.

Application of a single root-scale model to improve macroscopic modeling of root water uptake: focus on osmotic stress

NASA Astrophysics Data System (ADS)

Jorda, Helena; Perelman, Adi; Lazarovitch, Naftali; Vanderborght, Jan

2017-04-01

Root water uptake is a fundamental process in the hydrological cycle and it largely regulates the water balance in the soil vadose zone. Macroscopic stress functions are currently used to estimate the effect of salinity on root water uptake. These functions commonly assume stress to be a function of bulk salinity and of the plant sensitivity to osmotic stress expressed as the salinity at which transpiration is reduced by half or so called tolerance value. However, they fail to integrate additional relevant factors such as atmospheric conditions or root architectural traits. We conducted a comprehensive simulation study on a single root using a 3-D physically-based model that resolves flow and transport to individual root segments and that couples flow in the soil and root system. The effect of salt concentrations on root water uptake was accounted for by including osmotic water potential gradients between the solution at the soil root interface and the root xylem sap in the hydraulic gradient between the soil and root. A large set of factors were studied, namely, potential transpiration rate and dynamics, root length density (RLD), irrigation water quality and irrigation frequency, and leaching fraction. Results were fitted to the macroscopic function developed by van Genuchten and Hoffman (1984) and the dependency of osmotic stress and the fitted macroscopic parameters on the studied factors was evaluated. Osmotic stress was found to be highly dependent on RLD. Low RLDs result in a larger stress to the plant due to high evaporative demand per root length unit. In addition, osmotic stress was positively correlated to potential transpiration rate, and sinusoidal potential transpiration lead to larger stress than when imposed as a constant boundary condition. Macroscopic parameters are usually computed as single values for each crop and used for the entire growing season. However, our study shows that both tolerance value and shape parameter p from the van Genuchten and Hoffman (1984) function were highly dependent on both potential transpiration and RLD. Plant salt tolerance was lower under high evaporative demand and lower RLD. In addition, the shape of the stress curve, which is defined by p, was found to be steeper under larger RLD and low transpiration rate. Time-variant macroscopic parameters based on knowledge of current potential transpiration rate per root unit length would be more convenient to accurately predict osmotic stress, and hence root water uptake, during a growing season. In a next step, simulations considering the whole root systems will be conducted to assess how macroscopic parameters are also related to root architectural characteristics. van Genuchten, M.T., Hoffman, G., 1984. Analysis of crop production. Soil Salin. Irrig. Springer Berl. 258-271.

During measurements of root hydraulics with pressure probes, the contribution of unstirred layers is minimized in the pressure relaxation mode: comparison with pressure clamp and high-pressure flowmeter.

PubMed

Knipfer, Thorsten; Das, Debasish; Steudle, Ernst

2007-07-01

The effects of unstirred layers (USLs) at the endodermis of roots of young maize plants (Zea mays L.) were quantified, when measuring the water permeability of roots using a root pressure probe (RPP) in the pressure relaxation (PR) and pressure clamp (PC) modes. Different from PRs, PCs were performed by applying a constant pressure for certain periods of time. Experimental data were compared with results from simulations based on a convection versus diffusion (C/D) model, with the endodermis being the main barrier for solutes and water. Solute profiles in the stele were calculated as they occurred during rapid water flows across the root. The model quantitatively predicted the experimental finding of two distinct phases during PRs, in terms of a build-up of concentration profiles in the stele between endodermis and xylem vessels. It also predicted that, following a PC, half-times (T1/2) of PRs increased as the time used for clamping (and the build-up of USLs) increased. Following PCs of durations of 15, 30 and 60 s, T1/2 increased by factors of between 2.5 and 7.0, and water permeability of roots (root hydraulic conductivity, Lpr) was reduced by the same factors. When root pressure was immediately taken back to the original equilibrium root pressure following a PC, there was a transient uptake of water into the root stele (transient increase of root pressure), and the size of transients rose with time of clamping, as predicted by the model. The results indicated that the 'real' hydraulic conductivity of roots should be measured during initial water flows, such as during the rapid phase of PRs, when the effect of USLs was minimized. It was discussed that 'pressure-propagation effects' could not explain the finding of two phases during PRs. The results of USL effects threw some doubt on the use of PC and high-pressure flowmeter (HPFM) techniques with roots, where rigorous estimates of USLs were still missing despite the fact that large quantities of water were forced across the root.

Phytoremediation of heavy metals from fly ash pond by Azolla caroliniana.

PubMed

Pandey, Vimal Chandra

2012-08-01

Abundance of naturally growing Azolla caroliniana (water fern) on the surface of metal enriched fly ash (FA) pond reflects its toxitolerant characteristics. Results indicate the efficiency of A. caroliniana for phytoremediation of FA pond because of its higher bioconcentration factor. The metal concentration ranged from 175 to 538 and 86 to 753mgkg(-1) in roots and fronds, respectively. Bioconcentration factor (BCF) values of all metals in root and frond ranged from 1.7 to18.6 and 1.8 to 11.0, respectively, which were greater than one and indicates the metal accumulation potential of A. caroliniana. Translocation factor (TF) ranged from 0.37 to 1.4 for various heavy metals. The field result proved that A. caroliniana is a potential accumulator for the examined heavy metals and can be used for phytoremediation of FA pond. Copyright © 2012 Elsevier Inc. All rights reserved.

Ecophysiology of wetland plant roots: A modelling comparison of aeration in relation to species distribution

USGS Publications Warehouse

Sorrell, B.K.; Mendelssohn, I.A.; McKee, K.L.; Woods, R.A.

2000-01-01

This study examined the potential for inter-specific differences in root aeration to determine wetland plant distribution in nature. We compared aeration in species that differ in the type of sediment and depth of water they colonize. Differences in root anatomy, structure and physiology were applied to aeration models that predicted the maximum possible aerobic lengths and development of anoxic zones in primary adventitious roots. Differences in anatomy and metabolism that provided higher axial fluxes of oxygen allowed deeper root growth in species that favour more reducing sediments and deeper water. Modelling identified factors that affected growth in anoxic soils through their effects on aeration. These included lateral root formation, which occurred at the expense of extension of the primary root because of the additional respiratory demand they imposed, reducing oxygen fluxes to the tip and stele, and the development of stelar anoxia. However, changes in sediment oxygen demand had little detectable effect on aeration in the primary roots due to their low wall permeability and high surface impedance, but appeared to reduce internal oxygen availability by accelerating loss from laterals. The development of pressurized convective gas flow in shoots and rhizomes was also found to be important in assisting root aeration, as it maintained higher basal oxygen concentrations at the rhizome-root junctions in species growing into deep water. (C) 2000 Annals of Botany Company.

Root water transport of Helianthus annuus L. under iron oxide nanoparticle exposure.

PubMed

Martínez-Fernández, Domingo; Barroso, Didac; Komárek, Michael

2016-01-01

The application of nanomaterials in commercially available products is increasing rapidly for agriculture, phytoremediation and biotechnology. Since plants suppose the first sink for the accumulation of nanoparticles from the environment, emerging studies have focused on the general consequences for plants and their effects on the biomass production. However, effects on the root surface, as well as blockage of nutrients and water uptake by the roots, may also occur. This experiment was designed to prove if the plant water relations can be affected by the adsorption of nanoparticles on the root surface, causing a consequent stress for the plants. With this goal, plants of Helianthus annuus were previously grown in a hydroponic culture, and at age of 55 days, their roots were exposed to three different concentrations of nanomaghemite (NM) in the hydroponic solution for 5 days: control without NM; 50 and 100 mg l(-1) NM. The main effect was related to the reduction of the root hydraulic conductivity (Lo) and the nutrients uptake. The concentrations of the macronutrients Ca, K, Mg and S in the shoot were reduced relative to the control plants, which resulted in lower contents of chlorophyll pigments. Although stress was not detected in the plants, after the analysis of stress markers like the accumulation of proline or ascorbate in the tissues, reduction of the root functionality by nanoparticles has been identified here, manifested as the effect of NM on Lo. The treatment with 50 mg l(-1) NM significantly reduced the Lo, by up to 57% of its control value, and it was reduced by up to 26% at 100 mg l(-1) NM. These results will be an important factor to take into account with regard to the applicability of NM for long-term use in crops, particularly during privative water conditions.

Plant developmental responses to climate change.

PubMed

Gray, Sharon B; Brady, Siobhan M

2016-11-01

Climate change is multi-faceted, and includes changing concentrations of greenhouse gases in the atmosphere, rising temperatures, changes in precipitation patterns, and increasing frequency of extreme weather events. Here, we focus on the effects of rising atmospheric CO 2 concentrations, rising temperature, and drought stress and their interaction on plant developmental processes in leaves, roots, and in reproductive structures. While in some cases these responses are conserved across species, such as decreased root elongation, perturbation of root growth angle and reduced seed yield in response to drought, or an increase in root biomass in shallow soil in response to elevated CO 2 , most responses are variable within and between species and are dependent on developmental stage. These variable responses include species-specific thresholds that arrest development of reproductive structures, reduce root growth rate and the rate of leaf initiation and expansion in response to elevated temperature. Leaf developmental responses to elevated CO 2 vary by cell type and by species. Variability also exists between C 3 and C 4 species in response to elevated CO 2 , especially in terms of growth and seed yield stimulation. At the molecular level, significantly less is understood regarding conservation and variability in molecular mechanisms underlying these traits. Abscisic acid-mediated changes in cell wall expansion likely underlie reductions in growth rate in response to drought, and changes in known regulators of flowering time likely underlie altered reproductive transitions in response to elevated temperature and CO 2 . Genes that underlie most other organ or tissue-level responses have largely only been identified in a single species in response to a single stress and their level of conservation is unknown. We conclude that there is a need for further research regarding the molecular mechanisms of plant developmental responses to climate change factors in general, and that this lack of data is particularly prevalent in the case of interactive effects of multiple climate change factors. As future growing conditions will likely expose plants to multiple climate change factors simultaneously, with a sum negative influence on global agriculture, further research in this area is critical. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Enzymatic adaptations to arsenic-induced oxidative stress in Zea mays and genotoxic effect of arsenic in root tips of Vicia faba and Zea mays.

PubMed

Duquesnoy, Isabelle; Champeau, Gabrielle Marie; Evray, Germaine; Ledoigt, Gérard; Piquet-Pissaloux, Agnès

2010-01-01

Agronomic plant species may display physiological and biochemical responses to oxidative stress caused by heavy metals and metalloids. Zea mays plants were grown hydroponically for eight days at different concentrations of As (0, 134 and 668 μM) and at different pH (4, 7 and 9). Metabolic variations in response to As toxicity were measured using physiological parameters and antioxidant enzymatic activities. A significant decrease in SOD activity was observed in the leaves and roots of Z. mays with the majority of As treatments. As decreased G-POX activity less in leaves than in roots. An increase in the concentration of As increased APX activity in leaves and roots, except As(V) at pH 4 and pH 9 in the leaves and As(III) at pH 9 in the roots, when there was a significant decrease in APX activity at low As concentrations. After exposure to As(V), CAT activity was the same as in the control. As(III) led to an increase in CAT activity in leaves and to a decrease in roots. With increasing concentrations of As(III), CAT activity increased in both leaves and roots whatever the pH. To obtain more detailed knowledge on the effects of arsenate and arsenite exposure on Vicia faba and Z. mays, root meristems were also examined. Roots were fed hydroponically with 134, 334, 534 and 668 μM arsenate or arsenite and 4 × 10(-3)M of maleic hydrazide as positive control, at three different pH. Physiological parameters, the mitotic index and micronuclei frequencies were evaluated in root meristems. At all three pH, the highest As(V) and As(III) concentrations induced a substantial modification in root colour, increased root thickness with stiffening, and reduced root length. High concentrations also caused a significant decrease in the mitotic index, and micronucleus chromosomic aberrations were observed in the root meristems of both species. 2010 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Phytoaccumulation of Heavy Metals in Natural Vegetation at the Municipal Wastewater Site in Abbottabad, Pakistan.

PubMed

Irshad, Muhammad; Ruqia, Bibi; Hussain, Zahid

2015-01-01

Heavy metal accumulation in crops and soils from wastewater irrigation poses a significant threat to the human health. A study was carried out to investigate the removal potential of heavy metals (HM) by native plant species, namely Cannabis sativa L., Chenopodium album L., Datura stramonium L., Sonchus asper L., Amaranthus viridus L., Oenothera rosea (LHer), Xanthium stramonium L., Polygonum macalosa L., Nasturtium officinale L. and Conyza canadensis L. growing at the municipal wastewater site in Abbottabad city, Pakistan. The HM concentrations varied among plants depending on the species. Metal concentrations across species varied in the order iron (Fe) > zinc (Zn) > chromium (Cr) > nickel (Ni) > cadmium (Cd). Majority of the species accumulated more HM in roots than shoots. Among species, the concentrations (both in roots and shoots) were in the order C. sativa > C. album > X. stramonium > C. canadensis > A. viridus > N. officinale > P. macalosa > D. stramonium > S. asper > O. rosea. No species was identified as a hyperaccumulator. All species exhibited a translocation factor (TF) less than 1. Species like C. sativa, C. album and X. stramonium gave higher (> 1) biological concentration factor (BCF) and biological accumulation coefficient (BAC) especially for Fe, Cr and Cd than other species. Higher accumulation of heavy metals in these plant species signifies the general application of these species for phytostabilization and phytoextraction of HM from polluted soils.

Silicon alleviates Cd stress of wheat seedlings (Triticum turgidum L. cv. Claudio) grown in hydroponics.

PubMed

Rizwan, M; Meunier, J-D; Davidian, J-C; Pokrovsky, O S; Bovet, N; Keller, C

2016-01-01

We investigated the potential role of silicon in improving tolerance and decreasing cadmium (Cd) toxicity in durum wheat (Triticum turgidum L. durum) either through a reduced Cd uptake or exclusion/sequestration in non-metabolic tissues. For this, plants were grown in hydroponic conditions for 10 days either in presence or absence of 1 mM Si and for 11 additional days in various Cd concentrations (0, 0.5, 5.0 and 50 μM). After harvesting, morphological and physiological parameters as well as elemental concentrations were recorded. Cadmium caused reduction in growth parameters, photosynthetic pigments and mineral nutrient concentrations both in shoots and roots. Shoot and root contents of malate, citrate and aconitate increased, while contents of phosphate, nitrate and sulphate decreased with increasing Cd concentrations in plants. Addition of Si to the nutrient solution mitigated these adverse effects: Cd concentration in shoots decreased while concentration of Cd adsorbed at the root cell apoplasmic level increased together with Zn uptake by roots. Overall, total Cd uptake decreased in presence of Si. There was no co-localisation of Cd and Si either at the shoot or at the root levels. No Cd was detected in leaf phytoliths. In roots, Cd was mainly detected in the cortical parenchyma and Si at the endodermis level, while analysis of the outer thin root surface of the plants grown in the 50 μM Cd + 1 mM Si treatment highlighted non-homogeneous Cd and Si enrichments. These data strongly suggest the existence of a root localised protection mechanism consisting in armoring the root surface by Si- and Cd-bearing compounds and in limiting root-shoot translocation.

Can Cd translocation in Oryza sativa L. be attenuated by arbuscular mycorrhizal fungi in the presence of EDTA?

PubMed

Huang, Xiaochen; An, Guangnan; Zhu, Shishu; Wang, Li; Ma, Fang

2018-04-01

Arbuscular mycorrhizal (AM) fungi play an important role in plant tolerance of heavy metal contamination. In this study, a pot experiment was conducted to illustrate the effects of the two AM fungi species Funneliformis mosseae (Fm) and Rhizophagus irregularis (Ri) on plant growth of Oryza sativa L. either with or without ethylenediamine tetraacetate (EDTA) addition and during exposure to five Cd concentrations (in the range of 0-5 mg kg -1 ). The results showed that Fm inoculation achieved greater mycorrhizal colonization and mycorrhizal dependency indexes than Ri inoculation. In addition, the effects of AM fungi on Cd biosorption and translocation in rice were also investigated in the presence of EDTA. Despite cooperative adsorption, the Freundlich isotherm could describe the biosorption effects of Cd on rice roots regardless of AM fungi inoculation or EDTA addition. Cd concentrations in mycorrhizal roots increased but decreased in mycorrhizal shoots in contrast to the control treatment. Although EDTA addition negatively inhibited the uptake of Cd to mycorrhizal shoots, lower translocation factor (TF) and bioconcentration factor (BCF) were still observed in treatments with EDTA compared to control treatment. Our findings suggest that Ri and Fm inoculation enhanced Cd immobilization in the roots, thus preventing Cd entry into the food chain during exposure to low and high Cd stress, respectively.

Effects of phosphorus supply on growth, phosphate concentration and cluster-root formation in three Lupinus species

PubMed Central

Abdolzadeh, Ahmad; Wang, Xing; Veneklaas, Erik J.; Lambers, Hans

2010-01-01

Background and Aims In some lupin species, phosphate deficiency induces cluster-root formation, which enhances P uptake by increasing root surface area and, more importantly, the release of root exudates which enhances P availability. Methods Three species of Lupinus, L. albus, L. atlanticus and L. micranthus, with inherently different relative growth rates were cultivated under hydroponics in a greenhouse at four phosphate concentrations (1, 10, 50 and 150 µm) to compare the role of internal P in regulating cluster-root formation. Key Results The highest growth rate was observed in L. atlanticus, followed by L. albus and L. micranthus. At 1 µm P, cluster-root formation was markedly induced in all three species. The highest P uptake and accumulation was observed in L. micranthus, followed by L. atlanticus and then L. albus. Inhibition of cluster-root formation was severe at 10 µm P in L. atlanticus, but occurred stepwise with increasing P concentration in the root medium in L. albus. Conclusions In L. atlanticus and L. albus cluster-root formation was suppressed by P treatments above 10 µm, indicating a P-inducible regulating system for cluster-root formation, as expected. By contrast, production of cluster roots in L. micranthus, in spite of a high internal P concentration, indicated a lower sensitivity to P status, which allowed P-toxicity symptoms to develop. PMID:20037142

[Study on teratogenic effect of potassium dichromate on Vicia faba root tip cells].

PubMed

Qian, Xiao-Wei

2004-05-01

We studied the aberrant effects of different concentrations of potassium dichromate on Vicia faba root tip cells. The micronucleus and chromosome aberration assay was conducted to determine the micronucleus rate and chromosome aberration rate of Vicia faba root tip cells induced by potassium dichromate. The result indicated that potassium dichromate could increase the micronucleus rate of Vicia faba root tip cells. Within certain range of concentration the rate of micronucleus was found to be increased with the increase of potassium dichromate concentration,but beyond this range the rate of micronucleus decreased with further increase of potassium dichromate concentration. The potassium dichromate at different concentrations could increase the cell mitosis index. Besides,it also caused various types of chromosome aberration,and the rates of chromosome aberration were always higher than that of the control group. The conclusion of this study was that potassium dichromate has obvious teratogenic effect on Vicia faba root tip cells.

Contamination of polycyclic aromatic hydrocarbons (PAHs) in surface sediments and plants of mangrove swamps in Shenzhen, China.

PubMed

Li, Fenglan; Zeng, Xiaokang; Yang, Junda; Zhou, Kai; Zan, Qijie; Lei, Anping; Tam, Nora F Y

2014-08-30

The concentrations of 16 individual and total polycyclic aromatic hydrocarbons (∑PAHs) in sediments, roots and leaves of three mangrove swamps in Shenzhen, China, namely Futian, Baguang and Waterlands, were determined. The mean concentration of ∑PAHs in Futian (4480 ng g(-1)) was significantly higher than that in Baguang (1262 ng g(-1)) and Waterlands (2711 ng g(-1)). Among the 16 PAHs, the concentration of naphthalene was the highest. Based on the ratios of phenanthrene/anthracene and fluoranthene/pyrene, PAHs in Futian and Waterlands came from petrogenic and pyrolytic sources, while Baguang was mainly from pyrolytic. More PAHs were accumulated in leaves, as reflected by its higher mean concentration of ∑PAHs (3697 ng g(-1)) and bioconcentration factor of PAHs (BCF) (>1.5) than that in roots. The BCF values in plants collected from Futian were significantly higher than that from Waterlands. These results indicated that more attention should be paid to the PAH contamination in Futian. Copyright © 2014 Elsevier Ltd. All rights reserved.

Potential of Melastoma malabathricum as bio-accumulator for uranium and thorium from soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saat, Ahmad, E-mail: ahmad183@salam.uitm.edu.my; Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam; Kamsani, Ain Shaqina

2015-04-29

Uranium and Thorium are naturally occuring radionuclides. However, due to anthropogenic activities in some locations their concentrations in the soils could be elevated. This study explores the potential of Melastoma malabathricum (locally known as ‘pokok senduduk’) as bio-accumulator of uranium and thorium from soils of three different study areas, namely former tin mining, industrial and residential/commercial areas in Peninsular Malaysia. The study found elevated concentrations of uranium and thorium in former tin mining soils as compared to natural abundance. However in industral and residential/commercial areas the concentrations are within the range of natural abundance. In terms of transfer factor (TF),more » in ex-mining areas TF > 1 for uranium in the leaf, stem and roots, indicating accumulation of uranium from soil. However for thorium TF < 1, indicating the occurence of transfer from soil to root, stem and leaf, but no accumulation. For other areas only transfer of uranium and thorium were observed. The results indicated the potential of Melastoma malabathricum to be used as bio-accumulatior of uranium, especially in areas of elevated concentration.« less

The Effects of High Steady State Auxin Levels on Root Cell Elongation in Brachypodium[OPEN

PubMed Central

Pacheco-Villalobos, David; Tamaki, Takayuki; Gujas, Bojan; Jaspert, Nina; Oecking, Claudia; Bulone, Vincent; Hardtke, Christian S.

2016-01-01

The long-standing Acid Growth Theory of plant cell elongation posits that auxin promotes cell elongation by stimulating cell wall acidification and thus expansin action. To date, the paucity of pertinent genetic materials has precluded thorough analysis of the importance of this concept in roots. The recent isolation of mutants of the model grass species Brachypodium distachyon with dramatically enhanced root cell elongation due to increased cellular auxin levels has allowed us to address this question. We found that the primary transcriptomic effect associated with elevated steady state auxin concentration in elongating root cells is upregulation of cell wall remodeling factors, notably expansins, while plant hormone signaling pathways maintain remarkable homeostasis. These changes are specifically accompanied by reduced cell wall arabinogalactan complexity but not by increased proton excretion. On the contrary, we observed a tendency for decreased rather than increased proton extrusion from root elongation zones with higher cellular auxin levels. Moreover, similar to Brachypodium, root cell elongation is, in general, robustly buffered against external pH fluctuation in Arabidopsis thaliana. However, forced acidification through artificial proton pump activation inhibits root cell elongation. Thus, the interplay between auxin, proton pump activation, and expansin action may be more flexible in roots than in shoots. PMID:27169463

Douglas fir (pseudotsuga menziesii) plantlets responses to as, PB, and sb-contaminated soils from former mines.

PubMed

Bonet, Amandine; Pascaud, Grégoire; Faugeron, Céline; Soubrand, Marilyne; Joussein, Emmanuel; Gloaguen, Vincent; Saladin, Gaëlle

2016-01-01

Phytoremediation of metalloids by conifers is not widely studied although they may be relevant for several contaminated sites, especially those located in cold areas and sometimes under dry climates. Here, seeds of Douglas fir were sown in greenhouse on three soils collected in two French former mines: a gold mine (soils L1 and L2) and a lead and silver mine (soil P). These soils are highly contaminated by Pb, As, and Sb at different concentrations. Plants were harvested after ten weeks. Growth parameters, primary metabolite content, and shoot and root ionomes were determined. Douglas firs grown on the soils L1 and P had a lower biomass than controls and a higher oxidation status whereas those grown on the soil L2 exhibited a more developed root system and only slight modifications of carbon and nitrogen nutrition. Based on trace element (TE) concentrations in shoots and roots and their translocation factor (TF), Douglas fir could be a relevant candidate for As phytoextraction (0.8 g. kg(-1) dry weight in shoots and a TF of 1.1) and may be used to phytostabilize Pb and Sb (8.8 g and 127 mg. kg(-1) in roots for Pb and Sb, respectively, and TF lower than 0.1).

Uptake of polybrominated diphenyl ethers by carrot and lettuce crops grown in compost-amended soils.

PubMed

Bizkarguenaga, E; Iparraguirre, A; Oliva, E; Quintana, J B; Rodil, R; Fernández, L A; Zuloaga, O; Prieto, A

2016-02-01

The uptake of polybrominated diphenyl ethers (PBDEs) by carrot and lettuce was investigated. Degradation of PBDEs in soil in the absence of the plants was discarded. Different carrot (Nantesa and Chantenay) and lettuce (Batavia Golden Spring and Summer Queen) varieties were grown in fortified or contaminated compost-amended soil mixtures under greenhouse conditions. After plant harvesting, roots (core and peel) and leaves were analyzed separately for carrot, while for lettuce, leaves and hearts were analyzed together. The corresponding bioconcentration factors (BCFs) were calculated. In carrots, a concentration gradient of 2,2',3,4,4',5'-hexabromodiphenyl ether (BDE-138) became evident that decreased from the root peel via root core to the leaves. For decabromodiphenyl ether (BDE-209) at the low concentration level (7 and 20 ng g(-1)), the leaves incorporated the highest concentration of the target substance. For lettuce, a decrease in the BCF value (from 0.24 to 0.02) was observed the higher the octanol-water partition coefficient, except in the case of BDE-183 (BCF = 0.51) and BDE-209 (BCF values from 0.41 to 0.74). Significant influence of the soils and crop varieties on the uptake could not be supported. Metabolic debromination, hydroxylation or methylation of the target PBDEs in the soil-plant system was not observed.

Brassinolide Increases Potato Root Growth In Vitro in a Dose-Dependent Way and Alleviates Salinity Stress

PubMed Central

Xia, Shitou; Su, Yi; Wang, Huiqun; Luo, Weigui; Su, Shengying

2016-01-01

Brassinosteroids (BRs) are steroidal phytohormones that regulate various physiological processes, such as root development and stress tolerance. In the present study, we showed that brassinolide (BL) affects potato root in vitro growth in a dose-dependent manner. Low BL concentrations (0.1 and 0.01 μg/L) promoted root elongation and lateral root development, whereas high BL concentrations (1–100 μg/L) inhibited root elongation. There was a significant (P < 0.05) positive correlation between root activity and BL concentrations within a range from 0.01 to 100 μg/L, with the peak activity of 8.238 mg TTC·g−1 FW·h−1 at a BL concentration of 100 μg/L. Furthermore, plants treated with 50 μg/L BL showed enhanced salt stress tolerance through in vitro growth. Under this scenario, BL treatment enhanced the proline content and antioxidant enzymes' (superoxide dismutase, peroxidase, and catalase) activity and reduced malondialdehyde content in potato shoots. Application of BL maintain K+ and Na+ homeostasis by improving tissue K+/Na+ ratio. Therefore, we suggested that the effects of BL on root development from stem fragments explants as well as on primary root development are dose-dependent and that BL application alleviates salt stress on potato by improving root activity, root/shoot ratio, and antioxidative capacity in shoots and maintaining K+/Na+ homeostasis in potato shoots and roots. PMID:27803931

Nutrient concentrations within and below root zones from applied chicken manure in selected Hawaiian soils.

PubMed

Ahmad, Amjad A; Fares, Ali; Abbas, Farhat; Deenik, Jonathan L

2009-11-01

The objective of this study was to evaluate the effects of chicken manure (CM) application rates on nutrient concentrations within and below the root zone of sweet corn (Zea mays L. subsp. mays) under Hawaiian conditions. The research was conducted in leeward (Poamoho) and windward (Waimanalo) areas of Oahu, Hawaii, where contrasts exist in both climatic and soil conditions. Suction cup were used to collect soil solutions from 30 and 60 cm depths. Soil solutions were collected six times during the growing season at each location and analyzed for different nutrients (N, P, K, Ca, Mg, Na, Fe, Mn, Zn, and Cu), nitrate-nitrogen (NO(3)-N), ammonium-nitrogen (NH(4)-N), electrical conductivity (EC), and pH. Analysis showed that CM rates significantly affected the concentration of macro-nutrients below the root zone at Poamoho and within the root zone at Waimanalo. In general, nutrient concentration increased with the increasing rates of CM application. There was a significant effect of CM on micro-nutrients except below the root zone at Poamoho. CM significantly affected NO(3)-N concentration within the root zone for 15, 60 days after planting (DAP) at Poamoho, and 16, 28 DAP at Waimanalo. The effect was also significant on total nitrogen (N) concentration in the root zone across the two growing seasons at Waimanalo. There was a highly significant correlation between total N and NO(3)-N, and EC within and below the root zone.

Phytoextraction potential of poplar (Populus alba L. var. pyramidalis Bunge) from calcareous agricultural soils contaminated by cadmium.

PubMed

Hu, Yahu; Nan, Zhongren; Jin, Cheng; Wang, Ning; Luo, Huanzhang

2014-01-01

To investigate the phytoextraction potential of Populus alba L. var. pyramidalis Bunge for cadmium (Cd) contaminated calcareous soils, a concentration gradient experiment and a field sampling experiment (involving poplars of different ages) were conducted. The translocation factors for all experiments and treatments were greater than 1. The bioconcentration factor decreased from 2.37 to 0.25 with increasing soil Cd concentration in the concentration gradient experiment and generally decreased with stand age under field conditions. The Cd concentrations in P. pyramidalis organs decreased in the order of leaves > stems > roots. The shoot biomass production in the concentration gradient experiment was not significantly reduced with soil Cd concentrations up to or slightly over 50 mg kg(-1). The results show that the phytoextraction efficiency of P. pyramidalis depends on both the soil Cd concentration and the tree age. Populus pyramidalis is most suitable for remediation of slightly Cd contaminated calcareous soils through the combined harvest of stems and leaves under actual field conditions.

Bioavailable concentrations of germanium and rare earth elements in soil as affected by low molecular weight organic acids and root exudates

NASA Astrophysics Data System (ADS)

Wiche, Oliver; Székely, Balázs; Kummer, Nicolai-Alexeji; Heinemann, Ute; Tesch, Silke; Heilmeier, Hermann

2014-05-01

Availability of elements in soil to plant is generally dependent on the solubility and mobility of elements in soil solution which is controlled by soil, elemental properties and plant-soil interactions. Low molecular organic acids or other root exudates may increase mobility and availability of certain elements for plants as an effect of lowering pH in the rhizosphere and complexation. However, these processes take place in a larger volume in soil, therefore to understand their nature, it is also important to know in which layers of the soil what factors modify these processes. In this work the influence of citric acid and root exudates of white lupin (Lupinus albus L.) on bioavailable concentrations of germanium, lanthan, neodymium, gadolinium and erbium in soil solution and uptake in root and shoot of rape (Brassica napus L.), comfrey (Symphytum officinale L.), common millet (Panicum milliaceum L.) and oat (Avena sativa L.) was investigated. Two different pot experiments were conducted: (1) the mentioned plant species were treated with nutrient solutions containing various amount of citric acid; (2) white lupin was cultivated in mixed culture (0 % lupin, 33 % lupin) with oat (Avena sativa L.) and soil solution was obtained by plastic suction cups placed at various depths. As a result, addition of citric acid significantly increased germanium concentrations in plant tissue of comfrey and rape and increased translocation of germanium, lanthan, neodymium, gadolinium and erbium from root to shoot. The cultivation of white lupin in mixed culture with oat led to significantly higher concentrations of germanium and increasing concentrations of lanthan, neodymium, gadolinium and erbium in soil solution and aboveground plant tissue. In these pots concentrations of citric acid in soil solution were significantly higher than in the control. The results show, that low molecular organic acids exuded by plant roots are of great importance for the mobilization of germanium, lanthan, neodymium, gadolinium and erbium in the rhizosphere and therefore the enhancement of bioavailability of the mentioned elements to plants. Based on the suction cup experiment we conclude that in vertical soil profile the bioavailable germanium is heavily affected by the activity of exudates, as the complexation processes of germanium take place at the root zone and below affected by the interplay of the infiltration of citric acid solutions and the actually produced exudates. These studies have been carried out in the framework of the PhytoGerm project, financed by the Federal Ministry of Education and Research, Germany. BS contributed as an Alexander von Humboldt Research Fellow. The authors are grateful to students and laboratory assistants contributing in the field work and sample preparation.

Estimation of the Potential for Atrazine Transport in a Silt Loam Soil

USGS Publications Warehouse

Eckhardt, D.A.V.; Wagenet, R.J.

1996-01-01

The transport potential of the herbicide atrazine (2-chloro-4-ethyl-6-isopropyl-s-triazine) through a 1-meter-thick root zone of corn (Zea mays L.) in a silty-loam soil in Kansas was estimated for a 22-year period (1972-93) using the one-dimensional water-flow and solute-transport model LEACHM. Results demonstrate that, for this soil, atrazine transport is directly related to the amount and timing of rain that follows spring applications of atrazine. Two other critical transport factors were important in wet years - [1] variability in atrazine application rate, and [2] atrazine degradation rates below the root zone. Results demonstrate that the coincidence of heavy rain soon after atrazine application can cause herbicide to move below the rooting zone into depths at which biodegradation rates are assumed to be low but are often unknown. Atrazine that reaches below the rooting zone and persists in the underlying soil can subsequently be transported into ground water as soil water drains, typically after the growing season. A frequency analysis of atrazine concentrations in subsurface drainage, combined with field data, demonstrates the relative importance of critical transport factors and confirms a need for definitive estimates of atrazine-degradation rates below the root zone. The analysis indicates that periodic leaching of atrazine can be expected for this soil when rainfall that exceeds 20 cm/mo coincides with atrazine presence in soil.

Auxin, the organizer of the hormonal/environmental signals for root hair growth

PubMed Central

Lee, Richard D.-W.; Cho, Hyung-Taeg

2013-01-01

The root hair development is controlled by diverse factors such as fate-determining developmental cues, auxin-related environmental factors, and hormones. In particular, the soil environmental factors are important as they maximize their absorption by modulating root hair development. These environmental factors affect the root hair developmental process by making use of diverse hormones. These hormonal factors interact with each other to modulate root hair development in which auxin appears to form the most intensive networks with the pathways from environmental factors and hormones. Moreover, auxin action for root hair development is genetically located immediately upstream of the root hair-morphogenetic genes. These observations suggest that auxin plays as an organizing node for environmental/hormonal pathways to modulate root hair growth. PMID:24273547

Exogenous nitrate induces root branching and inhibits primary root growth in Capsicum chinense Jacq.

PubMed

Celis-Arámburo, Teresita de Jesús; Carrillo-Pech, Mildred; Castro-Concha, Lizbeth A; Miranda-Ham, María de Lourdes; Martínez-Estévez, Manuel; Echevarría-Machado, Ileana

2011-12-01

The effects of nitrate (NO₃⁻) on the root system are complex and depend on several factors, such as the concentration available to the plant, endogenous nitrogen status and the sensitivity of the species. Though these effects have been widely documented on Arabidopsis and cereals, no reports are available in the Capsicum genus. In this paper, we have determined the effect of an exogenous in vitro application of this nutrient on root growth in habanero pepper (Capsicum chinense Jacq.). Exposure to NO₃⁻ inhibited primary root growth in both, dose- and time-dependent manners. The highest inhibition was attained with 0.1 mM NO₃⁻ between the fourth and fifth days of treatment. Inhibition of primary root growth was observed by exposing the root to both homogeneous and heterogeneous conditions of the nutrient; in contrast, ammonium was not able to induce similar changes. NO₃⁻-induced inhibition of primary root growth was reversed by treating the roots with IAA or NPA, a polar auxin transport inhibitor. Heterogeneous NO₃⁻ application stimulated the formation and elongation of lateral roots in the segment where the nutrient was present, and this response was influenced by exogenous phytohormones. These results demonstrate that habanero pepper responds to NO₃⁻ in a similar fashion to other species with certain particular differences. Therefore, studies in this model could help to elucidate the mechanisms by which roots respond to NO₃⁻ in fluctuating soil environments. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Experimentally reduced root-microbe interactions reveal limited plasticity in functional root traits in Acer and Quercus.

PubMed

Lee, Mei-Ho; Comas, Louise H; Callahan, Hilary S

2014-02-01

Interactions between roots and soil microbes are critical components of below-ground ecology. It is essential to quantify the magnitude of root trait variation both among and within species, including variation due to plasticity. In addition to contextualizing the magnitude of plasticity relative to differences between species, studies of plasticity can ascertain if plasticity is predictable and whether an environmental factor elicits changes in traits that are functionally advantageous. To compare functional traits and trait plasticities in fine root tissues with natural and reduced levels of colonization by microbial symbionts, trimmed and surface-sterilized root segments of 2-year-old Acer rubrum and Quercus rubra seedlings were manipulated. Segments were then replanted into satellite pots filled with control or heat-treated soil, both originally derived from a natural forest. Mycorrhizal colonization was near zero in roots grown in heat-treated soil; roots grown in control soil matched the higher colonization levels observed in unmanipulated root samples collected from field locations. Between-treatment comparisons revealed negligible plasticity for root diameter, branching intensity and nitrogen concentration across both species. Roots from treated soils had decreased tissue density (approx. 10-20 %) and increased specific root length (approx. 10-30 %). In contrast, species differences were significant and greater than treatment effects in traits other than tissue density. Interspecific trait differences were also significant in field samples, which generally resembled greenhouse samples. The combination of experimental and field approaches was useful for contextualizing trait plasticity in comparison with inter- and intra-specific trait variation. Findings that root traits are largely species dependent, with the exception of root tissue density, are discussed in the context of current literature on root trait variation, interactions with symbionts and recent progress in standardization of methods for quantifying root traits.

Respiration rate in maize roots is related to concentration of reduced nitrogen and proliferation of lateral roots

NASA Technical Reports Server (NTRS)

Granato, T. C.; Raper, C. D. Jr; Wilkerson, G. G.; Raper CD, J. r. (Principal Investigator)

1989-01-01

The relationship between specific rate of respiration (respiration rate per unit root dry weight) and concentration of reduced nitrogen was examined for maize (Zea mays L.) roots. Plants with 2 primary nodal root axes were grown for 8 days in a split-root hydroponic system in which NO3- was supplied to both axes at 1.0 mol m-3, to one axis at 1.0 mol m-3 and the other axis at 0.0 mol m-3, or to both axes at 0.0 mol m-3. Respiration rates and root characteristics were measured at 2-day intervals. Specific rate of respiration was positively correlated in a nonlinear relationship with concentration of reduced nitrogen. The lowest specific rates of respiration occurred when neither axis received exogenous NO3- and the concentration of reduced nitrogen in the axes was less than 9 mg g-1. The greatest rates occurred in axes that were actively absorbing NO3- and contained more than 35 mg g-1 of reduced nitrogen. At 23 mg g-1 of reduced nitrogen, below which initiation of lateral branches was decreased by 30-50%, specific rate of respiration was 17% greater for roots actively absorbing NO3- than for roots not absorbing NO3-. Increases in specific rate of respiration associated with concentrations of reduced nitrogen greater than 23 mg g-1 were concluded to be attributable primarily to proliferation of lateral branches.

Effect of soil water content on spatial distribution of root exudates and mucilage in the rhizosphere

NASA Astrophysics Data System (ADS)

Holz, Maire; Zarebanadkouki, Mohsen; Kuzyakov, Yakov; Carminati, Andrea

2016-04-01

Water and nutrients are expected to become the major factors limiting food production. Plant roots employ various mechanisms to increase the access to these limited soil resources. Low molecular root exudates released into the rhizosphere increase nutrient availability, while mucilage improves water availability under low moisture conditions. However, studies on the spatial distribution and quantification of exudates in soil are scarce. Our aim was therefore to quantify and visualize root exudates and mucilage distribution around growing roots using neutron radiography and 14C imaging at different levels of water stress. Maize plants were grown in rhizotrons filled with a silty soil and were exposed to varying soil conditions, from optimal to dry. Mucilage distribution around the roots was estimated from the profiles of water content in the rhizosphere - note that mucilage increases the soil water content. The profiles of water content around different root types and root ages were measured with neutron radiography. Rhizosphere extension was approx. 0.7 mm and did not differ between wet and dry treatments. However, water content (i.e. mucilage concentration) in the rhizosphere of plants grown in dry soils was higher than for plants grown under optimal conditions. This effect was particularly pronounced near the tips of lateral roots. The higher water contents near the root are explained as the water retained by mucilage. 14C imaging of root after 14CO2 labeling of shoots (Pausch and Kuzyakov 2011) was used to estimate the distribution of all rhizodeposits. Two days after labelling, 14C distribution was measured using phosphor-imaging. To quantify 14C in the rhizosphere a calibration was carried out by adding given amounts of 14C-glucose to soil. Plants grown in wet soil transported a higher percentage of 14C to the roots (14Croot/14Cshoot), compared to plants grown under dry conditions (46 vs. 36 %). However, the percentage of 14C allocated from roots to rhizosphere (14Crhizosphere/14Croot) was double in plants grown under dry conditions (0.43 vs. 0.75 %). Plants grown in wet soils showed a faster root growth (1.4 cm d-1) compared to plants in dry soil (1 cm d-1). Compared to the results with neutron radiography, rhizosphere extension of 14C was generally higher and strongly depended on root type: it was 2 mm for main roots and 1 mm for lateral roots. This indicates that low molecular exudates diffuse further into the soil than mucilage. As for mucilage, concentration of 14C was higher in the rhizosphere of plants grown under dry conditions. This observation can be explained by: (a) higher allocation of 14C from roots to rhizosphere in dry soils, (b) a fast diffusion of exudates in wet soils, and (c) faster root growth in wet soils, which results in lower exudation per root length. In summary, the combination of neutron radiography and 14C imaging was successfully used to visualize and to quantify the distribution of mucilage and root exudates in the rhizosphere of plants grown in soil. The high concentration of root exudates in rhizosphere under dry conditions might be strategy of plants to increase their water and nutrient availability unfavorable conditions.

Root respiration in North American forests: Effects of nitrogen concentration and temperature across biomes

Treesearch

A.J. Burton; K.S. Pregitzer; R.W. Ruess; R.L. Hendrick; Mike F. Allen

2002-01-01

Root respiration rates have been shown to be correlated with temperature and root N concentration in studies of individual forest types or species, but it is not known how universal these relationships are across forest species adapted to widely different climatic and edaphic conditions. In order to test for broad, cross-species relationships, we measured fine root...

Fermentation of Smilax china root by Aspergillus usami and Saccharomyces cerevisiae promoted concentration of resveratrol and oxyresveratrol and the free-radical scavenging activity.

PubMed

Yoon, So-Ra; Yang, Seung-Hwan; Suh, Joo-Won; Shim, Soon-Mi

2014-07-01

Smilax china root, which is rich in resveratrol and oxyresveratrol, has been used as emergency foods as well as folk medicine. This study investigated changes in concentration of bioactive components and the free-radical scavenging capacity of Smilax china root during fermentation by Aspergillus usami and Saccharomyces cerevisiae. Resveratrol, oxyresveratrol and piceid were quantified as major constituents in Smilax china root by using UPLC-ESI-MS. The concentration of oxyresveratrol and resveratrol remarkably increased through fermentation and the transformation of piceid to resveratrol. Its concentration in 4% Smilax china root was 1.16-2.95 times higher than that of a 2% preparation throughout fermentation. The vitamin C equivalent antioxidant capacity of 2% Smilax china root was 1.51-1.91 times higher than that of 4% Smilax china root during fermentation. Meanwhile, ABTS free-radical scavenging capacity was enhanced up to 95.07 and 99.35% for 2% and 4% Smilax china root, respectively. Results from our study propose that bioactive components in Smilax China root were highly extracted by fermentation followed by saccharification and ethanol production, resulting in enhanced free-radical scavenging capacity. © 2013 Society of Chemical Industry. © 2013 Society of Chemical Industry.

The promotive effect of latrunculin B on maize root gravitropism is concentration dependent

NASA Technical Reports Server (NTRS)

Blancaflor, E. B.; Hou, G-C; Mohamalawari, D. R.

2003-01-01

The cytoskeleton has been proposed to be a key player in the gravitropic response of higher plants. A major approach to determine the role of the cytoskeleton in gravitropism has been to use inhibitors to disrupt the cytoskeleton and then to observe the effect that such disruption has on organ bending. Several investigators have reported that actin or microtubule inhibitors do not prevent root gravitropism, leading to the conclusion that the cytoskeleton is not involved in this process. However, there are recent reports showing that disruption of the actin cytoskeleton with the actin inhibitor, latrunculin B, promotes the gravitropic response of both roots and shoots. In roots, curvature is sustained during prolonged periods of clinorotation despite short periods of gravistimulation. These results indicate that an early gravity-induced signal continues to persist despite withdrawal of the constant gravity stimulus. To investigate further the mechanisms underlying the promotive effect of actin disruption on root gravitropism, we treated maize roots with varying concentrations of latrunculin B in order to determine the lowest concentration of latrunculin B that has an effect on root bending. After a 10-minute gravistimulus, treated roots were axially rotated on a one rpm clinostat and curvature was measured after 15 hours. Our results show that 100 nM latrunculin B induced the strongest promotive effect on the curvature of maize roots grown on a clinostat. Moreover, continuously gravistimulated roots treated with 100 nM latrunculin B exhibited stronger curvature responses while decapped roots treated with this concentration of latrunculin B did not bend during continuous gravistimulation. The stronger promotive effect of low concentrations of latrunculin B on the curvature of both clinorotated and continuously gravistimulated roots suggests that disruption of the finer, more dynamic component of the actin cytoskeleton could be the cause of the enhanced tropic responses of roots to gravity. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

The promotive effect of latrunculin B on maize root gravitropism is concentration dependent

NASA Astrophysics Data System (ADS)

Blancaflor, E. B.; Hou, G.-c.; Mohamalawari, D. R.

2003-05-01

The cytoskeleton has been proposed to be a key player in the gravitropic response of higher plants. A major approach to determine the role of the cytoskeleton in gravitropism has been to use inhibitors to disrupt the cytoskeleton and then to observe the effect that such disruption has on organ bending. Several investigators have reported that actin or microtubule inhibitors do not prevent root gravitropism, leading to the conclusion that the cytoskeleton is not involved in this process. However, there are recent reports showing that disruption of the actin cytoskeleton with the actin inhibitor, latrunculin B, promotes the gravitropic response of both roots and shoots. In roots, curvature is sustained during prolonged periods of clinorotation despite short periods of gravistimulation. These results indicate that an early gravity-induced signal continues to persist despite withdrawal of the constant gravity stimulus. To investigate further the mechanisms underlying the promotive effect of actin disruption on root gravitropism, we treated maize roots with varying concentrations of latrunculin B in order to determine the lowest concentration of latrunculin B that has an effect on root bending. After a 10-minute gravistimulus, treated roots were axially rotated on a one rpm clinostat and curvature was measured after 15 hours. Our results show that 100 nM latrunculin B induced the strongest promotive effect on the curvature of maize roots grown on a clinostat. Moreover, continuously gravistimulated roots treated with 100 nM latrunculin B exhibited stronger curvature responses while decapped roots treated with this concentration of latrunculin B did not bend during continuous gravistimulation. The stronger promotive effect of low concentrations of latrunculin B on the curvature of both clinorotated and continuously gravistimulated roots suggests that disruption of the fmer, more dynamic component of the actin cytoskeleton could be the cause of the enhanced tropic responses of roots to gravity.

Improving agronomic water use efficiency in tomato by rootstock-mediated hormonal regulation of leaf biomass.

PubMed

Cantero-Navarro, Elena; Romero-Aranda, Remedios; Fernández-Muñoz, Rafael; Martínez-Andújar, Cristina; Pérez-Alfocea, Francisco; Albacete, Alfonso

2016-10-01

Water availability is the most important factor limiting food production, thus developing new scientific strategies to allow crops to more efficiently use water could be crucial in a world with a growing population. Tomato is a highly water consuming crop and improving its water use efficiency (WUE) implies positive economic and environmental effects. This work aimed to study and exploit root-derived hormonal traits to improve WUE in tomato by grafting on selected rootstocks. Firstly, root-related hormonal parameters associated to WUE were identified in a population of recombinant inbred lines (RILs) derived from the wild tomato species Solanum pimpinellifolium. A principal component analysis (PCA) revealed that some hormonal traits were associated with productivity (plant biomass and photosynthesis) and WUE in the RIL population. Leaf ABA concentration was associated to the first component (PC1) of the PCA, which explained a 60% of the variance in WUE, while the ethylene precursor ACC and the ratio ACC/ABA were also associated to PC1 but in the opposite direction. Secondly, we selected RILs according to their extreme biomass (high, B, low, b) and water use (high, W, low, w), and studied the differential effect of shoot and root on WUE by reciprocal grafting. In absence of any imposed stress, there were no rootstock effects on vegetative shoot growth and water relations. Finally, we exploited the previously identified root-related hormonal traits by grafting a commercial tomato variety onto the selected RILs to improve WUE. Interestingly, rootstocks that induced low biomass and water use, 'bw', improved fruit yield and WUE (defined as fruit yield/water use) by up to 40% compared to self-grafted plants. Although other hormonal factors appear implicated in this response, xylem ACC concentration seems an important root-derived trait that inhibits leaf growth but does not limit fruit yield. Thus tomato WUE can be improved exploiting rootstock-derived hormonal signals which control leaf growth. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

The effect of the symbiosis between Tagetes erecta L. (marigold) and Glomus intraradices in the uptake of Copper(II) and its implications for phytoremediation.

PubMed

Castillo, O S; Dasgupta-Schubert, N; Alvarado, C J; Zaragoza, E M; Villegas, H J

2011-12-15

Phytoremediation is an environmental biotechnology that seeks to remediate pollution caused by bioaccumulative toxins like copper (Cu). Symbiotic mycorrhizal associations can increase the uptake and delivery of low mobility nutrients and micronutrients to the host plant because they solubilize these substances and increase their catchment area. To analyze the effect of mycorrhizae on the phytoaccumulation of Cu, we studied their ability to solubilize Cu(II) and enhance its absorption by the plant Tagetes erecta L. colonized with the arbuscular mycorrhizal fungus Glomus intraradices. Plants were grown for nine weeks in a growth chamber under controlled conditions of temperature, relative humidity and photoperiod. Cu was added in the insoluble form of CuO to simulate the insoluble Cu-O affixed species in soil. The biotic and abiotic parameters of colonization, foliar area, biomass and the pH of leachates were determined as functions of the Cu concentration that was measured in the roots, shoots and leachates by AAS. The results of Cu absorption showed that the colonized plants accumulated more Cu in the roots as well as the whole plant and that both the colonized and non-colonized plants displayed the typical behavior of Cu excluders. Mycorrhizal colonization of the roots resulted in a proliferation of vesicles and this was observed to scale with root tissue Cu concentrations. Also, the G. intraradices-T. erecta system displayed a higher resistance to the toxicity induced by Cu while nonetheless improving the indices of phytoaccumulative yields. These results suggest that G. intraradices possibly accumulates Cu in its vesicles thereby enhancing the Cu tolerance of T. erecta even while increasing root Cu accumulation. The parameters of bioconcentration factor and translocation factor measured in this work suggest that the system T. erecta-G. intraradices can potentially phytostabilize Cu in contaminated soils. Copyright © 2011 Elsevier B.V. All rights reserved.

Resistance Responses of Potato to Vesicular-Arbuscular Mycorrhizal Fungi under Varying Abiotic Phosphorus Levels.

PubMed

McArthur, D A; Knowles, N R

1992-09-01

In mycorrhizal symbioses, susceptibility of a host plant to infection by fungi is influenced by environmental factors, especially the availability of soil phosphorus. This study describes morphological and biochemical details of interactions between a vesicular-arbuscular mycorrhizal (VAM) fungus and potato (Solanum tuberosum L. cv Russet Burbank) plants, with a particular focus on the physiological basis for P-induced resistance of roots to infection. Root infection by the VAM fungus Glomus fasciculatum ([Thaxt. sensu Gerdemann] Gerdemann and Trappe) was extensive for plants grown with low abiotic P supply, and plant biomass accumulation was enhanced by the symbiosis. The capacity of excised roots from P-deficient plants to produce ethylene in the presence or absence of exogenous 1-amino cyclopropane-1-carboxylic acid (ACC) was markedly reduced by VAM infection. This apparent inhibition of ACC oxidase (ACC(ox)) activity was localized to areas containing infected roots, as demonstrated in split-root studies. Furthermore, leachate from VAM roots contained a potent water-soluble inhibitor of ethylene generation from exogenous ACC by nonmycorrhizal (NM) roots. The leachate from VAM-infected roots had a higher concentration of phenolics, relative to that from NM roots. Moreover, the rates of ethylene formation and phenolic concentration in leachates from VAM roots were inversely correlated, suggesting that this inhibitor may be of a phenolic nature. The specific activity of extracellular peroxidase recovered in root leachates was not stimulated by VAM infection, although activity on a fresh weight basis was significantly enhanced, reflecting the fact that VAM roots had higher protein content than NM roots. Polyphenol oxidase activity of roots did not differ between NM and VAM roots. These results characterize the low resistance response of P-deficient plants to VAM infection. When plants were grown with higher abiotic P supply, the relative benefit of the VAM symbiosis to plant growth decreased and root infection was lower. The in vivo ACC(ox) activity was also greater in roots of plants grown on high levels of P compared with those grown on low levels, although the influence of VAM infection was partially to counteract the nutritional effect of P on ACC(ox) activity. Similar to ACC(ox) activity, extracellular peroxidase activity of roots increased linearly with increasing abiotic P supply, thus indicating a greater potential for resistance to VAM infection. These findings suggest that VAM fungi may alter phenolic metabolism of roots so as to hinder ethylene production and the root's ability to invoke a defense response. Raising the abiotic P supply to plants at least partially restores the capacity of roots to produce ethylene and may, in this way, increase the root's resistance to VAM infection.

Resistance Responses of Potato to Vesicular-Arbuscular Mycorrhizal Fungi under Varying Abiotic Phosphorus Levels 1

PubMed Central

McArthur, David A. J.; Knowles, N. Richard

1992-01-01

In mycorrhizal symbioses, susceptibility of a host plant to infection by fungi is influenced by environmental factors, especially the availability of soil phosphorus. This study describes morphological and biochemical details of interactions between a vesicular-arbuscular mycorrhizal (VAM) fungus and potato (Solanum tuberosum L. cv Russet Burbank) plants, with a particular focus on the physiological basis for P-induced resistance of roots to infection. Root infection by the VAM fungus Glomus fasciculatum ([Thaxt. sensu Gerdemann] Gerdemann and Trappe) was extensive for plants grown with low abiotic P supply, and plant biomass accumulation was enhanced by the symbiosis. The capacity of excised roots from P-deficient plants to produce ethylene in the presence or absence of exogenous 1-amino cyclopropane-1-carboxylic acid (ACC) was markedly reduced by VAM infection. This apparent inhibition of ACC oxidase (ACCox) activity was localized to areas containing infected roots, as demonstrated in split-root studies. Furthermore, leachate from VAM roots contained a potent water-soluble inhibitor of ethylene generation from exogenous ACC by nonmycorrhizal (NM) roots. The leachate from VAM-infected roots had a higher concentration of phenolics, relative to that from NM roots. Moreover, the rates of ethylene formation and phenolic concentration in leachates from VAM roots were inversely correlated, suggesting that this inhibitor may be of a phenolic nature. The specific activity of extracellular peroxidase recovered in root leachates was not stimulated by VAM infection, although activity on a fresh weight basis was significantly enhanced, reflecting the fact that VAM roots had higher protein content than NM roots. Polyphenol oxidase activity of roots did not differ between NM and VAM roots. These results characterize the low resistance response of P-deficient plants to VAM infection. When plants were grown with higher abiotic P supply, the relative benefit of the VAM symbiosis to plant growth decreased and root infection was lower. The in vivo ACCox activity was also greater in roots of plants grown on high levels of P compared with those grown on low levels, although the influence of VAM infection was partially to counteract the nutritional effect of P on ACCox activity. Similar to ACCox activity, extracellular peroxidase activity of roots increased linearly with increasing abiotic P supply, thus indicating a greater potential for resistance to VAM infection. These findings suggest that VAM fungi may alter phenolic metabolism of roots so as to hinder ethylene production and the root's ability to invoke a defense response. Raising the abiotic P supply to plants at least partially restores the capacity of roots to produce ethylene and may, in this way, increase the root's resistance to VAM infection. Images Figure 1 PMID:16652967

Evolutionary potential of root chemical defense: genetic correlations with shoot chemistry and plant growth.

PubMed

Parker, J D; Salminen, J-P; Agrawal, Anurag A

2012-08-01

Root herbivores can affect plant fitness, and roots often contain the same secondary metabolites that act as defenses in shoots, but the ecology and evolution of root chemical defense have been little investigated. Here, we investigated genetic variance, heritability, and correlations among defensive phenolic compounds in shoot vs. root tissues of common evening primrose, Oenothera biennis. Across 20 genotypes, there were roughly similar concentrations of total phenolics in shoots vs. roots, but the allocation of particular phenolics to shoots vs. roots varied along a continuum of genotype growth rate. Slow-growing genotypes allocated 2-fold more of the potential pro-oxidant oenothein B to shoots than roots, whereas fast-growing genotypes had roughly equivalent above and belowground concentrations. Phenolic concentrations in both roots and shoots were strongly heritable, with mostly positive patterns of genetic covariation. Nonetheless, there was genotype-specific variation in the presence/absence of two major ellagitannins (oenothein A and its precursor oenothein B), indicating two different chemotypes based on alterations in this chemical pathway. Overall, the presence of strong genetic variation in root defenses suggests ample scope for the evolution of these compounds as defenses against root herbivores.

The use of an electric field in increasing the resistance of plants to the action of unfavorable space flight factors

NASA Astrophysics Data System (ADS)

Nechitailo, G.; Gordeev, A.

The key role in increasing the resistance of plants to unfavorable space flight factors is assigned to biomembranes of root cells. It is these biomembranes on which numerous biochemical and biophysical processes determining the adaptive capacity of plant organisms occur. In the initial period of exposure to unfavorable space flight factors the adaptational reactions of the plant organism undoubtedly increase its resistance. But the intensification of removal of H+ ions through the plasmalemma with an increase of the external influence sharply raises the quantity of cations leaving the cell, which leads to the accumu lation of a considerable quantity of intracellular negative charges. These charges together with negative charges built in the membrane force protons to concentrate on the external surface of the membrane. Since protons have a very strong electric field, they form such a charge of which the electric field is about from several to hundreds of V/cm. The concentration of positive charges of protons entails the formation of a double electric field which extremely impedes the diffusion of other ions. Thus, a proton barrier is formed. Its length can be very considerable due to which the whole process of transmembrane energy and mass-transfer is disturbed. The proton barrier is easily destroyed by a weak electric field created in the root zone. In experiment on electrostimulation of different plants under space flight conditions at the orbital station MIR the absorption of nutrient elements by the root system increased to the optimal level, the ratio of physiologically active substances in the rhizosphere was normalized, the content of chlorophyll, carotin, and ascorbic acid in leaves corresponded to the ground-based control. Understanding of the mechanism of formation of a proton barrier on the plasmalemma of root cells as a result of the response of plants to the negative action of external factors (microgravity) is of great importance. It allows the possibility of life support of the vegetable kingdom in extreme conditions to be estimated in a new way.

The use of an electric field in increasing the resistance of plants to the action of unfavorable space flight factors

NASA Astrophysics Data System (ADS)

Nechitailo, G.; Gordeev, A.

2004-01-01

The key role in increasing the resistance of plants to unfavorable space flight factors is assigned to biomembranes of root cells. It is these biomembranes in which numerous biochemical and biophysical processes determining the adaptive capacity of plant organisms occur. In the initial period of exposure to unfavorable space flight factors the adaptation reactions of the plant organism undoubtedly increase its resistance. But the intensification of removal of H + ions through the plasmalemma with an increase of the external influence sharply raises the quantity of cations leaving the cell, which leads to the accumulation of a considerable quantity of intracellular negative charges. These charges together with negative charges built in the membrane force protons to concentrate on the external surface of the membrane. Since protons have a very strong electric field, they form such a charge of which the electric field is about from several to hundreds of V/cm. The concentration of positive charges of protons entails the formation of a double electric field which extremely impedes the diffusion of other ions. Thus, a proton barrier is formed. Its length can be very considerable due to which the whole process of transmembrane energy and mass-transfer is disturbed. The proton barrier is easily destroyed by a weak electric field created in the root zone. In experiments on electrostimulation of different plants under space flight conditions at the orbital station MIR the absorption of nutrient elements by the root system increased to the optimal level, the ratio of physiologically active substances in the rhizosphere was normalized, the content of chlorophyll, carotin, and ascorbic acid in leaves corresponded to the ground-based control. Understanding of the mechanism of formation of a proton barrier on the plasmalemma of root cells as a result of the response of plants to the negative action of external factors (microgravity) is of great importance. It allows the possibility of life support of the vegetable kingdom in extreme conditions to be estimated in a new way.

Evaluation of constitutive iron reductase (AtFRO2) expression on mineral accumulation and distribution in soybean (Glycine max. L)

PubMed Central

Vasconcelos, Marta W.; Clemente, Thomas E.; Grusak, Michael A.

2014-01-01

Iron is an important micronutrient in human and plant nutrition. Adequate iron nutrition during crop production is central for assuring appropriate iron concentrations in the harvestable organs, for human food or animal feed. The whole-plant movement of iron involves several processes, including the reduction of ferric to ferrous iron at several locations throughout the plant, prior to transmembrane trafficking of ferrous iron. In this study, soybean plants that constitutively expressed the AtFRO2 iron reductase gene were analyzed for leaf iron reductase activity, as well as the effect of this transgene’s expression on root, leaf, pod wall, and seed mineral concentrations. High Fe supply, in combination with the constitutive expression of AtFRO2, resulted in significantly higher concentrations of different minerals in roots (K, P, Zn, Ca, Ni, Mg, and Mo), pod walls (Fe, K, P, Cu, and Ni), leaves (Fe, P, Cu, Ca, Ni, and Mg) and seeds (Fe, Zn, Cu, and Ni). Leaf and pod wall iron concentrations increased as much as 500% in transgenic plants, while seed iron concentrations only increased by 10%, suggesting that factors other than leaf and pod wall reductase activity were limiting the translocation of iron to seeds. Protoplasts isolated from transgenic leaves had three-fold higher reductase activity than controls. Expression levels of the iron storage protein, ferritin, were higher in the transgenic leaves than in wild-type, suggesting that the excess iron may be stored as ferritin in the leaves and therefore unavailable for phloem loading and delivery to the seeds. Also, citrate and malate levels in the roots and leaves of transgenic plants were significantly higher than in wild-type, suggesting that organic acid production could be related to the increased accumulation of minerals in roots, leaves, and pod walls, but not in the seeds. All together, these results suggest a more ubiquitous role for the iron reductase in whole-plant mineral accumulation and distribution. PMID:24765096

CASIROZ: Root parameters and types of ectomycorrhiza of young beech plants exposed to different ozone and light regimes.

PubMed

Zeleznik, P; Hrenko, M; Then, C; Koch, N; Grebenc, T; Levanic, T; Kraigher, H

2007-03-01

Tropospheric ozone (O(3)) triggers physiological changes in leaves that affect carbon source strength leading to decreased carbon allocation below-ground, thus affecting roots and root symbionts. The effects of O(3) depend on the maturity-related physiological state of the plant, therefore adult and young forest trees might react differently. To test the applicability of young beech plants for studying the effects of O(3) on forest trees and forest stands, beech seedlings were planted in containers and exposed for two years in the Kranzberg forest FACOS experiment (Free-Air Canopy O(3) Exposure System, http://www.casiroz.de ) to enhanced ozone concentration regime (ambient [control] and double ambient concentration, not exceeding 150 ppb) under different light conditions (sun and shade). After two growing seasons the biomass of the above- and below-ground parts, beech roots (using WinRhizo programme), anatomical and molecular (ITS-RFLP and sequencing) identification of ectomycorrhizal types and nutrient concentrations were assessed. The mycorrhization of beech seedlings was very low ( CA. 5 % in shade, 10 % in sun-grown plants), no trends were observed in mycorrhization (%) due to ozone treatment. The number of Cenococcum geophilum type of ectomycorrhiza, as an indicator of stress in the forest stands, was not significantly different under different ozone treatments. It was predominantly occurring in sun-exposed plants, while its majority share was replaced by Genea hispidula in shade-grown plants. Different light regimes significantly influenced all parameters except shoot/root ratio and number of ectomycorrhizal types. In the ozone fumigated plants the number of types, number of root tips per length of 1 to 2 mm root diameter, root length density per volume of soil and concentration of Mg were significantly lower than in control plants. Trends to a decrease were found in root, shoot, leaf, and total dry weights, total number of root tips, number of vital mycorrhizal root tips, fine root (mass) density, root tip density per surface, root area index, concentration of Zn, and Ca/Al ratio. Due to the general reduction in root growth indices and nutrient cycling in ozone-fumigated plants, alterations in soil carbon pools could be predicted.

Nitrogen fluxes through unsaturated zones in five agricultural settings across the United States

USGS Publications Warehouse

Green, C.T.; Fisher, L.H.; Bekins, B.A.

2008-01-01

The main physical and chemical controls on nitrogen (N) fluxes between the root zone and the water table were determined for agricultural sites in California, Indiana, Maryland, Nebraska, and Washington from 2004 to 2005. Sites included irrigated and nonirrigated fields; soil textures ranging from clay to sand; crops including corn, soybeans, almonds, and pasture; and unsaturated zone thicknesses ranging from 1 to 22 m. Chemical analyses of water from lysimeters and shallow wells indicate that advective transport of nitrate is the dominant process affecting the flux of N below the root zone. Vertical profiles of (i) nitrogen species, (ii) stable isotopes of nitrogen and oxygen, and (iii) oxygen, N, and argon in unsaturated zone air and correlations between N and other agricultural chemicals indicate that reactions do not greatly affect N concentrations between the root zone and the capillary fringe. As a result, physical factors, such as N application rate, water inputs, and evapotranspiration, control the differences in concentrations among the sites. Concentrations of N in shallow lysimeters exhibit seasonal variation, whereas concentrations in lysimeters deeper than a few meters are relatively stable. Based on concentration and recharge estimates, fluxes of N through the deep unsaturated zone range from 7 to 99 kg ha-1 yr-1. Vertical fluxes of N in ground water are lower due to spatial and historical changes in N inputs. High N fluxes are associated with coarse sediments and high N application rates. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Drought, Abscisic Acid and Transpiration Rate Effects on the Regulation of PIP Aquaporin Gene Expression and Abundance in Phaseolus vulgaris Plants

PubMed Central

AROCA, RICARDO; FERRANTE, ANTONIO; VERNIERI, PAOLO; CHRISPEELS, MAARTEN J.

2006-01-01

• Background and Aims Drought causes a decline of root hydraulic conductance, which aside from embolisms, is governed ultimately by aquaporins. Multiple factors probably regulate aquaporin expression, abundance and activity in leaf and root tissues during drought; among these are the leaf transpiration rate, leaf water status, abscisic acid (ABA) and soil water content. Here a study is made of how these factors could influence the response of aquaporin to drought. • Methods Three plasma membrane intrinsic proteins (PIPs) or aquaporins were cloned from Phaseolus vulgaris plants and their expression was analysed after 4 d of water deprivation and also 1 d after re-watering. The effects of ABA and of methotrexate (MTX), an inhibitor of stomatal opening, on gene expression and protein abundance were also analysed. Protein abundance was examined using antibodies against PIP1 and PIP2 aquaporins. At the same time, root hydraulic conductance (L), transpiration rate, leaf water status and ABA tissue concentration were measured. • Key Results None of the treatments (drought, ABA or MTX) changed the leaf water status or tissue ABA concentration. The three treatments caused a decline in the transpiration rate and raised PVPIP2;1 gene expression and PIP1 protein abundance in the leaves. In the roots, only the drought treatment raised the expression of the three PIP genes examined, while at the same time diminishing PIP2 protein abundance and L. On the other hand, ABA raised both root PIP1 protein abundance and L. • Conclusions The rise of PvPIP2;1 gene expression and PIP1 protein abundance in the leaves of P. vulgaris plants subjected to drought was correlated with a decline in the transpiration rate. At the same time, the increase in the expression of the three PIP genes examined caused by drought and the decline of PIP2 protein abundance in the root tissues were not correlated with any of the parameters measured. PMID:17028296

Rhizobial Nodulation Factors Stimulate Mycorrhizal Colonization of Nodulating and Nonnodulating Soybeans.

PubMed

Xie, Z. P.; Staehelin, C.; Vierheilig, H.; Wiemken, A.; Jabbouri, S.; Broughton, W. J.; Vogeli-Lange, R.; Boller, T.

1995-08-01

Legumes form tripartite symbiotic associations with noduleinducing rhizobia and vesicular-arbuscular mycorrhizal fungi. Co-inoculation of soybean (Glycine max [L.] Merr.) roots with Bradyrhizobium japonicum 61-A-101 considerably enhanced colonization by the mycorrhizal fungus Glomus mosseae. A similar stimulatory effect on mycorrhizal colonization was also observed in nonnodulating soybean mutants when inoculated with Bradyrhizobium japonicum and in wild-type soybean plants when inoculated with ineffective rhizobial strains, indicating that a functional rhizobial symbiosis is not necessary for enhanced mycorrhiza formation. Inoculation with the mutant Rhizobium sp. NGR[delta]nodABC, unable to produce nodulation (Nod) factors, did not show any effect on mycorrhiza. Highly purified Nod factors also increased the degree of mycorrhizal colonization. Nod factors from Rhizobium sp. NGR234 differed in their potential to promote fungal colonization. The acetylated factor NodNGR-V (MeFuc, Ac), added at concentrations as low as 10-9 M, was active, whereas the sulfated factor, NodNGR-V (MeFuc, S), was inactive. Several soybean flavonoids known to accumulate in response to the acetylated Nod factor showed a similar promoting effect on mycorrhiza. These results suggest that plant flavonoids mediate the Nod factor-induced stimulation of mycorrhizal colonization in soybean roots.

Rhizobial Nodulation Factors Stimulate Mycorrhizal Colonization of Nodulating and Nonnodulating Soybeans.

PubMed Central

Xie, Z. P.; Staehelin, C.; Vierheilig, H.; Wiemken, A.; Jabbouri, S.; Broughton, W. J.; Vogeli-Lange, R.; Boller, T.

1995-01-01

Legumes form tripartite symbiotic associations with noduleinducing rhizobia and vesicular-arbuscular mycorrhizal fungi. Co-inoculation of soybean (Glycine max [L.] Merr.) roots with Bradyrhizobium japonicum 61-A-101 considerably enhanced colonization by the mycorrhizal fungus Glomus mosseae. A similar stimulatory effect on mycorrhizal colonization was also observed in nonnodulating soybean mutants when inoculated with Bradyrhizobium japonicum and in wild-type soybean plants when inoculated with ineffective rhizobial strains, indicating that a functional rhizobial symbiosis is not necessary for enhanced mycorrhiza formation. Inoculation with the mutant Rhizobium sp. NGR[delta]nodABC, unable to produce nodulation (Nod) factors, did not show any effect on mycorrhiza. Highly purified Nod factors also increased the degree of mycorrhizal colonization. Nod factors from Rhizobium sp. NGR234 differed in their potential to promote fungal colonization. The acetylated factor NodNGR-V (MeFuc, Ac), added at concentrations as low as 10-9 M, was active, whereas the sulfated factor, NodNGR-V (MeFuc, S), was inactive. Several soybean flavonoids known to accumulate in response to the acetylated Nod factor showed a similar promoting effect on mycorrhiza. These results suggest that plant flavonoids mediate the Nod factor-induced stimulation of mycorrhizal colonization in soybean roots. PMID:12228558

GbTCP, a cotton TCP transcription factor, confers fibre elongation and root hair development by a complex regulating system.

PubMed

Hao, Juan; Tu, Lili; Hu, Haiyan; Tan, Jiafu; Deng, Fenglin; Tang, Wenxin; Nie, Yichun; Zhang, Xianlong

2012-10-01

As the most important natural raw material for textile industry, cotton fibres are an excellent model for studying single-cell development. Although expression profiling and functional genomics have provided some data, the mechanism of fibre development is still not well known. A class I TCP transcription factor (designated GbTCP), encoding 344 amino acids, was isolated from the normalized cDNA library of sea-island cotton fibre (from -2 to 25 days post anthesis). GbTCP was preferentially expressed in the elongating cotton fibre from 5 to 15 days post anthesis. Some expression was also observed in stems, apical buds, and petals. RNAi silencing of GbTCP produced shorter fibre, a reduced lint percentage, and a lower fibre quality than the wild-type plants. Overexpression of GbTCP enhanced root hair initiation and elongation in Arabidopsis and regulated branching. Solexa sequencing and Affymetrix GeneChip analysis indicated that GbTCP positively regulates the level of jasmonic acid (JA) and, as a result, activates downstream genes (reactive oxygen species, calcium signalling, ethylene biosynthesis and response, and several NAC and WRKY transcription factors) necessary for elongation of fibres and root hairs. JA content analysis in cotton also confirmed that GbTCP has a profound effect on JA biosynthesis. In vitro ovule culture showed that an appropriate concentration of JA promoted fibre elongation. The results suggest that GbTCP is an important transcription factor for fibre and root hair development by regulating JA biosynthesis and response and other pathways, including reactive oxygen species, calcium channel and ethylene signalling.

GbTCP, a cotton TCP transcription factor, confers fibre elongation and root hair development by a complex regulating system

PubMed Central

Zhang, Xianlong

2012-01-01

As the most important natural raw material for textile industry, cotton fibres are an excellent model for studying single-cell development. Although expression profiling and functional genomics have provided some data, the mechanism of fibre development is still not well known. A class I TCP transcription factor (designated GbTCP), encoding 344 amino acids, was isolated from the normalized cDNA library of sea-island cotton fibre (from –2 to 25 days post anthesis). GbTCP was preferentially expressed in the elongating cotton fibre from 5 to 15 days post anthesis. Some expression was also observed in stems, apical buds, and petals. RNAi silencing of GbTCP produced shorter fibre, a reduced lint percentage, and a lower fibre quality than the wild-type plants. Overexpression of GbTCP enhanced root hair initiation and elongation in Arabidopsis and regulated branching. Solexa sequencing and Affymetrix GeneChip analysis indicated that GbTCP positively regulates the level of jasmonic acid (JA) and, as a result, activates downstream genes (reactive oxygen species, calcium signalling, ethylene biosynthesis and response, and several NAC and WRKY transcription factors) necessary for elongation of fibres and root hairs. JA content analysis in cotton also confirmed that GbTCP has a profound effect on JA biosynthesis. In vitro ovule culture showed that an appropriate concentration of JA promoted fibre elongation. The results suggest that GbTCP is an important transcription factor for fibre and root hair development by regulating JA biosynthesis and response and other pathways, including reactive oxygen species, calcium channel and ethylene signalling. PMID:23105133

Sweets for the foe - effects of nonstructural carbohydrates on the susceptibility of Quercus robur against Phytophthora quercina.

PubMed

Angay, Oguzhan; Fleischmann, Frank; Recht, Sabine; Herrmann, Sylvie; Matyssek, Rainer; Oßwald, Wolfgang; Buscot, François; Grams, Thorsten E E

2014-09-01

The root-rot pathogen Phytophthora quercina is a key determinant of oak decline in Europe. The susceptibility of pedunculate oak (Quercus robur) to this pathogen has been hypothesized to depend on the carbon availability in roots as an essential resource for defense. Microcuttings of Q. robur undergo an alternating rhythm of root and shoot growth. Inoculation of mycorrhizal (Piloderma croceum) and nonmycorrhizal oak roots with P. quercina was performed during both growth phases, that is, root flush (RF) and shoot flush (SF). Photosynthetic and morphological responses as well as concentrations of nonstructural carbohydrates (NSC) were analyzed. Infection success was quantified by the presence of pathogen DNA in roots. Concentrations of NSC in roots depended on the alternating root/shoot growth rhythm, being high and low during RF and SF, respectively. Infection success was high during RF and low during SF, resulting in a significantly positive correlation between pathogen DNA and NSC concentration in roots, contrary to the hypothesis. The alternating growth of roots and shoots plays a crucial role for the susceptibility of lateral roots to the pathogen. NSC availability in oak roots has to be considered as a benchmark for susceptibility rather than resistance against P. quercina. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Phytoextraction: simulating uptake and translocation of arsenic in a soil-plant system.

PubMed

Ouyang, Ying

2005-01-01

The uptake, transport, and accumulation of metals by plants are functions central to successful phytoextraction. This study investigates the uptake and translocation of arsenic from a contaminated sandy soil by a mature Chinese brake fern (Pteris vittata L.). An existing mathematical model for the coupled transport of water, heat, and solutes in the soil-plant-atmosphere continuum (CTSPAC) was modified to examine the flow of water as well as the uptake and translocation of total arsenic in the xylem of the fern. This model was calibrated using greenhouse measurements before its application. Simulation results showed that about 20% of the soil arsenic was removed by the fern in 10 d, of which about 90% of the arsenic was stored in the fronds and 10% in the roots. Although arsenic mass in the plant tissues increased consecutively with time, arsenic concentration in the xylem sap of the root tips has a typical diurnal distribution pattern: increasing during the day and decreasing at night, resulting from daily variations of frond surface water transpiration. The largest difference in simulated arsenic concentration in the root tips between the day and night was about 5%. This study also suggests that the use of transpiration stream concentration factor (TSCF), which is defined as the ratio of chemical concentration in the xylem sap to that in the external solution, to evaluate the translocation efficiency of arsenic for the hyperaccumulator Chinese brake fern (Pteris vittata L.) could be limited.

The Autoregulation Gene SUNN Mediates Changes in Root Organ Formation in Response to Nitrogen through Alteration of Shoot-to-Root Auxin Transport1[W][OA

PubMed Central

Jin, Jian; Watt, Michelle; Mathesius, Ulrike

2012-01-01

We tested whether a gene regulating nodule number in Medicago truncatula, Super Numeric Nodules (SUNN ), is involved in root architecture responses to carbon (C) and nitrogen (N) and whether this is mediated by changes in shoot-to-root auxin transport. Nodules and lateral roots are root organs that are under the control of nutrient supply, but how their architecture is regulated in response to nutrients is unclear. We treated wild-type and sunn-1 seedlings with four combinations of low or increased N (as nitrate) and C (as CO2) and determined responses in C/N partitioning, plant growth, root and nodule density, and changes in auxin transport. In both genotypes, nodule density was negatively correlated with tissue N concentration, while only the wild type showed significant correlations between N concentration and lateral root density. Shoot-to-root auxin transport was negatively correlated with shoot N concentration in the wild type but not in the sunn-1 mutant. In addition, the ability of rhizobia to alter auxin transport depended on N and C treatment as well as the SUNN gene. Nodule and lateral root densities were negatively correlated with auxin transport in the wild type but not in the sunn-1 mutant. Our results suggest that SUNN is required for the modulation of shoot-to-root auxin transport in response to altered N tissue concentrations in the absence of rhizobia and that this controls lateral root density in response to N. The control of nodule density in response to N is more likely to occur locally in the root. PMID:22399647

Uptake, translocation and transformation of antimony in rice (Oryza sativa L.) seedlings.

PubMed

Cai, Fei; Ren, Jinghua; Tao, Shu; Wang, Xilong

2016-02-01

Antimony (Sb), as a toxic metalloid, has been gaining increasing research concerns due mainly to its severe pollution in many places. Rice has been identified to be the dominant intake route of Sb by residents close to the Sb mining areas. A hydroponic experiment was conducted to investigate the difference in uptake, translocation and transformation of Sb in rice seedlings of four cultivars exposed to 0.2 or 1.0 mg/L of Sb(V). The results showed that mass concentration of iron plaque (mg/kg FW) formed at the root surfaces of cultivar N was the highest among all tested cultivars at both low and high exposure levels of Sb(V). The accumulated Sb concentration in iron plaque significantly increased with an increase in mass concentration of iron plaque formed at the rice root. The total amount of iron plaque (mg/pot) at rice root generally increased with increasing exposed Sb(V) concentration, which was closely associated with the increasing lipid peroxidation in roots. Concentration percentage of Sb in rice root significantly reduced as the corresponding value in the iron plaque increased, suggesting that iron plaque formation strongly suppressed uptake of Sb by rice root. Sb concentration in rice tissues followed an order: root > stem, leaf. The japonica rice (cultivars N and Z) exhibited a stronger translocation tendency of Sb from root to stem than indica hybrid rice (cultivars F and G). Translocation of Sb from root of cultivar F to its stem and leaf was sharply enhanced with increasing Sb exposure concentration. Sb(V) could be reduced to Sb(III) in rice tissues, especially in stems (10-26% of the total Sb). For the sake of food safety, the difference in uptake, translocation and transformation of Sb in rice species planted in Sb-contaminated soils should be taken into consideration. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hairy root culture optimization and resveratrol production from Vitis vinifera subsp. sylvesteris.

PubMed

Hosseini, Sayed Mehdi; Bahramnejad, Bahman; Douleti Baneh, Hamed; Emamifar, Aryo; Goodwin, Paul H

2017-04-01

Resveratrol is a polyphenolic compound produced in very low levels in grapes. To achieve high yield of resveratrol in wild grape, three Agrobacterium rhizogenes strains, Ar318, ArA4 and LBA9402, were used to induce hairy roots following infection of internodes, nodes or petioles of in vitro grown Vitis vinifera subsp. sylvesteris accessions W2 and W16, and cultivar Rasha. The effects of inoculation time, age of explants, bacterial concentration and co-cultivation times were examined on the efficiency of the production of hairy roots. Strains Ar318, ArA4 and LBA9402 all induced hairy roots in the tested genotypes, but the efficiency of ArA4 strain was higher than the other strains. The highest hairy root production was with using internodes as explants. The transformation of hairy roots lines was confirmed by PCR detection of rolB gene. Half Murashige and Skoog (MS) medium was better for biomass production compared with MS medium. HPLC analysis of resveratrol production in the hairy root cultures showed that all the genotypes produced higher amounts of resveratrol than control roots. The highest amount of resveratrol was produced from W16 internode cultures, which was 31-fold higher than that of control root. Furthermore, TLC analysis showed that treatments of hairy roots with sodium acetate and jasmonate elevated resveratrol levels both in hairy root tissue and excreted into the half MS medium. These results demonstrate that endogenous and exogenous factors can affect resveratrol production in hairy root culture of grape, and this strategy could be used to increase low resveratrol production in grapes.

[Effects of elevated ozone concentrations on enzyme activities and organic acids content in wheat rhizospheric soil.

PubMed

Yin, Wei Qin; Jing, Hao Qi; Wang, Ya Bo; Wei, Si Yu; Sun, Yue; Wang, Sheng Sen; Wang, Xuai Zhi

2018-02-01

The elevated concentration of tropospheric ozone (O 3 ) is an important global climate change driver, with adverse impacts on soil ecological environment and crop growth. In this study, a pot experiment was carried out in an open top chamber (OTC), to investigate the effects of elevated ozone concentration on soil enzyme activities (catalase, polyphenol oxidase, dehydrogenase and invertase), organic acids contents (oxalic acid, citric acid and malic acid) at different growth stages (tillering, jointing, heading and ripening stages) of wheat, and combined with the rhizospheric soil physicochemical properties and plant root characteristics to analyze the underlying reasons. The results showed that, elevated ozone concentration increased soil catalase, polyphenol oxidase, dehydrogenase and invertase activities at wheat ripening period to different degrees, with the effects on the activities of catalase and polyphenol oxidase being statistically significant. At the heading stage, activities of dehydrogenase and invertase were significantly increased by up to 76.7%. At the ripening stage, elevated ozone concentration significantly increased the content of citric acid and malic acid and redox potential (Eh) in rhizospheric soil, but reduced soil pH, electrical conductivity, total carbon and nitrogen. For root characteristics, elevated ozone concentrations significantly reduced the wheat root biomass, total root length and root surface area but increased the average root diameter.

Organic acids, amino acids compositions in the root exudates and Cu-accumulation in castor (Ricinus communis L.) Under Cu stress.

PubMed

Huang, Guoyong; Guo, Guangguang; Yao, Shiyuan; Zhang, Na; Hu, Hongqing

2016-01-01

Ricinus communis L. is a hyperaccumulation plant newly discovered in an abandoned land of Cu mine in China. A hydroponic experiment was then carried out to determine the root exudates in the Cu-tolerant castor (Ricinus communis L.). Plants were grown in nutrient solution with increasing level of Cu doses (0, 100, 250, 500, and 750 μmol/L Cu) in the form of CuSO4. Cu accumulation in the roots and shoots of castor, and root exudates collected from the castor were measured. The results indicated that the castor had a high Cu accumulation capacity and the Cu concentrations in the shoots and roots of the castor treated with 750 μmol/L Cu were 177.1, 14586.7 mg/kg, respectively. Tartaric was the largest in the root exudates in terms of concentrations, which reached up to 329.13 μmol/g (dry plant) in the level of 750 μmol/L Cu. There was a significantly positive linear relationship between the Cu concentration in root and the concentration of succinic (R = 0.92, P < 0.05), tartaric (R = 0.96, P < 0.01), and citric (R = 0.89, P < 0.05). These results indicated that the difference in root exudation from castor could affect their Cu tolerance. What is more, significant is that the high tartaric and citric, the low oxalic and cysteine in the root exudation of castor contributed to toleration of high Cu concentrations.

Different Phylogenetic and Environmental Controls of First-order Root Morphological and Chemical Traits

NASA Astrophysics Data System (ADS)

Wang, R.; Wang, Q.; Zhao, N.; Yu, G.; He, N.

2017-12-01

Fine roots are the most distal roots that act as the primary belowground organs in acquiring limiting nutrients and water from the soil. However, limited by the inconsistency in definitions of fine roots and the different protocols among studies, knowledge of root system traits has, to date, still lagged far behind our understanding of above-ground traits. In particular, whether variation in fine root traits among the plant species along a single root economics spectrum and this underlying mechanism are still hotly debated. In this study, we sampled the first-order root using the standardized protocols, and measured six important root traits related to resource use strategies, from 181 plant species from subtropical to boreal forests. Base on this large dataset, we concluded that different phylogenetic and environmental factors affected on root thickness and nutrient, resulting in the decoupled pattern between them. Specifically, variation in species-level traits related to root thickness (including root diameter, RD and specific root length, SRL) was restricted by common ancestry and little plastic to the changing environments, whereas the large-scale variation in woody root nutrient was mainly controlled by environmental differences, especially soil variables. For community-level traits, mean annual temperature (MAT) mainly influenced the community-level root thickness through the direct effect of changes in plant species composition, while soil P had a positive influence effect on community-level root nitrogen concentration (CWM_RN), reflecting the strong influence of soil fertility on belowground root nutrient. The different environmental constraints and selective pressures acting between root thickness and nutrient traits allows for multiple ecological strategies to adapt to complex environmental conditions. In addition, strong relationships between community-level root traits and environmental variables, due to environmental filters, indicate that in contrast with individual species-level trait, community-aggregated root traits could be used to improve our ability to predict how the distribution of vegetation will change in response to a changing climate.

Phytoremediation potential of transplanted bare-root seedlings of trees for lead/zinc and copper mine tailings.

PubMed

Shi, Xiang; Chen, Yi-Tai; Wang, Shu-Feng; Pan, Hong-Wei; Sun, Hai-Jing; Liu, Cai-Xia; Liu, Jian-Feng; Jiang, Ze-Ping

2016-11-01

Selecting plant species that can overcome unfavorable conditions and increase the recovery of degraded mined lands remains a challenge. A pot experiment was conducted to evaluate the feasibility of using transplanted tree seedlings for the phytoremediation of lead/zinc and copper mine tailings. One-year-old bare-root of woody species (Rhus chinensis Mill, Quercus acutissima Carruth, Liquidambar formosana Hance, Vitex trifolia Linn. var. simplicifolia Cham, Lespedeza cuneata and Amorpha fruticosa Linn) were transplanted into pots with mine tailings and tested as potential metal-tolerant plants. Seedling survival, plant growth, root trait, nutrient uptake, and metal accumulation and translocation were assessed. The six species grew in both tailings and showed different tolerance level. A. fruticosa was highly tolerant of Zn, Pb and Cu, and grew normally in both tailings. Metal concentrations were higher in the roots than in the shoots of the six species. All of the species had low bioconcentration and translocation factor values. However, R. chinensis and L. formosana had significantly higher translocation factor values for Pb (0.88) and Zn (1.78) than the other species. The nitrogen-fixing species, A. fruticosa, had the highest tolerance and biomass production, implying that it has great potential in the phytoremediation of tailing areas in southern China.

Root exudate as major player on soil-water retention dynamics

NASA Astrophysics Data System (ADS)

Albalasmeh, A. A.; Sweet, J. R.; Gebrenegus, T. B.; Ghezzehei, T. A.

2012-12-01

Plant roots and soil microbes release 5-60% of the entirety of photosynthetically fixed carbon in to the soil as exudates to adapt to their surrounding. There is indirect evidence suggesting that these exudates play a major role in altering the of the soil water retention properties. In this study, we used a uniformly sized (40 μm) glass beads and various concentrations (0, 2, 10, 20 and 29 g/L) of polygalacutronic acid (PGA) to mimic sandy soil and the organic exudates from plant roots, respectively. The samples were subjected to periods of drying and subsequent equilibration. At each stage, the water potential was measured using WP4C Dewpoint PotentiaMeter. The effect of root exudates on soil water retention can be attributed t at least two factors. The most widely speculated effect is through enhanced of soil aggregation. This effect is primarily due to capillary adhesion in fine pores within aggregates and is consistent was visual observation of pronounced aggregation in many rhizosphere soils. The second factor is related to osmotic effect of the exudate solution. Our observations show that the capillary effect is mostly to higher water potential regime (> -1 bar suction). Whereas the osmotic effect dominates in <- 1 bar suction. These results will provide direct quantitative evidence of how rhizosphere organic matter helps plant-soil relations.

Mathematical modelling of the uptake and transport of salt in plant roots.

PubMed

Foster, Kylie J; Miklavcic, Stanley J

2013-11-07

In this paper, we present and discuss a mathematical model of ion uptake and transport in roots of plants. The underlying physical model of transport is based on the mechanisms of forced diffusion and convection. The model can take account of local variations in effective ion and water permeabilities across the major tissue regions of plant roots, represented through a discretized coupled system of governing equations including mass balance, forced diffusion, convection and electric potential. We present simulation results of an exploration of the consequent enormous parameter space. Among our findings we identify the electric potential as a major factor affecting ion transport across, and accumulation in, root tissues. We also find that under conditions of a constant but realistic level of bulk soil salt concentration and plant-soil hydraulic pressure, diffusion plays a significant role even when convection by the water transpiration stream is operating. Crown Copyright © 2013 Published by Elsevier Ltd. All rights reserved.

Assessment of allelopathic properties of Aloe ferox Mill. on turnip, beetroot and carrot.

PubMed

Arowosegbe, Sunday; Afolayan, Anthony J

2012-01-01

Turnip (Brassica rapa var. rapa L.), beetroot (Beta vulgaris L.) and carrot (Daucus carota L.) are common vegetables in South Africa. The allelopathic potential of aqueous leaf and root extracts of Aloe ferox Mill.- a highly valued medicinal plant- was evaluated against seed germination and seedling growth of the three vegetables in Petri dish experiments. The extracts were tested at concentrations of 2, 4, 6, 8, and 10 mg/mL. Leaf extract concentrations above 4 mg/mL inhibited the germination of all the crops, while the root extract had no significant effect on germination irrespective of concentration. Interestingly, the lowest concentration of leaf extract stimulated root length elongation of beetroot by 31.71%. Other concentrations significantly inhibited both root and shoot growth of the vegetable crops except the turnip shoot. The most sensitive crop was carrot, with percentage inhibition ranging from 29.15 to 100% for root and shoot lengths. Lower percentage inhibition was observed for the root extract than the leaf extract against shoot growth of beetroot and carrot. The results from this study suggested the presence of allelochemicals mostly in the leaves of A. ferox that could inhibit the growth of the turnip, beetroot and carrot.

Beyond toxicity: a regulatory role for mitochondrial cyanide.

PubMed

García, Irene; Gotor, Cecilia; Romero, Luis C

2014-01-01

In non-cyanogenic plants, cyanide is a co-product of ethylene and camalexin biosynthesis. To maintain cyanide at non-toxic levels, Arabidopsis plants express the mitochondrial β-cyanoalanine synthase CYS-C1. CYS-C1 knockout leads to an increased level of cyanide in the roots and leaves and a severe defect in root hair morphogenesis, suggesting that cyanide acts as a signaling factor in root development. During compatible and incompatible plant-bacteria interactions, cyanide accumulation and CYS-C1 gene expression are negatively correlated. Moreover, CYS-C1 mutation increases both plant tolerance to biotrophic pathogens and their susceptibility to necrotrophic fungi, indicating that cyanide could stimulate the salicylic acid-dependent signaling pathway of the plant immune system. We hypothesize that CYS-C1 is essential for maintaining non-toxic concentrations of cyanide in the mitochondria to facilitate cyanide's role in signaling.

Effect of elevated CO₂ on phosphorus nutrition of phosphate-deficient Arabidopsis thaliana (L.) Heynh under different nitrogen forms.

PubMed

Niu, Yaofang; Chai, Rushan; Dong, Huifen; Wang, Huan; Tang, Caixian; Zhang, Yongsong

2013-01-01

Phosphorus (P) nutrition is always a key issue regarding plants responses to elevated CO(2). Yet it is unclear of how elevated CO(2) affects P uptake under different nitrogen (N) forms. This study investigated the influence of elevated CO(2) (800 µl l(-1)) on P uptake and utilization by Arabidopsis grown in pH-buffered phosphate (P)-deficient (0.5 µM) hydroponic culture supplying with 2mM nitrate (NO(3)(-)) or ammonium (NH(4)(+)). After 7 d treatment, elevated CO(2) enhanced the biomass production of both NO(3)(-)- and NH(4) (+)-fed plants but decreased the P amount absorbed per weight of roots and the P concentration in the shoots of plants supplied with NH(4)(+). In comparison, elevated CO(2) increased the amount of P absorbed per weight of roots, as well as the P concentration in plants and alleviated P deficiency-induced symptoms of plants supplied with NO(3)(-). Elevated CO(2) also increased the root/shoot ratio, total root surface area, and acid phosphatase activity, and enhanced the expression of genes or transcriptional factors involving in P uptake, allocation and remobilization in P deficient plants. Furthermore, elevated CO(2) increased the nitric oxide (NO) level in roots of NO(3)(-)-fed plants but decreased it in NH(4)(+)-fed plants. NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) inhibited plant P acquisition by roots under elevated CO(2). Considering all of these findings, this study concluded that a combination of elevated CO(2) and NO(3)(-) nutrition can induce a set of plant adaptive strategies to improve P status from P-deficient soluble sources and that NO may be a signalling molecule that controls these processes.

Root-derived auxin contributes to the phosphorus-deficiency-induced cluster-root formation in white lupin (Lupinus albus).

PubMed

Meng, Zhi Bin; You, Xue Di; Suo, Dong; Chen, Yun Long; Tang, Caixian; Yang, Jian Li; Zheng, Shao Jian

2013-08-01

Formation of cluster roots is a typical morphological response to phosphorus (P) deficiency in white lupin (Lupinus albus), but its physiological and molecular mechanisms are still unclear. We investigated the role of auxin in the initiation of cluster roots by distinguishing the sources of auxin, measuring the longitudinal distribution patterns of free indole-3-acetic acid (IAA) along the root and the related gene expressions responsible for polar auxin transport (PAT) in different developmental stages of cluster roots. We found that removal of shoot apex or primary root apex and application of auxin-influx or -efflux transport inhibitors, 3-chloro-4-hydroxyphenylacetic acid, N-1-naphthylphthalamic acid and 2,3,5-triiodobenzoic acid, to the stem did not affect the number of cluster roots and the free-IAA concentration in the roots of P-deficient plants, but when these inhibitors were applied directly to the growth media, the cluster-root formation was greatly suppressed, suggesting the fundamental role of root-derived IAA in cluster-root formation. The concentration of free IAA in the roots was higher in P-deficient plants than in P-adequate ones, and the highest in the lateral-root apex and the lowest in the mature cluster roots. Meanwhile the expression patterns of LaAUX1, LaPIN1 and LaPIN3 transcripts related to PAT was consistent with concentrations of free IAA along the lateral root, indicating the contribution of IAA redistribution in the cluster-root development. We proposed that root-derived IAA plays a direct and important role in the P-deficiency-induced formation of cluster roots. Copyright © Physiologia Plantarum 2012.

Chromate and phosphate inhibited each other's uptake and translocation in arsenic hyperaccumulator Pteris vittata L.

PubMed

de Oliveira, Letúzia M; Lessl, Jason T; Gress, Julia; Tisarum, Rujira; Guilherme, Luiz R G; Ma, Lena Q

2015-02-01

We investigated the effects of chromate (CrVI) and phosphate (P) on their uptake and translocation in As-hyperaccumulator Pteris vittata (PV). Plants were exposed to 1) 0.10 mM CrVI and 0, 0.25, 1.25, or 2.50 mM P or 2) 0.25 mM P and 0, 0.50, 2.5 or 5.0 mM CrVI for 24 h in hydroponics. PV accumulated 2919 mg/kg Cr in the roots at CrVI₀.₁₀, and 5100 and 3500 mg/kg P in the fronds and roots at P₀.₂₅. When co-present, CrVI and P inhibited each other's uptake in PV. Increasing P concentrations reduced Cr root concentrations by 62-82% whereas increasing CrVI concentrations reduced frond P concentrations by 52-59% but increased root P concentrations by 11-15%. Chromate reduced P transport, with more P being accumulated in PV roots. Though CrVI was supplied, 64-78% and 92-93% CrIII were in PV fronds and roots. Based on X-ray diffraction, Cr₂O₃ was detected in the roots confirming CrVI reduction to CrIII by PV. In short, CrVI and P inhibited each other in uptake and translocation by PV, and CrVI reduction to CrIII in PV roots served as its detoxification mechanism. The finding helps to understand the interactions of P and Cr during their uptake in PV. Published by Elsevier Ltd.

ABA Suppresses Root Hair Growth via the OBP4 Transcriptional Regulator1[OPEN

PubMed Central

Kawamura, Ayako; Schäfer, Sabine; Breuer, Christian; Shibata, Michitaro; Mitsuda, Nobutaka; Ohme-Takagi, Masaru; Matsui, Minami

2017-01-01

Plants modify organ growth and tune morphogenesis in response to various endogenous and environmental cues. At the cellular level, organ growth is often adjusted by alterations in cell growth, but the molecular mechanisms underlying this control remain poorly understood. In this study, we identify the DNA BINDING WITH ONE FINGER (DOF)-type transcription regulator OBF BINDING PROTEIN4 (OBP4) as a repressor of cell growth. Ectopic expression of OBP4 in Arabidopsis (Arabidopsis thaliana) inhibits cell growth, resulting in severe dwarfism and the repression of genes involved in the regulation of water transport, root hair development, and stress responses. Among the basic helix-loop-helix transcription factors known to control root hair growth, OBP4 binds the ROOT HAIR DEFECTIVE6-LIKE2 (RSL2) promoter to repress its expression. The accumulation of OBP4 proteins is detected in expanding root epidermal cells, and its expression level is increased by the application of abscisic acid (ABA) at concentrations sufficient to inhibit root hair growth. ABA-dependent induction of OBP4 is associated with the reduced expression of RSL2. Furthermore, ectopic expression of OBP4 or loss of RSL2 function results in ABA-insensitive root hair growth. Taken together, our results suggest that OBP4-mediated transcriptional repression of RSL2 contributes to the ABA-dependent inhibition of root hair growth in Arabidopsis. PMID:28167701

Soil-to-plant transfer factors of natural radionuclides (226Ra and 40K) in selected Thai medicinal plants.

PubMed

Saenboonruang, Kiadtisak; Phonchanthuek, Endu; Prasandee, Kamonkhuan

2018-04-01

A soil-to-plant transfer factor (TF) is an important parameter that could be used to estimate radionuclides levels in medicinal plants. This work reports concentrations of natural radionuclides ( 226 Ra and 40 K) and TFs in six Thai medicinal plants grown in central Thailand using an HPGe gamma ray spectrometer. Either root, leaf, or flower parts of each medicinal plant were selected for use in the investigation according to their practical uses in traditional medicine. The results showed that due to K being essential in plants, 40 K had higher arithmetic means of activity concentrations and geometric means of TFs (geometric standard deviations in parentheses) of 610 ± 260 Bq kg -1 dry weight (DW) and 2.0 (1.4), respectively, than 226 Ra, which had the activity concentrations and TFs of 4.8 ± 2.6 Bq kg -1 DW and 0.17 (1.8), respectively. The results also showed that the leaves of medicinal plants had higher activity concentrations and TFs than root and flower parts, probably due to higher metabolic activities in leaves. Furthermore, there was good agreement between the results from the current work and other similar reports on medicinal plants. The information obtained from this work could strengthen knowledge of natural radionuclides in plants and particularly increase available TF data on Thai medicinal plants. Copyright © 2018 Elsevier Ltd. All rights reserved.

The paradoxical distribution of a shallow-rooted keystone species away from surface water, near the water-limited edge of its range in the Sonoran Desert: Seed-seedling conflicts

NASA Astrophysics Data System (ADS)

Drezner, Taly Dawn

2013-02-01

Species distributions reflect limiting factors, particularly near the margins of their range where density and abundance decrease as environmental factors decrease or increase to non-optimal conditions. I test whether the keystone saguaro cactus (Carnegiea gigantea), a shallow-rooted species, is indeed distributed disproportionately in areas of concentrated drainage (runnels) in a water-limited population. Carnegiea and a common nurse were sampled at a marginal site in and out of areas with concentrated surface water and chi-square analysis was used to determine the pattern of distribution. In this study I found that, surprisingly, near the hot, water-limited edge of their range, C. gigantea are found significantly less often in areas where more water would be available to them. For example, while only 20% of nurses were on interfluves, half of Carnegiea protégé were there. One possible explanation is that the subsequent redistribution of seeds by water away from preferred microsites may be important in shaping the final pattern of successful establishment. The shallow-rooted Carnegiea relies entirely on surface water for its moisture; it is thus paradoxical that the surface water so fundamentally essential to its survival throughout its life appears to hinder its establishment in precisely those sites where the greatest surface water would be available, particularly near the water-limited edge of its range.

Responses of nutrient capture and fine root morphology of subalpine coniferous tree Picea asperata to nutrient heterogeneity and competition

PubMed Central

Nan, Hongwei; Liang, Jin; Cheng, Xinying; Zhao, ChunZhang; Yin, HuaJun; Yin, ChunYing; Liu, Qing

2017-01-01

Investigating the responses of trees to the heterogeneous distribution of nutrients in soil and simultaneous presence of neighboring roots could strengthen the understanding of an influential mechanism on tree growth and provide a scientific basis for forest management. Here, we conducted two split-pot experiments to investigate the effects of nutrient heterogeneity and intraspecific competition on the fine root morphology and nutrient capture of Picea asperata. The results showed that P. asperata efficiently captured nutrients by increasing the specific root length (SRL) and specific root area (SRA) of first-and second-order roots and decreasing the tissue density of first-order roots to avoid competition for resources and space with neighboring roots. The nutrient heterogeneity and addition of fertilization did not affect the fine root morphology, but enhanced the P and K concentrations in the fine roots in the absence of a competitor. On the interaction between nutrient heterogeneity and competition, competition decreased the SRL and SRA but enhanced the capture of K under heterogeneous soil compared with under homogeneous soil. Additionally, the P concentration, but not the K concentration, was linearly correlated to root morphology in heterogeneous soil, even when competition was present. The results suggested that root morphological features were only stimulated when the soil nutrients were insufficient for plant growth and the nutrients accumulations by root were mainly affected by the soil nutrients more than the root morphology. PMID:29095947

Phosphate-Dependent Root System Architecture Responses to Salt Stress1[OPEN

PubMed Central

Sommerfeld, Hector Montero; ter Horst, Anneliek; Haring, Michel A.

2016-01-01

Nutrient availability and salinity of the soil affect the growth and development of plant roots. Here, we describe how inorganic phosphate (Pi) availability affects the root system architecture (RSA) of Arabidopsis (Arabidopsis thaliana) and how Pi levels modulate responses of the root to salt stress. Pi starvation reduced main root length and increased the number of lateral roots of Arabidopsis Columbia-0 seedlings. In combination with salt, low Pi dampened the inhibiting effect of mild salt stress (75 mm) on all measured RSA components. At higher salt concentrations, the Pi deprivation response prevailed over the salt stress only for lateral root elongation. The Pi deprivation response of lateral roots appeared to be oppositely affected by abscisic acid signaling compared with the salt stress response. Natural variation in the response to the combination treatment of salt and Pi starvation within 330 Arabidopsis accessions could be grouped into four response patterns. When exposed to double stress, in general, lateral roots prioritized responses to salt, while the effect on main root traits was additive. Interestingly, these patterns were not identical for all accessions studied, and multiple strategies to integrate the signals from Pi deprivation and salinity were identified. By genome-wide association mapping, 12 genomic loci were identified as putative factors integrating responses to salt stress and Pi starvation. From our experiments, we conclude that Pi starvation interferes with salt responses mainly at the level of lateral roots and that large natural variation exists in the available genetic repertoire of accessions to handle the combination of stresses. PMID:27208277

Root characteristics of cover crops and their erosion-reducing potential during concentrated runoff

NASA Astrophysics Data System (ADS)

de Baets, S.; Poesen, J.

2009-04-01

In the loam region in central Belgium, a lot of research has been conducted on the effects of cover crops for preventing splash and interrill erosion and on their nutrient pumping effectiveness. As this is a very effective erosion and environment conservation technique, planting cover crops during the winter season is widely applied in the loess belt. Most of these cover crops freeze at the beginning of the winter period. Consequently, the above-ground biomass becomes less effective in protecting the soil from water erosion. Apart from the effects of the above-ground biomass in protecting the soil against raindrop impacts and reducing flow velocities by the retarding effects of their stems, plant roots also play an important role in improving soil strength. Previous research showed that roots contribute to a large extent to the resistance of topsoils against concentrated flow erosion. Unfortunately, information on root properties of common cover crops (e.g. Sinapis alba, Phacelia tanacetifoli, Lolium perenne, Avena sativa, Secale cereale, Raphanus sativus subsp. oleiferus) is very scarce. Therefore, root density distribution with depth and their erosion-reducing effects during concentrated flow erosion were assessed by conducting root auger measurements and concentrated flow experiments at the end of the growth period (December). The preliminary results indicate that the studied cover crops are not equally effective in preventing soil loss by concentrated flow erosion at the end of the growing season. Cover crops with thick roots, such as Sinapis alba and Raphanus sativus subsp. oleiferus are less effective than cover crops with fine-branched roots such as Phacelia tanacetifoli, Lolium perenne (Ryegrass), Avena sativa (Oats) and Secale cereale (Rye) in preventing soil losses by concentrated flow erosion. These results enable soil managers to select the most suitable crops and maximize soil protection.

Root distributions of Eurotia lanata in association with two species of agropyron on disturbed soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonham, C.D.; Mack, S.E.

1990-12-01

Root distributions of Eurotia lanata in association with Agropyron inerme and A. smithii on soils that were mechanically disturbed were studied. Root diagrams and measurements were made for plants in competitive pairs from soils representing two depths of soil disturbance (30 cm and 1 m) and control areas. Soil disturbance was observed to reduce significantly depth of root penetration and root concentration of E. lanata. Root depth, maximum lateral spread of roots, and zone of root concentration of E. lanata plants were greatest in pure stand pairs. Eurotia lanata associated with A. inerme had the smallest root concentration. The areamore » occupied by E. lanata roots was 59% greater in pure stands than when found adjacent to A. inerme. Agropyron inerme apparently used more available soil water in the top 20 cm of soil than did the shrub and resulted in reduced root growth for E. lanata. On the other hand, the asexual reproductive strategy of A. smithii, where roots and rhizomes were distributed both vertically and laterally, enables the grass species to minimize detrimental effects of its association with E. lanata. The results have important implications for selection of species combinations to reseed disturbed soils in semiarid or arid environments. In particular, attention should be given to use of species that have differing specializations as indicated by their growth and morphology.« less

Phytoextraction of Pb, Cr, Ni, and Zn using the aquatic plant Limnobium laevigatum and its potential use in the treatment of wastewater.

PubMed

Arán, Daniela Silvina; Harguinteguy, Carlos Alfredo; Fernandez-Cirelli, Alicia; Pignata, María Luisa

2017-08-01

In order to study the bioaccumulation of Pb, Cr, Ni, and Zn and the stress response, the floating aquatic plant Limnobium laevigatum was exposed to increasing concentrations of a mixture of these metals for 28 days, and its potential use in the treatment of wastewater was evaluated. The metal concentrations of the treatment 1 (T1) were Pb 1 μg L -1 , Cr 4 μg L -1 , Ni 25 μg L -1 , and Zn 30 μg L -1 ; of treatment 2 (T2) were Pb 70 μg L -1 , Cr 70 μg L -1 , Ni 70 μg L -1 , and Zn 70 μg L -1 ; and of treatment 3 (T3) were Pb 1000 μg L -1 , Cr 1000 μg L -1 , Ni 500 μg L -1 , and Zn 100 μg L -1 , and there was also a control group (without added metal). The accumulation of Pb, Cr, Ni, and Zn in roots was higher than in leaves of L. laevigatum, and the bioconcentration factor revealed that the concentrations of Ni and Zn in the leaf and root exceeded by over a thousand times the concentrations of those in the culture medium (2000 in leaf and 6800 in root for Ni; 3300 in leaf and 11,500 in root for Zn). Thus, this species can be considered as a hyperaccumulator of these metals. In general, the changes observed in the morphological and physiological parameters and the formation of products of lipid peroxidation of membranes during the exposure to moderate concentrations (T2) of the mixture of metals did not cause harmful effects to the survival of the species within the first 14 days of exposure. Taking into account the accumulation capacity and tolerance to heavy metals, L. laevigatum is suitable for phytoremediation in aquatic environments contaminated with moderated concentrations of Cr, Ni, Pb, and Zn in the early stages of exposure.

[Effects of culture conditions on biomass and active components of adventitious roots culture in Panax ginseng].

PubMed

Huang, Tao; Gao, Wenyuan; Wang, Juan; Cao, Yu

2010-01-01

To optimize the culture condition of adventitious roots of Panax ginseng. The adventitious roots were obtained through tissue culture by manipulation of inoculum, various sucrose concentrations and salt strength. The contents of ginsenosides Re, Rb1 and Rg1 were determined by HPLC while the contents of polysaccharides were determined by ultraviolet spectrophotometry. The multiplication of adventitious roots reached the peak when the inoculum was 20 g x L(-1). The effects of sucrose concentration and salt strength on adventitious roots were observed. The contents of polysaccharides were higher when the medium contained more sucrose. 40 g x L(-1) sucrose was favorable for roots growth and biosynthesis of Re, while 30 g x L(-1) was favorable for the biosynthesis of Rb1 and Rg1. 3/4MS medium was benefit for the growth of adventitious roots and the biosynthesis of ginsenosides. The contents of polysaccharides were decreased with the increase of salt strength. The results showed that inoculum, various sucrose concentrations and salt strength have significant influences on adventitious roots growth, secondary metabolite and polysaccharide synthesis in P. ginseng.

Phytoaccumulation of trace elements by wetland plants. 2: Water hyacinth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Y.L.; Zayed, A.M.; Qian, J.H.

Wetland plants are being used successfully for the phytoremediation of trace elements in natural and constructed wetlands. This study demonstrates the potential of water hyacinth (Eichhornia crassipes), an aquatic floating plant, for the phytoremediation of six trace elements. The ability of water hyacinth to take up and translocate six trace elements--As(V), Cd(II), Cr(VI), Cu(II), Ni(II), and Se(VI)--was studied under controlled conditions. Water hyacinth accumulated Cd and Cr best, Se and Cu at moderate levels, and was a poor accumulator of As and Ni. The highest levels of Cd found in shoots and roots were 371 and 6103 mg kg[sup [minus]1]more » dry wt., respectively, and those of Cr were 119 and 32951 mg kg[sup [minus]1] dry wt, respectively. Cadmium, Cr, Cu, Ni, and As were more highly accumulated in roots than in shoots. In contrast, Se was accumulated more in shoots than in roots at most external concentrations. Water hyacinth had high trace element bioconcentration factors when supplied with low external concentrations of all six elements, particularly Cd, Cr, and Cu. Therefore, water hyacinth will be very efficient at phytoextracting trace elements from wastewater containing low concentrations of these elements. The authors conclude that water hyacinth is a promising candidate for phytoremediation of wastewater polluted with Cd, Cr, Cu, and Se.« less

Biomarker discovery and gene expression responses in Lycopersicon esculentum root exposed to lead.

PubMed

Hou, Jing; Bai, Lili; Xie, Yujia; Liu, Xinhui; Cui, Baoshan

2015-12-15

Gene expression analysis has shown particular promise for the identification of molecular biomarkers that can be used for further evaluation of potential toxicity of chemicals present in agricultural soil. In the study, we focused on the development of molecular markers to detect Pb toxicity in agricultural soil. Using the results obtained from microarray analysis, twelve Pb-responsive genes were selected and tested in different Pb concentrations to examine their concentration-response characteristics using real-time quantitative polymerase chain reaction (RT-qPCR). All the Pb treatments set in our study could generally induce the differential expression of the 12 genes, while the lowest observable adverse effect concentration (LOAEC) of Pb for seed germination, root elongation, biomass and structural modification derived from 1,297, 177, 177, and 1,297 mg Pb/kg soil, respectively, suggesting that the transcriptional approach was more sensitive than the traditional end points of death, growth, and morphology for the evaluation of Pb toxicity. The relative expression of glycoalkaloid metabolism 1 (P=-0.790), ethylene-responsive transcription factor ERF017 (P=-0.686) and CASP-like protein 4C2 (P=-0.652) demonstrates a dose-dependent response with Pb content in roots, implying that the three genes can be used as sensitive bioindicators of Pb stress in Lycopersicon esculentum. Copyright © 2015 Elsevier B.V. All rights reserved.

Potential contributions of root decomposition to the nitrogen cycle in arctic forest and tundra.

PubMed

Träger, Sabrina; Milbau, Ann; Wilson, Scott D

2017-12-01

Plant contributions to the nitrogen (N) cycle from decomposition are likely to be altered by vegetation shifts associated with climate change. Roots account for the majority of soil organic matter input from vegetation, but little is known about differences between vegetation types in their root contributions to nutrient cycling. Here, we examine the potential contribution of fine roots to the N cycle in forest and tundra to gain insight into belowground consequences of the widely observed increase in woody vegetation that accompanies climate change in the Arctic. We combined measurements of root production from minirhizotron images with tissue analysis of roots from differing root diameter and color classes to obtain potential N input following decomposition. In addition, we tested for changes in N concentration of roots during early stages of decomposition, and investigated whether vegetation type (forest or tundra) affected changes in tissue N concentration during decomposition. For completeness, we also present respective measurements of leaves. The potential N input from roots was twofold greater in forest than in tundra, mainly due to greater root production in forest. Potential N input varied with root diameter and color, but this variation tended to be similar in forest and tundra. As for roots, the potential N input from leaves was significantly greater in forest than in tundra. Vegetation type had no effect on changes in root or leaf N concentration after 1 year of decomposition. Our results suggest that shifts in vegetation that accompany climate change in the Arctic will likely increase plant-associated potential N input both belowground and aboveground. In contrast, shifts in vegetation might not alter changes in tissue N concentration during early stages of decomposition. Overall, differences between forest and tundra in potential contribution of decomposing roots to the N cycle reinforce differences between habitats that occur for leaves.

Fluoride bioaccumulation by hydroponic cultures of camellia (Camellia japonica spp.) and sugar cane (Saccharum officinarum spp.).

PubMed

Camarena-Rangel, Nancy; Rojas Velázquez, Angel Natanael; Santos-Díaz, María del Socorro

2015-10-01

The ability of hydroponic cultures of camellia and sugar cane adult plants to remove fluoride was investigated. Plants were grown in a 50% Steiner nutrient solution. After an adaptation period to hydroponic conditions, plants were exposed to different fluoride concentrations (0, 2.5, 5 and 10 mg L(-1)). Fluoride concentration in the culture medium and in tissues was measured. In sugar cane, fluoride was mainly located in roots, with 86% of it absorbed and 14% adsorbed. Sugar cane plants removed 1000-1200 mg fluoride kg(-1) dry weight. In camellia plants the highest fluoride concentration was found in leaf. Roots accumulated fluoride mainly through absorption, which was 2-5 times higher than adsorption. At the end of the experiment, fluoride accumulation in camellia plants was 1000-1400 mgk g(-1) dry weight. Estimated concentration factors revealed that fluoride bioaccumulation is 74-221-fold in camellia plants and 100-500-fold in sugar cane plants. Thus, the latter appear as a suitable candidate for removing fluoride from water due to their bioaccumulation capacity and vigorous growth rate; therefore, sugar cane might be used for phytoremediation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Role of extrinsic arbuscular mycorrhizal fungi in heavy metal-contaminated wetlands with various soil moisture levels.

PubMed

Zheng, S; Wang, C; Shen, Z; Quan, Y; Liu, X

2015-01-01

This study presents an efficient heavy metal (HM) control method in HM-contaminated wetlands with varied soil moisture levels through the introduction of extrinsic arbuscular mycorrhizal fungi (AMF) into natural wetland soil containing indigenous AMF species. A pot culture experiment was designed to determine the effect of two soil water contents (5-8% and 25-30%), five extrinsic AMF inoculants (Glomus mosseae, G. clarum, G. claroideum, G. etunicatum, and G. intraradices), and HM contamination on root colonization, plant growth, and element uptake of common reed (Phragmites australis (Cav.) Trin. ex Steudel) plantlets in wetland soils. This study showed the prevalence of mycorrhizae in the roots of all P. australis plantlets, regardless of extrinsic AMF inoculations, varied soil moisture or HM levels. It seems that different extrinsic AMF inoculations effectively lowered HM concentrations in the aboveground tissues of P. australis at two soil moisture levels. However, metal species, metal concentrations, and soil moisture should also be very important factors influencing the elemental uptake performance of plants in wetland ecosystems. Besides, the soil moisture level significantly influenced plant growth (including height, and shoot and root dry weight (DW)), and extrinsic AMF inoculations differently affected shoot DW.

Root based responses account for Psidium guajava survival at high nickel concentration.

PubMed

Bazihizina, Nadia; Redwan, Mirvat; Taiti, Cosimo; Giordano, Cristiana; Monetti, Emanuela; Masi, Elisa; Azzarello, Elisa; Mancuso, Stefano

2015-02-01

The presence of Psidium guajava in polluted environments has been reported in recent studies, suggesting that this species has a high tolerance to the metal stress. The present study aims at a physiological characterization of P. guajava response to high nickel (Ni) concentrations in the root-zone. Three hydroponic experiments were carried out to characterize the effects of toxic Ni concentrations on morphological and physiological parameters of P. guajava, focusing on Ni-induced damages at the root-level and root ion fluxes. With up to 300μM NiSO4 in the root-zone, plant growth was similar to that in control plants, whereas at concentrations higher than 1000μM NiSO4 there was a progressive decline in plant growth and leaf gas exchange parameters; this occurred despite, at all considered concentrations, plants limited Ni(2+) translocation to the shoot, therefore avoiding shoot Ni(2+) toxicity symptoms. Maintenance of plant growth with 300μM Ni(2+) was associated with the ability to retain K(+) in the roots meanwhile 1000 and 3000μM NiSO4 led to substantial K(+) losses. In this study, root responses mirror all plant performances suggesting a direct link between root functionality and Ni(2+) tolerance mechanisms and plant survival. Considering that Ni was mainly accumulated in the root system, the potential use of P. guajava for Ni(2+) phytoextraction in metal-polluted soils is limited; nevertheless, the observed physiological changes indicate a good Ni(2+) tolerance up to 300μM NiSO4 suggesting a potential role for the phytostabilization of polluted soils. Copyright © 2014 Elsevier GmbH. All rights reserved.

Boron toxicity is alleviated by hydrogen sulfide in cucumber (Cucumis sativus L.) seedlings.

PubMed

Wang, Bao-Lan; Shi, Lei; Li, Yin-Xing; Zhang, Wen-Hao

2010-05-01

Boron (B) is an essential micronutrient for plants, which when occurs in excess in the growth medium, becomes toxic to plants. Rapid inhibition of root elongation is one of the most distinct symptoms of B toxicity. Hydrogen sulfide (H(2)S) is emerging as a potential messenger molecule involved in modulation of physiological processes in plants. In the present study, we investigated the role of H(2)S in B toxicity in cucumber (Cucumis sativus) seedlings. Root elongation was significantly inhibited by exposure of cucumber seedlings to solutions containing 5 mM B. The inhibitory effect of B on root elongation was substantially alleviated by treatment with H(2)S donor sodium hydrosulfide (NaHS). There was an increase in the activity of pectin methylesterase (PME) and up-regulated expression of genes encoding PME (CsPME) and expansin (CsExp) on exposure to high B concentration. The increase in PME activity and up-regulation of expression of CsPME and CsExp induced by high B concentration were markedly reduced in the presence of H(2)S donor. There was a rapid increase in soluble B concentrations in roots on exposure to high concentration B solutions. Treatment with H(2)S donor led to a transient reduction in soluble B concentration in roots such that no differences in soluble B concentrations in roots in the absence and presence of NaHS were found after 8 h exposure to the high concentration B solutions. These findings suggest that increases in activities of PME and expansin may underlie the inhibition of root elongation by toxic B, and that H(2)S plays an ameliorative role in protection of plants from B toxicity by counteracting B-induced up-regulation of cell wall-associated proteins of PME and expansins.

DRG axon elongation and growth cone collapse rate induced by Sema3A are differently dependent on NGF concentration.

PubMed

Kaselis, Andrius; Treinys, Rimantas; Vosyliūtė, Rūta; Šatkauskas, Saulius

2014-03-01

Regeneration of embryonic and adult dorsal root ganglion (DRG) sensory axons is highly impeded when they encounter neuronal growth cone-collapsing factor semaphorin3A (Sema3A). On the other hand, increasing evidence shows that DRG axon's regeneration can be stimulated by nerve growth factor (NGF). In this study, we aimed to evaluate whether increased NGF concentrations can counterweight Sema3A-induced inhibitory responses in 15-day-old mouse embryo (E15) DRG axons. The DRG explants were grown in Neurobasal-based medium with different NGF concentrations ranging from 0 to 100 ng/mL and then treated with Sema3A at constant 10 ng/mL concentration. To evaluate interplay between NGF and Sema3A number of DRG axons, axon outgrowth distance and collapse rate were measured. We found that the increased NGF concentrations abolish Sema3A-induced inhibitory effect on axon outgrowth, while they have no effect on Sema3A-induced collapse rate.

Production of the biopesticide azadirachtin by hairy root cultivation of Azadirachta indica in liquid-phase bioreactors.

PubMed

Srivastava, Smita; Srivastava, Ashok K

2013-11-01

Batch cultivation of Azadirachta indica hairy roots was carried out in different liquid-phase bioreactor configurations (stirred-tank, bubble column, bubble column with polypropylene basket, and polyurethane foam disc as root supports) to investigate possible scale-up of the A. indica hairy root culture for in vitro production of the biopesticide azadirachtin. The hairy roots failed to grow in the conventional bioreactor designs (stirred tank and bubble column). However, modified bubble column reactor (with polyurethane foam as root support) configuration facilitated high-density culture of A. indica hairy roots with a biomass production of 9.2 g l(-1)dry weight and azadirachtin yield of 3.2 mg g(-1) leading to a volumetric productivity of azadirachtin as 1.14 mg l(-1) day(-1). The antifeedant activity in the hairy roots was also evaluated by no choice feeding tests with known concentrations of the hairy root powder and its solvent extract separately on the desert locust Schistocerca gregaria. The hairy root powder and its solvent extract demonstrated a high level of antifeedant activity (with an antifeedant index of 97 % at a concentration of 2 % w/v and 83 % at a concentration of 0.05 % (w/v), respectively, in ethanol).

Biochemical and genetic analyses of N metabolism in maize testcross seedlings: 2. Roots.

PubMed

Silva, Ignacio Trucillo; Abbaraju, Hari Kishan R; Fallis, Lynne P; Liu, Hongjun; Lee, Michael; Dhugga, Kanwarpal S

2018-06-01

Intracellular factors differentially affected enzyme activities of N assimilation in the roots of maize testcrosses where alanine aminotransferase and glutamate synthase were the main enzymes regulating the levels of glutamate. N is a key macronutrient for plant growth and development. Breeding maize with improved efficiency in N use could help reduce environmental contamination as well as increase profitability for the farmers. Quantitative trait loci (QTL) mapping of traits related to N metabolism in the root tissue was undertaken in a maize testcross mapping population grown in hydroponic cultures. N concentration was negatively correlated with root and total dry mass. Neither the enzyme activities nor metabolites were appreciably correlated between the root and leaf tissues. Repeatability measures for most of the enzymes were lower than for dry mass. Weak negative correlations between most of the enzymes and dry mass resulted likely from dilution and suggested the presence of excess of enzyme activities for maximal biomass production. Glutamate synthase and alanine aminotransferase each explained more variation in glutamate concentration than either aspartate aminotransferase or asparagine synthetase whereas glutamine synthetase was inconsequential. Twenty-six QTL were identified across all traits. QTL models explained 7-43% of the variance with no significant epistasis between the QTL. Thirteen candidate genes were identified underlying QTL within 1-LOD confidence intervals. All the candidate genes were located in trans configuration, unlinked or even on different chromosomes, relative to the known genomic positions of the corresponding structural genes. Our results have implications in improving NUE in maize and other crop plants.

Jasmonate signaling is activated in the very early stages of iron deficiency responses in rice roots.

PubMed

Kobayashi, Takanori; Itai, Reiko Nakanishi; Senoura, Takeshi; Oikawa, Takaya; Ishimaru, Yasuhiro; Ueda, Minoru; Nakanishi, Hiromi; Nishizawa, Naoko K

2016-07-01

Under low iron availability, plants induce the expression of various genes involved in iron uptake and translocation at the transcriptional level. This iron deficiency response is affected by various plant hormones, but the roles of jasmonates in this response are not well-known. We investigated the involvement of jasmonates in rice iron deficiency responses. High rates of jasmonate-inducible genes were induced during the very early stages of iron deficiency treatment in rice roots. Many jasmonate-inducible genes were also negatively regulated by the ubiquitin ligases OsHRZ1 and OsHRZ2 and positively regulated by the transcription factor IDEF1. Ten out of 35 genes involved in jasmonate biosynthesis and signaling were rapidly induced at 3 h of iron deficiency treatment, and this induction preceded that of known iron deficiency-inducible genes involved in iron uptake and translocation. Twelve genes involved in jasmonate biosynthesis and signaling were also upregulated in HRZ-knockdown roots. Endogenous concentrations of jasmonic acid and jasmonoyl isoleucine tended to be rapidly increased in roots in response to iron deficiency treatment, whereas these concentrations were higher in HRZ-knockdown roots under iron-sufficient conditions. Analysis of the jasmonate-deficient cpm2 mutant revealed that jasmonates repress the expression of many iron deficiency-inducible genes involved in iron uptake and translocation under iron sufficiency, but this repression is partly canceled under an early stage of iron deficiency. These results indicate that jasmonate signaling is activated during the very early stages of iron deficiency, which is partly regulated by IDEF1 and OsHRZs.

Response to non-uniform salinity in the root zone of the halophyte Atriplex nummularia: growth, photosynthesis, water relations and tissue ion concentrations.

PubMed

Bazihizina, Nadia; Colmer, Timothy D; Barrett-Lennard, Edward G

2009-09-01

Soil salinity is often heterogeneous, yet the physiology of halophytes has typically been studied with uniform salinity treatments. An evaluation was made of the growth, net photosynthesis, water use, water relations and tissue ions in the halophytic shrub Atriplex nummularia in response to non-uniform NaCl concentrations in a split-root system. Atriplex nummularia was grown in a split-root system for 21 d, with either the same or two different NaCl concentrations (ranging from 10 to 670 mm), in aerated nutrient solution bathing each root half. Non-uniform salinity, with high NaCl in one root half (up to 670 mm) and 10 mm in the other half, had no effect on shoot ethanol-insoluble dry mass, net photosynthesis or shoot pre-dawn water potential. In contrast, a modest effect occurred for leaf osmotic potential (up to 30 % more solutes compared with uniform 10 mm NaCl treatment). With non-uniform NaCl concentrations (10/670 mm), 90 % of water was absorbed from the low salinity side, and the reduction in water use from the high salinity side caused whole-plant water use to decrease by about 30 %; there was no compensatory water uptake from the low salinity side. Leaf Na(+) and Cl(-) concentrations were 1.9- to 2.3-fold higher in the uniform 670 mm treatment than in the 10/670 mm treatment, whereas leaf K(+) concentrations were 1.2- to 2.0-fold higher in the non-uniform treatment. Atriplex nummularia with one root half in 10 mm NaCl maintained net photosynthesis, shoot growth and shoot water potential even when the other root half was exposed to 670 mm NaCl, a concentration that inhibits growth by 65 % when uniform in the root zone. Given the likelihood of non-uniform salinity in many field situations, this situation would presumably benefit halophyte growth and physiology in saline environments.

Uranium accumulation in aquatic macrophytes in an uraniferous region: Relevance to natural attenuation.

PubMed

Cordeiro, Cristina; Favas, Paulo J C; Pratas, João; Sarkar, Santosh Kumar; Venkatachalam, Perumal

2016-08-01

Phytoremediation potential of uranium (U) was investigated by submerged, free-floating and rooted emergent native aquatic macrophytes inhabiting along the streams of Horta da Vilariça, a uraniferous geochemical region of NE Portugal. The work has been undertaken with the following objectives: (i) to relate the U concentrations in water-sediment-plant system; and (ii) to identify the potentialities of aquatic plants to remediate U-contaminated waters based on accumulation pattern. A total of 25 plant species culminating 233 samples was collected from 15 study points along with surface water and contiguous sediments. Concentrations of U showed wide range of variations both in waters (0.61-5.56 μg L(-1), mean value 1.98 μg L(-1)) and sediments (124-23,910 μg kg(-1), mean value 3929 μg kg(-1)) and this is also reflected in plant species examined. The plant species exhibited the ability to accumulate U several orders of magnitude higher than the surrounding water. Maximum U concentrations was recorded in the bryophyte Scorpiurium deflexifolium (49,639 μg kg(-1)) followed by Fontinalis antipyretica (35,771 μg kg(-1)), shoots of Rorippa sylvestris (33,837 μg kg(-1)), roots of Oenanthe crocata (17,807 μg kg(-1)) as well as in Nasturtium officinale (10,995 μg kg(-1)). Scorpiurium deflexifolium displayed a high bioconcentration factor (BF) of ∼2.5 × 10(4) (mean value). The species Fontinalis antipyretica, Nasturtium officinale (roots) and Rorippa sylvestris (shoots) exhibited the mean BFs of 1.7 × 10(4), 5 × 10(3) and 4.8 × 10(3) respectively. Maximum translocation factor (TF) was very much pronounced in the rooted perennial herb Rorippa sylvestris showing extreme ability to transport U for the shoots and seems to be promising candidate to be used as bioindicator species. Copyright © 2016 Elsevier Ltd. All rights reserved.

Differential bioaccumulation and translocation patterns in three mangrove plants experimentally exposed to iron. Consequences for environmental sensing.

PubMed

Arrivabene, Hiulana Pereira; Campos, Caroline Quenupe; Souza, Iara da Costa; Wunderlin, Daniel Alberto; Milanez, Camilla Rozindo Dias; Machado, Silvia Rodrigues

2016-08-01

Avicennia schaueriana, Laguncularia racemosa and Rhizophora mangle were experimentally exposed to increasing levels of iron (0, 10, 20 and 100 mg L(-1) added Fe(II) in Hoagland's nutritive medium). The uptake and translocation of iron from roots to stems and leaves, Fe-secretion through salt glands (Avicennia schaueriana and Laguncularia racemosa) as well as anatomical and histochemical changes in plant tissues were evaluated. The main goal of this work was to assess the diverse capacity of these plants to detect mangroves at risk in an area affected by iron pollution (Vitoria, Espírito Santo, Brazil). Results show that plants have differential patterns with respect to bioaccumulation, translocation and secretion of iron through salt glands. L. racemosa showed the best environmental sensing capacity since the bioaccumulation of iron in both Fe-plaque and roots was higher and increased as the amount of added-iron rose. Fewer changes in translocation factors throughout increasing added-iron were observed in this species. Furthermore, the amount of iron secreted through salt glands of L. racemosa was strongly inhibited when exposed to added-iron. Among three studied species, A. schaueriana showed the highest levels of iron in stems and leaves. On the other hand, Rhizophora mangle presented low values of iron in these compartments. Even so, there was a significant drop in the translocation factor between aerial parts with respect to roots, since the bioaccumulation in plaque and roots of R. mangle increased as iron concentration rose. Moreover, rhizophores of R. mangle did not show changes in bioaccumulation throughout the studied concentrations. So far, we propose L. racemosa as the best species for monitoring iron pollution in affected mangroves areas. To our knowledge, this is the first detailed report on the response of these plants to increasing iron concentration under controlled conditions, complementing existing data on the behavior of the same plants under field exposure. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of development, postharvest handling, and storage conditions on the carbohydrate components of sweetpotato (Ipomea batatas Lam.) roots.

PubMed

Nabubuya, Agnes; Namutebi, Agnes; Byaruhanga, Yusuf; Narvhus, Judith; Wicklund, Trude

2017-11-01

Changes in total starch and reducing sugar content in five sweetpotato varieties were investigated weekly during root development and following subjection of the roots to different postharvest handling and storage conditions. Freshly harvested (noncured) roots and cured roots (spread under the sun for 4 days at 29-31°C and 63-65% relative humidity [RH]) were separately stored at ambient conditions (23°C-26°C and 70-80% RH) and in a semiunderground pit (19-21°C and 90-95% RH). Changes in pasting properties of flour from sweetpotato roots during storage were analyzed at 14-day intervals. Significant varietal differences ( p  < .05) in total starch, sucrose, glucose, maltose, and fructose concentrations were registered. The total starch and sucrose content of the roots did not change significantly ( p  < .05) during root development (72.4 and 7.4%, respectively), whereas the average concentrations of glucose, maltose, and fructose decreased markedly (0.46-0.18%, 0.55-0.28%, and 0.43-0.21%), respectively. Storage led to decrease in total starch content (73-47.7%) and increase in sucrose and glucose concentrations (8.1-11.2% and 0.22-1.57%, respectively). Storage also resulted in reduction in sweetpotato flour pasting viscosities. Curing resulted in increased sucrose and glucose concentrations (9.1-11.2% and 0.45-0.85%, respectively) and marked reduction ( p  < .05) in total starch content (72.9-47.6%). This resulted in low pasting viscosities compared to flour from storage of uncured roots. These findings show that significant changes occur in the carbohydrate components of sweetpotato roots during storage compared to development and present an opportunity for diverse utilization of flours from sweetpotato roots in the food industry.

Polynuclear aromatic hydrocarbon uptake by carrots grown in sludge-amended soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wild, S.R.; Jones, K.C.

The uptake of polynuclear aromatic hydrocarbons (PAHs) from sewage sludge-amended soils by carrots (Daucus carota) was investigated. Carrots were grown in control soils and soils amended with three sludge application rates, 15, 55, and 180 t/ha. Applied sludge contained 17.2 mg [summation]PAH/kg, a concentration typical for a sludge derived from a rural area. Carrot foliage, root peels and root cores were analyzed for 15 PAH compounds. Carrots foliage PAH concentrations were unaffected by sludge applications (PAH loadings), but root peel PAH concentrations increased to a plateau concentration with increasing soil PAH levels. Low molecular weight PAH compounds dominate dindividual componentsmore » of the [summation]PAH load in the root tissues. The PAH concentrations detected in the root peels were all significantly lower than in the foliage, which receives PAH inputs from the atmosphere. Carrot core [summation]PAH concentrations were unaffected by sludge application, implying little or no transfer of PAHs from the peels to the core. About 70% of the PAH burden found in carrots was associated with the peels. Fresh weight carrot core concentrations were all <4.2 [mu]g/kg. Overall, this investigation suggests that the risks posed to human health by PAHs applied in sewage sludge to arable soils are minimal.« less

Phytoremediation of heavy metal copper (Cu2+) by sunflower (Helianthus annuus l.)

NASA Astrophysics Data System (ADS)

Mahardika, G.; Rinanti, A.; Fachrul, M. F.

2018-01-01

A study in microcosmic condition has been carried out to determine the effectiveness of Helianthus annuus as a hyperaccumulator plant for heavy metal, Copper (Cu2+), that exposed in the soil. Artificial pollutants containing Copper (Cu2+) 0, 60, 120, 180 ppm are exposed to uncontaminated soil. The 12-weeks old H. annuus seedling were grown in Cu2+ contaminated soil, with variations of absorption time 3, 6, and 9 weeks. Analysis of Cu2+ concentration on soil and H. annuus (root, stem, leaf) was analised by Atomic Absorbtion Spectrometry (AAS). H. annuus are capable for Cu2+ removal, and the highest removal of Cu2+ is 85.56%, the highest metal accumulation/bioconcentration factor (BCF) is 0.99 occurred at roots with 9 weeks of exposure time and the highest translocation factor (TF) is 0.71. This highest removal is five times better than absorption by stems and leaves. The results concluded, the use of H. annuus for phytoextraction of heavy metals Cu2+ in contaminated soil can be an alternative to the absorption of heavy metal Cu2+ with low concentration metals which is generally very difficult to do in physical-chemical removal.

Salt stress signals shape the plant root.

PubMed

Galvan-Ampudia, Carlos S; Testerink, Christa

2011-06-01

Plants use different strategies to deal with high soil salinity. One strategy is activation of pathways that allow the plant to export or compartmentalise salt. Relying on their phenotypic plasticity, plants can also adjust their root system architecture (RSA) and the direction of root growth to avoid locally high salt concentrations. Here, we highlight RSA responses to salt and osmotic stress and the underlying mechanisms. A model is presented that describes how salinity affects auxin distribution in the root. Possible intracellular signalling pathways linking salinity to root development and direction of root growth are discussed. These involve perception of high cytosolic Na+ concentrations in the root, activation of lipid signalling and protein kinase activity and modulation of endocytic pathways. Copyright © 2011 Elsevier Ltd. All rights reserved.

Uptake and Accumulation of the Herbicides Chlorsulfuron and Clopyralid in Excised Pea Root Tissue 1

PubMed Central

Devine, Malcolm D.; Bestman, Hank D.; Vanden Born, William H.

1987-01-01

The herbicides chlorsulfuron and clopyralid were taken up rapidly by excised pea root tissue and accumulated in the tissue to concentrations ten and four times those in the external medium, respectively. Uptake was related linearly to external herbicide concentration over a wide concentration range, implying that transport across the membrane is by nonfacilitated diffusion. Uptake of both compounds was influenced by pH, with greatest uptake at low pH. The pH dependence of uptake suggests that the herbicides (both of which are weak acids) are transported across the plasma membrane in the undissociated form, and accumulate in the cytoplasm by an ion trap mechanism. Most of the absorbed herbicide effluxed from the tissue when it was transferred to herbicide-free buffer, indicating that the accumulation was not due to irreversible binding. Consequently, both herbicides remain available for transfer to the phloem. These results can explain the high reported phloem mobility of clopyralid in intact plants. The low phloem mobility of chlorsulfuron must be accounted for by factors that override its ability to accumulate in the symplast. PMID:16665689

Local and distal effects of arbuscular mycorrhizal colonization on direct pathway Pi uptake and root growth in Medicago truncatula

PubMed Central

Watts-Williams, Stephanie J.; Jakobsen, Iver; Cavagnaro, Timothy R.; Grønlund, Mette

2015-01-01

Two pathways exist for plant Pi uptake from soil: via root epidermal cells (direct pathway) or via associations with arbuscular mycorrhizal (AM) fungi, and the two pathways interact in a complex manner. This study investigated distal and local effects of AM colonization on direct root Pi uptake and root growth, at different soil P levels. Medicago truncatula was grown at three soil P levels in split-pots with or without AM fungal inoculation and where one root half grew into soil labelled with 33P. Plant genotypes included the A17 wild type and the mtpt4 mutant. The mtpt4 mutant, colonized by AM fungi, but with no functional mycorrhizal pathway for Pi uptake, was included to better understand effects of AM colonization per se. Colonization by AM fungi decreased expression of direct Pi transporter genes locally, but not distally in the wild type. In mtpt4 mutant plants, direct Pi transporter genes and the Pi starvation-induced gene Mt4 were more highly expressed than in wild-type roots. In wild-type plants, less Pi was taken up via the direct pathway by non-colonized roots when the other root half was colonized by AM fungi, compared with non-mycorrhizal plants. Colonization by AM fungi strongly influenced root growth locally and distally, and direct root Pi uptake activity locally, but had only a weak influence on distal direct pathway activity. The responses to AM colonization in the mtpt4 mutant suggested that in the wild type, the increased P concentration of colonized roots was a major factor driving the effects of AM colonization on direct root Pi uptake. PMID:25944927

Growth and antioxidant defense responses of wheat seedlings to di-n-butyl phthalate and di (2-ethylhexyl) phthalate stress.

PubMed

Gao, Minling; Dong, Youming; Zhang, Ze; Song, Wenhua; Qi, Yun

2017-04-01

Phthalate acid esters (PAEs) are vital environmental hormone-like chemicals that are noxious to plants, animals, and human beings. In this study, the influences of di-n-butyl phthalate (DBP) and di (2-ethylhexyl) phthalate (DEHP) on the seed germination, root morphology, and various physiological changes of wheat seedlings were investigated by analyzing superoxide anion (O 2 - ) accumulation, antioxidant enzyme activity, and lipid peroxidation. DBP and DEHP were found to obviously inhibit germination only at high concentrations, but significantly affected root morphology even at lower concentrations. Their toxic effects were the most severe on root elongation, followed by shoot elongation, and were the least severe on germination rate, indicating that root elongation was the best index for evaluating DBP and DEHP eco-toxicity. DBP and DEHP also enhanced O 2 - and malondialdehyde levels and membrane permeability, as well as produced changes in the antioxidant status and PAE content in the stem and leaf (combined tissues, hereafter shoot) and root tissues. The activities of superoxide dismutase, catalase, and peroxidase increased at low and medium DBP and DEHP concentrations, but declined at high PAE concentrations. These results indicated that PAEs could exert oxidative damage in the early development stage of wheat, particularly at higher concentrations. DBP and DEHP accumulation was higher in the roots than in the shoot tissues, and their levels in these tissues increased with increasing PAE concentrations, supporting their more-serious toxic effects on roots than those on shoots. Further, the physicochemical properties of DBP rendered it more harmful than DEHP. Copyright © 2017 Elsevier Ltd. All rights reserved.

Low humic acids promote in vitro lily bulblet enlargement by enhancing roots growth and carbohydrate metabolism * #

PubMed Central

Wu, Yun; Xia, Yi-ping; Zhang, Jia-ping; Du, Fang; Zhang, Lin; Ma, Yi-di; Zhou, Hong

2016-01-01

Bulblet development is a problem in global lily bulb production and carbohydrate metabolism is a crucial factor. Micropropagation acts as an efficient substitute for faster propagation and can provide a controllable condition to explore bulb growth. The present study was conducted to investigate the effects of humic acid (HA) on bulblet swelling and the carbohydrate metabolic pathway in Lilium Oriental Hybrids ‘Sorbonne’ under in vitro conditions. HA greatly promoted bulblet growth at 0.2, 2.0, and 20.0 mg/L, and pronounced increases in bulblet sucrose, total soluble sugar, and starch content were observed for higher HA concentrations (≥2.0 mg/L) within 45 d after transplanting (DAT). The activities of three major starch synthetic enzymes (including adenosine 5'-diphosphate glucose pyrophosphorylase, granule-bound starch synthase, and soluble starch synthase) were enhanced dramatically after HA application especially low concentration HA (LHA), indicating a quick response of starch metabolism. However, higher doses of HA also caused excessive aboveground biomass accumulation and inhibited root growth. Accordingly, an earlier carbon starvation emerged by observing evident starch degradation. Relative bulblet weight gradually decreased with increased HA doses and thereby broke the balance between the source and sink. A low HA concentration at 0.2 mg/L performed best in both root and bulblet growth. The number of roots and root length peaked at 14.5 and 5.75 cm, respectively. The fresh bulblet weight and diameter reached 468 mg (2.9 times that under the control treatment) and 11.68 mm, respectively. Further, sucrose/starch utilization and conversion were accelerated and carbon famine was delayed as a result with an average relative bulblet weight of 80.09%. To our knowledge, this is the first HA application and mechanism research into starch metabolism in both in vitro and in vivo condition in bulbous crops. PMID:27819136

Low humic acids promote in vitro lily bulblet enlargement by enhancing roots growth and carbohydrate metabolism.

PubMed

Wu, Yun; Xia, Yi-Ping; Zhang, Jia-Ping; Du, Fang; Zhang, Lin; Ma, Yi-di; Zhou, Hong

Bulblet development is a problem in global lily bulb production and carbohydrate metabolism is a crucial factor. Micropropagation acts as an efficient substitute for faster propagation and can provide a controllable condition to explore bulb growth. The present study was conducted to investigate the effects of humic acid (HA) on bulblet swelling and the carbohydrate metabolic pathway in Lilium Oriental Hybrids 'Sorbonne' under in vitro conditions. HA greatly promoted bulblet growth at 0.2, 2.0, and 20.0 mg/L, and pronounced increases in bulblet sucrose, total soluble sugar, and starch content were observed for higher HA concentrations (≥2.0 mg/L) within 45 d after transplanting (DAT). The activities of three major starch synthetic enzymes (including adenosine 5'-diphosphate glucose pyrophosphorylase, granule-bound starch synthase, and soluble starch synthase) were enhanced dramatically after HA application especially low concentration HA (LHA), indicating a quick response of starch metabolism. However, higher doses of HA also caused excessive aboveground biomass accumulation and inhibited root growth. Accordingly, an earlier carbon starvation emerged by observing evident starch degradation. Relative bulblet weight gradually decreased with increased HA doses and thereby broke the balance between the source and sink. A low HA concentration at 0.2 mg/L performed best in both root and bulblet growth. The number of roots and root length peaked at 14.5 and 5.75 cm, respectively. The fresh bulblet weight and diameter reached 468 mg (2.9 times that under the control treatment) and 11.68 mm, respectively. Further, sucrose/starch utilization and conversion were accelerated and carbon famine was delayed as a result with an average relative bulblet weight of 80.09%. To our knowledge, this is the first HA application and mechanism research into starch metabolism in both in vitro and in vivo condition in bulbous crops.

Mechanisms for the increase in phosphorus uptake of waterlogged plants: soil phosphorus availability, root morphology and uptake kinetics.

PubMed

Rubio, Gerardo; Oesterheld, Martín; Alvarez, Carina R; Lavado, Raúl S

1997-10-01

Waterlogging frequently reduces plant biomass allocation to roots. This response may result in a variety of alterations in mineral nutrition, which range from a proportional lowering of whole-plant nutrient concentration as a result of unchanged uptake per unit of root biomass, to a maintenance of nutrient concentration by means of an increase in uptake per unit of root biomass. The first objective of this paper was to test these two alternative hypothetical responses. In a pot experiment, we evaluated how plant P concentration of Paspalum dilatatum, (a waterlogging-tolerant grass from the Flooding Pampa, Argentina) was affected by waterlogging and P supply and how this related to changes in root-shoot ratio. Under both soil P levels waterlogging reduced root-shoot ratios, but did not reduce P concentration. Thus, uptake of P per unit of root biomass increased under waterlogging. Our second objective was to test three non-exclusive hypotheses about potential mechanisms for this increase in P uptake. We hypothesized that the greater P uptake per unit of root biomass was a consequence of: (1) an increase in soil P availability induced by waterlogging; (2) a change in root morphology, and/or (3) an increase in the intrinsic uptake capacity of each unit of root biomass. To test these hypotheses we evaluated (1) changes in P availability induced by waterlogging; (2) specific root length of waterlogged and control plants, and (3) P uptake kinetics in excised roots from waterlogged and control plants. The results supported the three hypotheses. Soil P avail-ability was higher during waterlogging periods, roots of waterlogged plants showed a morphology more favorable to nutrient uptake (finer roots) and these roots showed a higher physiological capacity to absorb P. The results suggest that both soil and plant mechanisms contributed to compensate, in terms of P nutrition, for the reduction in allocation to root growth. The rapid transformation of the P uptake system is likely an advantage for plants inhabiting frequently flooded environments with low P fertility, like the Flooding Pampa. This advantage would be one of the reasons for the increased relative abundance of P. dilatatum in the community after waterlogging periods.

Effects of perchlorate on growth of four wetland plants and its accumulation in plant tissues.

PubMed

He, Hongzhi; Gao, Haishuo; Chen, Guikui; Li, Huashou; Lin, Hai; Shu, Zhenzhen

2013-10-01

Perchlorate contamination in water is of concern because of uncertainties about toxicity and health effects, impact on ecosystems, and possible indirect exposure pathways to humans. Therefore, it is very important to investigate the ecotoxicology of perchlorate and to screen plant species for phytoremediation. Effects of perchlorate (20, 200, and 500 mg/L) on the growth of four wetland plants (Eichhornia crassipes, Acorus calamus L., Thalia dealbata, and Canna indica) as well as its accumulation in different plant tissues were investigated through water culture experiments. Twenty milligrams per liter of perchlorate had no significant effects on height, root length, aboveground part weight, root weight, and oxidizing power of roots of four plants, except A. calamus, and increasing concentrations of perchlorate showed that out of the four wetland plants, only A. calamus had a significant (p<0.05) dose-dependent decrease in these parameters. When treated with 500 mg/L perchlorate, these parameters and chlorophyll content in the leaf of plants showed significant decline contrasted to control groups, except the root length of E. crassipes and C. indica. The order of inhibition rates of perchlorate on root length, aboveground part weight and root weight, and oxidizing power of roots was: A. calamus > C. indica > T. dealbata > E. crassipes and on chlorophyll content in the leaf it was: A. calamus > T. dealbata > C. indica > E. crassipes. The higher the concentration of perchlorate used, the higher the amount of perchlorate accumulation in plants. Perchlorate accumulation in aboveground tissues was much higher than that in underground tissues and leaf was the main tissue for perchlorate accumulation. The order of perchlorate accumulation content and the bioconcentration factor in leaf of four plants was: E. crassipes > C. indica > T. dealbata > A. calamus. Therefore, E. crassipes might be an ideal plant with high tolerance ability and accumulation ability for constructing wetland to remediate high levels of perchlorate polluted water.

Optimizing neurotrophic factor combinations for neurite outgrowth

NASA Astrophysics Data System (ADS)

Deister, C.; Schmidt, C. E.

2006-06-01

Most neurotrophic factors are members of one of three families: the neurotrophins, the glial cell-line derived neurotrophic factor family ligands (GFLs) and the neuropoietic cytokines. Each family activates distinct but overlapping cellular pathways. Several studies have shown additive or synergistic interactions between neurotrophic factors from different families, though generally only a single combination has been studied. Because of possible interactions between the neurotrophic factors, the optimum concentration of a factor in a mixture may differ from the optimum when applied individually. Additionally, the effect of combinations of neurotrophic factors from each of the three families on neurite extension is unclear. This study examines the effects of several combinations of the neurotrophin nerve growth factor (NGF), the GFL glial cell-line derived neurotrophic factor (GDNF) and the neuropoietic cytokine ciliary neurotrophic factor (CNTF) on neurite outgrowth from young rat dorsal root ganglion (DRG) explants. The combination of 50 ng ml-1 NGF and 10 ng ml-1 of each GDNF and CNTF induced the highest level of neurite outgrowth at a 752 ± 53% increase over untreated DRGs and increased the longest neurite length to 2031 ± 97 µm compared to 916 ± 64 µm for untreated DRGs. The optimum concentrations of the three factors applied in combination corresponded to the optimum concentration of each factor when applied individually. These results indicate that the efficacy of future therapies for nerve repair would be enhanced by the controlled release of a combination of neurotrophins, GFLs and neuropoietic cytokines at higher concentrations than used in previous conduit designs.

Platelet inhibitory effects of juices from Pachyrhizus erosus L. root and Psidium guajava L. fruit: a randomized controlled trial in healthy volunteers.

PubMed

Thaptimthong, Thitiporn; Kasemsuk, Thitima; Sibmooh, Nathawut; Unchern, Supeenun

2016-08-03

The purpose of this study is to investigate cardiovascular benefits of juices obtained from two commonly consumed fruits in Thailand, Pachyrhizus erosus, L. (yam bean) and Psidium guajava, L. (guava), by examining their acute cardiovascular effects in healthy volunteers. Possible involvements of the dietary nitrate on their effects were investigated as well. Thirty healthy volunteers were randomly divided into three groups of 10 subjects per group and each group was allocated to drink 500 ml of freshly prepared yam bean root juice, guava fruit juice, or water. Systemic nitrate and nitrite concentrations, heart rate, systolic and diastolic blood pressure, serum K(+) concentrations, ex vivo platelet aggregation, and plasma cGMP concentrations were monitored at the baseline and at various time points after the intake of juices or water. Data were compared by repeated measures ANOVA. Following the ingestion of both yam bean root juice and guava fruit juice, collagen-induced but not ADP-induced platelet aggregation was attenuated. Ingestion of yam bean root juice increased systemic nitrate and nitrite concentrations whereby elevated nitrite concentrations correlated with the extent of inhibiting collagen-induced platelet aggregation. In addition, positive correlation between systemic nitrite and plasma cGMP concentrations and negative correlation between plasma cGMP concentrations and the extent of collagen-induced platelet aggregation were revealed. Nevertheless, yam bean root juice reduced only diastolic blood pressure while guava fruit juice reduced heart rate, systolic and diastolic blood pressure. The present study has illustrated, for the first time, acute inhibitory effects of yam bean root juice and guava fruit juice on ex vivo collagen-induced platelet aggregation in healthy subjects. Dietary nitrate was shown to underlie the effect of yam bean root juice but not that of guava fruit juice. Following yam bean root juice ingestion, systemic nitrate apparently converts to nitrite and further to NO which may attenuate platelet responses to collagen stimulation. Cardiovascular benefits of juices from yam bean root and guava fruit are noteworthy in term of the cardiovascular health-promoting approach. Randomized controlled trial TCTR20150228001 .

External apical root resorption in maxillary incisors in orthodontic patients: associated factors and radiographic evaluation.

PubMed

Nanekrungsan, Kamonporn; Patanaporn, Virush; Janhom, Apirum; Korwanich, Narumanus

2012-09-01

This study was performed to evaluate the incidence and degree of external apical root resorption of maxillary incisors after orthodontic treatment and to evaluate particular associated factors related to external apical root resorption. The records and maxillary incisor periapical radiographs of 181 patients were investigated. Crown and root lengths were measured and compared on the pre- and post-treatment periapical radiographs. Crown length was measured from the center of the incisal edge to the midpoint of the cemento-enamel junction (CEJ). Root length was measured from the CEJ midpoint to the root apex. A correction factor for the enlargement difference was used to calculate root resorption. The periapical radiographs of 564 teeth showed that the average root resorption was 1.39±1.27 (8.24±7.22%) and 1.69±1.14 mm (10.16±6.78%) for the maxillary central and lateral incisors, respectively. The results showed that the dilacerated or pointed roots, maxillary premolar extraction cases, and treatment duration were highly significant factors for root resorption (p<0.001). Allergic condition was a significant factor at p<0.01. Age at the start of treatment, large overjet, and history of facial trauma were also factors significantly associated with root resorption (p<0.05). There was no statistically significant difference in root resorption among the factors of gender, overbite, tongue-thrusting habit, types of malocclusion, and types of bracket. These results suggested that orthodontic treatment should be carefully performed in pre-treatment extraction patients who have pointed or dilacerated roots and need long treatment duration.

The partial root-zone saline irrigation system and antioxidant responses in tomato plants.

PubMed

Alves, Rita de Cássia; de Medeiros, Ana Santana; Nicolau, Mayara Cristina Malvas; Neto, Antônio Pizolato; de Assis Oliveira, Francisco; Lima, Leonardo Warzea; Tezotto, Tiago; Gratão, Priscila Lupino

2018-06-01

Salinity is a limiting factor that can affect plant growth and cause significant losses in agricultural productivity. This study provides an insight about the viability of partial root-zone irrigation (PRI) system with saline water supported by a biochemical approach involving antioxidant responses. Six different irrigation methods using low and high salt concentrations (S1-0.5 and S2-5.0 dS m -1 ) were applied, with or without PRSI, so that one side of the root-zone was submitted to saline water while the other side was low salinity water irrigated. The results revealed different responses according to the treatments and the PRSI system applied. For the treatments T1, T2 and T3, the PRSI was not applied, while T4, T5 and T6 treatments were applied with PRSI system. Lipid peroxidation, proline content, and activities of SOD, CAT, APX, GR and GSH in tomato plants subjected to PRSI system were analyzed. Plant growth was not affected by the salt concentrations; however, plants submitted to high salt concentrations showed high MDA content and Na + accumulation when compared to the control plants. Plants submitted to treatments T4, T5 and T6 with PRSI system exhibited lower MDA compared to the control plants (T1). Proline content and activities of SOD, CAT, APX, GR and GSH content were maintained in all treatments and tissues analyzed, with only exception for APX in fruits and GSH content, in roots. The overall results showed that PRSI system could be an applicable technique for saline water supply on irrigation since plants did not show to be vulnerable to salt stress, supported by a biochemical approach involving antioxidant responses. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

The Tennessee study: factors affecting treatment outcome and healing time following nonsurgical root canal treatment.

PubMed

Azim, A A; Griggs, J A; Huang, G T-J

2016-01-01

To determine factors that may influence treatment outcome and healing time following root canal treatment. Root filled and restored teeth by pre-doctoral students were included in this study. Teeth/roots were followed-up regularly, and treatment outcome was evaluated at every follow-up appointment (healed, healing, uncertain or unsatisfactory). Host (age, immune condition, pulp/periapical diagnosis, tooth/root type, location and anatomy) and treatment factors (master apical file size, apical extension, voids and density of root filling) were recorded from patient dental records. Univariate, bivariate and multivariate analyses were performed to determine the impact of the factors on treatment outcomes and healing times. A total of 422 roots from 291 teeth met the inclusion criteria with a mean follow-up period of 2 years. The preoperative pulp condition, procedural errors during treatment, apical extension and density of root fillings significantly affected the treatment outcome. The average time required for a periapical lesion to heal was 11.78 months. The healing time increased in patients with compromised healing, patients older than 40 years, roots with Weine type II root canal systems, root canal systems prepared to a master apical file size <35, and roots with overextended fillings (P < 0.1). Multiple host and treatment factors affected the healing time and outcome of root canal treatment. Follow-up protocols should consider these factors before concluding the treatment outcome: patient's age, immune condition, as well as roots with overextended fillings, root canal systems with smaller apical preparations (size <35) or roots with complex canal systems. Intervention may be recommended if the treatment quality was inadequate or if patients became symptomatic. © 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Soil-to-cassava transfer of naturally occurring radionuclides from communities along Ghana's oil and gas rich Tano Basin.

PubMed

Doyi, Israel Nutifafa Yawo; Essumang, David Kofi; Agyapong, Asare Kwaku; Asumadu-Sarkodie, Samuel

2018-02-01

Soil-to-plant transfer factor (TF) is widely used to assess the impact of soil radioactivity on agricultural crops. The root crop cassava (Manihot esculenta) provides 30%-50% of the calories consumed in Sub-Saharan Africa and is widely used in South America. γ-ray analysis was used to measure activity concentrations of 238 U, 232 Th, and 40 K in cassava root and soil. The TF values for 238 U, 232 Th, and 40 K were in the range 0.06-0.12, 0.01-0.10 and 0.04-0.28 respectively. The median transfer factors were 0.10 ( 238 U), 0.04 ( 232 Th) and 0.08 ( 40 K). For 238 U and 232 Th, the highest TF values were 0.12 and 0.10 respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of salicylic acid pretreatment on seeds germination and some defence mechanisms of Zea mays plants under copper stress.

PubMed

Moravcová, Šárka; Tůma, Jiří; Dučaiová, Zuzana Kovalíková; Waligórski, Piotr; Kula, Monika; Saja, Diana; Słomka, Aneta; Bąba, Wojciech; Libik-Konieczny, Marta

2018-01-01

The study was focused on the influence of salicylic acid (SA) on maize seeds germination and on some physiological and biochemical processes in maize plants growing in the hydroponic culture under copper (Cu) stress. A significant influence of SA pretreatment on the advanced induction of the maize seeds metabolic activity and the level of the endogenous SA in germinated seeds and developing roots have been stated. Although, the ability of maize seeds to uptake SA and accumulate it in the germinated roots was confirmed, the growth inhibition of Cu-stressed maize seedlings was not ameliorated by SA seeds pretreatment. Cu-stressed plants exhibited a decrease in the photosynthetic pigment concentration and the increase in non-photochemical quenching (NPQ) - an indicator of an excess energy in PSII antenna assemblies lost as a heat. The amelioration effect of SA application was found only for carotenoids content which increased in stressed plants. It was also shown that maize roots growing in stress conditions significantly differed in the chemical composition in comparison to the roots of control plants, but the SA pretreatment did not affect these differences. On the other hand, it was found that SA seed pretreatment significantly influenced the ability of stressed plants to accumulate copper in the roots. It was stated that a higher level of exogenous SA application led to a lower accumulation of Cu ions in maize roots. Cu-stressed plants exhibited higher oxidative stress in roots than in leaves which was manifested as an increase in the concentration of hydrogen peroxide due to stress factor application. We observed an increase in catalase (CAT) activity in leaves of Cu-stressed plants which corresponded with a lower H 2 O 2 content when compared with roots where the hydrogen peroxide level was higher, and the inhibition of the CAT activity was found. Furthermore, we found that the SA seed pretreatment led to a decrease in the H 2 O 2 content in the roots of the Cu-stressed plants, but it did not influence the H 2 O 2 level in leaves. The increase in hydrogen peroxide content in the roots of Cu-stressed plants correlated with a higher activity of the MnSODI and MnSODII isoforms. It was found that SA pretreatment caused a decrease in MnSODII activity accompanied by the decrease in H 2 O 2 concentration. Achieved results indicated also that the changes in the chemical composition of the root tissue under copper stress constituted protection mechanisms of blocking copper flow into other plant organs. However, it might be assumed that the root tissue remodelling under Cu stress did not only prevent against the Cu ions uptake but also limited the absorption of minerals required for the normal growth leading to the inhibition of the plant development. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Ecophysiology of nickel phytoaccumulation: a simplified biophysical approach.

PubMed

Coinchelin, David; Bartoli, François; Robin, Christophe; Echevarria, Guillaume

2012-10-01

Solute active transport or exclusion by plants can be identified by the values of the Transpiration Stream Concentration Factor (TSCF=xylem:solution solute concentration ratio). The aim of this study was to estimate this parameter for Ni uptake by the Ni-hyperaccumulator Leptoplax emarginata or the Ni-excluder Triticum aestivum cultivar 'Fidel'. The Intact Plant TSCF for nickel (IPTSCF(Ni)) was calculated as the ratio between the nickel mass accumulation in the leaves and the nickel concentration in solution per volume of water transpired. Predominantly, Ni active transport occurred for L. emarginata, with IPTSCF(Ni) values of 4.7-7.2 and convective component proportions of the root Ni uptake flow of only 15-20% for a range of Ni concentrations in solutions of 2-16 µmol Ni l(-1), regardless of the growth period and the time of Ni uptake. Hyperaccumulator roots were permeable to both water and nickel (mean reflection coefficient for Ni, σ(Ni), of 0.06), which was mainly attributed to an absence of exodermis. Results provide a new view of the mechanisms of Ni hyperaccumulation. By contrast, the wheat excluder was characterized by an extremely low mean IPTSCF(Ni) value of 0.006, characterizing a predominantly Ni sequestration in roots. From a methodological viewpoint, the 'microscopic' TSCF(Ni), measured directly on excised plants was 2.4 times larger than its recommended 'macroscopic' IPTSCF(Ni) counterpart. Overall, IPTSCF and σ determined on intact transpiring plants appeared to be very useful biophysical parameters in the study of the mechanisms involved in metal uptake and accumulation by plants, and in their modelling.

Statistical Analysis Of Heavy Metals Concentration In Watermelon Plants Irrigated By Wastewater

NASA Astrophysics Data System (ADS)

Khanjani, M. J.; Maghsoudi moud, A. A.; Saffari, V. R.; Hashamipor, S. M.; Soltanizadeh, M.

2008-01-01

Concentration of heavy metals in vegetables irrigated by urban wastewater is a cause of serious concern due to the potentials health problems of consuming contaminated produce. In this study it is tried to model the concentration of heavy metals (Cd, Cr, Cu, Fe,…) as a function of their concentration in watermelon roots and stems. Our study shows there is a good relationship between them for most of collected data. By measuring the concentration in root and stem of watermelon plant samples before harvesting, the concentration of heavy metal in watermelon's fruit can be estimated by presented mathematical models. This study shows the concentrations of heavy metals in fruits, roots and stems of watermelon plants are very high and in dangerous level when irrigated by municipal waste water.

Physiological assessment and path coefficient analysis to improve evaluation of alfalfa autotoxicity.

PubMed

Chon, Sang-Uk; Nelson, C Jerry; Coutts, John H

2003-11-01

Reseeding of alfalfa is affected until autotoxic chemicals break down or are dispersed, often requiring a year or more. Bioassays of seed germination and early seedling growth, on agar medium in petri dishes, were conducted to evaluate autotoxic responses of 20 alfalfa germplasms to water-soluble extracts of alfalfa leaf tissue. Root length, 120 hr after placing imbibed seed on agar, was more sensitive to the autotoxin(s) than was hypocotyl length, germination speed, and final germination percentage. Path coefficient analyses showed variation in root length had 7-17 times more effect than variation in hypocotyl length in determining autotoxic effects on total seedling length. Although variations in seed size and germination rate were negatively associated (P < 0.05) with final root length, the autotoxin had little effect on these factors relative to that on root length. Germplasms in the control differed (P < 0.05) in root length, requiring tolerance to be evaluated as percent of control. Germplasms, as percent of control, differed significantly (P < 0.05) at extract concentrations of 1.0 and 4.0 g l(-1), but the range and LSD were more favorable for selection at 1.0 g l(-1). Root length is appropriate for genetic assessments of tolerance to the autotoxin when expressed as percent of control.

Effects of elevated CO2 on fine root biomass are reduced by aridity but enhanced by soil nitrogen: A global assessment.

PubMed

Piñeiro, Juan; Ochoa-Hueso, Raúl; Delgado-Baquerizo, Manuel; Dobrick, Silvan; Reich, Peter B; Pendall, Elise; Power, Sally A

2017-11-10

Plant roots play a crucial role in regulating key ecosystem processes such as carbon (C) sequestration and nutrient solubilisation. Elevated (e)CO 2 is expected to alter the biomass of fine, coarse and total roots to meet increased demand for other resources such as water and nitrogen (N), however, the magnitude and direction of observed changes vary considerably between ecosystems. Here, we assessed how climate and soil properties mediate root responses to eCO 2 by comparing 24 field-based CO 2 experiments across the globe including a wide range of ecosystem types. We calculated response ratios (i.e. effect size) and used structural equation modelling (SEM) to achieve a system-level understanding of how aridity, mean annual temperature and total soil nitrogen simultaneously drive the response of total, coarse and fine root biomass to eCO 2 . Models indicated that increasing aridity limits the positive response of fine and total root biomass to eCO 2 , and that fine (but not coarse or total) root responses to eCO 2 are positively related to soil total N. Our results provide evidence that consideration of factors such as aridity and soil N status is crucial for predicting plant and ecosystem-scale responses to future changes in atmospheric CO 2 concentrations, and thus feedbacks to climate change.

Root-zone temperature and nitrogen affect the yield and secondary metabolite concentration of fall- and spring-grown, high-density leaf lettuce.

PubMed

Bumgarner, Natalie R; Scheerens, Joseph C; Mullen, Robert W; Bennett, Mark A; Ling, Peter P; Kleinhenz, Matthew D

2012-01-15

Understanding the effects of temperature and nitrogen levels on key variables, particularly under field conditions during cool seasons of temperate climates, is important. Here, we document the impact of root-zone heating and nitrogen (N) fertility on the accumulation and composition of fall- and spring-grown lettuce biomass. A novel, scalable field system was employed. Direct-seeded plots containing a uniform, semi-solid, and nearly stable rooting medium were established outdoors in 2009 and 2010; each contained one of eight combinations of root-zone heating (-/+) and N fertility (0, 72, 144, and 576 mg day(-1)). Root-zone heating increased but withholding N decreased biomass accumulation in both years. Low N supplies were also associated with greater anthocyanin and total antioxidant power but lower N and phosphorus levels. Tissue chlorophyll a and vitamin C levels tracked root-zone temperature and N fertility more closely in 2009 and 2010, respectively. Experimentally imposed root-zone temperature and N levels influenced the amount and properties of fall- and spring-grown lettuce tissue. Ambient conditions, however, dictated which of these factors exerted the greatest effect on the variables measured. Collectively, the results point to the potential for gains in system sustainability and productivity, including with respect to supplying human nutritional units. Copyright © 2011 Society of Chemical Industry.

Three tropical seagrasses as potential bio-indicators to trace metals in Xincun Bay, Hainan Island, South China

NASA Astrophysics Data System (ADS)

Li, Lei; Huang, Xiaoping

2012-03-01

Concentrations of the trace metals Cu, Cd, Pb, and Zn were measured in seawater, rhizosphere sediments, interstitial water, and the tissues of three tropical species of seagrasses ( Thalassia hemprichii, Enhalus acoroides and Cymodocea rotundata) from Xincun Bay of Hainan Island, South China. We analyzed different environmental compartments and the highest concentrations of Pb and Zn were found in the interstitial and seawater. The concentrations of Cd and Zn were significantly higher in blades compared with roots or rhizomes in T. hemprichii and E. acoroides, respectively. A metal pollution index (MPI) demonstrated that sediment, interstitial water, and seagrasses in the sites located nearest anthropogenic sources of pollution had the most abundant metal concentrations. There was obvious seasonal variation of these metals in the three seagrasses with higher concentrations of Cu, Pb and Zn in January and Cd in July. Furthermore, the relationships between metal concentrations in seagrasses and environmental compartments were positively correlated significantly. The bioconcentration factors (BCF) demonstrated that Cd from the tissues of the three seagrasses might be absorbed from the sediment by the roots. However, for C. rotundata, Zn is likely to be derived from the seawater through its blades. Therefore, the blades of T. hemprichii, E. acoroides and C. rotundata are potential bio-indicators to Cd content in sediment, and additionally Zn content ( C. rotundata only) in seawater.

Competing factors of compost concentration and proximity to root affect the distribution of streptomycetes.

PubMed

Inbar, Ehud; Green, Stefan J; Hadar, Yitzhak; Minz, Dror

2005-07-01

Streptomycetes are important members of soil microbial communities and are particularly active in the degradation of recalcitrant macromolecules and have been implicated in biological control of plant disease. Using a streptomycetes-specific polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (PCR-DGGE) methodology coupled with band excision and sequence analysis, we examined the effect of grape marc compost amendment to soil on cucumber plant-associated streptomycetes community composition. We observed that both compost amendment and proximity to the root surface influenced the streptomycetes community composition. A strong root selection for a soil-derived Streptomycete, most closely related to Streptomyces thermotolerans, S. iakyrus, and S. thermocarboxydus, was independent of compost amendment rate. However, while the impact of compost amendment was mitigated with increasing proximity to the root, high levels of compost amendment resulted in the detection of compost-derived species on the root surface. Conversely, in rhizosphere and non-rhizosphere soils, the community composition of streptomycetes was affected strongly even by modest compost amendment. The application of a streptomycetes-specific PCR primer set combined with DGGE analysis provided a rapid means of examining the distribution and ecology of streptomycetes in soils and plant-associated environments.

Rhizofiltration - the use of plants to remove heavy metals from aqueous streams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raskin, I.; Dushenkov, V.; Kumar, P.B.A.N.

1995-12-31

Heavy metal pollution of water is a major environmental problem facing the modern world. Rhizofiltration - the use of plant roots to remove heavy metals from water is an emerging environmental clean-up technology. Roots of many hydroponically grown terrestrial plants e.g. Indian mustard, sunflower (Hefianthus annuus L.) and various grasses effectively removed toxic metals such as CU{sup -2}, Cd{sup +2}Cr{sup +6}, Ni{sup +2}Pb{sup +2} and Zn{sup +2} from aqueous solutions. Roots of B. juncea concentrated these metals 131 to 563-fold (on a DW basis) above initial solution concentrations. Pb removal was based on tissue absorption and on root-mediated Pb precipitationmore » in the form of insoluble inorganic compounds, mainly Pb phosphate. At high Pb concentrations precipitation played a progressively more important role in Pb removal than tissue absorption, which saturated at approximately 100 {mu}g Pb/g DW root. Dried roots were much less effective than live roots in accumulating Pb and in removing Pb from the solution.« less

CuO Nanoparticles Inhibited Root Growth from Brassica nigra Seedlings but Induced Root from Stem and Leaf Explants.

PubMed

Zafar, Hira; Ali, Attarad; Zia, Muhammad

2017-01-01

Interests associated with nanoparticles (NPs) are budding due to their toxicity to living species. The lethal effect of NPs depends on their nature, size, shape, and concentration. Present investigation reports that CuO NPs badly affected Brassica nigra seed germination and seedling growth parameters. However, variation in antioxidative activities and nonenzymatic oxidants is observed in plantlets. Culturing the leaf and stem explants on MS medium in presence of low concentration of CuO NPs (1-20 mg l -1 ) produces white thin roots with thick root hairs. These roots also show an increase in DPPH radical scavenging activity (up to 80 % at 10 mg l -1 ), total antioxidant, and reducing power potential (maximum in presence of 10 mg l -1 CuO NPs in the media). Nonenzymatic antioxidative molecules, phenolics and flavonoids, are observed elevated but NPs concentration dependent. We can conclude that CuO NPs can induce rooting from plant explants cultured on appropriate medium. These roots can be explored for the production of active chemical constituents.

Long-distance abscisic acid signalling under different vertical soil moisture gradients depends on bulk root water potential and average soil water content in the root zone.

PubMed

Puértolas, Jaime; Alcobendas, Rosalía; Alarcón, Juan J; Dodd, Ian C

2013-08-01

To determine how root-to-shoot abscisic acid (ABA) signalling is regulated by vertical soil moisture gradients, root ABA concentration ([ABA](root)), the fraction of root water uptake from, and root water potential of different parts of the root zone, along with bulk root water potential, were measured to test various predictive models of root xylem ABA concentration [RX-ABA](sap). Beans (Phaseolus vulgaris L. cv. Nassau) were grown in soil columns and received different irrigation treatments (top and basal watering, and withholding water for varying lengths of time) to induce different vertical soil moisture gradients. Root water uptake was measured at four positions within the column by continuously recording volumetric soil water content (θv). Average θv was inversely related to bulk root water potential (Ψ(root)). In turn, Ψ(root) was correlated with both average [ABA](root) and [RX-ABA](sap). Despite large gradients in θv, [ABA](root) and root water potential was homogenous within the root zone. Consequently, unlike some split-root studies, root water uptake fraction from layers with different soil moisture did not influence xylem sap (ABA). This suggests two different patterns of ABA signalling, depending on how soil moisture heterogeneity is distributed within the root zone, which might have implications for implementing water-saving irrigation techniques. © 2013 John Wiley & Sons Ltd.

Adsorption and inhibition of CuO nanoparticles on Arabidopsis thaliana root

NASA Astrophysics Data System (ADS)

Xu, Lina

2018-02-01

CuO NPs, the size ranging from 20 to 80 nm were used to detect the adsorption and inhibition on the Arabidopsis thaliana roots. In this study, CuO NPs were adsorbed and agglomerated on the surface of root top after exposed for 7 days. With the increasing of CuO NPs concentrations, CuO NPs also adsorbed on the meristernatic zone. The growth of Arabidopsis thaliana lateral roots were also inhibited by CuO NPs exposure. The Inhibition were concentration dependent. The number of root top were 246, 188 and 123 per Arabidopsis thaliana, respectively. The number of root tops after CuO NPs exposure were significantly decreased compared with control groups. This results suggested the phytotoxicity of CuO NPs on Arabidopsis thaliana roots.

[Allelopathic effects of cultured Cucurbita moschata root exudates].

PubMed

Li, Min; Ma, Yongqin; Shui, Junfeng

2005-04-01

By using the techniques of tissue culture, bio-assay and laboratory analysis, this paper studied the effects of the allelopathic chemicals from pumpkin (Cucurbita moschata) roots on the seed germination and seedling growth of pumpkin, wheat (Triticum aestivum), and radish (Raphanus sativus). The pumpkin root was cultured on a sterile B5 media, and the concentrations of macro- and microelements, organic supplements and hormones in the media were adjusted by using an orthogonal design. After culturing, the culture media was filtered and used in a bioassay to test the autotoxicity and allelopathic effects. The results showed that the pumpkin had both autotoxic and allelopathic effects, and the media having been used to culture the pumpkin roots contained the chemicals that significantly inhibited the seedling growth of wheat and radish. The allelopathic effect decreased when the culture media was diluted. The production of allelochemicals seemed to be related to the growth rate of the pumpkin roots. When the root growth was rapid, the concentration of allelochemicals was high. The allelopathic effect was stronger on radish than on wheat. The optimum concentrations of macro- and microelements, vitamins and hormones for culturing pumpkin root were determined, and the effect of pumpkin root nutrition on the production of allelochemicals was tested. The results indicated that pumpkin root nutrition had a significant effect on the production of allelochemicals.

Experimentally reduced root–microbe interactions reveal limited plasticity in functional root traits in Acer and Quercus

PubMed Central

Lee, Mei-Ho; Comas, Louise H.; Callahan, Hilary S.

2014-01-01

Background and Aims Interactions between roots and soil microbes are critical components of below-ground ecology. It is essential to quantify the magnitude of root trait variation both among and within species, including variation due to plasticity. In addition to contextualizing the magnitude of plasticity relative to differences between species, studies of plasticity can ascertain if plasticity is predictable and whether an environmental factor elicits changes in traits that are functionally advantageous. Methods To compare functional traits and trait plasticities in fine root tissues with natural and reduced levels of colonization by microbial symbionts, trimmed and surface-sterilized root segments of 2-year-old Acer rubrum and Quercus rubra seedlings were manipulated. Segments were then replanted into satellite pots filled with control or heat-treated soil, both originally derived from a natural forest. Mycorrhizal colonization was near zero in roots grown in heat-treated soil; roots grown in control soil matched the higher colonization levels observed in unmanipulated root samples collected from field locations. Key Results Between-treatment comparisons revealed negligible plasticity for root diameter, branching intensity and nitrogen concentration across both species. Roots from treated soils had decreased tissue density (approx. 10–20 %) and increased specific root length (approx. 10–30 %). In contrast, species differences were significant and greater than treatment effects in traits other than tissue density. Interspecific trait differences were also significant in field samples, which generally resembled greenhouse samples. Conclusions The combination of experimental and field approaches was useful for contextualizing trait plasticity in comparison with inter- and intra-specific trait variation. Findings that root traits are largely species dependent, with the exception of root tissue density, are discussed in the context of current literature on root trait variation, interactions with symbionts and recent progress in standardization of methods for quantifying root traits. PMID:24363335

External apical root resorption in maxillary incisors in orthodontic patients: associated factors and radiographic evaluation

PubMed Central

Patanaporn, Virush; Janhom, Apirum; Korwanich, Narumanus

2012-01-01

Purpose This study was performed to evaluate the incidence and degree of external apical root resorption of maxillary incisors after orthodontic treatment and to evaluate particular associated factors related to external apical root resorption. Materials and Methods The records and maxillary incisor periapical radiographs of 181 patients were investigated. Crown and root lengths were measured and compared on the pre- and post-treatment periapical radiographs. Crown length was measured from the center of the incisal edge to the midpoint of the cemento-enamel junction (CEJ). Root length was measured from the CEJ midpoint to the root apex. A correction factor for the enlargement difference was used to calculate root resorption. Results The periapical radiographs of 564 teeth showed that the average root resorption was 1.39±1.27 (8.24±7.22%) and 1.69±1.14 mm (10.16±6.78%) for the maxillary central and lateral incisors, respectively. The results showed that the dilacerated or pointed roots, maxillary premolar extraction cases, and treatment duration were highly significant factors for root resorption (p<0.001). Allergic condition was a significant factor at p<0.01. Age at the start of treatment, large overjet, and history of facial trauma were also factors significantly associated with root resorption (p<0.05). There was no statistically significant difference in root resorption among the factors of gender, overbite, tongue-thrusting habit, types of malocclusion, and types of bracket. Conclusion These results suggested that orthodontic treatment should be carefully performed in pre-treatment extraction patients who have pointed or dilacerated roots and need long treatment duration. PMID:23071964

Chemistry and long-term decomposition of roots of Douglas-fir grown under elevated atmospheric carbon dioxide and warming conditions.

PubMed

Chen, H; Rygiewicz, P T; Johnson, M G; Harmon, M E; Tian, H; Tang, J W

2008-01-01

Elevated atmospheric CO(2) concentrations and warming may affect the quality of litters of forest plants and their subsequent decomposition in ecosystems, thereby potentially affecting the global carbon cycle. However, few data on root tissues are available to test this feedback to the atmosphere. In this study, we used fine (diameter < or = 2 mm) and small (2-10 mm) roots of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings that were grown for 4 yr in a 2 x 2 factorial experiment: ambient or elevated (+ 180 ppm) atmospheric CO(2) concentrations, and ambient or elevated (+3.8 degrees C) atmospheric temperature. Exposure to elevated CO(2) significantly increased water-soluble extractives concentration (%WSE), but had little effect on the concentration of N, cellulose, and lignin of roots. Elevated temperature had no effect on substrate quality except for increasing %WSE and decreasing the %lignin content of fine roots. No significant interaction was found between CO(2) and temperature treatments on substrate quality, except for %WSE of the fine roots. Short-term (< or = 9 mo) root decomposition in the field indicated that the roots from the ambient CO(2) and ambient temperature treatment had the slowest rate. However, over a longer period of incubation (9-36 mo) the influence of initial substrate quality on root decomposition diminished. Instead, the location of the field incubation sites exhibited significant control on decomposition. Roots at the warmer, low elevation site decomposed significantly faster than the ones at the cooler, high elevation site. This study indicates that short-term decomposition and long-term responses are not similar. It also suggests that increasing atmospheric CO(2) had little effect on the carbon storage of Douglas-fir old-growth forests of the Pacific Northwest.

Effects of IBA and NAA treatments on rooting Douglas-fir stem cuttings.

Treesearch

D.L. Copes

2000-01-01

The effectiveness of six IBA and four NAA concentrations, four combinations of IBA and NAA concentrations, and control were tested for their ability to enhance rooting frequency (%) of Douglas-fir cuttings. Two IBA and one NAA treatments were also compared to the control for quality of root system. Between 1984 and 1998, six independent studies were conducted in mist...

In what root-zone N concentration does nitrate start to leach significantly? A reasonable answer from modeling Mediterranean field data and closed root-zone experiments

NASA Astrophysics Data System (ADS)

Kurtzman, D.; Kanner, B.; Levy, Y.; Shapira, R. H.; Bar-Tal, A.

2017-12-01

Closed-root-zone experiments (e.g. pots, lyzimeters) reveal in many cases a mineral-nitrogen (N) concentration from which the root-N-uptake efficiency reduces significantly and nitrate leaching below the root-zone increases dramatically. A les-direct way to reveal this threshold concentration in agricultural fields is to calibrate N-transport models of the unsaturated zone to nitrate data of the deep samples (under the root-zone) by fitting the threshold concentration of the nitrate-uptake function. Independent research efforts of these two types in light soils where nitrate problems in underlying aquifers are common reviled: 1) that the threshold exists for most crops (filed, vegetables and orchards); 2) nice agreement on the threshold value between the two very different research methodologies; and 3) the threshold lies within 20-50 mg-N/L. Focusing on being below the threshold is a relatively simple aim in the way to maintain intensive agriculture with limited effects on the nitrate concentration in the underlying water resource. Our experience show that in some crops this threshold coincides with the end-of-rise of the N-yield curve (e.g. corn); in this case, it is relatively easy to convince farmers to fertilize below threshold. In other crops, although significant N is lost to leaching the crop can still use higher N concentration to increase yield (e.g. potato).

Effect of utilization of tomato extract and foliar fertilizer as media on shoots multiplication of banana cv Ambon in vitro

NASA Astrophysics Data System (ADS)

Bidhari, L. A.; Purwanto, E.; Yunus, A.

2018-03-01

The good quality banana seeds are still difficult to obtain. There are two ways to provide seeds, namely conventional and tissue culture (in vitro). Tomato extract contains natural ZPT or phytohormone which can be utilized in modification of banana tissue culture media. The aim of this study was to determine the influence of media types and tomato extracts in various concentrations for multiplication of banana cv. Ambon in vitro. The study was conducted from October - December 2016 at the Tissue Culture Laboratory of Horticulture Seed Center, Salaman, Magelang. The experimental design used was completely randomized design with two treatment factors. The firs factor was media type with the addition of foliar fertilizer, the second factor was modification of tomato extract with 4 levels. The results showed that the different of the treated media treatment did not affect the emerge of leaf and leaf length, the number of roots and root length. The emerge of the leaves of all treatments occurred at 6 days after planting with the highest average length was obtained in MS treatment with a combination of tomato extract 50 ml/l (10.3 cm). The use of MS medium with a combination of tomato extract 50 ml/l generated the average root number 15.5 with a root lengths 7.5 cm. Substitution of MS medium with tomato extract and foliar fertilizer did not show better results compared to the use of MS media in the multiplication of banana shoots in tissue culture.

Visualization of highly dynamic F-actin plus ends in growing phaseolus vulgaris root hair cells and their responses to Rhizobium etli nod factors.

PubMed

Zepeda, Isaac; Sánchez-López, Rosana; Kunkel, Joseph G; Bañuelos, Luis A; Hernández-Barrera, Alejandra; Sánchez, Federico; Quinto, Carmen; Cárdenas, Luis

2014-03-01

Legume plants secrete signaling molecules called flavonoids into the rhizosphere. These molecules activate the transcription of rhizobial nod genes, which encode proteins involved in the synthesis of signaling compounds named Nod factors (NFs). NFs, in turn, trigger changes in plant gene expression, cortical cell dedifferentiation and mitosis, depolarization of the root hair cell membrane potential and rearrangement of the actin cytoskeleton. Actin polymerization plays an important role in apical growth in hyphae and pollen tubes. Using sublethal concentrations of fluorescently labeled cytochalasin D (Cyt-Fl), we visualized the distribution of filamentous actin (F-actin) plus ends in living Phaseolus vulgaris and Arabidopsis root hairs during apical growth. We demonstrated that Cyt-Fl specifically labeled the newly available plus ends of actin microfilaments, which probably represent sites of polymerization. The addition of unlabeled competing cytochalasin reduced the signal, suggesting that the labeled and unlabeled forms of the drug bind to the same site on F-actin. Exposure to Rhizobium etli NFs resulted in a rapid increase in the number of F-actin plus ends in P. vulgaris root hairs and in the re-localization of F-actin plus ends to infection thread initiation sites. These data suggest that NFs promote the formation of F-actin plus ends, which results in actin cytoskeleton rearrangements that facilitate infection thread formation.

A preliminary analysis of the effects of bisphenol A on the plant root growth via changes in endogenous plant hormones.

PubMed

Li, Xingyi; Wang, Lihong; Wang, Shengman; Yang, Qing; Zhou, Qing; Huang, Xiaohua

2018-04-15

Bisphenol A (BPA) is ubiquitous in the environment worldwide, affecting plant growth and development. Endogenous plant hormones serve as switches that regulate plant growth and development. However, plants have different physiological requirements and environmental adaptive capacities during the different growth stages. Here, we investigated the effects of BPA on soybean (Glycine max L.) root growth at the three growth stages and analyzed the mechanisms underlying the effects of BPA on the root growth by assessing changes in endogenous hormone. The results showed that low concentration of BPA (1.5mgL -1 ) improved root growth (except at the seed-filling stage), increased indole-3-acetic acid (IAA) content at the first two growth stages, and increased zeatin (ZT) content and decreased gibberellic acid (GA 3 ) content at the seedling stage. But low concentration of BPA caused decreased ethylene (ETH) contents and constant abscisic acid (ABA) content at all three stages. However, BPA at moderate and high concentrations (6.0 and 12.0mgL -1 ) inhibited root growth, causing the decreased IAA, GA 3 and ETH contents and increased ABA content at all three growth stages. The change degrees of above indices were weakened with prolonging the growth stages. After BPA withdrawal, both the root growth and the hormone contents recovered (with the exception of ZT and ETH), and the recovery degrees had negative correlation with the BPA exposure concentration and had positive correlation with the growth stage. Changes in residual BPA content in the roots were also observed at different BPA concentrations and different growth stages. Our results demonstrated the effects of BPA on root growth were related to BPA-induced changes in hormone, which performed differently at various growth stages. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of Naphthalene Acetic Acid on Adventitious Root Development and Associated Physiological Changes in Stem Cutting of Hemarthria compressa

PubMed Central

Zhang, Xin-Quan; Yang, Wen-Yu; Wan, Yan; Ma, Ying-Mei; Zhu, Yong-Qun; Peng, Yan; Huang, Lin-Kai

2014-01-01

In order to find a way to induce rooting on cuttings of Hemarthria compressa cv. Ya’an under controlled conditions, a project was carried out to study the effect of naphthalene acetic acid (NAA) on rooting in stem cuttings and related physiological changes during the rooting process of Hemarthria compressa. The cuttings were treated with five concentrations of NAA (0, 100, 200 300, 400 mg/l) at three soaking durations (10, 20, 30 minutes), and cuttings without treatment were considered as control. Samples were planted immediately into pots after treatment. IAA-oxidase (IAAO) activity, peroxidase (POD) activity and polyphenol oxidase (PPO) activity were determined after planting. Results showed that NAA had positive effect on rooting at the concentration of 200 mg/l compared to other concentrations at 30 days after planting (DAP). Among the three soaking durations, 20 minutes (min) of 200 mg/l NAA resulted in higher percentages of rooting, larger numbers of adventitious roots and heavier root dry weight per cutting. The lowest IAAO activity was obtained when soaked at 200 mg/l NAA for 20 min soaking duration. This was consistent with the best rooting ability, indicating that the lower IAAO activity, the higher POD activity and PPO activity could be used as an indicator of better rooting ability for whip grass cuttings and might serve as a good marker for rooting ability in cuttings. PMID:24595064

User’s guide to the collection and analysis of tree cores to assess the distribution of subsurface volatile organic compounds

USGS Publications Warehouse

Vroblesky, Don A.

2008-01-01

Analysis of the volatile organic compound content of tree cores is an inexpensive, rapid, simple approach to examining the distribution of subsurface volatile organic compound contaminants. The method has been shown to detect several volatile petroleum hydrocarbons and chlorinated aliphatic compounds associated with vapor intrusion and ground-water contamination. Tree cores, which are approximately 3 inches long, are obtained by using an increment borer. The cores are placed in vials and sealed. After a period of equilibration, the cores can be analyzed by headspace analysis gas chromatography. Because the roots are exposed to volatile organic compound contamination in the unsaturated zone or shallow ground water, the volatile organic compound concentrations in the tree cores are an indication of the presence of subsurface volatile organic compound contamination. Thus, tree coring can be used to detect and map subsurface volatile organic compound contamination. For comparison of tree-core data at a particular site, it is important to maintain consistent methods for all aspects of tree-core collection, handling, and analysis. Factors affecting the volatile organic compound concentrations in tree cores include the type of volatile organic compound, the tree species, the rooting depth, ground-water chemistry, the depth to the contaminated horizon, concentration differences around the trunk related to variations in the distribution of subsurface volatile organic compounds, concentration differences with depth of coring related to volatilization loss through the bark and possibly other unknown factors, dilution by rain, seasonal influences, sorption, vapor-exchange rates, and within-tree volatile organic compound degradation.

Effects of different sewage sludge applications on heavy metal accumulation, growth and yield of spinach (Spinacia oleracea L.).

PubMed

Eid, Ebrahem M; El-Bebany, Ahmed F; Alrumman, Sulaiman A; Hesham, Abd El-Latif; Taher, Mostafa A; Fawy, Khaled F

2017-04-03

In this study, we present the response of spinach to different amendment rates of sewage sludge (0, 10, 20, 30, 40 and 50 g kg -1 ) in a greenhouse pot experiment, where plant growth, biomass and heavy metal uptake were measured. The results showed that sewage sludge application increased soil electric conductivity (EC), organic matter, chromium and zinc concentrations and decreased soil pH. All heavy metal concentrations of the sewage sludge were below the permissible limits for land application of sewage sludge recommended by the Council of the European Communities. Biomass and all growth parameters (except the shoot/root ratio) of spinach showed a positive response to sewage sludge applications up to 40 g kg -1 compared to the control soil. Increasing the sewage sludge amendment rate caused an increase in all heavy metal concentrations (except lead) in spinach root and shoot. However, all heavy metal concentrations (except chromium and iron) were in the normal range and did not reach the phytotoxic levels. The spinach was characterized by a bioaccumulation factor <1.0 for all heavy metals. The translocation factor (TF) varied among the heavy metals as well as among the sewage sludge amendment rates. Spinach translocation mechanisms clearly restricted heavy metal transport to the edible parts (shoot) because the TFs for all heavy metals (except zinc) were <1.0. In conclusion, sewage sludge used in the present study can be considered for use as a fertilizer in spinach production systems in Saudi Arabia, and the results can serve as a management method for sewage sludge.

Iron isotope fingerprints of redox and biogeochemical cycling in the soil-water-rice plant system of a paddy field.

PubMed

Garnier, J; Garnier, J-M; Vieira, C L; Akerman, A; Chmeleff, J; Ruiz, R I; Poitrasson, F

2017-01-01

The iron isotope composition was used to investigate dissimilatory iron reduction (DIR) processes in an iron-rich waterlogged paddy soil, the iron uptake strategies of plants and its translocation in the different parts of the rice plant along its growth. Fe concentration and isotope composition (δ 56 Fe) in irrigation water, precipitates from irrigation water, soil, pore water solution at different depths under the surface water, iron plaque on rice roots, rice roots, stems, leaves and grains were measured. Over the 8.5-10cm of the vertical profiles investigated, the iron pore water concentration (0.01 to 24.3mg·l -1 ) and δ 56 Fe (-0.80 to -3.40‰) varied over a large range. The significant linear co-variation between Ln[Fe] and δ 56 Fe suggests an apparent Rayleigh-type behavior of the DIR processes. An average net fractionation factor between the pore water and the soil substrate of Δ 56 Fe≈-1.15‰ was obtained, taking the average of all the δ 56 Fe values weighted by the amount of Fe for each sample. These results provide a robust field study confirmation of the conceptual model of Crosby et al. (2005, 2007) for interpreting the iron isotope fractionation observed during DIR, established from a series of laboratories experiments. In addition, the strong enrichment of heavy Fe isotope measured in the root relative to the soil solution suggest that the iron uptake by roots is more likely supplied by iron from plaque and not from the plant-available iron in the pore water. Opposite to what was previously observed for plants following strategy II for iron uptake from soils, an iron isotope fractionation factor of -0.9‰ was found from the roots to the rice grains, pointing to isotope fractionation during rice plant growth. All these features highlight the insights iron isotope composition provides into the biogeochemical Fe cycling in the soil-water-rice plant systems studied in nature. Copyright © 2016 Elsevier B.V. All rights reserved.

Metal/metalloid content in plant parts and soils of Corylus spp. influenced by mining-metallurgical production of copper.

PubMed

Radojevic, Ana A; Serbula, Snezana M; Kalinovic, Tanja S; Kalinovic, Jelena V; Steharnik, Mirjana M; Petrovic, Jelena V; Milosavljevic, Jelena S

2017-04-01

The town of Bor and its surroundings (Serbia) have been under environmental pollution for more than a century, due to exploitation of large copper deposits. Naturally present Corylus spp. were sampled in the surroundings of the mine and flotation tailings at 12 sites distributed in six zones with different pollution loads, under the assumption that all the zones were endangered except for the background. As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb and Zn inputs from soil and the air were evaluated in plant parts, in terms of absorption, accumulation and indication abilities of Corylus spp. The obtained results showed that As and Cu were the most enriched elements in soil, and their concentration exceeded the limit and remediation values proposed by the regulation. Plant parts (root, branch, leaf and catkin) also showed enrichment of most studied elements in wide ranges. According to the enrichment factor for plant, metal/metalloid inputs, particularly in leaves, were from anthropogenic origin. Plant absorption which occurred at the soil-root interface was low, based on the bioaccumulation factor, which could be indicative of resistance mechanisms of root to abiotic stress induced by a high content of elements in soil substrate. The values of bioaccumulation coefficient suggested weak and intermediate absorption and exclusion abilities of Corylus spp. to the studied elements. Element concentrations differ in unwashed and washed leaves, as well as pollution loads in plant and soil samples from the background, traffic and the sites with clear mining-metallurgical influence. Therefore, Corylus spp. could be promising in biomonitoring studies.

Cs phytoremediation by Sorghum bicolor cultivated in soil and in hydroponic system.

PubMed

Wang, Xu; Chen, Can; Wang, Jianlong

2017-04-03

Cs accumulation characteristics by Sorghum bicolor were investigated in hydroponic system (Cs level at 50-1000 μmol/L) and in soil (Cs-spiked concentration was 100 and 400 mg/kg soil). Two varieties of S. bicolor Cowly and Nengsi 2# grown on pot soil during the entire growth period (100 days) did not show significant differences on the height, dry weight (DW), and Cs accumulation. S. bicolor showed the potential phytoextraction ability for Cs-contaminated soil with the bioaccumulation factor (BCF) and the translocation factor (TF) values usually higher than 1 in soil system and in hydroponic system. The aerial parts of S. bicolor contributed to 86-92% of the total removed amounts of Cs from soil. Cs level in solution at 100 μmol/L gave the highest BCF and TF values of S. bicolor. Cs at low level tended to transfer to the aerial parts, whereas Cs at high level decreased the transfer ratio from root to shoot. In soil, the plant grew well when Cs spiked level was 100 mg/kg soil, but was inhibited by Cs at 400 mg/kg soil with Cs content in sorghum reaching 1147 mg/kg (roots), 2473 mg/kg (stems), and 2939 mg/kg (leaves). In hydroponic system, average Cs level in sorghum reached 5270 mg/kg (roots) and 4513 mg/kg (aerial parts), without significant damages to its biomass at 30 days after starting Cs treatment. Cs accumulation in sorghum tissues was positively correlated with the metal concentration in medium.

Automated Root Tracking with "Root System Analyzer"

NASA Astrophysics Data System (ADS)

Schnepf, Andrea; Jin, Meina; Ockert, Charlotte; Bol, Roland; Leitner, Daniel

2015-04-01

Crucial factors for plant development are water and nutrient availability in soils. Thus, root architecture is a main aspect of plant productivity and needs to be accurately considered when describing root processes. Images of root architecture contain a huge amount of information, and image analysis helps to recover parameters describing certain root architectural and morphological traits. The majority of imaging systems for root systems are designed for two-dimensional images, such as RootReader2, GiA Roots, SmartRoot, EZ-Rhizo, and Growscreen, but most of them are semi-automated and involve mouse-clicks in each root by the user. "Root System Analyzer" is a new, fully automated approach for recovering root architectural parameters from two-dimensional images of root systems. Individual roots can still be corrected manually in a user interface if required. The algorithm starts with a sequence of segmented two-dimensional images showing the dynamic development of a root system. For each image, morphological operators are used for skeletonization. Based on this, a graph representation of the root system is created. A dynamic root architecture model helps to determine which edges of the graph belong to an individual root. The algorithm elongates each root at the root tip and simulates growth confined within the already existing graph representation. The increment of root elongation is calculated assuming constant growth. For each root, the algorithm finds all possible paths and elongates the root in the direction of the optimal path. In this way, each edge of the graph is assigned to one or more coherent roots. Image sequences of root systems are handled in such a way that the previous image is used as a starting point for the current image. The algorithm is implemented in a set of Matlab m-files. Output of Root System Analyzer is a data structure that includes for each root an identification number, the branching order, the time of emergence, the parent identification number, the distance between branching point to the parent root base, the root length, the root radius and the nodes that belong to each individual root path. This information is relevant for the analysis of dynamic root system development as well as the parameterisation of root architecture models. Here, we show results of Root System Analyzer applied to analyse the root systems of wheat plants grown in rhizotrons. Different treatments with respect to soil moisture and apatite concentrations were used to test the effects of those conditions on root system development. Photographs of the root systems were taken at high spatial and temporal resolution and root systems are automatically tracked.

Decomposition and nutrient release from fresh and dried pine roots under two fertilizer regimes

Treesearch

Kim H. Ludovici; Lance W. Kress

2006-01-01

Root decomposition and nutrient release are typically estimated from dried root tissues; however, it is unlikely that roots dehydrate prior to decomposing. Soil fertility and root diameter may also affect the rate of decomposition. This study monitored mass loss and nutrient concentrations of dried and fresh roots of two size classes (

The key players of the primary root growth and development also function in lateral roots in Arabidopsis.

PubMed

Tian, Huiyu; Jia, Yuebin; Niu, Tiantian; Yu, Qianqian; Ding, Zhaojun

2014-05-01

The core regulators which are required for primary root growth and development also function in lateral root development or lateral root stem cell niche maintenance. The primary root systems and the lateral root systems are the two important root systems which are vital to the survival of plants. Though the molecular mechanism of the growth and development of both the primary root systems and the lateral root systems have been extensively studied individually in Arabidopsis, there are not so much evidence to show that if both root systems share common regulatory mechanisms. AP2 family transcription factors such as PLT1 (PLETHORA1) and PLT2, GRAS family transcription factors such as SCR (SCARECROW) and SHR (SHORT ROOT) and WUSCHEL-RELATED HOMEOBOX transcription factor WOX5 have been extensively studied and found to be essential for primary root growth and development. In this study, through the expression pattern analysis and mutant examinations, we found that these core regulators also function in lateral root development or lateral root stem cell niche maintenance.

[Allelopathy autotoxicity effects of aquatic extracts from rhizospheric soil on rooting and growth of stem cuttings in Pogostemon cablin].

PubMed

Tang, Kun; Li, Ming; Dong, Shan; Li, Yun-qi; Huang, Jie-wen; Li, Long-ming

2014-06-01

To study the allelopathy effects of aquatic extracts from rhizospheric soil on the rooting and growth of stem cutting in Pogostemon cablin, and to reveal its mechanism initially. The changes of rhizogenesis characteristics and physic-biochemical during cutting seedlings were observed when using different concentration of aquatic extracts from rhizospheric soil. Aquatic extracts from rhizospheric soil had significant inhibitory effects on rooting rate, root number, root length, root activity, growth rate of cutting with increasing concentrations of tissue extracts; The chlorophyll content of cutting seedlings were decreased, but content of MDA were increased, and activities of POD, PPO and IAAO in cutting seedlings were affected. Aquatic extracts from rhizospheric soil of Pogostemon cablin have varying degrees of inhibitory effects on the normal rooting and growth of stem cuttings.

Reduction of copper phytotoxicity by liming: A study of the root anatomy of young vines (Vitis labrusca L.).

PubMed

Ambrosini, Vítor Gabriel; Rosa, Daniel José; Corredor Prado, Jenny Paola; Borghezan, Marcelo; Bastos de Melo, George Wellington; Fonsêca de Sousa Soares, Cláudio Roberto; Comin, Jucinei José; Simão, Daniela Guimarães; Brunetto, Gustavo

2015-11-01

Frequent applications of copper (Cu)-based fungicides on vines causes the accumulation of this metal in vineyard soils, which can cause toxicity in young vines. However, liming may reduce these toxic effects. The present study aimed to evaluate the effects of Cu toxicity on the root anatomy of young vines and the alleviation of Cu toxicity by lime applications to contaminated sandy soil. The treatments consisted of the addition of lime (0.0, 1.5 and 3.0 Mg ha(-1)) and two Cu concentrations (0 and 50 mg kg(-1)) to Typic Hapludalf soil. Young vines 'Niágara Branca' (Vitis labrusca L.) were obtained by micropropagation and cultivated for 70 days. The young vines grown with Cu and without liming presented a disorganized root structure; reduced root cap size; increased diameter (47%), cortex area (128%), vascular cylinder area (93%), and number of cortical layers and cells containing phenolic compounds (132%); and reduced root (41%), stem (44%) and leaf dry mass (21%) and height increase (55%). Moreover, Cu exposure reduced Ca concentrations (13%) and increased Cu concentrations (371%) in the roots. Liming, primarily with the highest tested dose, increased the soil pH (from 4.4 to 5.4-6.1), decreased the Cu concentration in the soil (extracted by CaCl2), increased the calcium (Ca) and magnesium (Mg) uptake by plants, prevented root anatomical changes and benefited young vine growth in soil with higher Cu concentrations. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Effective Use of Marine Algal Products in the Management of Plant-Parasitic Nematodes

PubMed Central

Paracer, Surindar; Tarjan, Armen C.; Hodgson, Lynn M.

1987-01-01

Algal extracts were ineffective against Meloidogyne spp., Panagrellus redivivus, and Neoaplectana carpocapsae at 1.0% aqueous concentrations, with the exception of Spatoglossum schroederi. S. schroederi killed Meloidogyne incognita, M. javanica, M. acrita, and Hoplolaimus galeatus at concentrations of 1.0, 0.75, and 0.50%. Extracts from S. schroederi at a concentration of 1.0% were ineffective against Hirschmanniella caudacrena and Belonolaimus longicaudatus. Spatoglossum schroederi, Botryocladia occidentalis, and Bryothamnion triquestrum when used as soil amendments at 0.5-1.0% concentrations (by weight) produced significant reduction of root gall development in tomato plants infected with M. incognita. Tomato plant growth was significantly improved by these algae, as well as by Caulerpa prolifera. Soil amendments of S. schroederi at concentrations of 0.5 and 1.0% significantly reduced root galling of tomato infected with M. incognita, M. arenaria, and M. javanica. Tomatoes grown in algal-soil mixture produced significantly heavier shoots and roots than plants raised in autoclaved soil. No significant differences in root-knot indices, nor in fresh and dry weights of tomato, were noted between the two concentrations of algal-soil mixture. PMID:19290129

Response to non-uniform salinity in the root zone of the halophyte Atriplex nummularia: growth, photosynthesis, water relations and tissue ion concentrations

PubMed Central

Bazihizina, Nadia; Colmer, Timothy D.; Barrett-Lennard, Edward G.

2009-01-01

Background and Aims Soil salinity is often heterogeneous, yet the physiology of halophytes has typically been studied with uniform salinity treatments. An evaluation was made of the growth, net photosynthesis, water use, water relations and tissue ions in the halophytic shrub Atriplex nummularia in response to non-uniform NaCl concentrations in a split-root system. Methods Atriplex nummularia was grown in a split-root system for 21 d, with either the same or two different NaCl concentrations (ranging from 10 to 670 mm), in aerated nutrient solution bathing each root half. Key Results Non-uniform salinity, with high NaCl in one root half (up to 670 mm) and 10 mm in the other half, had no effect on shoot ethanol-insoluble dry mass, net photosynthesis or shoot pre-dawn water potential. In contrast, a modest effect occurred for leaf osmotic potential (up to 30 % more solutes compared with uniform 10 mm NaCl treatment). With non-uniform NaCl concentrations (10/670 mm), 90 % of water was absorbed from the low salinity side, and the reduction in water use from the high salinity side caused whole-plant water use to decrease by about 30 %; there was no compensatory water uptake from the low salinity side. Leaf Na+ and Cl− concentrations were 1·9- to 2·3-fold higher in the uniform 670 mm treatment than in the 10/670 mm treatment, whereas leaf K+ concentrations were 1·2- to 2·0-fold higher in the non-uniform treatment. Conclusions Atriplex nummularia with one root half in 10 mm NaCl maintained net photosynthesis, shoot growth and shoot water potential even when the other root half was exposed to 670 mm NaCl, a concentration that inhibits growth by 65 % when uniform in the root zone. Given the likelihood of non-uniform salinity in many field situations, this situation would presumably benefit halophyte growth and physiology in saline environments. PMID:19556265

Amelioration of boron toxicity in sweet pepper as affected by calcium management under an elevated CO2 concentration.

PubMed

Piñero, María Carmen; Pérez-Jiménez, Margarita; López-Marín, Josefa; Del Amor, Francisco M

2017-04-01

We investigated B tolerance in sweet pepper plants (Capsicum annuun L.) under an elevated CO 2 concentration, combined with the application of calcium as a nutrient management amelioration technique. The data show that high B affected the roots more than the aerial parts, since there was an increase in the shoot/root ratio, when plants were grown with high B levels; however, the impact was lessened when the plants were grown at elevated CO 2 , since the root FW reduction caused by excess B was less marked at the high CO 2 concentration (30.9% less). Additionally, the high B concentration affected the membrane permeability of roots, which increased from 39 to 54% at ambient CO 2 concentration, and from 38 to 51% at elevated CO 2 concentration, producing a cation imbalance in plants, which was differentially affected by the CO 2 supply. The Ca surplus in the nutrient solution reduced the nutritional imbalance in sweet pepper plants produced by the high B concentration, at both CO 2 concentrations. The medium B concentration treatment (toxic according to the literature) did not result in any toxic effect. Hence, there is a need to review the literature on critical and toxic B levels taking into account increases in atmospheric CO 2 .

The effect of multiple contamination of soil on LMW and MMW PAHs accumulation in the roots of Rubus fruticosus L. naturally growing near The Copper Mining and Smelting Complex Bor (East Serbia).

PubMed

Alagić, Slađana Č; Stankov Jovanović, Vesna P; Mitić, Violeta D; Nikolić, Jelena S; Petrović, Goran M; Tošić, Snežana B; Stojanović, Gordana S

2017-06-01

Samples of roots and spatial soils of native Rubus fruticosus L. were collected from the spots positioned at different distances from the copper smelter and city heating plants in the industrial zone of the town of Bor (Serbia) and subjected to chemical analyses in order to determine the content of several heavy metals, and 15 priority polycyclic aromatic hydrocarbons (PAHs). In this study, the results for 9 low and medium molecular weight PAHs (LMW and MMW PAHs) are represented and processed using the calculation of bio-concentration factors and statistical methods such as hierarchical cluster analysis and Pearson's correlation study with the aim of investigating the plant capabilities for their uptake from the soil and later accumulation into the root tissue, under the hostile circumstances of multiple contamination. The obtained data revealed different accumulation rates for the investigated PAHs and showed that in several cases, the contents of root PAHs were under the strong influence of present contaminants such as soil copper and some soil PAHs, indicating at the same time that R. fruticosus can regulate the processes of LMW and MMW PAHs extraction/accumulation using different mechanisms, depending on the existing environmental circumstances. The used mechanisms could be exploited in phytoremediation methods based not only on the extraction and concentration of PAHs in plant roots but also on PAH degradation or stabilization in the soil. Also, the results of this study confirmed that, except in the case of naphthalene and fluoranthene, there was no PAH pollution, which originated solely from the industrial zone.

Total mercury and methylmercury accumulation in wild plants grown at wastelands composed of mine tailings: Insights into potential candidates for phytoremediation.

PubMed

Qian, Xiaoli; Wu, Yonggui; Zhou, Hongyun; Xu, Xiaohang; Xu, Zhidong; Shang, Lihai; Qiu, Guangle

2018-08-01

Total mercury (THg) and methylmercury (MMHg) were investigated in 259 wild plants belonging to 49 species in 29 families that grew in heavily Hg-contaminated wastelands composed of cinnabar ore mine tailings (calcines) in the Wanshan region, southwestern China, the world's third largest Hg mining district. The bioconcentration factors (BCFs) of THg and MMHg from soil to roots ([THg] root /[THg] soil , [MMHg] root /[MMHg] soil ) were evaluated. The results showed that THg and MMHg in both plants and soils varied widely, with ranges of 0.076-140 μg/g THg and 0.19-87 ng/g MMHg in roots, 0.19-106 μg/g THg and 0.06-31 ng/g MMHg in shoots, and 0.74-1440 μg/g THg and 0.41-820 ng/g MMHg in soil. Among all investigated species, Arthraxon hispidus, Eremochloa ciliaris, Clerodendrum bunge, and Ixeris sonchifolia had significantly elevated concentrations of THg in shoots and/or roots that reached 100 μg/g, whereas Chenopodium glaucum, Corydalisedulis maxim, and Rumex acetosa contained low values below 0.5 μg/g. In addition to the high THg concentrations, the fern E. ciliaris also showed high BCF values for both THg and MMHg exceeding 1.0, suggesting its capability to extract Hg from soils. Considering its dominance and the tolerance identified in the present study, E. ciliaris is suggested to be a practical candidate for phytoextraction, whereas A. hispidus is identified as a potential candidate for phytostabilization of Hg mining-contaminated soils. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biochemical Composition Suggests Different Roles of Leaf Litter and Fine Roots in Soil Carbon Formation

NASA Astrophysics Data System (ADS)

Xia, M.; Pregitzer, K. S.; Talhelm, A. F.

2012-12-01

Plant litter is a major source of soil organic carbon (C). This litter is not homogenous, but instead primarily composed of fine root and leaf litter that adapted to different physiological functions. These unique functions suggest that root and leaf litter likely have different biochemical traits, and thus different decomposition patterns. However, few studies have compared their substrate quality and contributions to soil C. Also, much less attention has been given to fine roots although they can represent a substantial litter production. Here we hypothesize that 1) leaf litter and fine roots have different substrate quality as they are highly different in biochemical composition; 2) the biochemical composition of leaf litter and fine roots responds differently to the simulated nitrogen (N) deposition. To test these hypotheses, we collected leaf litter and fine roots of Acer saccharum (the dominant species in the northern temperate ecosystems we studied) in both ambient and N addition treatment plots at four sites of Michigan N deposition gradient study. We quantified ten biochemical components thought to be important on decomposition. Strikingly, we found a consistently three-fold higher lignin concentration in fine roots than that in leaf litter (P< 0.01). On average, lignin concentration of fine roots was 45.4±0.3% while that of leaf litter was 13.5±0.2%. Lignin has been considered highly recalcitrant and hypothesized as the major precursor of humus substance. Condensed tannin (CT) concentration in fine roots (13.13±0.51%) was also substantially higher than that in leaf litter (P< 0.01, 4.63±0.42 %). Tissue CT can inhibit litter decay by both precipitating proteins and by having antimicrobial properties. In contrast, fine roots exhibited lower concentrations of non-structural carbohydrates (NSC), soluble phenolics, and holocellulose (hemicelluloses & cellulose) than leaf litter (P< 0.01). These components are considered more easily accessible, and may stimulate the decay of lignin by providing required energy. Therefore, fine roots of Acer saccharum have a relatively recalcitrant nature based on their distinct biochemical composition, suggesting fine roots may be the major driver of soil carbon formation in the ecosystems we studied. Litter type and N addition had significant interactions on lignin, holocellulose, and NSC (P< 0.05), indicating these traits of different litter types respond differently to N addition. In leaf litter, the concentrations of lignin, NSC, and bound CT were affected by N addition (P< 0.05). By contrast, N addition only reduced the soluble protein concentration in fine roots (P< 0.05). Hence, substrate quality of leaf litter and fine roots responds differently to the simulated N deposition, and may eventually lead to different responses in decomposition pattern. This is one of few studies comparing the detailed biochemical profile of leaf litter and fine roots in a dominant tree species. Different biochemical traits of fine roots and leaf litter may reflect the different specializations for their physiological functions. This work highlights the importance of fine root in the soil carbon formation due to its recalcitrant nature, and emphasizes the necessity of differentiating the responses of leaf litter and fine root decompositions to environmental changes when modeling biogeochemical cycles.

Biogeochemistry of uranium in the soil-plant and water-plant systems in an old uranium mine.

PubMed

Favas, Paulo J C; Pratas, João; Mitra, Soumita; Sarkar, Santosh Kumar; Venkatachalam, Perumal

2016-10-15

The present study highlights the uranium (U) concentrations in water-soil-plant matrices and the efficiency considering a heterogeneous assemblage of terrestrial and aquatic native plant species to act as the biomonitor and phytoremediator for environmental U-contamination in the Sevilha mine (uraniferous region of Beiras, Central Portugal). A total of 53 plant species belonging to 22 families was collected from 24 study sites along with ambient soil and/or water samples. The concentration of U showed wide range of variations in the ambient medium: 7.5 to 557mgkg(-1) for soil and 0.4 to 113μgL(-1) for water. The maximum potential of U accumulation was recorded in roots of the following terrestrial plants: Juncus squarrosus (450mgkg(-1) DW), Carlina corymbosa (181mgkg(-1) DW) and Juncus bufonius (39.9mgkg(-1) DW), followed by the aquatic macrophytes, namely Callitriche stagnalis (55.6mgkg(-1) DW) Lemna minor (53.0mgkg(-1) DW) and Riccia fluitans (50.6mgkg(-1) DW). Accumulation of U in plant tissues exhibited the following decreasing trend: root>leaves>stem>flowers/fruits and this confirms the unique efficiency of roots in accumulating this radionuclide from host soil/sediment (phytostabilization). Overall, the accumulation pattern in the studied aquatic plants (L. minor, R. fluitans, C. stagnalis and Lythrum portula) dominated over most of the terrestrial counterpart. Among terrestrial plants, the higher mean bioconcentration factor (≈1 in roots/rhizomes of C. corymbosa and J. squarrosus) and translocation factor (31 in Andryala integrifolia) were encountered in the representing families Asteraceae and Juncaceae. Hence, these terrestrial plants can be treated as the promising candidates for the development of the phytostabilization or phytoextraction methodologies based on the accumulation, abundance and biomass production. Copyright © 2016 Elsevier B.V. All rights reserved.

DNA replication stress induces deregulation of the cell cycle events in root meristems of Allium cepa

PubMed Central

Żabka, Aneta; Polit, Justyna Teresa; Maszewski, Janusz

2012-01-01

Background and Aims Prolonged treatment of Allium cepa root meristems with changing concentrations of hydroxyurea (HU) results in either premature chromosome condensation or cell nuclei with an uncommon form of biphasic chromatin organization. The aim of the current study was to assess conditions that compromise cell cycle checkpoints and convert DNA replication stress into an abnormal course of mitosis. Methods Interphase-mitotic (IM) cells showing gradual changes of chromatin condensation were obtained following continuous 72 h treatment of seedlings with 0·75 mm HU (without renewal of the medium). HU-treated root meristems were analysed using histochemical stainings (DNA-DAPI/Feulgen; starch-iodide and DAB staining for H2O2 production), Western blotting [cyclin B-like (CBL) proteins] and immunochemistry (BrdU incorporation, detection of γ-H2AX and H3S10 phosphorylation). Key Results Continuous treatment of onion seedlings with a low concentration of HU results in shorter root meristems, enhanced production of H2O2, γ-phosphorylation of H2AX histones and accumulation of CBL proteins. HU-induced replication stress gives rise to axially elongated cells with half interphase/half mitotic structures (IM-cells) having both decondensed and condensed domains of chromatin. Long-term HU treatment results in cell nuclei resuming S phase with gradients of BrdU labelling. This suggests a polarized distribution of factors needed to re-initiate stalled replication forks. Furthermore, prolonged HU treatment extends both the relative time span and the spatial scale of H3S10 phosphorylation known in plants. Conclusions The minimum cell length and a threshold level of accumulated CBL proteins are both determining factors by which the nucleus attains commitment to induce an asynchronous course of chromosome condensation. Replication stress-induced alterations in an orderly route of the cell cycle events probably reflect a considerable reprogramming of metabolic functions of chromatin combined with gradients of morphological changes spread along the nucleus. PMID:23087128

Nitrogen metabolism of two contrasting poplar species during acclimation to limiting nitrogen availability

PubMed Central

Luo, Zhi-Bin

2013-01-01

To investigate N metabolism of two contrasting Populus species in acclimation to low N availability, saplings of slow-growing species (Populus popularis, Pp) and a fast-growing species (Populus alba × Populus glandulosa, Pg) were exposed to 10, 100, or 1000 μM NH4NO3. Despite greater root biomass and fine root surface area in Pp, lower net influxes of NH4 + and NO3 – at the root surface were detected in Pp compared to those in Pg, corresponding well to lower NH4 + and NO3 – content and total N concentration in Pp roots. Meanwhile, higher stable N isotope composition (δ15N) in roots and stronger responsiveness of transcriptional regulation of 18 genes involved in N metabolism were found in roots and leaves of Pp compared to those of Pg. These results indicate that the N metabolism of Pp is more sensitive to decreasing N availability than that of Pg. In both species, low N treatments decreased net influxes of NH4 + and NO3 –, root NH4 + and foliar NO3 – content, root NR activities, total N concentration in roots and leaves, and transcript levels of most ammonium (AMTs) and nitrate (NRTs) transporter genes in leaves and genes involved in N assimilation in roots and leaves. Low N availability increased fine root surface area, foliar starch concentration, δ15N in roots and leaves, and transcript abundance of several AMTs (e.g. AMT1;2) and NRTs (e.g. NRT1;2 and NRT2;4B) in roots of both species. These data indicate that poplar species slow down processes of N acquisition and assimilation in acclimation to limiting N supply. PMID:23963674

Accounting for sap flow from different parts of the root system improves the prediction of xylem ABA concentration in plants grown with heterogeneous soil moisture.

PubMed

Dodd, Ian C; Egea, Gregorio; Davies, William J

2008-01-01

When soil moisture is heterogeneous, sap flow from, and ABA status of, different parts of the root system impact on leaf xylem ABA concentration ([X-ABA]leaf). The robustness of a model for predicting [X-ABA]leaf was assessed. 'Two root-one shoot' grafted sunflower (Helianthus annuus L.) plants received either deficit irrigation (DI, each root system received the same irrigation volumes) or partial rootzone drying (PRD, only one root system was watered and the other dried the soil). Irrespective of whether relative sap flow was assessed using sap flow sensors in vivo or by pressurization of de-topped roots, each root system contributed similarly to total sap flow during DI, while sap flow from roots in drying soil declined linearly with soil water potential (Psisoil) during PRD. Although Psisoil of the irrigated pot determined the threshold Psisoil at which sap flow from roots in drying soil decreased, the slope of this decrease was independent of the wet pot Psisoil. Irrespective of whether sap was collected from the wet or dry root system of PRD plants, or a DI plant, root xylem ABA concentration increased as Psisoil declined. The model, which weighted ABA contributions of each root system according to the sap flow from each, almost perfectly explained [X-ABA] immediately above the graft union. That the model overestimated measured [X-ABA]leaf may result from changes in [X-ABA] along the transport pathway or an artefact of collecting xylem sap from detached leaves. The implications of declining sap flow through partially dry roots during PRD for the control of stomatal behaviour and irrigation scheduling are discussed.

Phytotoxic and genotoxic effects of ZnO nanoparticles on garlic (Allium sativum L.): a morphological study.

PubMed

Shaymurat, Talgar; Gu, Jianxiu; Xu, Changshan; Yang, Zhikun; Zhao, Qing; Liu, Yuxue; Liu, Yichun

2012-05-01

The effects of zinc oxide nanoparticles (ZnO NPs) on the root growth, root apical meristem mitosis and mitotic aberrations of garlic (Allium sativum L.) were investigated. ZnO NPs caused a concentration-dependent inhibition of root length. When treated with 50 mg/L ZnO NPs for 24 h, the root growth of garlic was completely blocked. The 50% inhibitory concentration (IC(50)) was estimated to be 15 mg/L. The mitosis index was also decreased in a concentration- and time-dependent manner. ZnO NPs also induced several kinds of mitotic aberrations, mainly consisted of chromosome stickiness, bridges, breakages and laggings. The total percentage of abnormal cells increased with the increase of ZnO NPs concentration and the prolongation of treatment time. The investigation provided new information for the possible genotoxic effects of ZnO NPs on plants.

Early Detection of Salt Stress Damage by Biophotons in Red Bean Seedling

NASA Astrophysics Data System (ADS)

Ohya, Tomoyuki; Kurashige, Hideaki; Okabe, Hirotaka; Kai, Shoichi

2000-06-01

The optical detection of the stress damage to plants by NaCl solutions was attempted during germination of a seed and growth of a root. We compared the photon intensity of red beans before and after NaCl treatment and found that the photon intensity after NaCl treatment decreased as the NaCl concentration increased. For the saturated NaCl concentration (4.5 M), however, the observed photon intensity drastically increased, and the simultaneous destruction of cell membranes was observed. The intensity of biophoton emission from red beans showed characteristic change with salt concentrations. When the salt stress was applied to the red beans at an early growth stage, their root elongations were suppressed and photon intensity from the root decreased. This was not the case for the root at the late stage. This shows that biophoton intensity due to salt stress depends on not only NaCl concentration but also the growth stage of the plant. We may conclude that the extent of damage to roots by salt stress can be evaluated from biophoton response.

Absorption and translocation of nitrogen in rhizomes of Leymus chinensis.

PubMed

Liu, Hongsheng; Liu, Huajie; Song, Youhong

2011-03-15

Leymus chinensis is a dominant species in the Inner Mongolia steppe, northern China. Plant growth in northern China grassland is often limited by low soil nitrogen availability. The objective of this study is to investigate whether rhizomes of Leymus chinensis are involved in the contribution of N uptake. The N concentration, (15)N concentration and (15)N proportion in roots, rhizomes and shoots after 48 h exposure of roots (L(root)) and rhizomes (L(rhizo)) separately and roots and rhizomes together (L(r+r)) to 0.1 mM (15)NH (4)(15)NO(3) solution were measured using root-splitting equipment and stable isotope ((15)N) techniques, respectively. The N content and dry mass were not affected by the labeling treatment. In contrast, the (15)N concentration in shoots, rhizomes and roots was significantly increased by the labeling in rhizomes, indicating that the inorganic nitrogen was absorbed via rhizomes from the solution and can be transported to other tissues, with preference to shoots rather than roots. Meanwhile, the absolute N absorption and translocation among compartments were also calculated. The N absorption via rhizomes was much smaller than via roots; however, the uptake efficiency per surface unit via rhizomes was greater than via roots. The capacity and high efficiency to absorb N nutrient via rhizomes enable plants to use transient nutrient supplies in the top soil surface. Copyright © 2011 John Wiley & Sons, Ltd.

Influence of cadmium on antioxidant capacity and four microelement concentrations in tomato seedlings (Lycopersicon esculentum).

PubMed

Dong, Jing; Wu, Feibo; Zhang, Guoping

2006-09-01

Tomato (Lycopersicon esculentum) seedlings were grown in four cadmium (Cd) levels of 0-10 microM in a hydroponic system to analyze the antioxidative enzymes, Cd concentration in the plants, and the interaction between Cd and four microelements. The results showed that there was a significant increase in malondialdehyde (MDA) concentration, and superoxide dismutase (SOD) and peroxidase (POD) activities in the plants subjected to 1-10 microM Cd. This indicates that Cd stress induces an oxidative stress response in tomato plants, characterized by an accumulation of MDA and increase in activities of SOD and POD. Root, stem and leaf Cd concentrations increased with its exposure Cd level, and the highest Cd concentration occurred in roots, followed by leaves and stems. A concentration- and tissue-dependent response was found in the four microelement concentrations to Cd stress in the tomato leaves, stems and roots. Regression analysis showed that there was a significantly negative correlation between Cd and Mn, implying the antagonistic effect of Cd on Mn absorption and translocation. The correlation between Cd and Zn, Cu and Fe were inconsistent among leaves, stems and roots.

Influence of iron plaque on uptake and accumulation of Cd by rice (Oryza sativa L.) seedlings grown in soil.

PubMed

Liu, Houjun; Zhang, Junling; Christie, Peter; Zhang, Fusuo

2008-05-15

Iron plaque is ubiquitously formed on the root surfaces of rice. However, little is known about the role of iron plaque in Cd movement from soil to the plant aboveground parts. A pot experiment was conducted to investigate the influence of iron plaque in Cd uptake and accumulation by rice seedlings in soil. Rice seedlings were pre-cultivated in solution culture for 16 days. Two seedlings were transplanted in a nylon bag containing no substrate but surrounded by soil amended with Fe and Cd combined at rates of 0, 1, or 2 g Fe kg(-1) and 0, 2.0, or 10 mg Cd kg(-1) soil. Fe was added to induce different amounts of iron plaque, and Cd to simulate Cd-polluted soils. Plants were grown for a further 43 days and then harvested. The length of the longest leaf and SPAD values of the newly mature leaves were measured during plant growth. Fe and Cd concentrations were determined in dithionite-citrate-bicarbonate (DCB) soil extracts and in plant roots and shoots. Shoot and root dry weights were significantly affected by Fe supply level but not by added Cd. Root dry weight declined with increasing Fe supply but shoot dry weight decreased at 2 g Fe kg(-1) and increased at 1 g Fe kg(-1) (except at 2 mg Cd kg(-1)). The length of the longest leaf and SPAD values of the newly mature leaves were significantly affected by plant growth stage and added Fe and Cd. Fe tended to diminish the negative effect of Cd on these two parameters. Cd concentrations in DCB extracts increased with increasing Cd and Fe supply. In contrast, external Fe supply markedly reduced shoot and root Cd concentrations and there was generally no significant difference between the two Fe supply levels. Shoot and root Cd concentrations increased with increasing Cd addition. Root Cd concentrations were negatively correlated with root Fe concentrations. The proportion of Cd in DCB extracts was significantly lower than in roots or shoots. The results indicate that enhanced Fe uptake by plants can diminish the negative effects of Cd to some extent and that iron plaque on root surfaces is of little significance in affecting uptake and accumulation of Cd by rice plants.

Ramie (Boehmeria nivea)'s uranium bioconcentration and tolerance attributes.

PubMed

Wang, Wei-Hong; Luo, Xue-Gang; Liu, Lai; Zhang, Yan; Zhao, Hao-Zhou

2018-04-01

The authors sampled and analyzed 15 species of dominant wild plants in Huanan uranium tailings pond in China, whose tailings' uranium contents were 3.21-120.52 μg/g. Among the 15 species of wild plants, ramie (Boehmeria nivea) had the strongest uranium bioconcentration and transfer capacities. In order to study the uranium bioconcentration and tolerance attributes of ramie in detail, and provide a reference for the screening remediation plants to phytoremedy on a large scale in uranium tailings pond, a ramie cultivar Xiangzhu No. 7 pot experiment was carried out. We found that both wild ramie and Xiangzhu No. 7 could bioconcentrate uranium, but there were two differences. One was wild ramie's shoots bioconcentrated uranium up to 20 μg/g (which can be regarded as the critical content value of the shoot of uranium hyperaccumulator) even the soil uranium content was as low as 5.874 μg/g while Xiangzhu No. 7's shoots could reach 20 μg/g only when the uranium treatment concentrations were 275 μg/g or more; the other was that all the transfer factors of 3 wild samples were >1, and the transfer factors of 27 out of 28 pot experiment samples were <1. Probably wild ramie was a uranium hyperaccumulator. Xiangzhu No. 7 satisfied the needs of uranium hyperaccumulator on accumulation capability, tolerance capability, bioconcentration factor, but not transfer capability, so Xiangzhu No. 7 was not a uranium hyperaccumulator. We analyzed the possible reasons why there were differences in the uranium bioconcentration and transfer attributes between wild ramie and Xiangzhu No. 7., and proposed the direction for further research. In our opinion, both the plants which bioconcentrate contaminants in the shoots and roots can act as phytoextractors. Although Xiangzhu No. 7's biomass and accumulation of uranium were concentrated on the roots, the roots were small in volume and easy to harvest. And Xiangzhu No. 7's cultivating skills and protection measures had been developed very well. Xiangzhu No. 7's whole bioconcentration factors and the roots' bioconcentration factors, which were 1.200-1.834 and 1.460-2.341, respectively, increased with the increases of uranium contents of pot soil when the soil's uranium contents are 25-175 μg/g, so it can act as a potential phytoextractor when Huanan uranium tailings pond is phytoremediated. Copyright © 2018. Published by Elsevier Ltd.

Tracking Se Assimilation and Speciation through the Rice Plant – Nutrient Competition, Toxicity and Distribution

PubMed Central

Eiche, Elisabeth; Riemann, Michael; Nick, Peter; Winkel, Lenny H. E.; Göttlicher, Jörg; Steininger, Ralph; Brendel, Rita; von Brasch, Matthias; Konrad, Gabriele; Neumann, Thomas

2016-01-01

Up to 1 billion people are affected by low intakes of the essential nutrient selenium (Se) due to low concentrations in crops. Biofortification of this micronutrient in plants is an attractive way of increasing dietary Se levels. We investigated a promising method of Se biofortification of rice seedlings, as rice is the primary staple for 3 billion people, but naturally contains low Se concentrations. We studied hydroponic Se uptake for 0–2500 ppb Se, potential phyto-toxicological effects of Se and the speciation of Se along the shoots and roots as a function of added Se species, concentrations and other nutrients supplied. We found that rice germinating directly in a Se environment increased plant-Se by factor 2–16, but that nutrient supplementation is required to prevent phyto-toxicity. XANES data showed that selenite uptake mainly resulted in the accumulation of organic Se in roots, but that selenate uptake resulted in accumulation of selenate in the higher part of the shoot, which is an essential requirement for Se to be transported to the grain. The amount of organic Se in the plant was positively correlated with applied Se concentration. Our results indicate that biofortification of seedlings with selenate is a successful method to increase Se levels in rice. PMID:27116220

Interactions among cluster-root investment, leaf phosphorus concentration, and relative growth rate in two Lupinus species.

PubMed

Wang, Xing; Veneklaas, Erik J; Pearse, Stuart J; Lambers, Hans

2015-09-01

Cluster-root (CR) formation is a desirable trait to improve phosphorus (P) acquisition as global P resources are dwindling. CRs in some lupine species are suppressed at higher P status. Whether increased growth rate enhances CR formation due to a "dilution" of leaf P concentration is unknown. We investigated interactive effects of leaf P status and relative growth rate (RGR) on CR formation in two Lupinus species, which differ in their CR biomass investment. Variation in RGR was imposed by varying day length. Lupinus albus and L. pilosus were grown hydroponically with KH2PO4 at a day length of 6, 10, or 14 h. We used a slightly higher P supply at longer day lengths to avoid a decline in leaf P concentration, which would induce CRs. Cluster-root percentage, leaf P concentrations, and RGR were determined at 22, 38, and 52 d after sowing. Lupinus species grown at similar root P availability, but with a faster growth rate, as dependent on day length, showed a greater CR percentage. Because our aim to achieve exactly the same leaf P concentrations at different day lengths was only partially achieved, we carried out a multiple regression analysis. This analysis showed the CR percentage was strongly and negatively correlated with plant P status and only marginally and positively correlated with RGR. The two Lupinus species invariably formed fewer cluster roots at higher leaf P status, irrespective of RGR. Differences in RGR or leaf P concentration cannot explain the species-specific variation in cluster-root investment. © 2015 Botanical Society of America.

Effects of non-uniform root zone salinity on water use, Na+ recirculation, and Na+ and H+ flux in cotton

PubMed Central

Kong, Xiangqiang; Luo, Zhen; Dong, Hezhong; Eneji, A. Egrinya

2012-01-01

A new split-root system was established through grafting to study cotton response to non-uniform salinity. Each root half was treated with either uniform (100/100 mM) or non-uniform NaCl concentrations (0/200 and 50/150 mM). In contrast to uniform control, non-uniform salinity treatment improved plant growth and water use, with more water absorbed from the non- and low salinity side. Non-uniform treatments decreased Na+ concentrations in leaves. The [Na+] in the ‘0’ side roots of the 0/200 treatment was significantly higher than that in either side of the 0/0 control, but greatly decreased when the ‘0’ side phloem was girdled, suggesting that the increased [Na+] in the ‘0’ side roots was possibly due to transportation of foliar Na+ to roots through phloem. Plants under non-uniform salinity extruded more Na+ from the root than those under uniform salinity. Root Na+ efflux in the low salinity side was greatly enhanced by the higher salinity side. NaCl-induced Na+ efflux and H+ influx were inhibited by amiloride and sodium orthovanadate, suggesting that root Na+ extrusion was probably due to active Na+/H+ antiport across the plasma membrane. Improved plant growth under non-uniform salinity was thus attributed to increased water use, reduced leaf Na+ concentration, transport of excessive foliar Na+ to the low salinity side, and enhanced Na+ efflux from the low salinity root. PMID:22200663

Extracellular ATP inhibits root gravitropism at concentrations that inhibit polar auxin transport

NASA Technical Reports Server (NTRS)

Tang, Wenqiang; Brady, Shari R.; Sun, Yu; Muday, Gloria K.; Roux, Stanley J.

2003-01-01

Raising the level of extracellular ATP to mM concentrations similar to those found inside cells can block gravitropism of Arabidopsis roots. When plants are grown in Murashige and Skoog medium supplied with 1 mM ATP, their roots grow horizontally instead of growing straight down. Medium with 2 mM ATP induces root curling, and 3 mM ATP stimulates lateral root growth. When plants are transferred to medium containing exogenous ATP, the gravity response is reduced or in some cases completely blocked by ATP. Equivalent concentrations of ADP or inorganic phosphate have slight but usually statistically insignificant effects, suggesting the specificity of ATP in these responses. The ATP effects may be attributable to the disturbance of auxin distribution in roots by exogenously applied ATP, because extracellular ATP can alter the pattern of auxin-induced gene expression in DR5-beta-glucuronidase transgenic plants and increase the response sensitivity of plant roots to exogenously added auxin. The presence of extracellular ATP also decreases basipetal auxin transport in a dose-dependent fashion in both maize (Zea mays) and Arabidopsis roots and increases the retention of [(3)H]indole-3-acetic acid in root tips of maize. Taken together, these results suggest that the inhibitory effects of extracellular ATP on auxin distribution may happen at the level of auxin export. The potential role of the trans-plasma membrane ATP gradient in auxin export and plant root gravitropism is discussed.

Accumulation of cadmium, zinc, and copper by Helianthus annuus L.: impact on plant growth and uptake of nutritional elements.

PubMed

Rivelli, Anna Rita; De Maria, Susanna; Puschenreiter, Markus; Gherbin, Piergiorgio

2012-04-01

We investigated the effects on physiological response, trace elements and nutrients accumulation of sunflower plants grown in soil contaminated with: 5 mg kg(-1) of Cd; 5 and 300 mg kg(-1) of Cd and Zn, respectively; 5, 300, and 400 mg kg(-1) of Cd, Zn, and Cu, respectively. Contaminants applied did not produce large effects on growth, except in Cd-Zn-Cu treatment in which leaf area and total dry matter were reduced, by 15%. The contamination with Cd alone did not affect neither growth nor physiological parameters, despite considerable amounts of Cd accumulated in roots and older leaves, with a high bioconcentration factor from soil to plant. By adding Zn and then Cu to Cd in soil, significant were the toxic effects on chlorophyll content and water relations due to greater accumulation of trace elements in tissues, with imbalances in nutrients uptake. Highly significant was the interaction between shoot elements concentration (Cd, Zn, Cu, Fe, Mg, K, Ca) and treatments. Heavy metals concentrations in roots always exceeded those in stem and leaves, with a lower translocation from roots to shoots, suggesting a strategy of sunflower to compartmentalise the potentially toxic elements in physiologically less active parts in order to preserve younger tissues.

Effects of Irrigation with Treated Wastewater on Root and Fruit Mineral Elements of Chemlali Olive Cultivar

PubMed Central

Bedbabis, Saida; Ben Rouina, Béchir; Boukhris, Makki

2014-01-01

Twenty-year-old “Chemlali” olive trees trained to vase and rainfed were investigated in either “on” (2004) or “off” (2003) year. A randomized block design with three blocks and three treatments was used and each experimental plot consisted of nine olive trees. Three treatments were applied: (1) rainfed conditions (RF, used as control treatment); (2) irrigation with well water (WW); and (3) irrigation with treated wastewater (TWW). Irrigation with TWW led to a significant increase of root N, P, Ca, Zn, Mn, Na, and Cl concentrations, in particular in the on-year. Data showed significant differences, between the two years, for the concentration of the mineral elements in the roots, with general lower values in the on-year, probably as a consequence of nutrients movement upward in the tree. Fruit N, P, K, Zn, Mn, and Cl contents were significantly higher in TWW irrigated trees with respect to both RF and WW trees, whereas similar values for Ca, Mg, Na, and Cl contents were measured for WW and TWW irrigated trees. The irrigation with TWW allowed to reuse problematic waters and to save nutrients inputs in the olive orchard thus moving towards a more sustainable management of olive orchards in countries where water is the major limiting factor for agriculture. PMID:25013873

Uranium fate in wetland mesocosms: Effects of plants at two iron loadings with different pH values.

PubMed

Koster van Groos, Paul G; Kaplan, Daniel I; Chang, Hyun-Shik; Seaman, John C; Li, Dien; Peacock, Aaron D; Scheckel, Kirk G; Jaffé, Peter R

2016-11-01

Small-scale continuous flow wetland mesocosms (∼0.8 L) were used to evaluate how plant roots under different iron loadings affect uranium (U) mobility. When significant concentrations of ferrous iron (Fe) were present at circumneutral pH values, U concentrations in root exposed sediments were an order of magnitude greater than concentrations in root excluded sediments. Micro X-ray absorption near-edge structure (μ-XANES) spectroscopy indicated that U was associated with the plant roots primarily as U(VI) or U(V), with limited evidence of U(IV). Micro X-ray fluorescence (μ-XRF) of plant roots suggested that for high iron loading at circumneutral pH, U was co-located with Fe, perhaps co-precipitated with root Fe plaques, while for low iron loading at a pH of ∼4 the correlation between U and Fe was not significant, consistent with previous observations of U associated with organic matter. Quantitative PCR analyses indicated that the root exposed sediments also contained elevated numbers of Geobacter spp., which are likely associated with enhanced iron cycling, but may also reduce mobile U(VI) to less mobile U(IV) species. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nanoscale measurement of trace element distributions in Spartina alterniflora root tissue during dormancy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Huan; Qian, Yu; Cochran, J. Kirk

Here, this article reports a nanometer-scale investigation of trace element (As, Ca, Cr, Cu, Fe, Mn, Ni, S and Zn) distributions in the root system Spartina alterniflora during dormancy. The sample was collected on a salt marsh island in Jamaica Bay, New York, in April 2015 and the root was cross-sectioned with 10 μm resolution. Synchrotron X-ray nanofluorescence was applied to map the trace element distributions in selected areas of the root epidermis and endodermis. The sampling resolution was 60 nm to increase the measurement accuracy and reduce the uncertainty. The results indicate that the elemental concentrations in the epidermis,more » outer endodermis and inner endodermis are significantly (p < 0.01) different. The root endodermis has relatively higher concentrations of these elements than the root epidermis. Furthermore, this high resolution measurement indicates that the elemental concentrations in the outer endodermis are significantly (p < 0.01) higher than those in the inner endodermis. These results suggest that the Casparian strip may play a role in governing the aplastic transport of these elements. Pearson correlation analysis on the average concentrations of each element in the selected areas shows that most of the elements are significantly (p < 0.05) correlated, which suggests that these elements may share the same transport pathways.« less

Nanoscale measurement of trace element distributions in Spartina alterniflora root tissue during dormancy

DOE PAGES

Feng, Huan; Qian, Yu; Cochran, J. Kirk; ...

2017-01-18

Here, this article reports a nanometer-scale investigation of trace element (As, Ca, Cr, Cu, Fe, Mn, Ni, S and Zn) distributions in the root system Spartina alterniflora during dormancy. The sample was collected on a salt marsh island in Jamaica Bay, New York, in April 2015 and the root was cross-sectioned with 10 μm resolution. Synchrotron X-ray nanofluorescence was applied to map the trace element distributions in selected areas of the root epidermis and endodermis. The sampling resolution was 60 nm to increase the measurement accuracy and reduce the uncertainty. The results indicate that the elemental concentrations in the epidermis,more » outer endodermis and inner endodermis are significantly (p < 0.01) different. The root endodermis has relatively higher concentrations of these elements than the root epidermis. Furthermore, this high resolution measurement indicates that the elemental concentrations in the outer endodermis are significantly (p < 0.01) higher than those in the inner endodermis. These results suggest that the Casparian strip may play a role in governing the aplastic transport of these elements. Pearson correlation analysis on the average concentrations of each element in the selected areas shows that most of the elements are significantly (p < 0.05) correlated, which suggests that these elements may share the same transport pathways.« less

Knockdown of the partner protein OsNAR2.1 for high-affinity nitrate transport represses lateral root formation in a nitrate-dependent manner

PubMed Central

Huang, Shuangjie; Chen, Si; Liang, Zhihao; Zhang, Chenming; Yan, Ming; Chen, Jingguang; Xu, Guohua; Fan, Xiaorong; Zhang, Yali

2015-01-01

The morphological plasticity of root systems is critical for plant survival, and understanding the mechanisms underlying root adaptation to nitrogen (N) fluctuation is critical for sustainable agriculture; however, the molecular mechanism of N-dependent root growth in rice remains unclear. This study aimed to identify the role of the complementary high-affinity NO3− transport protein OsNAR2.1 in NO3−-regulated rice root growth. Comparisons with wild-type (WT) plants showed that knockdown of OsNAR2.1 inhibited lateral root (LR) formation under low NO3− concentrations, but not under low NH4+ concentrations. 15N-labelling NO3− supplies (provided at concentrations of 0–10 mM) demonstrated that (i) defects in LR formation in mutants subjected to low external NO3− concentrations resulted from impaired NO3− uptake, and (ii) the mutants had significantly fewer LRs than the WT plants when root N contents were similar between genotypes. LR formation in osnar2.1 mutants was less sensitive to localised NO3− supply than LR formation in WT plants, suggesting that OsNAR2.1 may be involved in a NO3−-signalling pathway that controls LR formation. Knockdown of OsNAR2.1 inhibited LR formation by decreasing auxin transport from shoots to roots. Thus, OsNAR2.1 probably functions in both NO3− uptake and NO3−-signalling. PMID:26644084

Evidence that elevated CO2 levels can indirectly increase rhizosphere denitrifier activity

NASA Technical Reports Server (NTRS)

Smart, D. R.; Ritchie, K.; Stark, J. M.; Bugbee, B.

1997-01-01

We examined the influence of elevated CO2 concentration on denitrifier enzyme activity in wheat rhizoplanes by using controlled environments and solution culture techniques. Potential denitrification activity was from 3 to 24 times higher on roots that were grown under an elevated CO2 concentration of 1,000 micromoles of CO2 mol-1 than on roots grown under ambient levels of CO2. Nitrogen loss, as determined by a nitrogen mass balance, increased with elevated CO2 levels in the shoot environment and with a high NO3- concentration in the rooting zone. These results indicated that aerial CO2 concentration can play a role in rhizosphere denitrifier activity.

The use of Eupatorium Odoratum as bio-monitor for radionuclides determination in Manjung, Perak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zainal, Fetri, E-mail: fetrizainal@yahoo.com; Hamzah, Zaini; Wood, Khalik

2015-04-29

The accumulation of radionuclides in plants can be used as bio-monitoring in the environment. This technique is a cost-effective as the plants used to uptake deposited radionuclides from soil, commonly as soil-to-plant transfer factor (TF), which is widely used for calculating radiological risk. Radionuclides deposited in the soil carry by the air as particles or gases lead to the accumulation in soil. Eupatorium odoratum, known as pokok kapal terbang in Malaysia was chosen as sample for their abundances and properties to measure surface soil contamination. The plants were collected in three different directions (North, North-East and South-East) from Manjung district.more » The plants were collected in same size and then separated in to three parts (roots, stems and leaves) to determine the transfer factor from soil to each part. The concentrations of thorium (Th) and uranium (U) were analyzed using Energy Disperse X-Ray Fluorescence (EDXRF) and found in the range of 1.20-3.50 mg/kg and 1.20-3.90 mg/kg in roots, 1.40-3.90 mg/kg and 1.50-5.90 mg/kg in stems and 1.50-2.50 mg/kg and 2.00-6.00 mg/kg in leaves, respectively. Transfer factor (TF) was calculated through concentrations as reported in this article and show that the plants have transferred and accumulated radionuclides in significant values. From radionuclides concentrations in topsoil, the radiological risk was calculated and the present result show that external hazard index (H{sub ex}) is below than unity indicate low radiological risk at that area.« less

Effect of elevated CO2 on phosphorus nutrition of phosphate-deficient Arabidopsis thaliana (L.) Heynh under different nitrogen forms

PubMed Central

Niu, Yaofang; Chai, Rushan; Zhang, Yongsong

2013-01-01

Phosphorus (P) nutrition is always a key issue regarding plants responses to elevated CO2. Yet it is unclear of how elevated CO2 affects P uptake under different nitrogen (N) forms. This study investigated the influence of elevated CO2 (800 µl l–1) on P uptake and utilization by Arabidopsis grown in pH-buffered phosphate (P)-deficient (0.5 µM) hydroponic culture supplying with 2mM nitrate (NO3 −) or ammonium (NH4 +). After 7 d treatment, elevated CO2 enhanced the biomass production of both NO3 −- and NH4 +-fed plants but decreased the P amount absorbed per weight of roots and the P concentration in the shoots of plants supplied with NH4 +. In comparison, elevated CO2 increased the amount of P absorbed per weight of roots, as well as the P concentration in plants and alleviated P deficiency-induced symptoms of plants supplied with NO3 −. Elevated CO2 also increased the root/shoot ratio, total root surface area, and acid phosphatase activity, and enhanced the expression of genes or transcriptional factors involving in P uptake, allocation and remobilization in P deficient plants. Furthermore, elevated CO2 increased the nitric oxide (NO) level in roots of NO3 −-fed plants but decreased it in NH4 +-fed plants. NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) inhibited plant P acquisition by roots under elevated CO2. Considering all of these findings, this study concluded that a combination of elevated CO2 and NO3 − nutrition can induce a set of plant adaptive strategies to improve P status from P-deficient soluble sources and that NO may be a signalling molecule that controls these processes. PMID:23183255

Variations in metal tolerance and accumulation in three hydroponically cultivated varieties of Salix integra treated with lead.

PubMed

Wang, Shufeng; Shi, Xiang; Sun, Haijing; Chen, Yitai; Pan, Hongwei; Yang, Xiaoe; Rafiq, Tariq

2014-01-01

Willow species have been suggested for use in the remediation of contaminated soils due to their high biomass production, fast growth, and high accumulation of heavy metals. The tolerance and accumulation of metals may vary among willow species and varieties, and the assessment of this variability is vital for selecting willow species/varieties for phytoremediation applications. Here, we examined the variations in lead (Pb) tolerance and accumulation of three cultivated varieties of Salix integra (Weishanhu, Yizhibi and Dahongtou), a shrub willow native to northeastern China, using hydroponic culture in a greenhouse. In general, the tolerance and accumulation of Pb varied among the three willow varieties depending on the Pb concentration. All three varieties had a high tolerance index (TI) and EC50 value (the effective concentration of Pb in the nutrient solution that caused a 50% inhibition on biomass production), but a low translocation factor (TF), indicating that Pb sequestration is mainly restricted in the roots of S. integra. Among the three varieties, Dahogntou was more sensitive to the increased Pb concentration than the other two varieties, with the lowest EC50 and TI for root and above-ground tissues. In this respect, Weishanhu and Yizhibi were more suitable for phytostabilization of Pb-contaminated soils. However, our findings also indicated the importance of considering the toxicity symptoms when selecting willow varieties for the use of phytoremediation, since we also found that the three varieties revealed various toxicity symptoms of leaf wilting, chlorosis and inhibition of shoot and root growth under the higher Pb concentrations. Such symptoms could be considered as a supplementary index in screening tests.

Variations in Metal Tolerance and Accumulation in Three Hydroponically Cultivated Varieties of Salix integra Treated with Lead

PubMed Central

Sun, Haijing; Chen, Yitai; Pan, Hongwei; Yang, Xiaoe; Rafiq, Tariq

2014-01-01

Willow species have been suggested for use in the remediation of contaminated soils due to their high biomass production, fast growth, and high accumulation of heavy metals. The tolerance and accumulation of metals may vary among willow species and varieties, and the assessment of this variability is vital for selecting willow species/varieties for phytoremediation applications. Here, we examined the variations in lead (Pb) tolerance and accumulation of three cultivated varieties of Salix integra (Weishanhu, Yizhibi and Dahongtou), a shrub willow native to northeastern China, using hydroponic culture in a greenhouse. In general, the tolerance and accumulation of Pb varied among the three willow varieties depending on the Pb concentration. All three varieties had a high tolerance index (TI) and EC50 value (the effective concentration of Pb in the nutrient solution that caused a 50% inhibition on biomass production), but a low translocation factor (TF), indicating that Pb sequestration is mainly restricted in the roots of S. integra. Among the three varieties, Dahogntou was more sensitive to the increased Pb concentration than the other two varieties, with the lowest EC50 and TI for root and above-ground tissues. In this respect, Weishanhu and Yizhibi were more suitable for phytostabilization of Pb-contaminated soils. However, our findings also indicated the importance of considering the toxicity symptoms when selecting willow varieties for the use of phytoremediation, since we also found that the three varieties revealed various toxicity symptoms of leaf wilting, chlorosis and inhibition of shoot and root growth under the higher Pb concentrations. Such symptoms could be considered as a supplementary index in screening tests. PMID:25268840

Screening the phytoremediation potential of desert broom (Baccharis sarothroides Gray) growing on mine tailings in Arizona, USA

PubMed Central

Haque, Nazmul; Peralta-Videa, Jose R.; Jones, Gary L.; Gill, Thomas E.; Gardea-Torresdey, Jorge L.

2008-01-01

The metal concentrations in a copper mine tailings and Desert broom (Baccharis sarothroides Gray) plants were investigated. The metal concentrations in plants, soil cover, and tailings were determined using ICP-OES. The concentration of copper, lead, molybdenum, chromium, zinc, arsenic, nickel, and cobalt in tailings was 526.4, 207.4, 89.1, 84.5, 51.7, 49.6, 39.7, and 35.6 mg kg−1, respectively. The concentration of all elements in soil cover was 10~15% higher than that of the tailings, except for molybdenum. The concentration of copper, lead, molybdenum, chromium, zinc, arsenic, nickel, and cobalt in roots was 818.3, 151.9, 73.9, 57.1, 40.1, 44.6, 96.8, and 26.7 mg kg−1 and 1214.1, 107.3, 105.8, 105.5, 55.2, 36.9, 30.9, and 10.9 mg kg−1 for shoots, respectively. Considering the translocation factor, enrichment coefficient, and the accumulation factor, desert broom could be a potential hyperaccumulator of Cu, Pb, Cr, Zn, As, and Ni. PMID:17964035

Hyperaccumulation of cadmium by hairy roots of Thlaspi caerulescens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nedelkoska, T.V.; Doran, P.M.

Hairy roots were used to investigate cadmium uptake by Thlaspi caerulescens, a metal hyperaccumulator plant with potential applications in phytoremediation and phytomining. Experiments were carried out in nutrient media under conditions supporting root growth. Accumulation of Cd in short-term (9-h) experiments varied with initial medium pH and increased after treating the roots with H{sup +}-ATPase inhibitor. The highest equilibrium Cd content measured in T. caerulescens roots was 62,800 {micro}g g{sup {minus}1} dry weight, or 6.3% dry weight, at a liquid Cd concentration of 3,710 ppm. Cd levels in live T. caerulescens roots were 1.5- to 1.7-fold those in hairy rootsmore » of nonhyperaccumulator species exposed to the same Cd concentration, but similar to the Cd content of auto-claved T. caerulescens roots. The ability to grow at Cd concentrations of up to 100 ppm clearly distinguished T. caerulescens hairy roots from the nonhyperaccumulators. The specific growth rate of T. caerulescens roots was essentially unaffected by 20 to 50 ppm Cd in the culture medium; in contrast, N. tabacum roots turned dark brown at 20 ppm and growth was negligible. Up to 10,600 {micro}g g{sup {minus}1} dry weight Cd was accumulated by growing T. caerulescens hairy roots. Measurement of Cd levels in while roots and in the cell wall fraction revealed significant differences in the responses of T. caerulescens and N. tabacum roots to 20 ppm Cd. Most metal was transported directly into the symplasm of N. tabacum roots within 3 days of exposure; in contrast, T. caerulescens roots stored virtually all of their Cd in the wall fraction for the first 7 to 10 days. This delay in transmembrane uptake may represent an important defensive strategy against Cd poisoning in T. caerulescens, allowing time for activation of intracellular mechanisms for heavy metal detoxification.« less

[Environment spatial distribution of mercury pollution in Songhua River upstream gold mining areas].

PubMed

Zou, Ting-Ting; Wang, Ning; Zhang, Gang; Zhao, Dan-Dan

2010-09-01

Using Zeeman mercury spectrometer RA915+ monitoring the total gaseous mercury concentration were collected from gold mining area in Huadian, in the upper reaches of the Songhua River, during summer and autumn of 2008, where we simultaneously collected samples of air, water, sediment and soil. The research is focused on analyzing of the spatial and temporal distribution characteristics of atmospheric mercury pollution and the correlation with other environmental factors. The results show that: the concentration of atmospheric mercury in summer is higher than that in autumn and in the evening is higher than at noon, and it present a gradual decay with the distance to the gold mining area as the center point increasing. The distribution rule of mercury pollution of environmental factors in the gold mining area is: in sediment > in soil > in plant > in water, the characteristics of mercury pollution distribution in plant is: root > stem and leaf, and the content of mercury in plant in autumn is commonly higher than that in summer. This is thought due to the accumulation of pollutant element from soil during the growth of plant. The atmospheric mercury has a significant correlation with the root of plant, respectively 0.83 in summer and 0.97 in autumn.

Response difference of transgenic and conventional rice (Oryza sativa) to nanoparticles (γFe₂O₃).

PubMed

Gui, Xin; Deng, Yingqing; Rui, Yukui; Gao, Binbin; Luo, Wenhe; Chen, Shili; Nhan, Le Van; Li, Xuguang; Liu, Shutong; Han, Yaning; Liu, Liming; Xing, Baoshan

2015-11-01

Nanoparticles (NPs) are an increasingly common contaminant in agro-environments, and their potential effect on genetically modified (GM) crops has been largely unexplored. GM crop exposure to NPs is likely to increase as both technologies develop. To better understand the implications of nanoparticles on GM plants in agriculture, we performed a glasshouse study to quantify the uptake of Fe2O3 NPs on transgenic and non-transgenic rice plants. We measured nutrient concentrations, biomass, enzyme activity, and the concentration of two phytohormones, abscisic acid (ABA) and indole-3-acetic acid (IAA), and malondialdehyde (MDA). Root phytohormone inhibition was positively correlated with Fe2O3 NP concentrations, indicating that Fe2O3 had a significant influence on the production of these hormones. The activities of antioxidant enzymes were significantly higher as a factor of low Fe2O3 NP treatment concentration and significantly lower at high NP concentrations, but only among transgenic plants. There was also a positive correlation between the treatment concentration of Fe2O3 and iron accumulation, and the magnitude of this effect was greatest among non-transgenic plants. The differences in root phytohormone production and antioxidant enzyme activity between transgenic and non-transgenic rice plants in vivo suggests that GM crops may react to NP exposure differently than conventional crops. It is the first study of NPs that may have an impact on GM crops, and a realistic significance for food security and food safety.

Using thermodynamics to assess biotic and abiotic impediments to root water uptake

NASA Astrophysics Data System (ADS)

Bechmann, Marcel; Hildebrandt, Anke; Kleidon, Axel

2016-04-01

Root water uptake has been the subject of extensive research, dealing with understanding the processes limiting transpiration and understanding strategies of plants to avoid water stress. Many of those studies use models of water flow from the soil through the plant into the atmosphere to learn about biotic and abiotic factors affecting plant water relations. One important question in this context is to identify those processes that are most limiting to water transport, and specifically whether these processes lie within the plant or the soil? Here, we propose to use a thermodynamic formulation of root water uptake to answer this question. The method allows us to separate the energy exported at the root collar into a sum of energy fluxes related to all processes along the flow path, notably including the effect of increasing water retention in drier soils. Evaluation of the several contributions allows us to identify and rank the processes by how much these impede water flow from the soil to the atmosphere. The application of this approach to a complex 3-dimensional root water uptake model reveals insights on the role of root versus soil resistances to limit water flow. We investigate the efficiency of root water uptake in an ensemble of root systems with varying root hydraulic properties. While root morphology is kept the same, root radial and axial resistances are artificially varied. Starting with entirely young systems (uptake roots, high radial, low axial conductance) we increasingly add older roots (transport roots, high axial, low radial conductance) to improve transport within root systems. This yields a range of root hydraulic architectures, where the extremes are limited either by radial uptake capacity or low capacity to transport water along the root system. We model root water uptake in this range of root systems with a 3-dimensional root water uptake model in two different soils, applying constant flux boundary conditions in a dry down experiment and evaluate energy fluxes afterwards. The results show that a minimum of energy is exported in mixed root systems, but a wide range of root systems act near the optimum. A great loss of efficiency only occurs in the extreme cases (only young or only old roots). In all systems near the optimum root water uptake is impeded equally by abiotic and biotic factors in moist conditions, whereas abiotic factors become the limiting factor in dry conditions. The abiotic factors depend on the soil type and are either due to the water retention function or water flow towards individual roots. Small changes in the distribution of root resistance shift the impediments from radial to axial flow path within the root, but without much affecting overall energy export. This suggests that abiotic factors are a dominant control for efficient root water uptake, while morphology only has a comparatively smaller effect, as long as the root system contains a minimum mixture of uptake and transport roots.

Root-Derived Short-Chain Suberin Diacids from Rice and Rape Seed in a Paddy Soil under Rice Cultivar Treatments

PubMed Central

Ji, Haishi; Ding, Yuanjun; Liu, Xiaoyu; Li, Lianqing; Zhang, Dengxiao; Li, Zichuan; Sun, Jingling; Lashari, Muhammad Siddique; Joseph, Stephen; Meng, Yuanduo; Kuzyakov, Yakov; Pan, Genxing

2015-01-01

Suberin-derived substituted fatty acids have been shown to be potential biomarkers for plant-derived carbon (C) in soils across ecosystems. Analyzing root derived suberin compounds bound in soil could help to understand the root input into a soil organic carbon pool. In this study, bound lipids were extracted and identified in root and topsoil samples. Short-chain suberin diacids were quantified under rice (Oryza sativa L.) and rape (Brassica campestris) rotations with different cultivar combinations in a Chinese rice paddy. After removal of free lipids with sequential extraction, the residual bound lipids were obtained with saponification and derivatization before analysis using gas chromatography–mass spectrometry (GC-MS). Diacids C16 and C18 in bound lipids were detected both in rice and rape root samples, while diacids C20 and C22 were detected only in rape root samples. Accordingly, diacids were quantified in both rhizosphere and bulk soil (0–15 cm). The amount of total root-derived diacids in bulk soil varied in a range of 5.6–9.6 mg/kg across growth stages and crop seasons. After one year-round rice-rape rotation, root-derived suberin diacids were maintained at a level of 7–9 mg/kg in bulk soil; this was higher under a super rice cultivar LY than under a hybrid cultivar IIY. While concentrations of the analyzed diacids were generally higher in rhizosphere than in bulk soil, the total diacid (DA) concentration was higher at the time of rape harvest than at rice harvest, suggesting that rape roots made a major contribution to the preservation of diacids in the paddy. Moreover, the net change in the concentration and the ratios of C16:0 DA to C18:1 DA, and of C16:0 DA to C18:0 DA, over a whole growing season, were greater under LY than under IIY, though there was no difference between cultivars within a single growth stage. Overall, total concentration of root-derived suberin diacids was found to be positively correlated to soil organic carbon concentration both for bulk soil and rhizosphere. However, the turnover and preservation of the root suberin biomolecules with soil property and field conditions deserve further field studies. PMID:25961557

Root-Derived Short-Chain Suberin Diacids from Rice and Rape Seed in a Paddy Soil under Rice Cultivar Treatments.

PubMed

Ji, Haishi; Ding, Yuanjun; Liu, Xiaoyu; Li, Lianqing; Zhang, Dengxiao; Li, Zichuan; Sun, Jingling; Lashari, Muhammad Siddique; Joseph, Stephen; Meng, Yuanduo; Kuzyakov, Yakov; Pan, Genxing

2015-01-01

Suberin-derived substituted fatty acids have been shown to be potential biomarkers for plant-derived carbon (C) in soils across ecosystems. Analyzing root derived suberin compounds bound in soil could help to understand the root input into a soil organic carbon pool. In this study, bound lipids were extracted and identified in root and topsoil samples. Short-chain suberin diacids were quantified under rice (Oryza sativa L.) and rape (Brassica campestris) rotations with different cultivar combinations in a Chinese rice paddy. After removal of free lipids with sequential extraction, the residual bound lipids were obtained with saponification and derivatization before analysis using gas chromatography-mass spectrometry (GC-MS). Diacids C16 and C18 in bound lipids were detected both in rice and rape root samples, while diacids C20 and C22 were detected only in rape root samples. Accordingly, diacids were quantified in both rhizosphere and bulk soil (0-15 cm). The amount of total root-derived diacids in bulk soil varied in a range of 5.6-9.6 mg/kg across growth stages and crop seasons. After one year-round rice-rape rotation, root-derived suberin diacids were maintained at a level of 7-9 mg/kg in bulk soil; this was higher under a super rice cultivar LY than under a hybrid cultivar IIY. While concentrations of the analyzed diacids were generally higher in rhizosphere than in bulk soil, the total diacid (DA) concentration was higher at the time of rape harvest than at rice harvest, suggesting that rape roots made a major contribution to the preservation of diacids in the paddy. Moreover, the net change in the concentration and the ratios of C16:0 DA to C18:1 DA, and of C16:0 DA to C18:0 DA, over a whole growing season, were greater under LY than under IIY, though there was no difference between cultivars within a single growth stage. Overall, total concentration of root-derived suberin diacids was found to be positively correlated to soil organic carbon concentration both for bulk soil and rhizosphere. However, the turnover and preservation of the root suberin biomolecules with soil property and field conditions deserve further field studies.

Cadmium uptake by cocoa trees in agroforestry and monoculture systems under conventional and organic management.

PubMed

Gramlich, A; Tandy, S; Andres, C; Chincheros Paniagua, J; Armengot, L; Schneider, M; Schulin, R

2017-02-15

Cadmium (Cd) uptake by cocoa has recently attracted attention, after the European Union (EU) decided to establish values for tolerable Cd concentrations in cocoa products. Bean Cd concentrations from some cocoa provenances, especially from Latin America, were found to exceed these values. Cadmium uptake by cocoa is expected not only to depend on a variety of soil factors, but also on plant and management factors. In this study, we investigated the influence of different production systems on Cd uptake by cocoa in a long-term field trial in the Alto Beni Region of Bolivia, where cocoa trees are grown in monocultures and in agroforestry systems, both under organic and conventional management. Leaf, fruits and roots of two cultivars were sampled from each production system along with soil samples collected around these trees. Leaf, pod husk and bean samples were analysed for Cd, iron (Fe) and zinc (Zn), the roots for mycorrhizal abundance and the soil samples for 'total' and 'available' Cd, Fe and Zn as well as DGT-available Cd and Zn, pH, organic matter, texture, 'available' phosphorus (P) and potassium (K). Only a small part of the variance in bean and pod husk Cd was explained by management, soil and plant factors. Furthermore, the production systems and cultivars alone had no significant influence on leaf Cd. However, we found lower Cd leaf contents in agroforestry systems than in monocultures when analysed in combination with DGT-available soil Cd, cocoa cultivar and soil organic matter. Overall, this model explained 60% of the variance of the leaf Cd concentrations. We explain lower leaf Cd concentrations in agroforestry systems by competition for Cd uptake with other plants. The cultivar effect may be explained by cultivar specific uptake capacities or by a growth effect translating into different uptake rates, as the cultivars were of different size. Copyright © 2016 Elsevier B.V. All rights reserved.

Alteration of cell-wall porosity is involved in osmotic stress-induced enhancement of aluminium resistance in common bean (Phaseolus vulgaris L.)

PubMed Central

Yang, Zhong-Bao; Eticha, Dejene; Rao, Idupulapati Madhusudana; Horst, Walter Johannes

2010-01-01

Aluminium (Al) toxicity and drought are the two major abiotic stress factors limiting common bean production in the tropics. Using hydroponics, the short-term effects of combined Al toxicity and drought stress on root growth and Al uptake into the root apex were investigated. In the presence of Al stress, PEG 6000 (polyethylene glycol)-induced osmotic (drought) stress led to the amelioration of Al-induced inhibition of root elongation in the Al-sensitive genotype VAX 1. PEG 6000 (>> PEG 1000) treatment greatly decreased Al accumulation in the 1 cm root apices even when the roots were physically separated from the PEG solution using dialysis membrane tubes. Upon removal of PEG from the treatment solution, the root tips recovered from osmotic stress and the Al accumulation capacity was quickly restored. The PEG-induced reduction of Al accumulation was not due to a lower phytotoxic Al concentration in the treatment solution, reduced negativity of the root apoplast, or to enhanced citrate exudation. Also cell-wall (CW) material isolated from PEG-treated roots showed a low Al-binding capacity which, however, was restored after destroying the physical structure of the CW. The comparison of the Al3+, La3+, Sr2+, and Rb+ binding capacity of the intact root tips and the isolated CW revealed the specificity of the PEG 6000 effect for Al. This could be due to the higher hydrated ionic radius of Al3+ compared with other cations (Al3+ >> La3+ > Sr2+ > Rb+). In conclusion, the results provide circumstantial evidence that the osmotic stress-inhibited Al accumulation in root apices and thus reduced Al-induced inhibition of root elongation in the Al-sensitive genotype VAX 1 is related to the alteration of CW porosity resulting from PEG 6000-induced dehydration of the root apoplast. PMID:20511277

Heavy metal tolerance and accumulation of Triarrhena sacchariflora, a large amphibious ornamental grass.

PubMed

Tian, R N; Yu, S; Wang, S G; Zhang, Y; Tang, J Y; Liu, Y L; Nie, Y H

2013-01-01

In this study, we report the tolerance and accumulation of Triarrhena sacchariflora to copper (Cu) and cadmium (Cd). The results show that T. sacchariflora had strong tolerance to Cu and Cd stress. The tolerance indexes (TI) were greater than 0.5 for all treatments. The bioconcentration factors (BCFs) to Cu and Cd were both above 1.0. The accumulation ability of roots was stronger than that of shoots, and ranges of BCF to Cu and Cd in roots were 37.89-79.08 and 83.96-300.57, respectively. However, the translocation ability to Cu and Cd was weak, with more than 86% of Cu or Cd accumulated in roots, suggesting an exclusion strategy for heavy metal tolerance. The uptake efficiency (UE) and translocation efficiency (TE) to Cu and Cd increased linearly as the Cu and Cd concentration in the substrate increased. UE was higher than TE, with a maximum of 2,118.90 μg g(-1) root dry weight (DW) (50 mg L(-1) Cu) and 1,847.51 μg g(-1) root DW (20 mg L(-1)Cd), respectively. The results indicate that T. sacchariflora is a Cu- and Cd-tolerant non-hyperaccumulator plant, suggesting that T. sacchariflora could play an important role in phytoremediation in areas contaminated with Cu and Cd.

Cerium enhances germination and shoot growth, and alters mineral nutrient concentration in rice

PubMed Central

García-Morales, Soledad; Pérez-Sato, Juan Antonio

2018-01-01

Cerium (Ce) belongs to the rare earth elements (REEs), and although it is not essential for plants, it can stimulate growth and other physiological processes. The objective of this research was to evaluate the effect of Ce on seed germination, initial seedling growth, and vegetative growth in rice (Oryza sativa L.) cv. Morelos A-98. During the germination process, the seeds were treated with Ce concentrations of 0, 4, 8, and 12 μM; after 5 d, germination percentage was recorded and after 10 d seedling growth was measured. For vegetative growth, a hydroponic system was established where 14-d-old plants without previous Ce treatment were transferred into nutrient solution. After two weeks of acclimatizing, 0, 25, 50, and 100 μM Ce were added to the nutrient solution for 28 d. Ce significantly increased germination and the initial growth variables of the seedlings. During vegetative growth, Ce increased plant height, number of tillers, root volume, and shoot fresh and dry biomass, without affecting root biomass weight. With low Ce concentrations (25 and 50 μM), the concentrations of chlorophylls and amino acids in the shoots were similar to those in the control, like amino acid concentration in the roots at a concentration of 25 μM Ce. Conversely, the concentration of total sugars increased in the shoot with the application of 25, 50, and 100 μM Ce, and in the roots with the application of 50 μM Ce. Also, Ce did not affect the concentration of macro or micronutrients in the shoots. However, in the roots, the high Ce concentration decreased the concentrations of Ca, Fe, Mn, and Zn, while the Mg concentration increased. Our results indicate that Ce, at the right concentrations, can function as a biostimulant in rice germination and growth. PMID:29579100

Hormonal changes in relation to biomass partitioning and shoot growth impairment in salinized tomato (Solanum lycopersicum L.) plants.

PubMed

Albacete, Alfonso; Ghanem, Michel Edmond; Martínez-Andújar, Cristina; Acosta, Manuel; Sánchez-Bravo, José; Martínez, Vicente; Lutts, Stanley; Dodd, Ian C; Pérez-Alfocea, Francisco

2008-01-01

Following exposure to salinity, the root/shoot ratio is increased (an important adaptive response) due to the rapid inhibition of shoot growth (which limits plant productivity) while root growth is maintained. Both processes may be regulated by changes in plant hormone concentrations. Tomato plants (Solanum lycopersicum L. cv Moneymaker) were cultivated hydroponically for 3 weeks under high salinity (100 mM NaCl) and five major plant hormones (abscisic acid, ABA; the cytokinins zeatin, Z, and zeatin-riboside, ZR; the auxin indole-3-acetic acid, IAA; and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid, ACC) were determined weekly in roots, xylem sap, and leaves. Salinity reduced shoot biomass by 50-60% and photosynthetic area by 20-25% both by decreasing leaf expansion and delaying leaf appearance, while root growth was less affected, thus increasing the root/shoot ratio. ABA and ACC concentrations strongly increased in roots, xylem sap, and leaves after 1 d (ABA) and 15 d (ACC) of salinization. By contrast, cytokinins and IAA were differentially affected in roots and shoots. Salinity dramatically decreased the Z+ZR content of the plant, and induced the conversion of ZR into Z, especially in the roots, which accounted for the relative increase of cytokinins in the roots compared to the leaf. IAA concentration was also strongly decreased in the leaves while it accumulated in the roots. Decreased cytokinin content and its transport from the root to the shoot were probably induced by the basipetal transport of auxin from the shoot to the root. The auxin/cytokinin ratio in the leaves and roots may explain both the salinity-induced decrease in shoot vigour (leaf growth and leaf number) and the shift in biomass allocation to the roots, in agreement with changes in the activity of the sink-related enzyme cell wall invertase.

OsWRKY74, a WRKY transcription factor, modulates tolerance to phosphate starvation in rice.

PubMed

Dai, Xiaoyan; Wang, Yuanyuan; Zhang, Wen-Hao

2016-02-01

The WRKY transcription factor family has 109 members in the rice genome, and has been reported to be involved in the regulation of biotic and abiotic stress in plants. Here, we demonstrated that a rice OsWRKY74 belonging to group III of the WRKY transcription factor family was involved in tolerance to phosphate (Pi) starvation. OsWRKY74 was localized in the nucleus and mainly expressed in roots and leaves. Overexpression of OsWRKY74 significantly enhanced tolerance to Pi starvation, whereas transgenic lines with down-regulation of OsWRKY74 were sensitive to Pi starvation. Root and shoot biomass, and phosphorus (P) concentration in rice OsWRKY74-overexpressing plants were ~16% higher than those of wild-type (WT) plants in Pi-deficient hydroponic solution. In soil pot experiments, >24% increases in tiller number, grain weight and P concentration were observed in rice OsWRKY74-overexpressing plants compared to WT plants when grown in P-deficient medium. Furthermore, Pi starvation-induced changes in root system architecture were more profound in OsWRKY74-overexpressing plants than in WT plants. Expression patterns of a number of Pi-responsive genes were altered in the OsWRKY74-overexpressing and RNA interference lines. In addition, OsWRKY74 may also be involved in the response to deficiencies in iron (Fe) and nitrogen (N) as well as cold stress in rice. In Pi-deficient conditions, OsWRKY74-overexpressing plants exhibited greater accumulation of Fe and up-regulation of the cold-responsive genes than WT plants. These findings highlight the role of OsWRKY74 in modulation of Pi homeostasis and potential crosstalk between P starvation and Fe starvation, and cold stress in rice. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Uptake of Germanium and Rare Earth Elements (La, Gd, Er, Nd) by white mustard (Brassica alba L.) and common millet (Panicum milliaceum L.) as affected by Phosphorus Nutrition

NASA Astrophysics Data System (ADS)

Zill, Juliane; Wiche, Oliver

2015-04-01

The effect of phosphate nutrition is important due to the future usage of fertilizer treatment in phytomining experiments e.g. in accumulation of the economically important rare earth elements (REE). It is expected that the trivalent charge of REE will result in complexation with phosphate and REEs could be immobilized and not further bioavailable for plants which would cause losses of REE concentration in biomass. To investigate this influence on lanthanum, neodymium, gadolinium and erbium two plant species Brassica alba (white mustard) and Panicum miliaceum (common millet) were cultured in a greenhouse study. The plants were cultivated onto two different substrates and were poured with modified REE and phosphate solutions within an eight-week period. The concentrations of REE in soil, soil solution and plant samples were determined by inductively coupled plasma-mass spectrometry (ICP-MS). The results show an increase of concentration of REE with increasing levels of element solution applied for both species. REE accumulations are elevated in roots and decrease in the order of roots> leaves> stem> fruit/blossom. Brassica accumulated more REE in root whereas Panicum showed higher REE concentrations in leaves. Exposure to increased phosphate addition did not significantly change the concentrations of REE in both plant species yet the REE concentrations in leaves slightly decreased with increasing phosphate addition. For root and stem no precise trend could be determined. It is most likely that REEs precipitate with phosphate on root surfaces and in the roots. The bioavailability of REE to plants is affected by complexation processes of REEs with phosphate in the rhizosphere. The results indicate that phosphate application plays an important role on REE uptake by roots and accumulation in different parts of a plant and it might have an influence on translocation of REE within the plant.

Stress differentially impacts reserve pools and root exudation: implications for ecosystem functioning and carbon balance

NASA Astrophysics Data System (ADS)

Landhäusser, Simon; Karst, Justine; Wiley, Erin; Gaster, Jacob

2016-04-01

Environmental stress can influence carbon assimilation and the accumulation and distribution of carbon between growth, reserves, and exudation; however, it is unclear how these processes vary by different stress types. Partitioning of carbon to growth and reserves in plants might also vary between different organs. Roots reserves are of particular interest as they link the plant with the soil carbon cycle through exudation. Simple models of diffusion across concentration gradients predict the more C reserves in roots, the more C should be exuded from roots. However, the mechanisms underlying the accumulation and loss of C from roots may differ depending on the stress experienced by the plants. In a controlled study we tested whether different types of stresses (shade, cold soil, and drought) have differential effects on the distribution, abundance, and form (sugar vs. starch) of carbohydrates in seedlings, and whether these changes alone could explain differences in root exudation between stress types. Non-structural carbohydrate (NSC) concentration and pool sizes varied by stress type and between organs. Mass-specific C exudation increased with fine root sugar concentration; however, stress type affected exudation independently of reserve concentration. Seedlings exposed to cold soils exuded the most C on a per root mass basis followed by shade and drought. Through 13C labeling, we also found that depending on the stress type, aspen seedlings may be less able to control the loss of C to the soil compared with unstressed seedlings, resulting in more C leaked to the rhizosphere. The loss of C beyond that predicted by simple concentration gradients might have important implications for ecosystem functioning and carbon balance. If stressed plants lose proportionally more carbon to the soil, existing interactions between plants and soils may decouple under stress, and may include unexpected C fluxes between trees, soils and the atmosphere with a changing climate.

Can acid volatile sulfides (AVS) influence metal concentrations in the macrophyte Myriophyllum aquaticum?

PubMed

Teuchies, Johannes; De Jonge, Maarten; Meire, Patrick; Blust, Ronny; Bervoets, Lieven

2012-08-21

The difference between the molar concentrations of simultaneously extracted metals (SEM) and acid volatile sulfides (AVS) is widely used to predict metal availability toward invertebrates in hypoxic sediments. However, this model is poorly investigated for macrophytes. The present study evaluates metal accumulation in roots and stems of the macrophyte Myriophyllum aquaticum during a 54 day lab experiment. The macrophytes, rooting in metal contaminated, hypoxic, and sulfide rich field sediments were exposed to surface water with 40% or 90% oxygen. High oxygen concentrations in the 90% treatment resulted in dissolution of the metal-sulfide complexes and a gradual increase in labile metal concentrations during the experiment. However, the general trend of increasing availability in the sediment with time was not translated in rising M. aquaticum metal concentrations. Processes at the root-sediment interface, e.g., radial oxygen loss (ROL) or the release of organic compounds by plant roots and their effect on metal availability in the rhizosphere may be of larger importance for metal accumulation than the bulk metal mobility predicted by the SEM-AVS model.

The root application of a purified leonardite humic acid modifies the transcriptional regulation of the main physiological root responses to Fe deficiency in Fe-sufficient cucumber plants.

PubMed

Aguirre, Elena; Elena, Aguirre; Leménager, Diane; Diane, Leménager; Bacaicoa, Eva; Eva, Bacaicoa; Fuentes, Marta; Marta, Fuentes; Baigorri, Roberto; Roberto, Baigorri; Zamarreño, Angel Ma; García-Mina, José Ma

2009-03-01

The aim of this study is to investigate the effect of a well-characterized purified humic acid (non-measurable concentrations of the main plant hormones were detected) on the transcriptional regulation of the principal molecular agents involved in iron assimilation. To this end, non-deficient cucumber plants were treated with different concentrations of a purified humic acid (PHA) (2, 5, 100 and 250 mg of organic carbonL(-1)) and harvested 4, 24, 48, 76 and 92 h from the onset of the treatment. At harvest times, the mRNA transcript accumulation of CsFRO1 encoding for Fe(III) chelate-reductase (EC 1.16.1.7); CsHa1 and CsHa2 encoding for plasma membrane H+-ATPase (EC 3.6.3.6); and CsIRT1 encoding for Fe(II) high-affinity transporter, was quantified by real-time RT-PCR. Meanwhile, the respective enzyme activity of the Fe(III) chelate-reductase and plasma membrane H+-ATPase was also investigated. The results obtained indicated that PHA root treatments affected the regulation of the expression of the studied genes, but this effect was transient and differed (up-regulation or down-regulation) depending on the genes studied. Thus, principally the higher doses of PHA caused a transient increase in the expression of the CsHa2 isoform for 24 and 48 h whereas the CsHa1 isoform was unaffected or down-regulated. These effects were accompanied by an increase in the plasma membrane H+-ATPase activity for 4, 48 and 96 h. Likewise, PHA root treatments (principally the higher doses) up-regulated CsFRO1 and CsIRT1 expression for 48 and 72 h; whereas these genes were down-regulated by PHA for 96 h. These effects were associated with an increase in the Fe(III) chelate-reductase activity for 72 h. These effects were not associated with a significant decrease in the Fe root or leaf concentrations, although an eventual effect on the Fe root assimilation pattern cannot be ruled out. These results stress the close relationships between the effects of humic substances on plant development and iron nutrition. However, further studies are needed in order to elucidate if these effects at molecular level are caused by mechanisms involving hormone-like actions and/or nutritional factors.

Xylem transport of root-derived CO2: An alternative flux pathway of substantial importance for understanding the components of ecosystem respiration

NASA Astrophysics Data System (ADS)

Aubrey, D. P.; Teskey, R. O.

2011-12-01

Forest ecosystem respiration releases one of the largest annual CO2 fluxes of the global carbon cycle and is dominated by belowground autotrophic and heterotrophic contributions. A mechanistic understanding of forest respiratory flux pathways is imperative to understanding carbon cycling in forests. We recently demonstrated that, on a daily basis, the amount of CO2 that fluxes upward from tree root systems into stems via the xylem stream rivals the amount of CO2 diffusing from the soil surface. However, our original observations were limited to only four individual eastern cottonwood (Populus deltoides L.) trees over a single week where environmental conditions remained similar. Here, we expand our investigation to an entire growing season using nine trees. We calculated the internal transport of root-derived CO2 as the product of sap flow and dissolved CO2 concentration ([CO2]) in the xylem at the base of the stem and measured soil CO2 efflux using the [CO2] gradient approach. We then compared the magnitude of these two flux pathways throughout the growing season. The internal transport of root-derived CO2 was equivalent to one-third of the total belowground respiration throughout the growing season. This indicates that autotrophic respiration was substantially higher than previously estimated, and also higher than heterotrophic soil respiration. The quantity of internally transported CO2 was influenced by both seasonal and daily environmental factors that influenced sap flow rates. We observed high concentrations of CO2 in xylem sap which ranged from 1% to 20% [CO2] among and within individual trees through time. Our results provide evidence that belowground autotrophic respiration consumes a larger amount-and stem respiration consumes a smaller amount-of carbohydrates than previously realized. The magnitude of the internal pathway for root-derived CO2 flux highlights the inadequacy of using the CO2 efflux from the soil surface to the atmosphere alone to measure root respiration. We suggest the internal transport of root-derived CO2 should be measured concurrently with CO2 efflux to the atmosphere to more fully understand the components of ecosystem respiration.

Correlation of quinone reductase activity and allyl isothiocyanate formation among different genotypes and grades of horseradish roots.

PubMed

Ku, Kang-Mo; Jeffery, Elizabeth H; Juvik, John A; Kushad, Mosbah M

2015-03-25

Horseradish (Armoracia rusticana) is a perennial crop and its ground root tissue is used in condiments because of the pungency of the glucosinolate (GS)-hydrolysis products allyl isothiocyanate (AITC) and phenethyl isothiocyanate (PEITC) derived from sinigrin and gluconasturtiin, respectively. Horseradish roots are sold in three grades: U.S. Fancy, U.S. No. 1, and U.S. No. 2 according to the USDA standards. These grading standards are primarily based on root diameter and length. There is little information on whether root grades vary in their phytochemical content or potential health promoting properties. This study measured GS, GS-hydrolysis products, potential anticancer activity (as quinone reductase inducing activity), total phenolic content, and antioxidant activities from different grades of horseradish accessions. U.S. Fancy showed significantly higher sinigrin and AITC concentrations than U.S. No. 1 ,whereas U.S. No. 1 showed significantly higher concentrations of 1-cyano 2,3-epithiopropane, the epithionitrile hydrolysis product of sinigrin, and significantly higher total phenolic concentrations than U.S. Fancy.

Contribution of the saprobic fungi Trametes versicolor and Trichoderma harzianum and the arbuscular mycorrhizal fungi Glomus deserticola and G. claroideum to arsenic tolerance of Eucalyptus globulus.

PubMed

Arriagada, C; Aranda, E; Sampedro, I; Garcia-Romera, I; Ocampo, J A

2009-12-01

The presence of high concentrations of arsenic (As) decreased the shoot and root dry weight, chlorophyll and P and Mg content of Eucalyptus globulus colonized with the arbuscular mycorrhizal (AM) fungi Glomus deserticola or G. claroideum, but these parameters were higher than in non-AM plants. As increased the percentage of AM length colonization and succinate dehydrogenase (SDH) activity in the root of E. globulus. Trichoderma harzianum, but not Trametes versicolor, increased the shoot and root dry weight, chlorophyll content, the percentage of AM root length colonization and SDH activity of E. globulus in presence of all As concentrations applied to soil when was inoculated together with G. claroideum. AM fungi increased shoot As and P concentration of E. globulus to higher level than the non-AM inoculated controls. The contribution of the AM and saprobe fungi to the translocation of As from root to shoot of E. globulus is discussed.

Enhanced vadose zone nitrogen removal by poplar during dormancy.

PubMed

Ausland, Hayden; Ward, Adam; Licht, Louis; Just, Craig

2015-01-01

A pilot-scale, engineered poplar tree vadose zone system was utilized to determine effluent nitrate (NO3(-)) and ammonium concentrations resulting from intermittent dosing of a synthetic wastewater onto sandy soils at 4.5°C. The synthetic wastewater replicated that of an industrial food processor that irrigates onto sandy soils even during dormancy which can leave groundwater vulnerable to NO3(-) contamination. Data from a 21-day experiment was used to assess various Hydrus model parameterizations that simulated the impact of dormant roots. Bromide tracer data indicated that roots impacted the hydraulic properties of the packed sand by increasing effective dispersion, water content and residence time. The simulated effluent NO3(-) concentration on day 21 was 1.2 mg-N L(-1) in the rooted treatments compared to a measured value of 1.0 ± 0.72 mg-N L(-1). For the non-rooted treatment, the simulated NO3(-) concentration was 4.7 mg-N L(-1) compared to 5.1 ± 3.5 mg-N L(-1) measured on day 21. The model predicted a substantial "root benefit" toward protecting groundwater through increased denitrification in rooted treatments during a 21-day simulation with 8% of dosed nitrogen converted to N2 compared to 3.3% converted in the non-rooted test cells. Simulations at the 90-day timescale provided similar results, indicating increased denitrification in rooted treatments.

[Effects of Chinese onion' s root exudates on cucumber seedlings growth and rhizosphere soil microorganisms].

PubMed

Yang, Yang; Liu, Shou-wei; Pan, Kai; Wu, Feng-zhi

2013-04-01

Taking the Chinese onion cultivars with different allelopathy potentials as the donor and cucumber as the accepter, this paper studied the effects of Chinese onion' s root exudates on the seedlings growth of cucumber and the culturable microbial number and bacterial community structure in the seedlings rhizosphere soil. The root exudates of the Chinese onion cultivars could promote the growth of cucumber seedlings, and the stimulatory effect increased with the increasing concentration of the root exudates. However, at the same concentrations of root exudates, the stimulatory effect had no significant differences between the Chinese onion cultivars with strong and weak allelopathy potential. The root exudates of the Chinese onion cultivars increased the individual numbers of bacteria and actinomyces but decreased those of fungi and Fusarium in rhizosphere soil, being more significant for the Chinese onion cultivar with high allelopathy potential (L-06). The root exudates of the Chinese onion cultivars also increased the bacterial community diversity in rhizosphere soil. The cloning and sequencing results indicated that the differential bacteria bands were affiliated with Actinobacteria, Proteobacteria, and Anaerolineaceae, and Anaerolineaceae only occurred in the rhizosphere soil in the treatment of high allelopathy potential Chinese onion (L-06). It was suggested that high concentration (10 mL per plant) of root exudates from high allelopathy potential Chinese onion (L-06) could benefit the increase of bacterial community diversity in cucumber seedlings rhizosphere soil.

Adaptive root foraging strategies along a boreal-temperate forest gradient.

PubMed

Ostonen, Ivika; Truu, Marika; Helmisaari, Heljä-Sisko; Lukac, Martin; Borken, Werner; Vanguelova, Elena; Godbold, Douglas L; Lõhmus, Krista; Zang, Ulrich; Tedersoo, Leho; Preem, Jens-Konrad; Rosenvald, Katrin; Aosaar, Jürgen; Armolaitis, Kęstutis; Frey, Jane; Kabral, Naima; Kukumägi, Mai; Leppälammi-Kujansuu, Jaana; Lindroos, Antti-Jussi; Merilä, Päivi; Napa, Ülle; Nöjd, Pekka; Parts, Kaarin; Uri, Veiko; Varik, Mats; Truu, Jaak

2017-08-01

The tree root-mycorhizosphere plays a key role in resource uptake, but also in the adaptation of forests to changing environments. The adaptive foraging mechanisms of ectomycorrhizal (EcM) and fine roots of Picea abies, Pinus sylvestris and Betula pendula were evaluated along a gradient from temperate to subarctic boreal forest (38 sites between latitudes 48°N and 69°N) in Europe. Variables describing tree resource uptake structures and processes (absorptive fine root biomass and morphology, nitrogen (N) concentration in absorptive roots, extramatrical mycelium (EMM) biomass, community structure of root-associated EcM fungi, soil and rhizosphere bacteria) were used to analyse relationships between root system functional traits and climate, soil and stand characteristics. Absorptive fine root biomass per stand basal area increased significantly from temperate to boreal forests, coinciding with longer and thinner root tips with higher tissue density, smaller EMM biomass per root length and a shift in soil microbial community structure. The soil carbon (C) : N ratio was found to explain most of the variability in absorptive fine root and EMM biomass, root tissue density, N concentration and rhizosphere bacterial community structure. We suggest a concept of absorptive fine root foraging strategies involving both qualitative and quantitative changes in the root-mycorrhiza-bacteria continuum along climate and soil C : N gradients. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Interaction of root exudates with the mineral soil constituents and their effect on mineral weathering

NASA Astrophysics Data System (ADS)

Mimmo, T.; Terzano, R.; Medici, L.; Lettino, A.; Fiore, S.; Tomasi, N.; Pinton, R.; Cesco, S.

2012-04-01

Plants release significant amounts of high and low molecular weight organic compounds into the rhizosphere. Among these exudates organic acids (e.g. citric acid, malic acid, oxalic acid), phenolic compounds (e.g. flavonoids), amino acids and siderophores of microbial and/or plant origin strongly influence and modify the biogeochemical cycles of several elements, thus causing changes in their availability for plant nutrition. One class of these elements is composed by the trace elements; some of them are essential for plants even if in small concentrations and are considered micronutrients, such as Fe, Zn, Mn. Their solubility and bioavailability can be influenced, among other factors, by the presence in soil solution of low molecular weight root exudates acting as organic complexing agents that can contribute to the mineral weathering and therefore, to their mobilization in the soil solution. The mobilized elements, in function of the element and of its concentration, can be either important nutrients or toxic elements for plants. The objective of this study was to assess the influence of several root exudates (citric acid, malic acid, oxalic acid, genistein, quercetin and siderophores) on the mineralogy of two different soils (an agricultural calcareous soil and an acidic polluted soil) and to evaluate possible synergic or competitive behaviors. X-ray diffraction (XRD) coupled with Electron Probe Micro Analysis (EPMA) was used to identify the crystalline and amorphous phases which were subjected to mineral alteration when exposed to the action of root exudates. Solubilization of trace metals such as Cu, Zn, Ni, Cr, Pb, Cd as well as of major elements such as Si, Al, Fe and Mn was assessed by means of Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Soil microorganisms have proven to decrease mineral weathering by reducing the concentration of active root exudates in solution. Results obtained are an important cornerstone to better understand the biogeochemical processes acting in the rhizosphere which can play an important role in the availability of trace elements (either nutrient or toxic) for plant uptake. Research is supported by MIUR - FIRB "Futuro in ricerca", internal grant of Unibz (TN5031 & TN5046) and the Autonomous Province of Bolzano (Rhizotyr TN5218).

Root iron plaque alleviates cadmium toxicity to rice (Oryza sativa) seedlings.

PubMed

Fu, Youqiang; Yang, Xujian; Shen, Hong

2018-06-18

Iron plaque (IP) on root surface can enhance the tolerance of plants to environmental stresses. However, it remains unclear the impact of Fe 2+ on cadmium (Cd) toxicity to rice (Oryza sativa) seedlings. In this study, the effects of different Fe 2+ and Cd 2+ concentration combinations on rice growth were examined hydroponically. Results indicated that Fe 2+ concentration up to 3.2 mM did not damage rice roots while induced IP formation obviously. Cd 2+ of 10 μM repressed rice growth significantly, while the addition of 0.2 mM Fe 2+ to 10 μM Cd 2+ solution (Cd+Fe) did not damage rice roots, indicating that Fe 2+ could ameliorate Cd toxicity to rice seedlings. Microstructure analysis showed Cd+Fe treatment induced the formation of IP with dense and intricate network structure, Cd adsorption on the root surface was reduced significantly. Cd concentration of rice roots and shoots and Cd translocation from roots to shoots with Fe+Cd treatment were reduced by 34.1%, 36.0% and 20.1%, respectively, in comparison to a single Cd treatment. Noteworthy, the removal of IP resulted in a larger loss of root biomass under Cd treatment. In addition, Cd+Fe treatment increased the activities of root superoxide dismutase and catalase by 105.5% and 177.4%, and decreased H 2 O 2 and O 2 · - accumulation of rice roots by 56.9% and 35.9%, and recovered Cd-triggered electrolyte leakage obviously, when compared with a single Cd treatment. The results from this experiment indicated that the formed dense IP on rice roots decreased Cd absorption and reactive oxygen species accumulation, and Fe 2+ supply alleviated Cd toxicity to rice seedlings. Copyright © 2018 Elsevier Inc. All rights reserved.

Autotoxicity mechanism of Oryza sativa: transcriptome response in rice roots exposed to ferulic acid

PubMed Central

2013-01-01

Background Autotoxicity plays an important role in regulating crop yield and quality. To help characterize the autotoxicity mechanism of rice, we performed a large-scale, transcriptomic analysis of the rice root response to ferulic acid, an autotoxin from rice straw. Results Root growth rate was decreased and reactive oxygen species, calcium content and lipoxygenase activity were increased with increasing ferulic acid concentration in roots. Transcriptome analysis revealed more transcripts responsive to short ferulic-acid exposure (1- and 3-h treatments, 1,204 genes) than long exposure (24 h, 176 genes). Induced genes were involved in cell wall formation, chemical detoxification, secondary metabolism, signal transduction, and abiotic stress response. Genes associated with signaling and biosynthesis for ethylene and jasmonic acid were upregulated with ferulic acid. Ferulic acid upregulated ATP-binding cassette and amino acid/auxin permease transporters as well as genes encoding signaling components such as leucine-rich repeat VIII and receptor-like cytoplasmic kinases VII protein kinases, APETALA2/ethylene response factor, WRKY, MYB and Zinc-finger protein expressed in inflorescence meristem transcription factors. Conclusions The results of a transcriptome analysis suggest the molecular mechanisms of plants in response to FA, including toxicity, detoxicification and signaling machinery. FA may have a significant effect on inhibiting rice root elongation through modulating ET and JA hormone homeostasis. FA-induced gene expression of AAAP transporters may contribute to detoxicification of the autotoxin. Moreover, the WRKY and Myb TFs and LRR-VIII and SD-2b kinases might regulate downstream genes under FA stress but not general allelochemical stress. This comprehensive description of gene expression information could greatly facilitate our understanding of the mechanisms of autotoxicity in plants. PMID:23705659

Evaluation of the assimilation of As by vegetables in contaminated soils submitted to a remediation process

NASA Astrophysics Data System (ADS)

Pérez-Sirvent, Carmen; Martinez Sanchez, Maria Jose; Agudo, Ines; Belen Martinez, Lucia; Bech, Jaume

2016-04-01

A greenhouse trial was carried out to evaluate the assimilation of heavy metals by three types of plants (lettuce, onion and broccoli), different parts of which are destined for human and farm animals consumption (leaves, roots, fruits). The experiments were carried out to check the validity of the use of calcareous materials to recover soils contaminated with heavy metals. The aim of this work was to apply a technology for decontamination to ensure that As do not enter into the trophic chain at risky levels and analyze and to assess the risk pre and post operational of the different treatments proposed. The materials used was a soils to be remediated (mining soils) and the materials used for remediation were lime filler and Construction and Demolition Waste (CDW). The plants were cultivated in greenhouse with several types of soil. Five experiments were used, namely, Tc (contaminated soil), T1 (uncontaminated soil (blank soil)), T2 (50% T1 + 50% Tc), T3 (Tc + (25%) lime residues coming from quarries) and T4 (Tc + (25%) residues coming from demolition and construction activities). The entire project involves twenty experiments which were prepared from soils highly contaminated mixed with two types of calcareous materials. The total As content of the soils samples, rhizosphere and vegetable samples, were measured and the translocation factor (TF), which is defined as the ratio of metal concentration in the leaves or shoots to the roots, and the Bioconcentration factor (BCF), which is defined as the ratio of metal concentration in the roots to that in soil were calculated. The use of CDR is shown to be a suitable way for remediating soils contaminated by metals. The methodology permits a revalorization of CDW.

In situ silicone tube microextraction: a new method for undisturbed sampling of root-exuded thiophenes from marigold (Tagetes erecta L.) in soil.

PubMed

Mohney, Brian K; Matz, Tricia; Lamoreaux, Jessica; Wilcox, David S; Gimsing, Anne Louise; Mayer, Philipp; Weidenhamer, Jeffrey D

2009-11-01

The difficulties of monitoring allelochemical concentrations in soil and their dynamics over time have been a major barrier to testing hypotheses of allelopathic effects. Here, we evaluate three diffusive sampling strategies that employ polydimethylsiloxane (PDMS) sorbents to map the spatial distribution and temporal dynamics of root-exuded thiophenes from the African marigold, Tagetes erecta. Solid phase root zone extraction (SPRE) probes constructed by inserting stainless steel wire into PDMS tubing were used to monitor thiophene concentrations at various depths beneath marigolds growing in PVC pipes. PDMS sheets were used to map the distribution of thiophenes beneath marigolds grown in thin glass boxes. Concentrations of the two major marigold thiophenes measured by these two methods were extremely variable in both space and time. Dissection and analysis of roots indicated that distribution of thiophenes in marigold roots also was quite variable. A third approach used 1 m lengths of PDMS microtubing placed in marigold soil for repeated sampling of soil without disturbance of the roots. The two ends of the tubing remained out of the soil so that solvent could be washed through the tubing to collect samples for HPLC analysis. Unlike the other two methods, initial experiments with this approach show more uniformity of response, and suggest that soil concentrations of marigold thiophenes are affected greatly even by minimal disturbance of the soil. Silicone tube microextraction gave a linear response for alpha-terthienyl when maintained in soils spiked with 0-10 ppm of this thiophene. This method, which is experimentally simple and uses inexpensive materials, should be broadly applicable to the measurement of non-polar root exudates, and thus provides a means to test hypotheses about the role of root exudates in plant-plant and other interactions.

Congener specificity in the accumulation of dioxins and dioxin-like compounds in zucchini plants grown hydroponically.

PubMed

Inui, Hideyuki; Wakai, Taketo; Gion, Keiko; Yamazaki, Kiyoshi; Kim, Yun-Seok; Eun, Heesoo

2011-01-01

Zucchini cultivars Cucurbita pepo subsp. ovifera cv. Patty Green and subsp. pepo cv. Gold Rush were cultivated hydroponically in a nutrient solution supplemented with a mixture of dioxins and dioxin-like compounds. Patty Green and Gold Rush showed low and high accumulation of these compounds in the aerial parts respectively. In both cultivars, the accumulation of each congener negatively depended on its hydrophobicity. This suggests that desorption and solubilization were partly responsible for congener specificity of accumulation, since this was not found in soil experiments. In contrast, no clear difference in accumulation in the roots was observed between the cultivars, whereas the translocation factors, which are indicators of efficient translocation from the roots to the aerial parts, differed among the congeners hydrophobicity-dependently. There were positive correlations between accumulation in the roots and the hydrophobicity of the polychlorinated biphenyl congeners in both cultivars. These results indicate that translocation was also partly responsible for the congener specificity and accumulation concentrations.

How Roots Perceive and Respond to Gravity.

ERIC Educational Resources Information Center

Moore, Randy

1984-01-01

Discusses graviperception and gravitropism by plant roots. Indicates that graviperception occurs via sedimentation of amyloplasts in columella cells of the root cap and that the minimal graviresponsiveness of lateral roots may be due to the intensity of their caps to establish a concentration gradient of inhibitor(s) sufficient to affect…

Effects of stress concentration on the fatigue strength of 7003-T5 aluminum alloy butt joints with weld reinforcement

NASA Astrophysics Data System (ADS)

Zhu, Zongtao; Li, Yuanxing; Zhang, Mingyue; Hui, Chen

2015-03-01

7003-T5 Aluminum (Al) alloy plates with a thickness of 5 mm are welded by gas metal arc welding (GMAW) method in this work. In order to investigate the influence of stress concentration introduced by weld reinforcement on fatigue strength, the stress concentration factor of the butt joint is calculated. Microscopic and X-ray techniques were utilized to make sure there are no weld defects with large size in butt weld, which can induce extra stress concentration. The cyclic stress - number of cycles to failure (S-N) curves of the joints with and without the welder were obtained by fatigue testing, and the results show that the fatigue strength of 7003-T5 Al alloy butt joints with the weld reinforcement is 50 MPa, which is only 45% of the joints without the weld reinforcement. Fracture surface observation indicated that the fatigue source and propagation are dissimilar for the specimens with and without the welder due to the stress concentration at the weld root. The stress concentration with a factor of 1.7 has great effect on the fatigue strength, but little influence on the tensile strength.

Piriformospora indica Stimulates Root Metabolism of Arabidopsis thaliana.

PubMed

Strehmel, Nadine; Mönchgesang, Susann; Herklotz, Siska; Krüger, Sylvia; Ziegler, Jörg; Scheel, Dierk

2016-07-08

Piriformospora indica is a root-colonizing fungus, which interacts with a variety of plants including Arabidopsis thaliana. This interaction has been considered as mutualistic leading to growth promotion of the host. So far, only indolic glucosinolates and phytohormones have been identified as key players. In a comprehensive non-targeted metabolite profiling study, we analyzed Arabidopsis thaliana's roots, root exudates, and leaves of inoculated and non-inoculated plants by ultra performance liquid chromatography/electrospray ionization quadrupole-time-of-flight mass spectrometry (UPLC/(ESI)-QTOFMS) and gas chromatography/electron ionization quadrupole mass spectrometry (GC/EI-QMS), and identified further biomarkers. Among them, the concentration of nucleosides, dipeptides, oligolignols, and glucosinolate degradation products was affected in the exudates. In the root profiles, nearly all metabolite levels increased upon co-cultivation, like carbohydrates, organic acids, amino acids, glucosinolates, oligolignols, and flavonoids. In the leaf profiles, we detected by far less significant changes. We only observed an increased concentration of organic acids, carbohydrates, ascorbate, glucosinolates and hydroxycinnamic acids, and a decreased concentration of nitrogen-rich amino acids in inoculated plants. These findings contribute to the understanding of symbiotic interactions between plant roots and fungi of the order of Sebacinales and are a valid source for follow-up mechanistic studies, because these symbioses are particular and clearly different from interactions of roots with mycorrhizal fungi or dark septate endophytes.

Medicago sativa--Sinorhizobium meliloti Symbiosis Promotes the Bioaccumulation of Zinc in Nodulated Roots.

PubMed

Zribi, Kais; Nouairi, Issam; Slama, Ines; Talbi-Zribi, Ons; Mhadhbi, Haythem

2015-01-01

In this study we investigated effects of Zn supply on germination, growth, inorganic solutes (Zn, Ca, Fe, and Mg) partitioning and nodulation of Medicago sativa This plant was cultivated with and without Zn (2 mM). Treatments were plants without (control) and with Zn tolerant strain (S532), Zn intolerant strain (S112) and 2 mM urea nitrogen fertilisation. Results showed that M. sativa germinates at rates of 50% at 2 mM Zn. For plants given nitrogen fertilisation, Zn increased plant biomass production. When grown with symbionts, Zn supply had no effect on nodulation. Moreover, plants with S112 showed a decrease of shoot and roots biomasses. However, in symbiosis with S532, an increase of roots biomass was observed. Plants in symbiosis with S. meliloti accumulated more Zn in their roots than nitrogen fertilised plants. Zn supply results in an increase of Ca concentration in roots of fertilised nitrogen plants. However, under Zn supply, Fe concentration decreased in roots and increased in nodules of plants with S112. Zn supply showed contrasting effects on Mg concentrations for plants with nitrogen fertilisation (increase) and plants with S112 (decrease). The capacity of M. sativa to accumulate Zn in their nodulated roots encouraged its use in phytostabilisation processes.

Plant adaptations to severely phosphorus-impoverished soils.

PubMed

Lambers, Hans; Martinoia, Enrico; Renton, Michael

2015-06-01

Mycorrhizas play a pivotal role in phosphorus (P) acquisition of plant roots, by enhancing the soil volume that can be explored. Non-mycorrhizal plant species typically occur either in relatively fertile soil or on soil with a very low P availability, where there is insufficient P in the soil solution for mycorrhizal hyphae to be effective. Soils with a very low P availability are either old and severely weathered or relatively young with high concentrations of oxides and hydroxides of aluminium and iron that sorb P. In such soils, cluster roots and other specialised roots that release P-mobilising carboxylates are more effective than mycorrhizas. Cluster roots are ephemeral structures that release carboxylates in an exudative burst. The carboxylates mobilise sparingly-available sources of soil P. The relative investment of biomass in cluster roots and the amount of carboxylates that are released during the exudative burst differ between species on severely weathered soils with a low total P concentration and species on young soils with high total P concentrations but low P availability. Taking a modelling approach, we explore how the optimal cluster-root strategy depends on soil characteristics, thus offering insights for plant breeders interested in developing crop plants with optimal cluster-root strategies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Phytoremediation potential of Eichornia crassipes in metal-contaminated coastal water.

PubMed

Agunbiade, Foluso O; Olu-Owolabi, Bamidele I; Adebowale, Kayode O

2009-10-01

The potential of Eichornia crassipes to serve as a phytoremediation plant in the cleaning up of metals from contaminated coastal areas was evaluated in this study. Ten metals, As, Cd, Cu, Cr, Fe, Mn, Ni, Pb, V and Zn were assessed in water and the plant roots and shoots from the coastal area of Ondo State, Nigeria and the values were used to evaluate the enrichment factor (EF) and translocation factor (TF) in the plant. The critical concentrations of the metals were lower than those specified for hyperaccumulators thus classifying the plant as an accumulator but the EF and TF revealed that the plant accumulated toxic metals such as Cr, Cd, Pb and As both at the root and at the shoot in high degree, which indicates that the plant that forms a large biomass on the water surface and is not fed upon by animals can serve as a plant for both phytoextraction and rhizofiltration in phytoremediation technology.

The platelet-activating factor acetylhydrolase gene derived from Trichoderma harzianum induces maize resistance to Curvularia lunata through the jasmonic acid signaling pathway.

PubMed

Yu, Chuanjin; Fan, Lili; Gao, Jinxin; Wang, Meng; Wu, Qiong; Tang, Jun; Li, Yaqian; Chen, Jie

2015-01-01

Platelet-activating factor acetylhydrolase (PAF-AH) derived from Trichoderma harzianum was upregulated by the interaction of T. harzianum with maize roots or the foliar pathogen Curvularia lunata. PAF-AH was associated with chitinase and cellulase expressions, but especially with chitinase, because its activity in the KO40 transformant (PAF-AH disruption transformant) was lower, compared with the wild-type strain T28. The result demonstrated that the colonization of maize roots by T. harzianum induced systemic protection of leaves inoculated with C. lunata. Such protection was associated with the expression of inducible jasmonic acid pathway-related genes. Moreover, the data from liquid chromatography-mass spectrometry confirmed that the concentration of jasmonic acid in maize leaves was associated with the expression level of defense-related genes, suggesting that PAF-AH induced resistance to the foliar pathogen. Our findings showed that PAF-AH had an important function in inducing systemic resistance to maize leaf spot pathogen.

Fine root architecture of nine North American trees

Treesearch

Kurt S. Pregitzer; Jared L. DeForest; Andrew J. Burton; Michael F. Allen; Roger W. Ruess; Ronald L. Hendrick

2002-01-01

The fine roots of trees are concentrated on lateral branches that arise from perennial roots. They are important in the acquisition of water and essential nutrients, and at the ecosystem level, they make a significant contribution to biogeochemical cycling. Fine roots have often been studied according to arbitrary size classes, e.g., all roots less than 1 or 2 mm in...

The effect of EDDS and citrate on the uptake of lead in hydroponically grown Matthiola flavida.

PubMed

Mohtadi, Ahmad; Ghaderian, Seyed Majid; Schat, Henk

2013-10-01

Root and shoot lead concentrations and the impact of chelating agents on these were investigated in two populations of the novel metallophyte Matthiola flavida. Plants were exposed in hydroponics to Pb(NO3)2, supplied alone, or in combination with citric acid, or EDDS. When supplied at concentrations expected to bind about 95% of the Pb in a solution containing 1-μM Pb (1000 μM citrate or 3.1 μM EDDS, respectively), the root and shoot Pb concentrations were dramatically lowered, in comparison with a 1-μM free ionic Pb control exposure. A 1-mM EDDS+1-μM Pb treatment decreased the plants' Pb concentrations further, even to undetectable levels in one population. At 100 μM Pb in a 1-mM EDDS-amended solution the Pb concentration increased strongly in shoots, but barely in roots, in comparison with the 1-μM Pb+1-mM EDDS treatment, without causing toxicity symptoms. Further increments of the Pb concentration in the 1-mM EDDS-amended solution, i.e. to 800 and 990 μM, caused Pb hyperaccumulation, both in roots and in shoots, associated with a complete arrest of root growth and foliar necrosis. M. flavida seemed to be devoid of constitutive mechanisms for uptake of Pb-citrate or Pb-EDDS complexes. Hyperaccumulation of Pb-EDDS occurred only at high exposure levels. Pb-EDDS was toxic, but is much less so than free Pb. Free EDDS did not seem to be toxic at the concentrations tested. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effect of nano-zinc oxide on nitrogenase activity in legumes: an interplay of concentration and exposure time

NASA Astrophysics Data System (ADS)

Kumar, Praveen; Burman, Uday; Santra, P.

2015-07-01

Experiments were carried out to study the effect of zinc oxide nanoparticles (nano-ZnO) on nitrogenase activity in legumes. In the first experiment, nodulated roots of cluster bean, moth bean, green gram and cowpea were dipped in Hoagland solution containing 1.5 and 10 μg mL-1 of nano-ZnO for 24 h. Nitrogenase activity in cluster bean, green gram and cowpea roots increased after dipping in solution containing 1.5 μg mL-1 nano-ZnO, but decreased in roots dipped in solution containing 10 μg mL-1 nano-ZnO. However, in moth bean roots, nitrogenase activity decreased after dipping in solution containing either concentration of nano-ZnO. In the second experiment, nodulated roots of green gram were dipped in Hoagland solution containing 1, 4, 6, 8 and 10 μg mL-1 nano-ZnO for 6-30 h before estimating nitrogenase activity. Results showed that an interactive effect of nano-ZnO concentration and exposure time influenced nitrogenase activity. The possible reasons behind this effect have been discussed. A model [ A = 3.44 + 0.46 t - 0.01 t 2 - 0.002 tc 2 ( R 2 = 0.81)] involving linear and power components was developed to simulate the response of nitrogenase activity in green gram roots to the concentration and exposure time of nano-ZnO.

Water management impacts on arsenic speciation and iron-reducing bacteria in contrasting rice-rhizosphere compartments.

PubMed

Somenahally, Anil C; Hollister, Emily B; Yan, Wengui; Gentry, Terry J; Loeppert, Richard H

2011-10-01

Rice cultivated on arsenic (As) contaminated-soils will accumulate variable grain-As concentrations, as impacted by varietal differences, soil variables, and crop management. A field-scale experiment was conducted to study the impact of intermittent and continuous flooding on As speciation and microbial populations in rice rhizosphere compartments of soils that were either historically amended with As pesticide or unamended with As. Rhizosphere-soil, root-plaque, pore-water and grain As were quantified and speciated, and microbial populations in rhizosphere soil and root-plaque were characterized. Total-As concentrations in rhizosphere and grain were significantly lower in intermittently flooded compared to the continuously flooded plots (86% lower in pore-water, 55% lower in root-plaque and 41% lower in grain samples). iAs(V), iAs(III), and DMAs(V) were the predominant As species detected in rhizosphere-soil and root-plaque, pore-water and grain samples, respectively. Relative proportions of Archaea and iron-reducing bacteria (FeRB) were higher in rhizosphere soil compared to root-plaque. In rhizosphere soil, the relative abundance of FeRB was lower in intermittently flooded compared to continuously flooded plots, but there were no differences between root-plaque samples. This study has demonstrated that reductions in dissolved As concentrations in the rhizosphere and subsequent decreases in grain-As concentration can be attained through water management.

The Garlic Allelochemical Diallyl Disulfide Affects Tomato Root Growth by Influencing Cell Division, Phytohormone Balance and Expansin Gene Expression

PubMed Central

Cheng, Fang; Cheng, Zhihui; Meng, Huanwen; Tang, Xiangwei

2016-01-01

Diallyl disulfide (DADS) is a volatile organosulfur compound derived from garlic (Allium sativum L.), and it is known as an allelochemical responsible for the strong allelopathic potential of garlic. The anticancer properties of DADS have been studied in experimental animals and various types of cancer cells, but to date, little is known about its mode of action as an allelochemical at the cytological level. The current research presents further studies on the effects of DADS on tomato (Solanum lycopersicum L.) seed germination, root growth, mitotic index, and cell size in root meristem, as well as the phytohormone levels and expression profile of auxin biosynthesis genes (FZYs), auxin transport genes (SlPINs), and expansin genes (EXPs) in tomato root. The results showed a biphasic, dose-dependent effect on tomato seed germination and root growth under different DADS concentrations. Lower concentrations (0.01–0.62 mM) of DADS significantly promoted root growth, whereas higher levels (6.20–20.67 mM) showed inhibitory effects. Cytological observations showed that the cell length of root meristem was increased and that the mitotic activity of meristematic cells in seedling root tips was enhanced at lower concentrations of DADS. In contrast, DADS at higher concentrations inhibited root growth by affecting both the length and division activity of meristematic cells. However, the cell width of the root meristem was not affected. Additionally, DADS increased the IAA and ZR contents of seedling roots in a dose-dependent manner. The influence on IAA content may be mediated by the up-regulation of FZYs and PINs. Further investigation into the underlying mechanism revealed that the expression levels of tomato EXPs were significantly affected by DADS. The expression levels of EXPB2 and beta-expansin precursor were increased after 3 d, and those of EXP1, EXPB3 and EXLB1 were increased after 5 d of DADS treatment (0.41 mM). This result suggests that tomato root growth may be regulated by multiple expansin genes at different developmental stages. Therefore, we conclude that the effects of DADS on the root growth of tomato seedlings are likely caused by changes associated with cell division, phytohormones, and the expression levels of expansin genes. PMID:27555862

Glucosinolate profile and distribution among plant tissues and phenological stages of field-grown horseradish.

PubMed

Agneta, Rosa; Lelario, Filomena; De Maria, Susanna; Möllers, Christian; Bufo, Sabino Aurelio; Rivelli, Anna Rita

2014-10-01

Profile and distribution of glucosinolates (GLS) were detected in plant tissues of horseradish at different developmental stages: beginning of vegetative re-growth, flowering and silique formation. The GLS profile varied widely in the different tissues: we identified 17 GLS in roots and sprouts, one of which was not previously characterized in horseradish, i.e. the 2(S)-hydroxy-2-phenylethyl-GLS (glucobarbarin) and/or 2(R)-hydroxy-2-phenylethyl-GLS (epiglucobarbarin), 11 already found in the roots, including the putative 2-methylsulfonyl-oxo-ethyl-GLS, and 5 previously recognized only in the sprouts. Fifteen of those GLS were also identified in young and cauline leaves, 12 in the mature leaves and 13 in the inflorescences. No difference in GLS profile was observed in plant among the phenological stages. Differences in concentrations of GLS, quantified as desulfated, were found in plant. At the beginning of vegetative re-growth, sprouts while showing the same profile of the roots were much richer in GLS having the highest total GLS concentrations (117.5 and 7.7μmolg(-1) dry weight in sprouts and roots, respectively). During flowering and silique forming stages, the roots still maintained lower amount of total GLS (7.4μmolg(-1) of dry weight, on average) with respect to the epigeous tissues, in which mature and young leaves showed the highest total concentrations (70.5 and 73.8μmolg(-1) of dry weight on average, respectively). Regardless of the phenological stages, the aliphatic GLS were always predominant in all tissues (95%) followed by indolic (2.6%) and benzenic (2.4%) GLS. Sinigrin contributed more than 90% of the total GLS concentration. Aliphatic GLS concentrations were much higher in the epigeous tissues, particularly in the mature and young leaves, while benzenic and indolic GLS concentrations were higher in the roots. Through the phenological stages, GLS concentration increased in young and mature leaves and decreased in cauline leaves and inflorescences, while it remained constant over time in roots. Copyright © 2014 Elsevier Ltd. All rights reserved.

Plant-Sediment Interactions in Salt Marshes - An Optode Imaging Study of O2, pH, and CO 2 Gradients in the Rhizosphere.

PubMed

Koop-Jakobsen, Ketil; Mueller, Peter; Meier, Robert J; Liebsch, Gregor; Jensen, Kai

2018-01-01

In many wetland plants, belowground transport of O 2 via aerenchyma tissue and subsequent O 2 loss across root surfaces generates small oxic root zones at depth in the rhizosphere with important consequences for carbon and nutrient cycling. This study demonstrates how roots of the intertidal salt-marsh plant Spartina anglica affect not only O 2 , but also pH and CO 2 dynamics, resulting in distinct gradients of O 2 , pH, and CO 2 in the rhizosphere. A novel planar optode system (VisiSens TD ® , PreSens GmbH) was used for taking high-resolution 2D-images of the O 2 , pH, and CO 2 distribution around roots during alternating light-dark cycles. Belowground sediment oxygenation was detected in the immediate vicinity of the roots, resulting in oxic root zones with a 1.7 mm radius from the root surface. CO 2 accumulated around the roots, reaching a concentration up to threefold higher than the background concentration, and generally affected a larger area within a radius of 12.6 mm from the root surface. This contributed to a lowering of pH by 0.6 units around the roots. The O 2 , pH, and CO 2 distribution was recorded on the same individual roots over diurnal light cycles in order to investigate the interlinkage between sediment oxygenation and CO 2 and pH patterns. In the rhizosphere, oxic root zones showed higher oxygen concentrations during illumination of the aboveground biomass. In darkness, intraspecific differences were observed, where some plants maintained oxic root zones in darkness, while others did not. However, the temporal variation in sediment oxygenation was not reflected in the temporal variations of pH and CO 2 around the roots, which were unaffected by changing light conditions at all times. This demonstrates that plant-mediated sediment oxygenation fueling microbial decomposition and chemical oxidation has limited impact on the dynamics of pH and CO 2 in S. anglica rhizospheres, which may in turn be controlled by other processes such as root respiration and root exudation.

Comparison of MRI techniques and modelling with R-SWMS for determining solute distribution patterns and root water uptake of a white lupine plant (Lupinus Albus L.).

NASA Astrophysics Data System (ADS)

Koch, Axelle; Schröder, Natalie; Pohlmeier, Andreas; Garré, Sarah; Vanderborght, Jan; Javaux, Mathieu

2017-04-01

Measuring water extraction by plant would allow us to better understand root water uptake processes and how soil and plant properties affect them. Yet, direct measurement of root water uptake is still challenging and determining its distribution requires coupling experimentation and modelling. In this study, we investigated how the 3D monitoring of a tracer movement in a sand container with a lupine plant could inform us about root water uptake process. A sand column (10 cm height, 5 cm inner diameter) planted with an 18-day-old white lupine was subject to a tracer experiment with a chemically inert tracer (1 mmol/L Gd-DTPA2-) applied for 6 days. Then the tracer and water fluxes were stopped. The plume was monitored in 3-D for 7 days by Magnetic Resonance Imaging (Haber-Pohlmeier et al, unp). In addition the breakthrough curve at the outlet was also measured. We used a biophysical 3-D soil-plant model: R-SWMS (Javaux et al, 2008) to extract information from this experiment. First, we ran a virtual experiment to check the assumption that Gd concentration increase around roots is proportional to the extracted soil water during the same period. We also investigated whether this type of experiment helps discriminate different root hydraulic properties with a sensitivity analysis. Then, we compared the experimental and simulated Gd concentration patterns. A preliminary (qualitative) assessment showed that measured Gd distribution patterns were better represented by the model at day 7, where the main driver of the concentration distribution was root and not soil heterogeneity (which is not taken into account in the model). The main spatial and temporal features of the transport where adequately reproduced by the model in particular during the last day. The distribution of the tracer was shown to be sensitive to the root hydraulic properties. To conclude, information about root water uptake distributions and so about root hydraulic properties could be deduced from Gd concentration maps. Keywords: R-SWMS; Modelling; MRI; Root Water Uptake; Gadolinium

Effects of feeding fresh cassava root with high-sulfur feed block on feed utilization, rumen fermentation, and blood metabolites in Thai native cattle.

PubMed

Cherdthong, Anusorn; Khonkhaeng, Benjamad; Seankamsorn, Anuthida; Supapong, Chanadol; Wanapat, Metha; Gunun, Nirawan; Gunun, Pongsatron; Chanjula, Pin; Polyorach, Sineenart

2018-03-14

The objective of this research was to evaluate the effect of feeding fresh cassava root (CR) along with a feed block containing high was to sulfur (FBS) on feed intake, digestibility, rumen fermentation, and blood thiocyanate concentration in Thai native beef cattle. Four Thai male native beef cattle, initial body weight (BW) of 130 + 20.0 kg, were used in this study. The experiments were randomly assigned according to a 2 × 2 factorial arrangement in a 4 × 4 Latin square design. The main factors were supplemented fresh CR levels (1.0 and 1.5% BW) and across to a feed block supplemented with sulfur added 2% (FBS-2) and 4% (FBS-4). Intakes of rice straw, concentrate diets, and FBS were not affected by treatments. Intakes of CR, sulfur, and total intake were significantly altered by the FBS treatment. The apparent dry matter and organic matter digestibility coefficient were significantly higher in animals fed FBS-4 than in those fed FBS-2. The ruminal ammonia nitrogen concentration was not affected by treatment and ranged from 15.6 to 17.6 mg/dl. Populations of protozoa and fungal zoospores were similar across treatments, whereas the bacterial population was significantly different between sulfur levels in the feed block. Feeding CR with FBS did not change total volatile fatty acid (VFA) concentrations and VFA profiles except for the propionic acid concentration, which was higher in the group with CR supplementation at 1.5% BW. Cattle fed CR with FBS showed similar blood urea nitrogen concentration at various feeding times and overall. In contrast, CR supplementation at 1.5% BW with FBS-2 increased blood thiocyanate concentrations. Therefore, supplementation of FBS-2 was beneficial to Thai native beef cattle fed with 1.5% BW fresh CR as it improved digestibility and rumen fermentation presumed, because HCN from fresh cassava root was converted into thiocyanate, which is nontoxic to farm animals.

Total reflection X-ray fluorescence spectrometric determination of elements in water hyacinth from the Lerma River

NASA Astrophysics Data System (ADS)

Tejeda, S.; Zarazúa, G.; Ávila-Pérez, P.; Carapia-Morales, L.; Martínez, T.

2010-06-01

The Lerma River is one of the most polluted body water in Mexico. For this reason, only the highly resistant organisms such as water hyacinth are able to reproduce in this river. The aim of this work was to evaluate the concentration of K, S, Fe, Ca, Mn, Ti, Zn, Sr, Rb, Cu, Cr, Ni, Pb and Br in roots of water hyacinth ( Eichhornia crassipes) from the Lerma River. The samples were collected from five sites in the river and analyzed in triplicate using a TXRF Spectrometer 'TX-2000 Ital Structures' with a Si(Li) detector and a resolution of 140 eV (FWHM) at Mn Kα. A Mo tube (40 kV, 30 mA) with 17.4 KeV excitation energy was used for a counting time of 500 s. Results show that the average metal concentration in the water hyacinth roots decrease in the following order: K (9698.2 µg/g) > S (7593.3 µg/g) > Fe (4406.6 µg/g) > Ca (2601.8 µg/g) > Mn (604.2 µg/g) > Ti (230.7 µg/g) > Zn (51.65 µg/g) > Sr (43.55 µg/g) > Rb (18.61 µg/g) > Cu (12.78 µg/g) > Cr (6.45 µg/g) > Ni (4.68 µg/g) > Pb (4.32 µg/g) > Br (4.31 µg/g) and the bioconcentration factors in the water hyacinth decrease in the sequence: Ti > Fe > Mn > Cu > Ni > Zn > S > Pb > Rb > K > Cr > Sr > Br > Ca. The concentrations in roots of water hyacinth reflect the high pollution level of the river.

Root-Associated Methane Oxidation and Methanogenesis: Key Determinants of Wetland Methane Emissions

NASA Technical Reports Server (NTRS)

King, G. M.

1997-01-01

During the award period, we have assessed the extent and controls of methane oxidation in north temperate wetlands. It is evident that wetlands have been a major global source of atmospheric methane in the past, and are so at present. It is also evident that microbial methane oxidation consumes a variable fraction of total wetland methane production, perhaps 10%-90%. Methane oxidation is thus a potentially important control of wetland methane emission. Our efforts have been designed to determine the extent of the process, its controls, and possible relationships to changes that might be expected in wetlands as a consequence of anthropogenic or climate-related disturbances. Current work, has emphasized controls of methane oxidation associated with rooted aquatic plants. As for the sediment-water interface, we have observed that oxygen availability is a primary limiting factor. Our conclusion is based on several different lines of evidence obtained from in vitro and in situ analyses. First, we have measured the kinetics of methane oxidation by intact plant roots harboring methane-oxidizing bacteria, as well as the kinetics of the methanotrophs themselves. Values for the half-saturation constant (apparent K(sub m)) are approximately 5 microns. These values are roughly equivalent to, or much less than porewater methane concentrations, indicating that uptake is likely saturated with respect to methane, and that some other parameter must limit activity. Methane concentrations in the lacunar spaces at the base of plant stems are also comparable to the half-saturation constants (when expressed as equivalent dissolved concentrations), providing further support for limitation of uptake by parameters other than methane.

Time and substrate dependent exudation of carboxylates by Lupinus albus L. and Brassica napus L.

PubMed

Mimmo, Tanja; Hann, Stephan; Jaitz, Leonhard; Cesco, Stefano; Gessa, Carlo Emanuele; Puschenreiter, Markus

2011-11-01

Root exudates influence significantly physical, chemical and biological characteristics of rhizosphere soil. Their qualitative and quantitative composition is affected by environmental factors such as pH, soil type, oxygen status, light intensity, soil temperature, plant growth, nutrient availability and microorganisms. The aim of the present study was to assess the influence of growth substrate and plant age on the release of carboxylates from Lupinus albus L. and Brassica napus L. Both plant species were studied in continuously percolated microcosms filled with either sand, soil or sand + soil (1:1) mixture. Soil solution was collected every week at 7, 14, 21, 28 and 35 days after planting (DAP). Carboxylate concentrations were determined by reversed-phase liquid chromatography - electrospray ionization - time of flight mass spectrometry (LC-ESI-TOFMS). Oxalate, citrate, succinate, malate and maleate were detected in soil solutions of both plant species. Their concentrations were correlated with the physiological status of the plant and the growth substrate. Oxalate was the predominant carboxylate detected within the soil solution of B. napus plants while oxalate and citrate were the predominant ones found in the soil solutions of L. albus plants. The sampling determination of carboxylates released by plant roots with continuous percolation systems seems to be promising as it is a non-destructive method and allows sampling and determination of soluble low molecular weight organic compounds derived from root exudation as well as the concentration of soluble nutrients, which both might reflect the nutritional status of plants. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Appearance of konzo in South-Kivu, a wartorn area in the Democratic Republic of Congo.

PubMed

Chabwine, J N; Masheka, C; Balol'ebwami, Z; Maheshe, B; Balegamire, S; Rutega, B; Wa Lola, M; Mutendela, K; Bonnet, M-J; Shangalume, O; Balegamire, J M; Nemery, B

2011-03-01

Konzo is an upper motor neuron disease characterized by sudden-onset and irreversible spastic paraparesis occurring in nutritionally compromised people. It is associated with consumption of insufficiently processed cyanogenic-toxic cassava. Cassava, the main caloric source in the Democratic Republic of Congo, has been safely consumed for decades in the Eastern Province of South-Kivu. However, in the context of long-lasting war and violent conflicts, cases of spastic paraparesis resembling konzo appeared in a populous area (Burhinyi). Two field surveys (2003 and 2005) identified 41 subjects meeting clinical criteria of konzo and suffering from (chronic) malnutrition. Their urinary thiocyanate concentrations (median 129, range 20-688, SD 146 μg/L), and cyanogen levels (median 20 ppm, range 5-300 ppm, SD 73 ppm) in cassava roots from their household stocks were high. The source of cyanogenic-toxicity was unprocessed fresh cassava roots during harvest period, but probably also insufficiently processed roots. This first report of konzo in South-Kivu concludes that occurrence of konzo was triggered by food shortages because of the longstanding state of insecurity. Contributory factors included the introduction of new varieties of (bitter) cassava, but konzo may actually be caused by a combination of factors that are yet to be understood. Copyright © 2010 Elsevier Ltd. All rights reserved.

Toxicity of arsenic (III) and (V) on plant growth, element uptake, and total amylolytic activity of mesquite (Prosopis juliflora x P. velutina).

PubMed

Mokgalaka-Matlala, Ntebogeng S; Flores-Tavizón, Edith; Castillo-Michel, Hiram; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L

2008-01-01

The effects of arsenite [As(III)] and arsenate [As(V)] on the growth of roots, stems, and leaves and the uptake of arsenic (As), micro- and macronutrients, and total amylolytic activity were investigated to elucidate the phytotoxicity of As to the mesquite plant (Prosopis juliflora x P. velutina). The plant growth was evaluated by measuring the root and shoot length, and the element uptake was determined using inductively coupled plasma optical emission spectroscopy. The root and leaf elongation decreased significantly with increasing As(III) and As(V) concentrations; whereas, stem elongation remained unchanged. The As uptake increased with increasing As(III) or As(V) concentrations in the medium. Plants treated with 50 mg/L As(III) accumulated up to 920 mg/kg dry weight (d wt) in roots and 522 mg/kg d wt in leaves, while plants exposed to 50 mg/L As(V) accumulated 1980 and 210 mg/kg d wt in roots and leaves, respectively. Increasing the As(V) concentration up to 20 mg/L resulted in a decrease in the total amylolytic activity. On the contrary, total amylolytic activity in As(III)-treated plants increased with increasing As concentration up to 20 mg/L. The macro- and micronutrient concentrations changed in As-treated plants. In shoots, Mo and K were reduced but Ca was increased, while in roots Fe and Ca were increased but K was reduced. These changes reduced the size of the plants, mainly in the As(III)-treated plants; however, there were no visible sign of As toxicity.

Effect of fluoride on photosynthesis, growth and accumulation of four widely cultivated rice (Oryza sativa L.) varieties in India.

PubMed

Mondal, Naba Kumar

2017-10-01

Long-term use of fluoride contaminated groundwater to irrigate crops; especially paddy rice (Oryza sativa L.) has resulted in elevated soil fluoride levels in Eastern India. There is, therefore, growing concern regarding accumulation of fluoride in rice grown on these soils. A laboratory experiment was conducted to investigate the effect of F on germination and phytotoxicity of four varieties of rice (Orzya sativa L.) (MTU-1010; IET-4094; IET-4786 and GB-1) grown in petri dish in a green house with inorganic sodium fluoride (NaF). Three different levels (0, 5, 10 and 20mg/L) of NaF solution were applied. At the end of the experiment (28 days), biochemical analysis (pigment, sugar, protein, amino acid and phenol), lipid peroxidation, root ion leakage and catalase activity along with fluoride accumulation and fresh and dry weight of roots and shoots of four cultivars were measured. The results revealed that all the four studied varieties exhibited gradual decrease of germination pattern with increasing concentration of F. Pigment and growth morphological study clearly demonstrated that the variety IET-4094 was the least influenced by F compare to the other three varieties of rice. The translocation factor (TF) was recorded to be the highest for variety IET-4786 (0.215 ± 0.03) at 5mg/L F concentration. All the four varieties showed higher level of fluoride accumulation in root than in shoot. Variable results were recorded for biochemical parameters and lipid peroxidation. Catalase activity and relative conductivity (root ion leakage) gradually increased with increasing F concentration for all the four varieties. It is speculated that fluoride accumulation in rice straw at very high levels will affect the feeding cattle and such contaminated straw could be a direct threat to their health and also, indirectly, to human health via presumably contaminated meat and milk. Copyright © 2017. Published by Elsevier Inc.

BIO-MONITORING FOR URANIUM USING STREAM-SIDE TERRESTRIAL PLANTS AND MACROPHYTES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caldwell, E.; Duff, M.; Hicks, T.

2012-01-12

This study evaluated the abilities of various plant species to act as bio-monitors for environmental uranium (U) contamination. Vegetation and soil samples were collected from a U processing facility. The water-way fed from facility storm and processing effluents was the focal sample site as it represented a primary U transport mechanism. Soils and sediments from areas exposed to contamination possessed U concentrations that averaged 630 mg U kg{sup -1}. Aquatic mosses proved to be exceptional accumulators of U with dry weight (dw) concentrations measuring as high as 12500 mg U kg{sup -1} (approximately 1% of the dw mass was attributablemore » to U). The macrophytes (Phragmites communis, Scripus fontinalis and Sagittaria latifolia) were also effective accumulators of U. In general, plant roots possessed higher concentrations of U than associated upper portions of plants. For terrestrial plants, the roots of Impatiens capensis had the highest observed levels of U accumulation (1030 mg kg{sup -1}), followed by the roots of Cyperus esculentus and Solidago speciosa. The concentration ratio (CR) characterized dry weight (dw) vegetative U levels relative to that in associated dw soil. The plant species that accumulated U at levels in excess of that found in the soil were: P. communis root (CR, 17.4), I. capensis root (CR, 3.1) and S. fontinalis whole plant (CR, 1.4). Seven of the highest ten CR values were found in the roots. Correlations with concentrations of other metals with U were performed, which revealed that U concentrations in the plant were strongly correlated with nickel (Ni) concentrations (correlation: 0.992; r-squared: 0.984). Uranium in plant tissue was also strongly correlated with strontium (Sr) (correlation: 0.948; r-squared: 0.899). Strontium is chemically and physically similar to calcium (Ca) and magnesium (Mg), which were also positively-correlated with U. The correlation with U and these plant nutrient minerals, including iron (Fe), suggests that active uptake mechanisms may influence plant U accumulation.« less

The effect of phosphate bio-fertilizer (Barvar-2) on the growth of marigold.

PubMed

Zaredost, Fatemeh; Hashemabadi, Davood; Ziyabari, Maryam Barari; Torkashvand, Ali Mohammadi; Kaviani, Behzad; Solimandarabi, Maryam Jadid; Zarchini, Mohammad

2014-03-01

The present study was conducted to study the individual and combined effect of bio-fertilizer (Barvar-2) and chemical phosphate fertilizer on the floral quality of marigold (Tagetes erecta L.). A factorial experiment was carried out which consisted of two factors: i) inoculation of seed, root and seed + root with bio-fertilizer (Barvar-2) and control; application of chemical phosphorus at 100 mg I(-1), 200 mg l(-1), 300 mg l(-1) and 400 mg l(-1) levels. In this study, flowering time, display life, fresh and dry weight of flower, available soil phosphorus, shoot phosphorus and carotenoid content were evaluated. Results showed that the combined effect of bio- and chemical fertilizer was insignificant (p < 1 and 5%) for most of the characteristics studied except for shoot phosphorus and carotenoid content in petals. The lowest time to flowering (64.67 days) was obtained in seeds and transplant roots inoculation to bio-fertilizer x 400 mg I(-1) P. Maximum display life (25.35), fresh weight (16.20 g), carotenoid content (3.903 mg g(-1) d. wt.) and concentration of P in shoots (0.352%) were observed in transplant roots inoculation to bio-fertilizer x 400 mg I(-1) P.

Organ-specific defence strategies of pepper (Capsicum annuum L.) during early phase of water deficit.

PubMed

Sziderics, Astrid Heide; Oufir, Mouhssin; Trognitz, Friederike; Kopecky, Dieter; Matusíková, Ildikó; Hausman, Jean-Francois; Wilhelm, Eva

2010-03-01

Drought is one of the major factors that limits crop production and reduces yield. To understand the early response of plants under nearly natural conditions, pepper plants (Capsicum annuum L.) were grown in a greenhouse and stressed by withholding water for 1 week. Plants adapted to the decreasing water content of the soil by adjustment of their osmotic potential in root tissue. As a consequence of drought, strong accumulation of raffinose, glucose, galactinol and proline was detected in the roots. In contrast, in leaves the levels of fructose, sucrose and also galactinol increased. Due to the water deficit cadaverine, putrescine, spermidine and spermine accumulated in leaves, whereas the concentration of polyamines was reduced in roots. To study the molecular basis of these responses, a combined approach of suppression subtractive hybridisation and microarray technique was performed on the same material. A total of 109 unique ESTs were detected as responsive to drought, while additional 286 ESTs were selected from the bulk of rare transcripts on the array. The metabolic profiles of stressed pepper plants are discussed with respect to the transcriptomic changes detected, while attention is given to the differences between defence strategies of roots and leaves.

Project Work on Plant Roots.

ERIC Educational Resources Information Center

Devonald, V. G.

1986-01-01

Methods of investigating plant root growth developed for research purposes can be adopted for student use. Investigations of the effect of water table level and of ethylene concentration are described, and techniques of measuring root growth are explained. (Author/ML)

Elevated CO2 or O3 effects on fine-root survivorship in ponderosa pine

EPA Science Inventory

Atmospheric carbon dioxide (CO2) and ozone (O3) concentrations are rising, which may have opposing effects on tree C balance and allocation to fine roots. More information is needed on interactive CO2 and O3 effects on roots, particularly fine-root life span, a critical demograp...

ELEVATED CO2 AND O3 EFFECTS ON FINE-ROOT SURVIVORSHIP IN PONDEROSA PINE MESOCOSMS

EPA Science Inventory

Atmospheric carbon dioxide (CO2) and ozone (O3) concentrations are rising, which may have opposing effects on tree C balance and allocation to fine roots. More information is needed on interactive CO2 and O3 effects on roots, particularly fine-root life span, a critical demograph...

Comparative effectiveness of metal ions in inducing curvature of primary roots of Zea mays

NASA Technical Reports Server (NTRS)

Hasenstein, K. H.; Evans, M. L.; Stinemetz, C. L.; Moore, R.; Fondren, W. M.; Koon, E. C.; Higby, M. A.; Smucker, A. J.

1988-01-01

We used five cultivars of Zea mays (Bear Hybrid WF9 * 38MS, B73 * Missouri 17, Yellow Dent, Merit, and Great Lakes Hybrid 422) to reinvestigate the specificity of metal ions for inducing root curvature. Of 17 cations tested, 6 (Al3+, Ba2+, Ca2+, Cd2+, Cu2+, Zn2+) induced curvature. Roots curved away from Al3+, Ba2+, and Cd2+. Roots curved away from low (0.1 millimolar) concentrations of Cu2+ but toward higher (1-5 millimolar) concentrations. Roots initially curved away from Zn2+ but the direction of the subsequent curvature was unpredictable. In most cases, roots of all cultivars curved towards calcium. However, in some tests there was no response to calcium or even (especially in the cultivars Merit and B73 * Missouri 17) substantial curvature away from calcium. The results indicate that the induction of root curvature is not specific for calcium. The results are discussed relative to the possible role of calmodulin as a mediator of ion-induced root curvature.

Comparative Effectivness of Metal Ions in Inducing Curvature of Primary Roots of Zea mays1

PubMed Central

Hasenstein, Karl Heinz; Evans, Michael L.; Stinemetz, Charles L.; Moore, Randy; Fondren, W. Mark; Koon, E. Colin; Higby, Mary A.; Smucker, Alvin J. M.

1988-01-01

We used five cultivars of Zea mays (Bear Hybrid WF9 * 38MS, B73 * Missouri 17, Yellow Dent, Merit, and Great Lakes Hybrid 422) to reinvestigate the specificity of metal ions for inducing root curvature. Of 17 cations tested, 6 (Al3+, Ba2+, Ca2+, Cd2+, Cu2+, Zn2+) induced curvature. Roots curved away from Al3+, Ba2+, and Cd2+. Roots curved away from low (0.1 millimolar) concentrations of Cu2+ but toward higher (1-5 millimolar) concentrations. Roots initially curved away from Zn2+ but the direction of the subsequent curvature was unpredictable. In most cases, roots of all cultivars curved towards calcium. However, in some tests there was no response to calcium or even (especially in the cultivars Merit and B73 * Missouri 17) substantial curvature away from calcium. The results indicate that the induction of root curvature is not specific for calcium. The results are discussed relative to the possible role of calmodulin as a mediator of ion-induced root curvature. PMID:11538239

Accumulation of Apoplastic Iron in Plant Roots 1

PubMed Central

Longnecker, Nancy; Welch, Ross M.

1990-01-01

We hypothesized that the resistance of Hawkeye (HA) soybean (Glycine max L.) to iron-deficiency induced chlorosis (IDC) is correlated to an ability to accumulate a large pool of extracellular-root iron which can be mobilized to shoots as the plants become iron deficient. Iron in the root apoplast was assayed after efflux from the roots of intact plants in nutrient solution treated with sodium dithionite added under anaerobic conditions. Young seedlings of HA soybean accumulated a significantly larger amount of extracellular iron in their roots than did either IDC-susceptible PI-54619 (PI) soybean or IDC-resistant IS-8001 (IS) sunflower (Helianthus annus L.). Concurrently, HA soybean had much higher concentrations of iron in their shoots than either PI soybean or IS sunflower. The concentration of iron in the root apoplast and in shoots of HA soybean decreased sharply within days after the first measurements of extracellular root iron were made, in both +Fe and −Fe treatments. The accumulation of short-term iron reserves in the root apoplast and translocation of iron in large quantities to the shoot may be important characteristics of IDC resistance in soybeans. PMID:16667242

Growth and root development of four mangrove seedlings under varying salinity

NASA Astrophysics Data System (ADS)

Basyuni, M.; Keliat, D. A.; Lubis, M. U.; Manalu, N. B.; Syuhada, A.; Wati, R.; Yunasfi

2018-03-01

This present study describes four mangrove seedlings namely Bruguiera cylindrica, B. sexangula, Ceriops tagal, and Rhizophora apiculata in response to salinity with particular emphasis to root development. The seedlings of four mangroves were grown for 5 months in 0%, 0.5%, 1.5%, 2.0% and 3.0% salt concentration. Salinity significantly decreased the growth (diameter and plant height) of all mangrove seedlings. Root developments were observed from the tap and lateral root. The number, length and diameter of both roots-typed of B. cylindrica, B. sexangula and C. tagal seedlings significantly decreased with increasing salt concentration with optimum development at 0.5% salinity. By contrast, the number, length, and diameter of tap root of R. apiculata seedlings were significantly enhanced by salt with maximal stimulation at 0.5%, and this increase was attenuated by increasing salinity. On the other hand, lateral root development of R. apiculata significantly thrived up to 1.5% salinity then decreasing with the increasing salinity. The different response of root development suggested valuable information for mangrove rehabilitation in North Sumatra and their adaption to withstand salt stress.

Nitrate concentration effects on NO3-N uptake and reduction, growth, and fruit yield in strawberry

NASA Technical Reports Server (NTRS)

Darnell, R. L.; Stutte, G. W.; Sager, J. C. (Principal Investigator)

2001-01-01

Strawberries (Fragaria xananassa Duch. 'Osogrande') were grown hydroponically with three NO3-N concentrations (3.75, 7.5, or 15.0 mM) to determine effects of varying concentration on NO3-N uptake and reduction rates, and to relate these processes to growth and fruit yield. Plants were grown for 32 weeks, and NO3-N uptake and nitrate reductase (NR) activities in roots and shoots were measured during vegetative and reproductive growth. In general, NO3-N uptake rates increased as NO3-N concentration in the hydroponics system increased. Tissue NO3- concentration also increased as external NO3-N concentration increased, reflecting the differences in uptake rates. There was no effect of external NO3-N concentration on NR activities in leaves or roots during either stage of development. Leaf NR activity averaged approximately 360 nmol NO2 formed/g fresh weight (FW)/h over both developmental stages, while NR activity in roots was much lower, averaging approximately 115 nmol NO2 formed/g FW/h. Vegetative organ FW, dry weight (DW), and total fruit yield were unaffected by NO3-N concentration. These data suggest that the inability of strawberry to increase growth and fruit yield in response to increasing NO3-N concentrations is not due to limitations in NO3-N uptake rates, but rather to limitations in NO3- reduction and/or assimilation in both roots and leaves.

Dynamics of the Methanogenic Archaeal Community during Plant Residue Decomposition in an Anoxic Rice Field Soil ▿

PubMed Central

Peng, Jingjing; Lü, Zhe; Rui, Junpeng; Lu, Yahai

2008-01-01

Incorporation of plant residues strongly enhances the methane production and emission from flooded rice fields. Temperature and residue type are important factors that regulate residue decomposition and CH4 production. However, the response of the methanogenic archaeal community to these factors in rice field soil is not well understood. In the present experiment, the structure of the archaeal community was determined during the decomposition of rice root and straw residues in anoxic rice field soil incubated at three temperatures (15°C, 30°C, and 45°C). More CH4 was produced in the straw treatment than root treatment. Increasing the temperature from 15°C to 45°C enhanced CH4 production. Terminal restriction fragment length polymorphism analyses in combination with cloning and sequencing of 16S rRNA genes showed that Methanosarcinaceae developed early in the incubations, whereas Methanosaetaceae became more abundant in the later stages. Methanosarcinaceae and Methanosaetaceae seemed to be better adapted at 15°C and 30°C, respectively, while the thermophilic Methanobacteriales and rice cluster I methanogens were significantly enhanced at 45°C. Straw residues promoted the growth of Methanosarcinaceae, whereas the root residues favored Methanosaetaceae. In conclusion, our study revealed a highly dynamic structure of the methanogenic archaeal community during plant residue decomposition. The in situ concentration of acetate (and possibly of H2) seems to be the key factor that regulates the shift of methanogenic community. PMID:18344350

Antimicrobial and antioxidant activities of Cichorium intybus root extract using orthogonal matrix design.

PubMed

Liu, Haitao; Wang, Quanzhen; Liu, Yuyan; Chen, Guo; Cui, Jian

2013-02-01

Solvent, impregnation time, sonication repetitions, and ultrasonic power were important factors in the process of ultrasound-assisted extraction from chicory (Cichorium intybus) root, while there were no studies about optimizing these 4 factors for extract yield, total phenolic content (TPC), antioxidant, antibacterial, and antifungal activity of the extracts using orthogonal matrix design. The present research demonstrated that the solvent composition played a significant role in the improving extract yield, TPC, antioxidant, and antibacterial activities. The other 3 factors had inequable effect on different purposes, ultrasonic power could improve TPC and antioxidant activity, but long time of extraction lowered antioxidant activity. The TPC increased from 22.34 to 27.87 mg GAE (gallic acid equivalents)/100 g (dry extracts) with increasing solvent polarity. The half inhibition concentration (IC(50,) μg/mL) of the radical scavenging activity of the chicory extracts ranged from 281.00 to 983.33 μg/mL. The content of caffeoylquinic acids of root extract, which was extracted by the optimal combination was 0.104%. Several extracts displayed antibacterial activities against Escherichia coli, Staphylococcus aureus, Bacillus thuringiensis, Bacillus subtilis, and Salmonella typhi, while Penicillium sp. and Aspergillus sp. resisted against all the extracts. Combination of 70% ethanol v/v, 24-h impregnation time, 3 sonication rounds, and 300-W ultrasonic input power was found to be the optimal combination for the chicory extract yield, TPC, antioxidant activity, and antibacterial activity. © 2012 Institute of Food Technologists®

Nickel-tolerant ectomycorrhizal Pisolithus albus ultramafic ecotype isolated from nickel mines in New Caledonia strongly enhance growth of the host plant Eucalyptus globulus at toxic nickel concentrations.

PubMed

Jourand, Philippe; Ducousso, Marc; Reid, Robert; Majorel, Clarisse; Richert, Clément; Riss, Jennifer; Lebrun, Michel

2010-10-01

Ectomycorrhizal (ECM) Pisolithus albus (Cooke & Massee), belonging to the ultramafic ecotype isolated in nickel-rich serpentine soils from New Caledonia (a tropical hotspot of biodiversity) and showing in vitro adaptive nickel tolerance, were inoculated to Eucalyptus globulus Labill used as a Myrtaceae plant-host model to study ectomycorrhizal symbiosis. Plants were then exposed to a nickel (Ni) dose-response experiment with increased Ni treatments up to 60 mg kg( - )(1) soil as extractable Ni content in serpentine soils. Results showed that plants inoculated with ultramafic ECM P. albus were able to tolerate high and toxic concentrations of Ni (up to 60 μg g( - )(1)) while uninoculated controls were not. At the highest Ni concentration tested, root growth was more than 20-fold higher and shoot growth more than 30-fold higher in ECM plants compared with control plants. The improved growth in ECM plants was associated with a 2.4-fold reduction in root Ni concentration but a massive 60-fold reduction in transfer of Ni from root to shoots. In vitro, P. albus strains could withstand high Ni concentrations but accumulated very little Ni in its tissue. The lower Ni uptake by mycorrhizal plants could not be explained by increased release of metal-complexing chelates since these were 5- to 12-fold lower in mycorrhizal plants at high Ni concentrations. It is proposed that the fungal sheath covering the plant roots acts as an effective barrier to limit transfer of Ni from soil into the root tissue. The degree of tolerance conferred by the ultramafic P. albus isolates to growth of the host tree species is considerably greater than previously reported for other ECM. The primary mechanisms underlying this improved growth were identified as reduced Ni uptake into the roots and markedly reduced transfer from root to shoot in mycorrhizal plants. The fact that these positive responses were observed at Ni concentrations commonly observed in serpentinic soils suggests that ultramafic ecotypes of P. albus could play an important role in the adaptation of tree species to soils containing high concentrations of heavy metals and aid in strategies for ecological restoration.

Multiple factors impact the contents of heavy metals in vegetables in high natural background area of China.

PubMed

Gan, Yandong; Wang, Lihong; Yang, Guiqiang; Dai, Jiulan; Wang, Renqing; Wang, Wenxing

2017-10-01

A field survey was conducted to investigate the concentrations of chromium (Cr), nickel (Ni), copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb) in vegetables, corresponding cultivated soils and irrigation waters from 36 open sites in high natural background area of Wuzhou, South China. Redundancy analysis, Spearman's rho correlation analysis and multiple regression analysis were adopted to evaluate the contributions of impacting factors on metal contents in the edible parts of vegetables. This study concluded that leafy and root vegetables had relatively higher metal concentrations and adjusted transfer factor values compared to fruiting vegetables according to nonparametric tests. Plant species, total soil metal content and soil pH value were affirmed as three critical factors with the highest contribution rate among all the influencing factors. The bivariate curve equation models for heavy metals in the edible vegetable tissues were well fitted to predict the metal concentrations in vegetables. The results from this case study also suggested that it could be one of efficient strategies for clean agricultural production and food safety in high natural background area to breed vegetable varieties with low heavy metal accumulation and to enlarge planting scale of these varieties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of Glucosinolates and Flavonoids on Colonization of the Roots of Brassica napus by Azorhizobium caulinodans ORS571

PubMed Central

O'Callaghan, Kenneth J.; Stone, Philip J.; Hu, Xiaojia; Griffiths, D. Wynne; Davey, Michael R.; Cocking, Edward C.

2000-01-01

Plants of Brassica napus were assessed quantitatively for their susceptibility to lateral root crack colonization by Azorhizobium caulinodans ORS571(pXLGD4) (a rhizobial strain carrying the lacZ reporter gene) and for the concentration of glucosinolates in their roots by high-pressure liquid chromatography (HPLC). High- and low-glucosinolate-seed (HGS and LGS) varieties exhibited a relatively low and high percentage of colonized lateral roots, respectively. HPLC showed that roots of HGS plants contained a higher concentration of glucosinolates than roots of LGS plants. One LGS variety showing fewer colonized lateral roots than other LGS varieties contained a higher concentration of glucosinolates than other LGS plants. Inoculated HGS plants treated with the flavonoid naringenin showed significantly more colonization than untreated HGS plants. This increase was not mediated by a naringenin-induced lowering of the glucosinolate content of HGS plant roots, nor did naringenin induce bacterial resistance to glucosinolates or increase the growth of bacteria. The erucic acid content of seed did not appear to influence colonization by azorhizobia. Frequently, leaf assays are used to study glucosinolates and plant defense; this study provides data on glucosinolates and bacterial colonization in roots and describes a bacterial reporter gene assay tailored easily to the study of ecologically important phytochemicals that influence bacterial colonization. These data also form a basis for future assessments of the benefits to oilseed rape plants of interaction with plant growth-promoting bacteria, especially diazotrophic bacteria potentially able to extend the benefits of nitrogen fixation to nonlegumes. PMID:10788398

Predisposing factors to severe external root resorption associated to orthodontic treatment.

PubMed

Picanço, Gracemia Vasconcelos; de Freitas, Karina Maria Salvatore; Cançado, Rodrigo Hermont; Valarelli, Fabricio Pinelli; Picanço, Paulo Roberto Barroso; Feijão, Camila Pontes

2013-01-01

The aim of this study was to evaluate predisposing factors among patients who developed moderate or severe external root resorption (Malmgren's grades 3 and 4), on the maxillary incisors, during fixed orthodontic treatment in the permanent dentition. Ninety-nine patients who underwent orthodontic treatment with fixed edgewise appliances were selected. Patients were divided into two groups: G1 - 50 patients with no root resorption or presenting only apical irregularities (Malmgren's grades 0 and 1) at the end of the treatment, with mean initial age of 16.79 years and mean treatment time of 3.21 years; G2 - 49 patients presenting moderate or severe root resorption (Malmgren's grades 3 and 4) at the end of treatment on the maxillary incisors, with mean initial age of 19.92 years and mean treatment time of 3.98 years. Periapical radiographs and lateral cephalograms were evaluated. Factors that could influence the occurrence of severe root resorption were also recorded. Statistical analysis included chi-square tests, Fisher's exact test and independent t tests. The results demonstrated significant difference between the groups for the variables: Extractions, initial degree of root resorption, root length and crown/root ratio at the beginning, and cortical thickness of the alveolar bone. It can be concluded that: Presence of root resorption before the beginning of treatment, extractions, reduced root length, decreased crown/root ratio and thin alveolar bone represent risk factors for severe root resorption in maxillary incisors during orthodontic treatment.

A dynamic growth model of vegetative soya bean plants: model structure and behaviour under varying root temperature and nitrogen concentration

NASA Technical Reports Server (NTRS)

Lim, J. T.; Wilkerson, G. G.; Raper, C. D. Jr; Gold, H. J.

1990-01-01

A differential equation model of vegetative growth of the soya bean plant (Glycine max (L.) Merrill cv. Ransom') was developed to account for plant growth in a phytotron system under variation of root temperature and nitrogen concentration in nutrient solution. The model was tested by comparing model outputs with data from four different experiments. Model predictions agreed fairly well with measured plant performance over a wide range of root temperatures and over a range of nitrogen concentrations in nutrient solution between 0.5 and 10.0 mmol NO3- in the phytotron environment. Sensitivity analyses revealed that the model was most sensitive to changes in parameters relating to carbohydrate concentration in the plant and nitrogen uptake rate.

Effect of cadmium accumulation on mineral nutrient levels in vegetable crops: potential implications for human health.

PubMed

Yang, Danping; Guo, Zhiqiang; Green, Iain D; Xie, Deti

2016-10-01

Consumption of vegetables is often the predominant route whereby humans are exposed to the toxic metal Cd. Health impacts arising from Cd consumption may be influenced by changes in the mineral nutrient content of vegetables, which may occur when plants are exposed to Cd. Here, we subjected model root (carrot) and leaf (lettuce) vegetables to soil Cd concentrations of 0.3, 1.5, 3.3, and 9.6 μg g(-1) for 10 weeks to investigate the effect of Cd exposure on Cd accumulation, growth performance, and mineral nutrient homeostasis. The findings demonstrated that Cd accumulation in lettuce (20.1-71.5 μg g(-1)) was higher than that in carrot (3.2-27.5 μg g(-1)), and accumulation exceeded the maximum permissible Cd concentration in vegetables when soil contained more than 3.3 μg g(-1) of Cd. There was a marked hormetic effect on carrot growth at a soil Cd concentration of 3.3 μg g(-1), but increasing the Cd concentration to 9.6 μg g(-1) caused decreased growth in both crops. Additionally, in most cases, there was a positive correlation between Cd and the mineral nutrient content of vegetables, which was due to physiological changes in the plants causing increased uptake and/or translocation. This may suggest a general mechanism whereby the plant compensated for disrupted mineral nutrient metabolism by increasing nutrient supply to its tissues. Increased nutrient levels could potentially offset some risks posed to humans by increased Cd levels in crops, and we therefore suggest that changes in mineral nutrient levels should be included more widely in the risk assessment of potentially toxic metal contamination. Graphical abstract The Cd concentration (μg g-1 in dry matter) in the root, shoot and translocation factor (TF) of Cd from root to shoot in the carrot and lettuce, and the percentage of root Cd to the gross Cd contents (%) in carrot (C) and lettuce (D) exposed to soil Cd (0 (control), 1, 3, and 9 μg g-1) for 70 days. Values are means ± SD (n = 5).

Vermicompost humic acids modulate the accumulation and metabolism of ROS in rice plants.

PubMed

García, Andrés Calderín; Santos, Leandro Azevedo; de Souza, Luiz Gilberto Ambrósio; Tavares, Orlando Carlos Huertas; Zonta, Everaldo; Gomes, Ernane Tarcisio Martins; García-Mina, José Maria; Berbara, Ricardo Luis Louro

2016-03-15

This work aims to determine the reactive oxygen species (ROS) accumulation, gene expression, anti-oxidant enzyme activity, and derived effects on membrane lipid peroxidation and certain stress markers (proline and malondialdehyde-MDA) in the roots of unstressed and PEG-stressed rice plants associated with vermicompost humic acid (VCHA) application. The results show that the application of VCHA to the roots of unstressed rice plants caused a slight but significant increase in root ROS accumulation and the gene expression and activity of the major anti-oxidant enzymes (superoxide dismutase and peroxidase). This action did not have negative effects on root development, and an increase in both root growth and root proliferation occurred. However, the root proline and MDA concentrations and the root permeability results indicate the development of a type of mild stress associated with VCHA application. When VCHA was applied to PEG-stressed plants, a clear alleviation of the inhibition in root development linked to PEG-mediated osmotic stress was observed. This was associated with a reduction in root ROS production and anti-oxidant enzymatic activity caused by osmotic stress. This alleviation of stress caused by VCHA was also reflected as a reduction in the PEG-mediated concentration of MDA in the root as well as root permeability. In summary, the beneficial action of VCHA on the root development of unstressed or PEG-stressed rice plants clearly involves the modulation of ROS accumulation in roots. Copyright © 2016 Elsevier GmbH. All rights reserved.

Relationships between Nutrient Heterogeneity, Root Growth, and Hormones: Evidence for Interspecific Variation

PubMed Central

Dong, Jia; Jones, Robert H.; Mou, Pu

2018-01-01

(1) Background: Plant roots respond to nutrients through root architecture that is regulated by hormones. Strong inter-specific variation in root architecture has been well documented, but physiological mechanisms that may control the variation have not. (2) Methods: We examined correlations between root architecture and hormones to seek clues on mechanisms behind root foraging behavior. In the green house at Beijing Normal University, hydroponic culture experiments were used to examine the root responses of four species—Callistephus chinensis, Solidago canadensis, Ailanthus altissima, Oryza sativa—to two nitrogen types (NO3− or NH4+), three nitrogen concentrations (low, medium, and high concentrations of 0.2, 1, and 18 mM, respectively) and two ways of nitrogen application (stable vs. variable). The plants were harvested after 36 days to measure root mass, 1st order root length, seminal root length for O. sativa, density of the 1st order laterals, seminal root number for O. sativa, the inter-node length of the 1st order laterals, and root hormone contents of indole-3-acetic acid, abscisic acid, and cytokinins (zeatin + zeatinriboside). (3) Results: Species differed significantly in their root architecture responses to nitrogen treatments. They also differed significantly in hormone responses to the nitrogen treatments. Additionally, the correlations between root architecture and hormone responses were quite variable across the species. Each hormone had highly species-specific relationships with root responses. (4) Conclusions: Our finding implies that a particular root foraging behavior is probably not controlled by the same biochemical pathway in all species. PMID:29495558

Macro- and microelement distribution in organs of Glyceria maxima and biomonitoring applications.

PubMed

Klink, Agnieszka; Stankiewicz, Andrzej; Wisłocka, Magdalena; Polechońska, Ludmiła

2014-07-01

The content of nutrients (N, P, K, Ca and Mg) and of trace metals (Fe, Cu, Mn, Zn, Pb, Cd, Co and Ni) in water, bottom sediments and various organs of Glyceria maxima from 19 study sites selected in the Jeziorka River was determined. In general, the concentrations of nutrients recorded in the plant material decreased in the following order: leaf>root>rhizome>stem, while the concentrations of the trace elements showed the following accumulation scheme: root>rhizome>leaf>stem. The bioaccumulation and transfer factors for nutrients were significantly higher than for trace metals. G. maxima from agricultural fields was characterised by the highest P and K concentrations in leaves, and plants from forested land contained high Zn and Ni amounts. However, the manna grass from small localities showed high accumulation of Ca, Mg and Mn. Positive significant correlations between Fe, Cu, Zn, Cd, Co and Ni concentrations in water or sediments and their concentrations in plant indicate that G. maxima may be employed as a biomonitor of trace element contamination. Moreover, a high degree of similarity was noted between self-organizing feature map (SOFM)-grouped sites of comparable quantities of elements in the water and sediments and sites where G. maxima had a corresponding content of the same elements in its leaves. Therefore, SOFM could be recommended in analysing ecological conditions of the environment from the perspective of nutrients and trace element content in different plant species and their surroundings.

Flavonoids released by carrot (Daucus carota) seedlings stimulate hyphal development of vesicular-arbuscular mycorrhizal fungi in the presence of optimal CO2 enrichment.

PubMed

Poulin, M J; Bel-Rhlid, R; Piché, Y; Chênevert, R

1993-10-01

Carbon dioxide has been previously identified as a critical volatile factor that stimulates hyphal growth ofGigaspora margarita, a vesiculararbuscular mycorrhizal fungus, and we determined the optimal concentration at 2.0%. The beneficial effect of CO2 on fungal development is also visible in the presence of stimulatory (quercetin, myricetin) or inhibitory (naringenin) flavonoids. Sterile root exudates from carrot seedlings stimulate the hyphal development ofG. margarita in the presence of optimal CO2 enrichment. Three flavonols (quercetin, kaempferol, rutin or quercetin 3-rutinoside) and two flavones (apigenin, luteolin) were identified in carrot root exudates by means of HPLC retention time. Flavonols like quercetin and kaempferol are known to have stimulatory effects on hyphal growth ofG. margarita.

Effect of microcystins on root growth, oxidative response, and exudation of rice (Oryza sativa).

PubMed

Cao, Qing; Rediske, Richard R; Yao, Lei; Xie, Liqiang

2018-03-01

A 30 days indoor hydroponic experiment was carried out to evaluate the effect of microcystins (MCs) on rice root morphology and exudation, as well as bioaccumulation of MCs in rice. MCs were bioaccumulated in rice with the greatest concentrations being observed in the leaves (113.68μgg -1 Fresh weight (FW)) when exposed to 500μgL -1 MCs. Root activity at 500μgL -1 decreased 37%, compared to the control. MCs also induced disruption of the antioxidant system and lipid peroxidation in rice roots. Root growth was significantly inhibited by MCs. Root weight, length; surface area and volume were significantly decreased, as well as crown root number and lateral root number. After 30 days exposure to MCs, an increase was found in tartaric acid and malic acid while the other organic acids were not affected. Glycine, tyrosine, and glutamate were the only amino acids stimulated at MCs concentrations of 500μgL -1 . Similarly, dissolved organic carbon (DOC) and carbohydrate at 50 and 500μgL -1 treatments were significantly increased. The increase of DOC and carbohydrate in root exudates was due to rice root membrane permeability changes induced by MCs. Overall, this study indicated that MCs significantly inhibited rice root growth and affected root exudation. Copyright © 2017 Elsevier Inc. All rights reserved.

Fate of oxygen losses from Typha domingensis (Typhaceae) and Cladium jamaicense (Cyperaceae) and consequences for root metabolism

USGS Publications Warehouse

Chabbi, A.; McKee, K.L.; Mendelssohn, I.A.

2000-01-01

The objective of this work was to determine whether radial oxygen loss (ROL) from roots of Typha domingensis and Cladium jamaicense creates an internal oxygen deficiency or, conversely, indicates adequate internal aeration and leakage of excess oxygen to the rhizosphere. Methylene blue in agar was used to quantify oxygen leakage. Typha's roots had a higher porosity than Cladium's and responded to flooding treatment by increasing cortical air space, particularly near the root tips. A greater oxygen release, which occurred along the subapical root axis, and an increase in rhizosphere redox potential (Eh) over time were associated with the well-developed aerenchyma system in Typha. Typha roots, regardless of oxygen release pattern, showed low or undetectable alcohol dehydrogenage (ADH) activity or ethanol concentrations, indicating that ROL did not cause internal deficiencies. Cladium roots also releases oxygen, but this loss primarily occurred at the root tips and was accompanied by increased root ADH activity and ethanol concentrations. These results support the hypothesis that oxygen release by Cladium is accompanied by internal deficiencies of oxygen sufficient to stimulate alcoholic fermentation and helps explain Cladium's lesser flood tolerance in comparison with Typha.

Biomass and nutrient concentration of sweet corn roots and shoots under organic amendments application.

PubMed

Ahmad, Amjad A; Fares, Ali; Paramasivam, Sivapatham; Elrashidi, Moustafa A; Savabi, Reza M

2009-09-01

Two field experiments were conducted at the Waimanalo research station on the island of O'ahu, Hawaii to study the effect of chicken (CM) and dairy (DM) manures on biomass and nutrient concentration in sweet corn roots and shoots. Sweet corn (super sweet 10, Zea Mays L. subsp. mays) was grown for two consecutive growing seasons under four rates of application (0, 168, 337, and 672 kg ha(-1) total N equivalent) and one time (OTA) or two time (TTA) applications of organic manure types and rates. There were significant effects of types, rates, and number of manure applications on dry biomass and macro- and micro-nutrient concentration in roots and shoots tissues. Results of root tissue indicated a significant accumulation of N and C under CM and DM treatments compared with the control treatment. Manure application rates significantly increased the accumulation of N and C in root tissue. Dry weight of roots and shoots and both macro- and micro-nutrient contents in the plant tissues significantly increased under TTA treatment compared with OTA treatment. There was a significant correlation (r(2) = 0.46 to 0.81) between root biomass, macro-, and micro-nutrient contents during both growing seasons. The results of the study indicates that amending soils with CM at the highest application rate provided the best crop performance in terms of root and shoot biomass, crop N, C, and other macro- and micro-nutrients.

Imaging O2 changes induced in tomato roots by fungal pathogen

NASA Astrophysics Data System (ADS)

Rubol, S.; Turco, E.; Rodeghiero, M.; Bellin, A.

2014-12-01

In the last decade, planar optodes have demonstrated to be a useful non-invasive tool to monitor real time oxygen concentrations in a wide range of applications. However, only limited investigations have been carried out to explore the use of optodes in plant respiration studies. In particular, their use to study plant-pathogen interactions has been not deeply investigated. Here, we present for the first time an in vitro experimental setup capable to depict the dynamical effects of the fungal pathogen Fusarium oxysporum f.sp. lycopersici (Fol) on tomato roots by the use of a recently developed optical non-invasive optode oxygen sensor (Visisens, Presens, Germany). Fol is a soil-borne pathogen and the causal agent of wilt in tomato plants, a destructive worldwide disease. The interaction Fol-tomato is widely accepted as a model system in plant pathology. In this work, oxygen concentrations are monitored continuously in time and considered a proxy for root respiration and metabolic activity. The experimental procedure reveals three different dynamic stages: 1) a uniform oxygen consumption in tomato roots earlier before pathogen colonization, 2) a progressive decrease in the oxygen concentration indicating a high metabolic activity as soon as the roots were surrounded and colonized by the fungal mycelium, and 3) absence of root respiration, as a consequence of root death. Our results suggest the ability of the fungal mycelium to move preferentially towards and along the root as a consequence of the recognition event.

Can we predict uranium bioavailability based on soil parameters? Part 2: soil solution uranium concentration is not a good bioavailability index.

PubMed

Vandenhove, H; Van Hees, M; Wannijn, J; Wouters, K; Wang, L

2007-01-01

The present study aimed to quantify the influence of soil parameters on uranium uptake by ryegrass. Ryegrass was established on eighteen distinct soils, spiked with (238)U. Uranium soil-to-plant transfer factors (TF) ranged from 0.0003 to 0.0340kgkg(-1). There was no significant relation between the U soil-to-plant transfer (or total U uptake or flux) and the uranium concentration in the soil solution or any other soil factor measured, nor with the U recovered following selective soil extractions. Multiple linear regression analysis resulted in a significant though complex model explaining up to 99% of variation in TF. The influence of uranium speciation on uranium uptake observed was featured: UO(2)(+2), uranyl carbonate complexes and UO(2)PO(4)(-) seem the U species being preferentially taken up by the roots and transferred to the shoots. Improved correlations were obtained when relating the uranium TF with the summed soil solution concentrations of mentioned uranium species.

Soil, Leaf and Root Ecological Stoichiometry of Caragana korshinskii on the Loess Plateau of China in Relation to Plantation Age

PubMed Central

Zeng, Quanchao; Lal, Rattan; Chen, Yanan; An, Shaoshan

2017-01-01

Caragana korshinskii, a leguminous shrub, a common specie, is widely planted to prevent soil erosion on the Loess Plateau. The objective of this study was to determine how the plantation ages affected soil, leaf and root nutrients and ecological stoichiometry. The chronosequence ages of C. korshinskii plantations selected for this study were 10, 20 and 30 years. Soil organic carbon (SOC) and soil total nitrogen (STN) of C. korshinskii plantations significantly increased with increase in the chronosequence age. However, soil total phosphorous (STP) was not affected by the chronosequence age. The soil C: N ratio decreased and the soil C: P and N: P ratios increased with increasing plantation age. The leaf and root concentrations of C, N, and P increased and the ratios C: N, C: P, and N: P decreased with age increase. Leaf N: P ratios were >20, indicating that P was the main factor limiting the growth of C. korshinskii. This study also demonstrated that the regeneration of natural grassland (NG) effectively preserved and enhanced soil nutrient contents. Compared with NG, shrub lands (C. korshinskii) had much lower soil nutrient concentrations, especially for long (>20 years) chronosequence age. Thus, the regeneration of natural grassland is an ecologically beneficial practice for the recovery of degraded soils in this area. PMID:28076357

Xylem transport and gene expression play decisive roles in cadmium accumulation in shoots of two oilseed rape cultivars (Brassica napus).

PubMed

Wu, Zhichao; Zhao, Xiaohu; Sun, Xuecheng; Tan, Qiling; Tang, Yafang; Nie, Zhaojun; Hu, Chengxiao

2015-01-01

Cadmium (Cd) is a toxic metal which harms human health through food chains. The mechanisms underlying Cd accumulation in oilseed rape are still poorly understood. Here, we investigated the physiological and genetic processes involved in Cd uptake and transport of two oilseed rape cultivars (Brassica napus). L351 accumulates more Cd in shoots but less in roots than L338. A scanning ion-selective electrode technique (SIET) and uptake kinetics of Cd showed that roots were not responsible for the different Cd accumulation in shoots since L351 showed a lower Cd uptake ability. However, concentration-dependent and time-dependent dynamics of Cd transport by xylem showed L351 exhibited a superordinate capacity of Cd translocation to shoots. Additionally, the Cd concentrations of shoots and xylem sap showed a great correlation in both cultivars. Furthermore, gene expression levels related to Cd uptake by roots (IRT1) and Cd transport by xylem (HMA2 and HMA4) were consistent with the tendencies of Cd absorption and transport at the physiological level respectively. In other words, L351 had stronger gene expression for Cd transport but lower for Cd uptake. Overall, results revealed that the process of Cd translocation to shoots is a determinative factor for Cd accumulation in shoots, both at physiological and genetic levels. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

Characterization and Scaling of Black Carbon Aerosol Concentration with City Population Based on In-Situ Measurements and Analysis

NASA Astrophysics Data System (ADS)

Paredes-Miranda, G.; Arnott, W. P.; Moosmuller, H.

2010-12-01

The global trend toward urbanization and the resulting increase in city population has directed attention toward air pollution in megacities. A closely related question of importance for urban planning and attainment of air quality standards is how pollutant concentrations scale with city population. In this study, we use measurements of light absorption and light scattering coefficients as proxies for primary (i.e., black carbon; BC) and total (i.e., particulate matter; PM) pollutant concentration, to start addressing the following questions: What patterns and generalizations are emerging from our expanding data sets on urban air pollution? How does the per-capita air pollution vary with economic, geographic, and meteorological conditions of an urban area? Does air pollution provide an upper limit on city size? Diurnal analysis of black carbon concentration measurements in suburban Mexico City, Mexico, Las Vegas, NV, USA, and Reno, NV, USA for similar seasons suggests that commonly emitted primary air pollutant concentrations scale approximately as the square root of the urban population N, consistent with a simple 2-d box model. The measured absorption coefficient Babs is approximately proportional to the BC concentration (primary pollution) and thus scales with the square root of population (N). Since secondary pollutants form through photochemical reactions involving primary pollutants, they scale also with square root of N. Therefore the scattering coefficient Bsca, a proxy for PM concentration is also expected to scale with square root of N. Here we present light absorption and scattering measurements and data on meteorological conditions and compare the population scaling of these pollutant measurements with predictions from the simple 2-d box model. We find that these basin cities are connected by the square root of N dependence. Data from other cities will be discussed as time permits.

Assessing the phytoavailability of arsenic and phosphorus to corn plant after the addition of an acrylic copolymer to polluted soils.

PubMed

Mansouri, Tahereh; Golchin, Ahmad; Kouhestani, Hossein

2017-08-13

Soil pollution by arsenic increases the potential risk of arsenic entrance into the food chain. The usefulness of maleic anhydride- styrene- acrylic acid copolymer on the mobility and phytoavailability of arsenic was evaluated. Treatments were the concentrations of acrylic copolymer (0, 0.05, 0.10, and 0.20% w/w) and the concentrations of soil total arsenic (0, 6, 12, 24, 48, and 96 mg kg -1 ). Sodium arsenate was added in appropriate amounts to subsamples of an uncontaminated soil to give contaminated soils with different levels of arsenic. The contaminated soils were subjected to a greenhouse experiment using corn as the test crop. The results showed that contamination of soil by arsenic increased the concentrations of soil available arsenic, root and aerial parts arsenic. By the use of acrylic copolymer, the concentration of available arsenic in the soil and the accumulation of arsenic in the root and aerial parts of the corn plant decreased but the dry weights of the root and aerial parts increased significantly. When the concentration of soil total arsenic was 96 mg kg -1 , the application of copolymer at the concentration of 0.20% w/w reduced the concentrations of arsenic in soil, root, and aerial parts by 62.53, 43.65, and 37.00% respectively, indicating that application of acrylic copolymer immobilized arsenic in soils.

The Relationship Between Temperature and Gas Concentration Fluctuation Rates at an Air-Water Interface

NASA Astrophysics Data System (ADS)

Asher, W. E.; Jessup, A. T.; Liang, H.; Zappa, C. J.

2008-12-01

The air-sea flux, F, of a sparingly soluble nonreactive gas can be expressed as F = kG(CS-CW), where kG is the gas transfer velocity, CS is the concentration of gas that would be expected in the water if the system were in Henry's Gas Law equilibrium, and CW is the gas concentration in the bulk water. An analogous relationship for the net heat flux can also be written using the heat transfer velocity, kH, and the bulk-skin temperature difference in the aqueous phase. Surface divergence theory for the air-water transfer of gas and heat predicts that kG and kH will scale as the square root of the surface divergence rate, r. However, because of the interaction between diffusivity and the scale depth of the surface divergences, the scale factor for heat is likely to be different from the scale factor for gases. Infrared imagery was used to measure the timescales of variations in temperature at a water surface and laser-induced fluorescence (LIF) was used to measure temporal fluctuations in aqueous-phase concentrations of carbon dioxide (CO2) at a water surface. The rate at which these temperature and concentration fluctuations occur is then assumed to be related to r. The divergence rates derived for temperature from the IR images can be compared to the rates for gas derived from the LIF measurements to understand how r estimated from the two measurements differ. The square root of r is compared to concurrently measured kG for helium and sulfur hexafluoride to test the assumption that r1/2 scales with kG. Additionally, we measured kH using the active controlled flux technique, and those heat transfer velocities can also be used to test for a r1/2 dependence. All measurements reported here were made in the APL-UW synthetic jet array facility.

Development of suitable hydroponics system for phytoremediation of arsenic-contaminated water using an arsenic hyperaccumulator plant Pteris vittata.

PubMed

Huang, Yi; Miyauchi, Keisuke; Inoue, Chihiro; Endo, Ginro

2016-01-01

In this study, we found that high-performance hydroponics of arsenic hyperaccumulator fern Pteris vittata is possible without any mechanical aeration system, if rhizomes of the ferns are kept over the water surface level. It was also found that very low-nutrition condition is better for root elongation of P. vittata that is an important factor of the arsenic removal from contaminated water. By the non-aeration and low-nutrition hydroponics for four months, roots of P. vittata were elongated more than 500 mm. The results of arsenate phytofiltration experiments showed that arsenic concentrations in water declined from the initial concentrations (50 μg/L, 500 μg/L, and 1000 μg/L) to lower than the detection limit (0.1 μg/L) and about 80% of arsenic removed was accumulated in the fern fronds. The improved hydroponics method for P. vittata developed in this study enables low-cost phytoremediation of arsenic-contaminated water and high-affinity removal of arsenic from water.

Specialized 'dauciform' roots of Cyperaceae are structurally distinct, but functionally analogous with 'cluster' roots.

PubMed

Shane, Michael W; Cawthray, Gregory R; Cramer, Michael D; Kuo, John; Lambers, Hans

2006-10-01

When grown in nutrient solutions of extremely low [P] (

Kinetin increases chromium absorption, modulates its distribution, and changes the activity of catalase and ascorbate peroxidase in Mexican Palo Verde

PubMed Central

Zhao, Yong; Peralta-Videa, Jose R.; Lopez-Moreno, Martha L.; Ren, Minghua; Saupe, Geoffrey; Gardea-Torresdey, Jorge L

2015-01-01

This report shows, for the first time, the effectiveness of the phytohormone kinetin (KN) in increasing Cr translocation from roots to stems in Mexican Palo Verde. Fifteen-day-old seedlings, germinated in soil spiked with Cr(III) and (VI) at 60 and 10 mg kg−1, respectively, were watered every other day for 30 days with a KN solution at 250 μM. Samples were analyzed for catalase (CAT) and ascorbate peroxidase (APOX) activities, Cr concentration, and Cr distribution in tissues. Results showed that KN reduced CAT but increased APOX in the roots of Cr(VI)-treated plants. In the leaves, KN reduced both CAT and APOX in Cr(III) but not in Cr(VI)-treated plants. However, KN increased total Cr concentration in roots, stems, and leaves by 45%, 103%, and 72%, respectively, compared to Cr(III) alone. For Cr(VI), KN increased Cr concentrations in roots, stems, and leaves, respectively, by 53%, 129%, and 168%, compared to Cr(VI) alone. The electron probe microanalyzer results showed that Cr was mainly located at the cortex section in the root, and Cr distribution was essentially homogenous in stems. However, proven through X-ray images, Cr(VI)-treated roots and stems had more Cr accumulation than Cr(III) counterparts. KN increased the Cr translocation from roots to stems. PMID:21174467

Carbohydrate and elicitor enhanced withanolide (withaferin A and withanolide A) accumulation in hairy root cultures of Withania somnifera (L.).

PubMed

Doma, Madhavi; Abhayankar, Gauri; Reddy, V D; Kavi Kishor, P B

2012-07-01

Leaves of Withania somnifera contained more withaferin A and withanolide A than roots indicating that these compounds mainly accumulate in leaves. With an increase in age of the plant, withaferin A was enhanced with a corresponding decrease in withanolide A. Hairy root cultures were induced from leaf explants using Agrobacterium rhizogenes and the transgenic nature of hairy roots was confirmed by partial isolation and sequencing of rolB gene, which could not be amplified in untransformed plant parts. In hairy roots, withaferin A accumulated at 2, 3 and 4% but not at 6% sucrose, the highest amount being 1733 microg/g dry weight at 4% level. High and equal amounts of withaferin A and withanolide A accumulated (890 and 886 microg/g dry tissue respectively) only at 3% sucrose. Increasing concentrations of glucose enhanced withaferin A and it peaked at 5% level (3866 microg/g dry tissue). This amount is 2842 and 34% higher compared to untransformed roots and leaves (collected from 210-day-old plants) respectively. Withanolide A was detected at 5% glucose but not at other concentrations. While chitosan and nitric oxide increased withaferin A, jasmonic acid decreased it. Acetyl salicylic acid stimulated accumulation of both withaferin A and withanolide A at higher concentrations. Triadimefon, a fungicide, enhanced withaferin A by 1626 and 3061% (not detected earlier) compared to hairy and intact roots respectively.

Uranium fate in wetland mesocosms: Effects of plants at two ...

EPA Pesticide Factsheets

Small-scale continuous flow wetland mesocosms (~0.8 L) were used to evaluate how plant roots under different iron loadings affect uranium (U) mobility. When significant concentrations of ferrous iron (Fe) were present at circumneutral pH values, U concentrations in root exposed sediments were an order of magnitude greater than concentrations in root excluded sediments. Micro X-ray absorption near-edge structure (µ-XANES) spectroscopy indicated that U was associated with the plant roots primarily as U(VI) or U(V), with limited evidence of U(IV). Micro X-ray fluorescence (µ-XRF) of plant roots suggested that for high iron loading at circumneutral pH, U was co-located with Fe, perhaps co-precipitated with root Fe plaques, while for low iron loading at a pH of ~4 the correlation between U and Fe was not significant, consistent with previous observations of U associated with organic matter. Quantitative PCR analyses indicated that the root exposed sediments also contained elevated numbers of Geobacter spp., which are likely associated with enhanced iron cycling, but may also reduce mobile U(VI) to less mobile U(IV) species. There are significant uncertainties regarding the environmental fate of uranium (U) and efforts to minimize U exposures require understanding of its mobility in environmental systems. Much research has focused on sequestering U as solids within groundwater aquifers, where localized risks can be controlled.1 Subsurface sequestration limits t

Physiological effects of autotoxicity due to DHAP stress on Picea schrenkiana regeneration

PubMed Central

Yang, Li; Ruan, Xiao; Jiang, Dean; Zhang, Jianhong; Pan, Cunde; Wang, Qiang

2017-01-01

Picea Schrenkiana as one of the most important zonal vegetation was an endemic species in Middle Asia. Natural regeneration of P. Schrenkiana is a long existing problem troubling scientists. The autotoxicity of 3,4-dihydroxy-acetophenone (DHAP) was found to be a causative factor causing the failure of P. Schrenkiana natural regeneration. The effects of concentrations of DHAP treatment on the viability of root cell, activities of antioxidant enzymes and levels of P. Schrenkiana phytohormones were performed to disclose the physiological mechanism of DHAP autotoxicity. It was observed that high concentration of DHAP could inhibit the seed germination and seedling growth, but had a hormesis at low concentrations. Analyses showed that the root cells significantly lost their viability treated with high DHAP. The enzymes activities of seedlings were significantly stimulated by the treatment of 0.5 mM DHAP to give a transient increase and then decrease as DHAP concentration increased to 1.0 mM except for GR (glutathione reductase) in which DHAP treatment had little effect on its activity. Comparing with the control, an increase in the levels of phytohormones ZT (zeatin), GA3 (gibberellic acid) and IAA (indole acetic acid) was induced by the treatment of DHAP at low concentrations (0.1–0.25 mM), but the significant deficiency was found treated by high concentrations (0.5–1.0 mM). In addition, the ABA (abscisic acid) level increased in all experimental observations. These results suggested that DHAP significantly affected indices of growth and physiology, and provided some new information about different effect in P. Schrenkiana treated with DHAP. PMID:28481896

Active carbon-pools in rhizosphere of wheat (Triticum aestivum L.) grown under elevated atmospheric carbon dioxide concentration in a Typic Haplustept in sub-tropical India.

PubMed

Kant, Pratap C B; Bhadraray, Subhendu; Purakayastha, T J; Jain, Vanita; Pal, Madan; Datta, S C

2007-05-01

Study on active and labile carbon-pools can serve as a clue for soil organic carbon dynamics on exposure to elevated level of CO2. Therefore, an experimental study was conducted in a Typic Haplustept in sub-tropical semi-arid India with wheat grown in open top chambers at ambient (370 micromol mol-1) and elevated (600 micromol mol-1) concentrations of atmospheric CO2. Elevated atmospheric CO2 caused increase in yield and carbon uptake by all plant parts, and their preferential partitioning to root. Increases in fresh root weight, volume and length have also been observed. Relative contribution of medium-sized root to total root length increased at the expense of very fine roots at elevated CO2 level. All active carbon-fractions gained due to elevated atmospheric CO2 concentration, and the order followed their relative labilities. All the C-pools have recorded a significant increase over initial status, and are expected to impart short-to-medium-term effect on soil carbon sequestration.

[Allelopathy of grape root aqueous extracts].

PubMed

Li, Kun; Guo, Xiu-wu; Guo, Yin-shan; Li, Cheng-xiang; Xie, Hong-gang; Hu, Xi-xi; Zhang, Li-heng; Sun, Ying-ni

2010-07-01

Taking the tissue-cultured seedlings of grape cultivar Red Globe as test objects, this paper examined the effects of their root aqueous extracts on seedling's growth, with the allelochemicals identified by LC-MS. The results showed that 0.02 g x ml(-1) (air-dried root mass in aqueous extracts volume; the same below), 0.1 g x ml(-1), and 0.2 g x ml(-1) of the aqueous extracts inhibited the growth of the seedlings significantly, and the inhibition effect increased with increasing concentration of the extracts. The identified allelochemicals of the extracts included p-hydroxybenzoic acid, salicylic acid, phenylpropionic acid, and coumaric acid. Pot experiment showed that different concentration (0.1, 1, and 10 mmol x L(-1)) salicylic acid and phenylpropionic acid inhibited the seedling' s growth remarkably. With the increasing concentration of the two acids, the plant height, stem diameter, shoot- and root fresh mass, leaf net photosynthetic rate and starch content, and root activity of the seedlings decreased, while the leaf soluble sugar and MDA contents increased. No obvious change pattern was observed in leaf protein content.

Phenolic characterization and variability in leaves, stems and roots of Micro-Tom and patio tomatoes, in response to nitrogen limitation.

PubMed

Larbat, Romain; Paris, Cédric; Le Bot, Jacques; Adamowicz, Stéphane

2014-07-01

Phenolics are implicated in the defence strategies of many plant species rendering their concentration increase of putative practical interest in the field of crop protection. Little attention has been given to the nature, concentration and distribution of phenolics within vegetative organs of tomato (Solanum lycopersicum. L) as compared to fruits. In this study, we extensively characterized the phenolics in leaves, stems and roots of nine tomato cultivars using high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (LC-MS(n)) and assessed the impact of low nitrogen (LN) availability on their accumulation. Thirty-one phenolics from the four sub-classes, hydroxycinnamoyl esters, flavonoids, anthocyanins and phenolamides were identified, five of which had not previously been reported in these tomato organs. A higher diversity and concentration of phenolics was found in leaves than in stems and roots. The qualitative distribution of these compounds between plant organs was similar for the nine cultivars with the exception of Micro-Tom because of its significantly higher phenolic concentrations in leaves and stems as compared to roots. With few exceptions, the influence of the LN treatment on the three organs of all cultivars was to increase the concentrations of hydroxycinnamoyl esters, flavonoids and anthocyanins and to decrease those of phenolamides. This impact of LN was greater in roots than in leaves and stems. Nitrogen nutrition thus appears as a means of modulating the concentration and composition of organ phenolics and their distribution within the whole plant. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Arbuscular mycorrhizal symbiosis can mitigate the negative effects of night warming on physiological traits of Medicago truncatula L.

PubMed

Hu, Yajun; Wu, Songlin; Sun, Yuqing; Li, Tao; Zhang, Xin; Chen, Caiyan; Lin, Ge; Chen, Baodong

2015-02-01

Elevated night temperature, one of the main climate warming scenarios, can have profound effects on plant growth and metabolism. However, little attention has been paid to the potential role of mycorrhizal associations in plant responses to night warming, although it is well known that symbiotic fungi can protect host plants against various environmental stresses. In the present study, physiological traits of Medicago truncatula L. in association with the arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis were investigated under simulated night warming. A constant increase in night temperature of 1.53 °C significantly reduced plant shoot and root biomass, flower and seed number, leaf sugar concentration, and shoot Zn and root P concentrations. However, the AM association essentially mitigated these negative effects of night warming by improving plant growth, especially through increased root biomass, root to shoot ratio, and shoot Zn and root P concentrations. A significant interaction was observed between R. irregularis inoculation and night warming in influencing both root sucrose concentration and expression of sucrose synthase (SusS) genes, suggesting that AM symbiosis and increased night temperature jointly regulated plant sugar metabolism. Night warming stimulated AM fungal colonization but did not influence arbuscule abundance, symbiosis-related plant or fungal gene expression, or growth of extraradical mycelium, indicating little effect of night warming on the development or functioning of AM symbiosis. These findings highlight the importance of mycorrhizal symbiosis in assisting plant resilience to climate warming.

Bioconcentration of triclosan, methyl-triclosan, and triclocarban in the plants and sediments of a constructed wetland.

PubMed

Zarate, Frederick M; Schulwitz, Sarah E; Stevens, Kevin J; Venables, Barney J

2012-07-01

Constructed wetlands are a potential method for the removal of two pharmaceutical and personal care products from wastewater effluent. Triclosan (TCS; 5-chloro-2-[2,4-dichlorophenoxy]phenol) and triclocarban (TCC; 3,4,4'-trichlorocarbanillide) are antimicrobial agents added to a variety of consumer products whose accumulation patterns in constructed wetlands are poorly understood. Here, we report the accumulation of TCS, its metabolite methyl-triclosan (MTCS; 5-chloro-2-[2,4-dichlorophenoxy]), and TCC in wetland plant tissues and sediments. Three wetland macrophytes: Typha latifolia, Pontederia cordata, and Sagittaria graminea were sampled from a constructed wetland in Denton, Texas, USA. MTCS concentrations were below the method detection limit (MDL) for all species. TCS root tissue concentrations in T. latifolia were significantly greater than root concentrations in P. cordata (mean±SE in ng g(-1): 40.3±11.3 vs. 15.0±1.9, respectively), while for TCC, shoot tissue concentrations in S. graminea were significantly greater than in T. latifolia (22.8±9.3 vs. 9.0 (MDL), respectively). For both TCS and TCC, T. latifolia root tissue concentrations were significantly greater than shoot concentrations (TCS: 40.3±11.3 vs. 17.2±0.2, TCC: 26.0±3.6 vs. 9.0, (MDL)). TCC concentrations in P. cordata roots were significantly greater than in shoots (34.4±5.3 vs. 15.4±2.8, respectively). TCS concentrations in T. latifolia roots and sediments and TCC concentrations in sediments generally decreased from wetland inflow to outflow. To our knowledge, this is the first study documenting species and tissue specific differences in the accumulation of TCS and TCC in plants from an operational constructed wetland. The species specific differences in bioaccumulation suggest TCS and TCC removal from constructed wetlands could be enhanced through targeted plantings. Copyright © 2012 Elsevier Ltd. All rights reserved.

Trunk and root sprouting on residual trees after thinning a Quercus chrysolepis stand

Treesearch

Timothy E. Paysen; Marcia G. Narog; Robert G. Tissell; Melody A. Lardner

1991-01-01

Canyon live oak (Quercus chrysolepis Liebm.) showed sprouting patterns on root and trunk zones foUowing forest thinning. Root sprouting was heaviest on north and east (downhill) sides of residual trees; bole sprouts were concentrated on the south and west (uphill). Root and bole sprouting appeared to be responding to different stimuli, or...

The effects of ropivacaine hydrochloride on the expression of CaMK II mRNA in the dorsal root ganglion neurons.

PubMed

Wen, Xianjie; Lai, Xiaohong; Li, Xiaohong; Zhang, Tao; Liang, Hua

2016-12-01

In this study, we identified the subtype of Calcium/calmodulin-dependent protein kinase II (CaMK II) mRNA in dorsal root ganglion neurons and observed the effects of ropivacaine hydrochloride in different concentration and different exposure time on the mRNA expression. Dorsal root ganglion neurons were isolated from the SD rats and cultured in vitro. The mRNA of the CaMK II subtype in dorsal root ganglion neurons were detected by real-time PCR. As well as, the dorsal root ganglion neurons were treated with ropivacaine hydrochloride in different concentration (1mM,2mM, 3mM and 4mM) for the same exposure time of 4h, or different exposure time (0h,2h,3h,4h and 6h) at the same concentration(3mM). The changes of the mRNA expression of the CaMK II subtype were observed with real-time PCR. All subtype mRNA of the CaMK II, CaMK II α , CaMK II β , CaMK II δ , CaMK II γ , can be detected in dorsal root ganglion neurons. With the increased of the concentration and exposure time of the ropivacaine hydrochloride, all the subtype mRNA expression increased. Ropivacaine hydrochloride up-regulate the CaMK II β , CaMK II δ , CaMK II g mRNA expression with the concentration and exposure time increasing. The nerve blocking or the neurotoxicity of the ropivacaine hydrochloride maybe involved with CaMK II. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Validation of a Cariogenic Biofilm Model to Evaluate the Effect of Fluoride on Enamel and Root Dentine Demineralization.

PubMed

Fernández, Constanza E; Tenuta, Livia M A; Cury, Jaime A

2016-01-01

Due to gingival recession both enamel and root dentine are at risk of developing caries. Both tissues are exposed to a similar environment, however there is not a validated model to evaluate the effect of fluoride on these dental substrates simultaneously. Hence, this study aimed to validate a caries model to evaluate the effect of fluoride to prevent demineralization on enamel and root-dentine. Streptococcus mutans UA159 biofilms were formed on saliva-coated bovine enamel and root dentine slabs (n = 12 per group) mounted in the same well of culture plates. The biofilms were exposed 8×/day to 10% sucrose and treated 2×/day with fluoridated solutions containing 0, 150, 450, or 1,350 ppm F; thus, simulating the use of low to high fluoride concentration toothpastes. The pH values of the culture medium was monitored 2×/day as a biofilm acidogenicity indicator. After 96 h, biofilms were collected for fluoride concentration analysis. The percentage of surface hardness loss (%SHL) was calculated for slabs. The fluoride uptake by the enamel and dentine was also determined. The model showed a dose-response because the biofilm and fluoride uptake increased and %SHL decreased at increasing fluoride concentrations (p < 0.05). Fluoride in the biofilm formed on dentine and fluoride uptake by dentine were higher than those for enamel. With the same fluoride concentration treatment, the percentage of reduction of demineralization was lower for dentine than for enamel. In conclusion, the model was validated in terms of a dose-response effect of fluoride on enamel and root dentine. Furthermore, the findings support the clinical data, suggesting that higher fluoride concentrations are necessary to control caries of root dentine than of enamel.

[Allelopathy of Andrographis paniculata vegetative].

PubMed

Li, Ming; Zhou, Xiao-Yan; Lu, Zhan-Hong

2010-12-01

Andrographis paniculata at vegetative stage were analyzed for the allelopathic effect on cabbage (Brassica chinensis), Radis (Raphanus sativus), and Desmodium styracifolium, and provided the theory reference for their application of compounding planting pattern in practice. Water extracts of Andrographis paniculata root, stem and leaf were used to dispose Brassica chinensis, Raphanus sativus and Desmodium styracifolium seeds, young seedlings. There were allelopathic effect of water extracts of Andrographis paniculata on seed germination of Brassica chinensis, Raphanus sativus and Desmodium styracifolium, but there were difference on allelopathic effect. The suppression effects of roots on seed germination rates of Brassica chinensis showed more significantly, the stems and leaves of Andrographis paniculata on the allelopathic effects on Brassica chinensis seed germination rate index was also significantly higher than the other two receptors plants. Under the treating condition of root, stem and leaf aqueous extracts of Andrographis paniculata, the root growth of receptors seeding mostly showed inhibition effect. Under low concentrations treated. The effects on the seedlings height of Raphanus sativus and Desmodium styracifolium showed the results in which low concentration promoted and high concentration inhibited, and with increasing concentration increased the promotion or inhibition effects. But in the measured concentration range, the effects on the seedlings height of Brassica chinensis were showed promote effect. Within the testing concentration range, water extracts of Andrographis paniculata on allelopathic effects of cabbage (Brassica chinensis), Radis (Raphanus sativus) and Desmodium styracifolium showed allelopathic effect, and roughly showed inhibiti effect. However, showed different effect in which high concentration inhibitied and low concentration promoted to different receptor.

Chromium toxicity tolerance of Solanum nigrum L. and Parthenium hysterophorus L. plants with reference to ion pattern, antioxidation activity and root exudation.

PubMed

UdDin, Islam; Bano, Asghari; Masood, Sajid

2015-03-01

Chromium (Cr), being a highly toxic metal, adversely affects the mineral uptake and metabolic processes in plants when present in excess. The current study was aimed at investigating the Cr accumulation in various plant tissues and its relation to the antioxidation activity and root exudation. Plants were grown in soil spiked with different concentrations of Cr for three weeks in pots and analysed for different growth, antioxidants and ion attributes. Furthermore, plants treated with different concentrations of Cr in pots were shifted to rhizobox-like system for 48h and organic acids were monitored in the mucilage dissolved from the plant root surface, mirroring rhizospheric solution. The results revealed that the Cr application at 1mM increased the shoot fresh and dry weight and root dry weight of Solanum nigrum, whereas the opposite was observed for Parthenium hysterophorus when compared with lower levels of Cr (0.5mM) or control treatment. In both plant species, Cr and Cl concentrations were increased while Ca, Mg and K concentrations in root, shoot and root exudates were decreased with increasing levels of Cr. Higher levels of Cr treatments enhanced the activities of SOD, POD and proline content in leaves of S. nigrum, whereas lower levels of Cr treatment were found to have stimulatory effects in P. hysterophorus. P. hysterophorus exhibited highest exudation of organic acid contents. With increasing levels of Cr treatments, citric acid concentration in root exudates increased by 35% and 44% in S. nigrum, whereas 20% and 76% in P. hysterophorus. Cr toxicity was responsible for the shoot growth reduction of S. nigrum and P. hysterophorus, however, shoot growth response was different at different levels of applied Cr. Consequently, Cr stress negatively altered the plant physiology and biochemistry. However, the enhanced antioxidant production, Cl uptake and root exudation are the physiological and biochemical indicators for the plant adaptations in biotic systems polluted with Cr. Copyright © 2014 Elsevier Inc. All rights reserved.

Soybean NADP-Malic Enzyme Functions in Malate and Citrate Metabolism and Contributes to Their Efflux under Al Stress.

PubMed

Zhou, Ying; Yang, Zhenming; Xu, Yuezi; Sun, Haoran; Sun, Zhitao; Lin, Bao; Sun, Wenjing; You, Jiangfeng

2017-01-01

Malate accumulation has been suggested to balance Al-induced citrate synthesis and efflux in soybean roots. To test this hypothesis, characteristics of Al-induced accumulation and efflux of citrate and malate were compared between two soybean genotypes combining a functional analysis of GmME1 putatively encode a cytosolic NADP-malic enzyme. Similar amounts of citrate were released, and root elongation was equally inhibited before 8 h of Al treatment of Jiyu 70 and Jiyu 62 cultivars. Jiyu 70 began to secrete more citrate and exhibited higher Al resistance than did Jiyu 62 at 12 h. A sustained increase in internal malate and citrate concentrations was observed in Jiyu 70 at 24 h of Al treatment. However, Jiyu 62 decreased its malate concentration at 12 h and its citrate concentration at 24 h of Al treatment. GmME1 localized to the cytoplast and clustered closely with cytosolic malic enzymes AtME2 and SgME1 and was constitutively expressed in the roots. Al treatment induced higher NADP-malic enzyme activities and GmME1 expression levels in Jiyu 70 than in Jiyu 62 within 24 h. Compared with wild-type hairy roots, over-expressing GmME1 in hairy roots ( GmME1 -OE) produced higher expression levels of GmME1 but did not change the expression patterns of either of the putative citrate transporter genes GmAACT1 and GmFRDL or the malate transporter gene GmALMT1 , with or without Al treatment. GmME1 -OE showed a higher internal concentration and external efflux of both citrate and malate at 4 h of Al stress. Lighter hematoxylin staining and lower Al contents in root apices of GmME1 -OE hairy roots indicated greater Al resistance. Comprehensive experimental results suggest that sustaining Al-induced citrate efflux depends on the malate pool in soybean root apices. GmME1 encodes a cytosolic malic enzyme that contributes to increased internal malate and citrate concentrations and their external efflux to confer higher Al resistance.

Cadmium induction of lipid peroxidation and effects on root tip cells and antioxidant enzyme activities in Vicia faba L.

PubMed

Zhang, Shanshan; Zhang, Huimin; Qin, Rong; Jiang, Wusheng; Liu, Donghua

2009-10-01

The effects of different concentrations (1-50 microM) of Cd on root growth, cell division and nucleoli in root tip cells, protective enzyme activities and lipid peroxidation in Vicia faba were investigated in order to better understand the processes of Cd-induced senescence. The results indicated that lower concentration of Cd (1 microM) had no obviously influence on the root growth during 24-48 h treatment, but higher concentrations (5-50 microM) inhibited significantly after 48 and 72 h. The mitotic index decreased with increasing of Cd concentration and duration of treatment except for the group exposed to 1 microM Cd. Cd induced c-mitosis, chromosome bridges, chromosome stickiness and lagging chromosomes. The rate of aberrant dividing cells increased with prolonging duration of treatment and increasing of Cd concentration. On nucleolus, some particulates containing the argyrophilic proteins were extruded from the nucleus into the cytoplasm in the cells stressed by Cd and some were scattered in the nucleus. After the treatment with Cd (10 microM Cd, 48 h), the nucleolus did not disaggregate normally and still remain its characteristic structure during metaphase and the particles of similar silver-stained materials were localized on chromosomes. In leaves, Catalase (CAT) activity declined but Peroxidase (POD) activity increased with increasing of the duration of treatment. In roots, CAT activity increased with increasing of the duration of treatment, POD activity increased during early days and then declined. Superoxide dismutase (SOD) activity showed an upward trend with increasing of the duration of treatment after 3 and 6 days, then declined both in leaves and roots (9 days). SOD and POD had highest activities at 50 microM Cd in leaves. CAT activity was lowest at 50 microM Cd. Malondialdehyde (MDA) content increased with the increasing of Cd concentrations and duration of treatment in leaves. In roots, MDA content showed an upward trend with increasing of the duration of treatment at early time and then declined.

Uranium fate in wetland mesocosms: Effects of plants at two iron loadings with different pH values

EPA Science Inventory

Small-scale continuous flow wetland mesocosms (~0.8 L) were used to evaluate how plant roots under different iron loadings affect uranium (U) mobility. When significant concentrations of ferrous iron (Fe) were present at circumneutral pH values, U concentrations in root exposed ...

Elevated nicotianamine levels in Arabidopsis halleri roots play a key role in zinc hyperaccumulation.

PubMed

Deinlein, Ulrich; Weber, Michael; Schmidt, Holger; Rensch, Stefan; Trampczynska, Aleksandra; Hansen, Thomas H; Husted, Søren; Schjoerring, Jan K; Talke, Ina N; Krämer, Ute; Clemens, Stephan

2012-02-01

Zn deficiency is among the leading health risk factors in developing countries. Breeding of Zn-enriched crops is expected to be facilitated by molecular dissection of plant Zn hyperaccumulation (i.e., the ability of certain plants to accumulate Zn to levels >100-fold higher than normal plants). The model hyperaccumulators Arabidopsis halleri and Noccaea caerulescens share elevated nicotianamine synthase (NAS) expression relative to nonaccumulators among a core of alterations in metal homeostasis. Suppression of Ah-NAS2 by RNA interference (RNAi) resulted in strongly reduced root nicotianamine (NA) accumulation and a concomitant decrease in root-to-shoot translocation of Zn. Speciation analysis by size-exclusion chromatography coupled to inductively coupled plasma mass spectrometry showed that the dominating Zn ligands in roots were NA and thiols. In NAS2-RNAi plants, a marked increase in Zn-thiol species was observed. Wild-type A. halleri plants cultivated on their native soil showed elemental profiles very similar to those found in field samples. Leaf Zn concentrations in NAS2-RNAi lines, however, did not reach the Zn hyperaccumulation threshold. Leaf Cd accumulation was also significantly reduced. These results demonstrate a role for NAS2 in Zn hyperaccumulation also under near-natural conditions. We propose that NA forms complexes with Zn(II) in root cells and facilitates symplastic passage of Zn(II) toward the xylem.

Elevated Nicotianamine Levels in Arabidopsis halleri Roots Play a Key Role in Zinc Hyperaccumulation[W

PubMed Central

Deinlein, Ulrich; Weber, Michael; Schmidt, Holger; Rensch, Stefan; Trampczynska, Aleksandra; Hansen, Thomas H.; Husted, Søren; Schjoerring, Jan K.; Talke, Ina N.; Krämer, Ute; Clemens, Stephan

2012-01-01

Zn deficiency is among the leading health risk factors in developing countries. Breeding of Zn-enriched crops is expected to be facilitated by molecular dissection of plant Zn hyperaccumulation (i.e., the ability of certain plants to accumulate Zn to levels >100-fold higher than normal plants). The model hyperaccumulators Arabidopsis halleri and Noccaea caerulescens share elevated nicotianamine synthase (NAS) expression relative to nonaccumulators among a core of alterations in metal homeostasis. Suppression of Ah-NAS2 by RNA interference (RNAi) resulted in strongly reduced root nicotianamine (NA) accumulation and a concomitant decrease in root-to-shoot translocation of Zn. Speciation analysis by size-exclusion chromatography coupled to inductively coupled plasma mass spectrometry showed that the dominating Zn ligands in roots were NA and thiols. In NAS2-RNAi plants, a marked increase in Zn-thiol species was observed. Wild-type A. halleri plants cultivated on their native soil showed elemental profiles very similar to those found in field samples. Leaf Zn concentrations in NAS2-RNAi lines, however, did not reach the Zn hyperaccumulation threshold. Leaf Cd accumulation was also significantly reduced. These results demonstrate a role for NAS2 in Zn hyperaccumulation also under near-natural conditions. We propose that NA forms complexes with Zn(II) in root cells and facilitates symplastic passage of Zn(II) toward the xylem. PMID:22374395

Correlates of root caries experience in middle-aged and older adults in the Northwest Practice-based REsearch Collaborative in Evidence-based DENTistry research network.

PubMed

Chi, Donald L; Berg, Joel H; Kim, Amy S; Scott, JoAnna

2013-05-01

The authors examined the correlates of root caries experience for middle-aged adults (aged 45-64 years) and older adults (65 years and older) to test the hypothesis that the factors related to root caries are different for middle-aged adults than they are for older adults. The authors conducted an observational cross-sectional study that focused on adult patients aged 45 to 97 years recruited from the Northwest Practice-based REsearch Collaborative in Evidence-based DENTistry research network (N = 775). The outcome variable was any root caries experience (no/yes). The authors hypothesized that sociodemographic, intra- oral and behavioral factors were root caries correlates. The authors used Poisson regression models to generate overall and age-stratified prevalence ratios (PRs) of root caries, and they used generalized estimating equations to account for practice-level clustering of participants. A total of 19.6 percent of adults had any root caries. A dentist's assessment that the patient was at high risk of developing any caries was associated with greater prevalence of root caries experience in both middle-aged adults (PR, 2.70; 95 percent confidence interval [CI], 1.63-4.46) and older adults (PR, 1.87; 95 percent CI, 1.19-2.95). The following factors were associated significantly with increased root caries prevalence but only for middle-aged adults: male sex (P = .02), self-reported dry mouth (P < .001), exposed roots (P = .03) and increased frequency of eating or drinking between meals (P = .03). No other covariates were related to root caries experience for older adults. Within a practice-based research network, the factors associated with root caries experience were different for middle-aged adults than they were for older adults. Research is needed to identify relevant root caries correlates for adults 65 years and older. Practical Implications. Interventions aimed at preventing root caries are likely to be different for middle-aged adults than for older adults. Dentists should use root caries prevention programs that address appropriate aged-based risk factors.

Root cultures of Hypericum perforatum subsp. angustifolium elicited with chitosan and production of xanthone-rich extracts with antifungal activity.

PubMed

Tocci, Noemi; Simonetti, Giovanna; D'Auria, Felicia Diodata; Panella, Simona; Palamara, Anna Teresa; Valletta, Alessio; Pasqua, Gabriella

2011-08-01

Hypericum perforatum is a well-known medicinal plant which contains a wide variety of metabolites, including xanthones, which have a wide range of biological properties, including antifungal activity. In the present study, we evaluated the capability of roots regenerated from calli of H. perforatum subsp. angustifolium to produce xanthones. Root biomass was positively correlated with the indole-3-butyric acid concentration, whereas a concentration of 1 mg l(-1) was the most suitable for the development of roots. High auxin concentrations also inhibited xanthone accumulation. Xanthones were produced in large amounts, with a very stable trend throughout the culture period. When the roots were treated with chitosan, the xanthone content dramatically increased, peaking after 7 days. Chitosan also induced a release of these metabolites into the culture. The maximum accumulation (14.26 ± 0.62 mg g(-1) dry weight [DW]) and release (2.64 ± 0.13 mg g(-1) DW) of xanthones were recorded 7 days after treatment. The most represented xanthones were isolated, purified, and spectroscopically characterized. Antifungal activity of the total root extracts was tested against a broad panel of human fungal pathogen strains (30 Candida species, 12 Cryptococcus neoformans, and 16 dermatophytes); this activity significantly increased when using chitosan. Extracts obtained after 7 days of chitosan treatment showed high antifungal activity (mean minimum inhibitory concentration of 83.4, 39.1, and 114 μg ml(-1) against Candida spp., C. neoformans, and dermatophytes, respectively). Our results suggest that root cultures can be considered as a potential tool for large-scale production of extracts with stable quantities of xanthones.

Improved urban stormwater treatment and pollutant removal pathways in amended wet detention ponds.

PubMed

Istenič, Darja; Arias, Carlos A; Vollertsen, Jes; Nielsen, Asbjørn H; Wium-Andersen, Tove; Hvitved-Jacobsen, Thorkild; Brix, Hans

2012-01-01

Dissolved and colloidal bound pollutants are generally poorly removed from stormwater in wet detention ponds. These fractions are, however, the most bio-available, and therefore three wet detention ponds were amended with planted sand filters, sorption filters and addition of precipitation chemicals to enhance the removal of dissolved pollutants and pollutants associated with fine particles and colloids. The three systems treated runoff from industrial, residential and combined (residential and highway) catchments and had permanent volumes of 1,990, 6,900 and 2,680 m(3), respectively. The treatment performance of the ponds for elimination of total suspended solids (TSS), total nitrogen (Tot-N), total phosphorous (Tot-P), PO(4)-P, Pb, Zn, Cd, Ni, Cr, Cu, Hg were within the range typically reported for wet detention ponds, but the concentrations of most of the pollutants were efficiently reduced by the planted sand filters at the outlets. The sorption filters contributed to further decrease the concentration of PO(4)-P from 0.04 ± 0.05 to 0.01 ± 0.01 mg L(-1) and were also efficient in removing heavy metals. Dosing of iron sulphate to enrich the bottom sediment with iron and dosing of aluminium salts to the inlet water resulted in less growth of phytoplankton, but treatment performance was not significantly affected. Heavy metals (Pb, Zn, Cd, Ni, Cr and Cu) accumulated in the sediment of the ponds. The concentrations of Zn, Ni, Cu and Pb in the roots of the wetland plants were generally correlated to the concentrations in the sediments. Among 13 plant species investigated, Rumex hydrolapathum accumulated the highest concentrations of heavy metals in the roots (Concentration Factor (CF) of 4.5 and 5.9 for Zn and Ni, respectively) and Iris pseudacorus the lowest (CF < 1). The translocation of heavy metals from roots to the aboveground tissues of plants was low. Therefore the potential transfer of heavy metals from the metal-enriched sediment to the surrounding ecosystem via plant uptake and translocation is negligible.

Arbuscular mycorrhizal fungi and plant growth-promoting pseudomonads increases anthocyanin concentration in strawberry fruits (Fragaria x ananassa var. Selva) in conditions of reduced fertilization.

PubMed

Lingua, Guido; Bona, Elisa; Manassero, Paola; Marsano, Francesco; Todeschini, Valeria; Cantamessa, Simone; Copetta, Andrea; D'Agostino, Giovanni; Gamalero, Elisa; Berta, Graziella

2013-08-06

Anthocyanins are a group of common phenolic compounds in plants. They are mainly detected in flowers and fruits, are believed to play different important roles such as in the attraction of animals and seed dispersal, and also in the increase of the antioxidant response in tissues directly or indirectly affected by biotic or abiotic stress factors. As a major group of secondary metabolites in plants commonly consumed as food, they are of importance in both the food industry and human nutrition. It is known that arbuscular mycorrhizal (AM) fungi can influence the plant secondary metabolic pathways such as the synthesis of essential oils in aromatic plants, of secondary metabolites in roots, and increase flavonoid concentration. Plant Growth-Promoting Bacteria (PGPB) are able to increase plant growth, improving plant nutrition and supporting plant development under natural or stressed conditions. Various studies confirmed that a number of bacterial species living on and inside the root system are beneficial for plant growth, yield and crop quality. In this work it is shown that inoculation with AM fungi and/or with selected and tested Pseudomonas strains, under conditions of reduced fertilization, increases anthocyanin concentration in the fruits of strawberry.

Arbuscular Mycorrhizal Fungi and Plant Growth-Promoting Pseudomonads Increases Anthocyanin Concentration in Strawberry Fruits (Fragaria x ananassa var. Selva) in Conditions of Reduced Fertilization

PubMed Central

Lingua, Guido; Bona, Elisa; Manassero, Paola; Marsano, Francesco; Todeschini, Valeria; Cantamessa, Simone; Copetta, Andrea; D’Agostino, Giovanni; Gamalero, Elisa; Berta, Graziella

2013-01-01

Anthocyanins are a group of common phenolic compounds in plants. They are mainly detected in flowers and fruits, are believed to play different important roles such as in the attraction of animals and seed dispersal, and also in the increase of the antioxidant response in tissues directly or indirectly affected by biotic or abiotic stress factors. As a major group of secondary metabolites in plants commonly consumed as food, they are of importance in both the food industry and human nutrition. It is known that arbuscular mycorrhizal (AM) fungi can influence the plant secondary metabolic pathways such as the synthesis of essential oils in aromatic plants, of secondary metabolites in roots, and increase flavonoid concentration. Plant Growth-Promoting Bacteria (PGPB) are able to increase plant growth, improving plant nutrition and supporting plant development under natural or stressed conditions. Various studies confirmed that a number of bacterial species living on and inside the root system are beneficial for plant growth, yield and crop quality. In this work it is shown that inoculation with AM fungi and/or with selected and tested Pseudomonas strains, under conditions of reduced fertilization, increases anthocyanin concentration in the fruits of strawberry. PMID:23924942

Lead accumulation by jabon seedling (Anthocephalus cadamba) on tailing media with application of compost and arbuscular mycorrhizal fungi

NASA Astrophysics Data System (ADS)

Setyaningsih, L.; Setiadi, Y.; Budi, S. W.; Hamim; Sopandie, D.

2017-03-01

Lead (Pb) is one of the dangerous heavy metal contained in tailing that needs remediation activity. This study aimed to investigate the potency of jabon to take up and accumulate lead in its tissue by the application of compost and arbuscular mycorrhiza fungus (AMF) on pot observation. In Pb-containing tailing media, the average levels of Pb in roots seedling was 50% greater as compared to the levels of Pb in the stem and leaves of seedlings. Application of compost in tailings media significantly increased (p ≤ 0.5) the average levels of Pb in the roots and stems, but decreased Pb levels in leaves. Applications AMF significantly decreased (p ≤ 0.5) the average levels of Pb in the roots, stem and leaves of seedlings by approximately 18-33%. The combination applications of compost and AMF significantly (p ≤ 0.5) increased the level of Pb in the roots, stems and leaves of seedlings at 6, 16 and 27 fold respectively than that in control plant (without compost and AMF). After 12 weeks exposure, lead bioconcentration factor varied from 0.1-1.6 in seedling tissue with transport factor varied from 0.1-1.0. The application of active compost and AMF increased 1-15 fold lead accumulation from control, and the biggest accumulation was 452.9 x10-2 mg/plant with Pb concentration of 1.5 mM. Active compost and AMF application supported jabon seedling to act as lead phytostabilizer and to remove lead from the tailing to the above part of the plant.

Uptake and distribution of bisphenol A and nonylphenol in vegetable crops irrigated with reclaimed water.

PubMed

Lu, Jian; Wu, Jun; Stoffella, Peter J; Wilson, P Chris

2015-01-01

The potential uptake and distribution of bisphenol A (BPA) and nonylphenol (NP) (from reclaimed irrigation water) in edible crops was investigated. BPA and NP were spiked into simulated reclaimed water at environmentally relevant concentrations. Two crops (lettuce, Lactuca sativa and tomato, Lycopersicon esculentum) were grown hydroponically in a greenhouse using the spiked irrigation water under two irrigation exposure scenarios (overhead foliar exposure and subsurface root exposure). BPA concentrations in tomato fruit were 26.6 ± 5.8 (root exposure) and 18.3 ± 3.5 (foliar exposure) μg kg(-1), while concentrations in lettuce leaves were 80.6 ± 23.1 (root exposure) and 128.9 ± 17.4 (foliar exposure) μg kg(-1). NP concentrations in tomato fruit were 46.1 ± 6.6 (root exposure) and 24.6 ± 6.4 (foliar exposure) μg kg(-1), while concentrations in lettuce leaves were 144.1 ± 9.2 (root exposure) and 195.0 ± 16.9 (foliar exposure) μg kg(-1). BPA was relatively mobile in lettuce plants regardless of exposure route. Limited mobility was observed for NP in both crops and BPA in tomatoes. The estimated daily intake of BPA and NP through consumption of vegetables irrigated with reclaimed water ranged from 8.9-62.9 to 11.9-95.1 μg, respectively, depending on the exposure route. Copyright © 2014 Elsevier B.V. All rights reserved.

Volatiles emitted by Bacillus sp. BCT9 act as growth modulating agents on Lactuca sativa seedlings.

PubMed

Fincheira, Paola; Parra, Leonardo; Mutis, Ana; Parada, Maribel; Quiroz, Andrés

2017-10-01

Chemical products are applied during horticulture to increase food production, but the environmental problems resulting from these applications have led to a search for more sustainable products. Volatile organic compounds (VOCs) demonstrating plant growth promoter (PGP) activity released by bacterial species have emerged as alternatives, but their effects on Lactuca sativa growth are unknown. In this study, VOCs released by Bacillus sp. BCT9 cultures grown in different media (Methyl Red & Voges Proskauer, Murashige & Skoog and nutrient media) at concentrations of 0.1, 0.2, 0.5 and 0.7 (measured as the absorbance, λ=600nm) were tested to evaluate their activity as growth inducers of L. sativa after 10days of exposure. Lower concentrations of BCT9 increased root length, and higher concentrations induced shoot length and lateral root length. The dry weight and number of lateral roots increased similarly, independent of concentration, for VOCs produced in all culture media. BCT9 cultures grown in Methyl Red & Voges Proskauer medium as bioactive compounds with or without lanolin. These VOCs increased shoot length, root length and dry weight at low concentrations, independent of the presence of lanolin. Lateral root length increased with the application of 2-nonanone (50ppm) and 2-undecanone (0.05ppm). Based on these results, the use of bioactive volatiles as growth inducers of horticultural species represents an alternative or complementary strategy. Copyright © 2017 Elsevier GmbH. All rights reserved.

Sorghum Roots are Inefficient in Uptake of EDTA-chelated Lead

PubMed Central

Xu, Yong; Yamaji, Naoki; Shen, Renfang; Ma, Jian Feng

2007-01-01

Background and Aims Ethylene diamine tetraacetic acid (EDTA)-assisted phytoremediation has been developed to clean up lead (Pb)-contaminated soil; however, the mechanism responsible for the uptake of EDTA–Pb complex is not well understood. In this study, the accumulation process of Pb from EDTA–Pb is characterized in comparison to ionic Pb [Pb(NO3)2] in sorghum (Sorghum bicolor). Methods Sorghum seedlings were exposed to a 0·5 mm CaCl2 (pH 5·0) solution containing 0, 1 mm Pb(NO3)2 or EDTA–Pb complexes at a molar ratio of 1:0·5, 1:1, 1:2 and 1:4 (Pb:EDTA). The root elongation of sorghum at different ratios of Pb:EDTA was measured. Xylem sap was collected after the stem was severed at different times. The concentration of Pb in the shoots and roots were determined by an atomic absorption spectrometer. In addition, the roots were stained with Fluostain I for observation of the root structure. Key Results Lead accumulation in the shoots of the plants exposed to EDTA–Pb at 1:1 ratio was only one-fifth of that exposed to ionic Pb at the same concentration. Lead accumulation decreased when transpiration was suppressed. The concentration of Pb in the xylem sap from the EDTA–Pb-treated plants was about 1/25 000 of that in the external solution. Root elongation was severely inhibited by ionic Pb, but not by EDTA–Pb at a 1:1 ratio. Root staining showed that a physiological barrier was damaged in the roots exposed to ionic Pb, but not in the roots exposed to EDTA–Pb. Conclusions All these results suggest that sorghum roots are inefficient in uptake of EDTA-chelated Pb and that enhanced Pb accumulation from ionic Pb was attributed to the damaged structure of the roots. PMID:17452378

In vitro propagation, encapsulation, and genetic fidelity analysis of Terminalia arjuna: a cardioprotective medicinal tree.

PubMed

Gupta, Amit K; Harish; Rai, Manoj K; Phulwaria, Mahendra; Agarwal, Tanvi; Shekhawat, N S

2014-07-01

The present study described an improved and reproducible in vitro regeneration system for Terminalia arjuna using nodal segment explants obtained from a mature plant. Shoot tips excised from in vitro proliferated shoots were encapsulated in 3 % sodium alginate and 100 mM CaCl2[Symbol: see text]2H2O for the development of synthetic seeds which may be applicable in short-term storage and germplasm exchange of elite genotype. Shoot multiplication was significantly influenced by a number of factors, namely types and concentrations of plant growth regulators, medium composition, repeated transfer of mother explants, subculturing of in vitro regenerated shoot clumps, agar concentrations, and temperature. Maximum numbers of shoots (16.50 ± 3.67) were observed on modified Murashige and Skoog (MMS) medium containing 0.5 mg l(-1) of benzylaminopurine (BAP) and 0.1 mg l(-1) of naphthalene acetic acid (NAA). To shortening the regeneration pathway, rooting of micropropagated shoots under in vitro condition was excluded and an experiment on ex vitro rooting was conducted and it was observed that the highest percentage of shoots rooted ex vitro when treated with indole-3-butyric acid (IBA, 250 mg l(-1)) + 2-naphthoxy acetic acid (NOA, 250 mg l(-1)) for 5 min. The well-developed ex vitro rooted shoots were acclimatized successfully in soilrite under greenhouse conditions with 80 % survival of plants. Randomly amplified polymorphic DNA (RAPD) analysis confirmed that all the regenerated plants were genetically identical to the mother plant, suggesting the absence of detectable genetic variation in the regenerated plantlets. To the best of our knowledge, this is the first report on synthetic seed production as well as ex vitro rooting and genetic fidelity assessment of micropropagated shoots of T. arjuna.

Influence of ozone on cold acclimation in sugar maple seedlings.

PubMed

Bertrand, Annick; Robitaille, Gilles; Nadeau, Paul; Castonguay, Yves

1999-07-01

During summer 1994, sugar maple (Acer saccharum Marsh.) seedlings were grown in open-top chambers supplied with air containing near ambient ozone concentration (control, low O(3)) or three times the ambient ozone concentration (high O(3)). The rate of CO(2) assimilation was significantly reduced by chronic exposure to a high concentration of ozone during the summer. During fall, seedlings were removed from the open-top chambers and acclimated to cold under natural conditions. In both species during cold acclimation, the starch concentration decreased, whereas the sucrose concentration increased. There was no treatment effect on the freezing tolerance of roots, even though roots in the high-O(3) treatment accumulated higher concentrations of the cryoprotective oligosaccharides raffinose and stachyose than control roots. Cold acclimation occurred earlier and stachyose concentration of stems was higher in high-O(3)-treated seedlings than in low-O(3)-treated seedlings. Cold acclimation was associated with an earlier accumulation of ABA in the xylem sap of high-O(3)-treated seedlings compared with low-O(3)-treated seedlings.

DNA analysis of soil extracts can be used to investigate fine root depth distribution of trees

PubMed Central

Bithell, Sean L.; Tran-Nguyen, Lucy T. T.; Hearnden, Mark N.; Hartley, Diana M.

2015-01-01

Understanding the root distribution of trees by soil coring is time-consuming as it requires the separation of roots from soil and classification of roots into particular size classes. This labour-intensive process can limit sample throughput and therefore sampling intensity. We investigated the use of quantitative polymerase chain reaction (qPCR) on soil DNA extractions to determine live fine root DNA density (RDD, mg DNA m−2) for mango (Mangifera indica) trees. The specificity of the qPCR was tested against DNA extracted from 10 mango cultivars and 14 weed species. All mango cultivars and no weeds were detected. Mango DNA was successfully quantified from control soil spiked with mango roots and weed species. The DNA yield of mango root sections stored in moist soil at 23–28 °C declined after 15 days to low concentrations as roots decayed, indicating that dead root materials in moist soil would not cause false-positive results. To separate large roots from samples, a root separation method for field samples was used to target the root fragments remaining in sieved (minimum 2 mm aperture) soil for RDD comparisons. Using this method we compared the seasonal RDD values of fine roots for five mango rootstock cultivars in a field trial. The mean cultivar DNA yields by depth from root fragments in the sieved soil samples had the strongest relationship (adjusted multiple R2 = 0.9307, P < 0.001) with the dry matter (g m−2) of fine (diameter <0.64 mm) roots removed from the soil by sieving. This method provides a species-specific and rapid means of comparing the distribution and concentration of live fine roots of trees in orchards using soil samples up to 500 g. PMID:25552675

Arsenic accumulation and speciation in maize as affected by inoculation with arbuscular mycorrhizal fungus Glomus mosseae.

PubMed

Yu, Yang; Zhang, Shuzhen; Huang, Honglin; Luo, Lei; Wen, Bei

2009-05-13

Effects of inoculation with arbuscular mycorrhizal (AM) fungus (Glomus mosseae) on arsenic (As) accumulation and speciation in maize were investigated by using As spiked soil at the application levels of 0, 25, 50, and 100 mg kg(-1). Inorganic As was the major species in plants, and mycorrhizal inoculation generally decreased concentrations of arsenite [As(III)] in maize roots and concentrations of As(III) and arsenate [As(V)] in the shoots. Dimethylarsenic acid (DMA) concentrations (detected in every plant sample) were higher in maize shoots for mycorrhizal than for nonmycorrhizal treatment, but no significant differences were observed for roots. Monomethylarsenic acid (MMA) was only detected in roots with mycorrhizal colonization. The uptake of As(V) was much lower by excised mycorrhizal than nonmycorrhizal roots, and the differences for the uptake of As(III) were negligible. Arsenate reductase (AR) activity was detected in maize roots, and it was reduced with mycorrhizal inoculation. Activities of peroxidase (POD) and superoxide dismutase (SOD) were detected in both maize shoots and roots, and they were suppressed by mycorrhizal inoculation. AM inoculation inhibited the uptake of As(V) and its reduction to As(III), reducing oxidation stress and thereby alleviating As toxicity to the host plant.

Inhibition of Ageratina adenophora on spore germination and gametophyte development of Macrothelypteris torresiana.

PubMed

Zhang, Kai-Mei; Shi, Lei; Jiang, Chuang-Dao; Li, Zhen-Yu

2008-05-01

Allelopathy of Ageratina adenophora plays an important role in its invasion. However, we have little knowledge of its allelpathic effects on ferns. In Petri dish bioassays, the inhibitory potential of aqueous leachates from roots, stems and leaves of A. adenophora was studied on the spore germination and gametophyte development of Macrothelypteris torresiana. All leachates inhibited the spore germination and growth of the first rhizoid of M. torresiana and inhibitory effects increased with increasing leachate concentrations. Root leachates proved most inhibitory. Gametophyte rhizoids of M. torresiana treated with stem and leaf leachates of A. adenophora were erect, which was similar to those of the control. However, gametophyte rhizoids of M. torresiana treated with root leachates of A. adenophora were erect, but also curving or swollen. Moreover, curving and swollen rhizoids increased with increasing concentrations. As time went by, rhizoids treated with root leachates were not so curved and the swelling almost disappeared. Possible causes are discussed in the present study. The increasing concentrations of leaf leachates also delayed the stages of gametophyte development. With the treatment of root leachates, the delay was more obvious. Thus A. adenophora inhibited the spore germination and gametophyte development of M. torresiana and the root leachates were most inhibitory.

Physiological and biochemical responses of Salix integra Thunb. under copper stress as affected by soil flooding.

PubMed

Cao, Yini; Ma, Chuanxin; Chen, Guangcai; Zhang, Jianfeng; Xing, Baoshan

2017-06-01

To explore the joint effect of copper (Cu) and flooding on Salix integra Thunb. (S. integra), the physiological and biochemical parameters of the seedlings grown in Cu amended soil (50, 150, 450 mg kg -1 ) with or without the flooding for 60 days were evaluated. The results suggested that the flooding significantly inhibited the root growth in terms of root length and root tips. The Cu exposures of 50 and 150 mg kg -1 notably enhanced the root growth as compared to the control. Majority of Cu was accumulated in S. integra roots, while flooding significantly reduced the Cu content, except the 150 mg kg -1 Cu treatment, but the iron (Fe) and manganese (Mn) content on the root surface were both markedly increased relative to non-flooded control. The malonaldehyde (MDA) and glutathione (GSH) contents in leaves showed a dose-response upon Cu exposure. Soil flooding enhanced the GSH level, which displayed 4.50-49.59% increases compared to its respective non-flooded treatment, while no difference was evident on MDA contents between the flooding and the non-flooded treatments. Both superoxide dismutase (SOD) and peroxidase (POD) activities were boosted while the catalase (CAT) was suppressed with increasing Cu exposure dose, and soil flooding reduced the POD and CAT activities. The elevated Cu level caused the evident increases of root calcium (Ca), potassium (K), and sulfur (S) concentrations and decreases of root phosphorus (P), sodium (Na), and zinc (Zn) concentrations. Soil flooding increased the concentrations of Fe, S, Na, Ca, and magnesium (Mg) in S. integra root. Taken together, our results suggested S. integra has high tolerance to the joint stress from Cu and flooding. Copyright © 2017 Elsevier Ltd. All rights reserved.

Absorption Kinetics and Subcellular Fractionation of Zinc in Winter Wheat in Response to Nitrogen Supply.

PubMed

Nie, Zhaojun; Zhao, Peng; Wang, Jia; Li, Jinfeng; Liu, Hongen

2017-01-01

Nitrogen (N) is critical for zinc (Zn) absorption into plant roots; this in turn allows for Zn accumulation and biofortification of grain in winter wheat ( Triticum aestivum L.), an important food crop. However, little is known about root morphology and subcellular Zn distribution in response to N treatment at different levels of Zn supply. In this study, two nutrient solution culture experiments were conducted to examine Zn accumulation, Zn absorption kinetics, root morphology, and Zn subcellular distribution in wheat seedlings pre-cultured with different N concentrations. The results showed positive correlations between N and Zn concentrations, and N and Zn accumulation, respectively. The findings suggested that an increase in N supply enhanced root absorption and the root-to-shoot transport of Zn. Nitrogen combined with the high Zn (Zn 10 ) treatment increased the Zn concentration and consequently its accumulation in both shoots and roots. The maximum influx rate ( V max ), root length, surface area, and volume of 14-d-old seedlings, and root growth from 7 to 14 d in the medium N (N 7.5 ) treatment were higher, but the Michaelis constant ( K m ) and minimum equilibrium concentrations ( C min ) in this treatment were lower than those in the low (N 0.05 ) and high (N 15 ) N treatments, when Zn was supplied at a high level (Zn 10 ). Meanwhile, there were no pronounced differences in the above root traits between the N 0.05 Zn 0 and N 7.5 Zn 10 treatments. An increase in N supply decreased Zn in cell walls and cell organelles, while it increased Zn in the root soluble fraction. In leaves, an increase in N supply significantly decreased Zn in cell walls and the soluble fraction, while it increased Zn in cell organelles under Zn deficiency, but increased Zn distribution in the soluble fraction under medium and high Zn treatments. Therefore, a combination of medium N and high Zn treatments enhanced Zn absorption, apparently by enhancing Zn membrane transport and stimulating root development in winter wheat. An increase in N supply was beneficial in terms of achieving a balanced distribution of Zn subcellular fractions, thus enhancing Zn translocation to shoots, while maintaining normal metabolism.

Effect of feeding cassava (Manihot esculenta Crantz) root meal on growth performance, hydrocyanide intake and haematological parameters of broiler chicks.

PubMed

Akapo, Abiola Olajetemi; Oso, Abimbola Oladele; Bamgbose, Adeyemi Mustapha; Sanwo, Kehinde A; Jegede, Adebayo Vincent; Sobayo, Richard Abayomi; Idowu, Olusegun Mark; Fan, Juexin; Li, Lili; Olorunsola, Rotimi A

2014-10-01

The effect of feeding cassava root meal on growth performance, hydrocyanide intake, haematological indices and serum thiocyanate concentration of broiler chicks was investigated using 300-day-old male broilers. There were five dietary treatments arranged in a 2 × 2 + 1 factorial arrangement of two processing methods of cassava root (peeled and unpeeled) included at two levels (100 and 200 g/kg) plus a control diet (maize-based diet, containing no cassava root). Each treatment was replicated six times with ten birds per replicate. The feeding trial lasted for 28 days. Control-fed birds had the highest overall (P < 0.01) final liveweight and weight gain, least (P < 0.05) hydrocyanide (HCN) intake and best (P < 0.05) feed-to-gain ratio. Chicks fed with control and diet containing 100 g/kg peeled cassava root meal (PCRM) had the least (P < 0.05) feed cost per weight gain. Chicks fed with diet containing 100 g/kg cassava root meal had higher (P < 0.05) final liveweight and weight gain and reduced (P < 0.05) HCN intake than chicks fed with diet containing 200 g/kg cassava root meal. Dietary inclusion of peeled cassava root meal (PCRM) for broiler chicks resulted in increased final liveweight (P < 0.05), weight gain (P < 0.01) and feed intake (P < 0.01) when compared with birds fed with diet containing unpeeled cassava root meal (UCRM). The least (P < 0.01) final liveweight and weight gain and worst (P < 0.05) feed-to-gain ratio were obtained with chicks fed with diet containing 200 g/kg UCRM. Increased dietary inclusion levels of cassava root resulted in significant increase (P < 0.05) in white blood cell (WBC) count, heterophil count and serum thiocyanate concentration. In comparison with chicks fed with diet containing UCRM, dietary inclusion of PCRM resulted in increased (P < 0.05) red blood cell (RBC) count and haemoglobin (Hb) concentration and reduced (P < 0.05) white blood cell (WBC) count and serum thiocyanate concentration. Although inclusion of 100 g/kg PCRM showed some economic sense, dietary inclusion of either peeled or unpeeled cassava root poses a threat on growth and health status of broiler chicks.

Absorption Kinetics and Subcellular Fractionation of Zinc in Winter Wheat in Response to Nitrogen Supply

PubMed Central

Nie, Zhaojun; Zhao, Peng; Wang, Jia; Li, Jinfeng; Liu, Hongen

2017-01-01

Nitrogen (N) is critical for zinc (Zn) absorption into plant roots; this in turn allows for Zn accumulation and biofortification of grain in winter wheat (Triticum aestivum L.), an important food crop. However, little is known about root morphology and subcellular Zn distribution in response to N treatment at different levels of Zn supply. In this study, two nutrient solution culture experiments were conducted to examine Zn accumulation, Zn absorption kinetics, root morphology, and Zn subcellular distribution in wheat seedlings pre-cultured with different N concentrations. The results showed positive correlations between N and Zn concentrations, and N and Zn accumulation, respectively. The findings suggested that an increase in N supply enhanced root absorption and the root-to-shoot transport of Zn. Nitrogen combined with the high Zn (Zn10) treatment increased the Zn concentration and consequently its accumulation in both shoots and roots. The maximum influx rate (Vmax), root length, surface area, and volume of 14-d-old seedlings, and root growth from 7 to 14 d in the medium N (N7.5) treatment were higher, but the Michaelis constant (Km) and minimum equilibrium concentrations (Cmin) in this treatment were lower than those in the low (N0.05) and high (N15) N treatments, when Zn was supplied at a high level (Zn10). Meanwhile, there were no pronounced differences in the above root traits between the N0.05Zn0 and N7.5Zn10 treatments. An increase in N supply decreased Zn in cell walls and cell organelles, while it increased Zn in the root soluble fraction. In leaves, an increase in N supply significantly decreased Zn in cell walls and the soluble fraction, while it increased Zn in cell organelles under Zn deficiency, but increased Zn distribution in the soluble fraction under medium and high Zn treatments. Therefore, a combination of medium N and high Zn treatments enhanced Zn absorption, apparently by enhancing Zn membrane transport and stimulating root development in winter wheat. An increase in N supply was beneficial in terms of achieving a balanced distribution of Zn subcellular fractions, thus enhancing Zn translocation to shoots, while maintaining normal metabolism. PMID:28868060

Rewetting Rate of Dry Rhizosphere Limited by Mucilage Viscosity and Mucilage Hydrophobicity

NASA Astrophysics Data System (ADS)

Reeder, Stacey; Zarebanadkouki, Mohsen; Kroener, Eva; Ahmed, Mutez Ali; Carminati, Andrea; Kostka, Stanley

2015-04-01

During root water uptake from dry soils, the highly nonlinear relation between hydraulic conductivity and water content as well as the radial root geometry result in steep water potential gradients close to the root surface. The hydraulic properties of the rhizosphere - the interface between root and soil - are one of the most important and least understood components in controlling root water uptake. Previous research using young lupine plants revealed that after irrigation it took 1-2 days for the water content of the dry rhizosphere to increase. How can this delay be explained? Our hypotheses are that: a) mucilage - a polymeric plant exudate - alters rhizosphere hydraulic properties, b) its hydrophobic moieties make the rhizosphere water repellent when dry, c) mucilage is a highly viscous, gelatinous material, the dryer it gets the more viscous it becomes, d) mucilage viscosity reduces rhizosphere hydraulic conductivity. To test our hypotheses we used mucilage extracted from chia seed as an analogue for root mucilage. We measured: 1) the contact angle between water and pure dry and wet mucilage, dry soil treated with various concentrations of mucilage, 2) mucilage viscosity as function of concentration and shear rate, 3) saturated hydraulic conductivity as function of mucilage concentration, 4) swelling of dry mucilage in water. Finally, to mimic flow of water across the rhizosphere, we measured the capillary rise in soils treated with different mucilage concentrations. The results showed that: 1) dry mucilage has a contact angle > 90° while it loses its water repellency when it gets wet, 2) viscosity and saturated hydraulic conductivity can change several orders of magnitude with a small change in mucilage concentration, 3) 1g of dry mucilage absorbs 300g water in its fully swollen state, 4) the swelling rate of mucilage showed an exponential behavior with half time of 5 hours. Capillary rise became slower in soils with higher mucilage concentration, while the final water holding capacity increased with mucilage concentration. We conclude that the slow rewetting of the rhizosphere is initially caused by the high contact angle. As the mucilage swells it occupies the pore space and controls the water flow due to its high viscosity. These studies show the high potential of root exudates to control the rhizosphere water dynamics.

The effects of different sewage sludge amendment rates on the heavy metal bioaccumulation, growth and biomass of cucumbers (Cucumis sativus L.).

PubMed

Eid, Ebrahem M; Alrumman, Sulaiman A; El-Bebany, Ahmed F; Hesham, Abd El-Latif; Taher, Mostafa A; Fawy, Khaled F

2017-07-01

When sewage sludge is incorrectly applied, it may adversely impact agro-system productivity. Thus, this study addresses the reaction of Cucumis sativus L. (cucumber) to different amendment rates (0, 10, 20, 30, 40 and 50 g kg -1 ) of sewage sludge in a greenhouse pot experiment, in which the plant growth, heavy metal uptake and biomass were evaluated. A randomized complete block design with six treatments and six replications was used as the experimental design. The soil electrical conductivity, organic matter and Cr, Fe, Zn and Ni concentrations increased, but the soil pH decreased in response to the sewage sludge applications. As approved by the Council of European Communities, all of the heavy metal concentrations in the sewage sludge were less than the permitted limit for applying sewage sludge to land. Generally, applications of sewage sludge of up to 40 g kg -1 resulted in a considerable increase in all of the morphometric parameters and biomass of cucumbers in contrast to plants grown on the control soil. Nevertheless, the cucumber shoot height; root length; number of leaves, internodes and fruits; leaf area; absolute growth rate and biomass decreased in response to 50 g kg -1 of sewage sludge. All of the heavy metal concentrations (except the Cu, Zn and Ni in the roots, Mn in the fruits and Pb in the stems) in different cucumber tissues increased with increasing sewage sludge application rates. However, all of the heavy metal concentrations (except the Cr and Fe in the roots, Fe in the leaves and Cu in the fruits) were within the normal range and did not reach phytotoxic levels. A characteristic of these cucumbers was that all of the heavy metals had a bioaccumulation factor <1.0. All of the heavy metals (except Cd, Cu and Zn) had translocation factors that were <1.0. As a result, the sewage sludge used in this study could be considered for use as a fertilizer in cucumber production systems in Saudi Arabia and can also serve as a substitute method of sewage sludge disposal. Graphical Abstract The effects of different sewage sludge amendment rates on the heavy metal bioaccumulation, growth and biomass of cucumbers.

Intraspecific variation in fine root respiration and morphology in response to in situ soil nitrogen fertility in a 100-year-old Chamaecyparis obtusa forest.

PubMed

Makita, Naoki; Hirano, Yasuhiro; Sugimoto, Takanobu; Tanikawa, Toko; Ishii, Hiroaki

2015-12-01

Soil N fertility has an effect on belowground C allocation, but the physiological and morphological responses of individual fine root segments to variations in N availability under field conditions are still unclear. In this study, the direction and magnitude of the physiological and morphological function of fine roots in response to variable in situ soil N fertility in a forest site were determined. We measured the specific root respiration (Rr) rate, N concentration and morphology of fine root segments with 1-3 branching orders in a 100-year-old coniferous forest of Chamaecyparis obtusa. Higher soil N fertility induced higher Rr rates, root N concentration, and specific root length (SRL), and lower root tissue density (RTD). In all fertility levels, the Rr rates were significantly correlated positively with root N and SRL and negatively with RTD. The regression slopes of respiration with root N and RTD were significantly higher along the soil N fertility gradient. Although no differences in the slopes of Rr and SRL relationship were found across the levels, there were significant shifts in the intercept along the common slope. These results suggest that a contrasting pattern in intraspecific relationships between specific Rr and N, RTD, and SRL exists among soils with different N fertility. Consequently, substantial increases in soil N fertility would exert positive effects on organ-scale root performance by covarying the Rr, root N, and morphology for their potential nutrient and water uptake.

Individual tree differences confound effects of growth regulators in rooting sugar maple softwood cuttings

Treesearch

John R. Donnelly

1971-01-01

Softwood stem cuttings from three mature sugar maple trees were treated with several types and concentrations of growth regulators. Lack of statistical significance was due to extreme variability in tree response: low levels of auxin stimulated rooting in two study trees, while auxins inhibited rooting in the other tree. It is postulated that variations in rooting...

Diageotropica and lateral rooting, the rest of the story

USDA-ARS?s Scientific Manuscript database

The nature of the control of lateral root initiation has been controversial for 80+ years. A mutant tomato (diageotropica), incapable of producing lateral roots, was first classified as ethylene requiring since exceptionally low concentrations of ethylene, applied to the shoot, stimulated lateral r...

Effects and mechanisms of the combined pollution of lanthanum and acid rain on the root phenotype of soybean seedlings.

PubMed

Sun, Zhaoguo; Wang, Lihong; Zhou, Qing; Huang, Xiaohua

2013-09-01

Rare earth pollution and acid rain pollution are both important environmental issues worldwide. In regions which simultaneously occur, the combined pollution of rare earth and acid rain becomes a new environmental issue, and the relevant research is rarely reported. Accordingly, we investigated the combined effects and mechanisms of lanthanum ion (La(3+)) and acid rain on the root phenotype of soybean seedlings. The combined pollution of low-concentration La(3+) and acid rain exerted deleterious effects on the phenotype and growth of roots, which were aggravated by the combined pollution of high-concentration La(3+) and acid rain. The deleterious effects of the combined pollution were stronger than those of single La(3+) or acid rain pollution. These stronger deleterious effects on the root phenotype and growth of roots were due to the increased disturbance of absorption and utilization of mineral nutrients in roots. Copyright © 2013 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robison, W L; Hamilton, T F; Bogen, K

Inter-plant concentration ratios (IPCR), [Bq g{sup -1} {sup 137}Cs in coral atoll tree food-crops/Bq g{sup -1} {sup 137}Cs in leaves of native plant species whose roots share a common soil volume], can replace transfer factors (TF) to predict {sup 137}Cs concentration in tree food-crops in a contaminated area with an aged source term. The IPCR strategy has significant benefits relative to TF strategy for such purposes in the atoll ecosystem. IPCR strategy applied to specific assessments takes advantage of the fact tree roots naturally integrate 137Cs over large volumes of soil. Root absorption of {sup 137}Cs replaces large-scale, expensive soilmore » sampling schemes to reduce variability in {sup 137}Cs concentration due to inhomogeneous radionuclide distribution. IPCR [drinking-coconut meat (DCM)/Scaevola (SCA) and Tournefortia (TOU) leaves (native trees growing on all atoll islands)] are log normally distributed (LND) with geometric standard deviation (GSD) = 1.85. TF for DCM from Enewetak, Eneu, Rongelap and Bikini Atolls are LND with GSD's of 3.5, 3.0, 2.7, and 2.1, respectively. TF GSD for Rongelap copra coconut meat is 2.5. IPCR of Pandanus fruit to SCA and TOU leaves are LND with GSD = 1.7 while TF GSD is 2.1. Because IPCR variability is much lower than TF variability, relative sampling error of an IPCR field sample mean is up 6- to 10-fold lower than that of a TF sample mean if sample sizes are small (10 to 20). Other IPCR advantages are that plant leaf samples are collected and processed in far less time with much less effort and cost than soil samples.« less

Improving the efficiency of phytoremediation using electrically charged plant and chelating agents.

PubMed

Tahmasbian, Iman; Safari Sinegani, Ali Akbar

2016-02-01

The low efficiency of phytoremediation is a considerable problem that limits the application of this environmentally friendly method on heavy metal-polluted soils. The combination of chelate-assisted phytoextraction and electrokinetic remediation could offer new opportunities to improve the effectiveness of phytoextraction. The current experiment aims to investigate the effects of electrical fields and chelating agents on phytoremediation efficiency. In a pot experiment using mine soil, poultry manure extract (PME), cow manure extract (CME), and ethylenediaminetetraacetic acid (EDTA) were applied to soil as chelating agents (2 g kg(-1)) at the beginning of the flowering stage. A week later, Helianthus annuus (sunflower) was negatively charged by inserting a stainless steel needle with 10 and 30 V DC electricity in the lowest part of the stems for 1 h each day for a 14-day period. At the end of the experiment, the shoot and root dry weight, lead (Pb) concentration in plant organs, translocation factor (TF), metal uptake index (UI), and soil available Pb (diethylene triamine pentaacetic acid (DTPA) extractable) were detected. Results indicated that the application of electrical fields had no significant impact on the shoot and root dry weights, while Pb concentration and UI increased in the 10-V EDTA treatment by 500 % compared to control. There was no significant difference between UI in 30- and 10-V EDTA treatments. Soil available Pb significantly increased in the 30-V treated soil. A positive correlation was observed between the available Pb in soil near the root and Pb concentration in shoot, its TF, and UI. In conclusion, a negatively charged plant along with the application of EDTA significantly increased the phytoremediation efficiency.

Activated by Combined Magnrtic Field Gravitropic Reaction Reply on Nanodose of Biologicaly Active Compounds

NASA Astrophysics Data System (ADS)

Sheykina, Nadezhda; Bogatina, Nina

The new science direction nanotechnologies initiated a big jump in the pharmacology and medicine. This leads to the big development of homeopathy. The most interest appeared while investigating of the reaction of biological object on the nano dose of iologically substances. The changing of concentration (in nmol/l) of biologically active material is also possible during weak energy action. For instance, weak combined magnetic field may change a little the concentration of ions that are oriented parallel to the external magnetic field and, by the analogy with said above, lead to the similar effects. Simple estimations give the value for the threshold to the magnetic field by two orders smaller than the geomagnetic field. By this investigation we wanted to understand whether the analogy in the action of nano dose of biologically active substances and weak combined magnetic field presents and whether the action of one of these factors may be replaced by other one. The effect of one of biologically active substances NPA (Naphtyl-Phtalame Acid) solution with the concentration 0.01 mol/l on the gravitropic reaction of cress roots was investigated. It was shown that its effect was the inhibition of cress roots gravitropic reaction. The same inhibition was achieved by the combined magnetic field action on the cress roots, germinated in water. The alternative component of the combined magnetic field coincided formally with the cyclotron frequency of NPA ions. So the analogy in the action of nano dose of biologically active substances and weak combined magnetic field was shown. The combined magnetic field using allows to decrease sufficiently the dose of biologically active substances. This fact can be of great importance in pharmacy and medicine.

Life span and structure of ephemeral root modules of different functional groups from a desert system.

PubMed

Liu, Bo; He, Junxia; Zeng, Fanjiang; Lei, Jiaqiang; Arndt, Stefan K

2016-07-01

The terminal branch orders of plant root systems have been proposed as short-lived 'ephemeral' modules specialized for resource absorption. The occurrence of ephemeral root modules has so far only been reported for a temperate tree species and it is unclear if the concept also applies to other woody (shrub, tree) and herb species. Fine roots of 12 perennial dicotyledonous herb, shrub and tree species were monitored for two growing seasons using a branch-order classification, sequential sampling and rhizotrons in the Taklamakan desert. Two root modules existed in all three plant functional groups. Among the first five branch orders, the first two (perennial herbs, shrubs) or three (trees) root orders were ephemeral and had a primary anatomical structure, high nitrogen (N) concentrations, high respiration rates and very short life spans of 1-4 months, whereas the last two branch orders in all functional groups were perennial, with thicker diameters, no or collapsed cortex, distinct secondary growth, low N concentrations, low respiration rates, but much longer life spans. Ephemeral, short-lived root modules and long-lived, persistent root modules seem to be a general feature across many plant functional groups and could represent a basic root system design. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

The Ca2+ pump inhibitor, thapsigargin, inhibits root gravitropism in Arabidopsis thaliana.

PubMed

Urbina, Daniela C; Silva, Herman; Meisel, Lee A

2006-01-01

Thapsigargin, a specific inhibitor of most animal intracellular SERCA-type Ca2+ pumps present in the sarcoplasmic/endoplasmic reticulum, was originally isolated from the roots of the Mediterranean plant Thapsia gargancia L. Here, we demonstrate that this root-derived compound is capable of altering root gravitropism in Arabidopsis thaliana. Thapsigargin concentrations as low as 0.1 microM alter root gravitropism whereas under similar conditions cyclopiazonic acid does not. Furthermore, a fluorescently conjugated thapsigargin (BODIPY FL thapsigargin) suggests that target sites for thapsigargin are located in intracellular organelles in the root distal elongation zone and the root cap, regions known to regulate root gravitropism.

Effects of zinc toxicity on sugar beet (Beta vulgaris L.) plants grown in hydroponics.

PubMed

Sagardoy, R; Morales, F; López-Millán, A-F; Abadía, A; Abadía, J

2009-05-01

The effects of high Zn concentration were investigated in sugar beet (Beta vulgaris L.) plants grown in a controlled environment in hydroponics. High concentrations of Zn sulphate in the nutrient solution (50, 100 and 300 microm) decreased root and shoot fresh and dry mass, and increased root/shoot ratios, when compared to control conditions (1.2 microm Zn). Plants grown with excess Zn had inward-rolled leaf edges and a damaged and brownish root system, with short lateral roots. High Zn decreased N, Mg, K and Mn concentrations in all plant parts, whereas P and Ca concentrations increased, but only in shoots. Leaves of plants treated with 50 and 100 microm Zn developed symptoms of Fe deficiency, including decreases in Fe, chlorophyll and carotenoid concentrations, increases in carotenoid/chlorophyll and chlorophyll a/b ratios and de-epoxidation of violaxanthin cycle pigments. Plants grown with 300 microm Zn had decreased photosystem II efficiency and further growth decreases but did not have leaf Fe deficiency symptoms. Leaf Zn concentrations of plants grown with excess Zn were high but fairly constant (230-260 microg.g(-1) dry weight), whereas total Zn uptake per plant decreased markedly with high Zn supply. These data indicate that sugar beet could be a good model to investigate Zn homeostasis mechanisms in plants, but is not an efficient species for Zn phytoremediation.

The tropic response of plant roots to oxygen: oxytropism in Pisum sativum L

NASA Technical Reports Server (NTRS)

Porterfield, D. M.; Musgrave, M. E.

1998-01-01

Plant roots are known to orient growth through the soil by gravitropism, hydrotropism, and thigmotropism. Recent observations of plant roots that developed in a microgravity environment in space suggested that plant roots may also orient their growth toward oxygen (oxytropism). Using garden pea (Pisum sativum L. cv. Weibul's Apollo) and an agravitropic mutant (cv. Ageotropum), root oxytropism was studied in the controlled environment of a microrhizotron. A series of channels in the microrhizotron allowed establishment of an oxygen gradient of 0.8 mmol mol-1 mm-1. Curvature of seedling roots was determined prior to freezing the roots for subsequent spectrophotometric determinations of alcohol dehydrogenase activity. Oxytropic curvature was observed all along the gradient in both cultivars of pea. The normal gravitropic cultivar showed a maximal curvature of 45 degrees after 48 h, while the agravitropic mutant curved to 90 degrees. In each cultivar, the amount of curvature declined as the oxygen concentration decreased, and was linearly related to the root elongation rate. Since oxytropic curvature occurred in roots exposed to oxygen concentrations that were not low enough to induce the hypoxically responsive protein alcohol dehydrogenase, we suspect that the oxygen sensor associated with oxytropism does not control the induction of hypoxic metabolism. Our results indicate that oxygen can play a critical role in determining root orientation as well as impacting root metabolic status. Oxytropism allows roots to avoid oxygen-deprived soil strata and may also be the basis of an auto-avoidance mechanism, decreasing the competition between roots for water and nutrients as well as oxygen.

Phytoremediation of Heavy Metals in Contaminated Water and Soil Using Miscanthus sp. Goedae-Uksae 1.

PubMed

Bang, Jihye; Kamala-Kannan, Seralathan; Lee, Kui-Jae; Cho, Min; Kim, Chang-Hwan; Kim, Young-Jin; Bae, Jong-Hyang; Kim, Kyong-Ho; Myung, Hyun; Oh, Byung-Taek

2015-01-01

The aim of this study is to characterize the heavy metal phytoremediation potential of Miscanthus sp. Goedae-Uksae 1, a hybrid, perennial, bio-energy crop developed in South Korea. Six different metals (As, Cu, Pb, Ni, Cd, and Zn) were used for the study. The hybrid grass effectively absorbed all the metals from contaminated soil. The maximum removal was observed for As (97.7%), and minimum removal was observed for Zn (42.9%). Similarly, Goedae-Uksae 1 absorbed all the metals from contaminated water except As. Cd, Pb, and Zn were completely (100%) removed from contaminated water samples. Generally, the concentration of metals in roots was several folds higher than in shoots. Initial concentration of metals highly influenced the phytoremediation rate. The results of the bioconcentration factor, translocation factor, and enrichment coefficient tests indicate that Goedae-Uksae 1 could be used for phytoremediation in a marginally contaminated ecosystem.

Relationship between metal speciation in soil solution and metal adsorption at the root surface of ryegrass.

PubMed

Kalis, Erwin J J; Temminghoff, Erwin J M; Town, Raewyn M; Unsworth, Emily R; van Riemsdijk, Willem H

2008-01-01

The total metal content of the soil or total metal concentration in the soil solution is not always a good indicator for metal availability to plants. Therefore, several speciation techniques have been developed that measure a defined fraction of the total metal concentration in the soil solution. In this study the Donnan Membrane Technique (DMT) was used to measure free metal ion concentrations in CaCl(2) extractions (to mimic the soil solution, and to work under standardized conditions) of 10 different soils, whereas diffusive gradients in thin-films (DGT) and scanning chronopotentiometry (SCP) were used to measure the sum of free and labile metal concentrations in the CaCl(2) extracts. The DGT device was also exposed directly to the (wetted) soil (soil-DGT). The metal concentrations measured with the speciation techniques are related to the metal adsorption at the root surface of ryegrass (Lolium perenne L.), to be able to subsequently predict metal uptake. In most cases the metal adsorption related pH-dependently to the metal concentrations measured by DMT, SCP, and DGT in the CaCl(2) extract. However, the relationship between metal adsorption at the root surface and the metal concentrations measured by the soil-DGT was not-or only slightly-pH dependent. The correlations between metal adsorption at the root surface and metal speciation detected by different speciation techniques allow discussion about rate limiting steps in biouptake and the contribution of metal complexes to metal bioavailability.

Phytotoxicity of glyphosate in the germination of Pisum sativum and its effect on germinated seedlings

PubMed Central

2017-01-01

The present study evaluated the effects of glyphosate on Pisum sativum germination as well as its effect on the physiology and biochemistry of germinated seedlings. Different physico-chemical biomarkers, viz., chlorophyll, root and shoot length, total protein and soluble sugar, along with sodium and potassium concentration, were investigated in germinated seedlings at different glyphosate concentrations. This study reports the influence of different concentrations of glyphosate on pea seeds and seedlings. Physicochemical biomarkers were significantly changed by glyphosate exposure after 15 days. The germination of seedlings under control conditions (0 mg/L) was 100% after 3 days of treatment but at 3 and 4 mg/L glyphosate, germination was reduced to 55 and 40%, respectively. Physiological parameters like root and shoot length decreased monotonically with increasing glyphosate concentration, at 14 days of observation. Average root and shoot length (n=30 in three replicates) were reduced to 14.7 and 17.6%, respectively, at 4 mg/L glyphosate. Leaf chlorophyll content also decreased, with a similar trend to root and shoot length, but the protein content initially decreased and then increased with an increase in glyphosate concentration to 3 mg/L. The study suggests that glyphosate reduces the soluble sugar content significantly, by 21.6% (v/v). But internal sodium and potassium tissue concentrations were significantly altered by glyphosate exposure with increasing concentrations of glyphosate. Biochemical and physiological analysis also supports the inhibitory effect of glyphosate on seed germination and biochemical effects on seedlings. PMID:28728354

Comparative effects of simulated acid rain of different ratios of SO42- to NO3- on fine root in subtropical plantation of China.

PubMed

Liu, Xin; Zhao, Wenrui; Meng, Miaojing; Fu, Zhiyuan; Xu, Linhao; Zha, Yan; Yue, Jianmin; Zhang, Shuifeng; Zhang, Jinchi

2018-03-15

The influence of acid rain on forest trees includes direct effects on foliage as well as indirect soil-mediated effects that cause a reduction in fine-root growth. In addition, the concentration of NO 3 - in acid rain increases with the rapidly growing of nitrogen deposition. In this study, we investigated the impact of simulated acid rain with different SO 4 2- /NO 3 - (S/N) ratios, which were 5:1 (S), 1:1 (SN) and 1:5 (N), on fine-root growth from March 2015 to February 2016. Results showed that fine roots were more sensitive to the effects of acid rain than soils in the short-term. Both soil pH and fine root biomass (FRB) significantly decreased as acid rain pH decreased, and also decreased with the percentage of NO 3 - increased in acid rain. Acid rain pH significantly influenced soil total carbon and available potassium in summer. Higher acidity level (pH=2.5), especially of the N treatments, had the strongest inhibitory impact on soil microbial activity after summer. The structural equation modelling results showed that acid rain S/N ratio and pH had stronger direct effects on FRB than indirect effects via changed soil and fine root properties. Fine-root element contents and antioxidant enzymes activities were significantly affected by acid rain S/N ratio and pH during most seasons. Fine-root Al ion content, Ca/Al, Mg/Al ratios and catalase activity were used as better indicators than soil parameters for evaluating the effects of different acid rain S/N ratios and pH on forests. Our results suggest that the ratio of SO 4 2- to NO 3 - in acid rain is an important factor which could affect fine-root growth in subtropical forests of China. Copyright © 2017. Published by Elsevier B.V.

Arabidopsis thaliana RALF1 opposes brassinosteroid effects on root cell elongation and lateral root formation

PubMed Central

Moura, Daniel S.

2014-01-01

Rapid alkalinization factor (RALF) is a peptide signal that plays a basic role in cell biology and most likely regulates cell expansion. In this study, transgenic Arabidopsis thaliana lines with high and low levels of AtRALF1 transcripts were used to investigate this peptide’s mechanism of action. Overexpression of the root-specific isoform AtRALF1 resulted in reduced cell size. Conversely, AtRALF1 silencing increased root length by increasing the size of root cells. AtRALF1-silenced plants also showed an increase in the number of lateral roots, whereas AtRALF1 overexpression produced the opposite effect. In addition, four AtRALF1-inducible genes were identified: two genes encoding proline-rich proteins (AtPRP1 and AtPRP3), one encoding a hydroxyproline-rich glycoprotein (AtHRPG2), and one encoding a xyloglucan endotransglucosylase (TCH4). These genes were expressed in roots and involved in cell-wall rearrangement, and their induction was concentration dependent. Furthermore, AtRALF1-overexpressing plants were less sensitive to exogenous brassinolide (BL); upon BL treatment, the plants showed no increase in root length and a compromised increase in hypocotyl elongation. In addition, the treatment had no effect on the number of emerged lateral roots. AtRALF1 also induces two brassinosteroid (BR)-downregulated genes involved in the BR biosynthetic pathway: the cytochrome P450 monooxygenases CONSTITUTIVE PHOTOMORPHISM AND DWARFISM (CPD) and DWARF4 (DWF4). Simultaneous treatment with both AtRALF1 and BL caused a reduction in AtRALF1-inducible gene expression levels, suggesting that these signals may compete for components shared by both pathways. Taken together, these results indicate an opposing effect of AtRALF1 and BL, and suggest that RALF’s mechanism of action could be to interfere with the BR signalling pathway. PMID:24620000

Carboxylate metabolism in sugar beet plants grown with excess Zn.

PubMed

Sagardoy, R; Morales, F; Rellán-Álvarez, R; Abadía, A; Abadía, J; López-Millán, A F

2011-05-01

The effects of Zn excess on carboxylate metabolism were investigated in sugar beet (Beta vulgaris L.) plants grown hydroponically in a growth chamber. Root extracts of plants grown with 50 or 100μM Zn in the nutrient solution showed increases in several enzymatic activities related to organic acid metabolism, including citrate synthase and phosphoenolpyruvate carboxylase, when compared to activities in control root extracts. Root citric and malic acid concentrations increased in plants grown with 100μM Zn, but not in plants grown with 50μM Zn. In the xylem sap, plants grown with 50 and 100μM Zn showed increases in the concentrations of citrate and malate compared to the controls. Leaves of plants grown with 50 or 100μM Zn showed increases in the concentrations of citric and malic acid and in the activities of citrate synthase and fumarase. Leaf isocitrate dehydrogenase increased only in plants grown with 50μM Zn when compared to the controls. In plants grown with 300μM Zn, the only enzyme showing activity increases in root extracts was citrate synthase, whereas the activities of other enzymes decreased compared to the controls, and root citrate concentrations increased. In the 300μM Zn-grown plants, the xylem concentrations of citric and malic acids were higher than those of controls, whereas in leaf extracts the activity of fumarase increased markedly, and the leaf citric acid concentration was higher than in the controls. Based on our data, a metabolic model of the carboxylate metabolism in sugar beet plants grown under Zn excess is proposed. Copyright © 2010 Elsevier GmbH. All rights reserved.

Effects of landfill gas on subtropical woody plants

NASA Astrophysics Data System (ADS)

Chan, G. Y. S.; Wong, M. H.; Whitton, B. A.

1991-05-01

An account is given of the influence of landfill gas on tree growth in the field at Gin Drinkers' Bay (GDB) landfill, Hong Kong, and in the laboratory. Ten species ( Acacia confusa, Albizzia lebbek, Aporusa chinensis, Bombax malabaricum, Castanopsis fissa, Liquidambar formosana, Litsea glutinosa, Machilus breviflora, Pinus elliottii, and Tristania conferta), belonging to eight families, were transplanted to two sites, one with a high concentration of landfill gas in the cover soil (high-gas site, HGS) and the other with a relatively low concentration of gas (low-gas site, LGS). Apart from the gaseous composition, the general soil properties were similar. A strong negative correlation between tree growth and landfill gas concentration was observed. A laboratory study using the simulated landfill gas to fumigate seedlings of the above species showed that the adventitious root growth of Aporusa chinensis, Bombax malabaricum, Machilus breviflora, and Tristania confera was stimulated by the gas, with shallow root systems being induced. Acacia confusa, Albizzia lebbek, and Litsea glutinosa were gas-tolerant, while root growth of Castanopsis fissa, Liquidambar formosana, and Pinus elliottii was inhibited. In most cases, shoot growth was not affected, exceptions being Bombax malabaricum, Liquidambar formosana, and Tristania conferta, where stunted growth and/or reduced foliation was observed. A very high CO2 concentration in cover soil limits the depth of the root system. Trees with a shallow root system become very susceptible to water stress. The effects of low O2 concentration in soil are less important than the effects of high CO2 concentration. Acacia confusa, Albizzia lebbek, and Tristania conferta are suited for growth on subtropical completed landfills mainly due to their gas tolerance and/or drought tolerance.

Uptake of metals during chelant-assisted phytoextraction with EDDS related to the solubilized metal concentration.

PubMed

Tandy, Susan; Schulin, Rainer; Nowack, Bernd

2006-04-15

The use of chelants to enhance phytoextraction is one method being tested to make phytoextraction efficient enough to be used as a remediation technique for heavy metal pollution in the field. We performed pot experiments with sunflowers in order to investigate the use of the biodegradable chelating agent SS-EDDS for this purpose. We used singly and combined contaminated soils (Cu, Zn) and multimetal contaminated field soils (Cu, Zn, Cd, Pb). EDDS (10 mmol kg(-10 soil) increased soil solution metals greatly for Cu (factor 840-4260) and Pb (factor 100-315), and to a lesser extent for Zn (factor 23-50). It was found that Zn (when present as the sole metal), Cu, and Pb uptake by sunflowers was increased by EDDS, butin multimetal contaminated soil Zn and Cd were not. EDDS was observed in the sunflower roots and shoots at concentrations equal to metal uptake. The different metal uptake in the various soils can be related to a linear relationship between Cu and Zn in soil solution in the presence of EDDS and plant uptake, indicating the great importance of measuring and reporting soil solution metal concentrations in phytoextraction studies.

Heavy metal phytoextraction-natural and EDTA-assisted remediation of contaminated calcareous soils by sorghum and oat.

PubMed

Mahmood-Ul-Hassan, Muhammad; Suthar, Vishandas; Ahmad, Rizwan; Yousra, Munazza

2017-10-30

The abilities of sorghum (Sorghum bicolor L.) and oat (Avena sativa L.) to take up heavy metals from soils amended with ethylenediaminetetraacetic acid (EDTA) were assessed under greenhouse conditions. Both plants were grown in two soils contaminated with heavy metals (Gujranwala-silty loam and Pacca-clay loam). The soils were treated with 0, 0.625, 1.25, and 2.5 mM EDTA kg -1 soil applied at both 45 and 60 days after sowing (DAS); the experiment was terminated at 75 DAS. Addition of EDTA significantly increased concentrations of Cd, Cr, and Pb in roots and shoots, and bio-concentration factors and phytoextraction rates were also increased. Post-harvest soil analysis showed that soluble fractions of metals were also increased significantly. The increase in Cd was ≈ 3-fold and Pb was ≈ 15-fold at the highest addition of EDTA in Gujranwala soil; in the Pacca soil, the increase was less. Similarly, other phytoremediation factors, such as metal translocation, bio-concentration factor, and phytoextraction, efficiency were also maximum when soils were treated with 2.5 mM EDTA kg -1 soil. The study demonstrated that sorghum was better than oat for phytoremediation.

Vitality and chemistry of roots of red spruce in forest floors of stands with a gradient of soil Al/Ca ratios in the northeastern United States

Treesearch

Philip M. Wargo; Kristiina Vogt; Daniel Vogt; Quintaniay Holifield; Joel Tilley; Gregory Lawrence; Mark David

2003-01-01

Number of living root tips per branch, percent dead roots, percent mycorrhizae and mycorrhizal morphotype, response of woody roots to wounding and colonization by fungi, and concentrations of starch, soluble sugars, phenols, percent C and N and C/N ratio, and Al, Ca, Fe, K, Mg, Mn, and P were measured for 2 consecutive years in roots of red spruce (Picea...

Effect of Microbial inoculation in combating the aluminium toxicity effect on growth of Zea mays.

PubMed

Arora, P; Singh, G; Tiwari, A

2017-07-31

The present study is aimed at improving the aluminium tolerance in maize crop employing the potential of microbial inoculants in conferring resistance to these toxicities via production of certain chelating compounds like siderophores, exopolysachharides and organic acids. Acid soils have now-a-days become one of the key factors for limiting growth of many agriculturally important crops. Aluminium  is one of the major elements present in acid soils and is mainly responsible for toxicity in the soil. This aluminium is rapidly soluble in soil water and hence absorbed by plant roots under conditions where soil pH is below 5. This toxicity leads to severe root growth inhibition, thereby limiting the production of maize crops. It was observed that use of microbial inoculums can be helpful in elimination of these toxic compounds and prevent the inhibition of root growth . It was found that the soils contaminated with aluminium toxicity decreased the root length of maize plant significantly by 65% but Bacillus and Burkholderia inoculation increased this root length significantly by 1.4- folds and 2- folds respectively thereby combating the effect of aluminium toxicity. Aluminium concentration was found maximum in roots of plants which were grown under aluminium stress condition. But this aluminium accumulation decreased ̴ 2-folds when Burkholderia was used as seed inoculants under aluminium stress conditions. Also, at 60mM aluminium accumulation, phosphorus solubilisation in roots was found to be increased upto 30% on Burkholderia inoculation. However, Bacillus inoculation didn't show any significant difference in either of the case. Thus, the inoculation of seeds with Burkholderia isolates could prove to be a boon in sequestering aluminium toxicity in Zea mays.

Cadmium-Induced Changes in Antioxidative Systems, Hydrogen Peroxide Content, and Differentiation in Scots Pine Roots1

PubMed Central

Schützendübel, Andres; Schwanz, Peter; Teichmann, Thomas; Gross, Kristina; Langenfeld-Heyser, Rosemarie; Godbold, Douglas L.; Polle, Andrea

2001-01-01

To investigate whether Cd induces common plant defense pathways or unspecific necrosis, the temporal sequence of physiological reactions, including hydrogen peroxide (H2O2) production, changes in ascorbate-glutathione-related antioxidant systems, secondary metabolism (peroxidases, phenolics, and lignification), and developmental changes, was characterized in roots of hydroponically grown Scots pine (Pinus sylvestris) seedlings. Cd (50 μm, 6 h) initially increased superoxide dismutase, inhibited the systems involved in H2O2 removal (glutathione/glutathione reductase, catalase [CAT], and ascorbate peroxidase [APX]), and caused H2O2 accumulation. Elongation of the roots was completely inhibited within 12 h. After 24 h, glutathione reductase activities recovered to control levels; APX and CAT were stimulated by factors of 5.5 and 1.5. Cell death was increased. After 48 h, nonspecific peroxidases and lignification were increased, and APX and CAT activities were decreased. Histochemical analysis showed that soluble phenolics accumulated in the cytosol of Cd-treated roots but lignification was confined to newly formed protoxylem elements, which were found in the region of the root tip that normally constitutes the elongation zone. Roots exposed to 5 μm Cd showed less pronounced responses and only a small decrease in the elongation rate. These results suggest that in cells challenged by Cd at concentrations exceeding the detoxification capacity, H2O2 accumulated because of an imbalance of redox systems. This, in turn, may have triggered the developmental program leading to xylogenesis. In conclusion, Cd did not cause necrotic injury in root tips but appeared to expedite differentiation, thus leading to accelerated aging. PMID:11706171

Acclimation and soil moisture constrain sugar maple root respiration in experimentally warmed soil.

PubMed

Jarvi, Mickey P; Burton, Andrew J

2013-09-01

The response of root respiration to warmer soil can affect ecosystem carbon (C) allocation and the strength of positive feedbacks between climatic warming and soil CO2 efflux. This study sought to determine whether fine-root (<1 mm) respiration in a sugar maple (Acer saccharum Marsh.)-dominated northern hardwood forest would adjust to experimentally warmed soil, reducing C return to the atmosphere at the ecosystem scale to levels lower than that would be expected using an exponential temperature response function. Infrared heating lamps were used to warm the soil (+4 to +5 °C) in a mature sugar maple forest in a fully factorial design, including water additions used to offset the effects of warming-induced dry soil. Fine-root-specific respiration rates, root biomass, root nitrogen (N) concentration, soil temperature and soil moisture were measured from 2009 to 2011, with experimental treatments conducted from late 2010 to 2011. Partial acclimation of fine-root respiration to soil warming occurred, with soil moisture deficit further constraining specific respiration rates in heated plots. Fine-root biomass and N concentration remained unchanged. Over the 2011 growing season, ecosystem root respiration was not significantly greater in warmed soil. This result would not be predicted by models that allow respiration to increase exponentially with temperature and do not directly reduce root respiration in drier soil.

Vitality and chemistry of roots of red spruce in forest floors of stands with a gradient of soil Al/Ca ratios in the northeastern United States

USGS Publications Warehouse

Wargo, P.M.; Vogt, K.; Vogt, D.; Holifield, Q.; Tilley, J.; Lawrence, G.; David, M.

2003-01-01

Number of living root tips per branch, percent dead roots, percent mycorrhizae and mycorrhizal morphotype, response of woody roots to wounding and colonization by fungi, and concentrations of starch, soluble sugars, phenols, percent C and N and C/N ratio, and Al Ca, Fe, K, Mg, Mn, and P were measured for 2 consecutive years in roots of red spruce (Picea rubens Sarg.) in stands in the northeastern United States (nine in 1993 and two additional in 1994) dominated by red spruce and with a gradient of forest floor exchangeable Al/Ca ratios. Root vitality was measured for nonwoody and coarse woody roots; chemical variables were measured for nonwoody (<1 mm), fine woody (1 to <2 mm), and coarse woody (2 to <5 mm) roots. There were significant differences among sites for all variables, particularly in 1993, although few were related to the Al/Ca ratio gradient. Percent mycorrhizae decreased, while some morphotypes increased or decreased as the Al/Ca ratio increased. In nonwoody roots, N increased as the Al/Ca ratio increased. Most sampled trees appeared to be in good or fair health, suggesting that an adverse response of these root variables to high Al concentrations may be apparent only after a significant change in crown health.

Removing Arsenic and Antimony by Phragmites australis: Rhizofiltration Technology

NASA Astrophysics Data System (ADS)

Ghassemzadeh, F.; Yousefzadeh, H.; Arbab-Zavar, M. H.

Arsenic (As) and Antimony (Sb) are toxic heavy metals that often associated in contaminated environment. High As concentration is reported in Chelpo, Khorasan province, northeast Iran. This study examined the possibility of As and Sb in rhizofiltration by common reed, Phragmites australis. Plants collected from five sampling sites of Chelpo. As and Sb concentrations in roots and shoots were determined by Atomic absorption spectrometry. About 80% of total As accumulated in roots than shoot system. Maximum As and Sb accumulation in root and rhizomes were 84.5-16.20 and 73-10.20 ppb, respectively. As/Sb ratio of root and rhizome ranged from 35 to 194 and 10.42 to 99.9, respectively. Arsenic contents in roots of contaminated plants were significantly higher than antimony accumulation (p<0.01). There was antagonistic interaction between As, Sb with P contents in the roots of contaminated plants. Common reed establishment may be locally enhanced by significantly decreased phosphorous (1.79 and 1.18 times less than control plant root and rhizome), increased Iron (1.42 and 5.83 times more than control plant root and rhizome) Enzymatic antioxidants (Catalase, Ascorbate peroxidase and Guaicol peroxidase) increased significantly with increment of As uptake in root system. Root As and Sb accumulation with enhanced changes in metabolic changes indicates that P. australis could be used as As, Sb rhizofiltration agent in this region and similar contaminated area.

Alterations in cytosol free calcium in horseradish roots simultaneously exposed to lanthanum(III) and acid rain.

PubMed

Zhang, Xuanbo; Wang, Lihong; Zhou, Anhua; Zhou, Qing; Huang, Xiaohua

2016-04-01

The extensive use of rare earth elements (REEs) has increased their environmental levels. REE pollution concomitant with acid rain in many agricultural regions can affect crop growth. Cytosol free calcium ions (Ca(2+)) play an important role in almost all cellular activities. However, no data have been reported regarding the role of cytosol free Ca(2+) in plant roots simultaneously exposed to REE and acid rain. In this study, the effects of exposures to lanthanum(III) and acid rain, independently and in combination, on cytosol free Ca(2+) levels, root activity, metal contents, biomass, cytosol pH and La contents in horseradish roots were investigated. The simultaneous exposures to La(III) and acid rain increased or decreased the cytosol free Ca(2+) levels, depending on the concentration of La(III), and these effects were more evident than independent exposure to La(III) or acid rain. In combined exposures, cytosol free Ca(2+) played an important role in the regulation of root activity, metal contents and biomass. These roles were closely related to La(III) dose, acid rain strength and treatment mode (independent exposure or simultaneous exposure). A low concentration of La(III) (20 mg L(-1)) could alleviate the adverse effects on the roots caused by acid rain, and the combined exposures at higher concentrations of La(III) and acid rain had synergic effects on the roots. Copyright © 2015 Elsevier Inc. All rights reserved.

Synergistic interactions between leaf beetle herbivory and fire enhance tamarisk (Tamarix spp.) mortality

USGS Publications Warehouse

Drus, Gail M.; Dudley, Tom L.; Antonio, Carla M.; Even, Thomas J.; Brooks, Matt L.; Matchett, J.R.

2014-01-01

The combined effects of herbivory and fire on plant mortality were investigated using prescribed burns of tamarisk (Tamarix ramosissima Lebed) exposed to herbivory by the saltcedar leaf beetle (Chrysomelidae: Diorhabda carinulata Desbrocher). Tamarix stands in the Humboldt Sink (NV, USA) were divided into three treatments: summer burn (August 2006), fall burn (October 2006) and control (unburned), and litter depth was manipulated to vary fire intensity within burn seasons. A gradient of existing herbivory impact was described with three plant condition metrics prior to fire: reduced proportions of green canopy, percent root crown starch sampled at the height of the growing season (August 2006), and percent root crown starch measured during dormancy (December 2006). August root crown starch concentration and proportion green canopy were strongly correlated, although the proportion green canopy predicted mortality better than August root crown starch. December root crown starch concentration was more depleted in unburned trees and in trees burned during the summer than in fall burn trees. Mortality in summer burned trees was higher than fall burned trees due to higher fire intensity, but December root crown starch available for resprouting in the spring was also lower in summer burned trees. The greatest mortality was observed in trees with the lowest December root crown starch concentration which were exposed to high fire intensity. Disproportionate changes in the slope and curvature of prediction traces as fire intensity and December starch reach reciprocal maximum and minimum levels indicate that beetle herbivory and fire intensity are synergistic.

Acetylcholine causes rooting in leaf explants of in vitro raised tomato (Lycopersicon esculentum Miller) seedlings.

PubMed

Bamel, Kiran; Gupta, Shrish Chandra; Gupta, Rajendra

2007-05-30

The animal neurotransmitter acetylcholine (ACh) induces rooting and promotes secondary root formation in leaf explants of tomato (Lycopersicon esculentum Miller var. Pusa Ruby), cultured in vitro on Murashige and Skoog's medium. The roots originate from the midrib of leaf explants and resemble taproot. ACh at 10(-5) M was found to be the optimum over a wide range of effective concentrations between 10(-7) and 10(-3) M. The breakdown products, choline and acetate were ineffective even at 10(-3) M concentration. ACh appears to have a natural role in tomato rhizogenesis because exogenous application of neostigmine, an inhibitor of ACh hydrolysis, could mimic the effect of ACh. Neostigmine, if applied in combination with ACh, potentiated the ACh effect.

Effects of elevated root zone CO2 on xerophytic shrubs in re-vegetated sandy dunes at smaller spatial and temporal scales.

PubMed

Lei, Huang; Zhishan, Zhang

2015-01-01

The below-ground CO2 concentration in some crusted soils or flooded fields is usually ten or hundred times larger than the normal levels. Recently, a large number of studies have focused on elevated CO2 in the atmosphere; however, only few have examined the influence of elevated root zone CO2 on plant growth and vegetation succession. In the present study, a closed-air CO2 enrichment (CACE) system was designed to simulate elevated CO2 concentrations in the root zones. The physio-ecological characteristics of two typical xerophytic shrubs C. korshinskii and A. ordosica in re-vegetated desert areas were investigated at different soil CO2 concentrations from March 2011 to October 2013. Results showed that plant growth, phenophase, photosynthetic rate, stomatal conductance, transpiration rate, and water use efficiency for the two xerophytic shrubs were all increased at first and then decreased with increasing soil CO2 concentrations, and the optimal soil CO2 concentration thresholds for C. korshinskii and A. ordosica were 0.554 and 0.317%, respectively. And A. ordosica was more tolerate to root zone CO2 variation when compared with C. korshinskii, possible reasons and vegetation succession were also discussed.

Perturbation of auxin homeostasis by overexpression of wild-type IAA15 results in impaired stem cell differentiation and gravitropism in roots.

PubMed

Yan, Da-Wei; Wang, Jing; Yuan, Ting-Ting; Hong, Li-Wei; Gao, Xiang; Lu, Ying-Tang

2013-01-01

Aux/IAAs interact with auxin response factors (ARFs) to repress their transcriptional activity in the auxin signaling pathway. Previous studies have focused on gain-of-function mutations of domain II and little is known about whether the expression level of wild-type Aux/IAAs can modulate auxin homeostasis. Here we examined the perturbation of auxin homeostasis by ectopic expression of wild-type IAA15. Root gravitropism and stem cell differentiation were also analyzed. The transgenic lines were less sensitive to exogenous auxin and exhibited low-auxin phenotypes including failures in gravity response and defects in stem cell differentiation. Overexpression lines also showed an increase in auxin concentration and reduced polar auxin transport. These results demonstrate that an alteration in the expression of wild-type IAA15 can disrupt auxin homeostasis.

Copper uptake by Pteris melanocaulon Fée from a Copper-Gold mine in Surigao del Norte, Philippines.

PubMed

De la Torre, Joseph Benjamin B; Claveria, Rene Juna R; Perez, Rubee Ellaine C; Perez, Teresita R; Doronila, Augustine I

2016-01-01

The ability of some plants to take up metal contaminants in the soil has been of increasing interest as an environmental approach to pollution clean-up. This study aimed to assess the ability of Pteris melanocaulon for copper(Cu) uptake by determining the Cu levels in the fern vis-à-vis surrounding soil and the location of Cu accumulation within its biomass. It also aimed to add information to existing literature as P. melanocaulon are found to be less documented compared to other fern metal accumulators, such as P. vittata. The P. melanocaulon found in the Suyoc Pit of a Copper-Gold mine in Placer, Surigao del Norte, Philippines exhibited a high Bioaccumulation Factor(BF) of 4.04 and a low Translocation Factor(TF) of 0.01, suggesting more Cu accumulation in the roots (4590.22 ± 385.66 µg g(-1) Cu). Noteworthy was the Cu concentration in the rhizome which was also high (3539.44 ± 1696.35 µg g(-1) Cu). SEM/EDX analyses of the Cu content in the roots indicated high elemental %Cu in the xylem (6.95%) than in the cortex (2.68%). The high Cu content in the roots and rhizomes and the localization of Cu in the xylem manifested a potential utilization of the fern as a metallophyte for rhizofiltration and phytostabilization.

[Bidens maximowicziana's adsorption ability and remediation potential to lead in soils].

PubMed

Wang, Hong-qi; Li, Hua; Lu, Si-jin

2005-11-01

Bidens maximowicziana's adsorption ability and remediation potential to lead were studied. The results show: (1) The Bidens maximowicziana has a strong adsorption to lead, the concentration of lead in plants increased linearly with the increase of lead concentration in soil. Then maximum concentration was 1509.3 mg x kg(-1) in roots and 2164.7 mg x kg(-1) in shoots when lead concentration in soil was 2000 mg x L(-1); (2) The lead concentration distribution order in the Bidens maximorwicziana is: leaf>stem>root>seed, which indicate that Bidens maximowicziana has a strong ability to transfer lead; (3) Uptaking ability differes in different vegetal periods. Maximum lead uptaking rate occured in the period of blooming for 40-60 days, in which daily uptake capacity was 15.81 mg x (kg x d)(-1) in roots and 19.83 mg x (kg x d)(-1) in shoots respectively. It can be concluded that Bidens maximowicziana appeares to be a moderate Pb accumulator making it suitable for phytoremediation of Pb contaminated soil.

Impact of Variety and Agronomic Factors on Crude Protein and Total Lysine in Chicory; N(ε)-Carboxymethyl-lysine-Forming Potential during Drying and Roasting.

PubMed

Loaëc, Grégory; Niquet-Léridon, Céline; Henry, Nicolas; Jacolot, Philippe; Jouquand, Céline; Janssens, Myriam; Hance, Philippe; Cadalen, Thierry; Hilbert, Jean-Louis; Desprez, Bruno; Tessier, Frédéric J

2015-12-02

During the heat treatment of coffee and its substitutes some compounds potentially deleterious to health are synthesized by the Maillard reaction. Among these, N(ε)-carboxymethyl-lysine (CML) was detected at high levels in coffee substitutes. The objective of this study was to evaluate the impact of changes in agricultural practice on the lysine content present in chicory roots and try to limit CML formation during roasting. Of the 24 varieties analyzed, small variations in lysine content were observed, 213 ± 8 mg/100 g dry matter (DM). The formation of lysine tested in five commercial varieties was affected by the nitrogen treatment with mean levels of 176 ± 2 mg/100 g DM when no fertilizer was added and 217 ± 7 mg/100 g DM with a nitrogen supply of 120 kg/ha. The lysine content of fresh roots was significantly correlated to the concentration of CML formed in roasted roots (r = 0.51; p < 0.0001; n = 76).

Developmental and environmental effects on assimilate partitioning in Canada thistle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tworkoski, T.J.

1989-04-01

Canada thistle (Cirsium arvense) plants at three stages of development (rosette, bolt, and flower bud) were grown under spring-simulated or fall-simulated environments. Sucrose export from a single leaf exposed to {sup 14}CO{sub 2} was significantly greater in rosette-plants than bolt- or flower bud-plants during the first two hours after pulse. Twenty-four hours after pulse, total {sup 14}C translocation (dpm) was the same in both environments but the {sup 14}C concentration (dpm/gm) was greater in roots of fall-grown plants. Shoot meristem respiration of fall-grown plants was approximately 50% less than spring-grown plants and was a factor responsible for this trend. Concentrationsmore » of inulin and water-insoluble starch were greater in roots of fall-grown than spring-grown plants and pulsed {sup 14}C accumulated in these fractions. The results suggest that a shift in respiration and metabolism of fall-grown rosette- and bolt-plants leads to increased assimilate movement to the root which may have practical implications for control of this weed.« less

SOIL RESPIRED D13C SIGNATURES REFLECT ROOT EXUDATE OR ROOT TURNOVER SIGNATURES IN AN ELEVATED CO2 AND OZONE MESOCOSM EXPERIMENT

EPA Science Inventory

Bulk tissue and root and soil respired d13C signatures were measured throughout the soil profile in a Ponderosa Pine mesocosm experiment exposed to ambient and elevated CO2 concentrations. For the ambient treatment, root (0-1mm, 1-2mm, and >2mm) and soil d13C signatures were ?24...

Assessment of Cracks in Stress Concentration Regions with Localized Plastic Zones

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedman, E.

1998-11-25

Marty brittle fracture evaluation procedures include plasticity corrections to elastically computed stress intensity factors. These corrections, which are based on the existence of a plastic zone in the vicinity of the crack tip, can overestimate the plasticity effect for a crack embedded in a stress concentration region in which the elastically computed stress exceeds the yield strength of the material in a localized zone. The interactions between the crack, which acts to relieve the high stresses driving the crack, plasticity effects in the stress concentration region, and the nature and source of the loading are examined by formulating explicit flawmore » finite element models for a crack emanating from the root of a notch located in a panel subject to an applied tensile stress. The results of these calculations provide conditions under which a crack-tip plasticity correction based on the Irwin plastic zone size overestimates the plasticity effect. A failure assessment diagram (FAD) curve is used to characterize the effect of plasticity on the crack driving force and to define a less restrictive plasticity correction for cracks at notch roots when load-controlled boundary conditions are imposed. The explicit flaw finite element results also demonstrate that stress intensity factors associated with load-controlled boundary conditions, such as those inherent in the ASME Boiler and Pressure Vessel Code as well as in most handbooks of stress intensity factors, can be much higher than those associated with displacement-controlled conditions, such as those that produce residual or thermal stresses. Under certain conditions, the inclusion of plasticity effects for cracks loaded by displacement-controlled boundary conditions reduces the crack driving force thus justifying the elimination of a plasticity correction for such loadings. The results of this study form the basis for removing unnecessary conservatism from flaw evaluation procedures that utilize plasticity corrections.« less

Uptake of Plutonium-238 into Solanum tuberosum L. (potato plants) in presence of complexing agent EDTA.

PubMed

Tawussi, Frank; Gupta, Dharmendra K; Mühr-Ebert, Elena L; Schneider, Stephanie; Bister, Stefan; Walther, Clemens

2017-11-01

Bioavailability and plant uptake of radionuclides depend on various factors. Transfer into different plant parts depends on chemical and physical processes, which need to be known for realistic ingestion dose modelling when these plants are used for food. Within the scope of the present work, the plutonium uptake by potato plants (Solanum tuberosum L.) was investigated in hydroponic solution of low concentration [Pu] = 10 -9  mol L -1 . Particular attention was paid to the speciation of radionuclides in the solution which was modelled by the speciation code PHREEQC. The speciation, the solubility and therefore the plant availability of radionuclides mainly depend on the pH value and the redox potential of the solution. During the contamination period, the redox potential did not change significantly. In contrast, the pH value showed characteristic changes depending on exudates excreted by the plants. Plant roots took up high amounts of plutonium (37%-50% of the added total amount). In addition to the uptake into the roots, the radionuclides can also adsorb to the exterior root surface. The solution-to-plant transfer factor showed values between 0.03 and 0.80 (Bq kg -1 / Bq L -1 ) for the potato tubers. By addition of the complexing agent EDTA (10 -4  mol L-1), the plutonium uptake from solution increased by 58% in tubers and by 155% in shoots/leaves. The results showed that excreted substances by plants affect bioavailability of radionuclides at low concentration, on the one hand. On the other hand, the uptake of plutonium by roots and the accumulation in different plant parts can lead to non-negligible ingestion doses, even at low concentration. We are aware of the limited transferability of data obtained in hydroponic solutions to plants growing in soil. However, the aim of this study is twofold: First we want to investigate the influence of Pu speciation on plant uptake in a rather well defined system which can be modelled using available thermodynamic data. Second, techniques developed here shall be applied to the investigation of plants growing in soil in the future. The present work contributes to the basic understanding how plant induced effects on nutrient solution influence bioavailability of radionuclides and fosters the need for more detailed investigations of the complex uptake and accumulation processes of radionuclides into plants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Interactive effects of soil acidity and fluoride on soil solution aluminium chemistry and barley (Hordeum vulgare L.) root growth.

PubMed

Manoharan, V; Loganathan, P; Tillman, R W; Parfitt, R L

2007-02-01

A greenhouse study was conducted to determine if concentrations of fluoride (F), which would be added to acid soils via P fertilisers, were detrimental to barley root growth. Increasing rates of F additions to soil significantly increased the soil solution concentrations of aluminium (Al) and F irrespective of the initial adjusted soil pH, which ranged from 4.25 to 5.48. High rates of F addition severely restricted root growth; the effect was more pronounced in the strongly acidic soil. Speciation calculations demonstrated that increasing rates of F additions substantially increased the concentrations of Al-F complexes in the soil. Stepwise regression analysis showed that it was the combination of the activities of AlF2(1+) and AlF(2+) complexes that primarily controlled barley root growth. The results suggested that continuous input of F to soils, and increased soil acidification, may become an F risk issue in the future.

Transcription Factor-Mediated Control of Anthocyanin Biosynthesis in Vegetative Tissues1[OPEN

PubMed Central

Outchkourov, Nikolay S.; Schrama, Xandra; Blilou, Ikram; Jongedijk, Esmer; Simon, Carmen Diez; Bosch, Dirk; Hall, Robert D.

2018-01-01

Plants accumulate secondary metabolites to adapt to environmental conditions. These compounds, here exemplified by the purple-colored anthocyanins, are accumulated upon high temperatures, UV-light, drought, and nutrient deficiencies, and may contribute to tolerance to these stresses. Producing compounds is often part of a more broad response of the plant to changes in the environment. Here we investigate how a transcription-factor-mediated program for controlling anthocyanin biosynthesis also has effects on formation of specialized cell structures and changes in the plant root architecture. A systems biology approach was developed in tomato (Solanum lycopersicum) for coordinated induction of biosynthesis of anthocyanins, in a tissue- and development-independent manner. A transcription factor couple from Antirrhinum that is known to control anthocyanin biosynthesis was introduced in tomato under control of a dexamethasone-inducible promoter. By application of dexamethasone, anthocyanin formation was induced within 24 h in vegetative tissues and in undifferentiated cells. Profiles of metabolites and gene expression were analyzed in several tomato tissues. Changes in concentration of anthocyanins and other phenolic compounds were observed in all tested tissues, accompanied by induction of the biosynthetic pathways leading from Glc to anthocyanins. A number of pathways that are not known to be involved in anthocyanin biosynthesis were observed to be regulated. Anthocyanin-producing plants displayed profound physiological and architectural changes, depending on the tissue, including root branching, root epithelial cell morphology, seed germination, and leaf conductance. The inducible anthocyanin-production system reveals a range of phenomena that accompanies anthocyanin biosynthesis in tomato, including adaptions of the plants architecture and physiology. PMID:29192027

Silicon Decreases Dimethylarsinic Acid Concentration in Rice Grain and Mitigates Straighthead Disorder.

PubMed

Limmer, Matthew Alan; Wise, Patrick; Dykes, Gretchen E; Seyfferth, Angelia L

2018-04-17

While root Si transporters play a role in the uptake of arsenite and organic As species dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) in rice ( Oryza sativa L.), the impact of Si addition on the accumulation of DMA and MMA in reproductive tissues has not been directly evaluated, particularly in isolation from inorganic As species. Furthermore, DMA and MMA are suspected causal agents of straighthead disorder. We performed a hydroponic study to disentangle the impact of Si on accumulation of DMA and MMA in rice grain. At 5 μM, MMA was toxic to rice, regardless of Si addition, although Si significantly decreased root MMA concentrations. Plants dosed with 5 μM DMA grew well vegetatively but exhibited straighthead disorder at the lowest Si dose, and this DMA-induced yield loss reversed with increasing solution Si. Increasing Si also significantly decreased DMA concentrations in roots, straw, husk, and grain, particularly in mature plants. Si restricted grain DMA through competition for root uptake and downregulation of root Si transporters particularly at later stages of growth when Si uptake was greatest. Our finding that DMA causes straighthead disorder under low Si availability but not under high Si availability suggests Si as a straighthead management strategy.

Sublethal concentrations of salicylic acid decrease the formation of reactive oxygen species but maintain an increased nitric oxide production in the root apex of the ethylene-insensitive Never ripe tomato mutants

PubMed Central

Poór, Péter; Gémes, Katalin

2011-01-01

The pattern of salicylic acid (SA)-induced production of reactive oxygen species (ROS) and nitric oxide (NO) were different in the apex of adventitious roots in wild-type and in the ethylene-insensitive Never ripe (Nr) mutants of tomato (Solanum lycopersicum L. cv Ailsa Craig). ROS were upregulated, while NO remained at the control level in apical root tissues of wildtype plants exposed to sublethal concentrations of SA. In contrast, Nr plants expressing a defective ethylene receptor displayed a reduced level of ROS and a higher NO content in the apical root cells. In wild-type plants NO production seems to be ROS(H2O2)-dependent at cell death-inducing concentrations of SA, indicating that ROS and NO may interact to trigger oxidative cell death. In the absence of significant ROS accumulation, the increased NO production caused moderate reduction in cell viability in root apex of Nr plants exposed to 10−3 M SA. This suggests that a functional ethylene signaling pathway is necessary for the control of ROS and NO production induced by SA. PMID:21847015

Iron deficiency affects nitrogen metabolism in cucumber (Cucumis sativus L.) plants

PubMed Central

2012-01-01

Background Nitrogen is a principal limiting nutrient in plant growth and development. Among factors that may limit NO3- assimilation, Fe potentially plays a crucial role being a metal cofactor of enzymes of the reductive assimilatory pathway. Very few information is available about the changes of nitrogen metabolism occurring under Fe deficiency in Strategy I plants. The aim of this work was to study how cucumber (Cucumis sativus L.) plants modify their nitrogen metabolism when grown under iron deficiency. Results The activity of enzymes involved in the reductive assimilation of nitrate and the reactions that produce the substrates for the ammonium assimilation both at root and at leaf levels in Fe-deficient cucumber plants were investigated. Under Fe deficiency, only nitrate reductase (EC 1.7.1.1) activity decreased both at the root and leaf level, whilst for glutamine synthetase (EC 6.3.1.2) and glutamate synthase (EC 1.4.1.14) an increase was found. Accordingly, the transcript analysis for these enzymes showed the same behaviour except for root nitrate reductase which increased. Furthermore, it was found that amino acid concentration greatly decreased in Fe-deficient roots, whilst it increased in the corresponding leaves. Moreover, amino acids increased in the xylem sap of Fe-deficient plants. Conclusions The data obtained in this work provided new insights on the responses of plants to Fe deficiency, suggesting that this nutritional disorder differentially affected N metabolism in root and in leaf. Indeed under Fe deficiency, roots respond more efficiently, sustaining the whole plant by furnishing metabolites (i.e. aa, organic acids) to the leaves. PMID:23057967

Soil decontamination of 2,4,6- trinitrotoluene by alfalfa (Medicago sativa).

PubMed

Fallahi, S; Habibi-Rezaei, M; Khayami, M; Heydari, R

2007-12-15

Present study investigate the toxicity effect of 2,4,6-trinitrotoluene (TNT) on a terrestrial plant, alfalfa (Medicago sativa) in artificial soils. In this study, TNT toxicity assessment was performed on spiked silica with this nitroaromatic compound by determination of the percent of emergence and shoots and roots biomasses at the concentration range of 3.2-10000 mg kg(-1) Dry Weight (DW). The emergence was reduced by 22-32% after 5 days of exposure at TNT concentrations up to 100 mg kg(-1) DW; shoot and root biomasses were reduced by 48-50 and 63-74%, respectively after 30 days exposure at TNT concentrations < or = 32 mg kg(-1) DW. Concentrations higher than 100 mg kg(-1) DW can not be tolerated at all. Concentrations of TNT and its metabolites in silica, root and shoot were measured by High-Performance Liquid Chromatography (HPLC). Analyses of TNT spiked soil extracts reveal hat during alfalfa cultivation for 30 days, TNT was partially transformed at the extent of 15-27%. This transformation decreased at higher TNT soil concentrations. TNT is taken up and metabolized by plants to its downstream derivatives.

GTL1 and DF1 regulate root hair growth through transcriptional repression of ROOT HAIR DEFECTIVE 6-LIKE 4 in Arabidopsis

PubMed Central

Breuer, Christian; Kawamura, Ayako; Clark, Natalie M.; Morohashi, Kengo; Busch, Wolfgang; Benfey, Philip N.; Sozzani, Rosangela

2018-01-01

ABSTRACT How plants determine the final size of growing cells is an important, yet unresolved, issue. Root hairs provide an excellent model system with which to study this as their final cell size is remarkably constant under constant environmental conditions. Previous studies have demonstrated that a basic helix-loop helix transcription factor ROOT HAIR DEFECTIVE 6-LIKE 4 (RSL4) promotes root hair growth, but how hair growth is terminated is not known. In this study, we demonstrate that a trihelix transcription factor GT-2-LIKE1 (GTL1) and its homolog DF1 repress root hair growth in Arabidopsis. Our transcriptional data, combined with genome-wide chromatin-binding data, show that GTL1 and DF1 directly bind the RSL4 promoter and regulate its expression to repress root hair growth. Our data further show that GTL1 and RSL4 regulate each other, as well as a set of common downstream genes, many of which have previously been implicated in root hair growth. This study therefore uncovers a core regulatory module that fine-tunes the extent of root hair growth by the orchestrated actions of opposing transcription factors. PMID:29439132

Comparative Analysis of Crack Propagation in Roots with Hand and Rotary Instrumentation of the Root Canal -An Ex-vivo Study.

PubMed

Kumari, Manju Raj; Krishnaswamy, Manjunath Mysore

2016-07-01

Success of any endodontic treatment depends on strict adherence to 'endodontic triad'. Preparation of root canal system is recognized as being one of the most important stages in root canal treatment. At times, we inevitably end up damaging root dentin which becomes a Gateway for infections like perforation, zipping, dentinal cracks and minute intricate fractures or even vertical root fractures, thereby resulting in failure of treatment. Several factors may be responsible for the formation of dentinal cracks like high concentration of sodium hypochlorite, compaction methods and various canal shaping methods. To compare and evaluate the effects of root canal preparation techniques and instrumentation length on the development of apical root cracks. Seventy extracted premolars with straight roots were mounted on resin blocks with simulated periodontal ligaments, exposing 1-2 mm of the apex followed by sectioning of 1mm of root tip for better visualization under stereomicroscope. The teeth were divided into seven groups of 10 teeth each - a control group and six experimental groups. Subgroup A & B were instrumented with: Stainless Steel hand files (SS) up to Root Canal Length (RCL) & (RCL -1 mm) respectively; sub group C & D were instrumented using ProTaper Universal (PTU) up to RCL and (RCL -1mm) respectively; subgroup E & F were instrumented using ProTaper Next (PTN) up to RCL & (RCL -1 mm) respectively. Stereomicroscopic images of the instrumentation sequence were compared for each tooth. The data was analyzed statistically using descriptive analysis by 'Phi' and 'Cramers' test to find out statistical significance between the groups. The level of significance was set at p< 0.05 using SPSS software. Stainless steel hand file group showed most cracks followed by ProTaper Universal & ProTaper Next though statistically not significant. Samples instrumented up to 1mm short of working length (RCL-1mm) showed lesser number of cracks. All groups showed cracks formation, the stainless steel group being the highest. Working 1mm short of apex reduces the incidence of crack formation.

Effects of Crown Scorch on Longleaf Pine Fine Roots

Treesearch

Mary Anne Sword; James D. Haywood

1999-01-01

Photosynthate production is reduced by foliage loss. Thus, scorch-induced decreases in the leaf area of longleaf pine (Pinus palustris Mill.) may reduce photosynthate allocation to roots. In this investigation the root carbohydrate concentrations and dynamics of longleaf pine after two intensities of prescribed burning were monitored. In...

Seasonal changes in carbohydrate levels in roots of sugar maple

Treesearch

Philip M. Wargo; Philip M. Wargo

1971-01-01

This study was done to determine the normal complement of individual carbohydrates present in roots of sugar maples duringthe year and to obtain, as a basis for future comparison, an estimate of the normal variation and range of concentrations of individual carbohydrates in the roots during the year.

Nodule activity and allocation of photosynthate of soybean during recovery from water stress

NASA Technical Reports Server (NTRS)

Fellows, R. J.; Patterson, R. P.; Raper, C. D. Jr; Harris, D.; Raper CD, J. r. (Principal Investigator)

1987-01-01

Nodulated soybean plants (Glycine max [L.] Merr. cv Ransom) in a growth-chamber study were subjected to a leaf water potential (psi w) of -2.0 megapascal during vegetative growth. Changes in nonstructural carbohydrate contents of leaves, stems, roots, and nodules, allocation of dry matter among plant parts, in situ specific nodule activity, and in situ canopy apparent photosynthetic rate were measured in stressed and nonstressed plants during a 7-day period following rewatering. Leaf and nodule psi w also were determined. At the time of maximum stress, concentration of nonstructural carbohydrates had declined in leaves of stressed, relative to nonstressed, plants, and the concentration of nonstructural carbohydrates had increased in stems, roots, and nodules. Sucrose concentrations in roots and nodules of stressed plants were 1.5 and 3 times greater, respectively, than those of nonstressed plants. Within 12 hours after rewatering, leaf and nodule psi w of stressed plants had returned to values of nonstressed plants. Canopy apparent photosynthesis and specific nodule activity of stressed plants recovered to levels for nonstressed plants within 2 days after rewatering. The elevated sucrose concentrations in roots and nodules of stressed plants also declined rapidly upon rehydration. The increase in sucrose concentration in nodules, as well as the increase of carbohydrates in roots and stems, during water stress and the rapid disappearance upon rewatering indicates that inhibition of carbohydrate utilization within the nodule may be associated with loss of nodule activity. Availability of carbohydrates within the nodules and from photosynthetic activity following rehydration of nodules may mediate the rate of recovery of N2-fixation activity.

The Rice E3-Ubiquitin Ligase HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENE1 Modulates the Expression of ROOT MEANDER CURLING, a Gene Involved in Root Mechanosensing, through the Interaction with Two ETHYLENE-RESPONSE FACTOR Transcription Factors1

PubMed Central

Lourenço, Tiago F.; Serra, Tânia S.; Cordeiro, André M.; Swanson, Sarah J.; Gilroy, Simon; Saibo, Nelson J.M.; Oliveira, M. Margarida

2015-01-01

Plant roots can sense and respond to a wide diversity of mechanical stimuli, including touch and gravity. However, little is known about the signal transduction pathways involved in mechanical stimuli responses in rice (Oryza sativa). This work shows that rice root responses to mechanical stimuli involve the E3-ubiquitin ligase rice HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENE1 (OsHOS1), which mediates protein degradation through the proteasome complex. The morphological analysis of the roots in transgenic RNA interference::OsHOS1 and wild-type plants, exposed to a mechanical barrier, revealed that the OsHOS1 silencing plants keep a straight root in contrast to wild-type plants that exhibit root curling. Moreover, it was observed that the absence of root curling in response to touch can be reverted by jasmonic acid. The straight root phenotype of the RNA interference::OsHOS1 plants was correlated with a higher expression rice ROOT MEANDER CURLING (OsRMC), which encodes a receptor-like kinase characterized as a negative regulator of rice root curling mediated by jasmonic acid. Using the yeast two-hybrid system and bimolecular fluorescence complementation assays, we showed that OsHOS1 interacts with two ETHYLENE-RESPONSE FACTOR transcription factors, rice ETHYLENE-RESPONSIVE ELEMENT BINDING PROTEIN1 (OsEREBP1) and rice OsEREBP2, known to regulate OsRMC gene expression. In addition, we showed that OsHOS1 affects the stability of both transcription factors in a proteasome-dependent way, suggesting that this E3-ubiquitin ligase targets OsEREBP1 and OsEREBP2 for degradation. Our results highlight the function of the proteasome in rice response to mechanical stimuli and in the integration of these signals, through hormonal regulation, into plant growth and developmental programs. PMID:26381316

New biomimetic approach to determine the bioavailability of triclosan in soils and its validation with the wheat plant uptake bioassay.

PubMed

Jachero, Lourdes; Ahumada, Inés; Fuentes, Edwar; Richter, Pablo

2015-01-01

A new biomimetic approach for triclosan (TCS) was developed based on the leaching of the analyte from different biosolid-amended agricultural soils and the subsequent extraction of the leachates, using a rotating disk sorptive extraction (RDSE) procedure. The leaching equilibrium for TCS was reached at 3h when the ISO method (ISO/TS 21268-1:2007) was followed. The concentrations determined by this biomimetic method were compared with the bioavailability of TCS, determined by its accumulation in the roots of wheat plants grown in the same soil-biosolid systems. It was observed that the amount of organic matter in the soil matrix was a determining factor for mobilization of TCS. An increasing biosolid rate applied to soils resulted in a reduced mobility of TCS because the high amount of organic matter provided by the biosolid increased the hydrophobic interaction between TCS and the matrix. Similarly, increasing biosolid concentrations in the soil significantly decreased the bioavailability of TCS to the wheat plant. Thus, the bioavailability factor in wheat roots decreased from 0.22 to 0.08 for a soil having a pH of 8.2, when the biosolid rate was increased from 30 to 200 Mg ha(-1), respectively. A significant correlation (R=0.98) was obtained between TCS concentration in wheat plants and the proposed biomimetic methodology, indicating that the latter can predict the bioavailability in a time period as short as 180 min. The results of this study confirm our previous findings that amending soils with biosolids is beneficial for immobilizing low polarity contaminants and helps prevent their percolation through the soil profile and into groundwater. Copyright © 2014 Elsevier Ltd. All rights reserved.

In vitro evaluation of free radical scavenging activity of Codariocalyx motorius root extract.

PubMed

Chidambaram, Uma; Pachamuthu, Vanitha; Natarajan, Suganya; Elango, Bhakkiyalakshmi; Suriyanarayanan; Ramkumar, Kunga Mohan

2013-03-01

To determine the phenolic content in Codariocalyx motorius root extract and to evaluate its antioxidant properties using various in vitro assay systems. The antioxidant activity was evaluated based on scavenging of 1,1-diphenyl-2-picrylhydrazyl, hydroxyl radicals, superoxide anions, nitric oxide, hydrogen peroxide, peroxynitrite, reducing power and by inhibition of lipid peroxidation which was estimated in terms of thiobarbituric acid reactive substances. The root extract of the Codariocalyx motorius (C. motorius) exhibited potent total antioxidant activity that increased with increasing amount of extract concentration, which was compared with standard drug such as quercetin, butylated hydroxytoluene, tocopherol at different concentrations. The different concentrations of the extracts showed inhibition on lipid peroxidation. In addition, the extracts had effective reducing power, free radical scavenging, super oxide anion scavenging, nitric oxide scavenging, lipid peroxidation, and total phenolic content depending on concentration. High correlation between total phenolic contents and scavenging potential of different reactive oxygen species (r(2)=0.831-0.978) indicated the polyphenols as the main antioxidants. Codariocalyx motorius (C. motorius) root possess the highly active antioxidant substance which can be used for the treatment of oxidative stress-related diseases. Copyright © 2013 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

Drought tolerance, xylem sap abscisic acid and stomatal conductance during soil drying: a comparison of canopy trees of three temperate deciduous angiosperms.

PubMed

Loewenstein, Nancy J.; Pallardy, Stephen G.

1998-07-01

Patterns of water relations, xylem sap abscisic acid concentration ([ABA]) and stomatal aperture were characterized and compared in drought-sensitive black walnut (Juglans nigra L.), less drought-sensitive sugar maple (Acer saccharum Marsh.) and drought-tolerant white oak (Quercus alba L.) trees co-occurring in a second-growth forest in Missouri, USA. There were strong correlations among reduction in predawn leaf water potential, increased xylem sap [ABA] and stomatal closure in all species. Stomatal conductance was more closely correlated with xylem sap ABA concentration than with ABA flux or xylem sap pH and cation concentrations. In isohydric black walnut, increased concentrations of ABA in the xylem sap appeared to be primarily of root origin, causing stomatal closure in response to soil drying. In anisohydric sugar maple and white oak, however, there were reductions in midday leaf water potential associated with stomatal closure, making it uncertain whether drought-induced xylem sap ABA was of leaf or root origin. The role of root-originated xylem sap ABA in these species as a signal to the shoot of the water status of the roots is, therefore, less certain.

Bark analysis as a guide to cassava nutrition in Sierra Leone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Godfrey-Sam-Aggrey, W.; Garber, M.J.

1979-01-01

Cassava main stem barks from two experiments in which similar fertilizers were applied directly in a 2/sup 5/ confounded factorial design were analyzed and the bark nutrients used as a guide to cassava nutrition. The application of multiple regression analysis to the respective root yields and bark nutrient concentrations enable nutrient levels and optimum adjusted root yields to be derived. Differences in bark nutrient concentrations reflected soil fertility levels. Bark analysis and the application of multiple regression analysis to root yields and bark nutrients appear to be useful tools for predicting fertilizer recommendations for cassava production.

Study of oxidative stress related responses induced in Arabidopsis thaliana following mixed exposure to uranium and cadmium.

PubMed

Vanhoudt, Nathalie; Vandenhove, Hildegarde; Horemans, Nele; Wannijn, Jean; Bujanic, Andelko; Vangronsveld, Jaco; Cuypers, Ann

2010-01-01

In this study, toxicity effects in plants of uranium in a binary pollution condition were investigated by studying biological responses and unraveling oxidative stress related mechanisms in Arabidopsis thaliana seedlings, grown on hydroponics and exposed for 3 days to 10 μM uranium in combination with 5 μM cadmium. While uranium mostly accumulated in the roots with very low root-to-shoot transport, cadmium was taken up less by the roots but showed higher translocation to the shoots. Under mixed exposure, cadmium influenced uranium uptake highly but not the other way round resulting in a doubled uranium concentration in the roots. Under our mixed exposure conditions, it is clear that micronutrient concentrations in the roots are strongly influenced by addition of cadmium as a second stressor, while leaf macronutrient concentrations are mostly influenced by uranium. Oxidative stress related responses are highly affected by cadmium while uranium influence is more limited. Hereby, an important role was attributed to the ascorbate redox balance together with glutathione as both metabolites, but more explicitly for ascorbate, increased their reduced form, indicating an important defense and regulatory function. While for roots, based on an increase in FSD1 gene expression, oxidative stress was suggested to be superoxide induced, in leaves on the other hand, hydrogen peroxide related genes were mostly altered. Copyright © 2010 Elsevier Masson SAS. All rights reserved.