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Sample records for arabidopsis thaliana leaf

  1. A mutational analysis of leaf morphogenesis in Arabidopsis thaliana.

    PubMed Central

    Berná, G; Robles, P; Micol, J L

    1999-01-01

    As a contribution to a better understanding of the developmental processes that are specific to plants, we have begun a genetic analysis of leaf ontogeny in the model system Arabidopsis thaliana by performing a large-scale screening for mutants with abnormal leaves. After screening 46,159 M2 individuals, arising from 5770 M1 parental seeds exposed to EMS, we isolated 1926 M2 putative leaf mutants, 853 of which yielded viable M3 inbred progeny. Mutant phenotypes were transmitted with complete penetrance and small variations in expressivity in 255 lines. Most of them were inherited as recessive monogenic traits, belonging to 94 complementation groups, which suggests that we did not reach saturation of the genome. We discuss the nature of the processes presumably perturbed in the phenotypic classes defined among our mutants. PMID:10353913

  2. Use of a SPAD-502 meter to measure leaf chlorophyll concentration in Arabidopsis thaliana.

    PubMed

    Ling, Qihua; Huang, Weihua; Jarvis, Paul

    2011-02-01

    The SPAD-502 meter is a hand-held device that is widely used for the rapid, accurate and non-destructive measurement of leaf chlorophyll concentrations. It has been employed extensively in both research and agricultural applications, with a range of different plant species. However, its utility has not been fully exploited in relation to the most intensively studied model organism for plant science research, Arabidopsis thaliana. Measurements with the SPAD-502 meter produce relative SPAD meter values that are proportional to the amount of chlorophyll present in the leaf. In order to convert these values into absolute units of chlorophyll concentration, calibration curves must be derived and utilized. Here, we present calibration equations for Arabidopsis that can be used to convert SPAD values into total chlorophyll per unit leaf area (nmol/cm(2); R(2) = 0.9960) or per unit fresh weight of leaf tissue (nmol/mg; R(2) = 0.9809). These relationships were derived using a series of Arabidopsis chloroplast biogenesis mutants that exhibit chlorophyll deficiencies of varying severity, and were verified by the subsequent analysis of senescent or light-stressed leaves. Our results revealed that the converted SPAD values differ from photometric measurements of solvent-extracted chlorophyll by just ~6% on average. PMID:21188527

  3. Arabidopsis thaliana GLN2-Encoded Glutamine Synthetase Is Dual Targeted to Leaf Mitochondria and Chloroplasts

    PubMed Central

    Taira, Masakazu; Valtersson, Ulrika; Burkhardt, Brad; Ludwig, Robert A.

    2004-01-01

    In higher plants, photorespiratory Gly oxidation in leaf mitochondria yields ammonium in large amounts. Mitochondrial ammonium must somehow be recovered as glutamate in chloroplasts. As the first step in that recovery, we report glutamine synthetase (GS) activity in highly purified Arabidopsis thaliana mitochondria isolated from light-adapted leaf tissue. Leaf mitochondrial GS activity is further induced in response to either physiological CO2 limitation or transient darkness. Historically, whether mitochondria are fully competent for oxidative phosphorylation in actively photorespiring leaves has remained uncertain. Here, we report that light-adapted, intact, leaf mitochondria supplied with Gly as sole energy source are fully competent for oxidative phosphorylation. Purified intact mitochondria efficiently use Gly oxidation (as sole energy, NH3, and CO2 source) to drive conversion of l-Orn to l-citrulline, an ATP-dependent process. An A. thaliana genome-wide search for nuclear gene(s) encoding mitochondrial GS activity yielded a single candidate, GLN2. Stably transgenic A. thaliana ecotype Columbia plants expressing a p35S∷GLN2∷green fluorescent protein (GFP) chimeric reporter were constructed. When observed by laser scanning confocal microscopy, leaf mesophyll and epidermal tissue of transgenic plants showed punctate GFP fluorescence that colocalized with mitochondria. In immunoblot experiments, a 41-kD chimeric GLN2∷GFP protein was present in both leaf mitochondria and chloroplasts of these stably transgenic plants. Therefore, the GLN2 gene product, heretofore labeled plastidic GS-2, functions in both leaf mitochondria and chloroplasts to faciliate ammonium recovery during photorespiration. PMID:15273293

  4. Regeneration from leaf protoplasts of Arabidopsis thaliana ecotype estland.

    PubMed

    Gandhi, R; Khurana, P

    2001-07-01

    Protoplasts (2 x 10(7)/g fresh wt) were isolated from leaves of A. thaliana ecotype estland, with a viability of more than 90%. Protoplasts cultured in calcium alginate beads or layers showed division while culture in liquid or agarose beads failed to elicit any division. Effect of culture density showed highest frequency of division occurring at 5 x 10(5) while no division was seen when cultured at a density of 5 x 10(4). Culture in MS medium resulted in higher division frequency and better sustenance of microcolonies as compared to B5 medium. Under optimized conditions, macrocolonies were formed at a frequency of 1.8%. Shoot regeneration was seen in 50% of microcalli transferred to shoot induction medium for regeneration. Shoots were rooted and plantlets transferred to pots. The plants produced flowers and were fertile. PMID:12019766

  5. A Journey Through a Leaf: Phenomics Analysis of Leaf Growth in Arabidopsis thaliana

    PubMed Central

    Vanhaeren, Hannes; Gonzalez, Nathalie; Inzé, Dirk

    2015-01-01

    In Arabidopsis, leaves contribute to the largest part of the aboveground biomass. In these organs, light is captured and converted into chemical energy, which plants use to grow and complete their life cycle. Leaves emerge as a small pool of cells at the vegetative shoot apical meristem and develop into planar, complex organs through different interconnected cellular events. Over the last decade, numerous phenotyping techniques have been developed to visualize and quantify leaf size and growth, leading to the identification of numerous genes that contribute to the final size of leaves. In this review, we will start at the Arabidopsis rosette level and gradually zoom in from a macroscopic view on leaf growth to a microscopic and molecular view. Along this journey, we describe different techniques that have been key to identify important events during leaf development and discuss approaches that will further help unraveling the complex cellular and molecular mechanisms that underlie leaf growth. PMID:26217168

  6. The relationship between leaf area growth and biomass accumulation in Arabidopsis thaliana

    SciTech Connect

    Weraduwage, Sarathi M.; Chen, Jin; Anozie, Fransisca C.; Morales, Alejandro; Weise, Sean E.; Sharkey, Thomas D.

    2015-04-09

    Leaf area growth determines the light interception capacity of a crop and is often used as a surrogate for plant growth in high-throughput phenotyping systems. The relationship between leaf area growth and growth in terms of mass will depend on how carbon is partitioned among new leaf area, leaf mass, root mass, reproduction, and respiration. A model of leaf area growth in terms of photosynthetic rate and carbon partitioning to different plant organs was developed and tested with Arabidopsis thaliana L. Heynh. ecotype Columbia (Col-0) and a mutant line, gigantea-2 (gi-2), which develops very large rosettes. Data obtained from growth analysis and gas exchange measurements was used to train a genetic programming algorithm to parameterize and test the above model. The relationship between leaf area and plant biomass was found to be non-linear and variable depending on carbon partitioning. The model output was sensitive to the rate of photosynthesis but more sensitive to the amount of carbon partitioned to growing thicker leaves. The large rosette size of gi-2 relative to that of Col-0 resulted from relatively small differences in partitioning to new leaf area vs. leaf thickness.

  7. The relationship between leaf area growth and biomass accumulation in Arabidopsis thaliana

    DOE PAGESBeta

    Weraduwage, Sarathi M.; Chen, Jin; Anozie, Fransisca C.; Morales, Alejandro; Weise, Sean E.; Sharkey, Thomas D.

    2015-04-09

    Leaf area growth determines the light interception capacity of a crop and is often used as a surrogate for plant growth in high-throughput phenotyping systems. The relationship between leaf area growth and growth in terms of mass will depend on how carbon is partitioned among new leaf area, leaf mass, root mass, reproduction, and respiration. A model of leaf area growth in terms of photosynthetic rate and carbon partitioning to different plant organs was developed and tested with Arabidopsis thaliana L. Heynh. ecotype Columbia (Col-0) and a mutant line, gigantea-2 (gi-2), which develops very large rosettes. Data obtained from growthmore » analysis and gas exchange measurements was used to train a genetic programming algorithm to parameterize and test the above model. The relationship between leaf area and plant biomass was found to be non-linear and variable depending on carbon partitioning. The model output was sensitive to the rate of photosynthesis but more sensitive to the amount of carbon partitioned to growing thicker leaves. The large rosette size of gi-2 relative to that of Col-0 resulted from relatively small differences in partitioning to new leaf area vs. leaf thickness.« less

  8. The relationship between leaf area growth and biomass accumulation in Arabidopsis thaliana

    PubMed Central

    Weraduwage, Sarathi M.; Chen, Jin; Anozie, Fransisca C.; Morales, Alejandro; Weise, Sean E.; Sharkey, Thomas D.

    2015-01-01

    Leaf area growth determines the light interception capacity of a crop and is often used as a surrogate for plant growth in high-throughput phenotyping systems. The relationship between leaf area growth and growth in terms of mass will depend on how carbon is partitioned among new leaf area, leaf mass, root mass, reproduction, and respiration. A model of leaf area growth in terms of photosynthetic rate and carbon partitioning to different plant organs was developed and tested with Arabidopsis thaliana L. Heynh. ecotype Columbia (Col-0) and a mutant line, gigantea-2 (gi-2), which develops very large rosettes. Data obtained from growth analysis and gas exchange measurements was used to train a genetic programming algorithm to parameterize and test the above model. The relationship between leaf area and plant biomass was found to be non-linear and variable depending on carbon partitioning. The model output was sensitive to the rate of photosynthesis but more sensitive to the amount of carbon partitioned to growing thicker leaves. The large rosette size of gi-2 relative to that of Col-0 resulted from relatively small differences in partitioning to new leaf area vs. leaf thickness. PMID:25914696

  9. The relationship between leaf area growth and biomass accumulation in Arabidopsis thaliana.

    PubMed

    Weraduwage, Sarathi M; Chen, Jin; Anozie, Fransisca C; Morales, Alejandro; Weise, Sean E; Sharkey, Thomas D

    2015-01-01

    Leaf area growth determines the light interception capacity of a crop and is often used as a surrogate for plant growth in high-throughput phenotyping systems. The relationship between leaf area growth and growth in terms of mass will depend on how carbon is partitioned among new leaf area, leaf mass, root mass, reproduction, and respiration. A model of leaf area growth in terms of photosynthetic rate and carbon partitioning to different plant organs was developed and tested with Arabidopsis thaliana L. Heynh. ecotype Columbia (Col-0) and a mutant line, gigantea-2 (gi-2), which develops very large rosettes. Data obtained from growth analysis and gas exchange measurements was used to train a genetic programming algorithm to parameterize and test the above model. The relationship between leaf area and plant biomass was found to be non-linear and variable depending on carbon partitioning. The model output was sensitive to the rate of photosynthesis but more sensitive to the amount of carbon partitioned to growing thicker leaves. The large rosette size of gi-2 relative to that of Col-0 resulted from relatively small differences in partitioning to new leaf area vs. leaf thickness. PMID:25914696

  10. Individual Leaf Development in Arabidopsis thaliana: a Stable Thermal‐time‐based Programme

    PubMed Central

    GRANIER, CHRISTINE; MASSONNET, CATHERINE; TURC, OLIVIER; MULLER, BERTRAND; CHENU, KARINE; TARDIEU, FRANÇOIS

    2002-01-01

    In crop species, the impact of temperature on plant development is classically modelled using thermal time. We examined whether this method could be used in a non‐crop species, Arabidopsis thaliana, to analyse the response to temperature of leaf initiation rate and of the development of two leaves of the rosette. The results confirmed the large plant‐to‐plant variability in the studied isogenic line of the Columbia ecotype: 100‐fold differences in leaf area among plants sown on the same date were commonly observed at a given date. These differences disappeared in mature leaves, suggesting that they were due to a variability in plant developmental stage. The whole population could therefore be represented by any group of synchronous plants labelled at the two‐leaf stage and followed during their development. Leaf initiation rate, duration of leaf expansion and maximal relative leaf expansion rate varied considerably among experiments performed at different temperatures (from 6 to 26 °C) but they were linearly related to temperature in the range 6–26 °C, with a common x‐intercept of 3 °C. Expressing time in thermal time with a threshold temperature of 3 °C unified the time courses of leaf initiation and of individual leaf development for plants grown at different temperatures and experimental conditions. The two leaves studied (leaf 2 and leaf 6) had a two‐phase development, with an exponential phase followed by a phase with decreasing relative elongation rate. Both phases had constant durations for a given leaf position if expressed in thermal time. Changes in temperature caused changes in both the rate of development and in the expansion rate which mutually compensated such that they had no consequence on leaf area at a given thermal time. The resulting model of leaf development was applied to ten experiments carried out in a glasshouse or in a growth chamber, with plants grown in soil or hydroponically. Because it predicts accurately the stage

  11. Influence of atmospheric oxygen on leaf structure and starch deposition in Arabidopsis thaliana

    NASA Technical Reports Server (NTRS)

    Ramonell, K. M.; Kuang, A.; Porterfield, D. M.; Crispi, M. L.; Xiao, Y.; McClure, G.; Musgrave, M. E.

    2001-01-01

    Plant culture in oxygen concentrations below ambient is known to stimulate vegetative growth, but apart from reports on increased leaf number and weight, little is known about development at subambient oxygen concentrations. Arabidopsis thaliana (L.) Heynh. (cv. Columbia) plants were grown full term in pre-mixed atmospheres with oxygen partial pressures of 2.5, 5.1, 10.1, 16.2, and 21.3 kPa O2, 0.035 kPa CO2 and the balance nitrogen under continuous light. Fully expanded leaves were harvested and processed for light and transmission electron microscopy or for starch quantification. Growth in subambient oxygen concentrations caused changes in leaf anatomy (increased thickness, stomatal density and starch content) that have also been described for plants grown under carbon dioxide enrichment. However, at the lowest oxygen treatment (2.5 kPa), developmental changes occurred that could not be explained by changes in carbon budget caused by suppressed photorespiration, resulting in very thick leaves and a dwarf morphology. This study establishes the leaf parameters that change during growth under low O2, and identifies the lower concentration at which O2 limitation on transport and biosynthetic pathways detrimentally affects leaf development. Grant numbers: NAG5-3756, NAG2-1020, NAG2-1375.

  12. Ectopic divisions in vascular and ground tissues of Arabidopsis thaliana result in distinct leaf venation defects

    PubMed Central

    Wenzel, C. L.

    2012-01-01

    Leaf venation patterns vary considerably between species and between leaves within a species. A mechanism based on canalization of auxin transport has been suggested as the means by which plastic yet organized venation patterns are generated. This study assessed the plasticity of Arabidopsis thaliana leaf venation in response to ectopic ground or procambial cell divisions and auxin transport inhibition (ATI). Ectopic ground cell divisions resulted in vascular fragments between major veins, whereas ectopic procambial cell divisions resulted in additional, abnormal vessels along major veins, with more severely perturbed lines forming incomplete secondary and higher-order venation. These responses imply limited vascular plasticity in response to unscheduled cell divisions. Surprisingly, a combination of ectopic ground cell divisions and ATI resulted in massive vascular overgrowth. It is hypothesized that the vascular overproduction in auxin transport-inhibited wild-type leaves is limited by simultaneous differentiation of ground cells into mesophyll cells. Ectopic ground cell divisions may negate this effect by providing undifferentiated ground cells that respond to accumulated auxin by differentiation into vascular cells. PMID:22936832

  13. Somatic embryogenesis in cultured immature zygotic embryos and leaf protoplasts of Arabidopsis thaliana ecotypes.

    PubMed

    Luo, Y; Koop, H U

    1997-01-01

    Immature zygotic embryos of six ecotypes (Nd-0, Ler, C24, Col-0, Nossen, Ws-2) of Arabidopsis thaliana (L.) Heynh. were cultured in vitro. The same ecotypes, except Nossen, were used for studies on leaf protoplast culture. Experimental conditions for the induction of somatic embryos were established in both culture systems. In the case of immature zygotic embryos, the parameters investigated were the influence of developmental stage of the explant, the ecotypes used, and various concentrations and combinations of growth regulatory substances (phytohormones). In the ecotype Ler, structures were discovered which were very similar to those found in the early stages of zygotic embryo-genesis: globular structures at the end of a suspensor-like single file of cells were frequently observed. In the case of leaf protoplasts, high efficiencies of colony formation and plant regeneration occurred in Ws-2 and C24. A novel type of cell division pattern was found in Col-0 and C24, again highly reminiscent of the early division patterns in zygotic embryos. Similarities and differences between zygotic and somatic embryogenesis are discussed. PMID:9232908

  14. Testing models for the leaf economics spectrum with leaf and whole-plant traits in Arabidopsis thaliana

    PubMed Central

    Blonder, Benjamin; Vasseur, François; Violle, Cyrille; Shipley, Bill; Enquist, Brian J.; Vile, Denis

    2015-01-01

    The leaf economics spectrum (LES) describes strong relationships between multiple functional leaf traits that determine resource fluxes in vascular plants. Five models have been proposed to explain these patterns: two based on patterns of structural allocation, two on venation networks and one on resource allocation to cell walls and cell contents. Here we test these models using data for leaf and whole-plant functional traits. We use structural equation modelling applied to multiple ecotypes, recombinant inbred lines, near isogenic lines and vascular patterning mutants of Arabidopsis thaliana that express LES trait variation. We show that a wide variation in multiple functional traits recapitulates the LES at the whole-plant scale. The Wright et al. (2004) model and the Blonder et al. (2013) venation network model cannot be rejected by data, while two simple models and the Shipley et al. (2006) allocation model are rejected. Venation networks remain a key hypothesis for the origin of the LES, but simpler explanations also cannot be ruled out. PMID:25957316

  15. A geographic cline in leaf salicylic acid with increasing elevation in Arabidopsis thaliana.

    PubMed

    Zhang, Nana; Tonsor, Stephen J; Traw, M Brian

    2015-01-01

    Salicylic acid (SA) occupies a key role as a hormone central to both plant resistance to bacterial pathogens and tolerance of abiotic stresses. Plants at high elevation experience colder temperatures and elevated UV levels. While it has been predicted that SA concentrations will be higher in plants from high elevation populations, few studies have addressed this question. Here, we asked how concentrations of SA vary in natural populations of Arabidopsis thaliana collected across an elevational gradient on the Iberian Peninsula. In a series of common garden experiments, we found that constitutive SA concentrations were highest in genotypes from the low elevation populations. This result was in the opposite direction from our prediction and is an exception to the general finding that phenolic compounds increase with increasing elevation. These data suggest that high constitutive SA is not associated with resistance to cold temperatures in these plants. Furthermore, we also found that leaf constitutive camalexin concentrations, an important defense against some bacterial and fungal enemies, were highest in the low elevation populations, suggesting that pathogen pressures may be important. Further examination of this elevational cline will likely provide additional insights into the interplay between phenolic compounds and biotic and abiotic stress. PMID:25875692

  16. A geographic cline in leaf salicylic acid with increasing elevation in Arabidopsis thaliana

    PubMed Central

    Zhang, Nana; Tonsor, Stephen J; Traw, M Brian

    2015-01-01

    Salicylic acid (SA) occupies a key role as a hormone central to both plant resistance to bacterial pathogens and tolerance of abiotic stresses. Plants at high elevation experience colder temperatures and elevated UV levels. While it has been predicted that SA concentrations will be higher in plants from high elevation populations, few studies have addressed this question. Here, we asked how concentrations of SA vary in natural populations of Arabidopsis thaliana collected across an elevational gradient on the Iberian Peninsula. In a series of common garden experiments, we found that constitutive SA concentrations were highest in genotypes from the low elevation populations. This result was in the opposite direction from our prediction and is an exception to the general finding that phenolic compounds increase with increasing elevation. These data suggest that high constitutive SA is not associated with resistance to cold temperatures in these plants. Furthermore, we also found that leaf constitutive camalexin concentrations, an important defense against some bacterial and fungal enemies, were highest in the low elevation populations, suggesting that pathogen pressures may be important. Further examination of this elevational cline will likely provide additional insights into the interplay between phenolic compounds and biotic and abiotic stress. PMID:25875692

  17. Development-related PcG target in the apex 4 controls leaf margin architecture in Arabidopsis thaliana.

    PubMed

    Engelhorn, Julia; Reimer, Julia J; Leuz, Iris; Göbel, Ulrike; Huettel, Bruno; Farrona, Sara; Turck, Franziska

    2012-07-01

    In a reverse genetics screen based on a group of genes enriched for development-related Polycomb group targets in the apex (DPAs), we isolated DPA4 as a novel regulator of leaf margin shape. T-DNA insertion lines in the DPA4 locus display enhanced leaf margin serrations and enlarged petals, whereas overexpression of DPA4 results in smooth margins. DPA4 encodes a putative RAV (Related to ABI3/VP1) transcriptional repressor and is expressed in the lateral organ boundary region and in the sinus of leaf serrations. DPA4 expression domains overlap with those of the known leaf shape regulator CUP-SHAPED COTYLEDON 2 (CUC2) and we provide evidence that DPA4 negatively regulates CUC2 expression independently of MIR164A, an established regulator of CUC2. Taken together, the data suggest DPA4 as a newly identified player in the signalling network that controls leaf serrations in Arabidopsis thaliana. PMID:22675210

  18. Higher peroxidase activity, leaf nutrient contents and carbon isotope composition changes in Arabidopsis thaliana are related to rutin stress.

    PubMed

    Hussain, M Iftikhar; Reigosa, Manuel J

    2014-09-15

    Rutin, a plant secondary metabolite that is used in cosmetics and food additive and has known medicinal properties, protects plants from UV-B radiation and diseases. Rutin has been suggested to have potential in weed management, but its mode of action at physiological level is unknown. Here, we report the biochemical, physiological and oxidative response of Arabidopsis thaliana to rutin at micromolar concentrations. It was found that fresh weight; leaf mineral contents (nitrogen, sodium, potassium, copper and aluminum) were decreased following 1 week exposure to rutin. Arabidopsis roots generate significant amounts of reactive oxygen species after rutin treatment, consequently increasing membrane lipid peroxidation, decreasing leaf Ca(2+), Mg(2+), Zn(2+), Fe(2+) contents and losing root viability. Carbon isotope composition in A. thaliana leaves was less negative after rutin application than the control. Carbon isotope discrimination values were decreased following rutin treatment, with the highest reduction compared to the control at 750μM rutin. Rutin also inhibited the ratio of CO2 from leaf to air (ci/ca) at all concentrations. Total protein contents in A. thaliana leaves were decreased following rutin treatment. It was concluded carbon isotope discrimination coincided with protein degradation, increase lipid peroxidation and a decrease in ci/ca values may be the primary action site of rutin. The present results suggest that rutin possesses allelopathic potential and could be used as a candidate to develop environment friendly natural herbicide. PMID:25046753

  19. Leaf biomechanical properties in Arabidopsis thaliana polysaccharide mutants affect drought survival.

    PubMed

    Balsamo, Ronald; Boak, Merewyn; Nagle, Kayla; Peethambaran, Bela; Layton, Bradley

    2015-11-26

    Individual sugars are the building blocks of cell wall polysaccharides, which in turn comprise a plant׳s overall architectural structure. But which sugars play the most prominent role in maintaining a plant׳s mechanical stability during large cellular deformations induced by drought? We investigated the individual contributions of several genes that are involved in the synthesis of monosaccharides which are important for cell wall structure. We then measured drought tolerance and mechanical integrity during simulated drought in Arabidopsis thaliana. To assess mechanical properties, we designed a small-scale tensile tester for measuring failure strain, ultimate tensile stress, work to failure, toughness, and elastic modulus of 6-week-old leaves in both hydrated and drought-simulated states. Col-0 mutants used in this study include those deficient in lignin, cellulose, components of hemicellulose such as xylose and fucose, the pectic components arabinose and rhamnose, as well as mutants with enhanced arabinose and total pectin content. We found that drought tolerance is correlated to the mechanical and architectural stability of leaves as they experience dehydration. Of the mutants, S096418 with mutations for reduced xylose and galactose was the least drought tolerant, while the arabinose-altered CS8578 mutants were the least affected by water loss. There were also notable correlations between drought tolerance and mechanical properties in the diminished rhamnose mutant, CS8575 and the dehydrogenase-disrupted S120106. Our findings suggest that components of hemicellulose and pectins affect leaf biomechanical properties and may play an important role in the ability of this model system to survive drought. PMID:26520913

  20. Effect of BPA on the germination, root development, seedling growth and leaf differentiation under different light conditions in Arabidopsis thaliana.

    PubMed

    Pan, Wen-Juan; Xiong, Can; Wua, Qiu-Ping; Liu, Jin-Xia; Liao, Hong-Mei; Chen, Wei; Liu, Yong-Sheng; Zheng, Lei

    2013-11-01

    Bisphenol A (BPA) is a well-known environmental toxic substance, which exerts unfavorable effects through endocrine disruptor (ER)-dependent and ER-independent mechanisms to threaten ecological systems seriously. BPA may also interact with other environmental factors, such as light and heavy metals, to have a synergetic effect in plants. However, there is little data concerning the toxic effect of BPA on the primary producers-plants and its possible interaction with light-dependent response. Here, the effects of BPA on germination, fresh weight, tap root length, and leaf differentiation were studied in Arabidopsis thaliana under different parts of light spectrum (dark, red, yellow, green, blue, and white light). Our results showed that low-dose BPA (1.0, 5.0 µM) caused an increase in the fresh weight, the tap root length and the lateral root formation of A. thaliana seedlings, while high-dose BPA (10.0, 25.0 µM) show an inhibition effect in a dose-dependent manner. Unlike karrikins, the effects of BPA on germination fresh weight and tap roots length under various light conditions are similar, which imply that BPA has no notable role in priming light response in germination and early seedling growth in A. thaliana. Meanwhile, BPA exposure influences the differentiation of A. thaliana leaf blade significantly in a light-dependent manner with little to no effect in dark and clear effect under red illumination. PMID:24206833

  1. Dynamics of Jasmonate Metabolism upon Flowering and across Leaf Stress Responses in Arabidopsis thaliana

    PubMed Central

    Widemann, Emilie; Smirnova, Ekaterina; Aubert, Yann; Miesch, Laurence; Heitz, Thierry

    2016-01-01

    The jasmonic acid (JA) signaling pathway plays important roles in adaptation of plants to environmental cues and in specific steps of their development, particularly in reproduction. Recent advances in metabolic studies have highlighted intricate mechanisms that govern enzymatic conversions within the jasmonate family. Here we analyzed jasmonate profile changes upon Arabidopsis thaliana flower development and investigated the contribution of catabolic pathways that were known to turnover the active hormonal compound jasmonoyl-isoleucine (JA-Ile) upon leaf stress. We report a rapid decline of JA-Ile upon flower opening, concomitant with the massive accumulation of its most oxidized catabolite, 12COOH-JA-Ile. Detailed genetic analysis identified CYP94C1 as the major player in this process. CYP94C1 is one out of three characterized cytochrome P450 enzymes that define an oxidative JA-Ile turnover pathway, besides a second, hydrolytic pathway represented by the amido-hydrolases IAR3 and ILL6. Expression studies combined with reporter gene analysis revealed the dominant expression of CYP94C1 in mature anthers, consistent with the established role of JA signaling in male fertility. Significant CYP94B1 expression was also evidenced in stamen filaments, but surprisingly, CYP94B1 deficiency was not associated with significant changes in JA profiles. Finally, we compared global flower JA profiles with those previously reported in leaves reacting to mechanical wounding or submitted to infection by the necrotrophic fungus Botrytis cinerea. These comparisons revealed distinct dynamics of JA accumulation and conversions in these three biological systems. Leaf injury boosts a strong and transient JA and JA-Ile accumulation that evolves rapidly into a profile dominated by ω-oxidized and/or Ile-conjugated derivatives. In contrast, B. cinerea-infected leaves contain mostly unconjugated jasmonates, about half of this content being ω-oxidized. Finally, developing flowers present an

  2. Distinct palisade tissue development processes promoted by leaf autonomous signalling and long-distance signalling in Arabidopsis thaliana.

    PubMed

    Munekage, Yuri Nakajima; Inoue, Shio; Yoneda, Yuki; Yokota, Akiho

    2015-06-01

    Plants develop palisade tissue consisting of cylindrical mesophyll cells located at the adaxial side of leaves in response to high light. To understand high light signalling in palisade tissue development, we investigated leaf autonomous and long-distance signal responses of palisade tissue development using Arabidopsis thaliana. Illumination of a developing leaf with high light induced cell height elongation, whereas illumination of mature leaves with high light increased cell density and suppressed cell width expansion in palisade tissue of new leaves. Examination using phototropin1 phototropin2 showed that blue light signalling mediated by phototropins was involved in cell height elongation of the leaf autonomous response rather than the cell density increase induced by long-distance signalling. Hydrogen peroxide treatment induced cylindrical palisade tissue cell formation in both a leaf autonomous and long-distance manner, suggesting involvement of oxidative signals. Although constitutive expression of transcription factors involved in systemic-acquired acclimation to excess light, ZAT10 and ZAT12, induced cylindrical palisade tissue cell formation, knockout of these genes did not affect cylindrical palisade tissue cell formation. We conclude that two distinct signalling pathways - leaf autonomous signalling mostly dependent on blue light signalling and long-distance signalling from mature leaves that sense high light and oxidative stress - control palisade tissue development in A. thaliana. PMID:25293694

  3. Sphingolipids in the Root Play an Important Role in Regulating the Leaf Ionome in Arabidopsis thaliana[W][OA

    PubMed Central

    Chao, Dai-Yin; Gable, Kenneth; Chen, Ming; Baxter, Ivan; Dietrich, Charles R.; Cahoon, Edgar B.; Guerinot, Mary Lou; Lahner, Brett; Lü, Shiyou; Markham, Jonathan E.; Morrissey, Joe; Han, Gongshe; Gupta, Sita D.; Harmon, Jeffrey M.; Jaworski, Jan G.; Dunn, Teresa M.; Salt, David E.

    2011-01-01

    Sphingolipid synthesis is initiated by condensation of Ser with palmitoyl-CoA producing 3-ketodihydrosphinganine (3-KDS), which is reduced by a 3-KDS reductase to dihydrosphinganine. Ser palmitoyltransferase is essential for plant viability. Arabidopsis thaliana contains two genes (At3g06060/TSC10A and At5g19200/TSC10B) encoding proteins with significant similarity to the yeast 3-KDS reductase, Tsc10p. Heterologous expression in yeast of either Arabidopsis gene restored 3-KDS reductase activity to the yeast tsc10Δ mutant, confirming both as bona fide 3-KDS reductase genes. Consistent with sphingolipids having essential functions in plants, double mutant progeny lacking both genes were not recovered from crosses of single tsc10A and tsc10B mutants. Although the 3-KDS reductase genes are functionally redundant and ubiquitously expressed in Arabidopsis, 3-KDS reductase activity was reduced to 10% of wild-type levels in the loss-of-function tsc10a mutant, leading to an altered sphingolipid profile. This perturbation of sphingolipid biosynthesis in the Arabidopsis tsc10a mutant leads an altered leaf ionome, including increases in Na, K, and Rb and decreases in Mg, Ca, Fe, and Mo. Reciprocal grafting revealed that these changes in the leaf ionome are driven by the root and are associated with increases in root suberin and alterations in Fe homeostasis. PMID:21421810

  4. Genome-wide association study of Arabidopsis thaliana's leaf microbial community

    PubMed Central

    Horton, Matthew W.; Bodenhausen, Natacha; Beilsmith, Kathleen; Meng, Dazhe; Muegge, Brian D.; Subramanian, Sathish; Vetter, M. Madlen; Vilhjálmsson, Bjarni J.; Nordborg, Magnus; Gordon, Jeffrey I.; Bergelson, Joy

    2014-01-01

    Identifying the factors that influence the outcome of host-microbial interactions is critical to protecting biodiversity, minimizing agricultural losses, and improving human health. A few genes that determine symbiosis or resistance to infectious disease have been identified in model species, but a comprehensive examination of how a host's genotype influences the structure of its microbial community is lacking. Here we report the results of a field experiment with the model plant Arabidopsis thaliana to identify the fungi and bacteria that colonize its leaves and the host loci that influence the microbes’ numbers. The composition of this community differs among accessions of A. thaliana. Genome-wide association studies (GWAS) suggest that plant loci responsible for defense and cell wall integrity affect variation in this community. Furthermore, species richness in the bacterial community is shaped by host genetic variation, notably at loci that also influence the reproduction of viruses, trichome branching and morphogenesis. PMID:25382143

  5. A workflow for mathematical modeling of subcellular metabolic pathways in leaf metabolism of Arabidopsis thaliana

    PubMed Central

    Nägele, Thomas; Weckwerth, Wolfram

    2013-01-01

    During the last decade genome sequencing has experienced a rapid technological development resulting in numerous sequencing projects and applications in life science. In plant molecular biology, the availability of sequence data on whole genomes has enabled the reconstruction of metabolic networks. Enzymatic reactions are predicted by the sequence information. Pathways arise due to the participation of chemical compounds as substrates and products in these reactions. Although several of these comprehensive networks have been reconstructed for the genetic model plant Arabidopsis thaliana, the integration of experimental data is still challenging. Particularly the analysis of subcellular organization of plant cells limits the understanding of regulatory instances in these metabolic networks in vivo. In this study, we develop an approach for the functional integration of experimental high-throughput data into such large-scale networks. We present a subcellular metabolic network model comprising 524 metabolic intermediates and 548 metabolic interactions derived from a total of 2769 reactions. We demonstrate how to link the metabolite covariance matrix of different Arabidopsis thaliana accessions with the subcellular metabolic network model for the inverse calculation of the biochemical Jacobian, finally resulting in the calculation of a matrix which satisfies a Lyaponov equation. In this way, different strategies of metabolite compartmentation and involved reactions were identified in the accessions when exposed to low temperature. PMID:24400018

  6. Magnitude and Timing of Leaf Damage Affect Seed Production in a Natural Population of Arabidopsis thaliana (Brassicaceae)

    PubMed Central

    Akiyama, Reiko; Ågren, Jon

    2012-01-01

    Background The effect of herbivory on plant fitness varies widely. Understanding the causes of this variation is of considerable interest because of its implications for plant population dynamics and trait evolution. We experimentally defoliated the annual herb Arabidopsis thaliana in a natural population in Sweden to test the hypotheses that (a) plant fitness decreases with increasing damage, (b) tolerance to defoliation is lower before flowering than during flowering, and (c) defoliation before flowering reduces number of seeds more strongly than defoliation during flowering, but the opposite is true for effects on seed size. Methodology/Principal Findings In a first experiment, between 0 and 75% of the leaf area was removed in May from plants that flowered or were about to start flowering. In a second experiment, 0, 25%, or 50% of the leaf area was removed from plants on one of two occasions, in mid April when plants were either in the vegetative rosette or bolting stage, or in mid May when plants were flowering. In the first experiment, seed production was negatively related to leaf area removed, and at the highest damage level, also mean seed size was reduced. In the second experiment, removal of 50% of the leaf area reduced seed production by 60% among plants defoliated early in the season at the vegetative rosettes, and by 22% among plants defoliated early in the season at the bolting stage, but did not reduce seed output of plants defoliated one month later. No seasonal shift in the effect of defoliation on seed size was detected. Conclusions/Significance The results show that leaf damage may reduce the fitness of A. thaliana, and suggest that in this population leaf herbivores feeding on plants before flowering should exert stronger selection on defence traits than those feeding on plants during flowering, given similar damage levels. PMID:22276140

  7. Re-evaluating the role of phenolic glycosides and ascorbic acid in ozone scavenging in the leaf apoplast of Arabidopsis thaliana L

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To determine if membrane-bound G-proteins are involved in the regulation of defense responses against ozone in the leaf apoplast, the apoplastic concentrations of ascorbic acid and phenolic glycosides in Arabidopsis thaliana L. lines with null mutations in the alpha- and beta-subunits were compared ...

  8. ELS1, a novel MATE transporter related to leaf senescence and iron homeostasis in Arabidopsis thaliana.

    PubMed

    Wang, Zhenyu; Qian, Chongzhen; Guo, Xiaochun; Liu, Erlong; Mao, Kaili; Mu, Changjun; Chen, Ni; Zhang, Wei; Liu, Heng

    2016-08-01

    The multidrug and toxic compound extrusion (MATE) transporters mediate the coupled exchange of organic substrates and monovalent cations have been recently implicated in various plant biological activities. In this work, we isolated a dominant mutant from an Arabidopsis activation-tagging mutant pool. This mutant exhibits pleiotropic phenotype including early flowering, dwarf and bushy architecture, minified lateral organs and early leaf senescence, and is therefore designated early leaf senescence 1-Dominaint (els1-D). Genotyping assays showed that els1-D is a gain-of-function mutant of a novel MATE transporter gene, ELS1, which encodes a close homolog of the previously reported ADP1, BCD1 and DTX50. Further investigations revealed that the overexpression of ELS1 reduces iron content in els1-D, and the accelerated senescence of the detached els1-D leaves can be recovered by exogenous iron supply. In addition, we also found that ELS1 is an iron responsive gene. Based on these findings, we proposed that ELS1 is related to leaf senescence and iron homeostasis in Arabidopsis. PMID:27233612

  9. Leaf water dynamics of Arabidopsis thaliana monitored in-vivo using terahertz time-domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Castro-Camus, E.; Palomar, M.; Covarrubias, A. A.

    2013-10-01

    The declining water availability for agriculture is becoming problematic for many countries. Therefore the study of plants under water restriction is acquiring extraordinary importance. Botanists currently follow the dehydration of plants comparing the fresh and dry weight of excised organs, or measuring their osmotic or water potentials; these are destructive methods inappropriate for in-vivo determination of plants' hydration dynamics. Water is opaque in the terahertz band, while dehydrated biological tissues are partially transparent. We used terahertz spectroscopy to study the water dynamics of Arabidopsis thaliana by comparing the dehydration kinetics of leaves from plants under well-irrigated and water deficit conditions. We also present measurements of the effect of dark-light cycles and abscisic acid on its water dynamics. The measurements we present provide a new perspective on the water dynamics of plants under different external stimuli and confirm that terahertz can be an excellent non-contact probe of in-vivo tissue hydration.

  10. Myrosin Cell Development Is Regulated by Endocytosis Machinery and PIN1 Polarity in Leaf Primordia of Arabidopsis thaliana[W

    PubMed Central

    Shirakawa, Makoto; Ueda, Haruko; Shimada, Tomoo; Kohchi, Takayuki; Hara-Nishimura, Ikuko

    2014-01-01

    Myrosin cells, which accumulate myrosinase to produce toxic compounds when they are ruptured by herbivores, form specifically along leaf veins in Arabidopsis thaliana. However, the mechanism underlying this pattern formation is unknown. Here, we show that myrosin cell development requires the endocytosis-mediated polar localization of the auxin-efflux carrier PIN1 in leaf primordia. Defects in the endocytic/vacuolar SNAREs (syp22 and syp22 vti11) enhanced myrosin cell development. The syp22 phenotype was rescued by expressing SYP22 under the control of the PIN1 promoter. Additionally, myrosin cell development was enhanced either by lacking the activator of endocytic/vacuolar RAB5 GTPase (VPS9A) or by PIN1 promoter-driven expression of a dominant-negative form of RAB5 GTPase (ARA7). By contrast, myrosin cell development was not affected by deficiencies of vacuolar trafficking factors, including the vacuolar sorting receptor VSR1 and the retromer components VPS29 and VPS35, suggesting that endocytic pathway rather than vacuolar trafficking pathway is important for myrosin cell development. The phosphomimic PIN1 variant (PIN1-Asp), which is unable to be polarized, caused myrosin cells to form not only along leaf vein but also in the intervein leaf area. We propose that Brassicales plants might arrange myrosin cells near vascular cells in order to protect the flux of nutrients and water via polar PIN1 localization. PMID:25428982

  11. Leaf Age-Dependent Photoprotective and Antioxidative Response Mechanisms to Paraquat-Induced Oxidative Stress in Arabidopsis thaliana.

    PubMed

    Moustaka, Julietta; Tanou, Georgia; Adamakis, Ioannis-Dimosthenis; Eleftheriou, Eleftherios P; Moustakas, Michael

    2015-01-01

    Exposure of Arabidopsis thaliana young and mature leaves to the herbicide paraquat (Pq) resulted in a localized increase of hydrogen peroxide (H2O2) in the leaf veins and the neighboring mesophyll cells, but this increase was not similar in the two leaf types. Increased H2O2 production was concomitant with closed reaction centers (qP). Thirty min after Pq exposure despite the induction of the photoprotective mechanism of non-photochemical quenching (NPQ) in mature leaves, H2O2 production was lower in young leaves mainly due to the higher increase activity of ascorbate peroxidase (APX). Later, 60 min after Pq exposure, the total antioxidant capacity of young leaves was not sufficient to scavenge the excess reactive oxygen species (ROS) that were formed, and thus, a higher H2O2 accumulation in young leaves occurred. The energy allocation of absorbed light in photosystem II (PSII) suggests the existence of a differential photoprotective regulatory mechanism in the two leaf types to the time-course Pq exposure accompanied by differential antioxidant protection mechanisms. It is concluded that tolerance to Pq-induced oxidative stress is related to the redox state of quinone A (QA). PMID:26096005

  12. Leaf Age-Dependent Photoprotective and Antioxidative Response Mechanisms to Paraquat-Induced Oxidative Stress in Arabidopsis thaliana

    PubMed Central

    Moustaka, Julietta; Tanou, Georgia; Adamakis, Ioannis-Dimosthenis; Eleftheriou, Eleftherios P.; Moustakas, Michael

    2015-01-01

    Exposure of Arabidopsis thaliana young and mature leaves to the herbicide paraquat (Pq) resulted in a localized increase of hydrogen peroxide (H2O2) in the leaf veins and the neighboring mesophyll cells, but this increase was not similar in the two leaf types. Increased H2O2 production was concomitant with closed reaction centers (qP). Thirty min after Pq exposure despite the induction of the photoprotective mechanism of non-photochemical quenching (NPQ) in mature leaves, H2O2 production was lower in young leaves mainly due to the higher increase activity of ascorbate peroxidase (APX). Later, 60 min after Pq exposure, the total antioxidant capacity of young leaves was not sufficient to scavenge the excess reactive oxygen species (ROS) that were formed, and thus, a higher H2O2 accumulation in young leaves occurred. The energy allocation of absorbed light in photosystem II (PSII) suggests the existence of a differential photoprotective regulatory mechanism in the two leaf types to the time-course Pq exposure accompanied by differential antioxidant protection mechanisms. It is concluded that tolerance to Pq-induced oxidative stress is related to the redox state of quinone A (QA). PMID:26096005

  13. Impacts of high ATP supply from chloroplasts and mitochondria on the leaf metabolism of Arabidopsis thaliana

    PubMed Central

    Liang, Chao; Zhang, Youjun; Cheng, Shifeng; Osorio, Sonia; Sun, Yuzhe; Fernie, Alisdair R.; Cheung, C. Y. M.; Lim, Boon L.

    2015-01-01

    Chloroplasts and mitochondria are the major ATP producing organelles in plant leaves. Arabidopsis thaliana purple acid phosphatase 2 (AtPAP2) is a phosphatase dually targeted to the outer membranes of both organelles and it plays a role in the import of selected nuclear-encoded proteins into these two organelles. Overexpression (OE) of AtPAP2 in A. thaliana accelerates plant growth and promotes flowering, seed yield, and biomass at maturity. Measurement of ADP/ATP/NADP+/NADPH contents in the leaves of 20-day-old OE and wild-type (WT) lines at the end of night and at 1 and 8 h following illumination in a 16/8 h photoperiod revealed that the ATP levels and ATP/NADPH ratios were significantly increased in the OE line at all three time points. The AtPAP2 OE line is therefore a good model to investigate the impact of high energy on the global molecular status of Arabidopsis. In this study, transcriptome, proteome, and metabolome profiles of the high ATP transgenic line were examined and compared with those of WT plants. A comparison of OE and WT at the end of the night provide valuable information on the impact of higher ATP output from mitochondria on plant physiology, as mitochondrial respiration is the major source of ATP in the dark in leaves. Similarly, comparison of OE and WT following illumination will provide information on the impact of higher energy output from chloroplasts on plant physiology. OE of AtPAP2 was found to significantly affect the transcript and protein abundances of genes encoded by the two organellar genomes. For example, the protein abundances of many ribosomal proteins encoded by the chloroplast genome were higher in the AtPAP2 OE line under both light and dark conditions, while the protein abundances of multiple components of the photosynthetic complexes were lower. RNA-seq data also showed that the transcription of the mitochondrial genome is greatly affected by the availability of energy. These data reflect that the transcription and

  14. Shotgun Proteomic Analysis of Arabidopsis thaliana Leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two shotgun tandem mass spectrometry proteomics approaches, Multidimensional Protein Identification Technology (MudPIT) and 1D-Gel-LC-MS/MS, were used to identify Arabidopsis thaliana leaf proteins. These methods utilize different protein/peptide separation strategies. Detergents not compatible wit...

  15. Verticillium longisporum Infection Affects the Leaf Apoplastic Proteome, Metabolome, and Cell Wall Properties in Arabidopsis thaliana

    PubMed Central

    Floerl, Saskia; Majcherczyk, Andrzej; Possienke, Mareike; Feussner, Kirstin; Tappe, Hella; Gatz, Christiane; Feussner, Ivo; Kües, Ursula; Polle, Andrea

    2012-01-01

    Verticillium longisporum (VL) is one of the most devastating diseases in important oil crops from the family of Brassicaceae. The fungus resides for much time of its life cycle in the extracellular fluid of the vascular system, where it cannot be controlled by conventional fungicides. To obtain insights into the biology of VL-plant interaction in the apoplast, the secretome consisting of the extracellular proteome and metabolome as well as cell wall properties were studied in the model Brassicaceae, Arabidopsis thaliana. VL infection resulted in increased production of cell wall material with an altered composition of carbohydrate polymers and increased lignification. The abundance of several hundred soluble metabolites changed in the apoplast of VL-infected plants including signalling and defence compounds such as glycosides of salicylic acid, lignans and dihydroxybenzoic acid as well as oxylipins. The extracellular proteome of healthy leaves was enriched in antifungal proteins. VL caused specific increases in six apoplast proteins (three peroxidases PRX52, PRX34, P37, serine carboxypeptidase SCPL20, α-galactosidase AGAL2 and a germin-like protein GLP3), which have functions in defence and cell wall modification. The abundance of a lectin-like, chitin-inducible protein (CILLP) was reduced. Since the transcript levels of most of the induced proteins were not elevated until late infection time points (>20 dpi), whereas those of CILLP and GLP3 were reduced at earlier time points, our results may suggest that VL enhances its virulence by rapid down-regulation and delay of induction of plant defence genes. PMID:22363647

  16. Verticillium longisporum infection affects the leaf apoplastic proteome, metabolome, and cell wall properties in Arabidopsis thaliana.

    PubMed

    Floerl, Saskia; Majcherczyk, Andrzej; Possienke, Mareike; Feussner, Kirstin; Tappe, Hella; Gatz, Christiane; Feussner, Ivo; Kües, Ursula; Polle, Andrea

    2012-01-01

    Verticillium longisporum (VL) is one of the most devastating diseases in important oil crops from the family of Brassicaceae. The fungus resides for much time of its life cycle in the extracellular fluid of the vascular system, where it cannot be controlled by conventional fungicides. To obtain insights into the biology of VL-plant interaction in the apoplast, the secretome consisting of the extracellular proteome and metabolome as well as cell wall properties were studied in the model Brassicaceae, Arabidopsis thaliana. VL infection resulted in increased production of cell wall material with an altered composition of carbohydrate polymers and increased lignification. The abundance of several hundred soluble metabolites changed in the apoplast of VL-infected plants including signalling and defence compounds such as glycosides of salicylic acid, lignans and dihydroxybenzoic acid as well as oxylipins. The extracellular proteome of healthy leaves was enriched in antifungal proteins. VL caused specific increases in six apoplast proteins (three peroxidases PRX52, PRX34, P37, serine carboxypeptidase SCPL20, α-galactosidase AGAL2 and a germin-like protein GLP3), which have functions in defence and cell wall modification. The abundance of a lectin-like, chitin-inducible protein (CILLP) was reduced. Since the transcript levels of most of the induced proteins were not elevated until late infection time points (>20 dpi), whereas those of CILLP and GLP3 were reduced at earlier time points, our results may suggest that VL enhances its virulence by rapid down-regulation and delay of induction of plant defence genes. PMID:22363647

  17. Growth temperature impact on leaf form and function in Arabidopsis thaliana ecotypes from northern and southern Europe.

    PubMed

    Stewart, Jared J; Demmig-Adams, Barbara; Cohu, Christopher M; Wenzl, Coleman A; Muller, Onno; Adams, William W

    2016-07-01

    The plasticity of leaf form and function in European lines of Arabidopsis thaliana was evaluated in ecotypes from Sweden and Italy grown under contrasting (cool versus hot) temperature regimes. Although both ecotypes exhibited acclimatory adjustments, the Swedish ecotype exhibited more pronounced responses to the two contrasting temperature regimes in several characterized features. These responses included thicker leaves with higher capacities for photosynthesis, likely facilitated by a greater number of phloem cells per minor vein for the active loading and export of sugars, when grown under cool temperature as opposed to leaves with a higher vein density and a greater number of tracheary elements per minor vein, likely facilitating higher rates of transpirational water loss (and thus evaporative cooling), when grown under hot temperature with high water availability. In addition, only the Swedish ecotype exhibited reduced rosette growth and greater levels of foliar tocopherols under the hot growth temperature. These responses, and the greater responsiveness of the Swedish ecotype compared with the Italian ecotype, are discussed in the context of redox signalling networks and transcription factors, and the greater range of environmental conditions experienced by the Swedish versus the Italian ecotype during the growing season in their native habitats. PMID:26832121

  18. Isotopically nonstationary 13C flux analysis of changes in Arabidopsis thaliana leaf metabolism due to high light acclimation.

    PubMed

    Ma, Fangfang; Jazmin, Lara J; Young, Jamey D; Allen, Doug K

    2014-11-25

    Improving plant productivity is an important aim for metabolic engineering. There are few comprehensive methods that quantitatively describe leaf metabolism, although such information would be valuable for increasing photosynthetic capacity, enhancing biomass production, and rerouting carbon flux toward desirable end products. Isotopically nonstationary metabolic flux analysis (INST-MFA) has been previously applied to map carbon fluxes in photoautotrophic bacteria, which involves model-based regression of transient (13)C-labeling patterns of intracellular metabolites. However, experimental and computational difficulties have hindered its application to terrestrial plant systems. We performed in vivo isotopic labeling of Arabidopsis thaliana rosettes with (13)CO2 and estimated fluxes throughout leaf photosynthetic metabolism by INST-MFA. Plants grown at 200 µmol m(-2)s(-1) light were compared with plants acclimated for 9 d at an irradiance of 500 µmol⋅m(-2)⋅s(-1). Approximately 1,400 independent mass isotopomer measurements obtained from analysis of 37 metabolite fragment ions were regressed to estimate 136 total fluxes (54 free fluxes) under each condition. The results provide a comprehensive description of changes in carbon partitioning and overall photosynthetic flux after long-term developmental acclimation of leaves to high light. Despite a doubling in the carboxylation rate, the photorespiratory flux increased from 17 to 28% of net CO2 assimilation with high-light acclimation (Vc/Vo: 3.5:1 vs. 2.3:1, respectively). This study highlights the potential of (13)C INST-MFA to describe emergent flux phenotypes that respond to environmental conditions or plant physiology and cannot be obtained by other complementary approaches. PMID:25368168

  19. Genome-Wide Association Studies Identify Heavy Metal ATPase3 as the Primary Determinant of Natural Variation in Leaf Cadmium in Arabidopsis thaliana

    PubMed Central

    Chao, Dai-Yin; Silva, Adriano; Baxter, Ivan; Huang, Yu S.; Nordborg, Magnus; Danku, John; Lahner, Brett; Yakubova, Elena; Salt, David E.

    2012-01-01

    Understanding the mechanism of cadmium (Cd) accumulation in plants is important to help reduce its potential toxicity to both plants and humans through dietary and environmental exposure. Here, we report on a study to uncover the genetic basis underlying natural variation in Cd accumulation in a world-wide collection of 349 wild collected Arabidopsis thaliana accessions. We identified a 4-fold variation (0.5–2 µg Cd g−1 dry weight) in leaf Cd accumulation when these accessions were grown in a controlled common garden. By combining genome-wide association mapping, linkage mapping in an experimental F2 population, and transgenic complementation, we reveal that HMA3 is the sole major locus responsible for the variation in leaf Cd accumulation we observe in this diverse population of A. thaliana accessions. Analysis of the predicted amino acid sequence of HMA3 from 149 A. thaliana accessions reveals the existence of 10 major natural protein haplotypes. Association of these haplotypes with leaf Cd accumulation and genetics complementation experiments indicate that 5 of these haplotypes are active and 5 are inactive, and that elevated leaf Cd accumulation is associated with the reduced function of HMA3 caused by a nonsense mutation and polymorphisms that change two specific amino acids. PMID:22969436

  20. The LEA protein, ABR, is regulated by ABI5 and involved in dark-induced leaf senescence in Arabidopsis thaliana.

    PubMed

    Su, Mengying; Huang, Gan; Zhang, Qing; Wang, Xiao; Li, Chunxin; Tao, Yujin; Zhang, Shengchun; Lai, Jianbin; Yang, Chengwei; Wang, Yaqin

    2016-06-01

    The phytohormone abscisic acid (ABA) modulates plant growth and developmental processes such as leaf senescence. In this study, we investigated the role of the Arabidopsis late embryogenesis abundant (LEA) protein ABR (ABA-response protein) in delaying dark-induced leaf senescence. The ABR gene was up-regulated by treatment with ABA, NaCl and mannitol, as well as by light deprivation. In the dark, abr mutant plants displayed a premature leaf senescence phenotype, and various senescence-associated indicators, such as an increase in chlorophyll degradation and membrane leakiness, were enhanced, whereas 35S:ABR/abr transgenic lines showed a marked delay in dark-induced leaf senescence phenotypes. In vitro and in vivo assays showed that ABI5 bind to the ABR promoter, indicating that ABI5 directly regulates the expression of ABR. The disruption of ABI5 function in abr abi5-1 plants abolished the senescence-accelerating phenotype of the abr mutant, demonstrating that ABI5 is epistatic to ABR. In summary, these results highlight the important role that ABR, which is negatively regulated by ABI5, plays in delaying dark-induced leaf senescence. PMID:27095403

  1. Photosynthetic redox imbalance governs leaf sectoring in the Arabidopsis thaliana variegation mutants immutans, spotty, var1, and var2.

    PubMed

    Rosso, Dominic; Bode, Rainer; Li, Wenze; Krol, Marianna; Saccon, Diego; Wang, Shelly; Schillaci, Lori A; Rodermel, Steven R; Maxwell, Denis P; Hüner, Norman P A

    2009-11-01

    We hypothesized that chloroplast energy imbalance sensed through alterations in the redox state of the photosynthetic electron transport chain, measured as excitation pressure, governs the extent of variegation in the immutans mutant of Arabidopsis thaliana. To test this hypothesis, we developed a nondestructive imaging technique and used it to quantify the extent of variegation in vivo as a function of growth temperature and irradiance. The extent of variegation was positively correlated (R(2) = 0.750) with an increase in excitation pressure irrespective of whether high light, low temperature, or continuous illumination was used to induce increased excitation pressure. Similar trends were observed with the variegated mutants spotty, var1, and var2. Measurements of greening of etiolated wild-type and immutans cotyledons indicated that the absence of IMMUTANS increased excitation pressure twofold during the first 6 to 12 h of greening, which led to impaired biogenesis of thylakoid membranes. In contrast with IMMUTANS, the expression of its mitochondrial analog, AOX1a, was transiently upregulated in the wild type but permanently upregulated in immutans, indicating that the effects of excitation pressure during greening were also detectable in mitochondria. We conclude that mutations involving components of the photosynthetic electron transport chain, such as those present in immutans, spotty, var1, and var2, predispose Arabidopsis chloroplasts to photooxidation under high excitation pressure, resulting in the variegated phenotype. PMID:19897671

  2. Photosynthetic Redox Imbalance Governs Leaf Sectoring in the Arabidopsis thaliana Variegation Mutants immutans, spotty, var1, and var2[W

    PubMed Central

    Rosso, Dominic; Bode, Rainer; Li, Wenze; Krol, Marianna; Saccon, Diego; Wang, Shelly; Schillaci, Lori A.; Rodermel, Steven R.; Maxwell, Denis P.; Hüner, Norman P.A.

    2009-01-01

    We hypothesized that chloroplast energy imbalance sensed through alterations in the redox state of the photosynthetic electron transport chain, measured as excitation pressure, governs the extent of variegation in the immutans mutant of Arabidopsis thaliana. To test this hypothesis, we developed a nondestructive imaging technique and used it to quantify the extent of variegation in vivo as a function of growth temperature and irradiance. The extent of variegation was positively correlated (R2 = 0.750) with an increase in excitation pressure irrespective of whether high light, low temperature, or continuous illumination was used to induce increased excitation pressure. Similar trends were observed with the variegated mutants spotty, var1, and var2. Measurements of greening of etiolated wild-type and immutans cotyledons indicated that the absence of IMMUTANS increased excitation pressure twofold during the first 6 to 12 h of greening, which led to impaired biogenesis of thylakoid membranes. In contrast with IMMUTANS, the expression of its mitochondrial analog, AOX1a, was transiently upregulated in the wild type but permanently upregulated in immutans, indicating that the effects of excitation pressure during greening were also detectable in mitochondria. We conclude that mutations involving components of the photosynthetic electron transport chain, such as those present in immutans, spotty, var1, and var2, predispose Arabidopsis chloroplasts to photooxidation under high excitation pressure, resulting in the variegated phenotype. PMID:19897671

  3. Protection of Arabidopsis thaliana against Leaf-Pathogenic Pseudomonas syringae by Sphingomonas Strains in a Controlled Model System ▿ †

    PubMed Central

    Innerebner, Gerd; Knief, Claudia; Vorholt, Julia A.

    2011-01-01

    Diverse bacterial taxa live in association with plants without causing deleterious effects. Previous analyses of phyllosphere communities revealed the predominance of few bacterial genera on healthy dicotyl plants, provoking the question of whether these commensals play a particular role in plant protection. Here, we tested two of them, Methylobacterium and Sphingomonas, with respect to their ability to diminish disease symptom formation and the proliferation of the foliar plant pathogen Pseudomonas syringae pv. tomato DC3000 on Arabidopsis thaliana. Plants were grown under gnotobiotic conditions in the absence or presence of the potential antagonists and then challenged with the pathogen. No effect of Methylobacterium strains on disease development was observed. However, members of the genus Sphingomonas showed a striking plant-protective effect by suppressing disease symptoms and diminishing pathogen growth. A survey of different Sphingomonas strains revealed that most plant isolates protected A. thaliana plants from developing severe disease symptoms. This was not true for Sphingomonas strains isolated from air, dust, or water, even when they reached cell densities in the phyllosphere comparable to those of the plant isolates. This suggests that plant protection is common among plant-colonizing Sphingomonas spp. but is not a general trait conserved within the genus Sphingomonas. The carbon source profiling of representative isolates revealed differences between protecting and nonprotecting strains, suggesting that substrate competition plays a role in plant protection by Sphingomonas. However, other mechanisms cannot be excluded at this time. In conclusion, the ability to protect plants as shown here in a model system may be an unexplored, common trait of indigenous Sphingomonas spp. and may be of relevance under natural conditions. PMID:21421777

  4. Leaf apoplastic proteome composition in UV-B treated Arabidopsis thaliana mutants impaired in extracellular glutathione degradation

    PubMed Central

    Masi, A.; Trentin, A.R.; Arrigoni, G.

    2015-01-01

    In plants, environmental perturbations often result in oxidative reactions in the apoplastic space, which are counteracted for by enzymatic and non-enzymatic antioxidative systems, including ascorbate and glutathione. However, the occurrence of the latter and its exact role in the extracellular space are not well documented. In Arabidopsis thaliana, the gamma-glutamyl transferase isoform GGT1 bound to the cell wall takes part in the so-called gamma-glutamyl cycle for extracellular glutathione degradation and recovery, and may be implicated in redox sensing and balance. In this work, oxidative conditions were imposed with UV-B radiation and studied in redox altered ggt1 mutants. Elevated UV-B has detrimental effects on plant metabolism, plasma membranes representing a major target for ROS generated by this harmful radiation. The response of ggt1 knockout Arabidopsis leaves to UV-B radiation was assessed by investigating changes in apoplastic protein composition. We then compared the expression changes resulting from the mutation and from the UV-B treatment. Rearrangements occurring in apoplastic protein composition suggest the involvement of hydrogen peroxide, which may ultimately act as a signal. Other important changes related to hormonal effects, cell wall remodeling, and redox activities are also reported. We argue that oxidative stress conditions imposed by UV-B and by disruption of the gamma-glutamyl cycle result in similar stress-induced responses, to some degree at least. Data shown here are associated with the article from Trentin et al. (2015) [1]; protein data have been deposited to the PRIDE database (Vizcaíno et al., 2014) [2] with identifier PXD001807. PMID:26862584

  5. Pattern Dynamics in Adaxial-Abaxial Specific Gene Expression Are Modulated by a Plastid Retrograde Signal during Arabidopsis thaliana Leaf Development

    PubMed Central

    Tameshige, Toshiaki; Fujita, Hironori; Watanabe, Keiro; Toyokura, Koichi; Kondo, Maki; Tatematsu, Kiyoshi; Matsumoto, Noritaka; Tsugeki, Ryuji; Kawaguchi, Masayoshi; Nishimura, Mikio; Okada, Kiyotaka

    2013-01-01

    The maintenance and reformation of gene expression domains are the basis for the morphogenic processes of multicellular systems. In a leaf primordium of Arabidopsis thaliana, the expression of FILAMENTOUS FLOWER (FIL) and the activity of the microRNA miR165/166 are specific to the abaxial side. This miR165/166 activity restricts the target gene expression to the adaxial side. The adaxial and abaxial specific gene expressions are crucial for the wide expansion of leaf lamina. The FIL-expression and the miR165/166-free domains are almost mutually exclusive, and they have been considered to be maintained during leaf development. However, we found here that the position of the boundary between the two domains gradually shifts from the adaxial side to the abaxial side. The cell lineage analysis revealed that this boundary shifting was associated with a sequential gene expression switch from the FIL-expressing (miR165/166 active) to the miR165/166-free (non-FIL-expressing) states. Our genetic analyses using the enlarged fil expression domain2 (enf2) mutant and chemical treatment experiments revealed that impairment in the plastid (chloroplast) gene expression machinery retards this boundary shifting and inhibits the lamina expansion. Furthermore, these developmental effects caused by the abnormal plastids were not observed in the genomes uncoupled1 (gun1) mutant background. This study characterizes the dynamic nature of the adaxial-abaxial specification process in leaf primordia and reveals that the dynamic process is affected by the GUN1-dependent retrograde signal in response to the failure of plastid gene expression. These findings advance our understanding on the molecular mechanism linking the plastid function to the leaf morphogenic processes. PMID:23935517

  6. Re-evaluating the role of ascorbic acid and phenolic glycosides in ozone scavenging in the leaf apoplast of Arabidopsis thaliana L

    PubMed Central

    BOOKER, FITZGERALD L.; BURKEY, KENT O.; JONES, ALAN M.

    2016-01-01

    Phenolic glycosides are effective reactive oxygen scavengers and peroxidase substrates, suggesting that compounds in addition to ascorbate may have functional importance in defence responses against ozone (O3), especially in the leaf apoplast. The apoplastic concentrations of ascorbic acid (AA) and phenolic glycosides in Arabidopsis thaliana L. Col-0 wild-type plants were determined following exposure to a range of O3 concentrations (5, 125 or 175 nL L−1) in controlled environment chambers. AA in leaf apoplast extracts was almost entirely oxidized in all treatments, suggesting that O3 scavenging by direct reactions with reduced AA was very limited. In regard to phenolics, O3 stimulated transcription of numerous phenylpropanoid pathway genes and increased the apoplastic concentration of sinapoyl malate. However, modelling of O3 scavenging in the apoplast indicated that sinapoyl malate concentrations were too low to be effective protectants. Furthermore, null mutants for sinapoyl esters (fah1-7), kaempferol glycosides (tt4-1) and the double mutant (tt4-1/fah1-7) were equally sensitive to chronic O3 as Ler-0 wild-type plants. These results indicate that current understanding of O3 defence schemes deserves reassessment as mechanisms other than direct scavenging of O3 by extracellular AA and antioxidant activity of some phenolics may predominate in some plant species. PMID:22380512

  7. The intrinsically disordered protein LEA7 from Arabidopsis thaliana protects the isolated enzyme lactate dehydrogenase and enzymes in a soluble leaf proteome during freezing and drying.

    PubMed

    Popova, Antoaneta V; Rausch, Saskia; Hundertmark, Michaela; Gibon, Yves; Hincha, Dirk K

    2015-10-01

    The accumulation of Late Embryogenesis Abundant (LEA) proteins in plants is associated with tolerance against stresses such as freezing and desiccation. Two main functions have been attributed to LEA proteins: membrane stabilization and enzyme protection. We have hypothesized previously that LEA7 from Arabidopsis thaliana may stabilize membranes because it interacts with liposomes in the dry state. Here we show that LEA7, contrary to this expectation, did not stabilize liposomes during drying and rehydration. Instead, it partially preserved the activity of the enzyme lactate dehydrogenase (LDH) during drying and freezing. Fourier-transform infrared (FTIR) spectroscopy showed no evidence of aggregation of LDH in the dry or rehydrated state under conditions that lead to complete loss of activity. To approximate the complex influence of intracellular conditions on the protective effects of a LEA protein in a convenient in-vitro assay, we measured the activity of two Arabidopsis enzymes (glucose-6-P dehydrogenase and ADP-glucose pyrophosphorylase) in total soluble leaf protein extract (Arabidopsis soluble proteome, ASP) after drying and rehydration or freezing and thawing. LEA7 partially preserved the activity of both enzymes under these conditions, suggesting its role as an enzyme protectant in vivo. Further FTIR analyses indicated the partial reversibility of protein aggregation in the dry ASP during rehydration. Similarly, aggregation in the dry ASP was strongly reduced by LEA7. In addition, mixtures of LEA7 with sucrose or verbascose reduced aggregation more than the single additives, presumably through the effects of the protein on the H-bonding network of the sugar glasses. PMID:25988244

  8. Mutations in circularly permuted GTPase family genes AtNOA1/RIF1/SVR10 and BPG2 suppress var2-mediated leaf variegation in Arabidopsis thaliana.

    PubMed

    Qi, Yafei; Zhao, Jun; An, Rui; Zhang, Juan; Liang, Shuang; Shao, Jingxia; Liu, Xiayan; An, Lijun; Yu, Fei

    2016-03-01

    Leaf variegation mutants constitute a unique group of chloroplast development mutants and are ideal genetic materials to dissect the regulation of chloroplast development. We have utilized the Arabidopsis yellow variegated (var2) mutant and genetic suppressor analysis to probe the mechanisms of chloroplast development. Here we report the isolation of a new var2 suppressor locus SUPPRESSOR OF VARIEGATION (SVR10). Genetic mapping and molecular complementation indicated that SVR10 encodes a circularly permuted GTPase that has been reported as Arabidopsis thaliana NITRIC OXIDE ASSOCIATED 1 (AtNOA1) and RESISTANT TO INHIBITION BY FOSMIDOMYCIN 1 (RIF1). Biochemical evidence showed that SVR10/AtNOA1/RIF1 likely localizes to the chloroplast stroma. We further demonstrate that the mutant of a close homologue of SVR10/AtNOA1/RIF1, BRASSINAZOLE INSENSITIVE PALE GREEN 2 (BPG2), can also suppress var2 leaf variegation. Mutants of SVR10 and BPG2 are impaired in photosynthesis and the accumulation of chloroplast proteins. Interestingly, two-dimensional blue native gel analysis showed that mutants of SVR10 and BPG2 display defects in the assembly of thylakoid membrane complexes including reduced levels of major photosynthetic complexes and the abnormal accumulation of a chlorophyll-protein supercomplex containing photosystem I. Taken together, our findings suggest that SVR10 and BPG2 are functionally related with VAR2, likely through their potential roles in regulating chloroplast protein homeostasis, and both SVR10 and BPG2 are required for efficient thylakoid protein complex assembly and photosynthesis. PMID:26435530

  9. Decreased glycolate oxidase activity leads to altered carbon allocation and leaf senescence after a transfer from high CO2 to ambient air in Arabidopsis thaliana.

    PubMed

    Dellero, Younès; Jossier, Mathieu; Glab, Nathalie; Oury, Céline; Tcherkez, Guillaume; Hodges, Michael

    2016-05-01

    Metabolic and physiological analyses of Arabidopsis thaliana glycolate oxidase (GOX) mutant leaves were performed to understand the development of the photorespiratory phenotype after transfer from high CO2 to air. We show that two Arabidopsis genes, GOX1 and GOX2, share a redundant photorespiratory role. Air-grown single gox1 and gox2 mutants grew normally and no significant differences in leaf metabolic levels and photosynthetic activities were found when compared with wild-type plants. To study the impact of a highly reduced GOX activity on plant metabolism, both GOX1 and GOX2 expression was knocked-down using an artificial miRNA strategy. Air-grown amiRgox1/2 plants with a residual 5% GOX activity exhibited a severe growth phenotype. When high-CO2-grown adult plants were transferred to air, the photosynthetic activity of amiRgox1/2 was rapidly reduced to 50% of control levels, and a high non-photochemical chlorophyll fluorescence quenching was maintained. (13)C-labeling revealed that daily assimilated carbon accumulated in glycolate, leading to reduced carbon allocation to sugars, organic acids, and amino acids. Such changes were not always mirrored in leaf total metabolite levels, since many soluble amino acids increased after transfer, while total soluble protein, RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase), and chlorophyll amounts decreased in amiRgox1/2 plants. The senescence marker, SAG12, was induced only in amiRgox1/2 rosettes after transfer to air. The expression of maize photorespiratory GOX in amiRgox1/2 abolished all observed phenotypes. The results indicate that the inhibition of the photorespiratory cycle negatively impacts photosynthesis, alters carbon allocation, and leads to early senescence in old rosette leaves. PMID:26896850

  10. Detection of oligonucleotide hybridization at femtomolar level and sequence-specific gene analysis of the Arabidopsis thaliana leaf extract with an ultrasensitive surface plasmon resonance spectrometer

    PubMed Central

    Song, Fayi; Zhou, Feimeng; Wang, Jun; Tao, Nongjian; Lin, Jianqiao; Vellanoweth, Robert L.; Morquecho, Yvonne; Wheeler-Laidman, Janel

    2002-01-01

    A flow-injection (FI) device is combined, through the use of a low-volume (4 µl) flow cell, with an ultrasensitive surface plasmon resonance (SPR) spectrometer equipped with a bi-cell photodiode detector. The application of this novel FI–SPR device for sequence-specific ultratrace analysis of oligodeoxynucleotides (ODNs) and polydeoxynucleotides was demonstrated. Self-assembled monolayers of ODN probes are tethered onto Au films with a mercaptohexyl group at the 3′ ends. The FI–SPR provides a detection level (≤54 fM) 2–3 orders of magnitude lower than other SPR devices and compares well with several ultrasensitive detection methods for labeled DNA targets (e.g. fluorophore-tagged and radiolabeled DNA samples). The technique is also highly selective, since a 47mer ODN target with a single-base mismatch yielded a much smaller SPR signal, and a specific interaction was detected when the complementary target was present at 0.001% of the total DNA. The FI–SPR was extended to the measurement of two individual genes in a cDNA mixture transcribed from an Arabidopsis thaliana leaf mRNA pool. The greatly enhanced sensitivity not only obviates the necessity of DNA labeling, but also significantly reduces sample consumption, allowing direct quantification of low abundance mRNAs in cellular samples without amplification. PMID:12136120

  11. Sulfenome mining in Arabidopsis thaliana.

    PubMed

    Waszczak, Cezary; Akter, Salma; Eeckhout, Dominique; Persiau, Geert; Wahni, Khadija; Bodra, Nandita; Van Molle, Inge; De Smet, Barbara; Vertommen, Didier; Gevaert, Kris; De Jaeger, Geert; Van Montagu, Marc; Messens, Joris; Van Breusegem, Frank

    2014-08-01

    Reactive oxygen species (ROS) have been shown to be potent signaling molecules. Today, oxidation of cysteine residues is a well-recognized posttranslational protein modification, but the signaling processes steered by such oxidations are poorly understood. To gain insight into the cysteine thiol-dependent ROS signaling in Arabidopsis thaliana, we identified the hydrogen peroxide (H2O2)-dependent sulfenome: that is, proteins with at least one cysteine thiol oxidized to a sulfenic acid. By means of a genetic construct consisting of a fusion between the C-terminal domain of the yeast (Saccharomyces cerevisiae) AP-1-like (YAP1) transcription factor and a tandem affinity purification tag, we detected ∼ 100 sulfenylated proteins in Arabidopsis cell suspensions exposed to H2O2 stress. The in vivo YAP1-based trapping of sulfenylated proteins was validated by a targeted in vitro analysis of dehydroascorbate reductase2 (DHAR2). In DHAR2, the active site nucleophilic cysteine is regulated through a sulfenic acid-dependent switch, leading to S-glutathionylation, a protein modification that protects the protein against oxidative damage. PMID:25049418

  12. Protein expression in Arabidopsis thaliana after chronic clinorotation

    NASA Technical Reports Server (NTRS)

    Piastuch, William C.; Brown, Christopher S.

    1994-01-01

    Soluble protein expression in Arabidopsis thaliana L. (Heynh.) leaf and stem tissue was examined after chronic clinorotation. Seeds of Arabidopsis were germinated and plants grown to maturity on horizontal or vertical slow-rotating clinostats (1 rpm) or in stationary vertical control units. Total soluble proteins and in vivo-labeled soluble proteins isolated from these plants were analyzed by two-dimensional sodium doedocyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) and subsequent fluorography. Visual and computer analysis of the resulting protein patterns showed no significant differences in either total protein expression or in active protein synthesis between horizontal clinorotation and vertical controls in the Arabidopsis leaf and stem tissue. These results show chronic clinorotation does not cause gross changes in protein expression in Arabidopsis.

  13. Protein expression in Arabidopsis thaliana after chronic clinorotation

    NASA Technical Reports Server (NTRS)

    Piastuch, W. C.; Brown, C. S.

    1995-01-01

    Soluble protein expression in Arabidopsis thaliana L. (Heynh.) leaf and stem tissue was examined after chronic clinorotation. Seeds of Arabidopsis were germinated and plants grown to maturity on horizontal or vertical slow-rotating clinostats (1 rpm) or in stationary vertical control units. Total soluble proteins and in vivo-labeled soluble proteins isolated from these plants were analyzed by two-dimensional SDS PAGE and subsequent fluorography. Visual and computer analysis of the resulting protein patterns showed no significant differences in either total protein expression or in active protein synthesis between horizontal clinorotation and vertical controls in the Arabidopsis leaf and stem tissue. These results show chronic clinorotation does not cause gross changes in protein expression in Arabidopsis.

  14. Abscisic Acid as an Internal Integrator of Multiple Physiological Processes Modulates Leaf Senescence Onset in Arabidopsis thaliana

    PubMed Central

    Song, Yuwei; Xiang, Fuyou; Zhang, Guozeng; Miao, Yuchen; Miao, Chen; Song, Chun-Peng

    2016-01-01

    Many studies have shown that exogenous abscisic acid (ABA) promotes leaf abscission and senescence. However, owing to a lack of genetic evidence, ABA function in plant senescence has not been clearly defined. Here, two-leaf early-senescence mutants (eas) that were screened by chlorophyll fluorescence imaging and named eas1-1 and eas1-2 showed high photosynthetic capacity in the early stage of plant growth compared with the wild type. Gene mapping showed that eas1-1 and eas1-2 are two novel ABA2 allelic mutants. Under unstressed conditions, the eas1 mutations caused plant dwarf, early germination, larger stomatal apertures, and early leaf senescence compared with those of the wild type. Flow cytometry assays showed that the cell apoptosis rate in eas1 mutant leaves was higher than that of the wild type after day 30. A significant increase in the transcript levels of several senescence-associated genes, especially SAG12, was observed in eas1 mutant plants in the early stage of plant growth. More importantly, ABA-activated calcium channel activity in plasma membrane and induced the increase of cytoplasmic calcium concentration in guard cells are suppressed due to the mutation of EAS1. In contrast, the eas1 mutants lost chlorophyll and ion leakage significant faster than in the wild type under treatment with calcium channel blocker. Hence, our results indicate that endogenous ABA level is an important factor controlling the onset of leaf senescence through Ca2+ signaling. PMID:26925086

  15. Abscisic Acid as an Internal Integrator of Multiple Physiological Processes Modulates Leaf Senescence Onset in Arabidopsis thaliana.

    PubMed

    Song, Yuwei; Xiang, Fuyou; Zhang, Guozeng; Miao, Yuchen; Miao, Chen; Song, Chun-Peng

    2016-01-01

    Many studies have shown that exogenous abscisic acid (ABA) promotes leaf abscission and senescence. However, owing to a lack of genetic evidence, ABA function in plant senescence has not been clearly defined. Here, two-leaf early-senescence mutants (eas) that were screened by chlorophyll fluorescence imaging and named eas1-1 and eas1-2 showed high photosynthetic capacity in the early stage of plant growth compared with the wild type. Gene mapping showed that eas1-1 and eas1-2 are two novel ABA2 allelic mutants. Under unstressed conditions, the eas1 mutations caused plant dwarf, early germination, larger stomatal apertures, and early leaf senescence compared with those of the wild type. Flow cytometry assays showed that the cell apoptosis rate in eas1 mutant leaves was higher than that of the wild type after day 30. A significant increase in the transcript levels of several senescence-associated genes, especially SAG12, was observed in eas1 mutant plants in the early stage of plant growth. More importantly, ABA-activated calcium channel activity in plasma membrane and induced the increase of cytoplasmic calcium concentration in guard cells are suppressed due to the mutation of EAS1. In contrast, the eas1 mutants lost chlorophyll and ion leakage significant faster than in the wild type under treatment with calcium channel blocker. Hence, our results indicate that endogenous ABA level is an important factor controlling the onset of leaf senescence through Ca(2+) signaling. PMID:26925086

  16. Agrobacterium tumefaciens-mediated transient transformation of Arabidopsis thaliana leaves.

    PubMed

    Mangano, Silvina; Gonzalez, Cintia Daniela; Petruccelli, Silvana

    2014-01-01

    Transient assays provide a convenient alternative to stable transformation. Compared to the generation of stably transformed plants, agroinfiltration is more rapid, and samples can be analyzed a few days after inoculation. Nevertheless, at difference of tobacco and other plant species, Arabidopsis thaliana remains recalcitrant to routine transient assays. In this chapter, we describe a transient expression assay using simple infiltration of intact Arabidopsis leaves with Agrobacterium tumefaciens carrying a plasmid expressing a reporter fluorescent protein. In this protocol, Agrobacterium aggressiveness was increased by a prolonged treatment in an induction medium deficient in nutrients and containing acetosyringone. Besides, Arabidopsis plants were cultivated in intermediate photoperiod (12 h light-12 h dark) to promote leaf growth. PMID:24057365

  17. Flavonoid-specific staining of Arabidopsis thaliana.

    PubMed

    Sheahan, J J; Rechnitz, G A

    1992-12-01

    Crop yields may be threatened by increases in UV-B radiation resulting from depletion of the ozone layer. In higher plants, the presence of flavonols provides a protective mechanism, and we report a novel staining procedure for the visualization of such protectants in plant tissue. It is shown that the proposed technique provides sensitive and specific fluorescence of flavonoids in chlorophyll-bleached tissue of Arabidopsis thaliana. PMID:1282347

  18. Bioavailability of nanoparticulate hematite to Arabidopsis thaliana.

    PubMed

    Marusenko, Yevgeniy; Shipp, Jessie; Hamilton, George A; Morgan, Jennifer L L; Keebaugh, Michael; Hill, Hansina; Dutta, Arnab; Zhuo, Xiaoding; Upadhyay, Nabin; Hutchings, James; Herckes, Pierre; Anbar, Ariel D; Shock, Everett; Hartnett, Hilairy E

    2013-03-01

    The environmental effects and bioavailability of nanoparticulate iron (Fe) to plants are currently unknown. Here, plant bioavailability of synthesized hematite Fe nanoparticles was evaluated using Arabidopsis thaliana (A. thaliana) as a model. Over 56-days of growing wild-type A. thaliana, the nanoparticle-Fe and no-Fe treatments had lower plant biomass, lower chlorophyll concentrations, and lower internal Fe concentrations than the Fe-treatment. Results for the no-Fe and nanoparticle-Fe treatments were consistently similar throughout the experiment. These results suggest that nanoparticles (mean diameter 40.9 nm, range 22.3-67.0 nm) were not taken up and therefore not bioavailable to A. thaliana. Over 14-days growing wild-type and transgenic (Type I/II proton pump overexpression) A. thaliana, the Type I plant grew more than the wild-type in the nanoparticle-Fe treatment, suggesting Type I plants cope better with Fe limitation; however, the nanoparticle-Fe and no-Fe treatments had similar growth for all plant types. PMID:23262070

  19. Genetic Regulation of Transcriptional Variation in Natural Arabidopsis thaliana Accessions

    PubMed Central

    Zan, Yanjun; Shen, Xia; Forsberg, Simon K. G.; Carlborg, Örjan

    2016-01-01

    An increased knowledge of the genetic regulation of expression in Arabidopsis thaliana is likely to provide important insights about the basis of the plant’s extensive phenotypic variation. Here, we reanalyzed two publicly available datasets with genome-wide data on genetic and transcript variation in large collections of natural A. thaliana accessions. Transcripts from more than half of all genes were detected in the leaves of all accessions, and from nearly all annotated genes in at least one accession. Thousands of genes had high transcript levels in some accessions, but no transcripts at all in others, and this pattern was correlated with the genome-wide genotype. In total, 2669 eQTL were mapped in the largest population, and 717 of them were replicated in the other population. A total of 646 cis-eQTL-regulated genes that lacked detectable transcripts in some accessions was found, and for 159 of these we identified one, or several, common structural variants in the populations that were shown to be likely contributors to the lack of detectable RNA transcripts for these genes. This study thus provides new insights into the overall genetic regulation of global gene expression diversity in the leaf of natural A. thaliana accessions. Further, it also shows that strong cis-acting polymorphisms, many of which are likely to be structural variations, make important contributions to the transcriptional variation in the worldwide A. thaliana population. PMID:27226169

  20. Terpene Specialized Metabolism in Arabidopsis thaliana

    PubMed Central

    Tholl, Dorothea; Lee, Sungbeom

    2011-01-01

    Terpenes constitute the largest class of plant secondary (or specialized) metabolites, which are compounds of ecological function in plant defense or the attraction of beneficial organisms. Using biochemical and genetic approaches, nearly all Arabidopsis thaliana (Arabidopsis) enzymes of the core biosynthetic pathways producing the 5-carbon building blocks of terpenes have been characterized and closer insight has been gained into the transcriptional and posttranscriptional/translational mechanisms regulating these pathways. The biochemical function of most prenyltransferases, the downstream enzymes that condense the C5-precursors into central 10-, 15-, and 20-carbon prenyldiphosphate intermediates, has been described, although the function of several isoforms of C20-prenyltranferases is not well understood. Prenyl diphosphates are converted to a variety of C10-, C15-, and C20-terpene products by enzymes of the terpene synthase (TPS) family. Genomic organization of the 32 Arabidopsis TPS genes indicates a species-specific divergence of terpene synthases with tissue- and cell-type specific expression profiles that may have emerged under selection pressures by different organisms. Pseudogenization, differential expression, and subcellular segregation of TPS genes and enzymes contribute to the natural variation of terpene biosynthesis among Arabidopsis accessions (ecotypes) and species. Arabidopsis will remain an important model to investigate the metabolic organization and molecular regulatory networks of terpene specialized metabolism in relation to the biological activities of terpenes. PMID:22303268

  1. Tetrapyrrole Metabolism in Arabidopsis thaliana

    PubMed Central

    Tanaka, Ryouichi; Kobayashi, Koichi; Masuda, Tatsuru

    2011-01-01

    Higher plants produce four classes of tetrapyrroles, namely, chlorophyll (Chl), heme, siroheme, and phytochromobilin. In plants, tetrapyrroles play essential roles in a wide range of biological activities including photosynthesis, respiration and the assimilation of nitrogen/sulfur. All four classes of tetrapyrroles are derived from a common biosynthetic pathway that resides in the plastid. In this article, we present an overview of tetrapyrrole metabolism in Arabidopsis and other higher plants, and we describe all identified enzymatic steps involved in this metabolism. We also summarize recent findings on Chl biosynthesis and Chl breakdown. Recent advances in this field, in particular those on the genetic and biochemical analyses of novel enzymes, prompted us to redraw the tetrapyrrole metabolic pathways. In addition, we also summarize our current understanding on the regulatory mechanisms governing tetrapyrrole metabolism. The interactions of tetrapyrrole biosynthesis and other cellular processes including the plastid-to-nucleus signal transduction are discussed. PMID:22303270

  2. Metabolic fingerprinting of Arabidopsis thaliana accessions.

    PubMed

    Sotelo-Silveira, Mariana; Chauvin, Anne-Laure; Marsch-Martínez, Nayelli; Winkler, Robert; de Folter, Stefan

    2015-01-01

    In the post-genomic era much effort has been put on the discovery of gene function using functional genomics. Despite the advances achieved by these technologies in the understanding of gene function at the genomic and proteomic level, there is still a big genotype-phenotype gap. Metabolic profiling has been used to analyze organisms that have already been characterized genetically. However, there is a small number of studies comparing the metabolic profile of different tissues of distinct accessions. Here, we report the detection of over 14,000 and 17,000 features in inflorescences and leaves, respectively, in two widely used Arabidopsis thaliana accessions. A predictive Random Forest Model was developed, which was able to reliably classify tissue type and accession of samples based on LC-MS profile. Thereby we demonstrate that the morphological differences among A. thaliana accessions are reflected also as distinct metabolic phenotypes within leaves and inflorescences. PMID:26074932

  3. Metabolic fingerprinting of Arabidopsis thaliana accessions

    PubMed Central

    Sotelo-Silveira, Mariana; Chauvin, Anne-Laure; Marsch-Martínez, Nayelli; Winkler, Robert; de Folter, Stefan

    2015-01-01

    In the post-genomic era much effort has been put on the discovery of gene function using functional genomics. Despite the advances achieved by these technologies in the understanding of gene function at the genomic and proteomic level, there is still a big genotype-phenotype gap. Metabolic profiling has been used to analyze organisms that have already been characterized genetically. However, there is a small number of studies comparing the metabolic profile of different tissues of distinct accessions. Here, we report the detection of over 14,000 and 17,000 features in inflorescences and leaves, respectively, in two widely used Arabidopsis thaliana accessions. A predictive Random Forest Model was developed, which was able to reliably classify tissue type and accession of samples based on LC-MS profile. Thereby we demonstrate that the morphological differences among A. thaliana accessions are reflected also as distinct metabolic phenotypes within leaves and inflorescences. PMID:26074932

  4. Arabidopsis thaliana glucuronosyltransferase in family GT14.

    PubMed

    Dilokpimol, Adiphol; Geshi, Naomi

    2014-01-01

    Arabinogalactan proteins are abundant cell-surface proteoglycans in plants and are involved in many cellular processes including somatic embryogenesis, cell-cell interactions, and cell elongation. We reported a glucuronosyltransferase encoded by Arabidopsis AtGlcAT14A, which catalyzes an addition of glucuronic acid residues to β-1,3- and β-1,6-linked galactans of arabinogalactan (Knoch et al. 2013). The knockout mutant of this gene resulted in the enhanced growth rate of hypocotyls and roots of seedlings, suggesting an involvement of AtGlcAT14A in cell elongation. AtGlcAt14A belongs to the family GT14 in the Carbohydrate Active Enzyme database (CAZy; www.cazy.org), in which a total of 11 proteins, including AtGLCAT14A, are classified from Arabidopsis thaliana. In this paper, we report the enzyme activities for the rest of the Arabidopsis GT14 isoforms, analyzed in the same way as for AtGlcAT14A. Evidently, two other Arabidopsis GT14 isoforms, At5g15050 and At2g37585, also possess the glucuronosyltransferase activity adding glucuronic acid residues to β-1,3- and β-1,6-linked galactans. Therefore, we named At5g15050 and At2g37585 as AtGlcAT14B and AtGlcAT14C, respectively. PMID:24739253

  5. Metabolic footprint of epiphytic bacteria on Arabidopsis thaliana leaves.

    PubMed

    Ryffel, Florian; Helfrich, Eric J N; Kiefer, Patrick; Peyriga, Lindsay; Portais, Jean-Charles; Piel, Jörn; Vorholt, Julia A

    2016-03-01

    The phyllosphere, which is defined as the parts of terrestrial plants above the ground, is a large habitat for different microorganisms that show a high extent of adaption to their environment. A number of hypotheses were generated by culture-independent functional genomics studies to explain the competitiveness of specialized bacteria in the phyllosphere. In contrast, in situ data at the metabolome level as a function of bacterial colonization are lacking. Here, we aimed to obtain new insights into the metabolic interplay between host and epiphytes upon colonization of Arabidopsis thaliana leaves in a controlled laboratory setting using environmental metabolomics approaches. Quantitative nuclear magnetic resonance (NMR) and imaging high-resolution mass spectrometry (IMS) methods were used to identify Arabidopsis leaf surface compounds and their possible involvement in the epiphytic lifestyle by relative changes in compound pools. The dominant carbohydrates on the leaf surfaces were sucrose, fructose and glucose. These sugars were significantly and specifically altered after epiphytic leaf colonization by the organoheterotroph Sphingomonas melonis or the phytopathogen Pseudomonas syringae pv. tomato, but only to a minor extent by the methylotroph Methylobacterium extorquens. In addition to carbohydrates, IMS revealed surprising alterations in arginine metabolism and phytoalexin biosynthesis that were dependent on the presence of bacteria, which might reflect the consequences of bacterial activity and the recognition of not only pathogens but also commensals by the plant. These results highlight the power of environmental metabolomics to aid in elucidating the molecular basis underlying plant-epiphyte interactions in situ. PMID:26305156

  6. Defects in leaf carbohydrate metabolism compromise acclimation to high light and lead to a high chlorophyll fluorescence phenotype in Arabidopsis thaliana

    PubMed Central

    2012-01-01

    Background We have studied the impact of carbohydrate-starvation on the acclimation response to high light using Arabidopsis thaliana double mutants strongly impaired in the day- and night path of photoassimilate export from the chloroplast. A complete knock-out mutant of the triose phosphate/phosphate translocator (TPT; tpt-2 mutant) was crossed to mutants defective in (i) starch biosynthesis (adg1-1, pgm1 and pgi1-1; knock-outs of ADP-glucose pyrophosphorylase, plastidial phosphoglucomutase and phosphoglucose isomerase) or (ii) starch mobilization (sex1-3, knock-out of glucan water dikinase) as well as in (iii) maltose export from the chloroplast (mex1-2). Results All double mutants were viable and indistinguishable from the wild type when grown under low light conditions, but - except for sex1-3/tpt-2 - developed a high chlorophyll fluorescence (HCF) phenotype and growth retardation when grown in high light. Immunoblots of thylakoid proteins, Blue-Native gel electrophoresis and chlorophyll fluorescence emission analyses at 77 Kelvin with the adg1-1/tpt-2 double mutant revealed that HCF was linked to a specific decrease in plastome-encoded core proteins of both photosystems (with the exception of the PSII component cytochrome b559), whereas nuclear-encoded antennae (LHCs) accumulated normally, but were predominantly not attached to their photosystems. Uncoupled antennae are the major cause for HCF of dark-adapted plants. Feeding of sucrose or glucose to high light-grown adg1-1/tpt-2 plants rescued the HCF- and growth phenotypes. Elevated sugar levels induce the expression of the glucose-6-phosphate/phosphate translocator2 (GPT2), which in principle could compensate for the deficiency in the TPT. A triple mutant with an additional defect in GPT2 (adg1-1/tpt-2/gpt2-1) exhibited an identical rescue of the HCF- and growth phenotype in response to sugar feeding as the adg1-1/tpt-2 double mutant, indicating that this rescue is independent from the sugar

  7. Piriformospora indica Stimulates Root Metabolism of Arabidopsis thaliana.

    PubMed

    Strehmel, Nadine; Mönchgesang, Susann; Herklotz, Siska; Krüger, Sylvia; Ziegler, Jörg; Scheel, Dierk

    2016-01-01

    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. PMID:27399695

  8. A comparison of metabolite extraction strategies for 1H-NMR-based metabolic profiling using mature leaf tissue from the model plant Arabidopsis thaliana.

    PubMed

    Kaiser, Kayla A; Barding, Gregory A; Larive, Cynthia K

    2009-12-01

    Metabolite analysis is recognized as an important facet of systems biology, however complete metabolome characterization has not been realized due to challenges in sample preparation, inherent instrumental limitations and the labor intensive task of data interpretation. This work aims to compare several commonly used metabolite extraction strategies for their effect on the (1)H nuclear magnetic resonance (NMR) metabolic profile of extracts of the model plant Arabidopsis thaliana. Extractions were carried out on aliquots from a pool of homogenized plant tissue using CD(3)CN/D(2)O, buffered D(2)O, perchloric acid in D(2)O, CD(3)OD/D(2)O and CD(3)OD/D(2)O/CDCl(3) as the extraction solvents. The effects of lyophilization as a sample pretreatment, solvent evaporation and extract fractionation for removal of interfering species were studied. Representative spectra are presented for qualitative interpretation. Analytical reproducibility was evaluated by principal components analysis. Perchloric acid facilitated acid-catalyzed cleavage of sucrose, further complicating biological interpretation of the resulting metabolite profile. The solvent system CD(3)OD/D(2)O/CDCl(3) gave the least reproducible results in our hands. D(2)O extracts suffered from poor stability probably due to contamination by soluble enzymes, which were not denatured in this solvent. CD(3)CN/D(2)O extracts showed greater stability than D(2)O alone, but problems were encountered due to degradation of (1)H NMR spectral resolution during lengthy acquisitions due to partial phase separation. In addition, this solvent system produced spectra with significant contamination by lipids that obscured spectral regions containing the resonances of the aliphatic amino acids. These problems were solved by speedvacuuming the CD(3)CN/D(2)O extract and reconstituting in D(2)O solution. PMID:19551810

  9. Crystal structure of Arabidopsis thaliana cytokinin dehydrogenase

    SciTech Connect

    Bae, Euiyoung; Bingman, Craig A.; Bitto, Eduard; Aceti, David J.; Phillips, Jr., George N.

    2008-08-13

    Since first discovered in Zea mays, cytokinin dehydrogenase (CKX) genes have been identified in many plants including rice and Arabidopsis thaliana, which possesses CKX homologues (AtCKX1-AtCKX7). So far, the three-dimensional structure of only Z. mays CKX (ZmCKX1) has been determined. The crystal structures of ZmCKX1 have been solved in the native state and in complex with reaction products and a slowly reacting substrate. The structures revealed four glycosylated asparagine residues and a histidine residue covalently linked to FAD. Combined with the structural information, recent biochemical analyses of ZmCKX1 concluded that the final products of the reaction, adenine and a side chain aldehyde, are formed by nonenzymatic hydrolytic cleavage of cytokinin imine products resulting directly from CKX catalysis. Here, we report the crystal structure of AtCKX7 (gene locus At5g21482.1, UniProt code Q9FUJ1).

  10. Photoperiodic flowering regulation in Arabidopsis thaliana

    PubMed Central

    Golembeski, Greg S.; Kinmonth-Schultz, Hannah A.; Song, Young Hun; Imaizumi, Takato

    2015-01-01

    Photoperiod, or the duration of light in a given day, is a critical cue that flowering plants utilize to effectively assess seasonal information and coordinate their reproductive development in synchrony with the external environment. The use of the model plant, Arabidopsis thaliana, has greatly improved our understanding of the molecular mechanisms that determine how plants process and utilize photoperiodic information to coordinate a flowering response. This mechanism is typified by the transcriptional activation of FLOWERING LOCUS T (FT) gene by the transcription factor CONSTANS (CO) under inductive long-day conditions in Arabidopsis. FT protein then moves from the leaves to the shoot apex, where floral meristem development can be initiated. As a point of integration from a variety of environmental factors in the context of a larger system of regulatory pathways that affect flowering, the importance of photoreceptors and the circadian clock in CO regulation throughout the day has been a key feature of the photoperiodic flowering pathway. In addition to these established mechanisms, the recent discovery of a photosynthate derivative trehalose-6-phosphate as an activator of FT in leaves has interesting implications for the involvement of photosynthesis in the photoperiodic flowering response that were suggested from previous physiological experiments in flowering induction. PMID:25684830

  11. Piriformospora indica Stimulates Root Metabolism of Arabidopsis thaliana

    PubMed Central

    Strehmel, Nadine; Mönchgesang, Susann; Herklotz, Siska; Krüger, Sylvia; Ziegler, Jörg; Scheel, Dierk

    2016-01-01

    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 PMID:27399695

  12. Arabidopsis thaliana contains a single gene encoding squalene synthase.

    PubMed

    Busquets, Antoni; Keim, Verónica; Closa, Marta; del Arco, Ana; Boronat, Albert; Arró, Montserrat; Ferrer, Albert

    2008-05-01

    Squalene synthase (SQS) catalyzes the condensation of two molecules of farnesyl diphosphate (FPP) to produce squalene (SQ), the first committed precursor for sterol, brassinosteroid, and triterpene biosynthesis. Arabidopsis thaliana contains two SQS-annotated genomic sequences, At4g34640 (SQS1) and At4g34650 (SQS2), organized in a tandem array. Here we report that the SQS1 gene is widely expressed in all tissues throughout plant development, whereas SQS2 is primarily expressed in the vascular tissue of leaf and cotyledon petioles, and the hypocotyl of seedlings. Neither the complete A. thaliana SQS2 protein nor the chimeric SQS resulting from the replacement of the 69 C-terminal residues of SQS2 by the 111 C-terminal residues of the Schizosaccharomyces pombe SQS were able to confer ergosterol prototrophy to a Saccharomyces cerevisiae erg9 mutant strain lacking SQS activity. A soluble form of SQS2 expressed in Escherichia coli and purified was unable to synthesize SQ from FPP in the presence of NADPH and either Mg2+ or Mn2+. These results demonstrated that SQS2 has no SQS activity, so that SQS1 is the only functional SQS in A. thaliana. Mutational studies revealed that the lack of SQS activity of SQS2 cannot be exclusively attributed to the presence of an unusual Ser replacing the highly conserved Phe at position 287. Expression of green fluorescent protein (GFP)-tagged versions of SQS1 in onion epidermal cells demonstrated that SQS1 is targeted to the endoplasmic reticulum (ER) membrane and that this location is exclusively dependent on the presence of the SQS1 C-terminal hydrophobic trans-membrane domain. PMID:18236008

  13. Momilactone sensitive proteins in Arabidopsis thaliana.

    PubMed

    Kato-Noguchi, Hisashi; Kitajima, Shinya

    2015-05-01

    The labdane-related diterpenoid, momilactone B has potent growth inhibitory activity and was demonstrated to play a particularly critical role in the allelopathy of rice (Oryza sativa L.). However, there is limited information available about the mode of action of momilactone B on the growth inhibition. The present research describes the effects of momilactone B on protein expression in the early development of Arabidopsis thaliana seedling, which was determined by two-dimensional electrophoresis and MALDI-TOFMS. Momilactone B inhibited the accumulation of subtilisin-like serine protease, amyrin synthase LUP2, β-glucosidase and malate synthase at 1 h after the momilactone application. Those proteins are involved in the metabolic turnover and the production of intermediates needed for cell structures resulting in plant growth and development. Momilactone B also inhibited the breakdown of cruciferin 2, which is essential for seed germination and seedling growth to construct cell structures. Momilactone B induced the accumulation of translationally controlled tumor protein, glutathione S-transferase and 1-cysteine peroxiredoxin 1. These proteins are involved in stress responses and increased stress tolerance. In addition, glutathione S-transferase has the activity of herbicide detoxification and 1-cysteine peroxiredoxin 1 has inhibitory activity for seed germination under unfavorable conditions. The present research suggests that momilactone B may inhibit the seedling growth by the inhibition of the metabolic turnover and the production of intermediates for cell structures. In addition, momilactone induced proteins associated with plant defense responses. PMID:26058145

  14. Mutants of Arabidopsis thaliana with altered phototropism

    NASA Technical Reports Server (NTRS)

    Khurana, J. P.; Poff, K. L.

    1989-01-01

    Thirty five strains of Arabidopsis thaliana (L.) Heynh. have been identified with altered phototropic responses to 450-nm light. Four of these mutants have been more thoroughly characterized. Strain JK224 shows normal gravitropism and "second positive" phototropism. However, while the amplitude for "first positive" phototropism is the same as that in the wild-type, the threshold and fluence for the maximum response in "first positive" phototropism are shifted to higher fluence by a factor of 20-30. This mutant may represent an alteration in the photoreceptor pigment for phototropism. Strain JK218 exhibits no curvature to light at any fluence from 1 micromole m-2 to 2700 micromoles m-2, but shows normal gravitropism. Strain JK345 shows no "first positive" phototropism, and reduced gravitropism and "second positive" phototropism. Strain JK229 shows no measurable "first positive" phototropism, but normal gravitropism and "second positive" phototropism. Based on these data, it is suggested that: 1. gravitropism and phototropism contain at least one common element; 2. "first positive" and "second positive" phototropism contain at least one common element; and 3. "first positive" phototropism can be substantially altered without any apparent alteration of "second positive" phototropism.

  15. Metabolic profiling of Arabidopsis thaliana epidermal cells

    PubMed Central

    Ebert, Berit; Zöller, Daniela; Erban, Alexander; Fehrle, Ines; Hartmann, Jürgen; Niehl, Annette; Kopka, Joachim; Fisahn, Joachim

    2010-01-01

    Metabolic phenotyping at cellular resolution may be considered one of the challenges in current plant physiology. A method is described which enables the cell type-specific metabolic analysis of epidermal cell types in Arabidopsis thaliana pavement, basal, and trichome cells. To achieve the required high spatial resolution, single cell sampling using microcapillaries was combined with routine gas chromatography-time of flight-mass spectrometry (GC-TOF-MS) based metabolite profiling. The identification and relative quantification of 117 mostly primary metabolites has been demonstrated. The majority, namely 90 compounds, were accessible without analytical background correction. Analyses were performed using cell type-specific pools of 200 microsampled individual cells. Moreover, among these identified metabolites, 38 exhibited differential pool sizes in trichomes, basal or pavement cells. The application of an independent component analysis confirmed the cell type-specific metabolic phenotypes. Significant pool size changes between individual cells were detectable within several classes of metabolites, namely amino acids, fatty acids and alcohols, alkanes, lipids, N-compounds, organic acids and polyhydroxy acids, polyols, sugars, sugar conjugates and phenylpropanoids. It is demonstrated here that the combination of microsampling and GC-MS based metabolite profiling provides a method to investigate the cellular metabolism of fully differentiated plant cell types in vivo. PMID:20150518

  16. Genetics of water use physiology in locally adapted Arabidopsis thaliana.

    PubMed

    Mojica, Julius P; Mullen, Jack; Lovell, John T; Monroe, J Grey; Paul, John R; Oakley, Christopher G; McKay, John K

    2016-10-01

    Identifying the genetic basis of adaptation to climate has long been a goal in evolutionary biology and has applications in agriculture. Adaptation to drought represents one important aspect of local adaptation, and drought is the major factor limiting agricultural yield. We examined local adaptation between Sweden and Italy Arabidopsis thaliana ecotypes, which show contrasting levels of water availability in their local environments. To identify quantitative trait loci (QTL) controlling water use physiology traits and adaptive trait QTL (genomic regions where trait QTL and fitness QTL colocalize), we performed QTL mapping on 374F9 recombinant inbred lines in well-watered and terminal drought conditions. We found 72 QTL (32 in well-watered, 31 in drought, 9 for plasticity) across five water use physiology traits: δ(13)C, rosette area, dry rosette weight, leaf water content and percent leaf nitrogen. Some of these genomic regions colocalize with fitness QTL and with other physiology QTL in defined hotspots. In addition, we found evidence of both constitutive and inducible water use physiology QTL. Finally, we identified highly divergent candidate genes, in silico. Our results suggest that many genes with minor effects may influence adaptation through water use physiology and that pleiotropic water use physiology QTL have fitness consequences. PMID:27593459

  17. [Arabidopsis thaliana accessions - a tool for biochemical and phylogentical studies].

    PubMed

    Szymańska, Renata; Gabruk, Michał; Kruk, Jerzy

    2015-01-01

    Arabidopsis thaliana since a few decades is used as a model for biological and plant genetic research. Natural variation of this species is related to its geographical range which covers different climate zones and habitats. The ability to occupy such a wide area by Arabidopsis is possible due to its stress tolerance and adaptability. Arabidopsis accessions exhibit phenotypic and genotypic variation, which is a result of adaptation to local environmental conditions. During development, plants are subjected to various stress factors. Plants show a spectrum of reactions, processes and phenomena that determine their survival in these adverse conditions. The response of plants to stress involves signal detection and transmission. These reactions are different and depend on the stressor, its intensity, plant species and life strategy. It is assumed that the populations of the same species from different geographical regions acclimated to the stress conditions develop a set of alleles, which allow them to grow and reproduce. Therefore, the study of natural variation in response to abiotic stress among Arabidopsis thaliana accessions allows to find key genes or alleles, and thus the mechanisms by which plants cope with adverse physical and chemical conditions. This paper presents an overview of recent findings, tools and research directions used in the study of natural variation in Arabidopsis thaliana accessions. Additionally, we explain why accessions can be used in the phylogenetic analyses and to study demography and migration of Arabidopsis thaliana. PMID:26281359

  18. Key Proliferative Activity in the Junction between the Leaf Blade and Leaf Petiole of Arabidopsis1[W][OA

    PubMed Central

    Ichihashi, Yasunori; Kawade, Kensuke; Usami, Takeshi; Horiguchi, Gorou; Takahashi, Taku; Tsukaya, Hirokazu

    2011-01-01

    Leaves are the most important, fundamental units of organogenesis in plants. Although the basic form of a leaf is clearly divided into the leaf blade and leaf petiole, no study has yet revealed how these are differentiated from a leaf primordium. We analyzed the spatiotemporal pattern of mitotic activity in leaf primordia of Arabidopsis (Arabidopsis thaliana) in detail using molecular markers in combination with clonal analysis. We found that the proliferative zone is established after a short interval following the occurrence of a rod-shaped early leaf primordium; it is separated spatially from the shoot apical meristem and seen at the junction region between the leaf blade and leaf petiole and produces both leaf-blade and leaf-petiole cells. This proliferative region in leaf primordia is marked by activity of the ANGUSTIFOLIA3 (AN3) promoter as a whole and seems to be differentiated into several spatial compartments: activities of the CYCLIN D4;2 promoter and SPATULA enhancer mark parts of it specifically. Detailed analyses of the an3 and blade-on-petiole mutations further support the idea that organogenesis of the leaf blade and leaf petiole is critically dependent on the correct spatial regulation of the proliferative region of leaf primordia. Thus, the proliferative zone of leaf primordia is spatially differentiated and supplies both the leaf-blade and leaf-petiole cells. PMID:21880932

  19. A Mutation in Plant-Specific SWI2/SNF2-Like Chromatin-Remodeling Proteins, DRD1 and DDM1, Delays Leaf Senescence in Arabidopsis thaliana

    PubMed Central

    Kim, Ji Hong; Kim, Ji Eun; Lee, Min Hee; Chung, Byung Yeoup; Woo, Hye Ryun; Kim, Jin-Hong

    2016-01-01

    Leaf senescence is a finely regulated complex process; however, evidence for the involvement of epigenetic processes in the regulation of leaf senescence is still fragmentary. Therefore, we chose to examine the functions of DRD1, a SWI2/SNF2 chromatin remodeling protein, in epigenetic regulation of leaf senescence, particularly because drd1-6 mutants exhibited a delayed leaf senescence phenotype. Photosynthetic parameters such as Fv/Fm and ETRmax were decreased in WT leaves compared to leaves of drd1-6 mutants after dark treatment. The WT leaves remarkably lost more chlorophyll and protein content during dark-induced senescence (DIS) than the drd1-6 leaves did. The induction of senescence-associated genes was noticeably inhibited in the drd1-6 mutant after 5-d of DIS. We compared changes in epigenetic regulation during DIS via quantitative expression analysis of 180-bp centromeric (CEN) and transcriptionally silent information (TSI) repeats. Their expression levels significantly increased in both the WT and the drd1-6 mutant, but did much less in the latter. Moreover, the delayed leaf senescence was observed in ddm1-2 mutants as well as the drd1-6, but not in drd1-p mutants. These data suggest that SWI2/SNF2 chromatin remodeling proteins such as DRD1 and DDM1 may influence leaf senescence possibly via epigenetic regulation. PMID:26752684

  20. Monitoring of isothiocyanates emanating from Arabidopsis thaliana upon paraquat spraying.

    PubMed

    Vercammen, J; Pham-Tuan, H; Arickx, I; Van der Straeten, D; Sandra, P

    2001-03-30

    Arabidopsis thaliana plants were sprayed with the superoxide-generating herbicide paraquat. The headspace of sprayed plants was characterized by a number of compounds, which were absent in the headspace of untreated plants. They were identified as isothiocyanates (ITCs) with 4-methylthiobutyl isothiocyanate as main compound. After identification, a GC-system, based on PDMS sorption, was used to continuously monitor the ITC emissions. The specificity of isothiocyanate emission was also determined by subjecting the Arabidopsis thaliana plants to in vitro mechanical wounding. Again, 4-methylthiobutyl isothiocyanate was the main component, but the emission profile was completely different since the compound was emitted immediately, i.e., during wounding itself. PMID:11307975

  1. Genetic analysis of natural variations in the architecture of Arabidopsis thaliana vegetative leaves.

    PubMed Central

    Pérez-Pérez, José Manuel; Serrano-Cartagena, José; Micol, José Luis

    2002-01-01

    To ascertain whether intraspecific variability might be a source of information as regards the genetic controls underlying plant leaf morphogenesis, we analyzed variations in the architecture of vegetative leaves in a large sample of Arabidopsis thaliana natural races. A total of 188 accessions from the Arabidopsis Information Service collection were grown and qualitatively classified into 14 phenotypic classes, which were defined according to petiole length, marginal configuration, and overall lamina shape. Accessions displaying extreme and opposite variations in the above-mentioned leaf architectural traits were crossed and their F(2) progeny was found to be not classifiable into discrete phenotypic classes. Furthermore, the leaf trait-based classification was not correlated with estimates on the genetic distances between the accessions being crossed, calculated after determining variations in repeat number at 22 microsatellite loci. Since these results suggested that intraspecific variability in A. thaliana leaf morphology arises from an accumulation of mutations at quantitative trait loci (QTL), we studied a mapping population of recombinant inbred lines (RILs) derived from a Landsberg erecta-0 x Columbia-4 cross. A total of 100 RILs were grown and the third and seventh leaves of 15 individuals from each RIL were collected and morphometrically analyzed. We identified a total of 16 and 13 QTL harboring naturally occurring alleles that contribute to natural variations in the architecture of juvenile and adult leaves, respectively. Our QTL mapping results confirmed the multifactorial nature of the observed natural variations in leaf architecture. PMID:12399398

  2. Photosynthetic lesions can trigger accelerated senescence in Arabidopsis thaliana

    PubMed Central

    Wang, Jing; Leister, Dario; Bolle, Cordelia

    2015-01-01

    Senescence is a highly regulated process characterized by the active breakdown of cells, which ultimately leads to the death of plant organs or whole plants. In annual plants such as Arabidopsis thaliana senescence can be observed in each individual leaf. Whether deficiencies in photosynthesis promote the induction of senescence was investigated by monitoring chlorophyll degradation, photosynthetic parameters, and reactive oxygen species accumulation in photosynthetic mutants. Several mutations affecting components of the photosynthetic apparatus, including psal-2, psan-2, and psbs, were found to lead to premature or faster senescence, as did simultaneous inactivation of the STN7 and STN8 kinases. Premature senescence is apparently not directly linked to an overall reduction in photosynthesis but to perturbations in specific aspects of the process. Dark-induced senescence is accelerated in mutants affected in linear electron flow, especially psad2-1, psan-2, and pete2-1, as well as in stn7 and stn8 mutants and STN7 and STN8 overexpressor lines. Interestingly, no direct link with ROS production could be observed. PMID:26272903

  3. Proteomic Responses in Arabidopsis thaliana Seedlings Treated with Ethylene

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ethylene (ET) is a volatile plant growth hormone that most famously modulates fruit ripening, but it also controls plant growth, development and stress responses. In Arabidopsis thaliana, ET is perceived by receptors in the endoplasmic reticulum, and a signal is transduced through a protein kinase,...

  4. VERMICULITE, A SOURCE OF METALS FOR 'ARABIDOPSIS THALIANA'

    EPA Science Inventory

    Plants of Arabidopsis thaliana (L.) Heynh. were grown in hydroponic systems using vermiculite as a growth medium at nutrition levels ranging from adequate to deficient. Plants grown on the low-total nutrient or low-iron nutrient contained more of iron, magnesium, and aluminum, fr...

  5. An Arabidopsis thaliana embryo arrest mutant exhibiting germination potential

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability to initiate radicle elongation, or germination potential, occurs in developing embryos before the completion of seed maturation. Green embryos after walking-stick stage in developing Arabidopsis thaliana seeds germinate when excised from seeds and incubated in MS media containing 1 % suc...

  6. Small Glycosylated Lignin Oligomers Are Stored in Arabidopsis Leaf Vacuoles

    PubMed Central

    Dima, Oana; Morreel, Kris; Vanholme, Bartel; Kim, Hoon; Ralph, John; Boerjan, Wout

    2015-01-01

    Lignin is an aromatic polymer derived from the combinatorial coupling of monolignol radicals in the cell wall. Recently, various glycosylated lignin oligomers have been revealed in Arabidopsis thaliana. Given that monolignol oxidation and monolignol radical coupling are known to occur in the apoplast, and glycosylation in the cytoplasm, it raises questions about the subcellular localization of glycosylated lignin oligomer biosynthesis and their storage. By metabolite profiling of Arabidopsis leaf vacuoles, we show that the leaf vacuole stores a large number of these small glycosylated lignin oligomers. Their structural variety and the incorporation of alternative monomers, as observed in Arabidopsis mutants with altered monolignol biosynthesis, indicate that they are all formed by combinatorial radical coupling. In contrast to the common believe that combinatorial coupling is restricted to the apoplast, we hypothesized that the aglycones of these compounds are made within the cell. To investigate this, leaf protoplast cultures were cofed with 13C6-labeled coniferyl alcohol and a 13C4-labeled dimer of coniferyl alcohol. Metabolite profiling of the cofed protoplasts provided strong support for the occurrence of intracellular monolignol coupling. We therefore propose a metabolic pathway involving intracellular combinatorial coupling of monolignol radicals, followed by oligomer glycosylation and vacuolar import, which shares characteristics with both lignin and lignan biosynthesis. PMID:25700483

  7. Arabidopsis thaliana ggt1 photorespiratory mutants maintain leaf carbon/nitrogen balance by reducing RuBisCO content and plant growth.

    PubMed

    Dellero, Younès; Lamothe-Sibold, Marlène; Jossier, Mathieu; Hodges, Michael

    2015-09-01

    Metabolic and physiological analyses of glutamate:glyoxylate aminotransferase 1 (GGT1) mutants were performed at the global leaf scale to elucidate the mechanisms involved in their photorespiratory growth phenotype. Air-grown ggt1 mutants showed retarded growth and development, that was not observed at high CO2 (3000 μL L(-1) ). When compared to wild-type (WT) plants, air-grown ggt1 plants exhibited glyoxylate accumulation, global changes in amino acid amounts including a decrease in serine content, lower organic acid levels, and modified ATP/ADP and NADP(+) /NADPH ratios. When compared to WT plants, their net CO2 assimilation rates (An ) were 50% lower and this mirrored decreases in ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) contents. High CO2 -grown ggt1 plants transferred to air revealed a rapid decrease of An and photosynthetic electron transfer rate while maintaining a high energetic state. Short-term (a night period and 4 h of light) transferred ggt1 leaves accumulated glyoxylate and exhibited low serine contents, while other amino acid levels were not modified. RuBisCO content, activity and activation state were not altered after a short-term transfer while the ATP/ADP ratio was lowered in ggt1 rosettes. However, plant growth and RuBisCO levels were both reduced in ggt1 leaves after a long-term (12 days) acclimation to air from high CO2 when compared to WT plants. The data are discussed with respect to a reduced photorespiratory carbon recycling in the mutants. It is proposed that the low An limits nitrogen-assimilation, this decreases leaf RuBisCO content until plants attain a new homeostatic state that maintains a constant C/N balance and leads to smaller, slower growing plants. PMID:26216646

  8. Planting molecular functions in an ecological context with Arabidopsis thaliana

    PubMed Central

    Krämer, Ute

    2015-01-01

    The vascular plant Arabidopsis thaliana is a central genetic model and universal reference organism in plant and crop science. The successful integration of different fields of research in the study of A. thaliana has made a large contribution to our molecular understanding of key concepts in biology. The availability and active development of experimental tools and resources, in combination with the accessibility of a wealth of cumulatively acquired knowledge about this plant, support the most advanced systems biology approaches among all land plants. Research in molecular ecology and evolution has also brought the natural history of A. thaliana into the limelight. This article showcases our current knowledge of the natural history of A. thaliana from the perspective of the most closely related plant species, providing an evolutionary framework for interpreting novel findings and for developing new hypotheses based on our knowledge of this plant. DOI: http://dx.doi.org/10.7554/eLife.06100.001 PMID:25807084

  9. Strigolactone Regulates Leaf Senescence in Concert with Ethylene in Arabidopsis.

    PubMed

    Ueda, Hiroaki; Kusaba, Makoto

    2015-09-01

    Leaf senescence is not a passive degenerative process; it represents a process of nutrient relocation, in which materials are salvaged for growth at a later stage or to produce the next generation. Leaf senescence is regulated by various factors, such as darkness, stress, aging, and phytohormones. Strigolactone is a recently identified phytohormone, and it has multiple functions in plant development, including repression of branching. Although strigolactone is implicated in the regulation of leaf senescence, little is known about its molecular mechanism of action. In this study, strigolactone biosynthesis mutant strains of Arabidopsis (Arabidopsis thaliana) showed a delayed senescence phenotype during dark incubation. The strigolactone biosynthesis genes MORE AXIALLY GROWTH3 (MAX3) and MAX4 were drastically induced during dark incubation and treatment with the senescence-promoting phytohormone ethylene, suggesting that strigolactone is synthesized in the leaf during leaf senescence. This hypothesis was confirmed by a grafting experiment using max4 as the stock and Columbia-0 as the scion, in which the leaves from the Columbia-0 scion senesced earlier than max4 stock leaves. Dark incubation induced the synthesis of ethylene independent of strigolactone. Strigolactone biosynthesis mutants showed a delayed senescence phenotype during ethylene treatment in the light. Furthermore, leaf senescence was strongly accelerated by the application of strigolactone in the presence of ethylene and not by strigolactone alone. These observations suggest that strigolactone promotes leaf senescence by enhancing the action of ethylene. Thus, dark-induced senescence is regulated by a two-step mechanism: induction of ethylene synthesis and consequent induction of strigolactone synthesis in the leaf. PMID:25979917

  10. Reversal of senescence by N resupply to N-starved Arabidopsis thaliana: transcriptomic and metabolomic consequences

    PubMed Central

    Balazadeh, Salma; Schildhauer, Jörg; Araújo, Wagner L.; Munné-Bosch, Sergi; Fernie, Alisdair R.; Proost, Sebastian; Humbeck, Klaus; Mueller-Roeber, Bernd

    2014-01-01

    Leaf senescence is a developmentally controlled process, which is additionally modulated by a number of adverse environmental conditions. Nitrogen shortage is a well-known trigger of precocious senescence in many plant species including crops, generally limiting biomass and seed yield. However, leaf senescence induced by nitrogen starvation may be reversed when nitrogen is resupplied at the onset of senescence. Here, the transcriptomic, hormonal, and global metabolic rearrangements occurring during nitrogen resupply-induced reversal of senescence in Arabidopsis thaliana were analysed. The changes induced by senescence were essentially in keeping with those previously described; however, these could, by and large, be reversed. The data thus indicate that plants undergoing senescence retain the capacity to sense and respond to the availability of nitrogen nutrition. The combined data are discussed in the context of the reversibility of the senescence programme and the evolutionary benefit afforded thereby. Future prospects for understanding and manipulating this process in both Arabidopsis and crop plants are postulated. PMID:24692653

  11. Dated molecular phylogenies indicate a Miocene origin for Arabidopsis thaliana.

    PubMed

    Beilstein, Mark A; Nagalingum, Nathalie S; Clements, Mark D; Manchester, Steven R; Mathews, Sarah

    2010-10-26

    Dated molecular phylogenies are the basis for understanding species diversity and for linking changes in rates of diversification with historical events such as restructuring in developmental pathways, genome doubling, or dispersal onto a new continent. Valid fossil calibration points are essential to the accurate estimation of divergence dates, but for many groups of flowering plants fossil evidence is unavailable or limited. Arabidopsis thaliana, the primary genetic model in plant biology and the first plant to have its entire genome sequenced, belongs to one such group, the plant family Brassicaceae. Thus, the timing of A. thaliana evolution and the history of its genome have been controversial. We bring previously overlooked fossil evidence to bear on these questions and find the split between A. thaliana and Arabidopsis lyrata occurred about 13 Mya, and that the split between Arabidopsis and the Brassica complex (broccoli, cabbage, canola) occurred about 43 Mya. These estimates, which are two- to threefold older than previous estimates, indicate that gene, genomic, and developmental evolution occurred much more slowly than previously hypothesized and that Arabidopsis evolved during a period of warming rather than of cooling. We detected a 2- to 10-fold shift in species diversification rates on the branch uniting Brassicaceae with its sister families. The timing of this shift suggests a possible impact of the Cretaceous-Paleogene mass extinction on their radiation and that Brassicales codiversified with pierid butterflies that specialize on mustard-oil-producing plants. PMID:20921408

  12. The hidden geometries of the Arabidopsis thaliana epidermis.

    PubMed

    Staff, Lee; Hurd, Patricia; Reale, Lara; Seoighe, Cathal; Rockwood, Alyn; Gehring, Chris

    2012-01-01

    The quest for the discovery of mathematical principles that underlie biological phenomena is ancient and ongoing. We present a geometric analysis of the complex interdigitated pavement cells in the Arabidopsis thaliana (Col.) adaxial epidermis with a view to discovering some geometric characteristics that may govern the formation of this tissue. More than 2,400 pavement cells from 10, 17 and 24 day old leaves were analyzed. These interdigitated cells revealed a number of geometric properties that remained constant across the three age groups. In particular, the number of digits per cell rarely exceeded 15, irrespective of cell area. Digit numbers per 100 µm(2) cell area reduce with age and as cell area increases, suggesting early developmental programming of digits. Cell shape proportions as defined by length:width ratios were highly conserved over time independent of the size and, interestingly, both the mean and the medians were close to the golden ratio 1.618034. With maturity, the cell area:perimeter ratios increased from a mean of 2.0 to 2.4. Shape properties as defined by the medial axis transform (MAT) were calculated and revealed that branch points along the MAT typically comprise one large and two small angles. These showed consistency across the developmental stages considered here at 140° (± 5°) for the largest angles and 110° (± 5°) for the smaller angles. Voronoi diagram analyses of stomatal center coordinates revealed that giant pavement cells (≥ 500 µm(2)) tend to be arranged along Voronoi boundaries suggesting that they could function as a scaffold of the epidermis. In addition, we propose that pavement cells have a role in spacing and positioning of the stomata in the growing leaf and that they do so by growing within the limits of a set of 'geometrical rules'. PMID:22984433

  13. Zinc triggers signaling mechanisms and defense responses promoting resistance to Alternaria brassicicola in Arabidopsis thaliana.

    PubMed

    Martos, Soledad; Gallego, Berta; Cabot, Catalina; Llugany, Mercè; Barceló, Juan; Poschenrieder, Charlotte

    2016-08-01

    According to the elemental defense hypothesis the accumulation of trace elements by plants may substitute for organic defenses, while the joint effects hypothesis proposes that trace elements and organic defenses can have additive or synergistic effects against pathogens or herbivores. To evaluate these hypotheses the response of the pathosystem Alternaria brassicicola-Arabidopsis thaliana to control (2μM) and surplus (12μM) Zn was evaluated using the camalexin deficient mutant pad3-1 and mtp1-1, a mutant with impaired Zn vacuolar storage, along with the corresponding wildtypes. In vitro, a 50% inhibition of fungal growth was achieved by 440μM Zn. A. thaliana leaves could accumulate equivalent concentrations without harm. In fact, surplus Zn enhanced the resistance of A. thaliana to fungal attack in Columbia (Col-0), Wassilewskija (WS), and mtp1-1. However, surplus Zn was unable to protect pad3-1 demonstrating that Zn cannot substitute for camalexin, the main organic defense in A. thaliana. High, non phytotoxic leaf Zn concentrations enhanced the resistance to A. brassicicola of A. thaliana genotypes able to produce camalexin. This was mainly due to Zn-induced enhancement of the JA/ETH signaling pathway leading to enhanced PAD3 expression. These results support the joint effects hypothesis and highlight the importance of adequate Zn supply for reinforced pathogen resistance. PMID:27297986

  14. Gibberellins control fruit patterning in Arabidopsis thaliana

    PubMed Central

    Arnaud, Nicolas; Girin, Thomas; Sorefan, Karim; Fuentes, Sara; Wood, Thomas A.; Lawrenson, Tom; Sablowski, Robert; Østergaard, Lars

    2010-01-01

    The Arabidopsis basic helix–loop–helix (bHLH) proteins INDEHISCENT (IND) and ALCATRAZ (ALC) specify tissues required for fruit opening that have major roles in seed dispersal and plant domestication. Here, we show that synthesis of the phytohormone gibberellin is a direct and necessary target of IND, and that ALC interacts directly with DELLA repressors, which antagonize ALC function but are destabilized by gibberellin. Thus, the gibberellin/DELLA pathway has a key role in patterning the Arabidopsis fruit, and the interaction between DELLA and bHLH proteins, previously shown to connect gibberellin and light responses, is a versatile regulatory module also used in tissue patterning. PMID:20889713

  15. Gibberellins control fruit patterning in Arabidopsis thaliana.

    PubMed

    Arnaud, Nicolas; Girin, Thomas; Sorefan, Karim; Fuentes, Sara; Wood, Thomas A; Lawrenson, Tom; Sablowski, Robert; Østergaard, Lars

    2010-10-01

    The Arabidopsis basic helix-loop-helix (bHLH) proteins INDEHISCENT (IND) and ALCATRAZ (ALC) specify tissues required for fruit opening that have major roles in seed dispersal and plant domestication. Here, we show that synthesis of the phytohormone gibberellin is a direct and necessary target of IND, and that ALC interacts directly with DELLA repressors, which antagonize ALC function but are destabilized by gibberellin. Thus, the gibberellin/DELLA pathway has a key role in patterning the Arabidopsis fruit, and the interaction between DELLA and bHLH proteins, previously shown to connect gibberellin and light responses, is a versatile regulatory module also used in tissue patterning. PMID:20889713

  16. Demographic History of European Populations of Arabidopsis thaliana

    PubMed Central

    François, Olivier; Blum, Michael G. B.; Jakobsson, Mattias; Rosenberg, Noah A.

    2008-01-01

    The model plant species Arabidopsis thaliana is successful at colonizing land that has recently undergone human-mediated disturbance. To investigate the prehistoric spread of A. thaliana, we applied approximate Bayesian computation and explicit spatial modeling to 76 European accessions sequenced at 876 nuclear loci. We find evidence that a major migration wave occurred from east to west, affecting most of the sampled individuals. The longitudinal gradient appears to result from the plant having spread in Europe from the east ∼10,000 years ago, with a rate of westward spread of ∼0.9 km/year. This wave-of-advance model is consistent with a natural colonization from an eastern glacial refugium that overwhelmed ancient western lineages. However, the speed and time frame of the model also suggest that the migration of A. thaliana into Europe may have accompanied the spread of agriculture during the Neolithic transition. PMID:18483550

  17. Multiple reference genomes and transcriptomes for Arabidopsis thaliana.

    PubMed

    Gan, Xiangchao; Stegle, Oliver; Behr, Jonas; Steffen, Joshua G; Drewe, Philipp; Hildebrand, Katie L; Lyngsoe, Rune; Schultheiss, Sebastian J; Osborne, Edward J; Sreedharan, Vipin T; Kahles, André; Bohnert, Regina; Jean, Géraldine; Derwent, Paul; Kersey, Paul; Belfield, Eric J; Harberd, Nicholas P; Kemen, Eric; Toomajian, Christopher; Kover, Paula X; Clark, Richard M; Rätsch, Gunnar; Mott, Richard

    2011-09-22

    Genetic differences between Arabidopsis thaliana accessions underlie the plant's extensive phenotypic variation, and until now these have been interpreted largely in the context of the annotated reference accession Col-0. Here we report the sequencing, assembly and annotation of the genomes of 18 natural A. thaliana accessions, and their transcriptomes. When assessed on the basis of the reference annotation, one-third of protein-coding genes are predicted to be disrupted in at least one accession. However, re-annotation of each genome revealed that alternative gene models often restore coding potential. Gene expression in seedlings differed for nearly half of expressed genes and was frequently associated with cis variants within 5 kilobases, as were intron retention alternative splicing events. Sequence and expression variation is most pronounced in genes that respond to the biotic environment. Our data further promote evolutionary and functional studies in A. thaliana, especially the MAGIC genetic reference population descended from these accessions. PMID:21874022

  18. Re-Evaluation of Reportedly Metal Tolerant Arabidopsis thaliana Accessions.

    PubMed

    Silva-Guzman, Macarena; Addo-Quaye, Charles; Dilkes, Brian P

    2016-01-01

    Santa Clara, Limeport, and Berkeley are Arabidopsis thaliana accessions previously identified as diversely metal resistant. Yet these same accessions were determined to be genetically indistinguishable from the metal sensitive Col-0. We robustly tested tolerance for Zn, Ni and Cu, and genetic relatedness by growing these accessions under a range of Ni, Zn and Cu concentrations for three durations in multiple replicates. Neither metal resistance nor variance in growth were detected between them and Col-0. We re-sequenced the genomes of these accessions and all stocks available for each accession. In all cases they were nearly indistinguishable from the standard laboratory accession Col-0. As Santa Clara was allegedly collected from the Jasper Ridge serpentine outcrop in California, USA we investigated the possibility of extant A. thaliana populations adapted to serpentine soils. Botanically vouchered Arabidopsis accessions in the Jepson database were overlaid with soil maps of California. This provided no evidence of A. thaliana collections from serpentine sites in California. Thus, our work demonstrates that the Santa Clara, Berkeley and Limeport accessions are not metal tolerant, not genetically distinct from Col-0, and that there are no known serpentine adapted populations or accessions of A. thaliana. PMID:27467746

  19. Nucleosome structure incorporated histone acetylation site prediction in arabidopsis thaliana

    PubMed Central

    2010-01-01

    Abstract Background Acetylation is a crucial post-translational modification for histones, and plays a key role in gene expression regulation. Due to limited data and lack of a clear acetylation consensus sequence, a few researches have focused on prediction of lysine acetylation sites. Several systematic prediction studies have been conducted for human and yeast, but less for Arabidopsis thaliana. Results Concerning the insufficient observation on acetylation site, we analyzed contributions of the peptide-alignment-based distance definition and 3D structure factors in acetylation prediction. We found that traditional structure contributes little to acetylation site prediction. Identified acetylation sites of histones in Arabidopsis thaliana are conserved and cross predictable with that of human by peptide based methods. However, the predicted specificity is overestimated, because of the existence of non-observed acetylable site. Here, by performing a complete exploration on the factors that affect the acetylability of lysines in histones, we focused on the relative position of lysine at nucleosome level, and defined a new structure feature to promote the performance in predicting the acetylability of all the histone lysines in A. thaliana. Conclusion We found a new spacial correlated acetylation factor, and defined a ε-N spacial location based feature, which contains five core spacial ellipsoid wired areas. By incorporating the new feature, the performance of predicting the acetylability of all the histone lysines in A. Thaliana was promoted, in which the previous mispredicted acetylable lysines were corrected by comparing to the peptide-based prediction. PMID:21047388

  20. Re-Evaluation of Reportedly Metal Tolerant Arabidopsis thaliana Accessions

    PubMed Central

    Silva-Guzman, Macarena; Addo-Quaye, Charles; Dilkes, Brian P.

    2016-01-01

    Santa Clara, Limeport, and Berkeley are Arabidopsis thaliana accessions previously identified as diversely metal resistant. Yet these same accessions were determined to be genetically indistinguishable from the metal sensitive Col-0. We robustly tested tolerance for Zn, Ni and Cu, and genetic relatedness by growing these accessions under a range of Ni, Zn and Cu concentrations for three durations in multiple replicates. Neither metal resistance nor variance in growth were detected between them and Col-0. We re-sequenced the genomes of these accessions and all stocks available for each accession. In all cases they were nearly indistinguishable from the standard laboratory accession Col-0. As Santa Clara was allegedly collected from the Jasper Ridge serpentine outcrop in California, USA we investigated the possibility of extant A. thaliana populations adapted to serpentine soils. Botanically vouchered Arabidopsis accessions in the Jepson database were overlaid with soil maps of California. This provided no evidence of A. thaliana collections from serpentine sites in California. Thus, our work demonstrates that the Santa Clara, Berkeley and Limeport accessions are not metal tolerant, not genetically distinct from Col-0, and that there are no known serpentine adapted populations or accessions of A. thaliana. PMID:27467746

  1. Chrysanthemum transcription factor CmLBD1 direct lateral root formation in Arabidopsis thaliana.

    PubMed

    Zhu, Lu; Zheng, Chen; Liu, Ruixia; Song, Aiping; Zhang, Zhaohe; Xin, Jingjing; Jiang, Jiafu; Chen, Sumei; Zhang, Fei; Fang, Weimin; Chen, Fadi

    2016-01-01

    The plant-specific LATERAL ORGAN BOUNDARIES DOMAIN (LBD) genes are important regulators of growth and development. Here, a chrysanthemum class I LBD transcription factor gene, designated CmLBD1, was isolated and its function verified. CmLBD1 was transcribed in both the root and stem, but not in the leaf. The gene responded to auxin and was shown to participate in the process of adventitious root primordium formation. Its heterologous expression in Arabidopsis thaliana increased the number of lateral roots formed. When provided with exogenous auxin, lateral root emergence was promoted. CmLBD1 expression also favored callus formation from A. thaliana root explants in the absence of exogenously supplied phytohormones. In planta, CmLBD1 probably acts as a positive regulator of the response to auxin fluctuations and connects auxin signaling with lateral root formation. PMID:26819087

  2. Chrysanthemum transcription factor CmLBD1 direct lateral root formation in Arabidopsis thaliana

    PubMed Central

    Zhu, Lu; Zheng, Chen; Liu, Ruixia; Song, Aiping; Zhang, Zhaohe; Xin, Jingjing; Jiang, Jiafu; Chen, Sumei; Zhang, Fei; Fang, Weimin; Chen, Fadi

    2016-01-01

    The plant-specific LATERAL ORGAN BOUNDARIES DOMAIN (LBD) genes are important regulators of growth and development. Here, a chrysanthemum class I LBD transcription factor gene, designated CmLBD1, was isolated and its function verified. CmLBD1 was transcribed in both the root and stem, but not in the leaf. The gene responded to auxin and was shown to participate in the process of adventitious root primordium formation. Its heterologous expression in Arabidopsis thaliana increased the number of lateral roots formed. When provided with exogenous auxin, lateral root emergence was promoted. CmLBD1 expression also favored callus formation from A. thaliana root explants in the absence of exogenously supplied phytohormones. In planta, CmLBD1 probably acts as a positive regulator of the response to auxin fluctuations and connects auxin signaling with lateral root formation. PMID:26819087

  3. pATsi: Paralogs and Singleton Genes from Arabidopsis thaliana

    PubMed Central

    Ambrosino, Luca; Bostan, Hamed; di Salle, Pasquale; Sangiovanni, Mara; Vigilante, Alessandra; Chiusano, Maria L.

    2016-01-01

    Arabidopsis thaliana is widely accepted as a model species in plant biology. Its genome, due to its small size and diploidy, was the first to be sequenced among plants, making this species also a reference for plant comparative genomics. Nevertheless, the evolutionary mechanisms that shaped the Arabidopsis genome are still controversial. Indeed, duplications, translocations, inversions, and gene loss events that contributed to the current organization are difficult to be traced. A reliable identification of paralogs and single-copy genes is essential to understand these mechanisms. Therefore, we implemented a dedicated pipeline to identify paralog genes and classify single-copy genes into opportune categories. PATsi, a web-accessible database, was organized to allow the straightforward access to the paralogs organized into networks and to the classification of single-copy genes. This permits to efficiently explore the gene collection of Arabidopsis for evolutionary investigations and comparative genomics. PMID:26792975

  4. Phosphorylation of plastoglobular proteins in Arabidopsis thaliana.

    PubMed

    Lohscheider, Jens N; Friso, Giulia; van Wijk, Klaas J

    2016-06-01

    Plastoglobules (PGs) are plastid lipid-protein particles with a small specialized proteome and metabolome. Among the 30 core PG proteins are six proteins of the ancient ABC1 atypical kinase (ABC1K) family and their locations in an Arabidopsis mRNA-based co-expression network suggested central regulatory roles. To identify candidate ABC1K targets and a possible ABC1K hierarchical phosphorylation network within the chloroplast PG proteome, we searched Arabidopsis phosphoproteomics data from publicly available sources. Evaluation of underlying spectra and/or associated information was challenging for a variety of reasons, but supported pSer sites and a few pThr sites in nine PG proteins, including five FIBRILLINS. PG phosphorylation motifs are discussed in the context of possible responsible kinases. The challenges of collection and evaluation of published Arabidopsis phosphorylation data are discussed, illustrating the importance of deposition of all mass spectrometry data in well-organized repositories such as PRIDE and ProteomeXchange. This study provides a starting point for experimental testing of phosho-sites in PG proteins and also suggests that phosphoproteomics studies specifically designed toward the PG proteome and its ABC1K are needed to understand phosphorylation networks in these specialized particles. PMID:26962209

  5. Phosphorylation of plastoglobular proteins in Arabidopsis thaliana

    PubMed Central

    Lohscheider, Jens N.; Friso, Giulia; van Wijk, Klaas J.

    2016-01-01

    Plastoglobules (PGs) are plastid lipid–protein particles with a small specialized proteome and metabolome. Among the 30 core PG proteins are six proteins of the ancient ABC1 atypical kinase (ABC1K) family and their locations in an Arabidopsis mRNA-based co-expression network suggested central regulatory roles. To identify candidate ABC1K targets and a possible ABC1K hierarchical phosphorylation network within the chloroplast PG proteome, we searched Arabidopsis phosphoproteomics data from publicly available sources. Evaluation of underlying spectra and/or associated information was challenging for a variety of reasons, but supported pSer sites and a few pThr sites in nine PG proteins, including five FIBRILLINS. PG phosphorylation motifs are discussed in the context of possible responsible kinases. The challenges of collection and evaluation of published Arabidopsis phosphorylation data are discussed, illustrating the importance of deposition of all mass spectrometry data in well-organized repositories such as PRIDE and ProteomeXchange. This study provides a starting point for experimental testing of phosho-sites in PG proteins and also suggests that phosphoproteomics studies specifically designed toward the PG proteome and its ABC1K are needed to understand phosphorylation networks in these specialized particles. PMID:26962209

  6. Azospirillum brasilense ameliorates the response of Arabidopsis thaliana to drought mainly via enhancement of ABA levels.

    PubMed

    Cohen, Ana C; Bottini, Rubén; Pontin, Mariela; Berli, Federico J; Moreno, Daniela; Boccanlandro, Hernán; Travaglia, Claudia N; Piccoli, Patricia N

    2015-01-01

    Production of phytohormones is one of the main mechanisms to explain the beneficial effects of plant growth-promoting rhizobacteria (PGPR) such as Azospirillum sp. The PGPRs induce plant growth and development, and reduce stress susceptibility. However, little is known regarding the stress-related phytohormone abscisic acid (ABA) produced by bacteria. We investigated the effects of Azospirillum brasilense Sp 245 strain on Arabidopsis thaliana Col-0 and aba2-1 mutant plants, evaluating the morphophysiological and biochemical responses when watered and in drought. We used an in vitro-grown system to study changes in the root volume and architecture after inoculation with Azospirillum in Arabidopsis wild-type Col-0 and on the mutant aba2-1, during early growth. To examine Arabidopsis development and reproductive success as affected by the bacteria, ABA and drought, a pot experiment using Arabidopsis Col-0 plants was also carried out. Azospirillum brasilense augmented plant biomass, altered root architecture by increasing lateral roots number, stimulated photosynthetic and photoprotective pigments and retarded water loss in correlation with incremented ABA levels. As well, inoculation improved plants seed yield, plants survival, proline levels and relative leaf water content; it also decreased stomatal conductance, malondialdehyde and relative soil water content in plants submitted to drought. Arabidopsis inoculation with A. brasilense improved plants performance, especially in drought. PMID:24796562

  7. Stomatal Density Influences Leaf Water and Leaf Wax D/H Values in Arabidopsis

    NASA Astrophysics Data System (ADS)

    Lee, H.; Feakins, S. J.; Sternberg, L. O.

    2014-12-01

    The hydrogen isotopic composition (δD) of plant leaf wax is a powerful tool to study the hydrology of past and present environments. The δD value of leaf waxes is known to primarily reflect the δD value of source water, modified by biological fractionations commonly summarized as the 'net or apparent' fractionation. It remains a challenge, however, to quantitatively relate the isotopic composition of the end product (wax) back to that of the precursor (water) because multiple isotope effects contributing to the net fractionation are not yet well understood. Transgenic variants have heretofore unexplored potential to isolate individual isotope effects. Here we report the first hydrogen isotopic measurements from transgenic Arabidopsis thaliana plants with calculations of leaf water enrichment, net and biosynthetic fractionation values from measured δD of plant waters and leaf wax n-alkanes. We employed transgenic Arabidopsis leaves, engineered to have different stomatal density, by differential expression of the stomatal growth hormone stomagen. Comparison of variants and wild types allow us to isolate the effects of stomatal density on leaf water and the net fractionation expressed by leaf wax biomarkers. Results show that transgenic leaves with denser pores have more enriched leaf water and leaf wax δD values than wild type and even more so than transgenic leaves with sparse stomata (difference of 10 ‰). Our findings that stomatal density controls leaf water and leaf wax δD values adds insights into the cause of variations in net fractionations between species, as well as suggesting that geological variations in stomatal density may modulate the sedimentary leaf wax δD record. In nature, stomatal density varies between species and environments, and all other factors being equal, this will contribute to variations in fractionations observed. Over geological history, lower stomatal densities occur at times of elevated pCO2; our findings predict reduced leaf

  8. Perturbations in the Primary Metabolism of Tomato and Arabidopsis thaliana Plants Infected with the Soil-Borne Fungus Verticillium dahliae.

    PubMed

    Buhtz, Anja; Witzel, Katja; Strehmel, Nadine; Ziegler, Jörg; Abel, Steffen; Grosch, Rita

    2015-01-01

    The hemibiotrophic soil-borne fungus Verticillium dahliae is a major pathogen of a number of economically important crop species. Here, the metabolic response of both tomato and Arabidopsis thaliana to V. dahliae infection was analysed by first using non-targeted GC-MS profiling. The leaf content of both major cell wall components glucuronic acid and xylose was reduced in the presence of the pathogen in tomato but enhanced in A. thaliana. The leaf content of the two tricarboxylic acid cycle intermediates fumaric acid and succinic acid was increased in the leaf of both species, reflecting a likely higher demand for reducing equivalents required for defence responses. A prominent group of affected compounds was amino acids and based on the targeted analysis in the root, it was shown that the level of 12 and four free amino acids was enhanced by the infection in, respectively, tomato and A. thaliana, with leucine and histidine being represented in both host species. The leaf content of six free amino acids was reduced in the leaf tissue of diseased A. thaliana plants, while that of two free amino acids was raised in the tomato plants. This study emphasizes the role of primary plant metabolites in adaptive responses when the fungus has colonized the plant. PMID:26381754

  9. Perturbations in the Primary Metabolism of Tomato and Arabidopsis thaliana Plants Infected with the Soil-Borne Fungus Verticillium dahliae

    PubMed Central

    Buhtz, Anja; Witzel, Katja; Strehmel, Nadine; Ziegler, Jörg; Abel, Steffen; Grosch, Rita

    2015-01-01

    The hemibiotrophic soil-borne fungus Verticillium dahliae is a major pathogen of a number of economically important crop species. Here, the metabolic response of both tomato and Arabidopsis thaliana to V. dahliae infection was analysed by first using non-targeted GC-MS profiling. The leaf content of both major cell wall components glucuronic acid and xylose was reduced in the presence of the pathogen in tomato but enhanced in A. thaliana. The leaf content of the two tricarboxylic acid cycle intermediates fumaric acid and succinic acid was increased in the leaf of both species, reflecting a likely higher demand for reducing equivalents required for defence responses. A prominent group of affected compounds was amino acids and based on the targeted analysis in the root, it was shown that the level of 12 and four free amino acids was enhanced by the infection in, respectively, tomato and A. thaliana, with leucine and histidine being represented in both host species. The leaf content of six free amino acids was reduced in the leaf tissue of diseased A. thaliana plants, while that of two free amino acids was raised in the tomato plants. This study emphasizes the role of primary plant metabolites in adaptive responses when the fungus has colonized the plant. PMID:26381754

  10. Epigenetic Natural Variation in Arabidopsis thaliana

    PubMed Central

    Jiang, Hongmei; Carrasquillo, Robert; Rabinowicz, Pablo D; Dedhia, Neilay; McCombie, W. Richard; Agier, Nicolas; Bulski, Agnès; Colot, Vincent; Doerge, R.W; Martienssen, Robert A

    2007-01-01

    Cytosine methylation of repetitive sequences is widespread in plant genomes, occurring in both symmetric (CpG and CpNpG) as well as asymmetric sequence contexts. We used the methylation-dependent restriction enzyme McrBC to profile methylated DNA using tiling microarrays of Arabidopsis Chromosome 4 in two distinct ecotypes, Columbia and Landsberg erecta. We also used comparative genome hybridization to profile copy number polymorphisms. Repeated sequences and transposable elements (TEs), especially long terminal repeat retrotransposons, are densely methylated, but one third of genes also have low but detectable methylation in their transcribed regions. While TEs are almost always methylated, genic methylation is highly polymorphic, with half of all methylated genes being methylated in only one of the two ecotypes. A survey of loci in 96 Arabidopsis accessions revealed a similar degree of methylation polymorphism. Within-gene methylation is heritable, but is lost at a high frequency in segregating F2 families. Promoter methylation is rare, and gene expression is not generally affected by differences in DNA methylation. Small interfering RNA are preferentially associated with methylated TEs, but not with methylated genes, indicating that most genic methylation is not guided by small interfering RNA. This may account for the instability of gene methylation, if occasional failure of maintenance methylation cannot be restored by other means. PMID:17579518

  11. Functional divergence in tandemly duplicated Arabidopsis thaliana trypsin inhibitor genes.

    PubMed Central

    Clauss, M J; Mitchell-Olds, T

    2004-01-01

    In multigene families, variation among loci and alleles can contribute to trait evolution. We explored patterns of functional and genetic variation in six duplicated Arabidopsis thaliana trypsin inhibitor (ATTI) loci. We demonstrate significant variation in constitutive and herbivore-induced transcription among ATTI loci that show, on average, 65% sequence divergence. Significant variation in ATTI expression was also found between two molecularly defined haplotype classes. Population genetic analyses for 17 accessions of A. thaliana showed that six ATTI loci arranged in tandem within 10 kb varied 10-fold in nucleotide diversity, from 0.0009 to 0.0110, and identified a minimum of six recombination events throughout the tandem array. We observed a significant peak in nucleotide and indel polymorphism spanning ATTI loci in the interior of the array, due primarily to divergence between the two haplotype classes. Significant deviation from the neutral equilibrium model for individual genes was interpreted within the context of intergene linkage disequilibrium and correlated patterns of functional differentiation. In contrast to the outcrosser Arabidopsis lyrata for which recombination is observed even within ATTI loci, our data suggest that response to selection was slowed in the inbreeding, annual A. thaliana because of interference among functionally divergent ATTI loci. PMID:15082560

  12. Verticillium Suppression Is Associated with the Glucosinolate Composition of Arabidopsis thaliana Leaves

    PubMed Central

    Witzel, Katja; Hanschen, Franziska S.; Schreiner, Monika; Krumbein, Angelika; Ruppel, Silke; Grosch, Rita

    2013-01-01

    The soil-borne fungal pathogen Verticillium longisporum is able to penetrate the root of a number of plant species and spread systemically via the xylem. Fumigation of Verticillium contaminated soil with Brassica green manure is used as an environmentally friendly method for crop protection. Here we present a study focused on the potential role of glucosinolates and their breakdown products of the model plant Arabidopsis thaliana in suppressing growth of V. longisporum. For this purpose we analysed the glucosinolate composition of the leaves and roots of a set of 19 key accessions of A. thaliana. The effect of volatile glucosinolate hydrolysis products on the in vitro growth of the pathogen was tested by exposing the fungus to hydrated lyophilized plant tissue. Volatiles released from leaf tissue were more effective than from root tissue in suppressing mycelial growth of V. longisporum. The accessions varied in their efficacy, with the most effective suppressing mycelial growth by 90%. An analysis of glucosinolate profiles and their enzymatic degradation products revealed a correlation between fungal growth inhibition and the concentration of alkenyl glucosinolates, particularly 2-propenyl (2Prop) glucosinolate, respectively its hydrolysis products. Exposure of the fungus to purified 2Prop glucosinolate revealed that its suppressive activity was correlated with its concentration. Spiking of 2Prop glucosinolate to leaf material of one of the least effective A. thaliana accessions led to fungal growth suppression. It is suggested that much of the inhibitory effect observed for the tested accessions can be explained by the accumulation of 2Prop glucosinolate. PMID:24039726

  13. Arsenic uptake and speciation in Arabidopsis thaliana under hydroponic conditions.

    PubMed

    Park, Jin Hee; Han, Young-Soo; Seong, Hye Jin; Ahn, Joo Sung; Nam, In-Hyun

    2016-07-01

    Arsenic (As) uptake and species in Arabidopsis thaliana were evaluated under hydroponic conditions. Plant nutrient solutions were treated with arsenite [As(III)] or arsenate [As(V)], and aqueous As speciation was conducted using a solid phase extraction (SPE) cartridge. Arabidopsis reduced As(V) to As(III) in the nutrient solution, possibly due to root exudates such as organic acids or the efflux of As(III) from plant roots after in vivo reduction of As(V) to As(III). Arsenic uptake by Arabidopsis was associated with increased levels of Ca and Fe, and decreased levels of K in plant tissues. Arsenic in Arabidopsis mainly occurred as As(III), which was coordinated with oxygen and sulfur based on XANES and EXAFS results. The existence of As(III)O and As(III)S in EXAFS indicates partial biotransformation of As(III)O to a sulfur-coordinated form because of limited amount of glutathione in plants. Further understanding the mechanism of As biotransformation in Arabidopsis may help to develop measures that can mitigate As toxicity via genetic engineering. PMID:27058920

  14. Photomorphogenesis in Arabidopsis thaliana (L.) Heynh

    PubMed Central

    Brown, J. A. M.; Klein, W. H.

    1971-01-01

    Arabidopsis seeds were germinated on sterile mineral agar supplemented with 1% glucose and cultured under continuous light regimes. With 4-hour incandescent plus 20-hour monochromatic illumination in the region from 400 to 485 nanometers there was effective floral induction at an intensity of 100 microwatts per square centimeter. Exclusion of far red wave lengths from the 4-hour incandescent period sharply reduced the effectiveness of subsequent monochromatic blue light in promoting floral induction. Delayed floral induction occurred under continuous incandescent light lacking far red and was attributable to the blue wave lengths. Continuous 485 nanometer (100 microwatts per square centimeter) exposure without any white light treatment during the postgermination growth period was ineffective in floral induction and meristem development. Light at 730 nanometers under the same conditions was partially effective, whereas energy between 500 and 700 nanometers was completely ineffective. When continuous monochromatic light at a 3-fold higher energy level was administered, all photomorphogenic responses were accomplished with 485 nanometer light, including germination and 100% floral induction without any white light treatment at any time during the experiment. Almost equal quantum effectiveness was calculated when equivalent quantum flux densities in the region from 710 to 740 nanometers or at 485 nanometers were used. It is postulated that floral induction in Arabidopsis may be the result of a continuous excitation of a stable form of far red-absorbing phytochrome localized in or on a membrane, and that excitation can be either by direct absorption of energy by far red-absorbing phytochrome or by transfer from an accessory pigment. Images PMID:16657629

  15. Light responses in Photoperiodism in Arabidopsis thaliana

    SciTech Connect

    Anthony R. Cashmore

    2006-08-01

    ADO1: An Arabidopsis blue light photoreceptor We have reported the characterization of an Arabidopsis gene encoding the ADAGIO 1 (ADO1) protein (Jarillo et al., 2001a). ADO1 contains a LOV domain, similar to WHITE COLLAR 1 (WC1), a photoreceptor for entrainment of Neurospora circadian rhythms (Froehlich et al., 2002), as well as PHOT1 and PHOT2, the blue light photoreceptors for phototropism (Briggs et al., 2001; Christie et al., 1998; Jarillo et al., 2001b; Kinoshita et al., 2001). Loss of function ado1 mutants show an unusually long periodicity for their free running circadian rhythm (Jarillo et al., 2001a). This observation holds for plants grown under white light as well as blue light and surprisingly, plants grown under red light also show altered circadian properties. The similarity of the LOV domain of ADO1 to those of PHOT1, PHOT2 and WC1 (known flavoprotein photoreceptors) as well as the genetic and molecular properties of ADO1, indicate that ADO1 is likely a new class of blue light photoreceptor. Indeed, the LOV domain of the related FKF1/ADO3 has been shown to bind FMN, and exhibit the in vitro photochemistry characteristic of PHOT1 (Imaizumi et al., 2003). Furthermore, ZTL/ADO1 has been shown to participate in the circadian and proteasome mediated degradation of the Arabidopsis clock protein, TOC1 (Mas et al., 2003). We also showed that the ado1 mutation selectively confers hypersensitivity to red light — when grown under red light (but not blue light) the ado1 mutant possesses an unusually short hypocotyl. This red light hypersensivity is even more severe in a triple ado1 ado2 ado3 mutant — ADO2 and ADO3 being the two other members of this ADAGIO gene family. This finding of a mutant phenotype under red light is somewhat unexpected for a protein thought to function as a photoreceptor for blue light. We have pursued our studies of ADO1 by preparing a mutant gene for which we have altered the codon for the cysteine residue conserved in all LOV

  16. Involvement of NRAMP1 from Arabidopsis thaliana in iron transport.

    PubMed Central

    Curie, C; Alonso, J M; Le Jean, M; Ecker, J R; Briat, J F

    2000-01-01

    Nramp genes code for a widely distributed class of proteins involved in a variety of processes, ranging from the control of susceptibility to bacterial infection in mammalian cells and taste behaviour in Drosophila to manganese uptake in yeast. Some of the NRAMP proteins in mammals and in yeast are capable of transporting metal ions, including iron. In plants, iron transport was shown to require a reduction/Fe(II) transport system. In Arabidopsis thaliana this process involves the IRT1 and Fro2 genes. Here we report the sequence of five NRAMP proteins from A. thaliana. Sequence comparison suggests that there are two classes of NRAMP proteins in plants: A. thaliana (At) NRAMP1 and Oriza sativa (Os) NRAMP1 and 3 (two rice isologues) represent one class, and AtNRAMP2-5 and OsNRAMP2 the other. AtNramp1 and OsNramp1 are able to complement the fet3fet4 yeast mutant defective both in low- and high-affinity iron transports, whereas AtNramp2 and OsNramp2 fail to do so. In addition, AtNramp1 transcript, but not AtNramp2 transcript, accumulates in response to iron deficiency in roots but not in leaves. Finally, overexpression of AtNramp1 in transgenic A. thaliana plants leads to an increase in plant resistance to toxic iron concentration. Taken together, these results demonstrate that AtNramp1 participates in the control of iron homoeostasis in plants. PMID:10769179

  17. Involvement of NRAMP1 from Arabidopsis thaliana in iron transport.

    PubMed

    Curie, C; Alonso, J M; Le Jean, M; Ecker, J R; Briat, J F

    2000-05-01

    Nramp genes code for a widely distributed class of proteins involved in a variety of processes, ranging from the control of susceptibility to bacterial infection in mammalian cells and taste behaviour in Drosophila to manganese uptake in yeast. Some of the NRAMP proteins in mammals and in yeast are capable of transporting metal ions, including iron. In plants, iron transport was shown to require a reduction/Fe(II) transport system. In Arabidopsis thaliana this process involves the IRT1 and Fro2 genes. Here we report the sequence of five NRAMP proteins from A. thaliana. Sequence comparison suggests that there are two classes of NRAMP proteins in plants: A. thaliana (At) NRAMP1 and Oriza sativa (Os) NRAMP1 and 3 (two rice isologues) represent one class, and AtNRAMP2-5 and OsNRAMP2 the other. AtNramp1 and OsNramp1 are able to complement the fet3fet4 yeast mutant defective both in low- and high-affinity iron transports, whereas AtNramp2 and OsNramp2 fail to do so. In addition, AtNramp1 transcript, but not AtNramp2 transcript, accumulates in response to iron deficiency in roots but not in leaves. Finally, overexpression of AtNramp1 in transgenic A. thaliana plants leads to an increase in plant resistance to toxic iron concentration. Taken together, these results demonstrate that AtNramp1 participates in the control of iron homoeostasis in plants. PMID:10769179

  18. Ligand migration in nonsymbiotic hemoglobin AHb1 from Arabidopsis thaliana.

    PubMed

    Abbruzzetti, Stefania; Grandi, Elena; Bruno, Stefano; Faggiano, Serena; Spyrakis, Francesca; Mozzarelli, Andrea; Cacciatori, Elena; Dominici, Paola; Viappiani, Cristiano

    2007-11-01

    AHb1 is a hexacoordinated type 1 nonsymbiotic hemoglobin recently discovered in Arabidopsis thaliana. To gain insight into the ligand migration inside the protein, we studied the CO rebinding kinetics of AHb1 encapsulated in silica gels, in the presence of glycerol. The CO rebinding kinetics after nanosecond laser flash photolysis exhibits complex ligand migration patterns, consistent with the existence of discrete docking sites in which ligands can temporarily be stored before rebinding to the heme at different times. This finding may be of relevance to the physiological NO dioxygenase activity of this protein, which requires sequential binding of two substrates, NO and O2, to the heme. PMID:17924689

  19. A Chemical Genetic Screening Procedure for Arabidopsis thaliana Seedlings

    PubMed Central

    Bjornson, Marta; Song, Xingshun; Dandekar, Abhaya; Franz, Annaliese; Drakakaki, Georgia; Dehesh, Katayoon

    2016-01-01

    Unbiased screening approaches are powerful tools enabling identification of novel players in biological processes. Chemical genetic screening refers to the technique of using a reporter response, such as expression of luciferase driven by a promoter of interest, to discover small molecules that affect a given process when applied to plants. These chemicals then act as tools for identification of regulatory components that could not otherwise be detected by forward genetic screens due to gene family redundancy or mutant lethality. This protocol describes a chemical genetic screen using Arabidopsis thaliana seedlings, which has led to recognition of novel players in the plant general stress response.

  20. Microgravity effects on Arabidopsis thaliana energy pool

    NASA Astrophysics Data System (ADS)

    Dobrota, C.; Piso, M. I.; Banciu, H.; Keul, A.

    The flexibility of plant bioenergetics helps plants to acclimate to environmental stresses Our work is focused on standard free energy changes for PPi and ATP hydrolysis in order to assess the relative importance of PPi versus ATP as an energy donor in the plant cytosol of Arabidopsis plants exposed to microgravity The results indicated that PPi would be particularly favored as a phosphoryl donor relative to ATP under cytosolic conditions known to accompany stresses Recent researches showed that besides its functions inside the cell ATP may be released to the extracellular milieu where it functions as the primary signaling molecule of a diverse range of physiological processes It seems that extracellular ATP is essential for maintaining plant cell viability We intend to study how the production and the release of ATP is influenced by the microgravity References begin enumerate item Chivasaa S Bongani K Ndimbab W Simonc J Lindseyc K and Slabasc A 2005 Extracellular ATP Functions as an Endogenous External Metabolite Regulating Plant Cell Viability The Plant Cell 17 3019-3034 item Palma D A Blumwald E and Plaxton W C 2000 Upregulation of vacuolar H -translocating pyrophosphatase by phosphate starvation of Brassica napus rapeseed suspension cell cultures FEBS Letters 486 155-158 item Plaxton W C 2004 Plant response to stress Biochemical adaptations to phosphate deficiency In R Goodman ed Encyclopedia of Plant and Crop Science Marcel Dekker Inc N Y end enumerate

  1. Genetic analysis of photoreceptor action pathways in Arabidopsis thaliana

    SciTech Connect

    Not Available

    1991-01-01

    The specific strategies and long-term goals of this proposal remain intact relative to the original proposal. We continue to isolate and characterize photomorphogenic mutants of Arabidopsis thaliana. The molecular and biochemical characterization of one of these mutants, det1, has led to one publication of original data and to one Society for Experimental Biology Symposium paper (see below). The phenotype of a second mutant, det2, has also been studied during this funding period. In addition, we have continued work on a general strategy to isolate mutations in trans-acting regulatory factors that mediate light-regulated gene expression, and have identified several potentially interesting regulatory mutants. In the third funding period, we will concentrate on the genetical, biochemical, and molecular characterization of these new mutants. Construction of double mutants between the new mutants and the previously characterized morphological mutants should allow us to construct a pathway for light-regulated seedling development in Arabidopsis.

  2. A reference map of the Arabidopsis thaliana mature pollen proteome

    SciTech Connect

    Noir, Sandra; Braeutigam, Anne; Colby, Thomas; Schmidt, Juergen; Panstruga, Ralph . E-mail: panstrug@mpiz-koeln.mpg.de

    2005-12-02

    The male gametophyte (or pollen) plays an obligatory role during sexual reproduction of higher plants. The extremely reduced complexity of this organ renders pollen a valuable experimental system for studying fundamental aspects of plant biology such as cell fate determination, cell-cell interactions, cell polarity, and tip-growth. Here, we present the first reference map of the mature pollen proteome of the dicotyledonous model plant species, Arabidopsis thaliana. Based on two-dimensional gel electrophoresis, matrix-assisted laser desorption/ionization time-of-flight, and electrospray quadrupole time-of-flight mass spectrometry, we reproducibly identified 121 different proteins in 145 individual spots. The presence, subcellular localization, and functional classification of the identified proteins are discussed in relation to the pollen transcriptome and the full protein complement encoded by the nuclear Arabidopsis genome.

  3. Genetic control of polar cell expansion in Arabidopsis thaliana

    SciTech Connect

    Schiefelbein, J.; Ford, S. ); Somerville, C. )

    1990-05-01

    Certain plant cells, like root hairs and pollen tubes, exhibit polar cell growth, with expansion limited to the tip of the growing cell. In order to understand the mechanisms regulating polar cell expansion, we are studying the process of root hair elongation in Arabidopsis thaliana. By visually screening roots from 12,000 mutagenized Arabidopsis seedlings on Petri dishes, more than 40 root hair mutants have been identified. We have focused our attention on mutants that possess nuclear recessive mutations in three genes (RHD2, RHD3, and RDH4) that appear to be involved in controlling polar cell growth in root hairs. We are currently using cellular, genetic, and molecular approaches to understand these genes' normal roles in root hair elongation.

  4. Quantitative trait loci for inflorescence development in Arabidopsis thaliana.

    PubMed Central

    Ungerer, Mark C; Halldorsdottir, Solveig S; Modliszewski, Jennifer L; Mackay, Trudy F C; Purugganan, Michael D

    2002-01-01

    Variation in inflorescence development patterns is a central factor in the evolutionary ecology of plants. The genetic architectures of 13 traits associated with inflorescence developmental timing, architecture, rosette morphology, and fitness were investigated in Arabidopsis thaliana, a model plant system. There is substantial naturally occurring genetic variation for inflorescence development traits, with broad sense heritabilities computed from 21 Arabidopsis ecotypes ranging from 0.134 to 0.772. Genetic correlations are significant for most (64/78) pairs of traits, suggesting either pleiotropy or tight linkage among loci. Quantitative trait locus (QTL) mapping indicates 47 and 63 QTL for inflorescence developmental traits in Ler x Col and Cvi x Ler recombinant inbred mapping populations, respectively. Several QTL associated with different developmental traits map to the same Arabidopsis chromosomal regions, in agreement with the strong genetic correlations observed. Epistasis among QTL was observed only in the Cvi x Ler population, and only between regions on chromosomes 1 and 5. Examination of the completed Arabidopsis genome sequence in three QTL regions revealed between 375 and 783 genes per region. Previously identified flowering time, inflorescence architecture, floral meristem identity, and hormone signaling genes represent some of the many candidate genes in these regions. PMID:11901129

  5. Chromosomal rearrangement in autotetraploid plants of Arabidopsis thaliana.

    PubMed

    Weiss, H; Maluszynska, J

    2000-01-01

    Recent development of cytogenetic techniques has facilitated significant progress in Arabidopsis thaliana karyotype studies. Double-target FISH with rRNA genes provides makers that allow individual chromosome in the genome to be distinguished. Those studies have revealed that the number and position of rDNA loci is ecotype-specific. Arabidopsis is believed to be a true diploid (x = 5) with numerous ecotypes (accessions) and only a very few natural polyploid populations reported. Few studies were undertaken to induce polyploidy in Arabidopsis, however none of those gave the cytogenetic characteristics of polyploid plants. Our analysis of chromosome pairing of colchicine-induced autotetraploid Arabidopsis (Wilna ecotype) revealed preferential bivalent pairing in PMCs (pollen mother cells). In order to attempt to explain this phenomenon, first of all more detailed cytogenetic studies of autopolyploid plants have been undertaken. The localization of 45S and 5S rDNA loci in the diploid and autotetraploid plants revealed that Wilna ecotypes belongs to the group of Arabidopsis accessions with only two 5S rDNA loci present in a genome. Furthermore, the rearrangement of 45S rDNA locus in autopolyploid, when compared to the diploid plants of the same ecotype, was revealed. These results are interesting also in the context of the recently emphasised role of polyploidy in plant evolution and speciation. Arabidopsis, despite having small chromosomes, is a good system to study chromosome behaviour in relation to diploidization of autopolyploids and to evaluate the degree of chromosomal rearrangements during this process. PMID:11433970

  6. An Arabidopsis thaliana methyltransferase Capable of Methylating Farnesoic Acid

    SciTech Connect

    Yang,Y.; Yuan, J.; Ross, J.; Noel, J.; Pichersky, E.

    2006-01-01

    We previously reported the identification of a new family of plant methyltransferases (MTs), named the SABATH family, that use S-adenosyl-l-methionine (SAM) to methylate a carboxyl moiety or a nitrogen-containing functional group on a diverse array of plant compounds. The Arabidopsis genome alone contains 24 distinct SABATH genes. To identify the catalytic specificities of members of this protein family in Arabidopsis, we screened recombinantly expressed and purified enzymes with a large number of potential substrates. Here, we report that the Arabidopsis thaliana gene At3g44860 encodes a protein with high catalytic specificity towards farnesoic acid (FA). Under steady-state conditions, this farnesoic acid carboxyl methyltransferase (FAMT) exhibits K{sub M} values of 41 and 71 {mu}M for FA and SAM, respectively. A three-dimensional model of FAMT constructed based upon similarity to the experimentally determined structure of Clarkia breweri salicylic acid methyltransferase (SAMT) suggests a reasonable model for FA recognition in the FAMT active site. In plants, the mRNA levels of At3g44860 increase in response to the exogenous addition of several compounds previously shown to induce plant defense responses at the transcriptional level. Although methyl farnesoate (MeFA) has not yet been detected in Arabidopsis, the presence of a FA-specific carboxyl methyltransferase in Arabidopsis capable of producing MeFA, an insect juvenile hormone made by some plants as a presumed defense against insect herbivory, suggests that MeFA or chemically similar compounds are likely to serve as new specialized metabolites in Arabidopsis.

  7. Spatial dissection of the Arabidopsis thaliana transcriptional response to downy mildew using Fluorescence Activated Cell Sorting

    PubMed Central

    Coker, Timothy L. R.; Cevik, Volkan; Beynon, Jim L.; Gifford, Miriam L.

    2015-01-01

    Changes in gene expression form a crucial part of the plant response to infection. In the last decade, whole-leaf expression profiling has played a valuable role in identifying genes and processes that contribute to the interactions between the model plant Arabidopsis thaliana and a diverse range of pathogens. However, with some pathogens such as downy mildew caused by the biotrophic oomycete pathogen Hyaloperonospora arabidopsidis (Hpa), whole-leaf profiling may fail to capture the complete Arabidopsis response encompassing responses of non-infected as well as infected cells within the leaf. Highly localized expression changes that occur in infected cells may be diluted by the comparative abundance of non-infected cells. Furthermore, local and systemic Hpa responses of a differing nature may become conflated. To address this we applied the technique of Fluorescence Activated Cell Sorting (FACS), typically used for analyzing plant abiotic responses, to the study of plant-pathogen interactions. We isolated haustoriated (Hpa-proximal) and non-haustoriated (Hpa-distal) cells from infected seedling samples using FACS, and measured global gene expression. When compared with an uninfected control, 278 transcripts were identified as significantly differentially expressed, the vast majority of which were differentially expressed specifically in Hpa-proximal cells. By comparing our data to previous, whole organ studies, we discovered many highly locally regulated genes that can be implicated as novel in the Hpa response, and that were uncovered for the first time using our sensitive FACS technique. PMID:26217372

  8. Branched-Chain Amino Acid Metabolism in Arabidopsis thaliana

    PubMed Central

    Binder, Stefan

    2010-01-01

    Valine, leucine and isoleucine form the small group of branched-chain amino acids (BCAAs) classified by their small branched hydrocarbon residues. Unlike animals, plants are able to de novo synthesize these amino acids from pyruvate, 2-oxobutanoate and acetyl-CoA. In plants, biosynthesis follows the typical reaction pathways established for the formation of these amino acids in microorganisms. Val and Ile are synthesized in two parallel pathways using a single set of enzymes. The pathway to Leu branches of from the final intermediate of Val biosynthesis. The formation of this amino acid requires a three-step pathway generating a 2-oxoacid elongated by a methylene group. In Arabidopsis thaliana and other Brassicaceae, a homologous three-step pathway is also involved in Met chain elongation required for the biosynthesis of aliphatic glucosinolates, an important class of specialized metabolites in Brassicaceae. This is a prime example for the evolutionary relationship of pathways from primary and specialized metabolism. Similar to animals, plants also have the ability to degrade BCAAs. The importance of BCAA turnover has long been unclear, but now it seems apparent that the breakdown process might by relevant under certain environmental conditions. In this review, I summarize the current knowledge about BCAA metabolism, its regulation and its particular features in Arabidopsis thaliana. PMID:22303262

  9. Indole Glucosinolate Biosynthesis Limits Phenylpropanoid Accumulation in Arabidopsis thaliana

    PubMed Central

    2015-01-01

    Plants produce an array of metabolites (including lignin monomers and soluble UV-protective metabolites) from phenylalanine through the phenylpropanoid biosynthetic pathway. A subset of plants, including many related to Arabidopsis thaliana, synthesizes glucosinolates, nitrogen- and sulfur-containing secondary metabolites that serve as components of a plant defense system that deters herbivores and pathogens. Here, we report that the Arabidopsis thaliana reduced epidermal fluorescence5 (ref5-1) mutant, identified in a screen for plants with defects in soluble phenylpropanoid accumulation, has a missense mutation in CYP83B1 and displays defects in glucosinolate biosynthesis and in phenylpropanoid accumulation. CYP79B2 and CYP79B3 are responsible for the production of the CYP83B1 substrate indole-3-acetaldoxime (IAOx), and we found that the phenylpropanoid content of cyp79b2 cyp79b3 and ref5-1 cyp79b2 cyp79b3 plants is increased compared with the wild type. These data suggest that levels of IAOx or a subsequent metabolite negatively influence phenylpropanoid accumulation in ref5 and more importantly that this crosstalk is relevant in the wild type. Additional biochemical and genetic evidence indicates that this inhibition impacts the early steps of the phenylpropanoid biosynthetic pathway and restoration of phenylpropanoid accumulation in a ref5-1 med5a/b triple mutant suggests that the function of the Mediator complex is required for the crosstalk. PMID:25944103

  10. Aneuploidy and Genetic Variation in the Arabidopsis thaliana Triploid Response

    PubMed Central

    Henry, Isabelle M.; Dilkes, Brian P.; Young, Kim; Watson, Brian; Wu, Helen; Comai, Luca

    2005-01-01

    Polyploidy, the inheritance of more than two genome copies per cell, has played a major role in the evolution of higher plants. Little is known about the transition from diploidy to polyploidy but in some species, triploids are thought to function as intermediates in this transition. In contrast, in other species triploidy is viewed as a block. We investigated the responses of Arabidopsis thaliana to triploidy. The role of genetic variability was tested by comparing triploids generated from crosses between Col-0, a diploid, and either a natural autotetraploid (Wa-1) or an induced tetraploid of Col-0. In this study, we demonstrate that triploids of A. thaliana are fertile, producing a swarm of different aneuploids. Propagation of the progeny of a triploid for a few generations resulted in diploid and tetraploid cohorts. This demonstrated that, in A. thaliana, triploids can readily form tetraploids and function as bridges between euploid types. Genetic analysis of recombinant inbred lines produced from a triploid identified a locus on chromosome I exhibiting allelic bias in the tetraploid lines but not in the diploid lines. Thus, genetic variation was subject to selection contingent on the final ploidy and possibly acting during the protracted aneuploid phase. PMID:15944363

  11. Genetic Architecture of Mitochondrial Editing in Arabidopsis thaliana

    PubMed Central

    Bentolila, Stéphane; Elliott, Leah E.; Hanson, Maureen R.

    2008-01-01

    We have analyzed the mitochondrial editing behavior of two Arabidopsis thaliana accessions, Landsberg erecta (Ler) and Columbia (Col). A survey of 362 C-to-U editing sites in 33 mitochondrial genes was conducted on RNA extracted from rosette leaves. We detected 67 new editing events in A. thaliana rosette leaves that had not been observed in a prior study of mitochondrial editing in suspension cultures. Furthermore, 37 of the 441 C-to-U editing events reported in A. thaliana suspension cultures were not observed in rosette leaves. Forty editing sites that are polymorphic in extent of editing were detected between Col and Ler. Silent editing sites, which do not change the encoded amino acid, were found in a large excess compared to nonsilent sites among the editing events that differed between accessions and between tissue types. Dominance relationships were assessed for 15 of the most polymorphic sites by evaluating the editing values of the reciprocal hybrids. Dominance is more common in nonsilent sites than in silent sites, while additivity was observed only in silent sites. A maternal effect was detected for 8 sites. QTL mapping with recombinant inbred lines detected 12 major QTL for 11 of the 13 editing traits analyzed, demonstrating that efficiency of editing of individual mitochondrial C targets is generally governed by a major factor. PMID:17565941

  12. Molecular genetics of root gravitropism and waving in Arabidopsis thaliana

    NASA Technical Reports Server (NTRS)

    Sedbrook, J.; Boonsirichai, K.; Chen, R.; Hilson, P.; Pearlman, R.; Rosen, E.; Rutherford, R.; Batiza, A.; Carroll, K.; Schulz, T.; Masson, P. H.

    1998-01-01

    When Arabidopsis thaliana seedlings grow embedded in an agar-based medium, their roots grow vertically downward. This reflects their ability to sense the gravity vector and to position their tip parallel to it (gravitropism). We have isolated a number of mutations affecting root gravitropism in Arabidopsis thaliana. One of these mutations, named arg1, affects root and hypocotyl gravitropism without promoting defects in starch content or in the ability of seedlings' organs to respond to plant hormones. The ARG1 gene was cloned and shown to code for a protein with a J domain at its amino terminus and a second sequence motif found in several cytoskeleton binding proteins. Mutations in the AGR1 locus promote a strong defect in root gravitropism. Some alleles also confer an increased root resistance to exogenous ethylene and an increased sensitivity to auxin. AGR1 was cloned and found to encode a putative transmembrane protein which might be involved in polar auxin transport, or in regulating the differential growth response to gravistimulation. When Arabidopsis seedlings grow on the surface of agar-based media tilted backward, their roots wave. That wavy pattern of root growth derives from a combined response to gravity, touch and other surface-derived stimuli. It is accompanied by a reversible rotation of the root tip about its axis. A number of mutations affect the presence or the shape of root waves on tilted agar-based surfaces. One of them, wvc1, promotes the formation of compressed root waves under these conditions. The physiological and molecular analyses of this mutant suggest that a tryptophan-derived molecule other than IAA might be an important regulator of the curvature responsible for root waving.

  13. Programming of Plant Leaf Senescence with Temporal and Inter-Organellar Coordination of Transcriptome in Arabidopsis.

    PubMed

    Woo, Hye Ryun; Koo, Hee Jung; Kim, Jeongsik; Jeong, Hyobin; Yang, Jin Ok; Lee, Il Hwan; Jun, Ji Hyung; Choi, Seung Hee; Park, Su Jin; Kang, Byeongsoo; Kim, You Wang; Phee, Bong-Kwan; Kim, Jin Hee; Seo, Chaehwa; Park, Charny; Kim, Sang Cheol; Park, Seongjin; Lee, Byungwook; Lee, Sanghyuk; Hwang, Daehee; Nam, Hong Gil; Lim, Pyung Ok

    2016-05-01

    Plant leaves, harvesting light energy and fixing CO2, are a major source of foods on the earth. Leaves undergo developmental and physiological shifts during their lifespan, ending with senescence and death. We characterized the key regulatory features of the leaf transcriptome during aging by analyzing total- and small-RNA transcriptomes throughout the lifespan of Arabidopsis (Arabidopsis thaliana) leaves at multidimensions, including age, RNA-type, and organelle. Intriguingly, senescing leaves showed more coordinated temporal changes in transcriptomes than growing leaves, with sophisticated regulatory networks comprising transcription factors and diverse small regulatory RNAs. The chloroplast transcriptome, but not the mitochondrial transcriptome, showed major changes during leaf aging, with a strongly shared expression pattern of nuclear transcripts encoding chloroplast-targeted proteins. Thus, unlike animal aging, leaf senescence proceeds with tight temporal and distinct interorganellar coordination of various transcriptomes that would be critical for the highly regulated degeneration and nutrient recycling contributing to plant fitness and productivity. PMID:26966169

  14. A glycolate dehydrogenase in the mitochondria of Arabidopsis thaliana.

    PubMed

    Bari, Rafijul; Kebeish, Rashad; Kalamajka, Rainer; Rademacher, Thomas; Peterhänsel, Christoph

    2004-03-01

    The fixation of molecular O2 by the oxygenase activity of Rubisco leads to the formation of phosphoglycolate in the chloroplast that is further metabolized in the process of photorespiration. The initial step of this pathway is the oxidation of glycolate to glyoxylate. Whereas in higher plants this reaction takes place in peroxisomes and is dependent on oxygen as a co-factor, most algae oxidize glycolate in the mitochondria using organic co-factors. The identification and characterization of a novel glycolate dehydrogenase in Arabidopsis thaliana is reported here. The enzyme is dependent on organic co-factors and resembles algal glycolate dehydrogenases in its enzymatic properties. Mutants of E. coli incapable of glycolate oxidation can be complemented by overexpression of the Arabidopsis open reading frame. The corresponding RNA accumulates preferentially in illuminated leaves, but was also found in other tissues investigated. A fusion of the N-terminal part of the Arabidopsis glycolate dehydrogenase to red fluorescent protein accumulates in mitochondria when overexpressed in the homologous system. Based on these results it is proposed that the basic photorespiratory system of algae is conserved in higher plants. PMID:14966218

  15. Building a hair: tip growth in Arabidopsis thaliana root hairs.

    PubMed Central

    Carol, Rachel J; Dolan, Liam

    2002-01-01

    The Arabidopsis thaliana root hair is used as a model for studying tip growth in plants. We review recent advances, made using physiological and genetic approaches, which give rise to different, yet compatible, current views of the establishment and maintenance of tip growth in epidermal cells. For example, an active calcium influx channel localized at the tip of Arabidopsis root hairs has been identified by patch-clamp measurements. Actin has been visualized in vivo in Arabidopsis root hairs by using a green-fluorescent-protein-talin reporter and shown to form a dense mesh in the apex of the growing tip. The kojak gene, which encodes a protein similar to the catalytic subunit of cellulose synthase, is needed in the first stages of hair growth. A role for LRX1, a leucine-rich repeat extensin, in determining the morphology of the cell wall of root hairs has been established using reverse genetics. The new information can be integrated into a general and more advanced view of how these specialized plant cells grow. PMID:12079677

  16. Burkholderia phytofirmans PsJN reduces impact of freezing temperatures on photosynthesis in Arabidopsis thaliana

    PubMed Central

    Su, Fan; Jacquard, Cédric; Villaume, Sandra; Michel, Jean; Rabenoelina, Fanja; Clément, Christophe; Barka, Essaid A.; Dhondt-Cordelier, Sandrine; Vaillant-Gaveau, Nathalie

    2015-01-01

    Several plant growth-promoting rhizobacteria (PGPR) are known to improve plant tolerance to multiple stresses, including low temperatures. However, mechanisms underlying this protection are still poorly understood. The aim of this study was to evaluate the role of the endophytic PGPR, Burkholderia phytofirmans strain PsJN (Bp PsJN), on Arabidopsis thaliana cold tolerance using photosynthesis parameters as physiological markers. Under standard conditions, our results indicated that Bp PsJN inoculation led to growth promotion of Arabidopsis plants without significant modification on photosynthesis parameters and chloroplast organization. However, bacterial colonization induced a cell wall strengthening in the mesophyll. Impact of inoculation modes (either on seeds or by soil irrigation) and their effects overnight at 0, -1, or -3°C, were investigated by following photosystem II (PSII) activity and gas exchanges. Following low temperatures stress, a decrease of photosynthesis parameters was observed. In addition, during three consecutive nights or days at -1°C, PSII activity was monitored. Pigment contents, RuBisCO protein abundance, expression of several genes including RbcS, RbcL, CBF1, CBF2, CBF3, ICE1, COR15a, and COR78 were evaluated at the end of exposure. To assess the impact of the bacteria on cell ultrastructure under low temperatures, microscopic observations were achieved. Results indicated that freezing treatment induced significant changes in PSII activity as early as the first cold day, whereas the same impact on PSII activity was observed only during the third cold night. The significant effects conferred by PsJN were differential accumulation of pigments, and reduced expression of RbcL and COR78. Microscopical observations showed an alteration/disorganization in A. thaliana leaf mesophyll cells independently of the freezing treatments. The presence of bacteria during the three successive nights or days did not significantly improved A. thaliana

  17. Burkholderia phytofirmans PsJN reduces impact of freezing temperatures on photosynthesis in Arabidopsis thaliana.

    PubMed

    Su, Fan; Jacquard, Cédric; Villaume, Sandra; Michel, Jean; Rabenoelina, Fanja; Clément, Christophe; Barka, Essaid A; Dhondt-Cordelier, Sandrine; Vaillant-Gaveau, Nathalie

    2015-01-01

    Several plant growth-promoting rhizobacteria (PGPR) are known to improve plant tolerance to multiple stresses, including low temperatures. However, mechanisms underlying this protection are still poorly understood. The aim of this study was to evaluate the role of the endophytic PGPR, Burkholderia phytofirmans strain PsJN (Bp PsJN), on Arabidopsis thaliana cold tolerance using photosynthesis parameters as physiological markers. Under standard conditions, our results indicated that Bp PsJN inoculation led to growth promotion of Arabidopsis plants without significant modification on photosynthesis parameters and chloroplast organization. However, bacterial colonization induced a cell wall strengthening in the mesophyll. Impact of inoculation modes (either on seeds or by soil irrigation) and their effects overnight at 0, -1, or -3°C, were investigated by following photosystem II (PSII) activity and gas exchanges. Following low temperatures stress, a decrease of photosynthesis parameters was observed. In addition, during three consecutive nights or days at -1°C, PSII activity was monitored. Pigment contents, RuBisCO protein abundance, expression of several genes including RbcS, RbcL, CBF1, CBF2, CBF3, ICE1, COR15a, and COR78 were evaluated at the end of exposure. To assess the impact of the bacteria on cell ultrastructure under low temperatures, microscopic observations were achieved. Results indicated that freezing treatment induced significant changes in PSII activity as early as the first cold day, whereas the same impact on PSII activity was observed only during the third cold night. The significant effects conferred by PsJN were differential accumulation of pigments, and reduced expression of RbcL and COR78. Microscopical observations showed an alteration/disorganization in A. thaliana leaf mesophyll cells independently of the freezing treatments. The presence of bacteria during the three successive nights or days did not significantly improved A. thaliana

  18. Biochemical and molecular analysis of a transmembrane protein kinase from Arabidopsis thaliana. Progress report, January 1993

    SciTech Connect

    Bleecker, A.B.

    1993-06-01

    We have isolated genomic and cDNA clones encoding a novel receptor-like protein kinase from the higher plant Arabidopsis thaliana. This kinase is being studied by combining biochemical, molecular, and genetic approaches. Domain-specific antibodies immunodecorate a polypeptide with a molecular mass of 120,000 daltons in extracts of Arabidopsis, where it has been found in all portions of the plant examined including root, stem, leaf, flower, and silique. Cytochemical analysis and initial studies using the kinase promoter with the GUS reporter gene system also indicate that the kinase is present throughout the plant. The kinase is glycosylated, like animal receptor kinases, and has been partially purified from Arabidopsis by using lectin columns. The kinase has been expressed in E coli, purified, and found to autophosphorylate on serine and threonine residues, but not on tyrosine residues. As such, it belongs to the small family of receptor-like kinases with serine/threonine specificity. Transgenic plants are now being produced that either overexpress or carry altered forms of the protein kinase gene. These experiments will help determine the natural role the kinase plays in a pathway of signal transduction.

  19. Biochemical and molecular analysis of a transmembrane protein kinase from Arabidopsis thaliana

    SciTech Connect

    Bleecker, A.B.

    1993-01-01

    We have isolated genomic and cDNA clones encoding a novel receptor-like protein kinase from the higher plant Arabidopsis thaliana. This kinase is being studied by combining biochemical, molecular, and genetic approaches. Domain-specific antibodies immunodecorate a polypeptide with a molecular mass of 120,000 daltons in extracts of Arabidopsis, where it has been found in all portions of the plant examined including root, stem, leaf, flower, and silique. Cytochemical analysis and initial studies using the kinase promoter with the GUS reporter gene system also indicate that the kinase is present throughout the plant. The kinase is glycosylated, like animal receptor kinases, and has been partially purified from Arabidopsis by using lectin columns. The kinase has been expressed in E coli, purified, and found to autophosphorylate on serine and threonine residues, but not on tyrosine residues. As such, it belongs to the small family of receptor-like kinases with serine/threonine specificity. Transgenic plants are now being produced that either overexpress or carry altered forms of the protein kinase gene. These experiments will help determine the natural role the kinase plays in a pathway of signal transduction.

  20. Elucidation of the beta-carotene hydroxylation pathway in Arabidopsis thaliana.

    PubMed

    Fiore, Alessia; Dall'osto, Luca; Fraser, Paul D; Bassi, Roberto; Giuliano, Giovanni

    2006-08-21

    The first dedicated step in plant xanthophyll biosynthesis is carotenoid hydroxylation. In Arabidopsis thaliana, this reaction is performed by both heme (LUT1 and LUT5) and non-heme (CHY1 and CHY2) hydroxylases. No mutant completely abolishing alpha- or beta-carotene hydroxylation has been described to date. We constructed double and triple mutant combinations in CHY1, CHY2, LUT1, LUT5 and LUT2 (lycopene epsilon-cyclase). In chy1chy2lut2, 80% of leaf carotenoids is represented by beta-carotene. In chy1chy2lut5, beta-carotene hydroxylation is completely abolished, while hydroxylation of the beta-ring of alpha-carotene is still observed. The data are consistent with a role of LUT5 in beta-ring hydroxylation, and with the existence of an additional hydroxylase, acting on the beta-ring of alpha-, but not beta-carotene. PMID:16890225

  1. Preparation of stroma, thylakoid membrane, and lumen fractions from Arabidopsis thaliana chloroplasts for proteomic analysis.

    PubMed

    Hall, Michael; Mishra, Yogesh; Schröder, Wolfgang P

    2011-01-01

    For many studies regarding important chloroplast processes such as oxygenic photosynthesis, fractionation of the total chloroplast proteome is a necessary first step. Here, we describe a method for isolating the stromal, the thylakoid membrane, and the thylakoid lumen subchloroplast fractions from Arabidopsis thaliana leaf material. All three fractions can be isolated sequentially from the same plant material in a single day preparation. The isolated fractions are suitable for various proteomic analyses such as simple mapping studies or for more complex experiments such as differential expression analysis using two-dimensional difference gel electrophoresis (2D-DIGE) or mass spectrometry (MS)-based techniques. Besides this, the obtained fractions can also be used for many other purposes such as immunological assays, enzymatic activity assays, and studies of protein complexes by native-polyacrylamide gel electrophoresis (native-PAGE). PMID:21863445

  2. Exogenous isoprene modulates gene expression in unstressed Arabidopsis thaliana plants.

    PubMed

    Harvey, Christopher M; Sharkey, Thomas D

    2016-06-01

    Isoprene is a well-studied volatile hemiterpene that protects plants from abiotic stress through mechanisms that are not fully understood. The antioxidant and membrane stabilizing potential of isoprene are the two most commonly invoked mechanisms. However, isoprene also affects phenylpropanoid metabolism, suggesting an additional role as a signalling molecule. In this study, microarray-based gene expression profiling reveals transcriptional reprogramming of Arabidopsis thaliana plants fumigated for 24 h with a physiologically relevant concentration of isoprene. Functional enrichment analysis of fumigated plants revealed enhanced heat- and light-stress-responsive processes in response to isoprene. Isoprene induced a network enriched in ERF and WRKY transcription factors, which may play a role in stress tolerance. The isoprene-induced up-regulation of phenylpropanoid biosynthetic genes was specifically confirmed using quantitative reverse transcription polymerase chain reaction. These results support a role for isoprene as a signalling molecule, in addition to its possible roles as an antioxidant and membrane thermoprotectant. PMID:26477606

  3. Mild ammonium stress increases chlorophyll content in Arabidopsis thaliana

    PubMed Central

    Sanchez-Zabala, Joseba; González-Murua, Carmen; Marino, Daniel

    2015-01-01

    Nitrate (NO3−) and ammonium (NH4+) are the main forms of nitrogen available in the soil for plants. Excessive NH4+ accumulation in tissues is toxic for plants and exclusive NH4+-based nutrition enhances this effect. Ammonium toxicity syndrome commonly includes growth impairment, ion imbalance and chlorosis among others. In this work, we observed high intraspecific variability in chlorophyll content in 47 Arabidopsis thaliana natural accessions grown under 1 mM NH4+ or 1 mM NO3− as N-source. Interestingly, chlorophyll content increased in every accession upon ammonium nutrition. Moreover, this increase was independent of ammonium tolerance capacity. Thus, chlorosis seems to be an exclusive effect of severe ammonium toxicity while mild ammonium stress induces chlorophyll accumulation. PMID:25853545

  4. Arabidopsis thaliana SEPALLATA3 protein prokaryotic expression and purification.

    PubMed

    He, Q; Fu, A Y; Zhang, G C; Li, T J; Zhang, J H

    2015-01-01

    SEPALLATA3 (SEP3) can be attributed to E class gene of the ABCE model of floral organ development. In order to reveal how SEP3 proteins form polymers, and the relationship between the polymers and their biological functions, the experiments of Arabidopsis thaliana AtSEP3 protein soluble expression in vitro were performed to construct a vector of prokaryotic expression, and investigate induced expression of recombinant proteins in Escherichia coli cells. The protein soluble expression was analyzed through the aspects of different protein domains, induction time, induction temperature, etc. Different structural domains and expression conditions were screened, and 0.1% IPTG inducing at 22 oC for 15 h was estimated as an optimal expression strategy. The nickel chelating resin was used to purify the protein in size exclusion chromatography (SEC) and the results indicated that AtSEP3 protein was present in the form of tetramer. PMID:26025404

  5. Kinetics for phototropic curvature by etiolated seedlings of Arabidopsis thaliana

    NASA Technical Reports Server (NTRS)

    Orbovic, V.; Poff, K. L.

    1991-01-01

    An infrared-imaging system has been used to study the influence of gravity on the kinetics of first positive phototropism. The development of phototropic curvature of etiolated seedlings of Arabidopsis thaliana was measured in the absence of visible radiation. Following a pulse of blue light, stationary seedlings curved to a maximum of approximately 16 degrees about 80 minutes after stimulation. The seedlings then curved upward again or straightened by about 6 degrees during the subsequent 100 minutes. Seedlings rotated on a clinostat reached a similar maximum curvature following photostimulation. These seedlings maintained that curvature for 30 to 40 minutes before subsequently straightening to the same extent as the stationary seedlings. It is concluded that straightening is not a consequence of gravitropism, although gravity has some effect on the phototropism kinetics.

  6. A phospholipid uptake system in the model plant Arabidopsis thaliana.

    PubMed

    Poulsen, Lisbeth R; López-Marqués, Rosa L; Pedas, Pai R; McDowell, Stephen C; Brown, Elizabeth; Kunze, Reinhard; Harper, Jeffrey F; Pomorski, Thomas G; Palmgren, Michael

    2015-01-01

    Plants use solar energy to produce lipids directly from inorganic elements and are not thought to require molecular systems for lipid uptake from the environment. Here we show that Arabidopsis thaliana Aminophospholipid ATPase10 (ALA10) is a P4-type ATPase flippase that internalizes exogenous phospholipids across the plasma membrane, after which they are rapidly metabolized. ALA10 expression and phospholipid uptake are high in the epidermal cells of the root tip and in guard cells, the latter of which regulate the size of stomatal apertures to modulate gas exchange. ALA10-knockout mutants exhibit reduced phospholipid uptake at the root tips and guard cells and are affected in growth and transpiration. The presence of a phospholipid uptake system in plants is surprising. Our results suggest that one possible physiological role of this system is to internalize lysophosphatidylcholine, a signalling lipid involved in root development and stomatal control. PMID:26212235

  7. Mutagenesis of Arabidopsis Thaliana by N+ Ion Implantation

    NASA Astrophysics Data System (ADS)

    Zhang, Genfa; Shi, Xiaoming; Nie, Yanli; Jiang, Shan; Zhou, Hongyu; Lu, Ting; Zhang, Jun

    2006-05-01

    Ion implantation, as a new biophysically mutagenic technique, has shown a great potential for crop breeding. By analyzing polymorphisms of genomic DNA through RAPD-based DNA analysis, we compared the frequency and efficiency of somatic and germ-line mutations of Arabidopsis thaliana treated with N+ ion implantation and γ-rays radiation. Our data support the following conclusions: (1) N+ ion implantation can induce a much wider spectrum of mutations than γ-rays radiation does; (2) Unlike the linear correlation between the doses and their effect in γ-rays radiation, the dose-effect correlation in N+ ion implantation is nonlinear; (3) Like γ-rays radiation, both somatic and germ-line mutations could be induced by N+ ion implantation; and (4) RAPD deletion patterns are usually seen in N+ ion implantation induced mutation.

  8. Growth Distribution during Phototropism of Arabidopsis thaliana Seedlings.

    PubMed Central

    Orbovic, V.; Poff, K. L.

    1993-01-01

    The elongation rates of two opposite sides of hypocotyls of Arabidopsis thaliana seedlings were measured during phototropism by using an infrared imaging system. In first positive phototropism, second positive phototropism, and red light-enhanced first positive phototropism, curvature toward the light source was the result of an increase in the rate of elongation of the shaded side and a decrease in the rate of elongation of the lighted side of the seedlings. The phase of straightening that followed maximum curvature resulted from a decrease in the elongation rate of the shaded side and an increase in the elongation rate of the lighted side. These data for the three types of blue light-induced phototropism tested in this study and for the phase of straightening are all clearly consistent with the growth rate changes predicted by the Cholodny-Went theory. PMID:12231922

  9. Architectural phenotypes in the transparent testa mutants of Arabidopsis thaliana

    PubMed Central

    Buer, Charles S.; Djordjevic, Michael A.

    2009-01-01

    Flavonoids are low molecular weight secondary plant metabolites with a myriad of functions. As flavonoids affect auxin transport (an important growth-controlling hormone) and are biologically active in eukaryotes, flavonoid mutants were expected to have undescribed architectural phenotypes. The Arabidopsis thaliana transparent testa (tt) mutants are compromised in the enzymatic steps or transcriptional regulators affecting flavonoid synthesis. tt mutant seedlings were grown on hard-slanted agar (a stress condition), under varying light conditions, and in soil to examine the resulting growth patterns. These tt mutants revealed a wide variety of architectural phenotypes in root and aerial tissues. Mutants with increased inflorescences, siliques, and lateral root density or reduced stature are traits that could affect plant yield or performance under certain environmental conditions. The regulatory genes affected in architectural traits may provide useful molecular targets for examination in other plants. PMID:19129166

  10. Arabidopsis thaliana is an asymptomatic host of Alfalfa mosaic virus.

    PubMed

    Balasubramaniam, Muthukumar; Ibrahim, Amr; Kim, Bong-Suk; Loesch-Fries, L Sue

    2006-11-01

    The susceptibility of Arabidopsis thaliana ecotypes to infection by Alfalfa mosaic virus (AMV) was evaluated. Thirty-nine ecotypes supported both local and systemic infection, 26 ecotypes supported only local infection, and three ecotypes could not be infected. No obvious symptoms characteristic of virus infection developed on the susceptible ecotypes under standard conditions of culture. Parameters of AMV infection were characterized in ecotype Col-0, which supported systemic infection and accumulated higher levels of AMV than the symptomatic host Nicotiana tabacum. The formation of infectious AMV particles in infected Col-0 was confirmed by infectivity assays on a hypersensitive host and by electron microscopy of purified virions. Replication and transcription of AMV was confirmed by de novo synthesis of AMV subgenomic RNA in Col-0 protoplasts transfected with AMV RNA or plasmids harboring AMV cDNAs. PMID:16875753

  11. DIRECT AND RESIDUAL EFFECTS OF CADMIUM ON THE GROWTH AND ELEMENTAL COMPOSITION OF 'ARABIDOPSIS THALIANA'

    EPA Science Inventory

    Experiments were conducted to determine the direct (first generation) and residual (second generation) phytotoxicity of a range of cadmium concentrations on Arabidopsis thaliana. Plants were grown under greenhouse conditions in double-container, vermiculite-hydroponic plot-cultur...

  12. Loss of the two major leaf isoforms of sucrose-phosphate synthase in Arabidopsis thaliana limits sucrose synthesis and nocturnal starch degradation but does not alter carbon partitioning during photosynthesis

    PubMed Central

    Volkert, Kathrin; Debast, Stefan; Voll, Lars M.; Voll, Hildegard; Schießl, Ingrid; Hofmann, Jörg; Schneider, Sabine; Börnke, Frederik

    2014-01-01

    Sucrose (Suc)-phosphate synthase (SPS) catalyses one of the rate-limiting steps in the synthesis of Suc in plants. The Arabidopsis genome contains four annotated SPS genes which can be grouped into three different families (SPSA1, SPSA2, SPSB, and SPSC). However, the functional significance of this multiplicity of SPS genes is as yet only poorly understood. All four SPS isoforms show enzymatic activity when expressed in yeast although there is variation in sensitivity towards allosteric effectors. Promoter–reporter gene analyses and quantitative real-time reverse transcription–PCR studies indicate that no two SPS genes have the same expression pattern and that AtSPSA1 and AtSPSC represent the major isoforms expressed in leaves. An spsa1 knock-out mutant showed a 44% decrease in leaf SPS activity and a slight increase in leaf starch content at the end of the light period as well as at the end of the dark period. The spsc null mutant displayed reduced Suc contents towards the end of the photoperiod and a concomitant 25% reduction in SPS activity. In contrast, an spsa1/spsc double mutant was strongly impaired in growth and accumulated high levels of starch. This increase in starch was probably not due to an increased partitioning of carbon into starch, but was rather caused by an impaired starch mobilization during the night. Suc export from excised petioles harvested from spsa1/spsc double mutant plants was significantly reduced under illumination as well as during the dark period. It is concluded that loss of the two major SPS isoforms in leaves limits Suc synthesis without grossly changing carbon partitioning in favour of starch during the light period but limits starch degradation during the dark period. PMID:24994761

  13. Molecular Genetics of Root Thigmoresponsiveness in Arabidopsis thaliana

    NASA Technical Reports Server (NTRS)

    Masson, Patrick H.

    2002-01-01

    The molecular mechanisms that allow plant roots to use gravity and touch as growth guides are investigated. We are using a molecular genetic strategy in Arabidopsis thaliana to study these processes. When Arabidopsis thaliana seedlings grow on tilted hard-agar surfaces, their roots develop a wavy pattern of growth which appears to derive from a succession of left-handed and right-handed circumnutation-like processes triggered by gravity and touch stimulation (Okada and Shimura, 1990; Rutherford et al., 1998; Rutherford and Masson, 1996). Interestingly, mutations that affect root waving on tilted hard-agar surfaces can be identified and characterized. Some of these mutations affect root gravitropism, while others appear to be responsible for the production of abnormal waves (no waves, compressed or square waves, coils) without affecting gravitropism. The specific objectives of this project were to functionally characterize two genes (WVD2 and WVD6) which are required for root waving on tilted agar surfaces, but not for root gravitropism. Specific objectives included a physiological and cytological analysis of the mutants, and molecular cloning and characterization of the corresponding genes. As summarized in this paper, we have reached these objectives. We have also identified and partially characterized other mutations that affect root skewing on hard-agar surfaces (sku5-1 and ago1), and have completed our work on the root-wave phenotype associated with mutations in genes of the tryptophan biosynthesis pathway (Lynn et al., 1999; Rutherford et al., 1998; Sedbrook et al., 2000, 2002). We briefly describe our progress on the cloning and characterization of WVD6, WVD2 and SKU5, and provide a list of papers (published, or in preparation) that derived from this grant. We also discuss the biological implications of our findings, with special emphasis on the analysis of WVD2.

  14. Exploring Arabidopsis thaliana Root Endophytes via Single-Cell Genomics

    SciTech Connect

    Lundberg, Derek; Woyke, Tanja; Tringe, Susannah; Dangl, Jeff

    2014-03-19

    Land plants grow in association with microbial communities both on their surfaces and inside the plant (endophytes). The relationships between microbes and their host can vary from pathogenic to mutualistic. Colonization of the endophyte compartment occurs in the presence of a sophisticated plant immune system, implying finely tuned discrimination of pathogens from mutualists and commensals. Despite the importance of the microbiome to the plant, relatively little is known about the specific interactions between plants and microbes, especially in the case of endophytes. The vast majority of microbes have not been grown in the lab, and thus one of the few ways of studying them is by examining their DNA. Although metagenomics is a powerful tool for examining microbial communities, its application to endophyte samples is technically difficult due to the presence of large amounts of host plant DNA in the sample. One method to address these difficulties is single-cell genomics where a single microbial cell is isolated from a sample, lysed, and its genome amplified by multiple displacement amplification (MDA) to produce enough DNA for genome sequencing. This produces a single-cell amplified genome (SAG). We have applied this technology to study the endophytic microbes in Arabidopsis thaliana roots. Extensive 16S gene profiling of the microbial communities in the roots of multiple inbred A. thaliana strains has identified 164 OTUs as being significantly enriched in all the root endophyte samples compared to their presence in bulk soil.

  15. Nuclear micro-probe analysis of Arabidopsis thaliana leaves

    NASA Astrophysics Data System (ADS)

    Ager, F. J.; Ynsa, M. D.; Domínguez-Solís, J. R.; López-Martín, M. C.; Gotor, C.; Romero, L. C.

    2003-09-01

    Phytoremediation is a cost-effective plant-based approach for remediation of soils and waters which takes advantage of the remarkable ability of some plants to concentrate elements and compounds from the environment and to metabolize various molecules in their tissues, such as toxic heavy metals and organic pollutants. Nowadays, phytoremediation technology is becoming of paramount importance when environmental decontamination is concerned, due to the emerging knowledge of its physiological and molecular mechanisms and the new biological and engineering strategies designed to optimize and improve it. In addition, the feasibility of using plants for environmental cleanup has been confirmed by many different trials around the world. Arabidopsis thaliana plants can be used for basic studies to improve the technology on phytoremediation. Making use of nuclear microscopy techniques, in this paper we study leaves of wild type and transgenic A. thaliana plants grown in a cadmium-rich environment under different conditions. Micro-PIXE, RBS and SEM analyses, performed on the scanning proton micro-probe at the CNA in Seville (Spain), prove that cadmium is preferentially sequestered in the central region of epidermal trichome and allow comparing the effects of genetic modifications.

  16. Positional distribution of transcription factor binding sites in Arabidopsis thaliana

    PubMed Central

    Yu, Chun-Ping; Lin, Jinn-Jy; Li, Wen-Hsiung

    2016-01-01

    Binding of a transcription factor (TF) to its DNA binding sites (TFBSs) is a critical step to initiate the transcription of its target genes. It is therefore interesting to know where the TFBSs of a gene are likely to locate in the promoter region. Here we studied the positional distribution of TFBSs in Arabidopsis thaliana, for which many known TFBSs are now available. We developed a method to identify the locations of TFBSs in the promoter sequences of genes in A. thaliana. We found that the distribution is nearly bell-shaped with a peak at 50 base pairs (bp) upstream of the transcription start site (TSS) and 86% of the TFBSs are in the region from −1,000 bp to +200 bp with respect to the TSS. Our distribution was supported by chromatin immunoprecipitation sequencing and microarray data and DNase I hypersensitive site sequencing data. When TF families were considered separately, differences in positional preference were observed between TF families. Our study of the positional distribution of TFBSs seems to be the first in a plant. PMID:27117388

  17. Iron acquisition from Fe-pyoverdine by Arabidopsis thaliana.

    PubMed

    Vansuyt, Gérard; Robin, Agnès; Briat, Jean-François; Curie, Catherine; Lemanceau, Philippe

    2007-04-01

    Taking into account the strong iron competition in the rhizosphere and the high affinity of pyoverdines for Fe(III), these molecules are expected to interfere with the iron nutrition of plants, as they do with rhizospheric microbes. The impact of Fe-pyoverdine on iron content of Arabidopsis thaliana was compared with that of Fe-EDTA. Iron chelated to pyoverdine was incorporated in a more efficient way than when chelated to EDTA, leading to increased plant growth of the wild type. A transgenic line of A. thaliana overexpressing ferritin showed a higher iron content than the wild type when supplemented with Fe-EDTA but a lower iron content when supplemented with Fe-pyoverdine despite its increased reductase activity, suggesting that this activity was not involved in the iron uptake from pyoverdine. A mutant knock-out iron transporter IRT1 showed lower iron and chlorophyll contents when supplemented with Fe-EDTA than the wild type but not when supplemented with Fe-pyoverdine, indicating that, in contrast to iron from EDTA, iron from pyoverdine was not incorporated through the IRT1 transporter. Altogether these data suggest that iron from Fe-pyoverdine was not incorporated in planta through the strategy I, which is based on reductase activity and IRT1 transporter. This is supported by the presence of pyoverdine in planta as shown by enzyme-linked immunosorbent assay and by tracing 15N of 15N-pyoverdine. PMID:17427814

  18. Allyl isothiocyanate affects the cell cycle of Arabidopsis thaliana

    PubMed Central

    Åsberg, Signe E.; Bones, Atle M.; Øverby, Anders

    2015-01-01

    Isothiocyanates (ITCs) are degradation products of glucosinolates present in members of the Brassicaceae family acting as herbivore repellents and antimicrobial compounds. Recent results indicate that allyl ITC (AITC) has a role in defense responses such as glutathione depletion, ROS generation and stomatal closure. In this study we show that exposure to non-lethal concentrations of AITC causes a shift in the cell cycle distribution of Arabidopsis thaliana leading to accumulation of cells in S-phases and a reduced number of cells in non-replicating phases. Furthermore, transcriptional analysis revealed an AITC-induced up-regulation of the gene encoding cyclin-dependent kinase A while several genes encoding mitotic proteins were down-regulated, suggesting an inhibition of mitotic processes. Interestingly, visualization of DNA synthesis indicated that exposure to AITC reduced the rate of DNA replication. Taken together, these results indicate that non-lethal concentrations of AITC induce cells of A. thaliana to enter the cell cycle and accumulate in S-phases, presumably as a part of a defensive response. Thus, this study suggests that AITC has several roles in plant defense and add evidence to the growing data supporting a multifunctional role of glucosinolates and their degradation products in plants. PMID:26042144

  19. Differentiation between MAMP Triggered Defenses in Arabidopsis thaliana

    PubMed Central

    Vetter, Madlen; Karasov, Talia L.; Bergelson, Joy

    2016-01-01

    A first line of defense against pathogen attack for both plants and animals involves the detection of microbe-associated molecular patterns (MAMPs), followed by the induction of a complex immune response. Plants, like animals, encode several receptors that recognize different MAMPs. While these receptors are thought to function largely redundantly, the physiological responses to different MAMPs can differ in detail. Responses to MAMP exposure evolve quantitatively in natural populations of Arabidopsis thaliana, perhaps in response to environment specific differences in microbial threat. Here, we sought to determine the extent to which the detection of two canonical MAMPs were evolving redundantly or distinctly within natural populations. Our results reveal negligible correlation in plant growth responses between the bacterial MAMPs EF-Tu and flagellin. Further investigation of the genetic bases of differences in seedling growth inhibition and validation of 11 candidate genes reveal substantial differences in the genetic loci that underlie variation in response to these two MAMPs. Our results indicate that natural variation in MAMP recognition is largely MAMP-specific, indicating an ability to differentially tailor responses to EF-Tu and flagellin in A. thaliana populations. PMID:27336582

  20. Phosphate transporters from the higher plant Arabidopsis thaliana.

    PubMed Central

    Muchhal, U S; Pardo, J M; Raghothama, K G

    1996-01-01

    Two cDNAs (AtPT1 and AtPT2) encoding plant phosphate transporters have been isolated from a library prepared with mRNA extracted from phosphate-starved Arabidopsis thaliana roots, The encoded polypeptides are 78% identical to each other and show high degree of amino acid sequence similarity with high-affinity phosphate transporters of Saccharomyces cerevisiae, Neurospora crassa, and the mycorrhizal fungus Glomus versiforme. The AtPT1 and AtPT2 polypeptides are integral membrane proteins predicted to contain 12 membrane-spanning domains separated into two groups of six by a large charged hydrophilic region. Upon expression, both AtPT1 and AtPT2 were able to complement the pho84 mutant phenotype of yeast strain NS219 lacking the high-affinity phosphate transport activity. AtPT1 and AtPT2 are representatives of two distinct, small gene families in A. thaliana. The transcripts of both genes are expressed in roots and are not detectable in leaves. The steady-state level of their mRNAs increases in response to phosphate starvation. Images Fig. 3 Fig. 4 Fig. 5 PMID:8927627

  1. Editing of plastid RNA in Arabidopsis thaliana ecotypes.

    PubMed

    Tillich, Michael; Funk, Helena T; Schmitz-Linneweber, Christian; Poltnigg, Peter; Sabater, Bartolomé; Martin, Mercedes; Maier, Rainer M

    2005-09-01

    Post-transcriptional maturation of plastid-encoded mRNAs from land plants includes editing by making cytidine to uridine alterations at highly specific positions; this usually restores codon identities for conserved amino acids that are important for the proper function of the affected proteins. In contrast to the rather constant number of editing sites their location varies greatly, even between closely related taxa. Here, we experimentally determined the specific pattern of editing sites (the editotype) of the plastid genome of Arabidopsis thaliana ecotype Columbia (Col-0). Based on phylogenetic analyses of plastid open reading frames, we identified 28 editing sites. Two editing events in the genes matK and ndhB seem to have evolved late during the evolution of flowering plants. Strikingly, they are embedded in almost identical sequence elements and seem to be phylogenetically co-processed. This suggests that the two sites are recognized by the same trans-factor, which could help to explain the hitherto enigmatic gain of editing sites in evolution. In order to trace variations in editotype at the subspecies level we examined two other A. thaliana accessions, Cape Verde Islands (Cvi-0) and Wassilewskija (Ws-2), for the Col-0 editing sites. Both Cvi-0 and Ws-2 possess and process the whole set of editing sites as determined in Col-0, but the consequences of RNA editing differ at one position between the ecotypes. PMID:16115067

  2. Modification of reproductive development in Arabidopsis thaliana under spaceflight conditions

    NASA Technical Reports Server (NTRS)

    Kuang, A.; Musgrave, M. E.; Matthews, S. W.

    1996-01-01

    Reproductive development in Arabidopsis thaliana (L.) Heynh. cv. Columbia plants was investigated under spaceflight conditions on shuttle mission STS-51. Plants launched just prior to initiation of the reproductive phase developed flowers and siliques during the 10-d flight. Approximately 500 flowers were produced in total by the 12 plants in both the ground control and spaceflight material, and there was no significant difference in the number of flowers in each size class. The flower buds and siliques of the spaceflight plants were not morphologically different from the ground controls. Pollen viability tests immediately post-flight using fluorescein diacetate indicated that about 35% of the pollen was viable in the spaceflight material. Light-microscopy observations on this material showed that the female gametophytes also had developed normally to maturity. However, siliques from the spaceflight plants contained empty, shrunken ovules, and no evidence of pollen transfer to stigmatic papillae was found by light microscopy immediately post-flight or by scanning electron microscopy on fixed material. Short stamen length and indehiscent anthers were observed in the spaceflight material, and a film-like substance inside the anther that connected to the tapetum appeared to restrict the release of pollen from the anthers. These observations indicate that given appropriate growing conditions, early reproductive development in A. thaliana can occur normally under spaceflight conditions. On STS-51, reproductive development aborted due to obstacles in pollination or fertilization.

  3. Differentiation between MAMP Triggered Defenses in Arabidopsis thaliana.

    PubMed

    Vetter, Madlen; Karasov, Talia L; Bergelson, Joy

    2016-06-01

    A first line of defense against pathogen attack for both plants and animals involves the detection of microbe-associated molecular patterns (MAMPs), followed by the induction of a complex immune response. Plants, like animals, encode several receptors that recognize different MAMPs. While these receptors are thought to function largely redundantly, the physiological responses to different MAMPs can differ in detail. Responses to MAMP exposure evolve quantitatively in natural populations of Arabidopsis thaliana, perhaps in response to environment specific differences in microbial threat. Here, we sought to determine the extent to which the detection of two canonical MAMPs were evolving redundantly or distinctly within natural populations. Our results reveal negligible correlation in plant growth responses between the bacterial MAMPs EF-Tu and flagellin. Further investigation of the genetic bases of differences in seedling growth inhibition and validation of 11 candidate genes reveal substantial differences in the genetic loci that underlie variation in response to these two MAMPs. Our results indicate that natural variation in MAMP recognition is largely MAMP-specific, indicating an ability to differentially tailor responses to EF-Tu and flagellin in A. thaliana populations. PMID:27336582

  4. Arabidopsis thaliana DNA gyrase is targeted to chloroplasts and mitochondria

    PubMed Central

    Wall, Melisa K.; Mitchenall, Lesley A.; Maxwell, Anthony

    2004-01-01

    DNA gyrase is the bacterial DNA topoisomerase (topo) that supercoils DNA by using the free energy of ATP hydrolysis. The enzyme, an A2B2 tetramer encoded by the gyrA and gyrB genes, catalyses topological changes in DNA during replication and transcription, and is the only topo that is able to introduce negative supercoils. Gyrase is essential in bacteria and apparently absent from eukaryotes and is, consequently, an important target for antibacterial agents (e.g., quinolones and coumarins). We have identified four putative gyrase genes in the model plant Arabidopsis thaliana; one gyrA and three gyrB homologues. DNA gyrase protein A (GyrA) has a dual translational initiation site targeting the mature protein to both chloroplasts and mitochondria, and there are individual targeting sequences for two of the DNA gyrase protein B (GyrB) homologues. N-terminal fusions of the organellar targeting sequences to GFPs support the hypothesis that one enzyme is targeted to the chloroplast and another to the mitochondrion, which correlates with supercoiling activity in isolated organelles. Treatment of seedlings and cultured cells with gyrase-specific drugs leads to growth inhibition. Knockout of A. thaliana gyrA is embryo-lethal whereas knockouts in the gyrB genes lead to seedling-lethal phenotypes or severely stunted growth and development. The A. thaliana genes have been cloned in Escherichia coli and found to complement gyrase temperature-sensitive strains. This report confirms the existence of DNA gyrase in eukaryotes and has important implications for drug targeting, organelle replication, and the evolution of topos in plants. PMID:15136745

  5. Targeted mutagenesis of Arabidopsis thaliana using engineered TAL effector nucleases.

    PubMed

    Christian, Michelle; Qi, Yiping; Zhang, Yong; Voytas, Daniel F

    2013-10-01

    Custom TAL effector nucleases (TALENs) are increasingly used as reagents to manipulate genomes in vivo. Here, we used TALENs to modify the genome of the model plant, Arabidopsis thaliana. We engineered seven TALENs targeting five Arabidopsis genes, namely ADH1, TT4, MAPKKK1, DSK2B, and NATA2. In pooled seedlings expressing the TALENs, we observed somatic mutagenesis frequencies ranging from 2-15% at the intended targets for all seven TALENs. Somatic mutagenesis frequencies as high as 41-73% were observed in individual transgenic plant lines expressing the TALENs. Additionally, a TALEN pair targeting a tandemly duplicated gene induced a 4.4-kb deletion in somatic cells. For the most active TALEN pairs, namely those targeting ADH1 and NATA2, we found that TALEN-induced mutations were transmitted to the next generation at frequencies of 1.5-12%. Our work demonstrates that TALENs are useful reagents for achieving targeted mutagenesis in this important plant model. PMID:23979944

  6. Determination of Arabidopsis thaliana telomere length by PCR.

    PubMed

    Vaquero-Sedas, María I; Vega-Palas, Miguel A

    2014-01-01

    In humans, telomere length studies have acquired great relevance because the length of telomeres has been related to natural processes like disease, aging and cancer. However, very little is known about the influence of telomere length on the biology of wild type plants. The length of plant telomeres has been usually studied by Terminal Restriction Fragment (TRF) analyses. This technique requires high amounts of tissue, including multiple cell types, which might be the reason why very little is known about the influence of telomere length on plant natural processes. In contrast, many of the human telomere length studies have focused on homogenous cell populations. Most of these studies have been performed by PCR, using telomeric degenerated primers, which allow the determination of telomere length from small amounts of human cells. Here, we have adapted the human PCR procedure to analyze the length of Arabidopsis thaliana telomeres. This PCR approach will facilitate the analysis of telomere length from low amounts of tissue. We have used it to determine that CG and non CG DNA methylation positively regulates Arabidopsis telomere length. PMID:24986269

  7. Determination of Arabidopsis thaliana telomere length by PCR

    PubMed Central

    Vaquero-Sedas, María I.; Vega-Palas, Miguel A.

    2014-01-01

    In humans, telomere length studies have acquired great relevance because the length of telomeres has been related to natural processes like disease, aging and cancer. However, very little is known about the influence of telomere length on the biology of wild type plants. The length of plant telomeres has been usually studied by Terminal Restriction Fragment (TRF) analyses. This technique requires high amounts of tissue, including multiple cell types, which might be the reason why very little is known about the influence of telomere length on plant natural processes. In contrast, many of the human telomere length studies have focused on homogenous cell populations. Most of these studies have been performed by PCR, using telomeric degenerated primers, which allow the determination of telomere length from small amounts of human cells. Here, we have adapted the human PCR procedure to analyze the length of Arabidopsis thaliana telomeres. This PCR approach will facilitate the analysis of telomere length from low amounts of tissue. We have used it to determine that CG and non CG DNA methylation positively regulates Arabidopsis telomere length. PMID:24986269

  8. The RNA-binding protein repertoire of Arabidopsis thaliana.

    PubMed

    Marondedze, Claudius; Thomas, Ludivine; Serrano, Natalia L; Lilley, Kathryn S; Gehring, Chris

    2016-01-01

    RNA-binding proteins (RBPs) have essential roles in determining the fate of RNA from synthesis to decay and have been studied on a protein-by-protein basis, or computationally based on a number of well-characterised RNA-binding domains. Recently, high-throughput methods enabled the capture of mammalian RNA-binding proteomes. To gain insight into the role of Arabidopsis thaliana RBPs at the systems level, we have employed interactome capture techniques using cells from different ecotypes grown in cultures and leaves. In vivo UV-crosslinking of RNA to RBPs, oligo(dT) capture and mass spectrometry yielded 1,145 different proteins including 550 RBPs that either belong to the functional category 'RNA-binding', have known RNA-binding domains or have orthologs identified in mammals, C. elegans, or S. cerevisiae in addition to 595 novel candidate RBPs. We noted specific subsets of RBPs in cultured cells and leaves and a comparison of Arabidopsis, mammalian, C. elegans, and S. cerevisiae RBPs reveals a common set of proteins with a role in intermediate metabolism, as well as distinct differences suggesting that RBPs are also species and tissue specific. This study provides a foundation for studies that will advance our understanding of the biological significance of RBPs in plant developmental and stimulus specific responses. PMID:27405932

  9. Genetic architecture of regulatory variation in Arabidopsis thaliana.

    PubMed

    Zhang, Xu; Cal, Andrew J; Borevitz, Justin O

    2011-05-01

    Studying the genetic regulation of expression variation is a key method to dissect complex phenotypic traits. To examine the genetic architecture of regulatory variation in Arabidopsis thaliana, we performed genome-wide association (GWA) mapping of gene expression in an F(1) hybrid diversity panel. At a genome-wide false discovery rate (FDR) of 0.2, an associated single nucleotide polymorphism (SNP) explains >38% of trait variation. In comparison with SNPs that are distant from the genes to which they were associated, locally associated SNPs are preferentially found in regions with extended linkage disequilibrium (LD) and have distinct population frequencies of the derived alleles (where Arabidopsis lyrata has the ancestral allele), suggesting that different selective forces are acting. Locally associated SNPs tend to have additive inheritance, whereas distantly associated SNPs are primarily dominant. In contrast to results from mapping of expression quantitative trait loci (eQTL) in linkage studies, we observe extensive allelic heterogeneity for local regulatory loci in our diversity panel. By association mapping of allele-specific expression (ASE), we detect a significant enrichment for cis-acting variation in local regulatory variation. In addition to gene expression variation, association mapping of splicing variation reveals both local and distant genetic regulation for intron and exon level traits. Finally, we identify candidate genes for 59 diverse phenotypic traits that were mapped to eQTL. PMID:21467266

  10. Arabidopsis thaliana root growth kinetics and lunisolar tidal acceleration.

    PubMed

    Fisahn, Joachim; Yazdanbakhsh, Nima; Klingele, Emile; Barlow, Peter

    2012-07-01

    • All living organisms on Earth are continually exposed to diurnal variations in the gravitational tidal force due to the Sun and Moon. • Elongation of primary roots of Arabidopsis thaliana seedlings maintained at a constant temperature was monitored for periods of up to 14 d using high temporal- and spatial-resolution video imaging. The time-course of the half-hourly elongation rates exhibited an oscillation which was maintained when the roots were placed in the free-running condition of continuous illumination. • Correlation between the root growth kinetics collected from seedlings initially raised under several light protocols but whose roots were subsequently in the free-running condition and the lunisolar tidal profiles enabled us to identify that the latter is the probable exogenous determinant of the rhythmic variation in root elongation rate. Similar observations and correlations using roots of Arabidopsis starch mutants suggest a central function of starch metabolism in the response to the lunisolar tide. The periodicity of the lunisolar tidal signal and the concomitant adjustments in root growth rate indicate that an exogenous timer exists for the modulation of root growth and development. • We propose that, in addition to the sensitivity to Earthly 1G gravity, which is inherent to all animals and plants, there is another type of responsiveness which is attuned to the natural diurnal variations of the lunisolar tidal force. PMID:22583121

  11. The RNA-binding protein repertoire of Arabidopsis thaliana

    PubMed Central

    Marondedze, Claudius; Thomas, Ludivine; Serrano, Natalia L.; Lilley, Kathryn S.; Gehring, Chris

    2016-01-01

    RNA-binding proteins (RBPs) have essential roles in determining the fate of RNA from synthesis to decay and have been studied on a protein-by-protein basis, or computationally based on a number of well-characterised RNA-binding domains. Recently, high-throughput methods enabled the capture of mammalian RNA-binding proteomes. To gain insight into the role of Arabidopsis thaliana RBPs at the systems level, we have employed interactome capture techniques using cells from different ecotypes grown in cultures and leaves. In vivo UV-crosslinking of RNA to RBPs, oligo(dT) capture and mass spectrometry yielded 1,145 different proteins including 550 RBPs that either belong to the functional category ‘RNA-binding’, have known RNA-binding domains or have orthologs identified in mammals, C. elegans, or S. cerevisiae in addition to 595 novel candidate RBPs. We noted specific subsets of RBPs in cultured cells and leaves and a comparison of Arabidopsis, mammalian, C. elegans, and S. cerevisiae RBPs reveals a common set of proteins with a role in intermediate metabolism, as well as distinct differences suggesting that RBPs are also species and tissue specific. This study provides a foundation for studies that will advance our understanding of the biological significance of RBPs in plant developmental and stimulus specific responses. PMID:27405932

  12. Antioxidative and proteolytic systems protect mitochondria from oxidative damage in S-deficient Arabidopsis thaliana.

    PubMed

    Ostaszewska-Bugajska, Monika; Rychter, Anna M; Juszczuk, Izabela M

    2015-08-15

    We examined the functioning of the antioxidative defense system in Arabidopsis thaliana under sulphur (S) deficiency with an emphasis on the role of mitochondria. In tissue extracts and in isolated mitochondria from S-deficient plants, the concentration of non-protein thiols declined but protein thiols did not change. Superoxide anion and hydrogen peroxide were accumulated in leaf blades and the generation of superoxide anion by isolated mitochondria was higher. Lower abundance of reduced (GSH) plus oxidized (GSSG) glutathione in the leaf and root tissues, and leaf mitochondria from S-deficient plants was accompanied by a decrease in the level of GSH and the changes in the GSH/GSSG ratios. In the chloroplasts, the total level of glutathione decreased. Lower levels of reduced (AsA) and oxidized (DHA) ascorbate were reflected in much higher ratios of AsA/DHA. Sulphur deficiency led to an increase in the activity of cytosolic, mitochondrial and chloroplastic antioxidative enzymes, peroxidases, catalases and superoxide dismutases. The protein carbonyl level was higher in the leaves of S-deficient plants and in the chloroplasts, while in the roots, leaf and root mitochondria it remained unchanged. Protease activity in leaf extracts of S-deficient plants was higher, but in root extracts it did not differ. The proteolytic system reflected subcellular specificity. In leaf and root mitochondria the protease activity was higher, whereas in the chloroplasts it did not change. We propose that the preferential incorporation of S to protein thiols and activation of antioxidative and proteolytic systems are likely important for the survival of S-deficient plants and that the mitochondria maintain redox homeostasis. PMID:26339750

  13. Crystallization and preliminary X-ray analysis of immunophilin-like FKBP42 from Arabidopsis thaliana

    SciTech Connect

    Eckhoff, Andreas; Granzin, Joachim; Kamphausen, Thilo; Büldt, Georg; Schulz, Burkhard; Weiergräber, Oliver H.

    2005-04-01

    The crystallization of FKBP42, a multi-domain member of the FK506-binding protein family, from the plant A. thaliana is reported. Two fragments of FKBP42 from Arabidopsis thaliana covering differing lengths of the molecule have been expressed, purified and crystallized. For each construct, crystals belonging to two different space groups were obtained and subjected to preliminary X-ray analysis.

  14. An autophosphorylation site database for leucine-rich repeat receptor-like kinases in Arabidopsis thaliana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We conducted a family-wide study to identify and characterize sites of autophosphorylation in 73 representative LRR RLKs of the 223 member LRR RLK family in Arabidopsis thaliana. His-tagged constructs of intact cytoplasmic domains (CDs) for 73 of 223 A. thaliana LRR RLKs were cloned into E. coli BL-...

  15. NAC Transcription Factor SPEEDY HYPONASTIC GROWTH Regulates Flooding-Induced Leaf Movement in Arabidopsis[W

    PubMed Central

    Rauf, Mamoona; Arif, Muhammad; Fisahn, Joachim; Xue, Gang-Ping; Balazadeh, Salma; Mueller-Roeber, Bernd

    2013-01-01

    In rosette plants, root flooding (waterlogging) triggers rapid upward (hyponastic) leaf movement representing an important architectural stress response that critically determines plant performance in natural habitats. The directional growth is based on localized longitudinal cell expansion at the lower (abaxial) side of the leaf petiole and involves the volatile phytohormone ethylene (ET). We report the existence of a transcriptional core unit underlying directional petiole growth in Arabidopsis thaliana, governed by the NAC transcription factor SPEEDY HYPONASTIC GROWTH (SHYG). Overexpression of SHYG in transgenic Arabidopsis thaliana enhances waterlogging-triggered hyponastic leaf movement and cell expansion in abaxial cells of the basal petiole region, while both responses are largely diminished in shyg knockout mutants. Expression of several EXPANSIN and XYLOGLUCAN ENDOTRANSGLYCOSYLASE/HYDROLASE genes encoding cell wall–loosening proteins was enhanced in SHYG overexpressors but lowered in shyg. We identified ACC OXIDASE5 (ACO5), encoding a key enzyme of ET biosynthesis, as a direct transcriptional output gene of SHYG and found a significantly reduced leaf movement in response to root flooding in aco5 T-DNA insertion mutants. Expression of SHYG in shoot tissue is triggered by root flooding and treatment with ET, constituting an intrinsic ET-SHYG-ACO5 activator loop for rapid petiole cell expansion upon waterlogging. PMID:24363315

  16. Deposition and localization of lipid polyester in developing seeds of Brassica napus and Arabidopsis thaliana.

    PubMed

    Molina, Isabel; Ohlrogge, John B; Pollard, Mike

    2008-02-01

    Mature seeds of Arabidopsis thaliana and Brassica napus contain complex mixtures of aliphatic monomers derived from non-extractable lipid polyesters. Most of the monomers are deposited in the seed coat, and their compositions suggest the presence of both cutin and suberin layers. The location of these polyesters within the seed coat, and their contributions to permeability of the seed coat and other functional properties are unknown. Polyester deposition was followed over Brassica seed development and distinct temporal patterns of monomer accumulation were observed. Octadecadiene-1,18-dioate, the major leaf cutin monomer, was transiently deposited. In contrast, the saturated dicarboxylates maintained a constant level during seed desiccation, whereas the fatty alcohols and saturated omega-hydroxy fatty acids continually increased. Dissection and analysis of Brassica seed coats showed that suberization is not specific to the chalaza. Analysis of the Arabidopsis ap2-7 mutant suggested that suberin monomers are preferentially associated with the outer integument. Several Arabidopsis knockout mutant lines for genes involved in polyester biosynthesis (att1, fatB and gpat5) were examined for seed monomer load and composition. The variance in polyester monomers of these mutants is correlated with dye penetration assays. Furthermore, stable transgenic plants expressing promoter::YFP fusions showed ATT1 promoter activity in the inner integument, whereas GPAT5 promoter is active in the outer integument. Together, the Arabidopsis data indicated that there is a suberized layer associated with the outer integument and a cutin-like polyester layer associated with the inner seed coat. PMID:18179651

  17. Interaction of proline, sugars, and anthocyanins during photosynthetic acclimation of Arabidopsis thaliana to drought stress.

    PubMed

    Sperdouli, Ilektra; Moustakas, Michael

    2012-04-15

    The relationships among photosynthetic acclimation, proline (Pro), soluble sugar (SS), and anthocyanin (An) accumulation in Arabidopsis thaliana leaves to the onset of drought stress (OnDS), mild (MiDS) and moderate drought stress (MoDS), were evaluated. As leaf water content (LWC) decreased, metabolic concentrations (Pro, SS, and An) increased and were negatively and significantly correlated with LWC. Thus, these metabolites may have an important role in the acclimation process to drought stress (DS). No correlations among Pro, SS and An accumulation with the quantum efficiency of PSII photochemistry (Φ(PSII)) and the excitation pressure (1-q(P)) were observed under DS. This implies that, while metabolites increased in a drought-dependent way, PSII activity did not decrease in the same pattern. Our results indicated that, under MoDS, A. thaliana leaves were able to maintain oxidative compounds such as malondialdeyde, an end product of lipid peroxidation, within the range of control leaves, and to cope with oxidative damage, as was evident by the decreased excitation pressure (1-q(P)) and similar (ns difference) Φ(PSII) to that of control leaves. In addition, a statistically significant increased accumulation of Pro, SS and An was recorded only under MoDS compared to controls. The better PSII functioning of MoDS Arabidopsis leaves may reflect the greater capacity of these leaves to undertake key metabolic adjustments, including increased Pro, SS and An accumulation, to maintain a higher antioxidant protection and a better balance between light capture and energy use. PMID:22305050

  18. Fusarium oxysporum Triggers Tissue-Specific Transcriptional Reprogramming in Arabidopsis thaliana

    PubMed Central

    Lyons, Rebecca; Stiller, Jiri; Powell, Jonathan; Rusu, Anca; Manners, John M.; Kazan, Kemal

    2015-01-01

    Some of the most devastating agricultural diseases are caused by root-infecting pathogens, yet the majority of studies on these interactions to date have focused on the host responses of aerial tissues rather than those belowground. Fusarium oxysporum is a root-infecting pathogen that causes wilt disease on several plant species including Arabidopsis thaliana. To investigate and compare transcriptional changes triggered by F. oxysporum in different Arabidopsis tissues, we infected soil-grown plants with F. oxysporum and subjected root and leaf tissue harvested at early and late timepoints to RNA-seq analyses. At least half of the genes induced or repressed by F. oxysporum showed tissue-specific regulation. Regulators of auxin and ABA signalling, mannose binding lectins and peroxidases showed strong differential expression in root tissue. We demonstrate that ARF2 and PRX33, two genes regulated in the roots, promote susceptibility to F. oxysporum. In the leaves, defensins and genes associated with the response to auxin, cold and senescence were strongly regulated while jasmonate biosynthesis and signalling genes were induced throughout the plant. PMID:25849296

  19. Identification of a tolerant locus on Arabidopsis thaliana to hypervirulent beet curly top virus CFH strain.

    PubMed

    Park, Seong-Hee; Hur, Jinkyung; Park, Jongbum; Lee, Sangseob; Lee, Taek-Kyun; Chang, Man; Davi, Keith R; Kim, Jeongha; Lee, Sukchan

    2002-04-30

    The infection of hosts by the geminivirus depends on the interactions between host and viral factors for viral DNA replication, viral gene expression, and the movement of virus throughout the hosts. This work reports that a hypervirulent strain of Beet curly top virus (BCTV) is different in its ability to infect several ecotypes of Arabidopsis thaliana. Symptoms appeared on Arabidopsis ecotypes around 7 to 10 d after inoculation with BCTV-CFH. Symptoms were more severe in ecotype SKKU including severe leaf curling and development of severely deformed and stunted boting compared to Col-O as a lab standard ecotype. One ecotype Cen-O was asymptomatic to BCTV-CFH infection. Studies of viral DNA replication and virus movement in three excised organs of asymptomatic Cen-O demonstrated that BCTV-CFH could replicate viral DNA and move systemically in this ecotype, suggesting that tolerance was due to the blocks of interactions between host and viral factors on symptom development. This asymptomatic phenotype is similar to the mutation of leftward ORFs, especially ORF R2. Genetic analysis of this ecotype Cen-O indicated that tolerance is due to a single recessive locus. PMID:12018847

  20. Landscape of the lipidome and transcriptome under heat stress in Arabidopsis thaliana

    PubMed Central

    Higashi, Yasuhiro; Okazaki, Yozo; Myouga, Fumiyoshi; Shinozaki, Kazuo; Saito, Kazuki

    2015-01-01

    Environmental stress causes membrane damage in plants. Lipid studies are required to understand the adaptation of plants to climate change. Here, LC-MS-based lipidomic and microarray transcriptome analyses were carried out to elucidate the effect of short-term heat stress on the Arabidopsis thaliana leaf membrane. Vegetative plants were subjected to high temperatures for one day, and then grown under normal conditions. Sixty-six detected glycerolipid species were classified according to patterns of compositional change by Spearman’s correlation coefficient. Triacylglycerols, 36:4- and 36:5-monogalactosyldiacylglycerol, 34:2- and 36:2-digalactosyldiacylglycerol, 34:1-, 36:1- and 36:6-phosphatidylcholine, and 34:1-phosphatidylethanolamine increased by the stress and immediately decreased during recovery. The relative amount of one triacylglycerol species (54:9) containing α-linolenic acid (18:3) increased under heat stress. These results suggest that heat stress in Arabidopsis leaves induces an increase in triacylglycerol levels, which functions as an intermediate of lipid turnover, and results in a decrease in membrane polyunsaturated fatty acids. Microarray data revealed candidate genes responsible for the observed metabolic changes. PMID:26013835

  1. Ion channels in guard cells of Arabidopsis thaliana (L.) Heynh..

    PubMed

    Roelfsema, M R; Prins, H B

    1997-01-01

    Despite the availability of many mutants for signal transduction, Arabidopsis thaliana guard cells have so far not been used in electrophysiological research. Problems with the isolation of epidermal strips and the small size of A. thaliana guard cells were often prohibiting. In the present study these difficulties were overcome and guard cells were impaled with double-barreled microelectrodes. Membrane-potential recordings were often stable for over half an hour and voltage-clamp measurements could be conducted. The guard cells were found to exhibit two states. The majority of the guard cells had depolarized membrane potentials, which were largely dependent on external K+ concentrations. Other cells displayed spontaneous transitions to a more hyperpolarized state, at which the free-running membrane potential (Em) was not sensitive to the external K+ concentration. Two outward-rectifying conductances were identified in cells in the depolarized state. A slow outward-rectifying channel (s-ORC) had properties resembling the K(+)-selective ORC of Vicia faba guard cells (Blatt, 1988, J Membr Biol 102: 235-246). The activation and inactivation times and the activation potential, all depended on the reversal potential (Erev) of the s-ORC conductance. The s-ORC was blocked by Ba2+ (K1/2 = 0.3-1.3 mM) and verapamil (K1/2 = 15-20 microM). A second rapid outward-rectifying conductance (r-ORC) activated instantaneously upon stepping the voltage to positive values and was stimulated by Ba2+. Inward-rectifying channels (IRC) were only observed in cells in the hyperpolarized state. The activation time and activation potential of this channel were not sensitive to the external K+ concentration. The slow activation of the IRC (t1/2 approximately 0.5 s) and its negative activation potential (Vthreshold = -155 mV) resemble the values found for the KAT1 channel expressed in Saccharomyces cerevisiae (Bertl et al., 1995, Proc Natl Acad Sci USA 92: 2701-2705). The results indicate that A

  2. Control of seed development in Arabidopsis thaliana by atmospheric oxygen

    NASA Technical Reports Server (NTRS)

    Kuang, A.; Crispi, M.; Musgrave, M. E.

    1998-01-01

    Seed development is known to be inhibited completely when plants are grown in oxygen concentrations below 5.1 kPa, but apart from reports of decreased seed weight little is known about embryogenesis at subambient oxygen concentrations above this critical level. Arabidopsis thaliana (L.) Heynh. plants were grown full term under continuous light in premixed atmospheres with oxygen partial pressures of 2.5, 5.1, 10.1, 16.2 and 21.3 kPa O2, 0.035 kPa CO2 and the balance nitrogen. Seeds were harvested for germination tests and microscopy when siliques had yellowed. Seed germination was depressed in O2 treatments below 16.2 kPa, and seeds from plants grown in 2.5 kPa O2 did not germinate at all. Fewer than 25% of the seeds from plants grown in 5.1 kPa oxygen germinated and most of the seedlings appeared abnormal. Light and scanning electron microscopic observation of non-germinated seeds showed that these embryos had stopped growing at different developmental stages depending upon the prevailing oxygen level. Embryos stopped growing at the heart-shaped to linear cotyledon stage in 5.1 kPa O2, at around the curled cotyledon stage in 10.1 kPa O2, and at the premature stage in 16.2 kPa O2. Globular and heart-shaped embryos were observed in sectioned seeds from plants grown in 2.5 kPa O2. Tissue degeneration caused by cell autolysis and changes in cell structure were observed in cotyledons and radicles. Transmission electron microscopy of mature seeds showed that storage substances, such as protein bodies, were reduced in subambient oxygen treatments. The results demonstrate control of embryo development by oxygen in Arabidopsis.

  3. Enhancement of Thiamin Content in Arabidopsis thaliana by Metabolic Engineering.

    PubMed

    Dong, Wei; Stockwell, Virginia O; Goyer, Aymeric

    2015-12-01

    Thiamin is an essential nutrient in the human diet. Severe thiamin deficiency leads to beriberi, a lethal disease which is common in developing countries. Thiamin biofortification of staple food crops is a possible strategy to alleviate thiamin deficiency-related diseases. In plants, thiamin plays a role in the response to abiotic and biotic stresses, and data from the literature suggest that boosting thiamin content could increase resistance to stresses. Here, we tested an engineering strategy to increase thiamin content in Arabidopsis. Thiamin is composed of a thiazole ring linked to a pyrimidine ring by a methylene bridge. THI1 and THIC are the first committed steps in the synthesis of the thiazole and pyrimidine moieties, respectively. Arabidopsis plants were transformed with a vector containing the THI1-coding sequence under the control of a constitutive promoter. Total thiamin leaf content in THI1 plants was up approximately 2-fold compared with the wild type. THI1-overexpressing lines were then crossed with pre-existing THIC-overexpressing lines. Resulting THI1 × THIC plants accumulated up to 3.4- and 2.6-fold more total thiamin than wild-type plants in leaf and seeds, respectively. After inoculation with Pseudomonas syringae, THI1 × THIC plants had lower populations than the wild-type control. However, THI1 × THIC plants subjected to various abiotic stresses did not show any visible or biochemical changes compared with the wild type. We discuss the impact of engineering thiamin biosynthesis on the nutritional value of plants and their resistance to biotic and abiotic stresses. PMID:26454882

  4. Mechanical induction of lateral root initiation in Arabidopsis thaliana

    PubMed Central

    Ditengou, Franck Anicet; Teale, William D.; Kochersperger, Philip; Flittner, Karl Andreas; Kneuper, Irina; van der Graaff, Eric; Nziengui, Hugues; Pinosa, Francesco; Li, Xugang; Nitschke, Roland; Laux, Thomas; Palme, Klaus

    2008-01-01

    Lateral roots are initiated postembryonically in response to environmental cues, enabling plants to explore efficiently their underground environment. However, the mechanisms by which the environment determines the position of lateral root formation are unknown. In this study, we demonstrate that in Arabidopsis thaliana lateral root initiation can be induced mechanically by either gravitropic curvature or by the transient bending of a root by hand. The plant hormone auxin accumulates at the site of lateral root induction before a primordium starts to form. Here we describe a subcellular relocalization of PIN1, an auxin transport protein, in a single protoxylem cell in response to gravitropic curvature. This relocalization precedes auxin-dependent gene transcription at the site of a new primordium. Auxin-dependent nuclear signaling is necessary for lateral root formation; arf7/19 double knock-out mutants normally form no lateral roots but do so upon bending when the root tip is removed. Signaling through arf7/19 can therefore be bypassed by root bending. These data support a model in which a root-tip-derived signal acts on downstream signaling molecules that specify lateral root identity. PMID:19033199

  5. Internet Resources for Gene Expression Analysis in Arabidopsis thaliana.

    PubMed

    Hehl, Reinhard; Bülow, Lorenz

    2008-09-01

    The number of online databases and web-tools for gene expression analysis in Arabidopsis thaliana has increased tremendously during the last years. These resources permit the database-assisted identification of putative cis-regulatory DNA sequences, their binding proteins, and the determination of common cis-regulatory motifs in coregulated genes. DNA binding proteins may be predicted by the type of cis-regulatory motif. Further questions of combinatorial control based on the interaction of DNA binding proteins and the colocalization of cis-regulatory motifs can be addressed. The database-assisted spatial and temporal expression analysis of DNA binding proteins and their target genes may help to further refine experimental approaches. Signal transduction pathways upstream of regulated genes are not yet fully accessible in databases mainly because they need to be manually annotated. This review focuses on the use of the AthaMap and PathoPlant((R)) databases for gene expression regulation analysis and discusses similar and complementary online databases and web-tools. Online databases are helpful for the development of working hypothesis and for designing subsequent experiments. PMID:19506727

  6. Internet Resources for Gene Expression Analysis in Arabidopsis thaliana

    PubMed Central

    Hehl, Reinhard; Bülow, Lorenz

    2008-01-01

    The number of online databases and web-tools for gene expression analysis in Arabidopsis thaliana has increased tremendously during the last years. These resources permit the database-assisted identification of putative cis-regulatory DNA sequences, their binding proteins, and the determination of common cis-regulatory motifs in coregulated genes. DNA binding proteins may be predicted by the type of cis-regulatory motif. Further questions of combinatorial control based on the interaction of DNA binding proteins and the colocalization of cis-regulatory motifs can be addressed. The database-assisted spatial and temporal expression analysis of DNA binding proteins and their target genes may help to further refine experimental approaches. Signal transduction pathways upstream of regulated genes are not yet fully accessible in databases mainly because they need to be manually annotated. This review focuses on the use of the AthaMap and PathoPlant® databases for gene expression regulation analysis and discusses similar and complementary online databases and web-tools. Online databases are helpful for the development of working hypothesis and for designing subsequent experiments. PMID:19506727

  7. Transcriptional responses of Arabidopsis thaliana plants to As (V) stress

    PubMed Central

    Abercrombie, Jason M; Halfhill, Matthew D; Ranjan, Priya; Rao, Murali R; Saxton, Arnold M; Yuan, Joshua S; Stewart, C Neal

    2008-01-01

    Background Arsenic is toxic to plants and a common environmental pollutant. There is a strong chemical similarity between arsenate [As (V)] and phosphate (Pi). Whole genome oligonucleotide microarrays were employed to investigate the transcriptional responses of Arabidopsis thaliana plants to As (V) stress. Results Antioxidant-related genes (i.e. coding for superoxide dismutases and peroxidases) play prominent roles in response to arsenate. The microarray experiment revealed induction of chloroplast Cu/Zn superoxide dismutase (SOD) (at2g28190), Cu/Zn SOD (at1g08830), as well as an SOD copper chaperone (at1g12520). On the other hand, Fe SODs were strongly repressed in response to As (V) stress. Non-parametric rank product statistics were used to detect differentially expressed genes. Arsenate stress resulted in the repression of numerous genes known to be induced by phosphate starvation. These observations were confirmed with qRT-PCR and SOD activity assays. Conclusion Microarray data suggest that As (V) induces genes involved in response to oxidative stress and represses transcription of genes induced by phosphate starvation. This study implicates As (V) as a phosphate mimic in the cell by repressing genes normally induced when available phosphate is scarce. Most importantly, these data reveal that arsenate stress affects the expression of several genes with little or unknown biological functions, thereby providing new putative gene targets for future research. PMID:18684332

  8. Arabidopsis thaliana nucleosidase mutants provide new insights into nucleoside degradation

    PubMed Central

    Riegler, Heike; Geserick, Claudia; Zrenner, Rita

    2011-01-01

    A central step in nucleoside and nucleobase salvage pathways is the hydrolysis of nucleosides to their respective nucleobases. In plants this is solely accomplished by nucleosidases (EC 3.2.2.x). To elucidate the importance of nucleosidases for nucleoside degradation, general metabolism, and plant growth, thorough phenotypic and biochemical analyses were performed using Arabidopsis thaliana T-DNA insertion mutants lacking expression of the previously identified genes annotated as uridine ribohydrolases (URH1 and URH2). Comprehensive functional analyses of single and double mutants demonstrated that both isoforms are unimportant for seedling establishment and plant growth, while one participates in uridine degradation. Rather unexpectedly, nucleoside and nucleotide profiling and nucleosidase activity screening of soluble crude extracts revealed a deficiency of xanthosine and inosine hydrolysis in the single mutants, with substantial accumulation of xanthosine in one of them. Mixing of the two mutant extracts, and by in vitro activity reconstitution using a mixture of recombinant URH1 and URH2 proteins, both restored activity, thus providing biochemical evidence that at least these two isoforms are needed for inosine and xanthosine hydrolysis. This mutant study demonstrates the utility of in vivo systems for the examination of metabolic activities, with the discovery of the new substrate xanthosine and elucidation of a mechanism for expanding the nucleosidase substrate spectrum. PMID:21599668

  9. Lagging adaptation to warming climate in Arabidopsis thaliana

    PubMed Central

    Wilczek, Amity M.; Cooper, Martha D.; Korves, Tonia M.; Schmitt, Johanna

    2014-01-01

    If climate change outpaces the rate of adaptive evolution within a site, populations previously well adapted to local conditions may decline or disappear, and banked seeds from those populations will be unsuitable for restoring them. However, if such adaptational lag has occurred, immigrants from historically warmer climates will outperform natives and may provide genetic potential for evolutionary rescue. We tested for lagging adaptation to warming climate using banked seeds of the annual weed Arabidopsis thaliana in common garden experiments in four sites across the species’ native European range: Valencia, Spain; Norwich, United Kingdom; Halle, Germany; and Oulu, Finland. Genotypes originating from geographic regions near the planting site had high relative fitness in each site, direct evidence for broad-scale geographic adaptation in this model species. However, genotypes originating in sites historically warmer than the planting site had higher average relative fitness than local genotypes in every site, especially at the northern range limit in Finland. This result suggests that local adaptive optima have shifted rapidly with recent warming across the species’ native range. Climatic optima also differed among seasonal germination cohorts within the Norwich site, suggesting that populations occurring where summer germination is common may have greater evolutionary potential to persist under future warming. If adaptational lag has occurred over just a few decades in banked seeds of an annual species, it may be an important consideration for managing longer-lived species, as well as for attempts to conserve threatened populations through ex situ preservation. PMID:24843140

  10. Induction of Anthocyanin Accumulation by Cytokinins in Arabidopsis thaliana.

    PubMed Central

    Deikman, J.; Hammer, P. E.

    1995-01-01

    Arabidopsis thaliana plants treated with exogenous cytokinins accumulate anthocyanin pigments. We have characterized this response because it is potentially useful as a genetic marker for cytokinin responsiveness. Levels of mRNAs for four genes of the anthocyanin biosynthesis pathway, phenylalanine ammonia lyase 1 (PAL1), chalcone synthase (CHS), chalcone isomerase (CHI), and dihydroflavonol reductase (DFR) were shown to increase coordinately in response to benzyladenine (BA). However, nuclear run-on transcription experiments suggested that although CHS and DFR are controlled by BA at the transcriptional level, PAL1 and CHI are controlled by BA posttranscriptionally. CHS mRNA levels increased within 2 h of BA spray application, and peaked by 3 h. Levels of PAL1 mRNA did not increase within 6 h of BA spray. We also showed that PAL1, CHS, CHI, and DFR mRNA levels fluctuate during a 24-h period and appear to be controlled by a circadian clock. The relation between cytokinin regulation and light regulation of CHS gene transcription is discussed. PMID:12228453

  11. Spatial control of flowering by DELLA proteins in Arabidopsis thaliana.

    PubMed

    Galvão, Vinicius C; Horrer, Daniel; Küttner, Frank; Schmid, Markus

    2012-11-01

    The transition from vegetative to reproductive development is a central event in the plant life cycle. To time the induction of flowering correctly, plants integrate environmental and endogenous signals such as photoperiod, temperature and hormonal status. The hormone gibberellic acid (GA) has long been known to regulate flowering. However, the spatial contribution of GA signaling in flowering time control is poorly understood. Here we have analyzed the effect of tissue-specific misexpression of wild-type and GA-insensitive (dellaΔ17) DELLA proteins on the floral transition in Arabidopsis thaliana. We demonstrate that under long days, GA affects the floral transition by promoting the expression of flowering time integrator genes such as FLOWERING LOCUS T (FT) and TWIN SISTER OF FT (TSF) in leaves independently of CONSTANS (CO) and GIGANTEA (GI). In addition, GA signaling promotes flowering independently of photoperiod through the regulation of SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) genes in both the leaves and at the shoot meristem. Our data suggest that GA regulates flowering by controlling the spatial expression of floral regulatory genes throughout the plant in a day-length-specific manner. PMID:22992955

  12. Regulation of Arabidopsis thaliana 5S rRNA Genes.

    PubMed

    Vaillant, Isabelle; Tutois, Sylvie; Cuvillier, Claudine; Schubert, Ingo; Tourmente, Sylvette

    2007-05-01

    The Arabidopsis thaliana genome comprises around 1,000 copies of 5S rRNA genes encoding both major and minor 5S rRNAs. In mature wild-type leaves, the minor 5S rRNA genes are silent. Using different mutants of DNA methyltransferases (met1, cmt3 and met1 cmt3), components of the RNAi pathway (ago4) or post-translational histone modifier (hda6/sil1), we show that the corresponding proteins are needed to maintain proper methylation patterns at heterochromatic 5S rDNA repeats. Using reverse transcription-PCR and cytological analyses, we report that a decrease of 5S rDNA methylation at CG or CNG sites in these mutants leads to the release of 5S rRNA gene silencing which occurred without detectable changes of the 5S rDNA chromatin structure. In spite of severely reduced DNA methylation, the met1 cmt3 double mutant revealed no increase in minor 5S rRNA transcripts. Furthermore, the release of silencing of minor 5S rDNAs can be achieved without increased formation of euchromatic loops by 5S rDNA, and is independent from the global heterochromatin content. Additionally, fluorescence in situ hybridization with centromeric 180 bp repeats confirmed that these highly repetitive sequences, in spite of their elevated transcriptional activity in the DNA methyltransferase mutants (met1, cmt3 and met1 cmt3), remain within chromocenters of the mutant nuclei. PMID:17412735

  13. Genome-level evolution of resistance genes in Arabidopsis thaliana.

    PubMed Central

    Baumgarten, Andrew; Cannon, Steven; Spangler, Russ; May, Georgiana

    2003-01-01

    Pathogen resistance genes represent some of the most abundant and diverse gene families found within plant genomes. However, evolutionary mechanisms generating resistance gene diversity at the genome level are not well understood. We used the complete Arabidopsis thaliana genome sequence to show that most duplication of individual NBS-LRR sequences occurs at close physical proximity to the parent sequence and generates clusters of closely related NBS-LRR sequences. Deploying the statistical strength of phylogeographic approaches and using chromosomal location as a proxy for spatial location, we show that apparent duplication of NBS-LRR genes to ectopic chromosomal locations is largely the consequence of segmental chromosome duplication and rearrangement, rather than the independent duplication of individual sequences. Although accounting for a smaller fraction of NBS-LRR gene duplications, segmental chromosome duplication and rearrangement events have a large impact on the evolution of this multigene family. Intergenic exchange is dramatically lower between NBS-LRR sequences located in different chromosome regions as compared to exchange between sequences within the same chromosome region. Consequently, once translocated to new chromosome locations, NBS-LRR gene copies have a greater likelihood of escaping intergenic exchange and adopting new functions than do gene copies located within the same chromosomal region. We propose an evolutionary model that relates processes of genome evolution to mechanisms of evolution for the large, diverse, NBS-LRR gene family. PMID:14504238

  14. Epigenomic Diversity in a Global Collection of Arabidopsis thaliana Accessions.

    PubMed

    Kawakatsu, Taiji; Huang, Shao-Shan Carol; Jupe, Florian; Sasaki, Eriko; Schmitz, Robert J; Urich, Mark A; Castanon, Rosa; Nery, Joseph R; Barragan, Cesar; He, Yupeng; Chen, Huaming; Dubin, Manu; Lee, Cheng-Ruei; Wang, Congmao; Bemm, Felix; Becker, Claude; O'Neil, Ryan; O'Malley, Ronan C; Quarless, Danjuma X; Schork, Nicholas J; Weigel, Detlef; Nordborg, Magnus; Ecker, Joseph R

    2016-07-14

    The epigenome orchestrates genome accessibility, functionality, and three-dimensional structure. Because epigenetic variation can impact transcription and thus phenotypes, it may contribute to adaptation. Here, we report 1,107 high-quality single-base resolution methylomes and 1,203 transcriptomes from the 1001 Genomes collection of Arabidopsis thaliana. Although the genetic basis of methylation variation is highly complex, geographic origin is a major predictor of genome-wide DNA methylation levels and of altered gene expression caused by epialleles. Comparison to cistrome and epicistrome datasets identifies associations between transcription factor binding sites, methylation, nucleotide variation, and co-expression modules. Physical maps for nine of the most diverse genomes reveal how transposons and other structural variants shape the epigenome, with dramatic effects on immunity genes. The 1001 Epigenomes Project provides a comprehensive resource for understanding how variation in DNA methylation contributes to molecular and non-molecular phenotypes in natural populations of the most studied model plant. PMID:27419873

  15. Epigenetic variation contributes to environmental adaptation of Arabidopsis thaliana

    PubMed Central

    Kooke, Rik; Keurentjes, Joost J B

    2015-01-01

    Epigenetic variation is frequently observed in plants and direct relationships between differences in DNA methylation and phenotypic responses to changing environments have often been described. The identification of contributing genetic loci, however, was until recently hampered by the lack of suitable genome wide mapping resources that specifically segregate for epigenetic marks. The development of epi-RIL populations in the model species Arabidopsis thaliana has alleviated this obstacle, enabling the accurate genetic analysis of epigenetic variation. Comprehensive morphological phenotyping of a ddm1 derived epi-RIL population in different environments and subsequent epi-QTL mapping revealed a high number of epi-QTLs and pleiotropic effects of several DMRs on numerous traits. For a number of these epi-QTLs epistatic interactions could be observed, further adding to the complexity of epigenetic regulation. Moreover, linkage to epigenetic marks indicated a specific role for DNA-methylation variation, rather than TE transposition, in plastic responses to changing environments. These findings provide supportive evidence for a role of epigenetic regulation in evolutionary and adaptive processes. PMID:26237693

  16. Genetic analysis of salt-tolerant mutants in Arabidopsis thaliana.

    PubMed Central

    Quesada, V; Ponce, M R; Micol, J L

    2000-01-01

    Stress caused by the increased salinity of irrigated fields impairs plant growth and is one of the major constraints that limits crop productivity in many important agricultural areas. As a contribution to solving such agronomic problems, we have carried out a large-scale screening for Arabidopsis thaliana mutants induced on different genetic backgrounds by EMS treatment, fast neutron bombardment, or T-DNA insertions. From the 675,500 seeds we screened, 17 mutant lines were isolated, all but one of which yielded 25-70% germination levels on 250 mm NaCl medium, a condition in which their ancestor ecotypes are unable to germinate. Monogenic recessive inheritance of NaCl-tolerant germination was displayed with incomplete penetrance by all the selected mutants, which fell into five complementation groups. These were named SALOBRENO (SAN) and mapped relative to polymorphic microsatellites, the map positions of three of them suggesting that they are novel genes. Strains carrying mutations in the SAN1-SAN4 genes display similar responses to both ionic effects and osmotic pressure, their germination being NaCl and mannitol tolerant but KCl and Na(2)SO(4) sensitive. In addition, NaCl-, KCl-, and mannitol-tolerant as well as abscisic-acid-insensitive germination was displayed by sañ5, whose genetic and molecular characterization indicates that it carries an extremely hypomorphic or null allele of the ABI4 gene, its deduced protein product lacking the APETALA2 DNA binding domain. PMID:10629000

  17. Gene prediction and gene classes in Arabidopsis thaliana.

    PubMed

    Mathé, C; Déhais, P; Pavy, N; Rombauts, S; Van Montagu, M; Rouzé, P

    2000-03-31

    Gene prediction methods for eukaryotic genomes still are not fully satisfying. One way to improve gene prediction accuracy, proven to be relevant for prokaryotes, is to consider more than one model of genes. Thus, we used our classification of Arabidopsis thaliana genes in two classes (CU(1) and CU(2)), previously delineated according to statistical features, in the GeneMark gene identification program. For each gene class, as well as for the two classes combined, a Markov model was developed (respectively, GM-CU(1), GM-CU(2) and GM-all) and then used on a test set of 168 genes to compare their respective efficiency. We concluded from this analysis that GM-CU(1) is more sensitive than GM-CU(2) which seems to be more specific to a gene type. Besides, GM-all does not give better results than GM-CU(1) and combining results from GM-CU(1) and GM-CU(2) greatly improve prediction efficiency in comparison with predictions made with GM-all only. Thus, this work confirms the necessity to consider more than one gene model for gene prediction in eukaryotic genomes, and to look for gene classes in order to build these models. PMID:10751690

  18. Plant cell wall proteomics: the leadership of Arabidopsis thaliana

    PubMed Central

    Albenne, Cécile; Canut, Hervé; Jamet, Elisabeth

    2013-01-01

    Plant cell wall proteins (CWPs) progressively emerged as crucial components of cell walls although present in minor amounts. Cell wall polysaccharides such as pectins, hemicelluloses, and cellulose represent more than 90% of primary cell wall mass, whereas hemicelluloses, cellulose, and lignins are the main components of lignified secondary walls. All these polymers provide mechanical properties to cell walls, participate in cell shape and prevent water loss in aerial organs. However, cell walls need to be modified and customized during plant development and in response to environmental cues, thus contributing to plant adaptation. CWPs play essential roles in all these physiological processes and particularly in the dynamics of cell walls, which requires organization and rearrangements of polysaccharides as well as cell-to-cell communication. In the last 10 years, plant cell wall proteomics has greatly contributed to a wider knowledge of CWPs. This update will deal with (i) a survey of plant cell wall proteomics studies with a focus on Arabidopsis thaliana; (ii) the main protein families identified and the still missing peptides; (iii) the persistent issue of the non-canonical CWPs; (iv) the present challenges to overcome technological bottlenecks; and (v) the perspectives beyond cell wall proteomics to understand CWP functions. PMID:23641247

  19. Adaptation response of Arabidopsis thaliana to random positioning

    NASA Astrophysics Data System (ADS)

    Kittang, A.-I.; Winge, P.; van Loon, J. J. W. A.; Bones, A. M.; Iversen, T.-H.

    2013-10-01

    Arabidopsis thaliana seedlings were exposed on a Random Positioning Machine (RPM) under light conditions for 16 h and the samples were analysed using microarray techniques as part of a preparation for a space experiment on the International Space Station (ISS). The results demonstrated a moderate to low regulation of 55 genes (<0.2% of the analysed genes). Genes encoding proteins associated with the chaperone system (e.g. heat shock proteins, HSPs) and enzymes in the flavonoid biosynthesis were induced. Most of the repressed genes were associated with light and sugar responses. Significant up-regulation of selected HSP genes was found by quantitative Real-Time PCR in 1 week old plants after the RPM exposure both in light and darkness. Higher quantity of DPBA (diphenylboric acid 2-amino-ethyl ester) staining was observed in the whole root and in the root elongation zone of the seedlings exposed on the RPM by use of fluorescent microscopy, indicating higher flavonoid content. The regulated genes and an increase of flavonoids are related to several stresses, but increased occurrence of HSPs and flavonoids are also representative for normal growth (e.g. gravitropism). The response could be a direct stress response or an integrated response of the two signal pathways of light and gravity resulting in an overall light response.

  20. Characterization of adaptation in phototropism of Arabidopsis thaliana

    NASA Technical Reports Server (NTRS)

    Poff, K. L.

    1991-01-01

    Phototropic curvature has been measured for etiolated Arabidopsis thaliana seedlings with and without a preirradiation. A bilateral preirradiation with 450-nm light at a fluence greater than about 0.1 micromole per square meter causes a rapid desensitization to a subsequent 450-nanometer unilateral irradiation at 0.5 micromole per square meter. Following a refractory period, the capacity to respond phototropically recovers to the predesensitization level, and the response is then enhanced. The length of the refractory period is between 10 and 20 minutes. Both the time needed for recovery and the extent of enhancement increase with increasing fluence of the bilateral preirradiation. Based on the relative spectral sensitivities of desensitization and enhancement, these responses can be separated. Desensitization is induced by blue light but not by red light. Enhancement, however, is induced by both blue and red light. Thus, enhancement can be induced without desensitization but not vice versa. Both desensitization and enhancement affect only the magnitude of the response and do not affect the fluence threshold.

  1. Desensitization and recovery of phototropic responsiveness in Arabidopsis thaliana

    NASA Technical Reports Server (NTRS)

    Janoudi, A. K.; Poff, K. L.

    1993-01-01

    Phototropism is induced by blue light, which also induces desensitization, a partial or total loss of phototropic responsiveness. The fluence and fluence-rate dependence of desensitization and recovery from desensitization have been measured for etiolated and red light (669-nm) preirradiated Arabidopsis thaliana seedlings. The extent of desensitization increased as the fluence of the desensitizing 450-nm light was increased from 0.3 to 60 micromoles m-2 s-1. At equal fluences, blue light caused more desensitization when given at a fluence rate of 1.0 micromole m-2 s-1 than at 0.3 micromole m-2 s-1. In addition, seedlings irradiated with blue light at the higher fluence rate required a longer recovery time than seedlings irradiated at the lower fluence rate. A red light preirradiation, probably mediated via phytochrome, decreased the time required for recovery from desensitization. The minimum time for detectable recovery was about 65 s, and the maximum time observed was about 10 min. It is proposed that the descending arm of the fluence-response relationship for first positive phototropism is a consequence of desensitization, and that the time threshold for second positive phototropism establishes a period during which recovery from desensitization occurs.

  2. Ligand migration and binding in nonsymbiotic hemoglobins of Arabidopsis thaliana.

    PubMed

    Nienhaus, Karin; Dominici, Paola; Astegno, Alessandra; Abbruzzetti, Stefania; Viappiani, Cristiano; Nienhaus, G Ulrich

    2010-09-01

    We have studied carbon monoxide (CO) migration and binding in the nonsymbiotic hemoglobins AHb1 and AHb2 of Arabidopsis thaliana using Fourier transform infrared (FTIR) spectroscopy combined with temperature derivative spectroscopy (TDS) at cryogenic temperatures. Both proteins have similar amino acid sequences but display pronounced differences in ligand binding properties, at both physiological and cryogenic temperatures. Near neutral pH, the distal HisE7 side chain is close to the heme-bound ligand in the majority of AHb1-CO molecules, as indicated by a low CO stretching frequency at 1921 cm(-1). In this fraction, two CO docking sites can be populated, the primary site B and the secondary site C. When the pH is lowered, a high-frequency stretching band at approximately 1964 cm(-1) grows at the expense of the low-frequency band, indicating that HisE7 protonates and, concomitantly, moves away from the bound ligand. Geminate rebinding barriers are markedly different for the two conformations, and docking site C is not accessible in the low-pH conformation. Rebinding of NO ligands was observed only from site B of AHb1, regardless of conformation. In AHb2, the HisE7 side chain is removed from the bound ligand; rebinding barriers are low, and CO molecules can populate only primary docking site B. These results are interpreted in terms of differences in the active site structures and physiological functions. PMID:20666470

  3. Proteomic analyses of apoplastic proteins from germinating Arabidopsis thaliana pollen

    PubMed Central

    Ge, Weina; Song, Yun; Zhang, Cuijun; Zhang, Yafang; Burlingame, Alma L.; Guo, Yi

    2011-01-01

    Pollen grains play important roles in the reproductive processes of flowering plants. The roles of apoplastic proteins in pollen germination and in pollen tube growth are comparatively less well understood. To investigate the functions of apoplastic proteins in pollen germination, the global apoplastic proteins of mature and germinated Arabidopsis thaliana pollen grains were prepared for differential analyses by using 2-dimensional fluorescence difference gel electrophoresis (2-D DIGE) saturation labeling techniques. One hundred and three proteins differentially expressed (p value ≤ 0.01) in pollen germinated for 6h compare with un-germination mature pollen, and 98 spots, which represented 71 proteins, were identified by LC-MS/MS. By bioinformatics analysis, 50 proteins were identified as secreted proteins. These proteins were mainly involved in cell wall modification and remodeling, protein metabolism and signal transduction. Three of the differentially expressed proteins were randomly selected to determine their subcellular localizations by transiently expressing YFP fusion proteins. The results of subcellular localization were identical with the bioinformatics prediction. Based on these data, we proposed a model for apoplastic proteins functioning in pollen germination and pollen tube growth. These results will lead to a better understanding of the mechanisms of pollen germination and pollen tube growth. PMID:21798377

  4. Desensitization and recovery of phototropic responsiveness in Arabidopsis thaliana.

    PubMed Central

    Janoudi, A K; Poff, K L

    1993-01-01

    Phototropism is induced by blue light, which also induces desensitization, a partial or total loss of phototropic responsiveness. The fluence and fluence-rate dependence of desensitization and recovery from desensitization have been measured for etiolated and red light (669-nm) preirradiated Arabidopsis thaliana seedlings. The extent of desensitization increased as the fluence of the desensitizing 450-nm light was increased from 0.3 to 60 micromoles m-2 s-1. At equal fluences, blue light caused more desensitization when given at a fluence rate of 1.0 micromole m-2 s-1 than at 0.3 micromole m-2 s-1. In addition, seedlings irradiated with blue light at the higher fluence rate required a longer recovery time than seedlings irradiated at the lower fluence rate. A red light preirradiation, probably mediated via phytochrome, decreased the time required for recovery from desensitization. The minimum time for detectable recovery was about 65 s, and the maximum time observed was about 10 min. It is proposed that the descending arm of the fluence-response relationship for first positive phototropism is a consequence of desensitization, and that the time threshold for second positive phototropism establishes a period during which recovery from desensitization occurs. PMID:11537496

  5. Lagging adaptation to warming climate in Arabidopsis thaliana.

    PubMed

    Wilczek, Amity M; Cooper, Martha D; Korves, Tonia M; Schmitt, Johanna

    2014-06-01

    If climate change outpaces the rate of adaptive evolution within a site, populations previously well adapted to local conditions may decline or disappear, and banked seeds from those populations will be unsuitable for restoring them. However, if such adaptational lag has occurred, immigrants from historically warmer climates will outperform natives and may provide genetic potential for evolutionary rescue. We tested for lagging adaptation to warming climate using banked seeds of the annual weed Arabidopsis thaliana in common garden experiments in four sites across the species' native European range: Valencia, Spain; Norwich, United Kingdom; Halle, Germany; and Oulu, Finland. Genotypes originating from geographic regions near the planting site had high relative fitness in each site, direct evidence for broad-scale geographic adaptation in this model species. However, genotypes originating in sites historically warmer than the planting site had higher average relative fitness than local genotypes in every site, especially at the northern range limit in Finland. This result suggests that local adaptive optima have shifted rapidly with recent warming across the species' native range. Climatic optima also differed among seasonal germination cohorts within the Norwich site, suggesting that populations occurring where summer germination is common may have greater evolutionary potential to persist under future warming. If adaptational lag has occurred over just a few decades in banked seeds of an annual species, it may be an important consideration for managing longer-lived species, as well as for attempts to conserve threatened populations through ex situ preservation. PMID:24843140

  6. Purification and properties of porphobilinogen deaminase from Arabidopsis thaliana.

    PubMed Central

    Jones, R M; Jordan, P M

    1994-01-01

    Porphobilinogen deaminase (EC 4.3.1.8) has been purified to homogeneity (16,000-fold) from the plant Arabidopsis thaliana in yields of 8%. The deaminase is a monomer of M(r) 35,000, as shown by SDS/PAGE, and 31,000, using gel-filtration chromatography. The pure enzyme has a Vmax. of 4.5 mumol/h per mg and a Km of 17 +/- 4 microM. Determination of the pI and pH optimum revealed values of 5.2 and 8.0 respectively. The sequence of the N-terminus was found to be NH2-XVAVEQKTRTAI. The deaminase is heat-stable up to 70 degrees C and is inhibited by NH3 and hydroxylamine. The enzyme is inactivated by arginine-, histidine- and lysine-specific reagents. Incubation with the substrate analogue and suicide inhibitor, 2-bromoporphobilinogen, results in chain termination and in inactivation. Images Figure 1 PMID:8192681

  7. Protein composition of oil bodies in Arabidopsis thaliana ecotype WS.

    PubMed

    Jolivet, Pascale; Roux, Emeline; D'Andrea, Sabine; Davanture, Marlène; Negroni, Luc; Zivy, Michel; Chardot, Thierry

    2004-06-01

    Till now, only scattered data are available in the literature, which describes the protein content of plant oil bodies. Especially, the proteins closely associated with the model plant Arabidopsis thaliana oil bodies have never been previously purified and characterized. Oil bodies have been purified using flotation techniques, combined with incubations under high salt concentration, in the presence of detergents and urea in order to remove non-specifically trapped proteins. The identity and integrity of the oil bodies have been characterized. Oil bodies exhibited hydrodynamic diameters close to 2.6 microm, and a ratio fatty acid-protein content near 20. The proteins composing these organelles were extracted, separated by SDS-PAGE, digested by trypsin, and their peptides were subsequently analyzed by nano-chromatography-mass spectrometry (nano-LC-MS/MS). This led to the identification of a limited number of proteins: four different oleosins, ATS1, a protein homologous to calcium binding protein, a 11-beta-hydroxysteroid dehydrogenase-like protein, a probable aquaporin and a glycosylphosphatidylinositol-anchored protein with no known function. The two last proteins were till now never identified in plant oil bodies. Structural proteins (oleosins) represented up to 79% of oil body proteins and the 18.5 kDa oleosin was the most abundant among them. PMID:15246063

  8. Interactions among Genes Regulating Ovule Development in Arabidopsis Thaliana

    PubMed Central

    Baker, S. C.; Robinson-Beers, K.; Villanueva, J. M.; Gaiser, J. C.; Gasser, C. S.

    1997-01-01

    The INNER NO OUTER (INO) and AINTEGUMENTA (ANT) genes are essential for ovule integument development in Arabidopsis thaliana. Ovules of ino mutants initiate two integument primordia, but the outer integument primordium forms on the opposite side of the ovule from the normal location and undergoes no further development. The inner integument appears to develop normally, resulting in erect, unitegmic ovules that resemble those of gymnosperms. ino plants are partially fertile and produce seeds with altered surface topography, demonstrating a lineage dependence in development of the testa. ant mutations affect initiation of both integuments. The strongest of five new ant alleles we have isolated produces ovules that lack integuments and fail to complete megasporogenesis. ant mutations also affect flower development, resulting in narrow petals and the absence of one or both lateral stamens. Characterization of double mutants between ant, ino and other mutations affecting ovule development has enabled the construction of a model for genetic control of ovule development. This model proposes parallel independent regulatory pathways for a number of aspects of this process, a dependence on the presence of an inner integument for development of the embryo sac, and the existence of additional genes regulating ovule development. PMID:9093862

  9. Pollen and ovule development in Arabidopsis thaliana under spaceflight conditions

    NASA Technical Reports Server (NTRS)

    Kuang, A.; Musgrave, M. E.; Matthews, S. W.; Cummins, D. B.; Tucker, S. C.

    1995-01-01

    The development of pollen and ovules in Arabidopsis thaliana on the space shuttle 'Endeavour' (STS-54) was investigated. Plants were grown on nutrient agar for 14 days prior to loading into closed plant growth chambers that received light and temperature control inside the Plant Growth Unit flight hardware on the shuttle middeck. After 6 days in spaceflight the plants were retrieved and immediately dissected and processed for light and electron microscope observation. Reproductive development aborted at an early stage. Pistils were collapsed and ovules inside were seen to he empty. No viable pollen was observed from STS-54 plants; young microspores were deformed and empty. At a late stage, the cytoplasm of the pollen contracted and became disorganized, but the pollen wall developed and the exine appeared normal. The tapetum in the flight flowers degenerated at early stages. Ovules from STS-54 flight plants stopped growing and the integuments and nucellus collapsed and degenerated. The megasporocytes appeared abnormal and rarely underwent meiosis. Apparently they enlarged, or occasionally produced a dyad or tetrad, to assume the form of a female gametophyte with the single nucleus located in an egglike cell that lacks a cell wall. Synergids, polar nuclei, and antipodals were not observed. The results demonstrate the types of lesions occurring in plant reproductive material under spaceflight conditions.

  10. Plastid DNA polymerases from higher plants, Arabidopsis thaliana

    SciTech Connect

    Mori, Yoko; Kimura, Seisuke; Saotome, Ai; Kasai, Nobuyuki; Sakaguchi, Norihiro; Uchiyama, Yukinobu; Ishibashi, Toyotaka; Yamamoto, Taichi; Chiku, Hiroyuki; Sakaguchi, Kengo . E-mail: kengo@rs.noda.sut.ac.jp

    2005-08-19

    Previously, we described a novel DNA polymerase, designated as OsPolI-like, from rice. The OsPolI-like showed a high degree of sequence homology with the DNA polymerase I of cyanobacteria and was localized in the plastid. Here, we describe two PolI-like polymerases, designated as AtPolI-like A and AtPolI-like B, from Arabidopsis thaliana. In situ hybridization analysis demonstrated expression of both mRNAs in proliferating tissues such as the shoot apical meristem. Analysis of the localizations of GFP fusion proteins showed that AtPolI-like A and AtPolI-like B were localized to plastids. AtPolI-like B expression could be induced by exposure to the mutagen H{sub 2}O{sub 2}. These results suggested that AtPolI-like B has a role in the repair of oxidation-induced DNA damage. Our data indicate that higher plants possess two plastid DNA polymerases that are not found in animals and yeasts.

  11. Plant Vascular Architecture Determines the Pattern of Herbivore-Induced Systemic Responses in Arabidopsis thaliana

    PubMed Central

    Ferrieri, Abigail P.; Appel, Heidi M.; Schultz, Jack C.

    2015-01-01

    The induction of systemic responses in plants is associated with the connectivity between damaged and undamaged leaves, as determined by vascular architecture. Despite the widespread appreciation for studying variation in induced plant defense, few studies have characterized spatial variability of induction in the model species, Arabidopsis thaliana. Here we show that plant architecture generates fine scale spatial variation in the systemic induction of invertase and phenolic compounds. We examined whether the arrangement of leaves along the stem (phyllotaxy) produces predictable spatial patterns of cell-wall bound and soluble invertase activities, and downstream phenolic accumulation following feeding by the dietary specialist herbivore, Pieris rapae and the generalist, Spodoptera exigua. Responses were measured in leaves within and outside of the damaged orthostichy (leaves sharing direct vascular connections), and compared to those from plants where source-sink transport was disrupted by source leaf removal and by an insertional mutation in a sucrose transporter gene (suc2-1). Following herbivore damage to a single, middle-aged leaf, induction of cell-wall and soluble invertase was most pronounced in young and old leaves within the damaged orthostichy. The pattern of accumulation of phenolics was also predicted by these vascular connections and was, in part, dependent on the presence of source leaves and intact sucrose transporter function. Induction also occurred in leaves outside of the damaged orthostichy, suggesting that mechanisms may exist to overcome vascular constraints in this system. Our results demonstrate that systemic responses vary widely according to orthostichy, are often herbivore-specific, and partially rely on transport between source and sink leaves. We also provide evidence that patterns of induction are more integrated in A. thaliana than previously described. This work highlights the importance of plant vascular architecture in determining

  12. Plant vascular architecture determines the pattern of herbivore-induced systemic responses in Arabidopsis thaliana.

    PubMed

    Ferrieri, Abigail P; Appel, Heidi M; Schultz, Jack C

    2015-01-01

    The induction of systemic responses in plants is associated with the connectivity between damaged and undamaged leaves, as determined by vascular architecture. Despite the widespread appreciation for studying variation in induced plant defense, few studies have characterized spatial variability of induction in the model species, Arabidopsis thaliana. Here we show that plant architecture generates fine scale spatial variation in the systemic induction of invertase and phenolic compounds. We examined whether the arrangement of leaves along the stem (phyllotaxy) produces predictable spatial patterns of cell-wall bound and soluble invertase activities, and downstream phenolic accumulation following feeding by the dietary specialist herbivore, Pieris rapae and the generalist, Spodoptera exigua. Responses were measured in leaves within and outside of the damaged orthostichy (leaves sharing direct vascular connections), and compared to those from plants where source-sink transport was disrupted by source leaf removal and by an insertional mutation in a sucrose transporter gene (suc2-1). Following herbivore damage to a single, middle-aged leaf, induction of cell-wall and soluble invertase was most pronounced in young and old leaves within the damaged orthostichy. The pattern of accumulation of phenolics was also predicted by these vascular connections and was, in part, dependent on the presence of source leaves and intact sucrose transporter function. Induction also occurred in leaves outside of the damaged orthostichy, suggesting that mechanisms may exist to overcome vascular constraints in this system. Our results demonstrate that systemic responses vary widely according to orthostichy, are often herbivore-specific, and partially rely on transport between source and sink leaves. We also provide evidence that patterns of induction are more integrated in A. thaliana than previously described. This work highlights the importance of plant vascular architecture in determining

  13. The use of artificial microRNA technology to control gene expression in Arabidopsis thaliana.

    PubMed

    Eamens, Andrew L; McHale, Marcus; Waterhouse, Peter M

    2014-01-01

    In plants, double-stranded RNA (dsRNA) is an effective trigger of RNA silencing, and several classes of endogenous small RNA (sRNA), processed from dsRNA substrates by DICER-like (DCL) endonucleases, are essential in controlling gene expression. One such sRNA class, the microRNAs (miRNAs) control the expression of closely related genes to regulate all aspects of plant development, including the determination of leaf shape, leaf polarity, flowering time, and floral identity. A single miRNA sRNA silencing signal is processed from a long precursor transcript of nonprotein-coding RNA, termed the primary miRNA (pri-miRNA). A region of the pri-miRNA is partially self-complementary allowing the transcript to fold back onto itself to form a stem-loop structure of imperfectly dsRNA. Artificial miRNA (amiRNA) technology uses endogenous pri-miRNAs, in which the miRNA and miRNA* (passenger strand of the miRNA duplex) sequences have been replaced with corresponding amiRNA/amiRNA* sequences that direct highly efficient RNA silencing of the targeted gene. Here, we describe the rules for amiRNA design, as well as outline the PCR and bacterial cloning procedures involved in the construction of an amiRNA plant expression vector to control target gene expression in Arabidopsis thaliana. PMID:24057368

  14. 2-Deoxy-2-fluoro-d-glucose metabolism in Arabidopsis thaliana

    PubMed Central

    Fatangare, Amol; Paetz, Christian; Saluz, Hanspeter; Svatoš, Aleš

    2015-01-01

    2-Deoxy-2-fluoro-d-glucose (FDG) is glucose analog routinely used in clinical and animal radiotracer studies to trace glucose uptake but it has rarely been used in plants. Previous studies analyzed FDG translocation and distribution pattern in plants and proposed that FDG could be used as a tracer for photoassimilates in plants. Elucidating FDG metabolism in plants is a crucial aspect for establishing its application as a radiotracer in plant imaging. Here, we describe the metabolic fate of FDG in the model plant species Arabidopsis thaliana. We fed FDG to leaf tissue and analyzed leaf extracts using MS and NMR. On the basis of exact mono-isotopic masses, MS/MS fragmentation, and NMR data, we identified 2-deoxy-2-fluoro-gluconic acid, FDG-6-phosphate, 2-deoxy-2-fluoro-maltose, and uridine-diphosphate-FDG as four major end products of FDG metabolism. Glycolysis and starch degradation seemed to be the important pathways for FDG metabolism. We showed that FDG metabolism in plants is considerably different than animal cells and goes beyond FDG-phosphate as previously presumed. PMID:26579178

  15. The pharmaceutics from the foreign empire: the molecular pharming of the prokaryotic staphylokinase in Arabidopsis thaliana plants.

    PubMed

    Hnatuszko-Konka, Katarzyna; Łuchniak, Piotr; Wiktorek-Smagur, Aneta; Gerszberg, Aneta; Kowalczyk, Tomasz; Gatkowska, Justyna; Kononowicz, Andrzej K

    2016-07-01

    Here, we present the application of microbiology and biotechnology for the production of recombinant pharmaceutical proteins in plant cells. To the best of our knowledge and belief it is one of few examples of the expression of the prokaryotic staphylokinase (SAK) in the eukaryotic system. Despite the tremendous progress made in the plant biotechnology, most of the heterologous proteins still accumulate to low concentrations in plant tissues. Therefore, the composition of expression cassettes to assure economically feasible level of protein production in plants remains crucial. The aim of our research was obtaining a high concentration of the bacterial anticoagulant factor-staphylokinase, in Arabidopsis thaliana seeds. The coding sequence of staphylokinase was placed under control of the β-phaseolin promoter and cloned between the signal sequence of the seed storage protein 2S2 and the carboxy-terminal KDEL signal sequence. The engineered binary vector pATAG-sak was introduced into Arabidopsis thaliana plants via Agrobacterium tumefaciens-mediated transformation. Analysis of the subsequent generations of Arabidopsis seeds revealed both presence of the sak and nptII transgenes, and the SAK protein. Moreover, a plasminogen activator activity of staphylokinase was observed in the protein extracts from seeds, while such a reaction was not observed in the leaf extracts showing seed-specific activity of the β-phaseolin promoter. PMID:27263008

  16. A small GTP-binding protein from Arabidopsis thaliana functionally complements the yeast YPT6 null mutant.

    PubMed Central

    Bednarek, S Y; Reynolds, T L; Schroeder, M; Grabowski, R; Hengst, L; Gallwitz, D; Raikhel, N V

    1994-01-01

    A clone designated A.t.RAB6 encoding a small GTP-binding protein was isolated from a cDNA library of Arabidopsis thaliana leaf tissue. The predicted amino acid sequence was highly homologous to the mammalian and yeast counterparts, H.Rab6 and Ryh1/Ypt6, respectively. Lesser homology was found between the predicted Arabidopsis protein sequence and two small GTP-binding proteins isolated from plant species (44% homology to Zea mays Ypt1 and 43% homology to Nicotiana tabacum Rab5). Conserved stretches in the deduced amino acid sequence of A.t.Rab6 include four regions involved in GTP-binding, an effector region, and C-terminal cysteine residues required for prenylation and subsequent membrane attachment. Northern blot analysis demonstrated that A.t.Rab6 mRNA was expressed in root, leaf, stem, and flower tissues from A. thaliana with the highest levels present in roots. Escherichia coli produced histidine-tagged A.t.Rab6 protein-bound GTP, whereas a mutation in one of the guanine nucleotide-binding sites (asparagine122 to isoleucine) rendered it incapable of binding GTP. Functionally, the A.t.RAB6 gene was able to complement the temperature-sensitive phenotype of the YPT6 null mutant in yeast. The isolation of this gene will aid in the dissection of the machinery involved in soluble protein sorting at the trans-Golgi network of plants. PMID:8159788

  17. Differentially phased leaf growth and movements in Arabidopsis depend on coordinated circadian and light regulation.

    PubMed

    Dornbusch, Tino; Michaud, Olivier; Xenarios, Ioannis; Fankhauser, Christian

    2014-10-01

    In contrast to vastly studied hypocotyl growth, little is known about diel regulation of leaf growth and its coordination with movements such as changes in leaf elevation angle (hyponasty). We developed a 3D live-leaf growth analysis system enabling simultaneous monitoring of growth and movements. Leaf growth is maximal several hours after dawn, requires light, and is regulated by daylength, suggesting coupling between growth and metabolism. We identify both blade and petiole positioning as important components of leaf movements in Arabidopsis thaliana and reveal a temporal delay between growth and movements. In hypocotyls, the combination of circadian expression of PHYTOCHROME INTERACTING FACTOR4 (PIF4) and PIF5 and their light-regulated protein stability drives rhythmic hypocotyl elongation with peak growth at dawn. We find that PIF4 and PIF5 are not essential to sustain rhythmic leaf growth but influence their amplitude. Furthermore, EARLY FLOWERING3, a member of the evening complex (EC), is required to maintain the correct phase between growth and movement. Our study shows that the mechanisms underlying rhythmic hypocotyl and leaf growth differ. Moreover, we reveal the temporal relationship between leaf elongation and movements and demonstrate the importance of the EC for the coordination of these phenotypic traits. PMID:25281688

  18. Structural diversity and transcription of class III peroxidases from Arabidopsis thaliana.

    PubMed

    Welinder, Karen G; Justesen, Annemarie F; Kjaersgård, Inger V H; Jensen, Rikke B; Rasmussen, Søren K; Jespersen, Hans M; Duroux, Laurent

    2002-12-01

    Understanding peroxidase function in plants is complicated by the lack of substrate specificity, the high number of genes, their diversity in structure and our limited knowledge of peroxidase gene transcription and translation. In the present study we sequenced expressed sequence tags (ESTs) encoding novel heme-containing class III peroxidases from Arabidopsis thaliana and annotated 73 full-length genes identified in the genome. In total, transcripts of 58 of these genes have now been observed. The expression of individual peroxidase genes was assessed in organ-specific EST libraries and compared to the expression of 33 peroxidase genes which we analyzed in whole plants 3, 6, 15, 35 and 59 days after sowing. Expression was assessed in root, rosette leaf, stem, cauline leaf, flower bud and cell culture tissues using the gene-specific and highly sensitive reverse transcriptase-polymerase chain reaction (RT-PCR). We predicted that 71 genes could yield stable proteins folded similarly to horseradish peroxidase (HRP). The putative mature peroxidases derived from these genes showed 28-94% amino acid sequence identity and were all targeted to the endoplasmic reticulum by N-terminal signal peptides. In 20 peroxidases these signal peptides were followed by various N-terminal extensions of unknown function which are not present in HRP. Ten peroxidases showed a C-terminal extension indicating vacuolar targeting. We found that the majority of peroxidase genes were expressed in root. In total, class III peroxidases accounted for an impressive 2.2% of root ESTs. Rather few peroxidases showed organ specificity. Most importantly, genes expressed constitutively in all organs and genes with a preference for root represented structurally diverse peroxidases (< 70% sequence identity). Furthermore, genes appearing in tandem showed distinct expression profiles. The alignment of 73 Arabidopsis peroxidase sequences provides an easy access to the identification of orthologous peroxidases

  19. Yeast cell wall extract induces disease resistance against bacterial and fungal pathogens in Arabidopsis thaliana and Brassica crop.

    PubMed

    Narusaka, Mari; Minami, Taichi; Iwabuchi, Chikako; Hamasaki, Takashi; Takasaki, Satoko; Kawamura, Kimito; Narusaka, Yoshihiro

    2015-01-01

    Housaku Monogatari (HM) is a plant activator prepared from a yeast cell wall extract. We examined the efficacy of HM application and observed that HM treatment increased the resistance of Arabidopsis thaliana and Brassica rapa leaves to bacterial and fungal infections. HM reduced the severity of bacterial leaf spot and anthracnose on A. thaliana and Brassica crop leaves with protective effects. In addition, gene expression analysis of A. thaliana plants after treatment with HM indicated increased expression of several plant defense-related genes. HM treatment appears to induce early activation of jasmonate/ethylene and late activation of salicylic acid (SA) pathways. Analysis using signaling mutants revealed that HM required SA accumulation and SA signaling to facilitate resistance to the bacterial pathogen Pseudomonas syringae pv. maculicola and the fungal pathogen Colletotrichum higginsianum. In addition, HM-induced resistance conferred chitin-independent disease resistance to bacterial pathogens in A. thaliana. These results suggest that HM contains multiple microbe-associated molecular patterns that activate defense responses in plants. These findings suggest that the application of HM is a useful tool that may facilitate new disease control methods. PMID:25565273

  20. Yeast Cell Wall Extract Induces Disease Resistance against Bacterial and Fungal Pathogens in Arabidopsis thaliana and Brassica Crop

    PubMed Central

    Narusaka, Mari; Minami, Taichi; Iwabuchi, Chikako; Hamasaki, Takashi; Takasaki, Satoko; Kawamura, Kimito; Narusaka, Yoshihiro

    2015-01-01

    Housaku Monogatari (HM) is a plant activator prepared from a yeast cell wall extract. We examined the efficacy of HM application and observed that HM treatment increased the resistance of Arabidopsis thaliana and Brassica rapa leaves to bacterial and fungal infections. HM reduced the severity of bacterial leaf spot and anthracnose on A. thaliana and Brassica crop leaves with protective effects. In addition, gene expression analysis of A. thaliana plants after treatment with HM indicated increased expression of several plant defense-related genes. HM treatment appears to induce early activation of jasmonate/ethylene and late activation of salicylic acid (SA) pathways. Analysis using signaling mutants revealed that HM required SA accumulation and SA signaling to facilitate resistance to the bacterial pathogen Pseudomonas syringae pv. maculicola and the fungal pathogen Colletotrichum higginsianum. In addition, HM-induced resistance conferred chitin-independent disease resistance to bacterial pathogens in A. thaliana. These results suggest that HM contains multiple microbe-associated molecular patterns that activate defense responses in plants. These findings suggest that the application of HM is a useful tool that may facilitate new disease control methods. PMID:25565273

  1. GROWTH REGULATING FACTOR5 Stimulates Arabidopsis Chloroplast Division, Photosynthesis, and Leaf Longevity1[OPEN

    PubMed Central

    Vercruyssen, Liesbeth; Tognetti, Vanesa B.; Gonzalez, Nathalie; Van Dingenen, Judith; De Milde, Liesbeth; Bielach, Agnieszka; De Rycke, Riet; Van Breusegem, Frank; Inzé, Dirk

    2015-01-01

    Arabidopsis (Arabidopsis thaliana) leaf development relies on subsequent phases of cell proliferation and cell expansion. During the proliferation phase, chloroplasts need to divide extensively, and during the transition from cell proliferation to expansion, they differentiate into photosynthetically active chloroplasts, providing the plant with energy. The transcription factor GROWTH REGULATING FACTOR5 (GRF5) promotes the duration of the cell proliferation period during leaf development. Here, it is shown that GRF5 also stimulates chloroplast division, resulting in a higher chloroplast number per cell with a concomitant increase in chlorophyll levels in 35S:GRF5 leaves, which can sustain higher rates of photosynthesis. Moreover, 35S:GRF5 plants show delayed leaf senescence and are more tolerant for growth on nitrogen-depleted medium. Cytokinins also stimulate leaf growth in part by extending the cell proliferation phase, simultaneously delaying the onset of the cell expansion phase. In addition, cytokinins are known to be involved in chloroplast development, nitrogen signaling, and senescence. Evidence is provided that GRF5 and cytokinins synergistically enhance cell division and chlorophyll retention after dark-induced senescence, which suggests that they also cooperate to stimulate chloroplast division and nitrogen assimilation. Taken together with the increased leaf size, ectopic expression of GRF5 has great potential to improve plant productivity. PMID:25604530

  2. Purification of a. beta. -amylase that accumulates in Arabidopsis thaliana mutants defective in starch metabolism. [Arabidopsis thaliana

    SciTech Connect

    Monroe, J.D.; Preiss, J. )

    1990-11-01

    Amylase activity is elevated 5- to 10-fold in leaves of several different Arabidopsis thaliana mutants defective in starch metabolism when they are grown under a 12-hour photoperiod. Activity is also increased when plants are grown under higher light intensity. It was previously determined that the elevated activity was an extrachloroplastic {beta}-(exo)amylase. Due to the location of this enzyme outside the chloroplast, its function is not known. The enzyme was purified to homogeneity from leaves of both a starchless mutant deficient in plastid phosphoglucomutase and from the wild type using polyethylene glycol fractionation and cyclohexaamylose affinity chromatography. The molecular mass of the {beta}-amylase from both sources was 55,000 daltons as determined by denaturing gel electrophoresis. Gel filtration studies indicated that the enzyme was a monomer. The specific activities of the purified protein from mutant and wild-type sources, their substrate specificities, and K{sub m} for amylopectin were identical. Based on these results it was concluded that the mutant contained an increased level of {beta}-amylase protein. Enzyme neutralization studies using a polyclonal antiserum raised to purified {beta}-amylase showed that in each of two starchless mutants, one starch deficient mutant and one starch overproducing mutant, the elevated amylase activity was due to elevated {beta}-amylase protein.

  3. The roles of genetic drift and natural selection in quantitative trait divergence along an altitudinal gradient in Arabidopsis thaliana

    PubMed Central

    Luo, Y; Widmer, A; Karrenberg, S

    2015-01-01

    Understanding how natural selection and genetic drift shape biological variation is a central topic in biology, yet our understanding of the agents of natural selection and their target traits is limited. We investigated to what extent selection along an altitudinal gradient or genetic drift contributed to variation in ecologically relevant traits in Arabidopsis thaliana. We collected seeds from 8 to 14 individuals from each of 14 A. thaliana populations originating from sites between 800 and 2700 m above sea level in the Swiss Alps. Seed families were grown with and without vernalization, corresponding to winter-annual and summer-annual life histories, respectively. We analyzed putatively neutral genetic divergence between these populations using 24 simple sequence repeat markers. We measured seven traits related to growth, phenology and leaf morphology that are rarely reported in A. thaliana and performed analyses of altitudinal clines, as well as overall QST-FST comparisons and correlation analyses among pair-wise QST, FST and altitude of origin differences. Multivariate analyses suggested adaptive differentiation along altitude in the entire suite of traits, particularly when expressed in the summer-annual life history. Of the individual traits, a decrease in rosette leaf number in the vegetative state and an increase in leaf succulence with increasing altitude could be attributed to adaptive divergence. Interestingly, these patterns relate well to common within- and between-species trends of smaller plant size and thicker leaves at high altitude. Our results thus offer exciting possibilities to unravel the underlying mechanisms for these conspicuous trends using the model species A. thaliana. PMID:25293874

  4. Drought Stress Predominantly Endures Arabidopsis thaliana to Pseudomonas syringae Infection.

    PubMed

    Gupta, Aarti; Dixit, Sandeep K; Senthil-Kumar, Muthappa

    2016-01-01

    Plant responses to a combination of drought and bacterial pathogen infection, an agronomically important and altogether a new stress, are not well-studied. While occurring concurrently, these two stresses can lead to synergistic or antagonistic effects on plants due to stress-interaction. It is reported that plant responses to the stress combinations consist of both strategies, unique to combined stress and those shared between combined and individual stresses. However, the combined stress response mechanisms governing stress interaction and net impact are largely unknown. In order to study these adaptive strategies, an accurate and convenient methodology is lacking even in model plants like Arabidopsis thaliana. The gradual nature of drought stress imposition protocol poses a hindrance in simultaneously applying pathogen infection under laboratory conditions to achieve combined stress. In present study we aimed to establish systematic combined stress protocol and to study physiological responses of the plants to various degrees of combined stress. Here, we have comprehensively studied the impact of combined drought and Pseudomonas syringae pv. tomato DC3000 infection on A. thaliana. Further, by employing different permutations of drought and pathogen stress intensities, an attempt was made to dissect the contribution of each individual stress effects during their concurrence. We hereby present two main aspects of combined stress viz., stress interaction and net impact of the stress on plants. Mainly, this study established a systematic protocol to assess the impact of combined drought and bacterial pathogen stress. It was observed that as a result of net impact, some physiological responses under combined stress are tailored when compared to the plants exposed to individual stresses. We also infer that plant responses under combined stress in this study are predominantly influenced by the drought stress. Our results show that pathogen multiplication was reduced by

  5. Drought Stress Predominantly Endures Arabidopsis thaliana to Pseudomonas syringae Infection

    PubMed Central

    Gupta, Aarti; Dixit, Sandeep K.; Senthil-Kumar, Muthappa

    2016-01-01

    Plant responses to a combination of drought and bacterial pathogen infection, an agronomically important and altogether a new stress, are not well-studied. While occurring concurrently, these two stresses can lead to synergistic or antagonistic effects on plants due to stress-interaction. It is reported that plant responses to the stress combinations consist of both strategies, unique to combined stress and those shared between combined and individual stresses. However, the combined stress response mechanisms governing stress interaction and net impact are largely unknown. In order to study these adaptive strategies, an accurate and convenient methodology is lacking even in model plants like Arabidopsis thaliana. The gradual nature of drought stress imposition protocol poses a hindrance in simultaneously applying pathogen infection under laboratory conditions to achieve combined stress. In present study we aimed to establish systematic combined stress protocol and to study physiological responses of the plants to various degrees of combined stress. Here, we have comprehensively studied the impact of combined drought and Pseudomonas syringae pv. tomato DC3000 infection on A. thaliana. Further, by employing different permutations of drought and pathogen stress intensities, an attempt was made to dissect the contribution of each individual stress effects during their concurrence. We hereby present two main aspects of combined stress viz., stress interaction and net impact of the stress on plants. Mainly, this study established a systematic protocol to assess the impact of combined drought and bacterial pathogen stress. It was observed that as a result of net impact, some physiological responses under combined stress are tailored when compared to the plants exposed to individual stresses. We also infer that plant responses under combined stress in this study are predominantly influenced by the drought stress. Our results show that pathogen multiplication was reduced by

  6. Perspectives on Systematic Analyses of Gene Function in Arabidopsis thaliana: New Tools, Topics and Trends

    PubMed Central

    Bolle, C; Schneider, A; Leister, D

    2011-01-01

    Since the sequencing of the nuclear genome of Arabidopsis thaliana ten years ago, various large-scale analyses of gene function have been performed in this model species. In particular, the availability of collections of lines harbouring random T-DNA or transposon insertions, which include mutants for almost all of the ~27,000 A. thaliana genes, has been crucial for the success of forward and reverse genetic approaches. In the foreseeable future, genome-wide phenotypic data from mutant analyses will become available for Arabidopsis, and will stimulate a flood of novel in-depth gene-function analyses. In this review, we consider the present status of resources and concepts for systematic studies of gene function in A. thaliana. Current perspectives on the utility of loss-of-function and gain-of-function mutants will be discussed in light of the genetic and functional redundancy of many A. thaliana genes. PMID:21886450

  7. Genetic Analysis of Gravity Signal Transduction in Arabidopsis thaliana Seedlings

    NASA Astrophysics Data System (ADS)

    Boonsirichai, K.; Harrison, B.; Stanga, J.; Young, L.-S.; Neal, C.; Sabat, G.; Murthy, N.; Harms, A.; Sedbrook, J.; Masson, P.

    The primary roots of Arabidopsis thaliana seedlings respond to gravity stimulation by developing a tip curvature that results from differential cellular elongation on opposite flanks of the elongation zone. This curvature appears modulated by a lateral gradient of auxin that originates in the gravity-perceiving cells (statocytes) of the root cap through an apparent lateral repositioning of a component the auxin efflux carrier complex within these cells (Friml et al, 2002, Nature 415: 806-809). Unfortunately, little is known about the molecular mechanisms that govern early phases of gravity perception and signal transduction within the root-cap statocytes. We have used a molecular genetic approach to uncover some of these mechanisms. Mutations in the Arabidopsis ARG1 and ARL2 genes, which encode J-domain proteins, resulted in specific alterations in root and hypocotyl gravitropism, without pleiotropic phenotypes. Interestingly, ARG1 and ARL2 appear to function in the same genetic pathway. A combination of molecular genetic, biochemical and cell-biological approaches were used to demonstrate that ARG1 functions in early phases of gravity signal transduction within the root and hypocotyl statocytes, and is needed for efficient lateral auxin transport within the cap. The ARG1 protein is associated with components of the secretory and/or endosomal pathways, suggesting its role in the recycling of components of the auxin efflux carrier complex between plasma membrane and endosome (Boonsirichai et al, 2003, Plant Cell 15:2612-2625). Genetic modifiers of arg1-2 were isolated and shown to enhance the gravitropic defect of arg1-2, while resulting in little or no gravitropic defects in a wild type ARG1 background. A slight tendency for arg1-2;mar1-1 and arg1-2;mar2-1 double-mutant organs to display an opposite gravitropic response compared to wild type suggests that all three genes contribute to the interpretation of the gravity-vector information by seedling organs. The

  8. GFP Loss-of-Function Mutations in Arabidopsis thaliana

    PubMed Central

    Fu, Jason L.; Kanno, Tatsuo; Liang, Shih-Chieh; Matzke, Antonius J. M.; Matzke, Marjori

    2015-01-01

    Green fluorescent protein (GFP) and related fluorescent proteins are widely used in biological research to monitor gene expression and protein localization in living cells. The GFP chromophore is generated spontaneously in the presence of oxygen by a multi-step reaction involving cyclization of the internal tripeptide Ser65 (or Thr65)-Tyr66-Gly67, which is embedded in the center of an 11-stranded β-barrel structure. Random and site-specific mutagenesis has been used to optimize GFP fluorescence and create derivatives with novel properties. However, loss-of-function mutations that would aid in understanding GFP protein folding and chromophore formation have not been fully cataloged. Here we report a collection of ethyl methansulfonate–induced GFP loss-of-function mutations in the model plant Arabidopsis thaliana. Mutations that alter residues important for chromophore maturation, such as Arg96 and Ser205, greatly reduce or extinguish fluorescence without dramatically altering GFP protein accumulation. By contrast, other loss-of-fluorescence mutations substantially diminish the amount of GFP protein, suggesting that they compromise protein stability. Many mutations in this category generate substitutions of highly conserved glycine residues, including the following: Gly67 in the chromogenic tripeptide; Gly31, Gly33, and Gly35 in the second β-strand; and Gly20, Gly91, and Gly127 in the lids of the β-barrel scaffold. Our genetic analysis supports conclusions from structural and biochemical studies and demonstrates a critical role for multiple, highly conserved glycine residues in GFP protein stability. PMID:26153075

  9. Expression, purification and characterization of Arabidopsis thaliana acetohydroxyacid synthase.

    PubMed Central

    Chang, A K; Duggleby, R G

    1997-01-01

    Acetohydroxyacid synthase (EC 4.1.3.18) is the enzyme that catalyses the first step in the synthesis of the branched-chain amino acids valine, leucine and isoleucine. The AHAS gene from Arabidopsis thaliana with part of the chloroplast transit sequence removed was cloned into the bacterial expression vector pT7-7 and expressed in the Escherichia coli strain BL21(DE3). The expressed enzyme was purified by an extensive procedure involving (NH4)2SO4 fractionation followed by hydrophobic and anion-exchange chromatography. The purified enzyme appears as a single band on SDS/PAGE with a molecular mass of about 61 kDa. On gel filtration the enzyme is a dimer, migrating as a single peak with molecular masses of 109 and 113 kDa in the absence and presence of FAD respectively. Ion spray MS analysis yielded a mass of 63864 Da. The enzyme has optimum activity in the pH range 6.5-8.5 and exhibits absolute dependence on the three cofactors FAD, Mg2+ and thiamine diphosphate for activity. It displays negatively co-operative kinetics with respect to pyruvate concentration. A model was derived to explain the non-hyperbolic substrate-saturation curve, involving interaction between the active sites of the dimer. The Km for the first active site was found to be 8.01 +/- 0.66 mM; the Km for the second active site could not be accurately determined but was estimated to be approx. 100 mM. The enzyme is insensitive to valine, leucine and isoleucine but is strongly inhibited by the sulphonylurea herbicide, chlorsulphuron, and the imidazolinone herbicide, imazapyr. Inhibition by both herbicides exhibits slow-binding kinetics, whereas chlorsulphuron also shows tight-binding inhibition. PMID:9355748

  10. Characterization of Xanthophyll Pigments, Photosynthetic Performance, Photon Energy Dissipation, Reactive Oxygen Species Generation and Carbon Isotope Discrimination during Artemisinin-Induced Stress in Arabidopsis thaliana

    PubMed Central

    Hussain, M. Iftikhar; Reigosa, Manuel J.

    2015-01-01

    Artemisinin, a potent antimalarial drug, is phytotoxic to many crops and weeds. The effects of artemisinin on stress markers, including fluorescence parameters, photosystem II photochemistry, photon energy dissipation, lipid peroxidation, reactive oxygen species generation and carbon isotope discrimination in Arabidopsis thaliana were studied. Arabidopsis ecotype Columbia (Col-0) seedlings were grown in perlite and watered with 50% Hoagland nutrient solution. Adult plants of Arabidopsis were treated with artemisinin at 0, 40, 80, 160 μM for one week. Artemisinin, in the range 40–160 μM, decreased the fresh biomass, chl a, b and leaf mineral contents. Photosynthetic efficiency, yield and electron transport rate in Arabidopsis were also reduced following exposure to 80 and 160 μM artemisinin. The ΦNPQ and NPQ were less than control. Artemisinin treatment caused an increase in root oxidizability and lipid peroxidation (MDA contents) of Arabidopsis. Calcium and nitrogen contents decreased after 80 and 160 μM artemisinin treatment compared to control. δ13C values were less negative following treatment with artemisinin as compared to the control. Artemisinin also decreased leaf protein contents in Arabidopsis. Taken together, these data suggest that artemisinin inhibits many physiological and biochemical processes in Arabidopsis. PMID:25635811

  11. Characterization of xanthophyll pigments, photosynthetic performance, photon energy dissipation, reactive oxygen species generation and carbon isotope discrimination during artemisinin-induced stress in Arabidopsis thaliana.

    PubMed

    Hussain, M Iftikhar; Reigosa, Manuel J

    2015-01-01

    Artemisinin, a potent antimalarial drug, is phytotoxic to many crops and weeds. The effects of artemisinin on stress markers, including fluorescence parameters, photosystem II photochemistry, photon energy dissipation, lipid peroxidation, reactive oxygen species generation and carbon isotope discrimination in Arabidopsis thaliana were studied. Arabidopsis ecotype Columbia (Col-0) seedlings were grown in perlite and watered with 50% Hoagland nutrient solution. Adult plants of Arabidopsis were treated with artemisinin at 0, 40, 80, 160 μM for one week. Artemisinin, in the range 40-160 μM, decreased the fresh biomass, chl a, b and leaf mineral contents. Photosynthetic efficiency, yield and electron transport rate in Arabidopsis were also reduced following exposure to 80 and 160 μM artemisinin. The ΦNPQ and NPQ were less than control. Artemisinin treatment caused an increase in root oxidizability and lipid peroxidation (MDA contents) of Arabidopsis. Calcium and nitrogen contents decreased after 80 and 160 μM artemisinin treatment compared to control. δ13C values were less negative following treatment with artemisinin as compared to the control. Artemisinin also decreased leaf protein contents in Arabidopsis. Taken together, these data suggest that artemisinin inhibits many physiological and biochemical processes in Arabidopsis. PMID:25635811

  12. A Biochemical GC-MS Application for the Organic Chemistry Laboratory: Determination of Fatty Acid Composition of Arabidopsis thaliana Lipids

    NASA Astrophysics Data System (ADS)

    Bender, Jared D.; Catino, Arthur J., III.; Hess, Kenneth R.; Lassman, Michael E.; Leber, Phyllis A.; Reinard, Michael D.; Strotman, Neil A.; Pike, Carl S.

    2000-11-01

    A biochemical application of GC-MS in which students determine the qualitative and quantitative lipid composition of plant leaf samples is described. There are four facets of this project: (i) synthesis and characterization of individual fatty acid methyl esters (FAMEs) as standards for GC-MS analysis, (ii) isolation of the fatty acids of Arabidopsis thaliana leaves, both wild type and mutants, as FAMEs, (iii) GC-MS analysis of the Arabidopsis leaf extracts for fatty acid composition, and (iv) comparison of the class results with the literature data for both wild type and the four mutants and with a biochemical model of two pathways for lipid synthesis in Arabidopsis leaves. Because this experimental paradigm links organic synthesis and spectral characterization by IR and NMR, both 1H and 13C, with separation and identification via GC-MS analysis, all of the key areas of laboratory procedure are encompassed in this single project. The experimental design permits a myriad of hypothesis-testing variations. Plants can be grown at different temperatures and for different lengths of time to determine if and how fatty acid composition varies. Different types of plant leaves can be examined to ascertain if each has a unique fatty acid fingerprint.

  13. Crystallization of DIR1, a LTP2-like resistance signalling protein from Arabidopsis thaliana

    SciTech Connect

    Lascombe, Marie-Bernard; Buhot, Nathalie; Bakan, Bénédicte; Marion, Didier; Blein, Jean Pierre; Lamb, Chris J.; Prangé, Thierry

    2006-07-01

    DIR1, a putative LTP2 protein from Arabidopsis thaliana implicated in systemic acquired resistance in planta, has been crystallized in space group P2{sub 1}2{sub 1}2{sub 1} with one molecule per asymmetric unit. DIR1, a putative LTP2 protein from Arabidopsis thaliana implicated in systemic acquired resistance in planta, has been crystallized in space group P2{sub 1}2{sub 1}2{sub 1} with one molecule per asymmetric unit. The crystals diffract to a resolution of 1.6 Å.

  14. Comparative differential gene expression analysis of nucleus-encoded proteins for Rafflesia cantleyi against Arabidopsis thaliana

    NASA Astrophysics Data System (ADS)

    Ng, Siuk-Mun; Lee, Xin-Wei; Wan, Kiew-Lian; Firdaus-Raih, Mohd

    2015-09-01

    Regulation of functional nucleus-encoded proteins targeting the plastidial functions was comparatively studied for a plant parasite, Rafflesia cantleyi versus a photosynthetic plant, Arabidopsis thaliana. This study involved two species of different feeding modes and different developmental stages. A total of 30 nucleus-encoded proteins were found to be differentially-regulated during two stages in the parasite; whereas 17 nucleus-encoded proteins were differentially-expressed during two developmental stages in Arabidopsis thaliana. One notable finding observed for the two plants was the identification of genes involved in the regulation of photosynthesis-related processes where these processes, as expected, seem to be present only in the autotroph.

  15. Gravity perception and gravitropic response of inflorescence stems in Arabidopsis thaliana

    NASA Astrophysics Data System (ADS)

    Fukaki, H.; Tasaka, M.

    1999-01-01

    Shoots of higher plants exhibit negative gravitropism. However, little is known about the site of gravity perception in shoots and the molecular mechanisms of shoot gravitropic responses. Our recent analysis using shoot gravitropism1(sgr1)/scarecrow(scr) and sgr7/short-root (shr) mutants in Arabidopsis thaliana indicated that the endodermis is essential for shoot gravitropism and strongly suggested that the endodermis functions as the gravity-sensing cell layer in dicotyledonous plant shoots. In this paper, we present our recent analysis and model of gravity perception and gravitropic response of inflorescence stems in Arabidopsis thaliana.

  16. A Putative Chloroplast Thylakoid Metalloprotease VIRESCENT3 Regulates Chloroplast Development in Arabidopsis thaliana.

    PubMed

    Qi, Yafei; Liu, Xiayan; Liang, Shuang; Wang, Rui; Li, Yuanfeng; Zhao, Jun; Shao, Jingxia; An, Lijun; Yu, Fei

    2016-02-12

    The chloroplast is the site of photosynthesis and many other essential plant metabolic processes, and chloroplast development is an integral part of plant growth and development. Mutants defective in chloroplast development can display various color phenotypes including the intriguing virescence phenotype, which shows yellow/white coloration at the leaf base and greening toward the leaf tip. Through large scale genetic screens, we identified a series of new virescent mutants including virescent3-1 (vir3-1), vir4-1, and vir5-1 in Arabidopsis thaliana. We showed that VIR3 encodes a putative chloroplast metalloprotease by map-based cloning. Through site-directed mutagenesis, we showed that the conserved histidine 235 residue in the zinc binding motif HEAGH of VIR3 is indispensable for VIR3 accumulation in the chloroplast. The chloroplast localization of VIR3 was confirmed by the transient expression of VIR3-GFP in leaf protoplasts. Furthermore, taking advantage of transgenic lines expressing VIR3-FLAG, we demonstrated that VIR3 is an intrinsic thylakoid membrane protein that mainly resides in the stromal lamellae. Moreover, topology analysis using transgenic lines expressing a dual epitope-tagged VIR3 indicated that both the N and C termini of VIR3 are located in the stroma, and the catalytic domain of VIR3 is probably facing the stroma. Blue native gel analysis indicated that VIR3 is likely present as a monomer or part of a small complex in the thylakoid membrane. This work not only implicates VIR3 as a new factor involved in early chloroplast development but also provides more insight into the roles of chloroplast proteases in chloroplast biogenesis. PMID:26702056

  17. Functional overlap of the Arabidopsis leaf and root microbiota.

    PubMed

    Bai, Yang; Müller, Daniel B; Srinivas, Girish; Garrido-Oter, Ruben; Potthoff, Eva; Rott, Matthias; Dombrowski, Nina; Münch, Philipp C; Spaepen, Stijn; Remus-Emsermann, Mitja; Hüttel, Bruno; McHardy, Alice C; Vorholt, Julia A; Schulze-Lefert, Paul

    2015-12-17

    Roots and leaves of healthy plants host taxonomically structured bacterial assemblies, and members of these communities contribute to plant growth and health. We established Arabidopsis leaf- and root-derived microbiota culture collections representing the majority of bacterial species that are reproducibly detectable by culture-independent community sequencing. We found an extensive taxonomic overlap between the leaf and root microbiota. Genome drafts of 400 isolates revealed a large overlap of genome-encoded functional capabilities between leaf- and root-derived bacteria with few significant differences at the level of individual functional categories. Using defined bacterial communities and a gnotobiotic Arabidopsis plant system we show that the isolates form assemblies resembling natural microbiota on their cognate host organs, but are also capable of ectopic leaf or root colonization. While this raises the possibility of reciprocal relocation between root and leaf microbiota members, genome information and recolonization experiments also provide evidence for microbiota specialization to their respective niche. PMID:26633631

  18. Programming of Plant Leaf Senescence with Temporal and Inter-Organellar Coordination of Transcriptome in Arabidopsis1[OPEN

    PubMed Central

    Koo, Hee Jung; Kim, Jeongsik; Jeong, Hyobin; Yang, Jin Ok; Lee, Il Hwan; Jun, Ji Hyung; Choi, Seung Hee; Park, Su Jin; Kang, Byeongsoo; Kim, You Wang; Phee, Bong-Kwan; Kim, Jin Hee; Seo, Chaehwa; Park, Charny; Kim, Sang Cheol; Park, Seongjin; Lee, Byungwook; Lee, Sanghyuk; Hwang, Daehee; Lim, Pyung Ok

    2016-01-01

    Plant leaves, harvesting light energy and fixing CO2, are a major source of foods on the earth. Leaves undergo developmental and physiological shifts during their lifespan, ending with senescence and death. We characterized the key regulatory features of the leaf transcriptome during aging by analyzing total- and small-RNA transcriptomes throughout the lifespan of Arabidopsis (Arabidopsis thaliana) leaves at multidimensions, including age, RNA-type, and organelle. Intriguingly, senescing leaves showed more coordinated temporal changes in transcriptomes than growing leaves, with sophisticated regulatory networks comprising transcription factors and diverse small regulatory RNAs. The chloroplast transcriptome, but not the mitochondrial transcriptome, showed major changes during leaf aging, with a strongly shared expression pattern of nuclear transcripts encoding chloroplast-targeted proteins. Thus, unlike animal aging, leaf senescence proceeds with tight temporal and distinct interorganellar coordination of various transcriptomes that would be critical for the highly regulated degeneration and nutrient recycling contributing to plant fitness and productivity. PMID:26966169

  19. Inferring the Brassica rapa Interactome Using Protein-Protein Interaction Data from Arabidopsis thaliana.

    PubMed

    Yang, Jianhua; Osman, Kim; Iqbal, Mudassar; Stekel, Dov J; Luo, Zewei; Armstrong, Susan J; Franklin, F Chris H

    2012-01-01

    Following successful completion of the Brassica rapa sequencing project, the next step is to investigate functions of individual genes/proteins. For Arabidopsis thaliana, large amounts of protein-protein interaction (PPI) data are available from the major PPI databases (DBs). It is known that Brassica crop species are closely related to A. thaliana. This provides an opportunity to infer the B. rapa interactome using PPI data available from A. thaliana. In this paper, we present an inferred B. rapa interactome that is based on the A. thaliana PPI data from two resources: (i) A. thaliana PPI data from three major DBs, BioGRID, IntAct, and TAIR. (ii) ortholog-based A. thaliana PPI predictions. Linking between B. rapa and A. thaliana was accomplished in three complementary ways: (i) ortholog predictions, (ii) identification of gene duplication based on synteny and collinearity, and (iii) BLAST sequence similarity search. A complementary approach was also applied, which used known/predicted domain-domain interaction data. Specifically, since the two species are closely related, we used PPI data from A. thaliana to predict interacting domains that might be conserved between the two species. The predicted interactome was investigated for the component that contains known A. thaliana meiotic proteins to demonstrate its usability. PMID:23293649

  20. Inferring the Brassica rapa Interactome Using Protein–Protein Interaction Data from Arabidopsis thaliana

    PubMed Central

    Yang, Jianhua; Osman, Kim; Iqbal, Mudassar; Stekel, Dov J.; Luo, Zewei; Armstrong, Susan J.; Franklin, F. Chris H.

    2013-01-01

    Following successful completion of the Brassica rapa sequencing project, the next step is to investigate functions of individual genes/proteins. For Arabidopsis thaliana, large amounts of protein–protein interaction (PPI) data are available from the major PPI databases (DBs). It is known that Brassica crop species are closely related to A. thaliana. This provides an opportunity to infer the B. rapa interactome using PPI data available from A. thaliana. In this paper, we present an inferred B. rapa interactome that is based on the A. thaliana PPI data from two resources: (i) A. thaliana PPI data from three major DBs, BioGRID, IntAct, and TAIR. (ii) ortholog-based A. thaliana PPI predictions. Linking between B. rapa and A. thaliana was accomplished in three complementary ways: (i) ortholog predictions, (ii) identification of gene duplication based on synteny and collinearity, and (iii) BLAST sequence similarity search. A complementary approach was also applied, which used known/predicted domain–domain interaction data. Specifically, since the two species are closely related, we used PPI data from A. thaliana to predict interacting domains that might be conserved between the two species. The predicted interactome was investigated for the component that contains known A. thaliana meiotic proteins to demonstrate its usability. PMID:23293649

  1. Phenotypic and genetic characterization of resistance in Arabidopsis thaliana to the oomycete pathogen Phytophthora parasitica

    PubMed Central

    Meng, Yuling; Huang, Yihua; Wang, Qinhu; Wen, Qujiang; Jia, Jinbu; Zhang, Qiang; Huang, Guiyan; Quan, Junli; Shan, Weixing

    2015-01-01

    The interaction between Arabidopsis thaliana and the oomycete pathogen Phytophthora parasitica emerges as a model for exploring the molecular basis and evolution of recognition and host defense. Phenotypic variation and genetic analysis is essential to dissect the underlying mechanisms in plant–oomycete interaction. In this study, the reaction phenotypes of 28 A. thaliana accessions to P. parasitica strain Pp016 were examined using detached leaf infection assay. The results showed the presence of four distinct groups based on host response and disease development. Of all the accessions examined, Zurich (Zu-1) is highly resistant to P. parasitica. Microscopic characterization showed that rapid and severe hypersensitive response at the primary infection epidermal cells is associated with disease resistance. Furthermore, Zu-1 is resistant to a set of 20 diverse P. parasitica strains, which were collected from different host plants and exhibited differential specificities on a set of tobacco cultivars. However, Zu-1 is susceptible to P. parasitica when the root is inoculated, suggesting differential expression of associated resistance genes in the root and foliar tissues. Genetic analysis by crossing Zu-1 and the susceptible accession Landsberg (Ler) showed that the resistance in Zu-1 to P. parasitica is semi-dominant, as shown by infection assays of F1 progenies, and is likely conferred by a single locus, defined as RPPA1Zu-1 (for Resistance to P. parasitica 1), as shown by analysis of F2 segregating populations. By employing specific-locus amplified fragment sequencing (SLAF-seq) strategy to identify molecular markers potentially linked to the locus, the strongest associated region was determined to be located between 7.1 and 11.2 Mb in chromosome IV. The future cloning of RPPA1Zu-1 locus will facilitate improved understanding of plant broad-spectrum disease resistance to oomycete pathogens. PMID:26074940

  2. Investigation of the effect of phosphogypsum amendment on two Arabidopsis thaliana ecotype growth and development.

    PubMed

    Ayadi, Amal; Chorriba, Amal; Fourati, Amine; Gargouri-Bouzid, Radhia

    2015-01-01

    The production of phosphoric acid from natural phosphate rock leads to an industrial waste called phosphogypsum (PG). About 5 tons of PG are generated per ton of phosphoric acid produced. This acidic waste (pH 2.2) is mostly disposed of by dumping into large stockpiles close to fertilizer production units, where they occupy large land areas that can cause serious environmental damages. Several attempts were made to test PG valorization via soil amendment because of its phosphate, sulphate and calcium content. The aim of the this study was to evaluate the potential use of PG as phosphate amendment in soil using two wild-type Arabidopsis thaliana ecotypes (Wassilewskija and Colombia) as model plants. Plants were grown in a greenhouse for 30 days, on substrates containing various PG concentrations (0%, 15%, 25%, 40% and 50%). The growth rate and physiological parameters (fresh weight, phosphate and chlorophyll content) were determined. The data revealed that 15% PG did not alter plant survival and leaf's dry weight, and the inorganic phosphate (Pi) uptake by plant seemed to be efficient. However, some alterations in Chlorophyll a/Chlorophyll b ratio were noticed. Higher PG concentrations (40 and 50% PG) exhibited an enhanced negative effect on plant growth, survival and Pi uptake. These inhibitory effects of the substrates may be related to the acidity of the medium in addition to its Cd content. PMID:25495660

  3. Mitochondrial Dihydrolipoyl Dehydrogenase Activity Shapes Photosynthesis and Photorespiration of Arabidopsis thaliana

    PubMed Central

    Timm, Stefan; Wittmiß, Maria; Gamlien, Sabine; Ewald, Ralph; Florian, Alexandra; Frank, Marcus; Wirtz, Markus; Hell, Rüdiger; Fernie, Alisdair R.; Bauwe, Hermann

    2015-01-01

    Mitochondrial dihydrolipoyl dehydrogenase (mtLPD; L-protein) is an integral component of several multienzyme systems involved in the tricarboxylic acid (TCA) cycle, photorespiration, and the degradation of branched-chain α-ketoacids. The majority of the mtLPD present in photosynthesizing tissue is used for glycine decarboxylase (GDC), necessary for the high-flux photorespiratory glycine-into-serine conversion. We previously suggested that GDC activity could be a signal in a regulatory network that adjusts carbon flux through the Calvin-Benson cycle in response to photorespiration. Here, we show that elevated GDC L-protein activity significantly alters several diagnostic parameters of cellular metabolism and leaf gas exchange in Arabidopsis thaliana. Overexpressor lines displayed markedly decreased steady state contents of TCA cycle and photorespiratory intermediates as well as elevated NAD(P)+-to-NAD(P)H ratios. Additionally, increased rates of CO2 assimilation, photorespiration, and plant growth were observed. Intriguingly, however, day respiration rates remained unaffected. By contrast, respiration was enhanced in the first half of the dark phase but depressed in the second. We also observed enhanced sucrose biosynthesis in the light in combination with a lower diel magnitude of starch accumulation and breakdown. These data thus substantiate our prior hypothesis that facilitating flux through the photorespiratory pathway stimulates photosynthetic CO2 assimilation in the Calvin-Benson cycle. They furthermore suggest that this regulation is, at least in part, dependent on increased light-capture/use efficiency. PMID:26116608

  4. Cadmium localization and quantification in the plant Arabidopsis thaliana using micro-PIXE

    NASA Astrophysics Data System (ADS)

    Ager, F. J.; Ynsa, M. D.; Domínguez-Solís, J. R.; Gotor, C.; Respaldiza, M. A.; Romero, L. C.

    2002-04-01

    Remediation of metal-contaminated soils and waters poses a challenging problem due to its implications in the environment and the human health. The use of metal-accumulating plants to remove toxic metals, including Cd, from soil and aqueous streams has been proposed as a possible solution to this problem. The process of using plants for environmental restoration is termed phytoremediation. Cd is a particularly favourable target metal for this technology because it is readily transported and accumulated in the shoots of several plant species. This paper investigates the sites of metal localization within Arabidopsis thaliana leaves, when plants are grown in a cadmium-rich environment, by making use of nuclear microscopy techniques. Micro-PIXE, RBS and SEM analyses were performed on the scanning proton microprobe at the CNA in Seville (Spain), showing that cadmium is sequestered within the trichomes on the leaf surface. Additionally, regular PIXE analyses were performed on samples prepared by an acid digestion method in order to assess the metal accumulation of such plants.

  5. Effect of light quality and vernalization on late-flowering mutants of Arabidopsis thaliana

    SciTech Connect

    Martinez-Zapater, J.M. ); Somerville, C.R. )

    1990-03-01

    We have analyzed the response to vernalization and light quality of six classes of late-flowering mutants (fb, fca, fe, fg, ft, and fy) previously isolated following mutagenesis of the early Landsberg race of Arabidopsis thaliana (L.) Heynh. When grown in continuous fluorescent illumination, four mutants (fca, fe, ft, and fy) and the Landsberg wild type exhibited a reduction in both flowering time and leaf number following 6 weeks of vernalization. A significant decrease in flowering time was also observed for all the mutants and the wild type when constant fluorescent illumination was supplemented with irradiation enriched in the red and far red regions of the spectrum. In the most extreme case, the late-flowering phenotype of the fca mutant was completely suppressed by vernalization, suggesting that this mutation has a direct effect on flowering. The fe and fy mutants also showed a more pronounced response than wild type to both vernalization and incandescent supplementation. The ft mutant showed a similar response to that of the wild type. The fb and fg mutants were substantially less sensitive to these treatments. These results are interpreted in the context of a multifactorial pathway for induction of flowering, in which the various mutations affect different steps of the pathway.

  6. Modification of starch metabolism in transgenic Arabidopsis thaliana increases plant biomass and triples oilseed production.

    PubMed

    Liu, Fushan; Zhao, Qianru; Mano, Noel; Ahmed, Zaheer; Nitschke, Felix; Cai, Yinqqi; Chapman, Kent D; Steup, Martin; Tetlow, Ian J; Emes, Michael J

    2016-03-01

    We have identified a novel means to achieve substantially increased vegetative biomass and oilseed production in the model plant Arabidopsis thaliana. Endogenous isoforms of starch branching enzyme (SBE) were substituted by either one of the endosperm-expressed maize (Zea mays L.) branching isozymes, ZmSBEI or ZmSBEIIb. Transformants were compared with the starch-free background and with the wild-type plants. Each of the maize-derived SBEs restored starch biosynthesis but both morphology and structure of starch particles were altered. Altered starch metabolism in the transformants is associated with enhanced biomass formation and more-than-trebled oilseed production while maintaining seed oil quality. Enhanced oilseed production is primarily due to an increased number of siliques per plant whereas oil content and seed number per silique are essentially unchanged or even modestly decreased. Introduction of cereal starch branching isozymes into oilseed plants represents a potentially useful strategy to increase biomass and oilseed production in related crops and manipulate the structure and properties of leaf starch. PMID:26285603

  7. Mitochondrial Dihydrolipoyl Dehydrogenase Activity Shapes Photosynthesis and Photorespiration of Arabidopsis thaliana.

    PubMed

    Timm, Stefan; Wittmiß, Maria; Gamlien, Sabine; Ewald, Ralph; Florian, Alexandra; Frank, Marcus; Wirtz, Markus; Hell, Rüdiger; Fernie, Alisdair R; Bauwe, Hermann

    2015-07-01

    Mitochondrial dihydrolipoyl dehydrogenase (mtLPD; L-protein) is an integral component of several multienzyme systems involved in the tricarboxylic acid (TCA) cycle, photorespiration, and the degradation of branched-chain α-ketoacids. The majority of the mtLPD present in photosynthesizing tissue is used for glycine decarboxylase (GDC), necessary for the high-flux photorespiratory glycine-into-serine conversion. We previously suggested that GDC activity could be a signal in a regulatory network that adjusts carbon flux through the Calvin-Benson cycle in response to photorespiration. Here, we show that elevated GDC L-protein activity significantly alters several diagnostic parameters of cellular metabolism and leaf gas exchange in Arabidopsis thaliana. Overexpressor lines displayed markedly decreased steady state contents of TCA cycle and photorespiratory intermediates as well as elevated NAD(P)(+)-to-NAD(P)H ratios. Additionally, increased rates of CO2 assimilation, photorespiration, and plant growth were observed. Intriguingly, however, day respiration rates remained unaffected. By contrast, respiration was enhanced in the first half of the dark phase but depressed in the second. We also observed enhanced sucrose biosynthesis in the light in combination with a lower diel magnitude of starch accumulation and breakdown. These data thus substantiate our prior hypothesis that facilitating flux through the photorespiratory pathway stimulates photosynthetic CO2 assimilation in the Calvin-Benson cycle. They furthermore suggest that this regulation is, at least in part, dependent on increased light-capture/use efficiency. PMID:26116608

  8. Characterization of Arabidopsis thaliana GCN2 kinase roles in seed germination and plant development.

    PubMed

    Liu, Xiaoyu; Merchant, Azim; Rockett, Kristin S; McCormack, Maggie; Pajerowska-Mukhtar, Karolina M

    2015-01-01

    Eukaryotic GCN2 (general control nonderepressible 2) is a serine/threonine protein kinase that plays an essential role in modulating amino acid metabolism in response to nutrient deprivation. A wide spectrum of GCN2 functions in yeast and mammals has been characterized that spans from responses to amino acid deficiency, development, differentiation and proper functions of mammalian organs to organism's life span, tumor cell survival and immune responses. Here we demonstrate that Arabidopsis thaliana GCN2 (AtGCN2) plays crucial roles in plant growth and development. We present evidence that AtGCN2 negatively regulates seed germination under diverse environmental conditions. Our genetic data supported the notion that AtGCN2 is required for leaf morphology and normal cellular physiology by controlling chlorophyll contents. Our gene expression analyses revealed that AtGCN2 negatively regulates several transcription factor genes that play important roles in plant gibberellic acid-related crosstalk. We concluded that AtGCN2 plays pivotal roles in various cellular processes essential for normal growth and development, hence expanding the functions of this general regulator beyond being merely a stress player. PMID:25912940

  9. Initiation patterns of flower and floral organ development in Arabidopsis thaliana.

    PubMed

    Bossinger, G; Smyth, D R

    1996-04-01

    Sector boundary analysis has been used to deduce the number and orientation of cells initiating flower and floral organ development in Arabidopsis thaliana. Sectors were produced in transgenic plants carrying the Ac transposon from maize inserted between the constitutive 35S promoter and the GUS reporter gene. Excision of the transposon results in a blue-staining sector. Plants were chosen in which an early arising sector passed from vegetative regions into the inflorescence and through a mature flower. The range of sector boundary positions seen in mature flowers indicated that flower primordia usually arise from a group of four cells on the inflorescence flank. The radial axes of the mature flower are apparently set by these cells, supporting the concept that they act as a structural template. Floral organs show two patterns of initiation, a leaf-like pattern with eight cells in a row (sepals and carpels), or a shoot-like pattern with four cells in a block (stamens). The petal initiation pattern involved too few cells to allow assignment. The numbers of initiating cells were close to those seen when organ growth commenced in each case, indicating that earlier specification of floral organ development does not occur. By examining sector boundaries in homeotic mutant flowers in which second whorl organs develop as sepal-like organs rather than petals, we have shown that their pattern of origin is position dependent rather than identity dependent. PMID:8620836

  10. Metabolic and diffusional limitations of photosynthesis in fluctuating irradiance in Arabidopsis thaliana

    PubMed Central

    Kaiser, Elias; Morales, Alejandro; Harbinson, Jeremy; Heuvelink, Ep; Prinzenberg, Aina E.; Marcelis, Leo F. M.

    2016-01-01

    A better understanding of the metabolic and diffusional limitations of photosynthesis in fluctuating irradiance can help identify targets for improving crop yields. We used different genotypes of Arabidopsis thaliana to characterise the importance of Rubisco activase (Rca), stomatal conductance (gs), non-photochemical quenching of chlorophyll fluorescence (NPQ) and sucrose phosphate synthase (SPS) on photosynthesis in fluctuating irradiance. Leaf gas exchange and chlorophyll fluorescence were measured in leaves exposed to stepwise increases and decreases in irradiance. rwt43, which has a constitutively active Rubisco enzyme in different irradiance intensities (except in darkness), showed faster increases than the wildtype, Colombia-0, in photosynthesis rates after step increases in irradiance. rca-2, having decreased Rca concentration, showed lower rates of increase. In aba2-1, high gs increased the rate of change after stepwise irradiance increases, while in C24, low gs tended to decrease it. Differences in rates of change between Colombia-0 and plants with low levels of NPQ (npq1-2, npq4-1) or SPS (spsa1) were negligible. In Colombia-0, the regulation of Rubisco activation and of gs were therefore limiting for photosynthesis in fluctuating irradiance, while levels of NPQ or SPS were not. This suggests Rca and gs as targets for improvement of photosynthesis of plants in fluctuating irradiance. PMID:27502328