Sample records for arabidopsis thaliana leaf

  1. Lunar gravity affects leaf movement of Arabidopsis thaliana in the International Space Station.

    PubMed

    Fisahn, Joachim; Klingelé, Emile; Barlow, Peter

    2015-06-01

    Cyclic leaf ascent and descent occur in synchrony and phase congruence with the lunisolar tidal force under a broad range of conditions. Digitized records of the vertical leaf movements of Arabidopsis thaliana were collected under space flight conditions in the International Space Station (ISS). Oscillations of leaf movements with periods of 45 and 90 min were found under light-adapted conditions, whereas in darkness, the periods were 45, 90, and 135 min. To demonstrate the close relationship between these oscillations and cyclical variations of the lunisolar gravitational force, we estimated the oscillations of the in-orbit lunisolar tide as they apply to the ISS, with the aid of the Etide software application. In general, in-orbit lunisolar gravitational profiles exhibited a periodicity of 45 min. Alignment of these in-orbit oscillations with the oscillations of Arabidopsis leaf movement revealed high degrees of synchrony and a congruence of phase. These data corroborate previous results which suggested a correlative relationship and a possible causal link between leaf movement rhythms obtained on ground and the rhythmic variation of the lunisolar tidal force.

  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.

  3. Leaf hydraulic conductance varies with vein anatomy across Arabidopsis thaliana wild-type and leaf vein mutants.

    PubMed

    Caringella, Marissa A; Bongers, Franca J; Sack, Lawren

    2015-12-01

    Leaf venation is diverse across plant species and has practical applications from paleobotany to modern agriculture. However, the impact of vein traits on plant performance has not yet been tested in a model system such as Arabidopsis thaliana. Previous studies analysed cotyledons of A. thaliana vein mutants and identified visible differences in their vein systems from the wild type (WT). We measured leaf hydraulic conductance (Kleaf ), vein traits, and xylem and mesophyll anatomy for A. thaliana WT (Col-0) and four vein mutants (dot3-111 and dot3-134, and cvp1-3 and cvp2-1). Mutant true leaves did not possess the qualitative venation anomalies previously shown in the cotyledons, but varied quantitatively in vein traits and leaf anatomy across genotypes. The WT had significantly higher mean Kleaf . Across all genotypes, there was a strong correlation of Kleaf with traits related to hydraulic conductance across the bundle sheath, as influenced by the number and radial diameter of bundle sheath cells and vein length per area. These findings support the hypothesis that vein traits influence Kleaf , indicating the usefulness of this mutant system for testing theory that was primarily established comparatively across species, and supports a strong role for the bundle sheath in influencing Kleaf . © 2015 John Wiley & Sons Ltd.

  4. 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

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

    DOE PAGES

    Weraduwage, Sarathi M.; Chen, Jin; Anozie, Fransisca C.; ...

    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

  6. 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.

  7. 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.

  8. Arabidopsis thaliana alpha1,2-glucosyltransferase (ALG10) is required for efficient N-glycosylation and leaf growth

    PubMed Central

    Farid, Akhlaq; Pabst, Martin; Schoberer, Jennifer; Altmann, Friedrich; Glössl, Josef; Strasser, Richard

    2011-01-01

    Assembly of the dolichol-linked oligosaccharide precursor (Glc3Man9GlcNAc2) is highly conserved among eukaryotes. In contrast to yeast and mammals, little is known about the biosynthesis of dolichol-linked oligosaccharides and the transfer to asparagine residues of nascent polypeptides in plants. To understand the biological function of these processes in plants we characterized the Arabidopsis thaliana homolog of yeast ALG10, the α1,2-glucosyltransferase that transfers the terminal glucose residue to the lipid-linked precursor. Expression of an Arabidopsis ALG10–GFP fusion protein in Nicotiana benthamiana leaf epidermal cells revealed a reticular distribution pattern resembling endoplasmic reticulum (ER) localization. Analysis of lipid-linked oligosaccharides showed that Arabidopsis ALG10 can complement the yeast Δalg10 mutant strain. A homozygous Arabidopsis T-DNA insertion mutant (alg10-1) accumulated mainly lipid-linked Glc2Man9GlcNAc2 and displayed a severe protein underglycosylation defect. Phenotypic analysis of alg10-1 showed that mutant plants have altered leaf size when grown in soil. Moreover, the inactivation of ALG10 in Arabidopsis resulted in the activation of the unfolded protein response, increased salt sensitivity and suppression of the phenotype of α-glucosidase I-deficient plants. In summary, these data show that Arabidopsis ALG10 is an ER-resident α1,2-glucosyltransferase that is required for lipid-linked oligosaccharide biosynthesis and subsequently for normal leaf development and abiotic stress response. PMID:21707802

  9. Leaf Segmentation and Tracking in Arabidopsis thaliana Combined to an Organ-Scale Plant Model for Genotypic Differentiation

    PubMed Central

    Viaud, Gautier; Loudet, Olivier; Cournède, Paul-Henry

    2017-01-01

    A promising method for characterizing the phenotype of a plant as an interaction between its genotype and its environment is to use refined organ-scale plant growth models that use the observation of architectural traits, such as leaf area, containing a lot of information on the whole history of the functioning of the plant. The Phenoscope, a high-throughput automated platform, allowed the acquisition of zenithal images of Arabidopsis thaliana over twenty one days for 4 different genotypes. A novel image processing algorithm involving both segmentation and tracking of the plant leaves allows to extract areas of the latter. First, all the images in the series are segmented independently using a watershed-based approach. A second step based on ellipsoid-shaped leaves is then applied on the segments found to refine the segmentation. Taking into account all the segments at every time, the whole history of each leaf is reconstructed by choosing recursively through time the most probable segment achieving the best score, computed using some characteristics of the segment such as its orientation, its distance to the plant mass center and its area. These results are compared to manually extracted segments, showing a very good accordance in leaf rank and that they therefore provide low-biased data in large quantity for leaf areas. Such data can therefore be exploited to design an organ-scale plant model adapted from the existing GreenLab model for A. thaliana and subsequently parameterize it. This calibration of the model parameters should pave the way for differentiation between the Arabidopsis genotypes. PMID:28123392

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

    USDA-ARS?s Scientific Manuscript database

    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 ...

  11. Protein Degradation Rate in Arabidopsis thaliana Leaf Growth and Development[OPEN

    PubMed Central

    Nelson, Clark J.; Castleden, Ian

    2017-01-01

    We applied 15N labeling approaches to leaves of the Arabidopsis thaliana rosette to characterize their protein degradation rate and understand its determinants. The progressive labeling of new peptides with 15N and measuring the decrease in the abundance of >60,000 existing peptides over time allowed us to define the degradation rate of 1228 proteins in vivo. We show that Arabidopsis protein half-lives vary from several hours to several months based on the exponential constant of the decay rate for each protein. This rate was calculated from the relative isotope abundance of each peptide and the fold change in protein abundance during growth. Protein complex membership and specific protein domains were found to be strong predictors of degradation rate, while N-end amino acid, hydrophobicity, or aggregation propensity of proteins were not. We discovered rapidly degrading subunits in a variety of protein complexes in plastids and identified the set of plant proteins whose degradation rate changed in different leaves of the rosette and correlated with leaf growth rate. From this information, we have calculated the protein turnover energy costs in different leaves and their key determinants within the proteome. PMID:28138016

  12. Alteration in Auxin Homeostasis and Signaling by Overexpression Of PINOID Kinase Causes Leaf Growth Defects in Arabidopsis thaliana

    PubMed Central

    Saini, Kumud; Markakis, Marios N.; Zdanio, Malgorzata; Balcerowicz, Daria M.; Beeckman, Tom; De Veylder, Lieven; Prinsen, Els; Beemster, Gerrit T. S.; Vissenberg, Kris

    2017-01-01

    In plants many developmental processes are regulated by auxin and its directional transport. PINOID (PID) kinase helps to regulate this transport by influencing polar recruitment of PIN efflux proteins on the cellular membranes. We investigated how altered auxin levels affect leaf growth in Arabidopsis thaliana. Arabidopsis mutants and transgenic plants with altered PID expression levels were used to study the effect on auxin distribution and leaf development. Single knockouts showed small pleiotropic growth defects. Contrastingly, several leaf phenotypes related to changes in auxin concentrations and transcriptional activity were observed in PID overexpression (PIDOE) lines. Unlike in the knockout lines, the leaves of PIDOE lines showed an elevation in total indole-3-acetic acid (IAA). Accordingly, enhanced DR5-visualized auxin responses were detected, especially along the leaf margins. Kinematic analysis revealed that ectopic expression of PID negatively affects cell proliferation and expansion rates, yielding reduced cell numbers and small-sized cells in the PIDOE leaves. We used PIDOE lines as a tool to study auxin dose effects on leaf development and demonstrate that auxin, above a certain threshold, has a negative affect on leaf growth. RNA sequencing further showed how subtle PIDOE-related changes in auxin levels lead to transcriptional reprogramming of cellular processes. PMID:28659952

  13. 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. © 2014 John Wiley & Sons Ltd.

  14. 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.

  15. 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

  16. 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

  17. F-Box Protein FBX92 Affects Leaf Size in Arabidopsis thaliana

    PubMed Central

    Baute, Joke; Polyn, Stefanie; De Block, Jolien; Blomme, Jonas; Van Lijsebettens, Mieke

    2017-01-01

    F-box proteins are part of one of the largest families of regulatory proteins that play important roles in protein degradation. In plants, F-box proteins are functionally very diverse, and only a small subset has been characterized in detail. Here, we identified a novel F-box protein FBX92 as a repressor of leaf growth in Arabidopsis. Overexpression of AtFBX92 resulted in plants with smaller leaves than the wild type, whereas plants with reduced levels of AtFBX92 showed, in contrast, increased leaf growth by stimulating cell proliferation. Detailed cellular analysis suggested that AtFBX92 specifically affects the rate of cell division during early leaf development. This is supported by the increased expression levels of several cell cycle genes in plants with reduced AtFBX92 levels. Surprisingly, overexpression of the maize homologous gene ZmFBX92 in maize had no effect on plant growth, whereas ectopic expression in Arabidopsis increased leaf growth. Expression of a truncated form of AtFBX92 showed that the contrasting effects of ZmFBX92 and AtFBX92 gain of function in Arabidopsis are due to the absence of the F-box-associated domain in the ZmFBX92 gene. Our work reveals an additional player in the complex network that determines leaf size and lays the foundation for identifying putative substrates. PMID:28340173

  18. Structural assessment of the impact of environmental constraints on Arabidopsis thaliana leaf growth: a 3D approach.

    PubMed

    Wuyts, Nathalie; Massonnet, Catherine; Dauzat, Myriam; Granier, Christine

    2012-09-01

    Light and soil water content affect leaf surface area expansion through modifications in epidermal cell numbers and area, while effects on leaf thickness and mesophyll cell volumes are far less documented. Here, three-dimensional imaging was applied in a study of Arabidopsis thaliana leaf growth to determine leaf thickness and the cellular organization of mesophyll tissues under moderate soil water deficit and two cumulative light conditions. In contrast to surface area, thickness was highly conserved in response to water deficit under both low and high cumulative light regimes. Unlike epidermal and palisade mesophyll tissues, no reductions in cell number were observed in the spongy mesophyll; cells had rather changed in volume and shape. Furthermore, leaf features of a selection of genotypes affected in leaf functioning were analysed. The low-starch mutant pgm had very thick leaves because of unusually large palisade mesophyll cells, together with high levels of photosynthesis and stomatal conductance. By means of an open stomata mutant and a 9-cis-epoxycarotenoid dioxygenase overexpressor, it was shown that stomatal conductance does not necessarily have a major impact on leaf dimensions and cellular organization, pointing to additional mechanisms for the control of CO(2) diffusion under high and low stomatal conductance, respectively. © 2012 Blackwell Publishing Ltd.

  19. F-Box Protein FBX92 Affects Leaf Size in Arabidopsis thaliana.

    PubMed

    Baute, Joke; Polyn, Stefanie; De Block, Jolien; Blomme, Jonas; Van Lijsebettens, Mieke; Inzé, Dirk

    2017-05-01

    F-box proteins are part of one of the largest families of regulatory proteins that play important roles in protein degradation. In plants, F-box proteins are functionally very diverse, and only a small subset has been characterized in detail. Here, we identified a novel F-box protein FBX92 as a repressor of leaf growth in Arabidopsis. Overexpression of AtFBX92 resulted in plants with smaller leaves than the wild type, whereas plants with reduced levels of AtFBX92 showed, in contrast, increased leaf growth by stimulating cell proliferation. Detailed cellular analysis suggested that AtFBX92 specifically affects the rate of cell division during early leaf development. This is supported by the increased expression levels of several cell cycle genes in plants with reduced AtFBX92 levels. Surprisingly, overexpression of the maize homologous gene ZmFBX92 in maize had no effect on plant growth, whereas ectopic expression in Arabidopsis increased leaf growth. Expression of a truncated form of AtFBX92 showed that the contrasting effects of ZmFBX92 and AtFBX92 gain of function in Arabidopsis are due to the absence of the F-box-associated domain in the ZmFBX92 gene. Our work reveals an additional player in the complex network that determines leaf size and lays the foundation for identifying putative substrates. © The Author 2017. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.

  20. Quantitative trait loci controlling leaf venation in Arabidopsis.

    PubMed

    Rishmawi, Louai; Bühler, Jonas; Jaegle, Benjamin; Hülskamp, Martin; Koornneef, Maarten

    2017-08-01

    Leaf veins provide the mechanical support and are responsible for the transport of nutrients and water to the plant. High vein density is a prerequisite for plants to have C4 photosynthesis. We investigated the genetic variation and genetic architecture of leaf venation traits within the species Arabidopsis thaliana using natural variation. Leaf venation traits, including leaf vein density (LVD) were analysed in 66 worldwide accessions and 399 lines of the multi-parent advanced generation intercross population. It was shown that there is no correlation between LVD and photosynthesis parameters within A. thaliana. Association mapping was performed for LVD and identified 16 and 17 putative quantitative trait loci (QTLs) in the multi-parent advanced generation intercross and worldwide sets, respectively. There was no overlap between the identified QTLs suggesting that many genes can affect the traits. In addition, linkage mapping was performed using two biparental recombinant inbred line populations. Combining linkage and association mapping revealed seven candidate genes. For one of the candidate genes, RCI2c, we demonstrated its function in leaf venation patterning. © 2017 John Wiley & Sons Ltd.

  1. 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

  2. Genome-wide association study of Arabidopsis thaliana leaf microbial community.

    PubMed

    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

    2014-11-10

    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 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 microbe 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.

  3. AtHMA4 Drives Natural Variation in Leaf Zn Concentration of Arabidopsis thaliana

    PubMed Central

    Chen, Zi-Ru; Kuang, Lu; Gao, Yi-Qun; Wang, Ya-Ling; Salt, David E.; Chao, Dai-Yin

    2018-01-01

    Zinc (Zn) is an essential element for plant growth and development, and Zn derived from crop plants in the diet is also important for human health. Here, we report that genetic variation in Heavy Metal-ATPase 4 (HMA4) controls natural variation in leaf Zn content. Investigation of the natural variation in leaf Zn content in a world-wide collection of 349 Arabidopsis thaliana wild collected accessions identified two accessions, Van-0 and Fab-2, which accumulate significantly lower Zn when compared with Col-0. Both quantitative trait loci (QTL) analysis and bulked segregant analysis (BSA) identified HMA4 as a strong candidate accounting for this variation in leaf Zn concentration. Genetic complementation experiments confirmed this hypothesis. Sequence analysis revealed that a 1-bp deletion in the third exon of HMA4 from Fab-2 is responsible for the lose of function of HMA4 driving the low Zn observed in Fab-2. Unlike in Fab-2 polymorphisms in the promoter region were found to be responsible for the weak function of HMA4 in Van-0. This is supported by both an expression analysis of HMA4 in Van-0 and through a series of T-DNA insertion mutants which generate truncated HMA4 promoters in the Col-0 background. In addition, we also observed that Fab-2, Van-0 and the hma4-2 null mutant in the Col-0 background show enhanced resistance to a combination of high Zn and high Cd in the growth medium, raising the possibility that variation at HMA4 may play a role in environmental adaptation. PMID:29545819

  4. AtHMA4 Drives Natural Variation in Leaf Zn Concentration of Arabidopsis thaliana.

    PubMed

    Chen, Zi-Ru; Kuang, Lu; Gao, Yi-Qun; Wang, Ya-Ling; Salt, David E; Chao, Dai-Yin

    2018-01-01

    Zinc (Zn) is an essential element for plant growth and development, and Zn derived from crop plants in the diet is also important for human health. Here, we report that genetic variation in Heavy Metal-ATPase 4 ( HMA4 ) controls natural variation in leaf Zn content. Investigation of the natural variation in leaf Zn content in a world-wide collection of 349 Arabidopsis thaliana wild collected accessions identified two accessions, Van-0 and Fab-2, which accumulate significantly lower Zn when compared with Col-0. Both quantitative trait loci (QTL) analysis and bulked segregant analysis (BSA) identified HMA4 as a strong candidate accounting for this variation in leaf Zn concentration. Genetic complementation experiments confirmed this hypothesis. Sequence analysis revealed that a 1-bp deletion in the third exon of HMA4 from Fab-2 is responsible for the lose of function of HMA4 driving the low Zn observed in Fab-2. Unlike in Fab-2 polymorphisms in the promoter region were found to be responsible for the weak function of HMA4 in Van-0. This is supported by both an expression analysis of HMA4 in Van-0 and through a series of T-DNA insertion mutants which generate truncated HMA4 promoters in the Col-0 background. In addition, we also observed that Fab-2, Van-0 and the hma4-2 null mutant in the Col-0 background show enhanced resistance to a combination of high Zn and high Cd in the growth medium, raising the possibility that variation at HMA4 may play a role in environmental adaptation.

  5. Differential growth of pavement cells of Arabidopsis thaliana leaf epidermis as revealed by microbead labeling.

    PubMed

    Elsner, Joanna; Lipowczan, Marcin; Kwiatkowska, Dorota

    2018-02-01

    In numerous vascular plants, pavement cells of the leaf epidermis are shaped like a jigsaw-puzzle piece. Knowledge about the subcellular pattern of growth that accompanies morphogenesis of such a complex shape is crucial for studies of the role of the cytoskeleton, cell wall and phytohormones in plant cell development. Because the detailed growth pattern of the anticlinal and periclinal cell walls remains unknown, our aim was to measure pavement cell growth at a subcellular resolution. Using fluorescent microbeads applied to the surface of the adaxial leaf epidermis of Arabidopsis thaliana as landmarks for growth computation, we directly assessed the growth rates for the outer periclinal and anticlinal cell walls at a subcellular scale. We observed complementary tendencies in the growth pattern of the outer periclinal and anticlinal cell walls. Central portions of periclinal walls were characterized by relatively slow growth, while growth of the other wall portions was heterogeneous. Local growth of the periclinal walls accompanying lobe development after initiation was relatively fast and anisotropic, with maximal extension usually in the direction along the lobe axis. This growth pattern of the periclinal walls was complemented by the extension of the anticlinal walls, which was faster on the lobe sides than at the tips. Growth of the anticlinal and outer periclinal walls of leaf pavement cells is heterogeneous. The growth of the lobes resembles cell elongation via diffuse growth rather than tip growth. © 2018 Botanical Society of America.

  6. Similar Pathogen Targets in Arabidopsis thaliana and Homo sapiens Protein Networks

    DTIC Science & Technology

    2012-09-21

    Similar Pathogen Targets in Arabidopsis thaliana and Homo sapiens Protein Networks Paulo Shakarian1*, J. Kenneth Wickiser2 1 Paulo Shakarian...significantly attacked. Citation: Shakarian P, Wickiser JK (2012) Similar Pathogen Targets in Arabidopsis thaliana and Homo sapiens Protein Networks...to 00-00-2012 4. TITLE AND SUBTITLE Similar Pathogen Targets in Arabidopsis thaliana and Homo sapiens Protein Networks 5a. CONTRACT NUMBER 5b

  7. Activity of Icacinol from Icacina trichantha on Seedling Growth of Oryza sativa and Arabidopsis thaliana.

    PubMed

    Zhao, Ming; Guo, Brian; Onakpa, Michael M; Wong, Tiffany; Wakasa, Kyo; Che, Chun-Tao; Warpeha, Katherine

    2017-12-22

    Broadleaf weeds are very costly for crop growers. Additional herbicidal compounds need to be obtained, especially from natural sources. Extracts of Icacina trichantha were evaluated for responses in germinating seeds and seedlings of rice (Oryza sativa) and Arabidopsis (Arabidopsis thaliana). An ethyl acetate fraction of I. trichantha tuber and a diterpenoid constituent, icacinol (1), were found to have impacts on germination and growth of seedlings. The seed germination inhibitory activity on rice was minimal, but significant on Arabidopsis. While rice indicated some growth delay in leaf expansion in the presence of 1, the effects appeared temporary; chlorophyll and anthocyanins were not significantly altered compared to DMSO controls. Rice seedlings attained biomass similar to DMSO controls, and rice grains per panicle were not significantly different from the DMSO controls. On the other hand, Arabidopsis exhibited damage to leaf expansion, reduced chlorophyll, and increased anthocyanins in aerial portions of the seedlings. Icacinol (1) may be a suitable chemical agent to investigate further for the treatment of eudicot weeds.

  8. NAC transcription factor speedy hyponastic growth regulates flooding-induced leaf movement in Arabidopsis.

    PubMed

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

    2013-12-01

    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.

  9. Piriformospora indica Stimulates Root Metabolism of Arabidopsis thaliana.

    PubMed

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

    2016-07-08

    Piriformospora indica is a root-colonizing fungus, which interacts with a variety of plants including Arabidopsis thaliana. This interaction has been considered as mutualistic leading to growth promotion of the host. So far, only indolic glucosinolates and phytohormones have been identified as key players. In a comprehensive non-targeted metabolite profiling study, we analyzed Arabidopsis thaliana's roots, root exudates, and leaves of inoculated and non-inoculated plants by ultra performance liquid chromatography/electrospray ionization quadrupole-time-of-flight mass spectrometry (UPLC/(ESI)-QTOFMS) and gas chromatography/electron ionization quadrupole mass spectrometry (GC/EI-QMS), and identified further biomarkers. Among them, the concentration of nucleosides, dipeptides, oligolignols, and glucosinolate degradation products was affected in the exudates. In the root profiles, nearly all metabolite levels increased upon co-cultivation, like carbohydrates, organic acids, amino acids, glucosinolates, oligolignols, and flavonoids. In the leaf profiles, we detected by far less significant changes. We only observed an increased concentration of organic acids, carbohydrates, ascorbate, glucosinolates and hydroxycinnamic acids, and a decreased concentration of nitrogen-rich amino acids in inoculated plants. These findings contribute to the understanding of symbiotic interactions between plant roots and fungi of the order of Sebacinales and are a valid source for follow-up mechanistic studies, because these symbioses are particular and clearly different from interactions of roots with mycorrhizal fungi or dark septate endophytes.

  10. Adsorption and inhibition of CuO nanoparticles on Arabidopsis thaliana root

    NASA Astrophysics Data System (ADS)

    Xu, Lina

    2018-02-01

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

  11. Allelopathic Monoterpenes Interfere with Arabidopsis thaliana Cuticular Waxes and Enhance Transpiration

    PubMed Central

    Kussmann, Petra; Knop, Mona; Kriegs, Bettina; Gresens, Frank; Eichert, Thomas; Ulbrich, Andreas; Marx, Friedhelm; Fabricius, Heinz; Goldbach, Heiner; Noga, Georg

    2007-01-01

    Exposure to the allelopathic monoterpenes camphor (100 mg/10 L) and menthol (50 mg/10 L) for 24 h enhanced transpiration of Arabidopsis thaliana fully developed rosette leaves similar to de-waxing. As ascertained by ESEM analyses the leaf surfaces were spotted with platelet like structures which seem to be partly mixed with the lipophilic epicuticular layers. The structures are supposed to contain the condensed monoterpenes, which could be identified by GC. Long term exposure (more than 48 h) to 100 mg/50 mg killed the plants by desiccation, a 24 h exposure caused necrotic spots that became visible one to two days after the treatment. Examinations of the stomatal apertures indicated that monoterpenes induced stomatal opening followed by extreme swelling and a final break down of the protoplasts. Exposure of Arabidopsis thaliana to volatiles of Mentha piperita, Lavandula latifolia and Artemisia camphorata resulted in a dramatic increase of the stomata aperture but swelling of the protoplasts was less exhibited. In contrast to de-waxing, expression of the fatty acid condensing enzyme encoding CER6 gene and de novo synthesis of CER6 protein was not induced after 24 h of exposure to the monoterpenes. The aim of the study was to demonstrate that the lipophilic layers of the leaf surface and the stomata are primary targets of monoterpene allelopathic attack. Enhanced transpiration results from a combination of affected lipophilic wax layers and a disturbed stomata function. PMID:19516993

  12. 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

  13. Gravitropism in leaves of Arabidopsis thaliana (L.) Heynh.

    PubMed

    Mano, Eriko; Horiguchi, Gorou; Tsukaya, Hirokazu

    2006-02-01

    In higher plants, stems and roots show negative and positive gravitropism, respectively. However, current knowledge on the graviresponse of leaves is lacking. In this study, we analyzed the positioning and movement of rosette leaves of Arabidopsis thaliana under light and dark conditions. We found that the radial positioning of rosette leaves was not affected by the direction of gravity under continuous white light. In contrast, when plants were shifted to darkness, the leaves moved upwards, suggesting negative gravitropism. Analysis of the phosphoglucomutase and shoot gravitropism 2-1 mutants revealed that the sedimenting amyloplasts in the leaf petiole are important for gravity perception, as is the case in stems and roots. In addition, our detailed physiological analyses revealed a unique feature of leaf movement after the shift to darkness, i.e. movement could be divided into negative gravitropism and nastic movement. The orientation of rosette leaves is ascribed to a combination of these movements.

  14. Metabolic footprint of epiphytic bacteria on Arabidopsis thaliana leaves

    PubMed Central

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

    2016-01-01

    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

  15. The infective cycle of Cabbage leaf curl virus (CaLCuV) is affected by CRUMPLED LEAF (CRL) gene in Arabidopsis thaliana

    PubMed Central

    Trejo-Saavedra, Diana L; Vielle-Calzada, Jean P; Rivera-Bustamante, Rafael F

    2009-01-01

    Background Geminiviruses are single-stranded DNA viruses that cause serious crop losses worldwide. Successful infection by these pathogens depends extensively on virus-host intermolecular interactions that allow them to express their gene products, to replicate their genomes and to move to adjacent cells and throughout the plant. Results To identify host genes that show an altered regulation in response to Cabbage leaf curl virus (CaLCuV) infection, a screening of transposant Arabidopsis thaliana lines was carried out. Several genes were identified to be virus responsive and one, Crumpled leaf (CRL) gene, was selected for further characterization. CRL was previously reported by Asano et al., (2004) to affect the morphogenesis of all plant organs and the division of plastids. We report here that CRL expression, during CaLCuV infection, shows a short but strong induction at an early stage (3-5 days post inoculation, dpi). To study the role of CRL in CaLCuV infection, CRL over-expressing and silenced transgenic plants were generated. We compared the replication, movement and infectivity of CaLCuV in transgenic and wild type plants. Conclusion Our results showed that CRL over-expressing plants showed an increased susceptibility to CaLCuV infection (as compared to wt plants) whereas CRL-silenced plants, on the contrary, presented a reduced susceptibility to viral infection. The possible role of CRL in the CaLCuV infection cycle is discussed. PMID:19840398

  16. Leaf Responses to Mild Drought Stress in Natural Variants of Arabidopsis1[OPEN

    PubMed Central

    Clauw, Pieter; Coppens, Frederik; De Beuf, Kristof; Dhondt, Stijn; Van Daele, Twiggy; Maleux, Katrien; Storme, Veronique; Clement, Lieven; Gonzalez, Nathalie; Inzé, Dirk

    2015-01-01

    Although the response of plants exposed to severe drought stress has been studied extensively, little is known about how plants adapt their growth under mild drought stress conditions. Here, we analyzed the leaf and rosette growth response of six Arabidopsis (Arabidopsis thaliana) accessions originating from different geographic regions when exposed to mild drought stress. The automated phenotyping platform WIWAM was used to impose stress early during leaf development, when the third leaf emerges from the shoot apical meristem. Analysis of growth-related phenotypes showed differences in leaf development between the accessions. In all six accessions, mild drought stress reduced both leaf pavement cell area and number without affecting the stomatal index. Genome-wide transcriptome analysis (using RNA sequencing) of early developing leaf tissue identified 354 genes differentially expressed under mild drought stress in the six accessions. Our results indicate the existence of a robust response over different genetic backgrounds to mild drought stress in developing leaves. The processes involved in the overall mild drought stress response comprised abscisic acid signaling, proline metabolism, and cell wall adjustments. In addition to these known severe drought-related responses, 87 genes were found to be specific for the response of young developing leaves to mild drought stress. PMID:25604532

  17. 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. © 2015 American Society of Plant Biologists. All Rights Reserved.

  18. Correlative controls of senescence and plant death in Arabidopsis thaliana (Brassicaceae).

    PubMed

    Noodén, L D; Penney, J P

    2001-11-01

    Like most monocarpic plants, longevity of Arabidopsis thaliana plants is controlled by the reproductive structures; however, they appear to work differently from most dicots studied. Neither male- and female-sterility mutations (ms1-1 and bell1, respectively) nor surgical removal of the stems with inflorescences (bolts) at various stages significantly increased the longevity of individual rosette leaves, yet the mutants and treated plants lived 20-50 d longer, measured by the death of the last rosette and/or the last cauline leaf. A series of growth mutations (clv2-4, clv3-2, det3, vam1 enh, and dark green) also increased plant longevity by 20-30 d but did not delay the overall development of the plants. The mutations prolonged plant life through the production of new leaves and stems with inflorescences (bolts) rather than by extending leaf longevity. In growing stems, the newly-formed leaves may induce senescence in the older leaves; however, removal of the younger leaves did not significantly increase the life of the older leaves on the compressed stems of Arabidopsis. Since plants that produce more bolts also live longer, the reproductive load (dry weight) of the bolts did not seem to drive leaf or whole plant senescence here. The developing reproductive structures caused the death of the plant by preventing regeneration of leaves and bolts, which are green and presumably photosynthetic. They also exerted a correlative control (repression) on the development of additional reproductive structures.

  19. 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

  20. 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

  1. Distinct modes of adventitious rooting in Arabidopsis thaliana.

    PubMed

    Correa, L da Rocha; Troleis, J; Mastroberti, A A; Mariath, J E A; Fett-Neto, A G

    2012-01-01

    The literature describes different rooting protocols for Arabidopsis thaliana as models to study adventitious rooting, and results are generally perceived as comparable. However, there is a lack of investigations focusing on the distinct features, advantages and limitations of each method in the study of adventitious rooting with both wild-type (WT) ecotypes and their respective mutants. This investigation was undertaken to evaluate the adventitious rooting process in three different experimental systems, all using A. thaliana, analysing the same rooting parameters after transient exposure to auxin (indole-3-acetic acid) and control conditions: excised leaves, de-rooted plants and etiolated seedlings. The founding tissues and sites of origin of roots differed depending on the system used, whereas all rooting patterns were of the direct type (i.e., without callus formation). None of the systems had an absolute requirement for exogenous auxin, although rooting was enhanced by this phytohormone, with the exception of de-rooted plants, which had adventitious rooting strongly inhibited by exogenous auxin. Root elongation was much favoured in isolated leaves. Auxin-overproducing mutants could not be used in the detached leaf system due to precocious senescence; in the de-rooted plant system, these mutants had a WT-like rooting response, whereas the expression of the 'rooty' phenotype was only evident in the etiolated seedling system. Adventitious rooting of etiolated WT seedlings in the presence of exogenous auxin was inhibited by exogenous flavonoids, which act as auxin transport inhibitors; surprisingly, the flavonoid-deficient mutant chs had a lower rooting response compared to WT. Although Arabidopsis is an excellent model system to study adventitious rooting, physiological and developmental responses differed significantly, underlining the importance of avoiding data generalisation on rooting responses derived from different experimental systems with this species.

  2. Phytoplasma effector SAP54 induces indeterminate leaf-like flower development in Arabidopsis plants.

    PubMed

    MacLean, Allyson M; Sugio, Akiko; Makarova, Olga V; Findlay, Kim C; Grieve, Victoria M; Tóth, Réka; Nicolaisen, Mogens; Hogenhout, Saskia A

    2011-10-01

    Phytoplasmas are insect-transmitted bacterial plant pathogens that cause considerable damage to a diverse range of agricultural crops globally. Symptoms induced in infected plants suggest that these phytopathogens may modulate developmental processes within the plant host. We report herein that Aster Yellows phytoplasma strain Witches' Broom (AY-WB) readily infects the model plant Arabidopsis (Arabidopsis thaliana) ecotype Columbia, inducing symptoms that are characteristic of phytoplasma infection, such as the production of green leaf-like flowers (virescence and phyllody) and increased formation of stems and branches (witches' broom). We found that the majority of genes encoding secreted AY-WB proteins (SAPs), which are candidate effector proteins, are expressed in Arabidopsis and the AY-WB insect vector Macrosteles quadrilineatus (Hemiptera; Cicadellidae). To identify which of these effector proteins induce symptoms of phyllody and virescence, we individually expressed the effector genes in Arabidopsis. From this screen, we have identified a novel AY-WB effector protein, SAP54, that alters floral development, resulting in the production of leaf-like flowers that are similar to those produced by plants infected with this phytoplasma. This study offers novel insight into the effector profile of an insect-transmitted plant pathogen and reports to our knowledge the first example of a microbial pathogen effector protein that targets flower development in a host.

  3. 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

  4. ML3: a novel regulator of herbivory-induced responses in Arabidopsis thaliana

    PubMed Central

    Bejai, Sarosh

    2013-01-01

    ML (MD2-related lipid recognition) proteins are known to enhance innate immune responses in mammals. This study reports the analysis of the putative ML gene family in Arabidopsis thaliana and suggests a role for the ML3 gene in herbivory-associated responses in plants. Feeding by larvae of the Lepidopteran generalist herbivore Spodoptera littoralis and larvae of the specialist herbivore Plutella xylostella activated ML3 transcription in leaf tissues. ML3 loss-of-function Arabidopsis plants were compromised in the upregulation of herbivory-induced genes and displayed a semi-dwarf phenotype. Herbivory bioassays showed that larvae of S. littoralis fed on ml3 mutant plants gained more weight compared to larvae fed on wild-type plants while larvae of P. xylostella did not show any significant difference. Virus-induced gene silencing of ML3 expression in plants compromised in jasmonic acid (JA) and salicylic acid (SA) signalling revealed a complex role of ML3 in JA/defence signalling affecting both JA- and SA-dependent responses. The data suggest that ML3 is involved in herbivory-mediated responses in Arabidopsis and that it has a potential role in herbivory-associated molecular pattern recognition. PMID:23314818

  5. Composition and formation of heterochromatin in Arabidopsis thaliana.

    PubMed

    Fransz, P; ten Hoopen, R; Tessadori, F

    2006-01-01

    The term heterochromatin has been applied to both large-scale, microscopically visible chromocentres and small-scale, silent genes located outside chromocentres. This may cause confusion in the interpretation of epigenetic marks for both features. The model plant Arabidopsis thaliana provides an excellent system to investigate composition and function of chromatin states at different levels of organization. In this review we will discuss recent developments in molecular networks underlying gene silencing and the relationship with visible heterochromatin in Arabidopsis.

  6. Probing the stochastic property of endoreduplication in cell size determination of Arabidopsis thaliana leaf epidermal tissue

    PubMed Central

    2017-01-01

    Cell size distribution is highly reproducible, whereas the size of individual cells often varies greatly within a tissue. This is obvious in a population of Arabidopsis thaliana leaf epidermal cells, which ranged from 1,000 to 10,000 μm2 in size. Endoreduplication is a specialized cell cycle in which nuclear genome size (ploidy) is doubled in the absence of cell division. Although epidermal cells require endoreduplication to enhance cellular expansion, the issue of whether this mechanism is sufficient for explaining cell size distribution remains unclear due to a lack of quantitative understanding linking the occurrence of endoreduplication with cell size diversity. Here, we addressed this question by quantitatively summarizing ploidy profile and cell size distribution using a simple theoretical framework. We first found that endoreduplication dynamics is a Poisson process through cellular maturation. This finding allowed us to construct a mathematical model to predict the time evolution of a ploidy profile with a single rate constant for endoreduplication occurrence in a given time. We reproduced experimentally measured ploidy profile in both wild-type leaf tissue and endoreduplication-related mutants with this analytical solution, further demonstrating the probabilistic property of endoreduplication. We next extended the mathematical model by incorporating the element that cell size is determined according to ploidy level to examine cell size distribution. This analysis revealed that cell size is exponentially enlarged 1.5 times every endoreduplication round. Because this theoretical simulation successfully recapitulated experimentally observed cell size distributions, we concluded that Poissonian endoreduplication dynamics and exponential size-boosting are the sources of the broad cell size distribution in epidermal tissue. More generally, this study contributes to a quantitative understanding whereby stochastic dynamics generate steady-state biological

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

    PubMed Central

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

    2014-01-01

    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 13C-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 13CO2 and estimated fluxes throughout leaf photosynthetic metabolism by INST-MFA. Plants grown at 200 µmol m-2s−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 13C 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

  8. Phytochrome A-specific signaling in Arabidopsis thaliana

    PubMed Central

    Kircher, Stefan; Terecskei, Kata; Wolf, Iris; Sipos, Mark

    2011-01-01

    Among the five phytochromes in Arabidopsis thaliana, phytochrome A (phyA) plays a major role in seedling de-etiolation. Until now more then ten positive and some negative components acting downstream of phyA have been identified. However, their site of action and hierarchical relationships are not completely understood yet. PMID:22067110

  9. Involvement of the VEP1 gene in vascular strand development in Arabidopsis thaliana.

    PubMed

    Jun, Ji Hyung; Ha, Chan Man; Nam, Hong Gil

    2002-03-01

    A dominant mutant line characterized by abnormal leaf venation pattern was isolated from a transgenic Arabidopsis plant pool that was generated with Agrobacterium culture harboring an Arabidopsis antisense cDNA library. In the mutant line, the phenotype was due to antisense suppression of a gene we named VEP1 (Vein Patterning). The predicted amino acid sequence of the gene contained a motif related to the mammalian death domain that is found in the apoptotic machinery. Reduced expression of the VEP1 gene resulted in the reduced complexity of the venation pattern of the cotyledons and foliar leaves, which was mainly due to the reduced number of the minor veins and their incomplete connection. The analysis of mutant embryos indicated that the phenotype was originated, at least in part, from a defect in the procambium patterning. In the mutant, the stem and root were thinner than those in wild type. This phenotype was associated with reduced vascular development. The promoter activity of the VEP1 gene was detected preferentially in the vascular regions. We propose that the death domain-containing protein VEP1 functions as a positive element required for vascular strand development in Arabidopsis thaliana.

  10. Chromosome landmarks as tools to study the genome of Arabidopsis thaliana.

    PubMed

    Siroky, J

    2008-01-01

    The model plant Arabidopsis thaliana has long been used for genetic, cellular and molecular studies. Whereas this plant was used as a model of genetics in the 1940's, the first cytogenetic observation of A. thaliana chromosomes was published in the beginning of the 20th century. Although Arabidopsis was not originally considered to be a good plant model for cytogenetics due to smallness of its genome, the number of published chromosome studies has expanded enormously in recent years. The advent of fluorescence in situ hybridization techniques on meiotic chromosomes together with indirect immuno-fluorescence localization of key chromosomal and nuclear proteins and wide accessibility of Arabidopsis mutants have resulted in a synergistic boost in Arabidopsis cytogenetics. In comparison to other plant species, the small genome with under-represented DNA repeats together with a small number of chromosomes makes this model plant easy to comprehend for a cytologist. 2008 S. Karger AG, Basel

  11. Lil3 dimerization and chlorophyll binding in Arabidopsis thaliana.

    PubMed

    Mork-Jansson, Astrid Elisabeth; Gargano, Daniela; Kmiec, Karol; Furnes, Clemens; Shevela, Dmitriy; Eichacker, Lutz Andreas

    2015-10-07

    The two-helix light harvesting like (Lil) protein Lil3 belongs to the family of chlorophyll binding light harvesting proteins of photosynthetic membranes. A function in tetrapyrrol synthesis and stabilization of geranylgeraniol reductase has been shown. Lil proteins contain the chlorophyll a/b-binding motif; however, binding of chlorophyll has not been demonstrated. We find that Lil3.2 from Arabidopsis thaliana forms heterodimers with Lil3.1 and binds chlorophyll. Lil3.2 heterodimerization (25±7.8 nM) is favored relative to homodimerization (431±59 nM). Interaction of Lil3.2 with chlorophyll a (231±49 nM) suggests that heterodimerization precedes binding of chlorophyll in Arabidopsis thaliana. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  12. 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

  13. Arabidopsis thaliana telomeres exhibit euchromatic features

    PubMed Central

    Vaquero-Sedas, María I.; Gámez-Arjona, Francisco M.; Vega-Palas, Miguel A.

    2011-01-01

    Telomere function is influenced by chromatin structure and organization, which usually involves epigenetic modifications. We describe here the chromatin structure of Arabidopsis thaliana telomeres. Based on the study of six different epigenetic marks we show that Arabidopsis telomeres exhibit euchromatic features. In contrast, subtelomeric regions and telomeric sequences present at interstitial chromosomal loci are heterochromatic. Histone methyltransferases and the chromatin remodeling protein DDM1 control subtelomeric heterochromatin formation. Whereas histone methyltransferases are required for histone H3K92Me and non-CpG DNA methylation, DDM1 directs CpG methylation but not H3K92Me or non-CpG methylation. These results argue that both kinds of proteins participate in different pathways to reinforce subtelomeric heterochromatin formation. PMID:21071395

  14. Biochemical properties and subcellular localization of tyrosine aminotransferases in Arabidopsis thaliana.

    PubMed

    Wang, Minmin; Toda, Kyoko; Maeda, Hiroshi A

    2016-12-01

    Plants produce various L-tyrosine (Tyr)-derived compounds that are of pharmaceutical or nutritional importance to humans. Tyr aminotransferase (TAT) catalyzes the reversible transamination between Tyr and 4-hydroxyphenylpyruvate (HPP), the initial step in the biosynthesis of many Tyr-derived plant natural products. Herein reported is the biochemical characterization and subcellular localization of TAT enzymes from the model plant Arabidopsis thaliana. Phylogenetic analysis showed that Arabidopsis has at least two homologous TAT genes, At5g53970 (AtTAT1) and At5g36160 (AtTAT2). Their recombinant enzymes showed distinct biochemical properties: AtTAT1 had the highest activity towards Tyr, while AtTAT2 exhibited a broad substrate specificity for both amino and keto acid substrates. Also, AtTAT1 favored the direction of Tyr deamination to HPP, whereas AtTAT2 preferred transamination of HPP to Tyr. Subcellular localization analysis using GFP-fusion proteins and confocal microscopy showed that AtTAT1, AtTAT2, and HPP dioxygenase (HPPD), which catalyzes the subsequent step of TAT, are localized in the cytosol, unlike plastid-localized Tyr and tocopherol biosynthetic enzymes. Furthermore, subcellular fractionation indicated that, while HPPD activity is restricted to the cytosol, TAT activity is detected in both cytosolic and plastidic fractions of Arabidopsis leaf tissue, suggesting that an unknown aminotransferase(s) having TAT activity is also present in the plastids. Biochemical and cellular analyses of Arabidopsis TATs provide a fundamental basis for future in vivo studies and metabolic engineering for enhanced production of Tyr-derived phytochemicals in plants. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. 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

  16. Transposon diversity in Arabidopsis thaliana

    PubMed Central

    Le, Quang Hien; Wright, Stephen; Yu, Zhihui; Bureau, Thomas

    2000-01-01

    Recent availability of extensive genome sequence information offers new opportunities to analyze genome organization, including transposon diversity and accumulation, at a level of resolution that was previously unattainable. In this report, we used sequence similarity search and analysis protocols to perform a fine-scale analysis of a large sample (≈17.2 Mb) of the Arabidopsis thaliana (Columbia) genome for transposons. Consistent with previous studies, we report that the A. thaliana genome harbors diverse representatives of most known superfamilies of transposons. However, our survey reveals a higher density of transposons of which over one-fourth could be classified into a single novel transposon family designated as Basho, which appears unrelated to any previously known superfamily. We have also identified putative transposase-coding ORFs for miniature inverted-repeat transposable elements (MITEs), providing clues into the mechanism of mobility and origins of the most abundant transposons associated with plant genes. In addition, we provide evidence that most mined transposons have a clear distribution preference for A + T-rich sequences and show that structural variation for many mined transposons is partly due to interelement recombination. Taken together, these findings further underscore the complexity of transposons within the compact genome of A. thaliana. PMID:10861007

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

    DOE PAGES

    Ma, Fangfang; Jazmin, Lara J.; Young, Jamey D.; ...

    2014-11-03

    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 13C-labeling patterns of intracellular metabolites. However, experimental and computational difficulties have hindered its application to terrestrial plant systems. Here, we performed in vivo isotopic labeling of Arabidopsis thaliana rosettes with 13CO 2 and estimated fluxes throughoutmore » leaf photosynthetic metabolism by INST-MFA. Plants grown at 200 µmol m $-$2s $-$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 CO 2 assimilation with high-light acclimation (Vc/Vo: 3.5:1 vs. 2.3:1, respectively). In conclusion, this study highlights the potential of 13C INST-MFA to describe emergent flux phenotypes that respond to environmental conditions or plant physiology and cannot be obtained by other complementary approaches.« less

  18. Biosynthesis and Metabolic Engineering of Anthocyanins in Arabidopsis thaliana

    PubMed Central

    Shi, Ming-Zhu; Xie, De-Yu

    2014-01-01

    Arabidopsis thaliana is the first model plant, the genome of which has been sequenced. In general, intensive studies on this model plant over the past nearly 30 years have led to many new revolutionary understandings in every single aspect of plant biology. Here, we review the current understanding of anthocyanin biosynthesis in this model plant. Although the investigation of anthocyanin structures in this model plant was not performed until 2002, numerous studies over the past three decades have been conducted to understand the biosynthesis of anthocyanins. To date, it appears that all pathway genes of anthocyanins have been molecularly, genetically and biochemically characterized in this plant. These fundamental accomplishments have made Arabidopsis an ideal model to understand the regulatory mechanisms of anthocyanin pathway. Several studies have revealed that the biosynthesis of anthocyanins is controlled by WD40-bHLH-MYB (WBM) transcription factor complexes under lighting conditions. However, how different regulatory complexes coordinately and specifically regulate the pathway genes of anthocyanins remains unclear. In this review, we discuss current progresses and findings including structural diversity, regulatory properties and metabolic engineering of anthocyanins in Arabidopsis thaliana. PMID:24354533

  19. An Arabidopsis thaliana embryo arrest mutant exhibiting germination potential

    USDA-ARS?s Scientific Manuscript database

    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...

  20. Quantitative divergence of the bacterial root microbiota in Arabidopsis thaliana relatives

    PubMed Central

    Schlaeppi, Klaus; Dombrowski, Nina; Oter, Ruben Garrido; Ver Loren van Themaat, Emiel; Schulze-Lefert, Paul

    2014-01-01

    Plants host at the contact zone with soil a distinctive root-associated bacterial microbiota believed to function in plant nutrition and health. We investigated the diversity of the root microbiota within a phylogenetic framework of hosts: three Arabidopsis thaliana ecotypes along with its sister species Arabidopsis halleri and Arabidopsis lyrata, as well as Cardamine hirsuta, which diverged from the former ∼35 Mya. We surveyed their microbiota under controlled environmental conditions and of A. thaliana and C. hirsuta in two natural habitats. Deep 16S rRNA gene profiling of root and corresponding soil samples identified a total of 237 quantifiable bacterial ribotypes, of which an average of 73 community members were enriched in roots. The composition of this root microbiota depends more on interactions with the environment than with host species. Interhost species microbiota diversity is largely quantitative and is greater between the three Arabidopsis species than the three A. thaliana ecotypes. Host species-specific microbiota were identified at the levels of individual community members, taxonomic groups, and whole root communities. Most of these signatures were observed in the phylogenetically distant C. hirsuta. However, the branching order of host phylogeny is incongruent with interspecies root microbiota diversity, indicating that host phylogenetic distance alone cannot explain root microbiota diversification. Our work reveals within 35 My of host divergence a largely conserved and taxonomically narrow root microbiota, which comprises stable community members belonging to the Actinomycetales, Burkholderiales, and Flavobacteriales. PMID:24379374

  1. 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

  2. Proteomic Responses in Arabidopsis thaliana Seedlings Treated with Ethylene

    USDA-ARS?s Scientific Manuscript database

    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,...

  3. Blue light alters miR167 expression and microRNA-targeted auxin response factor genes in Arabidopsis thaliana plants.

    PubMed

    Pashkovskiy, Pavel P; Kartashov, Alexander V; Zlobin, Ilya E; Pogosyan, Sergei I; Kuznetsov, Vladimir V

    2016-07-01

    The effect of blue LED (450 nm) on the photomorphogenesis of Arabidopsis thaliana Col-0 plants and the transcript levels of several genes, including miRNAs, photoreceptors and auxin response factors (ARF) was investigated. It was observed that blue light accelerated the generative development, reduced the rosette leaf number, significantly reduced the leaf area, dry biomass and led to the disruption of conductive tissue formation. The blue LED differentially influenced the transcript levels of several phytochromes (PHY a, b, c, d, and e), cryptochromes (CRY 1 and 2) and phototropins (PHOT 1 and 2). At the same time, the blue LED significantly increased miR167 expression compared to a fluorescent lamp or white LEDs. This increase likely resulted in the enhanced transcription of the auxin response factor genes ARF4 and ARF8, which are regulated by this miRNA. These findings support the hypothesis that the effects of blue light on A. thaliana are mediated by auxin signalling pathway involving miRNA-dependent regulation of ARF gene expression. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  4. Ascorbate-mediated regulation of growth, photoprotection and photoinhibition in Arabidopsis thaliana.

    PubMed

    Plumb, William; Townsend, Alexandra J; Rasool, Brwa; Alomrani, Sarah; Razak, Nurhayati; Karpinska, Barbara; Ruban, Alexander V; Foyer, Christine H

    2018-05-03

    The requirements of growth and photosynthesis for ascorbate were assessed under low (LL; 250 μmol m-2 s-1) or high (HL; 1600 μmol m-2 s-1) irradiance in wild type Arabidopsis thaliana and two ascorbate synthesis mutants (vtc2-1 and vtc2-4) that have 30% wild type ascorbate levels. The low ascorbate mutants had the same numbers of leaves but lower rosette area and biomass than the wild type under LL. Wild type plants experiencing HL had higher leaf ascorbate, anthocyanin and xanthophyll pigments than under LL. In contrast, leaf ascorbate levels were not increased under HL in the mutant lines. While the degree of oxidation measured using an in vivo redox reporter in the nuclei and cytosol of the leaf epidermal and stomatal cells was similar under both irradiances in all lines, anthocyanin levels were significantly lower than in the low ascorbate mutants than the wild type under HL. Differences in the photosynthetic responses of vtc2-1 and vtc2-4 mutants were observed. Unlike vtc2-1, the vtc2-4 mutants had wild type zeaxanthin contents. While both low ascorbate mutants had lower NPQ levels than the wild type under HL, qPd values were greater only in vtc2-1 leaves. Ascorbate is therefore essential for growth but not photoprotection.

  5. Genome-scale cold stress response regulatory networks in ten Arabidopsis thaliana ecotypes

    PubMed Central

    2013-01-01

    Background Low temperature leads to major crop losses every year. Although several studies have been conducted focusing on diversity of cold tolerance level in multiple phenotypically divergent Arabidopsis thaliana (A. thaliana) ecotypes, genome-scale molecular understanding is still lacking. Results In this study, we report genome-scale transcript response diversity of 10 A. thaliana ecotypes originating from different geographical locations to non-freezing cold stress (10°C). To analyze the transcriptional response diversity, we initially compared transcriptome changes in all 10 ecotypes using Arabidopsis NimbleGen ATH6 microarrays. In total 6061 transcripts were significantly cold regulated (p < 0.01) in 10 ecotypes, including 498 transcription factors and 315 transposable elements. The majority of the transcripts (75%) showed ecotype specific expression pattern. By using sequence data available from Arabidopsis thaliana 1001 genome project, we further investigated sequence polymorphisms in the core cold stress regulon genes. Significant numbers of non-synonymous amino acid changes were observed in the coding region of the CBF regulon genes. Considering the limited knowledge about regulatory interactions between transcription factors and their target genes in the model plant A. thaliana, we have adopted a powerful systems genetics approach- Network Component Analysis (NCA) to construct an in-silico transcriptional regulatory network model during response to cold stress. The resulting regulatory network contained 1,275 nodes and 7,720 connections, with 178 transcription factors and 1,331 target genes. Conclusions A. thaliana ecotypes exhibit considerable variation in transcriptome level responses to non-freezing cold stress treatment. Ecotype specific transcripts and related gene ontology (GO) categories were identified to delineate natural variation of cold stress regulated differential gene expression in the model plant A. thaliana. The predicted

  6. The short-term response of Arabidopsis thaliana (C3) and Zea mays (C4) chloroplasts to red and far red light.

    PubMed

    Zienkiewicz, Maksymilian; Drożak, Anna; Wasilewska, Wioleta; Bacławska, Ilona; Przedpełska-Wąsowicz, Ewa; Romanowska, Elżbieta

    2015-12-01

    Light quality has various effects on photochemistry and protein phosphorylation in Zea mays and Arabidopsis thaliana thylakoids due to different degrees of light penetration across leaves and redox status in chloroplasts. The effect of the spectral quality of light (red, R and far red, FR) on the function of thylakoid proteins in Zea mays and Arabidopsis thaliana was investigated. It was concluded that red light stimulates PSII activity in A. thaliana thylakoids and in maize bundle sheath (BS) thylakoids, but not in mesophyll (M) thylakoids. The light quality did not change PSI activity in M thylakoids of maize. FR used after a white light period increased PSI activity significantly in maize BS and only slightly in A. thaliana thylakoids. As shown by blue native (BN)-PAGE followed by SDS-PAGE, proteins were differently phosphorylated in the thylakoids, indicating their different functions. FR light increased dephosphorylation of LHCII proteins in A. thaliana thylakoids, whereas in maize, dephosphorylation did not occur at all. The rate of phosphorylation was higher in maize BS than in M thylakoids. D1 protein phosphorylation increased in maize and decreased in A. thaliana upon irradiation with both R and growth light (white light, W). Light variations did not change the level of proteins in thylakoids. Our data strongly suggest that response to light quality is a species-dependent phenomenon. We concluded that the maize chloroplasts were differently stimulated, probably due to different degrees of light penetration across the leaf and thereby the redox status in the chloroplasts. These acclimation changes induced by light quality are important in the regulation of chloroplast membrane flexibility and thus its function.

  7. Modulation of ethylene- and heat-controlled hyponastic leaf movement in Arabidopsis thaliana by the plant defence hormones jasmonate and salicylate.

    PubMed

    van Zanten, Martijn; Ritsema, Tita; Polko, Joanna K; Leon-Reyes, Antonio; Voesenek, Laurentius A C J; Millenaar, Frank F; Pieterse, Corné M J; Peeters, Anton J M

    2012-04-01

    Upward leaf movement (hyponastic growth) is adopted by several plant species including Arabidopsis thaliana, as a mechanism to escape adverse growth conditions. Among the signals that trigger hyponastic growth are, the gaseous hormone ethylene, low light intensities, and supra-optimal temperatures (heat). Recent studies indicated that the defence-related phytohormones jasmonic acid (JA) and salicylic acid (SA) synthesized by the plant upon biotic infestation repress low light-induced hyponastic growth. The hyponastic growth response induced by high temperature (heat) treatment and upon application of the gaseous hormone ethylene is highly similar to the response induced by low light. To test if these environmental signals induce hyponastic growth via parallel pathways or converge downstream, we studied here the roles of Methyl-JA (MeJA) and SA on ethylene- and heat-induced hyponastic growth. For this, we used a time-lapse camera setup. Our study includes pharmacological application of MeJA and SA and biological infestation using the JA-inducing caterpillar Pieris rapae as well as mutants lacking JA or SA signalling components. The data demonstrate that MeJA is a positive, and SA, a negative regulator of ethylene-induced hyponastic growth and that both hormones repress the response to heat. Taking previous studies into account, we conclude that SA is the first among many tested components which is repressing hyponastic growth under all tested inductive environmental stimuli. However, since MeJA is a positive regulator of ethylene-induced hyponastic growth and is inhibiting low light- and heat-induced leaf movement, we conclude that defence hormones control hyponastic growth by affecting stimulus-specific signalling pathways.

  8. Proteomic Identification of Putative MicroRNA394 Target Genes in Arabidopsis thaliana Identifies Major Latex Protein Family Members Critical for Normal Development.

    PubMed

    Litholdo, Celso G; Parker, Benjamin L; Eamens, Andrew L; Larsen, Martin R; Cordwell, Stuart J; Waterhouse, Peter M

    2016-06-01

    Expression of the F-Box protein Leaf Curling Responsiveness (LCR) is regulated by microRNA, miR394, and alterations to this interplay in Arabidopsis thaliana produce defects in leaf polarity and shoot apical meristem organization. Although the miR394-LCR node has been documented in Arabidopsis, the identification of proteins targeted by LCR F-box itself has proven problematic. Here, a proteomic analysis of shoot apices from plants with altered LCR levels identified a member of the Latex Protein (MLP) family gene as a potential LCR F-box target. Bioinformatic and molecular analyses also suggested that other MLP family members are likely to be targets for this post-translational regulation. Direct interaction between LCR F-Box and MLP423 was validated. Additional MLP members had reduction in protein accumulation, in varying degrees, mediated by LCR F-Box. Transgenic Arabidopsis lines, in which MLP28 expression was reduced through an artificial miRNA technology, displayed severe developmental defects, including changes in leaf patterning and morphology, shoot apex defects, and eventual premature death. These phenotypic characteristics resemble those of Arabidopsis plants modified to over-express LCR Taken together, the results demonstrate that MLPs are driven to degradation by LCR, and indicate that MLP gene family is target of miR394-LCR regulatory node, representing potential targets for directly post-translational regulation mediated by LCR F-Box. In addition, MLP28 family member is associated with the LCR regulation that is critical for normal Arabidopsis development. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  9. Proteomic Identification of Putative MicroRNA394 Target Genes in Arabidopsis thaliana Identifies Major Latex Protein Family Members Critical for Normal Development*

    PubMed Central

    Litholdo, Celso G.; Parker, Benjamin L.; Eamens, Andrew L.; Larsen, Martin R.; Cordwell, Stuart J.; Waterhouse, Peter M.

    2016-01-01

    Expression of the F-Box protein Leaf Curling Responsiveness (LCR) is regulated by microRNA, miR394, and alterations to this interplay in Arabidopsis thaliana produce defects in leaf polarity and shoot apical meristem organization. Although the miR394-LCR node has been documented in Arabidopsis, the identification of proteins targeted by LCR F-box itself has proven problematic. Here, a proteomic analysis of shoot apices from plants with altered LCR levels identified a member of the Latex Protein (MLP) family gene as a potential LCR F-box target. Bioinformatic and molecular analyses also suggested that other MLP family members are likely to be targets for this post-translational regulation. Direct interaction between LCR F-Box and MLP423 was validated. Additional MLP members had reduction in protein accumulation, in varying degrees, mediated by LCR F-Box. Transgenic Arabidopsis lines, in which MLP28 expression was reduced through an artificial miRNA technology, displayed severe developmental defects, including changes in leaf patterning and morphology, shoot apex defects, and eventual premature death. These phenotypic characteristics resemble those of Arabidopsis plants modified to over-express LCR. Taken together, the results demonstrate that MLPs are driven to degradation by LCR, and indicate that MLP gene family is target of miR394-LCR regulatory node, representing potential targets for directly post-translational regulation mediated by LCR F-Box. In addition, MLP28 family member is associated with the LCR regulation that is critical for normal Arabidopsis development. PMID:27067051

  10. 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

  11. 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. © 2014 Scandinavian Plant Physiology Society.

  12. Arabidopsis Leaf Trichomes as Acoustic Antennae.

    PubMed

    Liu, Shaobao; Jiao, Jiaojiao; Lu, Tian Jian; Xu, Feng; Pickard, Barbara G; Genin, Guy M

    2017-11-07

    The much studied plant Arabidopsis thaliana has been reported recently to react to the sounds of caterpillars of Pieris rapae chewing on its leaves by promoting synthesis of toxins that can deter herbivory. Identifying participating receptor cells-potential "ears"-of Arabidopsis is critical to understanding and harnessing this response. Motivated in part by other recent observations that Arabidopsis trichomes (hair cells) respond to mechanical stimuli such as pressing or brushing by initiating potential signaling factors in themselves and in the neighboring skirt of cells, we analyzed the vibrational responses of Arabidopsis trichomes to test the hypothesis that trichomes can respond acoustically to vibrations associated with feeding caterpillars. We found that these trichomes have vibrational modes in the frequency range of the sounds of feeding caterpillars, encouraging further experimentation to determine whether trichomes serve as mechanical antennae. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  13. Phytoplasma Effector SAP54 Induces Indeterminate Leaf-Like Flower Development in Arabidopsis Plants1[C][W][OA

    PubMed Central

    MacLean, Allyson M.; Sugio, Akiko; Makarova, Olga V.; Findlay, Kim C.; Grieve, Victoria M.; Tóth, Réka; Nicolaisen, Mogens; Hogenhout, Saskia A.

    2011-01-01

    Phytoplasmas are insect-transmitted bacterial plant pathogens that cause considerable damage to a diverse range of agricultural crops globally. Symptoms induced in infected plants suggest that these phytopathogens may modulate developmental processes within the plant host. We report herein that Aster Yellows phytoplasma strain Witches’ Broom (AY-WB) readily infects the model plant Arabidopsis (Arabidopsis thaliana) ecotype Columbia, inducing symptoms that are characteristic of phytoplasma infection, such as the production of green leaf-like flowers (virescence and phyllody) and increased formation of stems and branches (witches’ broom). We found that the majority of genes encoding secreted AY-WB proteins (SAPs), which are candidate effector proteins, are expressed in Arabidopsis and the AY-WB insect vector Macrosteles quadrilineatus (Hemiptera; Cicadellidae). To identify which of these effector proteins induce symptoms of phyllody and virescence, we individually expressed the effector genes in Arabidopsis. From this screen, we have identified a novel AY-WB effector protein, SAP54, that alters floral development, resulting in the production of leaf-like flowers that are similar to those produced by plants infected with this phytoplasma. This study offers novel insight into the effector profile of an insect-transmitted plant pathogen and reports to our knowledge the first example of a microbial pathogen effector protein that targets flower development in a host. PMID:21849514

  14. Seed-to-seed growth of Arabidopsis thaliana on the International Space Station

    NASA Technical Reports Server (NTRS)

    Link, B. M.; Durst, S. J.; Zhou, W.; Stankovic, B.

    2003-01-01

    The assembly of the International Space Station (ISS) as a permanent experimental outpost has provided the opportunity for quality plant research in space. To take advantage of this orbital laboratory, engineers and scientists at the Wisconsin Center for Space Automation and Robotics (WCSAR), University of Wisconsin-Madison, developed a plant growth facility capable of supporting plant growth in the microgravity environment. Utilizing this Advanced Astroculture (ADVASC) plant growth facility, an experiment was conducted with the objective to grow Arabidopsis thaliana plants from seed-to-seed on the ISS. Dry Arabidopsis seeds were anchored in the root tray of the ADVASC growth chamber. These seeds were successfully germinated from May 10 until the end of June 2001. Arabidopsis plants grew and completed a full life cycle in microgravity. This experiment demonstrated that ADVASC is capable of providing environment conditions suitable for plant growth and development in microgravity. The normal progression through the life cycle, as well as the postflight morphometric analyses, demonstrate that Arabidopsis thaliana does not require the presence of gravity for growth and development. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

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

    PubMed

    Krämer, Ute

    2015-03-25

    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.

  16. Regulation of miR163 and its targets in defense against Pseudomonas syringae in Arabidopsis thaliana.

    PubMed

    Chow, Hiu Tung; Ng, Danny W-K

    2017-04-12

    Small RNAs are important regulators for a variety of biological processes, including leaf development, flowering-time, embryogenesis and defense responses. miR163 is a non-conserved miRNA and its locus has evolved recently through inverted duplication of its target genes to which they belong to the SABATH family of related small-molecule methyltransferases (MTs). In Arabidopsis thaliana, previous study demonstrated that miR163 accumulation was induced by alamethicin treatment, suggesting its roles in defense response pathways. Enhanced resistance against Pseudomonas syringae pv. tomato (Pst) was observed in the mir163 mutant, whereas transgenic lines overexpressing miR163 showed increase sensitivity to Pst, suggesting that miR163 is a negative regulator of defense response. Elevated level of miR163 and its targets in A. thaliana were observed upon Pst treatment, suggesting a modulating relationship between miR163 and its targets. In addition, miR163 and histone deacetylase were found to act cooperatively in mediating defense against Pst. Transgenic plants overexpressing miR163-resistant targets suggested their different contributions in defense. Results from this study revealed that the stress-inducible miR163 and its targets act in concert to modulate defense responses against bacterial pathogen in A. thaliana.

  17. 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.

  18. 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. © 2014 American Society of Plant Biologists. All rights reserved.

  19. Acclimation of Swedish and Italian ecotypes of Arabidopsis thaliana to light intensity.

    PubMed

    Stewart, Jared J; Polutchko, Stephanie K; Adams, William W; Demmig-Adams, Barbara

    2017-11-01

    This study addressed whether ecotypes of Arabidopsis thaliana from Sweden and Italy exhibited differences in foliar acclimation to high versus low growth light intensity, and compared CO 2 uptake under growth conditions with light- and CO 2 -saturated intrinsic photosynthetic capacity and leaf morphological and vascular features. Differential responses between ecotypes occurred mainly at the scale of leaf architecture, with thicker leaves with higher intrinsic photosynthetic capacities and chlorophyll contents per leaf area, but no difference in photosynthetic capacity on a chlorophyll basis, in high light-grown leaves of the Swedish versus the Italian ecotype. Greater intrinsic photosynthetic capacity per leaf area in the Swedish ecotype was accompanied by a greater capacity of vascular infrastructure for sugar and water transport, but this was not associated with greater CO 2 uptake rates under growth conditions. The Swedish ecotype with its thick leaves is thus constructed for high intrinsic photosynthetic and vascular flux capacity even under growth chamber conditions that may not permit full utilization of this potential. Conversely, the Swedish ecotype was less tolerant of low growth light intensity than the Italian ecotype, with smaller rosette areas and lesser aboveground biomass accumulation in low light-grown plants. Foliar vein density and stomatal density were both enhanced by high growth light intensity with no significant difference between ecotypes, and the ratio of water to sugar conduits was also similar between the two ecotypes during light acclimation. These findings add to the understanding of the foliar vasculature's role in plant photosynthetic acclimation and adaptation.

  20. The heterologous expression of a chrysanthemum TCP-P transcription factor CmTCP14 suppresses organ size and delays senescence in Arabidopsis thaliana.

    PubMed

    Zhang, Ting; Qu, Yixin; Wang, Haibin; Wang, Jingjing; Song, Aiping; Hu, Yueheng; Chen, Sumei; Jiang, Jiafu; Chen, Fadi

    2017-06-01

    TCP transcription factors are important for plant growth and development, but their activity in chrysanthemum (Chrysanthemum morifolium) has not been thoroughly explored. Here, a chrysanthemum TCP-P sequence, which encodes a protein harboring the conserved basic helix-loop-helix (bHLH) motif, was shown to be related phylogenetically to the Arabidopsis thaliana gene AtTCP14. A yeast-one hybrid assay showed that the encoding protein had no transcriptional activation ability, and a localization experiment indicated that it was localized in the nucleus. Transcription profiling established that the gene was most active in the stem and leaf. Its heterologous expression in A. thaliana down-regulated certain cell cycle-related genes, reduced the size of various organs and increased the chlorophyll and carotenoid contents of the leaf which led to delayed senescence and a prolonged flowering period. Moreover, by screening the cDNA library of chrysanthemum, we found that the CmTCP14 can interact with CmFTL2 and some CmDELLAs. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  1. Salt-specific regulation of the cytosolic O-acetylserine(thiol)lyase gene from Arabidopsis thaliana is dependent on abscisic acid.

    PubMed

    Barroso, C; Romero, L C; Cejudo, F J; Vega, J M; Gotor, C

    1999-07-01

    The expression of Atcys-3A gene coding for cytosolic O-acetylserine(thiol)lyase, a key enzyme in cysteine biosynthesis, from Arabidopsis thaliana is significantly induced by exposure to salt and heavy-metal stresses. Addition of NaCl to mature plants induced a rapid accumulation of the mRNA throughout the leaf lamina and roots, and later on in stems, being mainly restricted to vascular tissues. The salt-specific regulation of Atcys-3A was also mediated by abscisic acid (ABA) since: (1) exogenous addition of ABA to the culture medium mimicked the salt-induced plant response by raising the level of Atcys-3A transcript, and (2) Arabidopsis mutants aba-1 and abi2-1 were not able to respond to NaCl. Our results suggest that a high rate of cysteine biosynthesis is required in Arabidopsis under salt stress necessary for a plant protection or adaptation mechanism. This hypothesis was supported by the observation that intracellular levels of cysteine and glutathione increased up to 3-fold after salt treatment.

  2. Novel allelic variants in ACD6 cause hybrid necrosis in local collection of Arabidopsis thaliana.

    PubMed

    Świadek, Magdalena; Proost, Sebastian; Sieh, Daniela; Yu, Jing; Todesco, Marco; Jorzig, Christian; Rodriguez Cubillos, Andrés Eduardo; Plötner, Björn; Nikoloski, Zoran; Chae, Eunyoung; Giavalisco, Patrick; Fischer, Axel; Schröder, Florian; Kim, Sang-Tae; Weigel, Detlef; Laitinen, Roosa A E

    2017-01-01

    Hybrid necrosis is a common type of hybrid incompatibility in plants. This phenomenon is caused by deleterious epistatic interactions, resulting in spontaneous activation of plant defenses associated with leaf necrosis, stunted growth and reduced fertility in hybrids. Specific combinations of alleles of ACCELERATED CELL DEATH 6 (ACD6) have been shown to be a common cause of hybrid necrosis in Arabidopsis thaliana. Increased ACD6 activity confers broad-spectrum resistance against biotrophic pathogens but reduces biomass production. We generated 996 crosses among individuals derived from a single collection area around Tübingen (Germany) and screened them for hybrid necrosis. Necrotic hybrids were further investigated by genetic linkage, amiRNA silencing, genomic complementation and metabolic profiling. Restriction site associated DNA (RAD)-sequencing was used to understand genetic diversity in the collection sites containing necrosis-inducing alleles. Novel combinations of ACD6 alleles found in neighbouring stands were found to activate the A. thaliana immune system. In contrast to what we observed in controlled conditions, necrotic hybrids did not show reduced fitness in the field. Metabolic profiling revealed changes associated with the activation of the immune system in ACD6-dependent hybrid necrosis. This study expands our current understanding of the active role of ACD6 in mediating trade-offs between defense responses and growth in A.  thaliana. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  3. 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.

  4. Genome scale transcriptional response diversity among ten ecotypes of Arabidopsis thaliana during heat stress

    PubMed Central

    Barah, Pankaj; Jayavelu, Naresh D.; Mundy, John; Bones, Atle M.

    2013-01-01

    In the scenario of global warming and climate change, heat stress is a serious threat to crop production worldwide. Being sessile, plants cannot escape from heat. Plants have developed various adaptive mechanisms to survive heat stress. Several studies have focused on diversity of heat tolerance levels in divergent Arabidopsis thaliana (A. thaliana) ecotypes, but comprehensive genome scale understanding of heat stress response in plants is still lacking. Here we report the genome scale transcript responses to heat stress of 10 A. thaliana ecotypes (Col, Ler, C24, Cvi, Kas1, An1, Sha, Kyo2, Eri, and Kond) originated from different geographical locations. During the experiment, A. thaliana plants were subjected to heat stress (38°C) and transcript responses were monitored using Arabidopsis NimbleGen ATH6 microarrays. The responses of A. thaliana ecotypes exhibited considerable variation in the transcript abundance levels. In total, 3644 transcripts were significantly heat regulated (p < 0.01) in the 10 ecotypes, including 244 transcription factors and 203 transposable elements. By employing a systems genetics approach- Network Component Analysis (NCA), we have constructed an in silico transcript regulatory network model for 35 heat responsive transcription factors during cellular responses to heat stress in A. thaliana. The computed activities of the 35 transcription factors showed ecotype specific responses to the heat treatment. PMID:24409190

  5. Arabidopsis REGULATOR OF AXILLARY MERISTEMS1 controls a leaf axil stem cell niche and modulates vegetative development.

    PubMed

    Keller, Thomas; Abbott, Jessica; Moritz, Thomas; Doerner, Peter

    2006-03-01

    Shoot branching is a major determinant of variation in plant stature. Branches, which form secondary growth axes, originate from stem cells activated in leaf axils. The initial steps by which axillary meristems (AMs) are specified and their stem cells organized are still poorly understood. We identified gain- and loss-of-function alleles at the Arabidopsis thaliana REGULATOR OF AXILLARY MERISTEMS1 (RAX1) locus. RAX1 is encoded by the Myb-like transcription factor MYB37 and is an Arabidopsis homolog of the tomato (Solanum lycopersicum) Blind gene. RAX1 is transiently expressed in a small central domain within the boundary zone separating shoot apical meristem and leaf primordia early in leaf primordium development. RAX1 genetically interacts with CUP-SHAPED COTYLEDON (CUC) genes and is required for the expression of CUC2 in the RAX1 expression domain, suggesting that RAX1 acts through CUC2. We propose that RAX1 functions to positionally specify a stem cell niche for AM formation. RAX1 also affects the timing of developmental phase transitions by negatively regulating gibberellic acid levels in the shoot apex. RAX1 thus defines a novel activity that links the specification of AM formation with the modulation of the rate of progression through developmental phases.

  6. MIPS Arabidopsis thaliana Database (MAtDB): an integrated biological knowledge resource for plant genomics

    PubMed Central

    Schoof, Heiko; Ernst, Rebecca; Nazarov, Vladimir; Pfeifer, Lukas; Mewes, Hans-Werner; Mayer, Klaus F. X.

    2004-01-01

    Arabidopsis thaliana is the most widely studied model plant. Functional genomics is intensively underway in many laboratories worldwide. Beyond the basic annotation of the primary sequence data, the annotated genetic elements of Arabidopsis must be linked to diverse biological data and higher order information such as metabolic or regulatory pathways. The MIPS Arabidopsis thaliana database MAtDB aims to provide a comprehensive resource for Arabidopsis as a genome model that serves as a primary reference for research in plants and is suitable for transfer of knowledge to other plants, especially crops. The genome sequence as a common backbone serves as a scaffold for the integration of data, while, in a complementary effort, these data are enhanced through the application of state-of-the-art bioinformatics tools. This information is visualized on a genome-wide and a gene-by-gene basis with access both for web users and applications. This report updates the information given in a previous report and provides an outlook on further developments. The MAtDB web interface can be accessed at http://mips.gsf.de/proj/thal/db. PMID:14681437

  7. Hydrogen isotope composition of leaf wax n-alkanes in Arabidopsis lines with different transpiration rates

    NASA Astrophysics Data System (ADS)

    Pedentchouk, N.; Lawson, T.; Eley, Y.; McAusland, L.

    2012-04-01

    Stable isotopic compositions of oxygen and hydrogen are used widely to investigate modern and ancient water cycles. The D/H composition of organic compounds derived from terrestrial plants has recently attracted significant attention as a proxy for palaeohydrology. However, the role of various plant physiological and biochemical factors in controlling the D/H signature of leaf wax lipids in extant plants remains unclear. The focus of this study is to investigate the effect of plant transpiration on the D/H composition of n-alkanes in terrestrial plants. This experiment includes 4 varieties of Arabidopsis thaliana that differ with respect to stomatal density and stomatal geometry. All 4 varieties were grown indoors under identical temperature, relative humidity, light and watering regimes and then sampled for leaf wax and leaf water stable isotopic measurements. During growth, stomatal conductance to carbon dioxide and water vapour were also determined. We found that the plants varied significantly in terms of their transpiration rates. Transpiration rates were significantly higher in Arabidopsis ost1 and ost1-1 varieties (2.4 and 3.2 mmol m-2 s-1, respectively) than in Arabidopsis RbohD and Col-0 (1.5 and 1.4). However, hydrogen isotope measurements of n-alkanes extracted from leaf waxes revealed a very different pattern. Varieties ost1, ost1-1, and RbohD have very similar deltaD values of n-C29 alkane (-125, -128, and -127 per mil), whereas the deltaD value of Col-0 is more negative (-137 per mil). The initial results of this work suggest that plant transpiration is decoupled from the D/H composition of n-alkanes. In other words, physical processes that affect water vapour movement between the plant and its environment apparently cannot account for the stable hydrogen isotope composition of organic compounds that comprise leaf waxes. Additional, perhaps biochemical, processes that affect hydrogen isotope fractionation during photosynthesis might need to be invoked

  8. PHENOPSIS DB: an Information System for Arabidopsis thaliana phenotypic data in an environmental context

    PubMed Central

    2011-01-01

    Background Renewed interest in plant × environment interactions has risen in the post-genomic era. In this context, high-throughput phenotyping platforms have been developed to create reproducible environmental scenarios in which the phenotypic responses of multiple genotypes can be analysed in a reproducible way. These platforms benefit hugely from the development of suitable databases for storage, sharing and analysis of the large amount of data collected. In the model plant Arabidopsis thaliana, most databases available to the scientific community contain data related to genetic and molecular biology and are characterised by an inadequacy in the description of plant developmental stages and experimental metadata such as environmental conditions. Our goal was to develop a comprehensive information system for sharing of the data collected in PHENOPSIS, an automated platform for Arabidopsis thaliana phenotyping, with the scientific community. Description PHENOPSIS DB is a publicly available (URL: http://bioweb.supagro.inra.fr/phenopsis/) information system developed for storage, browsing and sharing of online data generated by the PHENOPSIS platform and offline data collected by experimenters and experimental metadata. It provides modules coupled to a Web interface for (i) the visualisation of environmental data of an experiment, (ii) the visualisation and statistical analysis of phenotypic data, and (iii) the analysis of Arabidopsis thaliana plant images. Conclusions Firstly, data stored in the PHENOPSIS DB are of interest to the Arabidopsis thaliana community, particularly in allowing phenotypic meta-analyses directly linked to environmental conditions on which publications are still scarce. Secondly, data or image analysis modules can be downloaded from the Web interface for direct usage or as the basis for modifications according to new requirements. Finally, the structure of PHENOPSIS DB provides a useful template for the development of other similar

  9. Functional characterization of Arabidopsis thaliana transthyretin-like protein.

    PubMed

    Pessoa, João; Sárkány, Zsuzsa; Ferreira-da-Silva, Frederico; Martins, Sónia; Almeida, Maria R; Li, Jianming; Damas, Ana M

    2010-02-18

    Arabidopsis thaliana transthyretin-like (TTL) protein is a potential substrate in the brassinosteroid signalling cascade, having a role that moderates plant growth. Moreover, sequence homology revealed two sequence domains similar to 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline (OHCU) decarboxylase (N-terminal domain) and 5-hydroxyisourate (5-HIU) hydrolase (C-terminal domain). TTL is a member of the transthyretin-related protein family (TRP), which comprises a number of proteins with sequence homology to transthyretin (TTR) and the characteristic C-terminal sequence motif Tyr-Arg-Gly-Ser. TRPs are single domain proteins that form tetrameric structures with 5-HIU hydrolase activity. Experimental evidence is fundamental for knowing if TTL is a tetrameric protein, formed by the association of the 5-HIU hydrolase domains and, in this case, if the structural arrangement allows for OHCU decarboxylase activity. This work reports about the biochemical and functional characterization of TTL. The TTL gene was cloned and the protein expressed and purified for biochemical and functional characterization. The results show that TTL is composed of four subunits, with a moderately elongated shape. We also found evidence for 5-HIU hydrolase and OHCU decarboxylase activities in vitro, in the full-length protein. The Arabidopsis thaliana transthyretin-like (TTL) protein is a tetrameric bifunctional enzyme, since it has 5-HIU hydrolase and OHCU decarboxylase activities, which were simultaneously observed in vitro.

  10. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. MIPS Arabidopsis thaliana Database (MAtDB): an integrated biological knowledge resource based on the first complete plant genome

    PubMed Central

    Schoof, Heiko; Zaccaria, Paolo; Gundlach, Heidrun; Lemcke, Kai; Rudd, Stephen; Kolesov, Grigory; Arnold, Roland; Mewes, H. W.; Mayer, Klaus F. X.

    2002-01-01

    Arabidopsis thaliana is the first plant for which the complete genome has been sequenced and published. Annotation of complex eukaryotic genomes requires more than the assignment of genetic elements to the sequence. Besides completing the list of genes, we need to discover their cellular roles, their regulation and their interactions in order to understand the workings of the whole plant. The MIPS Arabidopsis thaliana Database (MAtDB; http://mips.gsf.de/proj/thal/db) started out as a repository for genome sequence data in the European Scientists Sequencing Arabidopsis (ESSA) project and the Arabidopsis Genome Initiative. Our aim is to transform MAtDB into an integrated biological knowledge resource by integrating diverse data, tools, query and visualization capabilities and by creating a comprehensive resource for Arabidopsis as a reference model for other species, including crop plants. PMID:11752263

  12. 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.

  13. Leaf Oil Body Functions as a Subcellular Factory for the Production of a Phytoalexin in Arabidopsis1[W

    PubMed Central

    Shimada, Takashi L.; Takano, Yoshitaka; Shimada, Tomoo; Fujiwara, Masayuki; Fukao, Yoichiro; Mori, Masashi; Okazaki, Yozo; Saito, Kazuki; Sasaki, Ryosuke; Aoki, Koh; Hara-Nishimura, Ikuko

    2014-01-01

    Oil bodies are intracellular structures present in the seed and leaf cells of many land plants. Seed oil bodies are known to function as storage compartments for lipids. However, the physiological function of leaf oil bodies is unknown. Here, we show that leaf oil bodies function as subcellular factories for the production of a stable phytoalexin in response to fungal infection and senescence. Proteomic analysis of oil bodies prepared from Arabidopsis (Arabidopsis thaliana) leaves identified caleosin (CLO3) and α-dioxygenase (α-DOX1). Both CLO3 and α-DOX1 were localized on the surface of oil bodies. Infection with the pathogenic fungus Colletotrichum higginsianum promoted the formation of CLO3- and α-DOX1-positive oil bodies in perilesional areas surrounding the site of infection. α-DOX1 catalyzes the reaction from α-linolenic acid (a major fatty acid component of oil bodies) to an unstable compound, 2-hydroperoxy-octadecatrienoic acid (2-HPOT). Intriguingly, a combination of α-DOX1 and CLO3 produced a stable compound, 2-hydroxy-octadecatrienoic acid (2-HOT), from α-linolenic acid. This suggests that the colocalization of α-DOX1 and CLO3 on oil bodies might prevent the degradation of unstable 2-HPOT by efficiently converting 2-HPOT into the stable compound 2-HOT. We found that 2-HOT had antifungal activity against members of the genus Colletotrichum and that infection with C. higginsianum induced 2-HOT production. These results defined 2-HOT as an Arabidopsis phytoalexin. This study provides, to our knowledge, the first evidence that leaf oil bodies produce a phytoalexin under a pathological condition, which suggests a new mechanism of plant defense. PMID:24214535

  14. OLIGOCELLULA1/HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENES15 Promotes Cell Proliferation With HISTONE DEACETYLASE9 and POWERDRESS During Leaf Development in Arabidopsis thaliana

    PubMed Central

    Suzuki, Marina; Shinozuka, Nanae; Hirakata, Tomohiro; Nakata, Miyuki T.; Demura, Taku; Tsukaya, Hirokazu; Horiguchi, Gorou

    2018-01-01

    Organ size regulation is dependent on the precise spatial and temporal regulation of cell proliferation and cell expansion. A number of transcription factors have been identified that play a key role in the determination of aerial lateral organ size, but their functional relationship to various chromatin modifiers has not been well understood. To understand how leaf size is regulated, we previously isolated the oligocellula1 (oli1) mutant of Arabidopsis thaliana that develops smaller first leaves than the wild type (WT) mainly due to a reduction in the cell number. In this study, we further characterized oli1 leaf phenotypes and identified the OLI1 gene as well as interaction partners of OLI1. Detailed characterizations of leaf development suggested that the cell proliferation rate in oli1 leaf primordia is lower than that in the WT. In addition, oli1 was associated with a slight delay of the progression from the juvenile to adult phases of leaf traits. A classical map-based approach demonstrated that OLI1 is identical to HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENES15 (HOS15). HOS15/OLI1 encodes a homolog of human transducin β-like protein1 (TBL1). TBL1 forms a transcriptional repression complex with the histone deacetylase (HDAC) HDAC3 and either nuclear receptor co-repressor (N-CoR) or silencing mediator for retinoic acid and thyroid receptor (SMRT). We found that mutations in HISTONE DEACETYLASE9 (HDA9) and a switching-defective protein 3, adaptor 2, N-CoR, and transcription factor IIIB-domain protein gene, POWERDRESS (PWR), showed a small-leaf phenotype similar to oli1. In addition, hda9 and pwr did not further enhance the oli1 small-leaf phenotype, suggesting that these three genes act in the same pathway. Yeast two-hybrid assays suggested physical interactions, wherein PWR probably bridges HOS15/OLI1 and HDA9. Earlier studies suggested the roles of HOS15, HDA9, and PWR in transcriptional repression. Consistently, transcriptome analyses showed several

  15. Aberrant temporal growth pattern and morphology of root and shoot caused by a defective circadian clock in Arabidopsis thaliana.

    PubMed

    Ruts, Tom; Matsubara, Shizue; Wiese-Klinkenberg, Anika; Walter, Achim

    2012-10-01

    Circadian clocks synchronized with the environment allow plants to anticipate recurring daily changes and give a fitness advantage. Here, we mapped the dynamic growth phenotype of leaves and roots in two lines of Arabidopsis thaliana with a disrupted circadian clock: the CCA1 over-expressing line (CCA1ox) and the prr9 prr7 prr5 (prr975) mutant. We demonstrate leaf growth defects due to a disrupted circadian clock over a 24 h time scale. Both lines showed enhanced leaf growth compared with the wild-type during the diurnal period, suggesting increased partitioning of photosynthates for leaf growth. Nocturnal leaf growth was reduced and growth inhibition occurred by dawn, which may be explained by ineffective starch degradation in the leaves of the mutants. However, this growth inhibition was not caused by starch exhaustion. Overall, these results are consistent with the notion that the defective clock affects carbon and energy allocation, thereby reducing growth capacity during the night. Furthermore, rosette morphology and size as well as root architecture were strikingly altered by the defective clock control. Separate analysis of the primary root and lateral roots revealed strong suppression of lateral root formation in both CCA1ox and prr975, accompanied by unusual changes in lateral root growth direction under light-dark cycles and increased lateral extension of the root system. We conclude that growth of the whole plant is severely affected by improper clock regulation in A. thaliana, resulting not only in altered timing and capacity for growth but also aberrant development of shoot and root architecture. © 2012 Forschungszentrum Jülich. The Plant Journal © 2012 Blackwell Publishing Ltd.

  16. Nitrite reductase expression is regulated at the post-transcriptional level by the nitrogen source in Nicotiana plumbaginifolia and Arabidopsis thaliana.

    PubMed

    Crété, P; Caboche, M; Meyer, C

    1997-04-01

    Higher plant nitrite reductase (NiR) is a monomeric chloroplastic protein catalysing the reduction of nitrite, the product of nitrate reduction, to ammonium. The expression of this enzyme is controlled at the transcriptional level by light and by the nitrogen source. In order to study the post-transcriptional regulation of NiR, Nicotiana plumbaginifolia and Arabidopsis thaliana were transformed with a chimaeric NiR construct containing the tobacco leaf NiR1 coding sequence driven by the CaMV 35S RNA promoter. Transformed plants did not show any phenotypic difference when compared with the wild-type, although they overexpressed NiR activity in the leaves. When these plants were grown in vitro on media containing either nitrate or ammonium as sole nitrogen source, NiR mRNA derived from transgene expression was constitutively expressed, whereas NiR activity and protein level were strongly reduced on ammonium-containing medium. These results suggest that, together with transcriptional control, post-transcriptional regulation by the nitrogen source is operating on NiR expression. This post-transcriptional regulation of tobacco leaf NiR1 expression was observed not only in the closely related species N. plumbaginifolia but also in the more distant species A. thaliana.

  17. At-TAX: a whole genome tiling array resource for developmental expression analysis and transcript identification in Arabidopsis thaliana

    PubMed Central

    Laubinger, Sascha; Zeller, Georg; Henz, Stefan R; Sachsenberg, Timo; Widmer, Christian K; Naouar, Naïra; Vuylsteke, Marnik; Schölkopf, Bernhard; Rätsch, Gunnar; Weigel, Detlef

    2008-01-01

    Gene expression maps for model organisms, including Arabidopsis thaliana, have typically been created using gene-centric expression arrays. Here, we describe a comprehensive expression atlas, Arabidopsis thaliana Tiling Array Express (At-TAX), which is based on whole-genome tiling arrays. We demonstrate that tiling arrays are accurate tools for gene expression analysis and identified more than 1,000 unannotated transcribed regions. Visualizations of gene expression estimates, transcribed regions, and tiling probe measurements are accessible online at the At-TAX homepage. PMID:18613972

  18. The predominantly selfing plant Arabidopsis thaliana experienced a recent reduction in transposable element abundance compared to its outcrossing relative Arabidopsis lyrata

    PubMed Central

    2012-01-01

    Background Transposable elements (TEs) are major contributors to genome evolution. One factor that influences their evolutionary dynamics is whether their host reproduces through selfing or through outcrossing. According to the recombinational spreading hypothesis, for instance, TEs can spread more easily in outcrossing species through recombination, and should thus be less abundant in selfing species. We here studied the distribution and evolutionary dynamics of TE families in the predominantly selfing plant Arabidopsis thaliana and its close outcrossing relative Arabidopsis lyrata on a genome-wide scale. We characterized differences in TE abundance between them and asked which, if any, existing hypotheses about TE abundances may explain these differences. Results We identified 1,819 TE families representing all known classes of TEs in both species, and found three times more copies in the outcrossing A. lyrata than in the predominantly selfing A. thaliana, as well as ten times more TE families unique to A. lyrata. On average, elements in A. lyrata are younger than elements in A. thaliana. In particular, A. thaliana shows a marked decrease in element number that occurred during the most recent 10% of the time interval since A. thaliana split from A. lyrata. This most recent period in the evolution of A. thaliana started approximately 500,000 years ago, assuming a splitting time of 5 million years ago, and coincides with the time at which predominant selfing originated. Conclusions Our results indicate that the mating system may be important for determining TE copy number, and that selfing species are likely to have fewer TEs. PMID:22313744

  19. Molecular signatures in Arabidopsis thaliana in response to insect attack and bacterial infection.

    PubMed

    Barah, Pankaj; Winge, Per; Kusnierczyk, Anna; Tran, Diem Hong; Bones, Atle M

    2013-01-01

    Under the threat of global climatic change and food shortages, it is essential to take the initiative to obtain a comprehensive understanding of common and specific defence mechanisms existing in plant systems for protection against different types of biotic invaders. We have implemented an integrated approach to analyse the overall transcriptomic reprogramming and systems-level defence responses in the model plant species Arabidopsis thaliana (A. thaliana henceforth) during insect Brevicoryne brassicae (B. brassicae henceforth) and bacterial Pseudomonas syringae pv. tomato strain DC3000 (P. syringae henceforth) attacks. The main aim of this study was to identify the attacker-specific and general defence response signatures in A. thaliana when attacked by phloem-feeding aphids or pathogenic bacteria. The obtained annotated networks of differentially expressed transcripts indicated that members of transcription factor families, such as WRKY, MYB, ERF, BHLH and bZIP, could be crucial for stress-specific defence regulation in Arabidopsis during aphid and P. syringae attack. The defence response pathways, signalling pathways and metabolic processes associated with aphid attack and P. syringae infection partially overlapped. Components of several important biosynthesis and signalling pathways, such as salicylic acid (SA), jasmonic acid (JA), ethylene (ET) and glucosinolates, were differentially affected during the two the treatments. Several stress-regulated transcription factors were known to be associated with stress-inducible microRNAs. The differentially regulated gene sets included many signature transcription factors, and our co-expression analysis showed that they were also strongly co-expressed during 69 other biotic stress experiments. Defence responses and functional networks that were unique and specific to aphid or P. syringae stresses were identified. Furthermore, our analysis revealed a probable link between biotic stress and microRNAs in Arabidopsis and

  20. Natural genetic variation in Arabidopsis thaliana defense metabolism genes modulates field fitness.

    PubMed

    Kerwin, Rachel; Feusier, Julie; Corwin, Jason; Rubin, Matthew; Lin, Catherine; Muok, Alise; Larson, Brandon; Li, Baohua; Joseph, Bindu; Francisco, Marta; Copeland, Daniel; Weinig, Cynthia; Kliebenstein, Daniel J

    2015-04-13

    Natural populations persist in complex environments, where biotic stressors, such as pathogen and insect communities, fluctuate temporally and spatially. These shifting biotic pressures generate heterogeneous selective forces that can maintain standing natural variation within a species. To directly test if genes containing causal variation for the Arabidopsis thaliana defensive compounds, glucosinolates (GSL) control field fitness and are therefore subject to natural selection, we conducted a multi-year field trial using lines that vary in only specific causal genes. Interestingly, we found that variation in these naturally polymorphic GSL genes affected fitness in each of our environments but the pattern fluctuated such that highly fit genotypes in one trial displayed lower fitness in another and that no GSL genotype or genotypes consistently out-performed the others. This was true both across locations and within the same location across years. These results indicate that environmental heterogeneity may contribute to the maintenance of GSL variation observed within Arabidopsis thaliana.

  1. Archaic lineages broaden our view on the history of Arabidopsis thaliana.

    PubMed

    Fulgione, Andrea; Hancock, Angela M

    2018-06-04

    Contents I. II. III. IV. V. References SUMMARY: Natural variation in Arabidopsis thaliana has contributed to discoveries in diverse areas of plant biology. While A. thaliana has typically been considered a weed associated primarily with human-mediated environments, including agricultural and urban sites and railways, it has recently been shown that it is also native in remote natural areas, including high altitude sites in Eurasia and Africa, from the Atlas mountains in Morocco to the afro-alpine regions in Eastern and South Africa to Yunnan in China, the Himalayas and the Tibetan Plateau. This finding suggests that while A. thaliana has been extensively studied in Europe and Western Asia there are still many open questions about its population history, genotype-phenotype relationships and mechanisms of adaptation. © 2018 European Union New Phytologist © 2018 New Phytologist Trust.

  2. Sorbitol dehydrogenase is a cytosolic protein required for sorbitol metabolism in Arabidopsis thaliana.

    PubMed

    Aguayo, María Francisca; Ampuero, Diego; Mandujano, Patricio; Parada, Roberto; Muñoz, Rodrigo; Gallart, Marta; Altabella, Teresa; Cabrera, Ricardo; Stange, Claudia; Handford, Michael

    2013-05-01

    Sorbitol is converted to fructose in Rosaceae species by SORBITOL DEHYDROGENASE (SDH, EC 1.1.1.14), especially in sink organs. SDH has also been found in non-Rosaceae species and here we show that the protein encoded by At5g51970 in Arabidopsis thaliana (L.) Heynh. possesses the molecular characteristics of an SDH. Using a green fluorescent protein-tagged version and anti-SDH antisera, we determined that SDH is cytosolically localized, consistent with bioinformatic predictions. We also show that SDH is widely expressed, and that SDH protein accumulates in both source and sink organs. In the presence of NAD+, recombinant SDH exhibited greatest oxidative activity with sorbitol, ribitol and xylitol as substrates; other sugar alcohols were oxidized to a lesser extent. Under standard growth conditions, three independent sdh- mutants developed as wild-type. Nevertheless, all three exhibited reduced dry weight and primary root length compared to wild-type when grown in the presence of sorbitol. Additionally, under short-day conditions, the mutants were more resistant to dehydration stress, as shown by a reduced loss of leaf water content when watering was withheld, and a greater survival rate on re-watering. This evidence suggests that limitations in the metabolism of sugar alcohols alter the growth of Arabidopsis and its response to drought. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  3. Mutants in Arabidopsis thaliana with altered shoot gravitropism

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

    Bullen, B.L.; Poff, K.L.

    1987-04-01

    A procedure has been developed and used to screen 40,000 m-2 seedlings of Arabidopsis thaliana for strains with altered shoot gravitropism. Several strains have been identified for which shoot gravitropism is considerably more random than that of their wild-type parent (based on frequency distribution histograms of the gravitropic response to a 1 g stimulus). One such strain exhibits normal hypocotyl phototropism and normal root gravitropism. Thus, the gravitropism pathway in the shoot contains at least one mutable element which is not required for root gravitropism.

  4. Arabidopsis genotypes resistant and susceptible to diamondback moth (Lepidoptera: Putellidea): No net effects on insect growth

    USDA-ARS?s Scientific Manuscript database

    Plutella xylostella (L.), diamondback moth (DBM) is a destructive pest of the Brassicaceae including Arabidopsis thaliana (L.) Heynhold. Ecotypes of Arabidopsis vary in the amounts of leaf area consumed when fed on by DBM, which has been used as a measure of resistance to DBM. Recombinant inbred lin...

  5. Evaluation of the plant growth-promoting activity of Pseudomonas nitroreducens in Arabidopsis thaliana and Lactuca sativa.

    PubMed

    Trinh, Cao Son; Lee, Hyeri; Lee, Won Je; Lee, Seok Jin; Chung, Namhyun; Han, Juhyeong; Kim, Jongyun; Hong, Suk-Whan; Lee, Hojoung

    2018-06-01

    Pseudomonas nitroreducens: strain IHB B 13561 (PnIHB) enhances the growth of Arabidopsis thaliana and Lactuca sativa via the stimulation of cell development and nitrate absorption. Plant growth-promoting rhizobacteria (PGPR) enhance plant development through various mechanisms; they improve the uptake of soil resources by plants to greatly promote plant growth. Here, we used Arabidopsis thaliana seedlings and Lactuca sativa to screen the growth enhancement activities of a purified PGPR, Pseudomonas nitroreducens strain IHB B 13561 (PnIHB). When cocultivated with PnIHB, both species of plants exhibited notably improved growth, particularly in regard to biomass. Quantitative reverse transcription polymerase chain reaction analysis indicated high expression levels of the nitrate transporter genes, especially NRT2.1, which plays a major role in the high-affinity nitrate transport system in roots. Moreover, enhanced activity of the cyclin-B1 promoter was observed when wild-type 'Columbia-0' Arabidopsis seedlings were exposed to PnIHB, whereas upregulation of cyclin-B also occurred in the inoculated lettuce seedlings. Overall, these results suggest that PnIHB improves A. thaliana and L. sativa growth via specific pathways involved in the promotion of cell development and enhancement of nitrate uptake.

  6. 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

  7. In situ relationships between microbiota and potential pathobiota in Arabidopsis thaliana.

    PubMed

    Bartoli, Claudia; Frachon, Léa; Barret, Matthieu; Rigal, Mylène; Huard-Chauveau, Carine; Mayjonade, Baptiste; Zanchetta, Catherine; Bouchez, Olivier; Roby, Dominique; Carrère, Sébastien; Roux, Fabrice

    2018-05-30

    A current challenge in microbial pathogenesis is to identify biological control agents that may prevent and/or limit host invasion by microbial pathogens. In natura, hosts are often infected by multiple pathogens. However, most of the current studies have been performed under laboratory controlled conditions and by taking into account the interaction between a single commensal species and a single pathogenic species. The next step is therefore to explore the relationships between host-microbial communities (microbiota) and microbial members with potential pathogenic behavior (pathobiota) in a realistic ecological context. In the present study, we investigated such relationships within root-associated and leaf-associated bacterial communities of 163 ecologically contrasted Arabidopsis thaliana populations sampled across two seasons in southwest of France. In agreement with the theory of the invasion paradox, we observed a significant humped-back relationship between microbiota and pathobiota α-diversity that was robust between both seasons and plant organs. In most populations, we also observed a strong dynamics of microbiota composition between seasons. Accordingly, the potential pathobiota composition was explained by combinations of season-specific microbiota operational taxonomic units. This result suggests that the potential biomarkers controlling pathogen's invasion are highly dynamic.

  8. Combining growth-promoting genes leads to positive epistasis in Arabidopsis thaliana

    PubMed Central

    Vanhaeren, Hannes; Gonzalez, Nathalie; Coppens, Frederik; De Milde, Liesbeth; Van Daele, Twiggy; Vermeersch, Mattias; Eloy, Nubia B; Storme, Veronique; Inzé, Dirk

    2014-01-01

    Several genes positively influence final leaf size in Arabidopsis when mutated or overexpressed. The connections between these growth regulators are still poorly understood although such knowledge would further contribute to understand the processes driving leaf growth. In this study, we performed a combinatorial screen with 13 transgenic Arabidopsis lines with an increased leaf size. We found that from 61 analyzed combinations, 39% showed an additional increase in leaf size and most resulted from a positive epistasis on growth. Similar to what is found in other organisms in which such an epistasis assay was performed, only few genes were highly connected in synergistic combinations as we observed a positive epistasis in the majority of the combinations with samba, BRI1OE or SAUR19OE. Furthermore, positive epistasis was found with combinations of genes with a similar mode of action, but also with genes which affect distinct processes, such as cell proliferation and cell expansion. DOI: http://dx.doi.org/10.7554/eLife.02252.001 PMID:24843021

  9. Ethylene signaling triggered by low concentrations of ascorbic acid regulates biomass accumulation in Arabidopsis thaliana.

    PubMed

    Caviglia, M; Mazorra Morales, L M; Concellón, A; Gergoff Grozeff, G E; Wilson, M; Foyer, C H; Bartoli, C G

    2018-02-02

    Ascorbic acid (AA) is a major redox buffer in plant cells. The role of ethylene in the redox signaling pathways that influence photosynthesis and growth was explored in two independent AA deficient Arabidopsis thaliana mutants (vtc2-1 and vtc2-4). Both mutants, which are defective in the AA biosynthesis gene GDP-L-galactose phosphorylase, produce higher amounts of ethylene than wt plants. In contrast to the wt, the inhibition of ethylene signaling increased leaf conductance, photosynthesis and dry weight in both vtc2 mutant lines. The AA-deficient mutants showed altered expression of genes encoding proteins involved in the synthesis/responses to phytohormones that control growth, particularly auxin, cytokinins, abscisic acid, brassinosterioids, ethylene and salicylic acid. These results demonstrate that AA deficiency modifies hormone signaling in plants, redox-ethylene interactions providing a regulatory node controlling shoot biomass accumulation. Copyright © 2018 Elsevier Inc. All rights reserved.

  10. Induction of stromule formation by extracellular sucrose and glucose in epidermal leaf tissue of Arabidopsis thaliana

    PubMed Central

    2011-01-01

    Background Stromules are dynamic tubular structures emerging from the surface of plastids that are filled with stroma. Despite considerable progress in understanding the importance of certain cytoskeleton elements and motor proteins for stromule maintenance, their function within the plant cell is still unknown. It has been suggested that stromules facilitate the exchange of metabolites and/or signals between plastids and other cell compartments by increasing the cytosolically exposed plastid surface area but experimental evidence for the involvement of stromules in metabolic processes is not available. The frequent occurrence of stromules in both sink tissues and heterotrophic cell cultures suggests that the presence of carbohydrates in the extracellular space is a possible trigger of stromule formation. We have examined this hypothesis with induction experiments using the upper epidermis from rosette leaves of Arabidopsis thaliana as a model system. Results We found that the stromule frequency rises significantly if either sucrose or glucose is applied to the apoplast by vacuum infiltration. In contrast, neither fructose nor sorbitol or mannitol are capable of inducing stromule formation which rules out the hypothesis that stromule induction is merely the result of changes in the osmotic conditions. Stromule formation depends on translational activity in the cytosol, whereas protein synthesis within the plastids is not required. Lastly, stromule induction is not restricted to the plastids of the upper epidermis but is similarly observed also with chloroplasts of the palisade parenchyma. Conclusions The establishment of an experimental system allowing the reproducible induction of stromules by vacuum infiltration of leaf tissue provides a suitable tool for the systematic analysis of conditions and requirements leading to the formation of these dynamic organelle structures. The applicability of the approach is demonstrated here by analyzing the influence of

  11. An oilseed rape WRKY-type transcription factor regulates ROS accumulation and leaf senescence in Nicotiana benthamiana and Arabidopsis through modulating transcription of RbohD and RbohF.

    PubMed

    Yang, Liu; Ye, Chaofei; Zhao, Yuting; Cheng, Xiaolin; Wang, Yiqiao; Jiang, Yuan-Qing; Yang, Bo

    2018-06-01

    Overexpression of BnaWGR1 causes ROS accumulation and promotes leaf senescence. BnaWGR1 binds to promoters of RbohD and RbohF and regulates their expression. Manipulation of leaf senescence process affects agricultural traits of crop plants, including biomass, seed yield and stress resistance. Since delayed leaf senescence usually enhances tolerance to multiple stresses, we analyzed the function of specific MAPK-WRKY cascades in abiotic and biotic stress tolerance as well as leaf senescence in oilseed rape (Brassica napus L.), one of the important oil crops. In the present study, we showed that expression of one WRKY gene from oilseed rape, BnaWGR1, induced an accumulation of reactive oxygen species (ROS), cell death and precocious leaf senescence both in Nicotiana benthamiana and transgenic Arabidopsis (Arabidopsis thaliana). BnaWGR1 regulates the transcription of two genes encoding key enzymes implicated in production of ROS, that is, respiratory burst oxidase homolog (Rboh) D and RbohF. A dual-luciferase reporter assay confirmed the transcriptional regulation of RbohD and RbohF by BnaWGR1. In vitro electrophoresis mobility shift assay (EMSA) showed that BnaWGR1 could bind to W-box cis-elements within promoters of RbohD and RbohF. Moreover, RbohD and RbohF were significantly upregulated in transgenic Arabidopsis overexpressing BnaWGR1. In summary, these results suggest that BnaWGR1 could positively regulate leaf senescence through regulating the expression of RbohD and RbohF genes.

  12. Characterization of the Arabidopsis thaliana 2-Cys peroxiredoxin interactome.

    PubMed

    Cerveau, Delphine; Kraut, Alexandra; Stotz, Henrik U; Mueller, Martin J; Couté, Yohann; Rey, Pascal

    2016-11-01

    Peroxiredoxins are ubiquitous thiol-dependent peroxidases for which chaperone and signaling roles have been reported in various types of organisms in recent years. In plants, the peroxidase function of the two typical plastidial 2-Cys peroxiredoxins (2-Cys PRX A and B) has been highlighted while the other functions, particularly in ROS-dependent signaling pathways, are still elusive notably due to the lack of knowledge of interacting partners. Using an ex vivo approach based on co-immunoprecipitation of leaf extracts from Arabidopsis thaliana wild-type and mutant plants lacking 2-Cys PRX expression followed by mass spectrometry-based proteomics, 158 proteins were found associated with 2-Cys PRXs. Already known partners like thioredoxin-related electron donors (Chloroplastic Drought-induced Stress Protein of 32kDa, Atypical Cysteine Histidine-rich Thioredoxin 2) and enzymes involved in chlorophyll synthesis (Protochlorophyllide OxidoReductase B) or carbon metabolism (Fructose-1,6-BisPhosphatase) were identified, validating the relevance of the approach. Bioinformatic and bibliographic analyses allowed the functional classification of the identified proteins and revealed that more than 40% are localized in plastids. The possible roles of plant 2-Cys PRXs in redox signaling pathways are discussed in relation with the functions of the potential partners notably those involved in redox homeostasis, carbon and amino acid metabolisms as well as chlorophyll biosynthesis. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  13. Exaggerated root respiration accounts for growth retardation in a starchless mutant of Arabidopsis thaliana.

    PubMed

    Brauner, Katrin; Hörmiller, Imke; Nägele, Thomas; Heyer, Arnd G

    2014-07-01

    The knock-out mutation of plastidial phosphoglucomutase (pgm) causes a starchless phenotype in Arabidopsis thaliana, and results in a severe growth reduction of plants cultivated under diurnal conditions. It has been speculated that high soluble sugar levels accumulating during the light phase in leaf mesophyll might cause a reduction of photosynthetic activity or that shortage of reduced carbon during the night is the reason for the slow biomass gain of pgm. Separate simultaneous measurements of leaf net photosynthesis and root respiration demonstrate that photosynthetic activity per unit fresh weight is not reduced in pgm, whereas root respiration is strongly elevated. Comparison with a mutant defective in the dominating vacuolar invertase (AtβFruct4) revealed that high sucrose concentration in the cytosol, but not in the vacuole, of leaf cells is responsible for elevated assimilate transport to the root. Increased sugar supply to the root, as observed in pgm mutants, forces substantial respiratory losses. Because root respiration accounts for 80% of total plant respiration under long-day conditions, this gives rise to retarded biomass formation. In contrast, reduced vacuolar invertase activity leads to reduced net photosynthesis in the shoot and lowered root respiration, and affords an increased root/shoot ratio. The results demonstrate that roots have very limited capacity for carbon storage but exert rigid control of supply for their maintenance metabolism. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

  14. Leaf phenomics: a systematic reverse genetic screen for Arabidopsis leaf mutants.

    PubMed

    Wilson-Sánchez, David; Rubio-Díaz, Silvia; Muñoz-Viana, Rafael; Pérez-Pérez, José Manuel; Jover-Gil, Sara; Ponce, María Rosa; Micol, José Luis

    2014-09-01

    The study and eventual manipulation of leaf development in plants requires a thorough understanding of the genetic basis of leaf organogenesis. Forward genetic screens have identified hundreds of Arabidopsis mutants with altered leaf development, but the genome has not yet been saturated. To identify genes required for leaf development we are screening the Arabidopsis Salk Unimutant collection. We have identified 608 lines that exhibit a leaf phenotype with full penetrance and almost constant expressivity and 98 additional lines with segregating mutant phenotypes. To allow indexing and integration with other mutants, the mutant phenotypes were described using a custom leaf phenotype ontology. We found that the indexed mutation is present in the annotated locus for 78% of the 553 mutants genotyped, and that in half of these the annotated T-DNA is responsible for the phenotype. To quickly map non-annotated T-DNA insertions, we developed a reliable, cost-effective and easy method based on whole-genome sequencing. To enable comprehensive access to our data, we implemented a public web application named PhenoLeaf (http://genetics.umh.es/phenoleaf) that allows researchers to query the results of our screen, including text and visual phenotype information. We demonstrated how this new resource can facilitate gene function discovery by identifying and characterizing At1g77600, which we found to be required for proximal-distal cell cycle-driven leaf growth, and At3g62870, which encodes a ribosomal protein needed for cell proliferation and chloroplast function. This collection provides a valuable tool for the study of leaf development, characterization of biomass feedstocks and examination of other traits in this fundamental photosynthetic organ. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

  15. Antiphase light and temperature cycles affect PHYTOCHROME B-controlled ethylene sensitivity and biosynthesis, limiting leaf movement and growth of Arabidopsis.

    PubMed

    Bours, Ralph; van Zanten, Martijn; Pierik, Ronald; Bouwmeester, Harro; van der Krol, Alexander

    2013-10-01

    In the natural environment, days are generally warmer than the night, resulting in a positive day/night temperature difference (+DIF). Plants have adapted to these conditions, and when exposed to antiphase light and temperature cycles (cold photoperiod/warm night [-DIF]), most species exhibit reduced elongation growth. To study the physiological mechanism of how light and temperature cycles affect plant growth, we used infrared imaging to dissect growth dynamics under +DIF and -DIF in the model plant Arabidopsis (Arabidopsis thaliana). We found that -DIF altered leaf growth patterns, decreasing the amplitude and delaying the phase of leaf movement. Ethylene application restored leaf growth in -DIF conditions, and constitutive ethylene signaling mutants maintain robust leaf movement amplitudes under -DIF, indicating that ethylene signaling becomes limiting under these conditions. In response to -DIF, the phase of ethylene emission advanced 2 h, but total ethylene emission was not reduced. However, expression analysis on members of the 1-aminocyclopropane-1-carboxylic acid (ACC) synthase ethylene biosynthesis gene family showed that ACS2 activity is specifically suppressed in the petiole region under -DIF conditions. Indeed, petioles of plants under -DIF had reduced ACC content, and application of ACC to the petiole restored leaf growth patterns. Moreover, acs2 mutants displayed reduced leaf movement under +DIF, similar to wild-type plants under -DIF. In addition, we demonstrate that the photoreceptor PHYTOCHROME B restricts ethylene biosynthesis and constrains the -DIF-induced phase shift in rhythmic growth. Our findings provide a mechanistic insight into how fluctuating temperature cycles regulate plant growth.

  16. Transcriptome analysis of intraspecific competition in Arabidopsis thaliana reveals organ-specific signatures related to nutrient acquisition and general stress response pathways

    PubMed Central

    2012-01-01

    Background Plants are sessile and therefore have to perceive and adjust to changes in their environment. The presence of neighbours leads to a competitive situation where resources and space will be limited. Complex adaptive responses to such situation are poorly understood at the molecular level. Results Using microarrays, we analysed whole-genome expression changes in Arabidopsis thaliana plants subjected to intraspecific competition. The leaf and root transcriptome was strongly altered by competition. Differentially expressed genes were enriched in genes involved in nutrient deficiency (mainly N, P, K), perception of light quality, and responses to abiotic and biotic stresses. Interestingly, performance of the generalist insect Spodoptera littoralis on densely grown plants was significantly reduced, suggesting that plants under competition display enhanced resistance to herbivory. Conclusions This study provides a comprehensive list of genes whose expression is affected by intraspecific competition in Arabidopsis. The outcome is a unique response that involves genes related to light, nutrient deficiency, abiotic stress, and defence responses. PMID:23194435

  17. Identification of lipopolysaccharide-interacting plasma membrane-type proteins in Arabidopsis thaliana.

    PubMed

    Vilakazi, Cornelius S; Dubery, Ian A; Piater, Lizelle A

    2017-02-01

    Lipopolysaccharide (LPS) is an amphiphatic bacterial glycoconjugate found on the external membrane of Gram-negative bacteria. This endotoxin is considered as a microbe-associated molecular pattern (MAMP) molecule and has been shown to elicit defense responses in plants. Here, LPS-interacting proteins from Arabidopsis thaliana plasma membrane (PM)-type fractions were captured and identified in order to investigate those involved in LPS perception and linked to triggering of innate immune responses. A novel proteomics-based affinity-capture strategy coupled to liquid chromatography-tandem mass spectrometry (LC-MS/MS) was employed for the enrichment and identification of LPS-interacting proteins. As such, LPS isolated from Burkholderia cepacia (LPS B.cep. ) was immobilized on three independent and distinct affinity-based matrices to serve as bait for interacting proteins from A. thaliana leaf and callus tissue. These were resolved by 1D electrophoresis and identified by mass spectrometry. Proteins specifically bound to LPS B.cep. have been implicated in membrane structure (e.g. COBRA-like and tubulin proteins), membrane trafficking and/or transport (e.g. soluble NSF attachment protein receptor (SNARE) proteins, patellin, aquaporin, PM instrinsic proteins (PIP) and H + -ATPase), signal transduction (receptor-like kinases and calcium-dependent protein kinases) as well as defense/stress responses (e.g. hypersensitive-induced response (HIR) proteins, jacalin-like lectin domain-containing protein and myrosinase-binding proteins). The novel affinity-capture strategy for the enrichment of LPS-interacting proteins proved to be effective, especially in the binding of proteins involved in plant defense responses, and can thus be used to elucidate LPS-mediated molecular recognition and disease mechanism(s). Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  18. Multi-Element Bioimaging of Arabidopsis thaliana Roots.

    PubMed

    Persson, Daniel Pergament; Chen, Anle; Aarts, Mark G M; Salt, David E; Schjoerring, Jan K; Husted, Søren

    2016-10-01

    Better understanding of root function is central for the development of plants with more efficient nutrient uptake and translocation. We here present a method for multielement bioimaging at the cellular level in roots of the genetic model system Arabidopsis (Arabidopsis thaliana). Using conventional protocols for microscopy, we observed that diffusible ions such as potassium and sodium were lost during sample dehydration. Thus, we developed a protocol that preserves ions in their native, cellular environment. Briefly, fresh roots are encapsulated in paraffin, cryo-sectioned, and freeze dried. Samples are finally analyzed by laser ablation-inductively coupled plasma-mass spectrometry, utilizing a specially designed internal standard procedure. The method can be further developed to maintain the native composition of proteins, enzymes, RNA, and DNA, making it attractive in combination with other omics techniques. To demonstrate the potential of the method, we analyzed a mutant of Arabidopsis unable to synthesize the metal chelator nicotianamine. The mutant accumulated substantially more zinc and manganese than the wild type in the tissues surrounding the vascular cylinder. For iron, the images looked completely different, with iron bound mainly in the epidermis of the wild-type plants but confined to the cortical cell walls of the mutant. The method offers the power of inductively coupled plasma-mass spectrometry to be fully employed, thereby providing a basis for detailed studies of ion transport in roots. Being applicable to Arabidopsis, the molecular and genetic approaches available in this system can now be fully exploited in order to gain a better mechanistic understanding of these processes. © 2016 American Society of Plant Biologists. All Rights Reserved.

  19. A functional genomic analysis of Arabidopsis thaliana PP2C clade D

    USDA-ARS?s Scientific Manuscript database

    In the reference dicot plant Arabidopsis thaliana, the PP2C family of P-protein phosphatases includes the products of 80 genes that have been separated into 10 multi-protein clades plus six singletons. Clade D includes the products of nine genes distributed among 3 chromosomes (PPD1, At3g12620; PPD2...

  20. Transgenerational changes in plant physiology and in transposon expression in response to UV-C stress in Arabidopsis thaliana

    PubMed Central

    Migicovsky, Zoe; Kovalchuk, Igor

    2014-01-01

    Stress has a negative impact on crop yield by altering a gain in biomass and affecting seed set. Recent reports suggest that exposure to stress also influences the response of the progeny. In this paper, we analyzed seed size, leaf size, bolting time and transposon expression in 2 consecutive generations of Arabidopsis thaliana plants exposed to moderate UV-C stress. Since previous reports suggested a potential role of Dicer-like (DCL) proteins in the establishment of transgenerational response, we used dcl2, dcl3 and dcl4 mutants in parallel with wild-type plants. These studies revealed that leaf number decreased in the progeny of UV-C stressed plants, and bolting occurred later. Transposons were also re-activated in the progeny of stressed plants. Changes in the dcl mutants were less prominent than in wild-type plants. DCL2 and DCL3 appeared to be more important in the transgenerational stress memory than DCL4 because transgenerational changes were less profound in the dcl2 and dcl3 mutants. PMID:25482751

  1. Transgenerational changes in plant physiology and in transposon expression in response to UV-C stress in Arabidopsis thaliana.

    PubMed

    Migicovsky, Zoe; Kovalchuk, Igor

    2014-01-01

    Stress has a negative impact on crop yield by altering a gain in biomass and affecting seed set. Recent reports suggest that exposure to stress also influences the response of the progeny. In this paper, we analyzed seed size, leaf size, bolting time and transposon expression in 2 consecutive generations of Arabidopsis thaliana plants exposed to moderate UV-C stress. Since previous reports suggested a potential role of Dicer-like (DCL) proteins in the establishment of transgenerational response, we used dcl2, dcl3 and dcl4 mutants in parallel with wild-type plants. These studies revealed that leaf number decreased in the progeny of UV-C stressed plants, and bolting occurred later. Transposons were also re-activated in the progeny of stressed plants. Changes in the dcl mutants were less prominent than in wild-type plants. DCL2 and DCL3 appeared to be more important in the transgenerational stress memory than DCL4 because transgenerational changes were less profound in the dcl2 and dcl3 mutants.

  2. Phenotypical and molecular responses of Arabidopsis thaliana roots as a result of inoculation with the auxin-producing bacterium Azospirillum brasilense.

    PubMed

    Spaepen, Stijn; Bossuyt, Stijn; Engelen, Kristof; Marchal, Kathleen; Vanderleyden, Jos

    2014-02-01

    The auxin-producing bacterium Azospirillum brasilense Sp245 can promote the growth of several plant species. The model plant Arabidopsis thaliana was chosen as host plant to gain an insight into the molecular mechanisms that govern this interaction. The determination of differential gene expression in Arabidopsis roots after inoculation with either A. brasilense wild-type or an auxin biosynthesis mutant was achieved by microarray analysis. Arabidopsis thaliana inoculation with A. brasilense wild-type increases the number of lateral roots and root hairs, and elevates the internal auxin concentration in the plant. The A. thaliana root transcriptome undergoes extensive changes on A. brasilense inoculation, and the effects are more pronounced at later time points. The wild-type bacterial strain induces changes in hormone- and defense-related genes, as well as in plant cell wall-related genes. The A. brasilense mutant, however, does not elicit these transcriptional changes to the same extent. There are qualitative and quantitative differences between A. thaliana responses to the wild-type A. brasilense strain and the auxin biosynthesis mutant strain, based on both phenotypic and transcriptomic data. This illustrates the major role played by auxin in the Azospirillum-Arabidopsis interaction, and possibly also in other bacterium-plant interactions. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  3. Differentially enhanced insect resistance, at a cost, in Arabidopsis thaliana constitutively expressing a transcription factor of defensive metabolites.

    PubMed

    Johnson, Eric T; Dowd, Patrick F

    2004-08-11

    A transgenic line of Arabidopsis thaliana constitutively expressing a conserved MYB transcription factor of phenylpropanoid biosynthesis resulting in solid-purple leaves had significantly increased resistance to leaf feeding by first instar fall armyworms (Spodoptera frugiperda), but no enhanced resistance to cabbage looper (Trichoplusia ni) larvae, when compared to wild type plants. However, inflorescence and silique (seed pod) production were significantly reduced by 22 and 52%, respectively, in the transgenic line compared to wild type plants. Reduction in feeding by S. frugiperda was significantly positively correlated with reduction in weights of survivors, but both were negatively correlated with the concentration of anthocyanins. These results indicate that a single gene regulator can activate a defensive pathway sufficient to produce increased resistance to insects but that this activation confers a cost in plant productivity.

  4. 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.; hide

    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.

  5. A rapid total reflection X-ray fluorescence protocol for micro analyses of ion profiles in Arabidopsis thaliana

    NASA Astrophysics Data System (ADS)

    Höhner, Ricarda; Tabatabaei, Samaneh; Kunz, Hans-Henning; Fittschen, Ursula

    2016-11-01

    The ion homeostasis of macro and micronutrients in plant cells and tissues is a fundamental requirement for vital biochemical pathways including photosynthesis. In nature, ion homeostasis is affected mainly by three processes: 1. Environmental stress factors, 2. Developmental effects, and 3. Loss or gain-of-function mutations in the plant genome. Here we present a rapid total reflection X-ray fluorescence (TXRF) protocol that allows for simultaneous quantification of several elements such as potassium (K), calcium (Ca), sulfur (S), manganese (Mn) and strontium (Sr) in Arabidopsis thaliana leaf specimens. Our procedure is cost-efficient and enables precise, robust and highly reproducible measurements on tissue samples as small as 0.3 mg dry weight. As shown here, we apply the TXRF procedure to detect accurately the early replacement of K by Na ions in leaves of plants exposed to soil salinity, a globally increasing abiotic stress factor. Furthermore, we were able to prove the existence of a leaf development-dependent ion gradient for K, Ca, and other divalent ions in A. thaliana; i.e. old leaves contain significantly lower K but higher Ca than young leaves. Lastly, we show that our procedure can be readily applied to reveal subtle differences in tissue-specific ion contents of plant mutants. We employed independent A. thaliana kea1kea2 loss-of-function mutants that lack KEA1 and KEA2, two highly active chloroplast K exchange proteins. We found significantly increased K levels specifically in kea1kea2 mutants, i.e. 55 mg ∗ g- 1 dry weight, compared to 40 mg ∗ g- 1 dry weight in wild type plants. The TXRF procedure can be supplemented with Flame atomic absorption (FAAS) and emission spectrometry (FAES) to expand the detection range to sodium (Na) and magnesium (Mg). Because of the small sample amounts required, this method is especially suited to probe individual leaves in single plants or even specific leaf areas. Therefore, TXRF represents a powerful method to

  6. Adaptation of Arabidopsis thaliana to the Yangtze River basin.

    PubMed

    Zou, Yu-Pan; Hou, Xing-Hui; Wu, Qiong; Chen, Jia-Fu; Li, Zi-Wen; Han, Ting-Shen; Niu, Xiao-Min; Yang, Li; Xu, Yong-Chao; Zhang, Jie; Zhang, Fu-Min; Tan, Dunyan; Tian, Zhixi; Gu, Hongya; Guo, Ya-Long

    2017-12-28

    Organisms need to adapt to keep pace with a changing environment. Examining recent range expansion aids our understanding of how organisms evolve to overcome environmental constraints. However, how organisms adapt to climate changes is a crucial biological question that is still largely unanswered. The plant Arabidopsis thaliana is an excellent system to study this fundamental question. Its origin is in the Iberian Peninsula and North Africa, but it has spread to the Far East, including the most south-eastern edge of its native habitats, the Yangtze River basin, where the climate is very different. We sequenced 118 A. thaliana strains from the region surrounding the Yangtze River basin. We found that the Yangtze River basin population is a unique population and diverged about 61,409 years ago, with gene flows occurring at two different time points, followed by a population dispersion into the Yangtze River basin in the last few thousands of years. Positive selection analyses revealed that biological regulation processes, such as flowering time, immune and defense response processes could be correlated with the adaptation event. In particular, we found that the flowering time gene SVP has contributed to A. thaliana adaptation to the Yangtze River basin based on genetic mapping. A. thaliana adapted to the Yangtze River basin habitat by promoting the onset of flowering, a finding that sheds light on how a species can adapt to locales with very different climates.

  7. The Arabidopsis thaliana aquaporin AtPIP1;2 is a physiologically relevant CO₂ transport facilitator.

    PubMed

    Heckwolf, Marlies; Pater, Dianne; Hanson, David T; Kaldenhoff, Ralf

    2011-09-01

    Cellular exchange of carbon dioxide (CO₂) is of extraordinary importance for life. Despite this significance, its molecular mechanisms are still unclear and a matter of controversy. In contrast to other living organisms, plants are physiologically limited by the availability of CO₂. In most plants, net photosynthesis is directly dependent on CO₂ diffusion from the atmosphere to the chloroplast. Thus, it is important to analyze CO₂ transport with regards to its effect on photosynthesis. A mutation of the Arabidopsis thaliana AtPIP1;2 gene, which was characterized as a non-water transporting but CO₂ transport-facilitating aquaporin in heterologous expression systems, correlated with a reduction in photosynthesis under a wide range of atmospheric CO₂ concentrations. Here, we could demonstrate that the effect was caused by reduced CO₂ conductivity in leaf tissue. It is concluded that the AtPIP1;2 gene product limits CO₂ diffusion and photosynthesis in leaves. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.

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

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

    Noir, Sandra; Braeutigam, Anne; Colby, Thomas

    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 themore » identified proteins are discussed in relation to the pollen transcriptome and the full protein complement encoded by the nuclear Arabidopsis genome.« less

  9. Stochastic gene expression in Arabidopsis thaliana.

    PubMed

    Araújo, Ilka Schultheiß; Pietsch, Jessica Magdalena; Keizer, Emma Mathilde; Greese, Bettina; Balkunde, Rachappa; Fleck, Christian; Hülskamp, Martin

    2017-12-14

    Although plant development is highly reproducible, some stochasticity exists. This developmental stochasticity may be caused by noisy gene expression. Here we analyze the fluctuation of protein expression in Arabidopsis thaliana. Using the photoconvertible KikGR marker, we show that the protein expressions of individual cells fluctuate over time. A dual reporter system was used to study extrinsic and intrinsic noise of marker gene expression. We report that extrinsic noise is higher than intrinsic noise and that extrinsic noise in stomata is clearly lower in comparison to several other tissues/cell types. Finally, we show that cells are coupled with respect to stochastic protein expression in young leaves, hypocotyls and roots but not in mature leaves. Our data indicate that stochasticity of gene expression can vary between tissues/cell types and that it can be coupled in a non-cell-autonomous manner.

  10. Characterization of the yeast copper-inducible promoter system in Arabidopsis thaliana

    NASA Technical Reports Server (NTRS)

    Granger, C. L.; Cyr, R. J.

    2001-01-01

    Inducible promoters or gene-switches are used to both spatially and temporally regulate gene expression. Such regulation can provide information concerning the function of a gene in a developmental context as well as avoid potential harmful effects due to overexpression. A gfp construct under the control of a copper-inducible promoter was introduced into Arabidopsis thaliana (L.) Heynh. and the regulatory parameters of this inducible promoter were determined. Here, we describe the time-course of up- and down-regulation of GFP expression in response to copper level, the optimal regulatory levels of copper, and the tissue specificity of expression in three transgenic lines. We conclude that the copper-inducible promoter system may be useful in regulating the time and location of gene expression in A. thaliana.

  11. A Cold-Inducible DEAD-Box RNA Helicase from Arabidopsis thaliana Regulates Plant Growth and Development under Low Temperature.

    PubMed

    Liu, Yuelin; Tabata, Daisuke; Imai, Ryozo

    2016-01-01

    DEAD-box RNA helicases comprise a large family and are involved in a range of RNA processing events. Here, we identified one of the Arabidopsis thaliana DEAD-box RNA helicases, AtRH7, as an interactor of Arabidopsis COLD SHOCK DOMAIN PROTEIN 3 (AtCSP3), which is an RNA chaperone involved in cold adaptation. Promoter:GUS transgenic plants revealed that AtRH7 is expressed ubiquitously and that its levels of the expression are higher in rapidly growing tissues. Knockout mutant lines displayed several morphological alterations such as disturbed vein pattern, pointed first true leaves, and short roots, which resemble ribosome-related mutants of Arabidopsis. In addition, aberrant floral development was also observed in rh7 mutants. When the mutants were germinated at low temperature (12°C), both radicle and first leaf emergence were severely delayed; after exposure of seedlings to a long period of cold, the mutants developed aberrant, fewer, and smaller leaves. RNA blots and circular RT-PCR revealed that 35S and 18S rRNA precursors accumulated to higher levels in the mutants than in WT under both normal and cold conditions, suggesting the mutants are partially impaired in pre-rRNA processing. Taken together, the results suggest that AtRH7 affects rRNA biogenesis and plays an important role in plant growth under cold.

  12. Volatile-Mediated Effects Predominate in Paraburkholderia phytofirmans Growth Promotion and Salt Stress Tolerance of Arabidopsis thaliana

    PubMed Central

    Ledger, Thomas; Rojas, Sandy; Timmermann, Tania; Pinedo, Ignacio; Poupin, María J.; Garrido, Tatiana; Richter, Pablo; Tamayo, Javier

    2016-01-01

    Abiotic stress has a growing impact on plant growth and agricultural activity worldwide. Specific plant growth promoting rhizobacteria have been reported to stimulate growth and tolerance to abiotic stress in plants, and molecular mechanisms like phytohormone synthesis and 1-aminocyclopropane-1-carboxylate deamination are usual candidates proposed to mediate these bacterial effects. Paraburkholderia phytofirmans PsJN is able to promote growth of several plant hosts, and improve their tolerance to chilling, drought and salinity. This work investigated bacterial determinants involved in PsJN stimulation of growth and salinity tolerance in Arabidopsis thaliana, showing bacteria enable plants to survive long-term salinity treatment, accumulating less sodium within leaf tissues relative to non-inoculated controls. Inactivation of specific bacterial genes encoding ACC deaminase, auxin catabolism, N-acyl-homoserine-lactone production, and flagellin synthesis showed these functions have little influence on bacterial induction of salinity tolerance. Volatile organic compound emission from strain PsJN was shown to reproduce the effects of direct bacterial inoculation of roots, increasing plant growth rate and tolerance to salinity evaluated both in vitro and in soil. Furthermore, early exposure to VOCs from P. phytofirmans was sufficient to stimulate long-term effects observed in Arabidopsis growth in the presence and absence of salinity. Organic compounds were analyzed in the headspace of PsJN cultures, showing production of 2-undecanone, 7-hexanol, 3-methylbutanol and dimethyl disulfide. Exposure of A. thaliana to different quantities of these molecules showed that they are able to influence growth in a wide range of added amounts. Exposure to a blend of the first three compounds was found to mimic the effects of PsJN on both general growth promotion and salinity tolerance. To our knowledge, this is the first report on volatile compound-mediated induction of plant abiotic

  13. Arabidopsis thaliana as a model species for xylem hydraulics: does size matter?

    PubMed Central

    Tixier, Aude; Cochard, Hervé; Badel, Eric; Dusotoit-Coucaud, Anaïs; Jansen, Steven; Herbette, Stéphane

    2013-01-01

    While Arabidopsis thaliana has been proposed as a model species for wood development, the potential of this tiny herb for studying xylem hydraulics remains unexplored and anticipated by scepticism. Inflorescence stems of A. thaliana were used to measure hydraulic conductivity and cavitation resistance, whereas light and electron microscopy allowed observations of vessels. In wild-type plants, measured and theoretical conductivity showed a significant correlation (R 2 = 0.80, P < 0.01). Moreover, scaling of vessel dimensions and intervessel pit structure of A. thaliana were consistent with structure–function relationships of woody plants. The reliability and resolution of the hydraulic methods applied to measure vulnerability to cavitation were addressed by comparing plants grown under different photoperiods or different mutant lines. Sigmoid vulnerability curves of A. thaliana indicated a pressure corresponding to 50% loss of hydraulic conductance (P 50) between –3 and –2.5MPa for short-day and long-day plants, respectively. Polygalacturonase mutants showed a higher P 50 value (–2.25MPa), suggesting a role for pectins in vulnerability to cavitation. The application of A. thaliana as a model species for xylem hydraulics provides exciting possibilities for (1) exploring the molecular basis of xylem anatomical features and (2) understanding genetic mechanisms behind xylem functional traits such as cavitation resistance. Compared to perennial woody species, however, the lesser amount of xylem in A. thaliana has its limitations. PMID:23547109

  14. Arabidopsis thaliana as a model species for xylem hydraulics: does size matter?

    PubMed

    Tixier, Aude; Cochard, Hervé; Badel, Eric; Dusotoit-Coucaud, Anaïs; Jansen, Steven; Herbette, Stéphane

    2013-05-01

    While Arabidopsis thaliana has been proposed as a model species for wood development, the potential of this tiny herb for studying xylem hydraulics remains unexplored and anticipated by scepticism. Inflorescence stems of A. thaliana were used to measure hydraulic conductivity and cavitation resistance, whereas light and electron microscopy allowed observations of vessels. In wild-type plants, measured and theoretical conductivity showed a significant correlation (R (2) = 0.80, P < 0.01). Moreover, scaling of vessel dimensions and intervessel pit structure of A. thaliana were consistent with structure-function relationships of woody plants. The reliability and resolution of the hydraulic methods applied to measure vulnerability to cavitation were addressed by comparing plants grown under different photoperiods or different mutant lines. Sigmoid vulnerability curves of A. thaliana indicated a pressure corresponding to 50% loss of hydraulic conductance (P 50) between -3 and -2.5MPa for short-day and long-day plants, respectively. Polygalacturonase mutants showed a higher P 50 value (-2.25MPa), suggesting a role for pectins in vulnerability to cavitation. The application of A. thaliana as a model species for xylem hydraulics provides exciting possibilities for (1) exploring the molecular basis of xylem anatomical features and (2) understanding genetic mechanisms behind xylem functional traits such as cavitation resistance. Compared to perennial woody species, however, the lesser amount of xylem in A. thaliana has its limitations.

  15. The role of nitric oxide in the interaction of Arabidopsis thaliana with the biotrophic fungi, Golovinomyces orontii and Erysiphe pisi

    PubMed Central

    Schlicht, Markus; Kombrink, Erich

    2013-01-01

    Powdery mildews are a diverse group of pathogenic fungi that can infect a large number of plant species, including many economically important crops. However, basic and applied research on these devastating diseases has been hampered by the obligate biotrophic lifestyle of the pathogens, which require living host cells for growth and reproduction, and lacking genetic and molecular tools for important host plants. The establishment of Arabidopsis thaliana as a host of different powdery mildew species allowed pursuing new strategies to study the molecular mechanisms governing these complex plant–pathogen interactions. Nitric oxide (NO) has emerged as an important signaling molecule in plants, which is produced upon infection and involved in activation of plant immune responses. However, the source and pathway of NO production and its precise function in the regulatory network of reactions leading to resistance is still unknown. We studied the response of Arabidopsis thaliana to infection with the adapted powdery mildew, Golovinomyces orontii (compatible interaction) and the non-adapted, Erysiphe pisi (incompatible interaction). We observed that NO accumulated rapidly and transiently at infection sites and we established a correlation between the resistance phenotype and the amount and timing of NO production. Arabidopsis mutants with defective immune response accumulated lower NO levels compared to wild type. Conversely, increased NO levels, generated by treatment with chemicals or expression of a NO-synthesizing enzyme, resulted in enhanced resistance, but only sustained NO production prevented excessive leaf colonization by the fungus, which was not achieved by a short NO burst although this reduced the initial penetration success. By contrast, lowered NO levels did not impair the ultimate resistance phenotype. Although our results suggest a function of NO in mediating plant immune responses, a direct impact on pathogen growth and development cannot be excluded

  16. The role of nitric oxide in the interaction of Arabidopsis thaliana with the biotrophic fungi, Golovinomyces orontii and Erysiphe pisi.

    PubMed

    Schlicht, Markus; Kombrink, Erich

    2013-01-01

    Powdery mildews are a diverse group of pathogenic fungi that can infect a large number of plant species, including many economically important crops. However, basic and applied research on these devastating diseases has been hampered by the obligate biotrophic lifestyle of the pathogens, which require living host cells for growth and reproduction, and lacking genetic and molecular tools for important host plants. The establishment of Arabidopsis thaliana as a host of different powdery mildew species allowed pursuing new strategies to study the molecular mechanisms governing these complex plant-pathogen interactions. Nitric oxide (NO) has emerged as an important signaling molecule in plants, which is produced upon infection and involved in activation of plant immune responses. However, the source and pathway of NO production and its precise function in the regulatory network of reactions leading to resistance is still unknown. We studied the response of Arabidopsis thaliana to infection with the adapted powdery mildew, Golovinomyces orontii (compatible interaction) and the non-adapted, Erysiphe pisi (incompatible interaction). We observed that NO accumulated rapidly and transiently at infection sites and we established a correlation between the resistance phenotype and the amount and timing of NO production. Arabidopsis mutants with defective immune response accumulated lower NO levels compared to wild type. Conversely, increased NO levels, generated by treatment with chemicals or expression of a NO-synthesizing enzyme, resulted in enhanced resistance, but only sustained NO production prevented excessive leaf colonization by the fungus, which was not achieved by a short NO burst although this reduced the initial penetration success. By contrast, lowered NO levels did not impair the ultimate resistance phenotype. Although our results suggest a function of NO in mediating plant immune responses, a direct impact on pathogen growth and development cannot be excluded.

  17. Sequence and analysis of chromosome 4 of the plant Arabidopsis thaliana.

    PubMed

    Mayer, K; Schüller, C; Wambutt, R; Murphy, G; Volckaert, G; Pohl, T; Düsterhöft, A; Stiekema, W; Entian, K D; Terryn, N; Harris, B; Ansorge, W; Brandt, P; Grivell, L; Rieger, M; Weichselgartner, M; de Simone, V; Obermaier, B; Mache, R; Müller, M; Kreis, M; Delseny, M; Puigdomenech, P; Watson, M; Schmidtheini, T; Reichert, B; Portatelle, D; Perez-Alonso, M; Boutry, M; Bancroft, I; Vos, P; Hoheisel, J; Zimmermann, W; Wedler, H; Ridley, P; Langham, S A; McCullagh, B; Bilham, L; Robben, J; Van der Schueren, J; Grymonprez, B; Chuang, Y J; Vandenbussche, F; Braeken, M; Weltjens, I; Voet, M; Bastiaens, I; Aert, R; Defoor, E; Weitzenegger, T; Bothe, G; Ramsperger, U; Hilbert, H; Braun, M; Holzer, E; Brandt, A; Peters, S; van Staveren, M; Dirske, W; Mooijman, P; Klein Lankhorst, R; Rose, M; Hauf, J; Kötter, P; Berneiser, S; Hempel, S; Feldpausch, M; Lamberth, S; Van den Daele, H; De Keyser, A; Buysshaert, C; Gielen, J; Villarroel, R; De Clercq, R; Van Montagu, M; Rogers, J; Cronin, A; Quail, M; Bray-Allen, S; Clark, L; Doggett, J; Hall, S; Kay, M; Lennard, N; McLay, K; Mayes, R; Pettett, A; Rajandream, M A; Lyne, M; Benes, V; Rechmann, S; Borkova, D; Blöcker, H; Scharfe, M; Grimm, M; Löhnert, T H; Dose, S; de Haan, M; Maarse, A; Schäfer, M; Müller-Auer, S; Gabel, C; Fuchs, M; Fartmann, B; Granderath, K; Dauner, D; Herzl, A; Neumann, S; Argiriou, A; Vitale, D; Liguori, R; Piravandi, E; Massenet, O; Quigley, F; Clabauld, G; Mündlein, A; Felber, R; Schnabl, S; Hiller, R; Schmidt, W; Lecharny, A; Aubourg, S; Chefdor, F; Cooke, R; Berger, C; Montfort, A; Casacuberta, E; Gibbons, T; Weber, N; Vandenbol, M; Bargues, M; Terol, J; Torres, A; Perez-Perez, A; Purnelle, B; Bent, E; Johnson, S; Tacon, D; Jesse, T; Heijnen, L; Schwarz, S; Scholler, P; Heber, S; Francs, P; Bielke, C; Frishman, D; Haase, D; Lemcke, K; Mewes, H W; Stocker, S; Zaccaria, P; Bevan, M; Wilson, R K; de la Bastide, M; Habermann, K; Parnell, L; Dedhia, N; Gnoj, L; Schutz, K; Huang, E; Spiegel, L; Sehkon, M; Murray, J; Sheet, P; Cordes, M; Abu-Threideh, J; Stoneking, T; Kalicki, J; Graves, T; Harmon, G; Edwards, J; Latreille, P; Courtney, L; Cloud, J; Abbott, A; Scott, K; Johnson, D; Minx, P; Bentley, D; Fulton, B; Miller, N; Greco, T; Kemp, K; Kramer, J; Fulton, L; Mardis, E; Dante, M; Pepin, K; Hillier, L; Nelson, J; Spieth, J; Ryan, E; Andrews, S; Geisel, C; Layman, D; Du, H; Ali, J; Berghoff, A; Jones, K; Drone, K; Cotton, M; Joshu, C; Antonoiu, B; Zidanic, M; Strong, C; Sun, H; Lamar, B; Yordan, C; Ma, P; Zhong, J; Preston, R; Vil, D; Shekher, M; Matero, A; Shah, R; Swaby, I K; O'Shaughnessy, A; Rodriguez, M; Hoffmann, J; Till, S; Granat, S; Shohdy, N; Hasegawa, A; Hameed, A; Lodhi, M; Johnson, A; Chen, E; Marra, M; Martienssen, R; McCombie, W R

    1999-12-16

    The higher plant Arabidopsis thaliana (Arabidopsis) is an important model for identifying plant genes and determining their function. To assist biological investigations and to define chromosome structure, a coordinated effort to sequence the Arabidopsis genome was initiated in late 1996. Here we report one of the first milestones of this project, the sequence of chromosome 4. Analysis of 17.38 megabases of unique sequence, representing about 17% of the genome, reveals 3,744 protein coding genes, 81 transfer RNAs and numerous repeat elements. Heterochromatic regions surrounding the putative centromere, which has not yet been completely sequenced, are characterized by an increased frequency of a variety of repeats, new repeats, reduced recombination, lowered gene density and lowered gene expression. Roughly 60% of the predicted protein-coding genes have been functionally characterized on the basis of their homology to known genes. Many genes encode predicted proteins that are homologous to human and Caenorhabditis elegans proteins.

  18. Arabidopsis thaliana is a susceptible host plant for the holoparasite Cuscuta spec.

    PubMed

    Birschwilks, Mandy; Sauer, Norbert; Scheel, Dierk; Neumann, Stefanie

    2007-10-01

    Arabidopsis thaliana and Cuscuta spec. represent a compatible host-parasite combination. Cuscuta produces a haustorium that penetrates the host tissue. In early stages of development the searching hyphae on the tip of the haustorial cone are connected to the host tissue by interspecific plasmodesmata. Ten days after infection, translocation of the fluorescent dyes, Texas Red (TR) and 5,6-carboxyfluorescein (CF), demonstrates the existence of a continuous connection between xylem and phloem of the host and parasite. Cuscuta becomes the dominant sink in this host-parasite system. Transgenic Arabidopsis plants expressing genes encoding the green fluorescent protein (GFP; 27 kDa) or a GFP-ubiquitin fusion (36 kDa), respectively, under the companion cell (CC)-specific AtSUC2 promoter were used to monitor the transfer of these proteins from the host sieve elements to those of Cuscuta. Although GFP is transferred unimpedly to the parasite, the GFP-ubiquitin fusion could not be detected in Cuscuta. A translocation of the GFP-ubiquitin fusion protein was found to be restricted to the phloem of the host, although a functional symplastic pathway exists between the host and parasite, as demonstrated by the transport of CF. These results indicate a peripheral size exclusion limit (SEL) between 27 and 36 kDa for the symplastic connections between host and Cuscuta sieve elements. Forty-six accessions of A. thaliana covering the entire range of its genetic diversity, as well as Arabidopsis halleri, were found to be susceptible towards Cuscuta reflexa.

  19. Evidence for the Existence in Arabidopsis thaliana of the Proteasome Proteolytic Pathway

    PubMed Central

    Polge, Cécile; Jaquinod, Michel; Holzer, Frances; Bourguignon, Jacques; Walling, Linda; Brouquisse, Renaud

    2009-01-01

    Heavy metals are known to generate reactive oxygen species that lead to the oxidation and fragmentation of proteins, which become toxic when accumulated in the cell. In this study, we investigated the role of the proteasome during cadmium stress in the leaves of Arabidopsis thaliana plants. Using biochemical and proteomics approaches, we present the first evidence of an active proteasome pathway in plants. We identified and characterized the peptidases acting sequentially downstream from the proteasome in animal cells as follows: tripeptidyl-peptidase II, thimet oligopeptidase, and leucine aminopeptidase. We investigated the proteasome proteolytic pathway response in the leaves of 6-week-old A. thaliana plants grown hydroponically for 24, 48, and 144 h in the presence or absence of 50 μm cadmium. The gene expression and proteolytic activity of the proteasome and the different proteases of the pathway were found to be up-regulated in response to cadmium. In an in vitro assay, oxidized bovine serum albumin and lysozyme were more readily degraded in the presence of 20 S proteasome and tripeptidyl-peptidase II than their nonoxidized form, suggesting that oxidized proteins are preferentially degraded by the Arabidopsis 20 S proteasome pathway. These results show that, in response to cadmium, the 20 S proteasome proteolytic pathway is up-regulated at both RNA and activity levels in Arabidopsis leaves and may play a role in degrading oxidized proteins generated by the stress. PMID:19822524

  20. Characterization and Prediction of Protein Phosphorylation Hotspots in Arabidopsis thaliana.

    PubMed

    Christian, Jan-Ole; Braginets, Rostyslav; Schulze, Waltraud X; Walther, Dirk

    2012-01-01

    The regulation of protein function by modulating the surface charge status via sequence-locally enriched phosphorylation sites (P-sites) in so called phosphorylation "hotspots" has gained increased attention in recent years. We set out to identify P-hotspots in the model plant Arabidopsis thaliana. We analyzed the spacing of experimentally detected P-sites within peptide-covered regions along Arabidopsis protein sequences as available from the PhosPhAt database. Confirming earlier reports (Schweiger and Linial, 2010), we found that, indeed, P-sites tend to cluster and that distributions between serine and threonine P-sites to their respected closest next P-site differ significantly from those for tyrosine P-sites. The ability to predict P-hotspots by applying available computational P-site prediction programs that focus on identifying single P-sites was observed to be severely compromised by the inevitable interference of nearby P-sites. We devised a new approach, named HotSPotter, for the prediction of phosphorylation hotspots. HotSPotter is based primarily on local amino acid compositional preferences rather than sequence position-specific motifs and uses support vector machines as the underlying classification engine. HotSPotter correctly identified experimentally determined phosphorylation hotspots in A. thaliana with high accuracy. Applied to the Arabidopsis proteome, HotSPotter-predicted 13,677 candidate P-hotspots in 9,599 proteins corresponding to 7,847 unique genes. Hotspot containing proteins are involved predominantly in signaling processes confirming the surmised modulating role of hotspots in signaling and interaction events. Our study provides new bioinformatics means to identify phosphorylation hotspots and lays the basis for further investigating novel candidate P-hotspots. All phosphorylation hotspot annotations and predictions have been made available as part of the PhosPhAt database at http://phosphat.mpimp-golm.mpg.de.

  1. Arabidopsis thaliana as Bioindicator of Fungal VOCs in Indoor Air

    PubMed Central

    Hung, Richard; Yin, Guohua; Klich, Maren A.; Grimm, Casey; Bennett, Joan W.

    2016-01-01

    In this paper, we demonstrate the ability of Arabidopsis thaliana to detect different mixtures of volatile organic compounds (VOCs) emitted by the common indoor fungus, Aspergillus versicolor, and demonstrate the potential usage of the plant as a bioindicator to monitor fungal VOCs in indoor air. We evaluated the volatile production of Aspergillus versicolor strains SRRC 108 (NRRL 3449) and SRRC 2559 (ATCC 32662) grown on nutrient rich fungal medium, and grown under conditions to mimic the substrate encountered in the built environment where fungi would typically grow indoors (moist wallboard and ceiling tiles). Using headspace solid phase microextraction/gas chromatography-mass spectrometry, we analyzed VOC profiles of the two strains. The most abundant compound produced by both strains on all three media was 1-octen-3-ol. Strain SRRC 2559 made several terpenes not detected from strain SRRC 108. Using a split-plate bioassay, we grew Arabidopsis thaliana in a shared atmosphere with VOCs from the two strains of Aspergillus versicolor grown on yeast extract sucrose medium. The VOCs emitted by SRRC 2559 had an adverse impact on seed germination and plant growth. Chemical standards of individual VOCs from the Aspergillus versicolor mixture (2-methyl-1-butanol, 3-methyl-1-butanol, 1-octen-3-ol, limonene, and β-farnesene), and β-caryophyllene were tested one by one in seed germination and vegetative plant growth assays. The most inhibitory compound to both seed germination and plant growth was 1-octen-3-ol. Our data suggest that Arabidopsis is a useful model for monitoring indoor air quality as it is sensitive to naturally emitted fungal volatile mixtures as well as to chemical standards of individual compounds, and it exhibits relatively quick concentration- and duration-dependent responses. PMID:27790067

  2. Arabidopsis thaliana as Bioindicator of Fungal VOCs in Indoor Air.

    PubMed

    Lee, Samantha; Hung, Richard; Yin, Guohua; Klich, Maren A; Grimm, Casey; Bennett, Joan W

    2016-09-01

    In this paper, we demonstrate the ability of Arabidopsis thaliana to detect different mixtures of volatile organic compounds (VOCs) emitted by the common indoor fungus, Aspergillus versicolor , and demonstrate the potential usage of the plant as a bioindicator to monitor fungal VOCs in indoor air. We evaluated the volatile production of Aspergillus versicolor strains SRRC 108 (NRRL 3449) and SRRC 2559 (ATCC 32662) grown on nutrient rich fungal medium, and grown under conditions to mimic the substrate encountered in the built environment where fungi would typically grow indoors (moist wallboard and ceiling tiles). Using headspace solid phase microextraction/gas chromatography-mass spectrometry, we analyzed VOC profiles of the two strains. The most abundant compound produced by both strains on all three media was 1-octen-3-ol. Strain SRRC 2559 made several terpenes not detected from strain SRRC 108. Using a split-plate bioassay, we grew Arabidopsis thaliana in a shared atmosphere with VOCs from the two strains of Aspergillus versicolor grown on yeast extract sucrose medium. The VOCs emitted by SRRC 2559 had an adverse impact on seed germination and plant growth. Chemical standards of individual VOCs from the Aspergillus versicolor mixture (2-methyl-1-butanol, 3-methyl-1-butanol, 1-octen-3-ol, limonene, and β-farnesene), and β-caryophyllene were tested one by one in seed germination and vegetative plant growth assays. The most inhibitory compound to both seed germination and plant growth was 1-octen-3-ol. Our data suggest that Arabidopsis is a useful model for monitoring indoor air quality as it is sensitive to naturally emitted fungal volatile mixtures as well as to chemical standards of individual compounds, and it exhibits relatively quick concentration- and duration-dependent responses.

  3. Phytochelatin Synthesis Promotes Leaf Zn Accumulation of Arabidopsis thaliana Plants Grown in Soil with Adequate Zn Supply and is Essential for Survival on Zn-Contaminated Soil.

    PubMed

    Kühnlenz, Tanja; Hofmann, Christian; Uraguchi, Shimpei; Schmidt, Holger; Schempp, Stefanie; Weber, Michael; Lahner, Brett; Salt, David E; Clemens, Stephan

    2016-11-01

    Phytochelatin (PC) synthesis is essential for the detoxification of non-essential metals such as cadmium (Cd). In vitro experiments with Arabidopsis thaliana seedlings had indicated a contribution to zinc (Zn) tolerance as well. We addressed the physiological role of PC synthesis in Zn homeostasis of plants under more natural conditions. Growth responses, PC accumulation and leaf ionomes of wild-type and AtPCS1 mutant plants cultivated in different soils representing adequate Zn supply, Zn deficiency and Zn excess were analyzed. Growth on Zn-contaminated soil triggers PC synthesis and is strongly impaired in PC-deficient mutants. In fact, the contribution of AtPCS1 to tolerating Zn excess is comparable with that of the major Zn tolerance factor MTP1. For plants supplied with a normal level of Zn, a significant reduction in leaf Zn accumulation of AtPCS1 mutants was detected. In contrast, AtPCS1 mutants grown under Zn-limited conditions showed wild-type levels of Zn accumulation, suggesting the operation of distinct Zn translocation pathways. Contrasting phenotypes of the tested AtPCS1 mutant alleles upon growth in Zn- or Cd-contaminated soil indicated differential activation of PC synthesis by these metals. Experiments with truncated versions identified a part of the AtPCS1 protein required for the activation by Zn but not by Cd. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  4. Structure and Function of Centromeric and Pericentromeric Heterochromatin in Arabidopsis thaliana.

    PubMed

    Simon, Lauriane; Voisin, Maxime; Tatout, Christophe; Probst, Aline V

    2015-01-01

    The centromere is a specific chromosomal region where the kinetochore assembles to ensure the faithful segregation of sister chromatids during mitosis and meiosis. Centromeres are defined by a local enrichment of the specific histone variant CenH3 mostly at repetitive satellite sequences. A larger pericentromeric region containing repetitive sequences and transposable elements surrounds the centromere that adopts a particular chromatin state characterized by specific histone variants and post-translational modifications and forms a transcriptionally repressive chromosomal environment. In the model organism Arabidopsis thaliana centromeric and pericentromeric domains form conspicuous heterochromatin clusters called chromocenters in interphase. Here we discuss, using Arabidopsis as example, recent insight into mechanisms involved in maintenance and establishment of centromeric and pericentromeric chromatin signatures as well as in chromocenter formation.

  5. The NADPH-oxidase AtRbohI plays a positive role in drought-stress response in Arabidopsis thaliana

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

    He, Huan; Yan, Jingwei; Yu, Xiaoyun

    As the major resource of reactive oxygen species (ROS), the NADPH oxidases (Rbohs) have been shown to play important roles in plant cells under normal growth and stress conditions. Although many family members of Rbohs were studied, little is known about the function of RbohI in Arabidopsis thaliana. Here, we report that exogenous ABA application decreases RbohI expression and mannitol significantly increases RbohI expression at transcript level. The RbohI transcripts were strongly detected in dry seeds and roots. The loss-of-function mutant rbohI exhibited sensitivity to ABA and mannitol stress during germination. Furthermore, the lateral root growth of rbohI was severelymore » inhibited after treatment with mannitol stress. Overexpression of RbohI in Arabidopsis significantly improves the drought tolerance. Moreover, more H 2O 2 accumulated in RbohI overexpressors than in wild type plants in response to mannitol stress. Our conclusion is that AtRbohI functions in drought-stress response in Arabidopsis thaliana.« less

  6. Interaction of light and gravitropism with nutation of hypocotyls of Arabidopsis thaliana seedlings

    NASA Technical Reports Server (NTRS)

    Orbovic, V.; Poff, K. L.

    1997-01-01

    Etiolated seedlings of Arabidopsis thaliana nutated under conditions of physiological darkness while about ten percent of monitored individuals exhibited regular elliptical nutation, circumnutation. Pre-irradiation with red light prevented occurrence of circumnutation without having an effect on the average rate of the nutational movement. Phototropic response of seedlings to unilateral blue light appeared to be superimposed over nutation. Throughout gravitropism, some seedlings continued to exhibit nutation suggesting that these two processes are independently controlled. Based on these results, we suggest that nutation in Arabidopsis probably is not controlled by the mechanism predicted by the theory of gravitropic overshoots.

  7. Analysis of multiple photoreceptor pigments for phototropism in a mutant of Arabidopsis thaliana

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    The shape of the fluence-response relationship for the phototropic response of the JK224 strain of Arabidopsis thaliana depends on the fluence rate and wavelength of the actinic light. At low fluence rate (0.1 micromole m-2 s-1), the response to 450-nm light is characterized by a single maximum at about 9 micromoles m-2. At higher fluence rate (0.4 micromole m-2 s-1), the response shows two maxima, at 4.5 and 9 micromoles m-2. The response to 510-nm light shows a single maximum at 4.5 micromoles m-2. Unilateral preirradiation with high fluence rate (25 micromoles m-2 s-1) 510-nm light eliminates the maximum at 4.5 micromoles m-2 in the fluence response curve to a subsequent unilateral 450-nm irradiation, while the second maximum at 9 micromoles m-2 is unaffected. Based on these results, it is concluded that a single photoreceptor pigment has been altered in the JK224 strain of Arabidopsis thaliana.

  8. Proteomic alterations in root tips of Arabidopsis thaliana seedlings under altered gravity conditions

    NASA Astrophysics Data System (ADS)

    Zheng, H. Q.; Wang, H.

    Gravity has a profound influence on plant growth and development Removed the influence of gravitational acceleration by spaceflight caused a wide range of cellular changes in plant Whole seedling that germinated and grown on clinostats showed the absent of gravitropism At the cellular level clinostat treatment has specific effects on plant cells such as induce alterations in cell wall composition increase production of heat-soluble proteins impact on the cellular energy metabolism facilitate a uniform distribution of plastids amyloplasts and increase number and volume of nucleoli A number of recent studies have shown that the exposure of Arabidopsis seedlings and callus cells to gravity stimulation hyper g-forces or clinostat rotation induces alterations in gene expression In our previous study the proteome of the Arabidopsis thaliana callus cells were separated by high resolution two-dimensional electrophoresis 2-DE Image analysis revealed that 80 protein spots showed quantitative and qualitative variations after exposure to clinostat rotation treatment We report here a systematic proteomic approach to investigate the altered gravity responsive proteins in root tip of Arabidopsis thaliana cv Landsberg erecta Three-day-old seedlings were exposed for 12h to a horizontal clinostat rotation H simulated weightlessness altered g-forces by centrifugation 7g hypergravity a vertical clinostat rotation V clinostat control or a stationary control grown conditions Total proteins of roots were extracted

  9. Carbon and hydrogen isotopic effects of stomatal density in Arabidopsis thaliana

    NASA Astrophysics Data System (ADS)

    Lee, Hyejung; Feakins, Sarah J.; Sternberg, Leonel da S. L.

    2016-04-01

    Stomata are key gateways mediating carbon uptake and water loss from plants. Varied stomatal densities in fossil leaves raise the possibility that isotope effects associated with the openness of exchange may have mediated plant wax biomarker isotopic proxies for paleovegetation and paleoclimate in the geological record. Here we use Arabidopsis thaliana, a widely used model organism, to provide the first controlled tests of stomatal density on carbon and hydrogen isotopic compositions of cuticular waxes. Laboratory grown wildtype and mutants with suppressed and overexpressed stomatal densities allow us to directly test the isotope effects of stomatal densities independent of most other environmental or biological variables. Hydrogen isotope (D/H) measurements of both plant waters and plant wax n-alkanes allow us to directly constrain the isotopic effects of leaf water isotopic enrichment via transpiration and biosynthetic fractionations, which together determine the net fractionation between irrigation water and n-alkane hydrogen isotopic composition. We also measure carbon isotopic fractionations of n-alkanes and bulk leaf tissue associated with different stomatal densities. We find offsets of +15‰ for δD and -3‰ for δ13C for the overexpressed mutant compared to the suppressed mutant. Since the range of stomatal densities expressed is comparable to that found in extant plants and the Cenozoic fossil record, the results allow us to consider the magnitude of isotope effects that may be incurred by these plant adaptive responses. This study highlights the potential of genetic mutants to isolate individual isotope effects and add to our fundamental understanding of how genetics and physiology influence plant biochemicals including plant wax biomarkers.

  10. Three-dimensional patterns of cell division and expansion throughout the development of Arabidopsis thaliana leaves.

    PubMed

    Kalve, Shweta; Fotschki, Joanna; Beeckman, Tom; Vissenberg, Kris; Beemster, Gerrit T S

    2014-12-01

    Variations in size and shape of multicellular organs depend on spatio-temporal regulation of cell division and expansion. Here, cell division and expansion rates were quantified relative to the three spatial axes in the first leaf pair of Arabidopsis thaliana. The results show striking differences in expansion rates: the expansion rate in the petiole is higher than in the leaf blade; expansion rates in the lateral direction are higher than longitudinal rates between 5 and 10 days after stratification, but become equal at later stages of leaf blade development; and anticlinal expansion co-occurs with, but is an order of magnitude slower than periclinal expansion. Anticlinal expansion rates also differed greatly between tissues: the highest rates occurred in the spongy mesophyll and the lowest in the epidermis. Cell division rates were higher and continued for longer in the epidermis compared with the palisade mesophyll, causing a larger increase of palisade than epidermal cell area over the course of leaf development. The cellular dynamics underlying the effect of shading on petiole length and leaf thickness were then investigated. Low light reduced leaf expansion rates, which was partly compensated by increased duration of the growth phase. Inversely, shading enhanced expansion rates in the petiole, so that the blade to petiole ratio was reduced by 50%. Low light reduced leaf thickness by inhibiting anticlinal cell expansion rates. This effect on cell expansion was preceded by an effect on cell division, leading to one less layer of palisade cells. The two effects could be uncoupled by shifting plants to contrasting light conditions immediately after germination. This extended kinematic analysis maps the spatial and temporal heterogeneity of cell division and expansion, providing a framework for further research to understand the molecular regulatory mechanisms involved. © The Author 2014. Published by Oxford University Press on behalf of the Society for

  11. 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.

  12. Long-term sulphur starvation of Arabidopsis thaliana modifies mitochondrial ultrastructure and activity and changes tissue energy and redox status.

    PubMed

    Ostaszewska, Monika; Juszczuk, Izabela M; Kołodziejek, Izabella; Rychter, Anna M

    2014-04-15

    Sulphur, as a constituent of amino acids (cysteine and methionine), iron-sulphur clusters, proteins, membrane sulpholipids, glutathione, glucosinolates, coenzymes, and auxin precursors, is essential for plant growth and development. Absence or low sulphur concentration in the soil results in severe growth retardation. Arabidopsis thaliana plants grown hydroponically for nine weeks on Knop nutrient medium without sulphur showed morphological symptoms of sulphur deficiency. The purpose of our study was to investigate changes that mitochondria undergo and the role of the highly branched respiratory chain in survival during sulphur deficiency stress. Ultrastructure analysis of leaf mesophyll cells of sulphur-deficient Arabidopsis showed heterogeneity of mitochondria; some of them were not altered, but the majority had swollen morphology. Dilated mitochondria displayed a lower matrix density and fewer cristae compared to control mitochondria. Disintegration of the inner and outer membranes of some mitochondria from the leaves of sulphur-deficient plants was observed. On the contrary, chloroplast ultrastructure was not affected. Sulphur deficiency changed the respiratory activity of tissues and isolated mitochondria; Complex I and IV capacities and phosphorylation rates were lower, but external NAD(P)H dehydrogenase activity increased. Higher external NAD(P)H dehydrogenase activity corresponded to increased cell redox level with doubled NADH/NAD ratio in the leaf and root tissues. Sulphur deficiency modified energy status in the tissues of Arabidopsis plants. The total concentration of adenylates (expressed as ATP+ADP), measured in the light, was lower in the leaves and roots of sulphur-deficient plants than in the controls, which was mainly due to the severely decreased ATP levels. We show that the changes in mitochondrial ultrastructure are compensated by the modifications in respiratory chain activity. Although mitochondria of Arabidopsis tissues are affected by

  13. 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.

  14. Arabidopsis thaliana type I and II chaperonins

    PubMed Central

    Hill, Janet E.; Hemmingsen, Sean M.

    2001-01-01

    An examination of the Arabidopsis thaliana genome sequence led to the identification of 29 predicted genes with the potential to encode members of the chaperonin family of chaperones (CPN60 and CCT), their associated cochaperonins, and the cytoplasmic chaperonin cofactor prefoldin. These comprise the first complete set of plant chaperonin protein sequences and indicate that the CPN family is more diverse than previously described. In addition to surprising sequence diversity within CPN subclasses, the genomic data also suggest the existence of previously undescribed family members, including a 10-kDa chloroplast cochaperonin. Consideration of the sequence data described in this review prompts questions about the complexities of plant CPN systems and the evolutionary relationships and functions of the component proteins, most of which have not been studied experimentally. PMID:11599560

  15. Arabidopsis thaliana type I and II chaperonins.

    PubMed

    Hill, J E; Hemmingsen, S M

    2001-07-01

    An examination of the Arabidopsis thaliana genome sequence led to the identification of 29 predicted genes with the potential to encode members of the chaperonin family of chaperones (CPN60 and CCT), their associated cochaperonins, and the cytoplasmic chaperonin cofactor prefoldin. These comprise the first complete set of plant chaperonin protein sequences and indicate that the CPN family is more diverse than previously described. In addition to surprising sequence diversity within CPN subclasses, the genomic data also suggest the existence of previously undescribed family members, including a 10-kDa chloroplast cochaperonin. Consideration of the sequence data described in this review prompts questions about the complexities of plant CPN systems and the evolutionary relationships and functions of the component proteins, most of which have not been studied experimentally.

  16. Interactions of light and ethylene in hypocotyl hook maintenance in Arabidopsis thaliana seedlings

    NASA Technical Reports Server (NTRS)

    Knee, E. M.; Hangarter, R. P.; Knee, M.

    2000-01-01

    Etiolated seedlings frequently display a hypocotyl or epicotyl hook which opens on exposure to light. Etylene has been shown to be necessary for maintenance of the hook in a number of plants in darkness. We investigated the interaction of ethylene and light in the regulation of hypocotyl hook opening in Arabidopsis thaliana. We found that hooks of Arabidopsis open in response to continuous red, far-red or blue light in the presence of up to 100 microliters l-1 ethylene. Thus a change in sensitivity to ethylene is likely to be responsible for hook opening in Arabidopsis, rather than a decrease in ethylene production in hook tissues. We used photomorphogenic mutants of Arabidopsis to demonstrate the involvement of both blue light and phytochrome photosensory systems in light-induced hook opening in the presence of ethylene. In addition we used ethylene mutants and inhibitors of ethylene action to investigate the role of ethylene in hook maintenance in seedlings grown in light and darkness.

  17. Arabidopsis thaliana as a tool to identify traits involved in Verticillium dahliae biocontrol by the olive root endophyte Pseudomonas fluorescens PICF7

    PubMed Central

    Maldonado-González, M. Mercedes; Bakker, Peter A. H. M.; Prieto, Pilar; Mercado-Blanco, Jesús

    2015-01-01

    The effective management of Verticillium wilts (VW), diseases affecting many crops and caused by some species of the soil-borne fungus Verticillium, is problematic. The use of microbial antagonists to control these pathologies fits modern sustainable agriculture criteria. Pseudomonas fluorescens PICF7 is an endophytic bacterium isolated from olive roots with demonstrated ability to control VW of olive caused by the highly virulent, defoliating (D) pathotype of Verticillium dahliae Kleb. However, the study of the PICF7-V. dahliae-olive tripartite interaction poses difficulties because of the inherent characteristics of woody, long-living plants. To overcome these problems we explored the use of the model plant Arabidopsis thaliana. Results obtained in this study showed that: (i) olive D and non-defoliating V. dahliae pathotypes produce differential disease severity in A. thaliana plants; (ii) strain PICF7 is able to colonize and persist in the A. thaliana rhizosphere but is not endophytic in Arabidopsis; and (iii) strain PICF7 controls VW in Arabidopsis. Additionally, as previously observed in olive, neither swimming motility nor siderophore production by PICF7 are required for VW control in A. thaliana, whilst cysteine auxotrophy decreased the effectiveness of PICF7. Moreover, when applied to the roots PICF7 controlled Botrytis cinerea infection in the leaves of Arabidopsis, suggesting that this strain is able to induce systemic resistance. A. thaliana is therefore a suitable alternative to olive bioassays to unravel biocontrol traits involved in biological control of V. dahliae by P. fluorescens PICF7. PMID:25904904

  18. Exploring ammonium tolerance in a large panel of Arabidopsis thaliana natural accessions

    PubMed Central

    Sarasketa, Asier; González-Moro, María Begoña; González-Murua, Carmen; Marino, Daniel

    2014-01-01

    Plants are dependent on exogenous nitrogen (N) supply. Ammonium (NH4 +), together with nitrate (NO3 –), is one of the main nitrogenous compounds available in the soil. Paradoxically, although NH4 + assimilation requires less energy than that of NO3 –, many plants display toxicity symptoms when grown with NH4 + as the sole N source. However, in addition to species-specific ammonium toxicity, intraspecific variability has also been shown. Thus, the aim of this work was to study the intraspecific ammonium tolerance in a large panel of Arabidopsis thaliana natural accessions. Plants were grown with either 1mM NO3 – or NH4 + as the N source, and several parameters related to ammonium tolerance and assimilation were determined. Overall, high variability was observed in A. thaliana shoot growth under both forms of N nutrition. From the parameters determined, tissue ammonium content was the one with the highest impact on shoot biomass, and interestingly this was also the case when N was supplied as NO3 –. Enzymes of nitrogen assimilation did not have an impact on A. thaliana biomass variation, but the N source affected their activity. Glutamate dehydrogenase (GDH) aminating activity was, in general, higher in NH4 +-fed plants. In contrast, GDH deaminating activity was higher in NO3 –-fed plants, suggesting a differential role for this enzyme as a function of the N form supplied. Overall, NH4 + accumulation seems to be an important player in Arabidopsis natural variability in ammonium tolerance rather than the cell NH4 + assimilation capacity. PMID:25205573

  19. Transgenic expression of plant-specific insert of potato aspartic proteases (StAP-PSI) confers enhanced resistance to Botrytis cinerea in Arabidopsis thaliana.

    PubMed

    Frey, María Eugenia; D'Ippolito, Sebastián; Pepe, Alfonso; Daleo, Gustavo Raúl; Guevara, María Gabriela

    2018-05-01

    The plant-specific insert of Solanum tuberosum aspartic proteases (StAP-PSI) has high structural similarity with NK-lysin and granulysin, two saposin-like proteins (SAPLIPs) with antimicrobial activity. Recombinant StAP-PSI and some SAPLIPs show antimicrobial activity against pathogens that affect human and plants. In this work, we transformed Arabidopsis thaliana plants with StAP-PSI encoding sequence with its corresponding signal peptide under the control of the cauliflower mosaic virus (CaMV) 35S promoter. Results obtained show that StAP-PSI significantly enhances Arabidopsis resistance against Botrytis cinerea infection. StAP-PSI is secreted into the leaf apoplast and acts directly against pathogens; thereby complementing plant innate immune responses. Data obtained from real-time PCR assays show that the constitutive expression of StAP-PSI induces the expression of genes that regulate jasmonic acid signalling pathway, such as PDF1.2, in response to infection due to necrotrophic pathogens. On the other hand, according to the data described for other antimicrobial peptides, the presence of the StAP-PSI protein in the apoplast of A. thaliana leaves is responsible for the expression of salicylic acid-associated genes, such as PR-1, irrespective of infection with B. cinerea. These results indicate that the increased resistance demonstrated by A. thaliana plants that constitutively express StAP-PSI owing to B. cinerea infection compared to the wild-type plants is a consequence of two factors, i.e., the antifungal activity of StAP-PSI and the overexpression of A. thaliana defense genes induced by the constitutive expression of StAP-PSI. We suggest that the use of this protein would help in minimizing the ecological and health risks that arise from the use of pesticides. We suggest that the use of this protein would help in minimizing the ecological and health risks that arise from the spreading of resistance of agriculturally important pathogens. Copyright

  20. 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

  1. DNA Gyrase Is the Target for the Quinolone Drug Ciprofloxacin in Arabidopsis thaliana*

    PubMed Central

    Evans-Roberts, Katherine M.; Mitchenall, Lesley A.; Wall, Melisa K.; Leroux, Julie; Mylne, Joshua S.; Maxwell, Anthony

    2016-01-01

    The Arabidopsis thaliana genome contains four genes that were originally annotated as potentially encoding DNA gyrase: ATGYRA, ATGYRB1, ATGYRB2, and ATGYRB3. Although we subsequently showed that ATGYRB3 does not encode a gyrase subunit, the other three genes potentially encode subunits of a plant gyrase. We also showed evidence for the existence of supercoiling activity in A. thaliana and that the plant is sensitive to quinolone and aminocoumarin antibiotics, compounds that target DNA gyrase in bacteria. However, it was not possible at that time to show whether the A. thaliana genes encoded an active gyrase enzyme, nor whether that enzyme is indeed the target for the quinolone and aminocoumarin antibiotics. Here we show that an A. thaliana mutant resistant to the quinolone drug ciprofloxacin has a point mutation in ATGYRA. Moreover we show that, as in bacteria, the quinolone-sensitive (wild-type) allele is dominant to the resistant gene. Further we have heterologously expressed ATGYRA and ATGYRB2 in a baculovirus expression system and shown supercoiling activity of the partially purified enzyme. Expression/purification of the quinolone-resistant A. thaliana gyrase yields active enzyme that is resistant to ciprofloxacin. Taken together these experiments now show unequivocally that A. thaliana encodes an organelle-targeted DNA gyrase that is the target of the quinolone drug ciprofloxacin; this has important consequences for plant physiology and the development of herbicides. PMID:26663076

  2. In Planta Response of Arabidopsis to Photothermal Impact Mediated by Gold Nanoparticles.

    PubMed

    Koo, Yeonjong; Lukianova-Hleb, Ekaterina Y; Pan, Joann; Thompson, Sean M; Lapotko, Dmitri O; Braam, Janet

    2016-02-03

    Biological responses to photothermal effects of gold nanoparticles (GNPs) have been demonstrated and employed for various applications in diverse systems except for one important class - plants. Here, the uptake of GNPs through Arabidopsis thaliana roots and translocation to leaves are reported. Successful plasmonic nanobubble generation and acoustic signal detection in planta is demonstrated. Furthermore, Arabidopsis leaves harboring GNPs and exposed to continuous laser or noncoherent light show elevated temperatures across the leaf surface and induced expression of heat-shock regulated genes. Overall, these results demonstrate that Arabidopsis can readily take up GNPs through the roots and translocate the particles to leaf tissues. Once within leaves, GNPs can act as photothermal agents for on-demand remote activation of localized biological processes in plants. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. [Distribution and speciation of Pb in Arabidopsis thaliana shoot and rhizosphere soil by in situ synchrotron radiation micro X-ray fluorescence and X-ray absorption near edge structure].

    PubMed

    Shen, Ya-Ting

    2014-03-01

    In order to investigate plant reacting mechanism with heavy metal stress in organ and tissue level, synchrotron radiation micro X-ray fluorescence (micro-SRXRF) was used to determine element distribution characteristics of K, Ca, Mn, Fe, Cu, Zn, Pb in an Arabidopsis thaliana seedling grown in tailing dam soil taken from a lead-zinc mine exploration area. The results showed a regular distribution characters of K, Ca, Fe, Cu and Zn, while Pb appeared not only in root, but also in a leaf bud which was beyond previously understanding that Pb mainly appeared in plant root. Pb competed with Mn in the distribution of the whole seedling. Pb may cause the increase of oxidative stress in root and leaf bud, and restrict Mn absorption and utilization which explained the phenomenon of seedling death in this tailing damp soil. Speciation of Pb in Arabidopsis thaliana and tailing damp rhizosphere soil were also presented after using PbL3 micro X-ray absorption near edge structure (micro-XANES). By comparison of PbL3 XANES peak shape and peak position between standard samples and rhizosphere soil sample, it was demonstrated that the tailing damp soil was mainly formed by amorphous forms like PbO (64.2%), Pb (OH)2 (28.8%) and Pb3O4 (6.3%) rather than mineral or organic Pb speciations. The low plant bioavailability of Pb demonstrated a further research focusing on Pb absorption and speciation conversion is needed, especially the role of dissolve organic matter in soil which may enhance Pb bioavailability.

  4. A composite transcriptional signature differentiates responses towards closely related herbicides in Arabidopsis thaliana and brassica napus

    EPA Science Inventory

    In this study, genome-wide expression profiling based on Affymetrix ATH1 arrays was used to identify discriminating responses of Arabidopsis thaliana to five herbicides, which contain active ingredients targeting two different branches of amino acid biosynthesis. One herbicide co...

  5. Multi-Element Bioimaging of Arabidopsis thaliana Roots1[OPEN

    PubMed Central

    Salt, David E.

    2016-01-01

    Better understanding of root function is central for the development of plants with more efficient nutrient uptake and translocation. We here present a method for multielement bioimaging at the cellular level in roots of the genetic model system Arabidopsis (Arabidopsis thaliana). Using conventional protocols for microscopy, we observed that diffusible ions such as potassium and sodium were lost during sample dehydration. Thus, we developed a protocol that preserves ions in their native, cellular environment. Briefly, fresh roots are encapsulated in paraffin, cryo-sectioned, and freeze dried. Samples are finally analyzed by laser ablation-inductively coupled plasma-mass spectrometry, utilizing a specially designed internal standard procedure. The method can be further developed to maintain the native composition of proteins, enzymes, RNA, and DNA, making it attractive in combination with other omics techniques. To demonstrate the potential of the method, we analyzed a mutant of Arabidopsis unable to synthesize the metal chelator nicotianamine. The mutant accumulated substantially more zinc and manganese than the wild type in the tissues surrounding the vascular cylinder. For iron, the images looked completely different, with iron bound mainly in the epidermis of the wild-type plants but confined to the cortical cell walls of the mutant. The method offers the power of inductively coupled plasma-mass spectrometry to be fully employed, thereby providing a basis for detailed studies of ion transport in roots. Being applicable to Arabidopsis, the molecular and genetic approaches available in this system can now be fully exploited in order to gain a better mechanistic understanding of these processes. PMID:27566167

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

    DOE PAGES

    Liu, Fushan; Zhao, Qianru; Mano, Noel; ...

    2015-08-19

    Here, 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 oilseedmore » 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.« less

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

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

    Liu, Fushan; Zhao, Qianru; Mano, Noel

    Here, 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 oilseedmore » 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.« less

  8. 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. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  9. Systemic resistance induced in Arabidopsis thaliana by Trichoderma asperellum SKT-1, a microbial pesticide of seedborne diseases of rice.

    PubMed

    Yoshioka, Yohei; Ichikawa, Haruki; Naznin, Hushna Ara; Kogure, Atsushi; Hyakumachi, Mitsuro

    2012-01-01

    Trichoderma asperellum SKT-1 is a microbial pesticide of seedborne diseases of rice. To investigate the mechanisms of disease suppression in SKT-1, the ability to induce systemic resistance by SKT-1, or its cell-free culture filtrate (CF), was tested using Arabidopsis thaliana Col-0 plants. Both SKT-1 and its CF elicit an induced systemic resistance against the bacterial leaf speck pathogen Pseudomonas syringae pv. tomato DC3000 in Col-0 plants. Involvement of plant hormones in the induced resistance by SKT-1 and CF was assessed using Arabidopsis genotypes such as the jasmonic acid (JA)-resistant mutant jar1, the ethylene (ET)-resistant mutant etr1, the plant impaired in salicylic acid (SA) signalling transgenic NahG and the mutant npr1 impaired in NPR1 activity. In soil experiments using SKT-1, no significant disease suppression effect was observed in NahG transgenic plants or npr1 mutant plants. Expression levels of SA-inducible genes such as PR-1, PR-2 and PR-5 increased substantially in the leaves of Col-0 plants. Expression levels of JA/ET-induced genes such as PDF1.2a, PR-3, PR-4 and AtVsp1 were also induced, but the levels were not as high as for SA-inducible genes. In a hydroponic experiment using CF from SKT-1, all Arabidopsis genotypes showed an induced systemic resistance by CF and increased expression levels of JA/ET- and SA-inducible genes in leaves of CF-treated plants. The SA signalling pathway is important in inducing systemic resistance to colonisation by SKT-1, and both SA and JA/ET signalling pathways combine in the signalling of induced resistance by CF. These results indicate that the response of A. thaliana is different from that found in root treatments with barley grain inoculum and CF from SKT-1. Copyright © 2011 Society of Chemical Industry.

  10. Phosphatidic acid is a major phospholipid class in reproductive organs of Arabidopsis thaliana.

    PubMed

    Yunus, Ian Sofian; Cazenave-Gassiot, Amaury; Liu, Yu-Chi; Lin, Ying-Chen; Wenk, Markus R; Nakamura, Yuki

    2015-01-01

    Phospholipids are the crucial components of biological membranes and signal transduction. Among different tissues, flower phospholipids are one of the least characterized features of plant lipidome. Here, we report that floral reproductive organs of Arabidopsis thaliana contain high levels of phosphatidic acid (PA), a known lipid second messenger. By using floral homeotic mutants enriched with specific floral organs, lipidomics study showed increased levels of PA species in ap3-3 mutant with enriched pistils. Accompanied gene expression study for 7 diacylglycerol kinases and 11 PA phosphatases revealed distinct floral organ specificity, suggesting an active phosphorylation/dephosphorylation between PA and diacylglycerol in flowers. Our results suggest that PA is a major phospholipid class in floral reproductive organs of A. thaliana.

  11. Delayed degradation of chlorophylls and photosynthetic proteins in Arabidopsis autophagy mutants during stress-induced leaf yellowing

    PubMed Central

    Sakuraba, Yasuhito; Lee, Sang-Hwa; Kim, Ye-Sol; Park, Ohkmae K.; Hörtensteiner, Stefan; Paek, Nam-Chon

    2014-01-01

    Plant autophagy, one of the essential proteolysis systems, balances proteome and nutrient levels in cells of the whole plant. Autophagy has been studied by analysing Arabidopsis thaliana autophagy-defective atg mutants, but the relationship between autophagy and chlorophyll (Chl) breakdown during stress-induced leaf yellowing remains unclear. During natural senescence or under abiotic-stress conditions, extensive cell death and early yellowing occurs in the leaves of atg mutants. A new finding is revealed that atg5 and atg7 mutants exhibit a functional stay-green phenotype under mild abiotic-stress conditions, but leaf yellowing proceeds normally in wild-type leaves under these conditions. Under mild salt stress, atg5 leaves retained high levels of Chls and all photosystem proteins and maintained a normal chloroplast structure. Furthermore, a double mutant of atg5 and non-functional stay-green nonyellowing1-1 (atg5 nye1-1) showed a much stronger stay-green phenotype than either single mutant. Taking these results together, it is proposed that autophagy functions in the non-selective catabolism of Chls and photosynthetic proteins during stress-induced leaf yellowing, in addition to the selective degradation of Chl–apoprotein complexes in the chloroplasts through the senescence-induced STAY-GREEN1/NYE1 and Chl catabolic enzymes. PMID:24510943

  12. The New Rga Locus Encodes a Negative Regulator of Gibberellin Response in Arabidopsis Thaliana

    PubMed Central

    Silverstone, A. L.; Mak, PYA.; Martinez, E. C.; Sun, T.

    1997-01-01

    We have identified a new locus involved in gibberellin (GA) signal transduction by screening for suppressors of the Arabidopsis thaliana GA biosynthetic mutant ga1-3. The locus is named RGA for repressor of ga1-3. Based on the recessive phenotype of the digenic rga/ga1-3 mutant, the wild-type gene product of RGA is probably a negative regulator of GA responses. Our screen for suppressors of ga1-3 identified 17 mutant alleles of RGA as well as 10 new mutant alleles at the previously identified SPY locus. The digenic (double homozygous) rga/ga1-3 mutants are able to partially repress several defects of ga1-3 including stem growth, leaf abaxial trichome initiation, flowering time, and apical dominance. The phenotype of the trigenic mutant (triple homozygous) rga/spy/ga1-3 shows that rga and spy have additive effects regulating flowering time, abaxial leaf trichome initiation and apical dominance. This trigenic mutant is similar to wild type with respect to each of these developmental events. Because rga/spy/ga1-3 is almost insensitive to GA for hypocotyl growth and its bolting stem is taller than the wild-type plant, the combined effects of the rga and spy mutations appear to allow GA-independent stem growth. Our studies indicate that RGA lies on a separate branch of the GA signal transduction pathway from SPY, which leads us to propose a modified model of the GA response pathway. PMID:9215910

  13. Starch synthase 4 is essential for coordination of starch granule formation with chloroplast division during Arabidopsis leaf expansion

    PubMed Central

    Crumpton-Taylor, Matilda; Pike, Marilyn; Lu, Kuan-Jen; Hylton, Christopher M; Feil, Regina; Eicke, Simona; Lunn, John E; Zeeman, Samuel C; Smith, Alison M

    2013-01-01

    Arabidopsis thaliana mutants lacking the SS4 isoform of starch synthase have strongly reduced numbers of starch granules per chloroplast, suggesting that SS4 is necessary for the normal generation of starch granules. To establish whether it plays a direct role in this process, we investigated the circumstances in which granules are formed in ss4 mutants. Starch granule numbers and distribution and the accumulation of starch synthase substrates and products were investigated during ss4 leaf development, and in ss4 mutants carrying mutations or transgenes that affect starch turnover or chloroplast volume. We found that immature ss4 leaves have no starch granules, but accumulate high concentrations of the starch synthase substrate ADPglucose. Granule numbers are partially restored by elevating the capacity for glucan synthesis (via expression of bacterial glycogen synthase) or by increasing the volumes of individual chloroplasts (via introduction of arc mutations). However, these granules are abnormal in distribution, size and shape. SS4 is an essential component of a mechanism that coordinates granule formation with chloroplast division during leaf expansion and determines the abundance and the flattened, discoid shape of leaf starch granules. PMID:23952675

  14. Quantitative expression analysis of selected transcription factors in pavement, basal and trichome cells of mature leaves from Arabidopsis thaliana.

    PubMed

    Schliep, Martin; Ebert, Berit; Simon-Rosin, Ulrike; Zoeller, Daniela; Fisahn, Joachim

    2010-05-01

    Gene expression levels of several transcription factors from Arabidopsis thaliana that were described previously to be involved in leaf development and trichome formation were analysed in trichome, basal and pavement cells of mature leaves. Single cell samples of these three cells types were collected by glass micro-capillaries. Real-time reverse transcription (RT)-PCR was used to analyse expression patterns of the following transcription factors: MYB23, MYB55, AtHB1, FILAMENTOUS FLOWER (FIL)/YABBY1 (YAB1), TRIPTYCHON (TRY) and CAPRICE (CPC). A difference in the expression patterns of TRY and CPC was revealed. Contrary to the CPC expression pattern, no transcripts of TRY could be detected in pavement cells. FIL/YAB1 was exclusively expressed in trichome cells. AtHB1 was highly expressed throughout all three cell types. MYB55 was higher expressed in basal cells than in trichome and pavement cells. MYB23 showed a pattern of low expression in pavement cells, medium in basal cells and high expression in trichomes. Expression patterns obtained by single cell sampling and real-time RT-PCR were compared to promoter GUS fusions of the selected transcription factors. Therefore, we regenerated two transgenic Arabidopsis lines that expressed the GUS reporter gene under control of the promoters of MYB55 and YAB1. In conclusion, despite their function in leaf morphogenesis, all six transcription factors were detected in mature leaves. Furthermore, single cell sampling and promoter GUS staining patterns demonstrated the predominant presence of MYB55 in basal cells as compared to pavement cells and trichomes.

  15. Quantitative expression analysis of selected transcription factors in pavement, basal and trichome cells of mature leaves from Arabidopsis thaliana

    PubMed Central

    Schliep, Martin; Ebert, Berit; Simon-Rosin, Ulrike; Zoeller, Daniela

    2010-01-01

    Gene expression levels of several transcription factors from Arabidopsis thaliana that were described previously to be involved in leaf development and trichome formation were analysed in trichome, basal and pavement cells of mature leaves. Single cell samples of these three cells types were collected by glass micro-capillaries. Real-time reverse transcription (RT)-PCR was used to analyse expression patterns of the following transcription factors: MYB23, MYB55, AtHB1, FILAMENTOUS FLOWER (FIL)/YABBY1 (YAB1), TRIPTYCHON (TRY) and CAPRICE (CPC). A difference in the expression patterns of TRY and CPC was revealed. Contrary to the CPC expression pattern, no transcripts of TRY could be detected in pavement cells. FIL/YAB1 was exclusively expressed in trichome cells. AtHB1 was highly expressed throughout all three cell types. MYB55 was higher expressed in basal cells than in trichome and pavement cells. MYB23 showed a pattern of low expression in pavement cells, medium in basal cells and high expression in trichomes. Expression patterns obtained by single cell sampling and real-time RT-PCR were compared to promoter GUS fusions of the selected transcription factors. Therefore, we regenerated two transgenic Arabidopsis lines that expressed the GUS reporter gene under control of the promoters of MYB55 and YAB1. In conclusion, despite their function in leaf morphogenesis, all six transcription factors were detected in mature leaves. Furthermore, single cell sampling and promoter GUS staining patterns demonstrated the predominant presence of MYB55 in basal cells as compared to pavement cells and trichomes. PMID:20101514

  16. Epistasis × environment interactions among Arabidopsis thaliana glucosinolate genes impact complex traits and fitness in the field.

    PubMed

    Kerwin, Rachel E; Feusier, Julie; Muok, Alise; Lin, Catherine; Larson, Brandon; Copeland, Daniel; Corwin, Jason A; Rubin, Matthew J; Francisco, Marta; Li, Baohua; Joseph, Bindu; Weinig, Cynthia; Kliebenstein, Daniel J

    2017-08-01

    Despite the growing number of studies showing that genotype × environment and epistatic interactions control fitness, the influences of epistasis × environment interactions on adaptive trait evolution remain largely uncharacterized. Across three field trials, we quantified aliphatic glucosinolate (GSL) defense chemistry, leaf damage, and relative fitness using mutant lines of Arabidopsis thaliana varying at pairs of causal aliphatic GSL defense genes to test the impact of epistatic and epistasis × environment interactions on adaptive trait variation. We found that aliphatic GSL accumulation was primarily influenced by additive and epistatic genetic variation, leaf damage was primarily influenced by environmental variation and relative fitness was primarily influenced by epistasis and epistasis × environment interactions. Epistasis × environment interactions accounted for up to 48% of the relative fitness variation in the field. At a single field site, the impact of epistasis on relative fitness varied significantly over 2 yr, showing that epistasis × environment interactions within a location can be temporally dynamic. These results suggest that the environmental dependency of epistasis can profoundly influence the response to selection, shaping the adaptive trajectories of natural populations in complex ways, and deserves further consideration in future evolutionary studies. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  17. Probing the Reproducibility of Leaf Growth and Molecular Phenotypes: A Comparison of Three Arabidopsis Accessions Cultivated in Ten Laboratories1[W

    PubMed Central

    Massonnet, Catherine; Vile, Denis; Fabre, Juliette; Hannah, Matthew A.; Caldana, Camila; Lisec, Jan; Beemster, Gerrit T.S.; Meyer, Rhonda C.; Messerli, Gaëlle; Gronlund, Jesper T.; Perkovic, Josip; Wigmore, Emma; May, Sean; Bevan, Michael W.; Meyer, Christian; Rubio-Díaz, Silvia; Weigel, Detlef; Micol, José Luis; Buchanan-Wollaston, Vicky; Fiorani, Fabio; Walsh, Sean; Rinn, Bernd; Gruissem, Wilhelm; Hilson, Pierre; Hennig, Lars; Willmitzer, Lothar; Granier, Christine

    2010-01-01

    A major goal of the life sciences is to understand how molecular processes control phenotypes. Because understanding biological systems relies on the work of multiple laboratories, biologists implicitly assume that organisms with the same genotype will display similar phenotypes when grown in comparable conditions. We investigated to what extent this holds true for leaf growth variables and metabolite and transcriptome profiles of three Arabidopsis (Arabidopsis thaliana) genotypes grown in 10 laboratories using a standardized and detailed protocol. A core group of four laboratories generated similar leaf growth phenotypes, demonstrating that standardization is possible. But some laboratories presented significant differences in some leaf growth variables, sometimes changing the genotype ranking. Metabolite profiles derived from the same leaf displayed a strong genotype × environment (laboratory) component. Genotypes could be separated on the basis of their metabolic signature, but only when the analysis was limited to samples derived from one laboratory. Transcriptome data revealed considerable plant-to-plant variation, but the standardization ensured that interlaboratory variation was not considerably larger than intralaboratory variation. The different impacts of the standardization on phenotypes and molecular profiles could result from differences of temporal scale between processes involved at these organizational levels. Our findings underscore the challenge of describing, monitoring, and precisely controlling environmental conditions but also demonstrate that dedicated efforts can result in reproducible data across multiple laboratories. Finally, our comparative analysis revealed that small variations in growing conditions (light quality principally) and handling of plants can account for significant differences in phenotypes and molecular profiles obtained in independent laboratories. PMID:20200072

  18. The AraGWAS Catalog: a curated and standardized Arabidopsis thaliana GWAS catalog

    PubMed Central

    Togninalli, Matteo; Seren, Ümit; Meng, Dazhe; Fitz, Joffrey; Nordborg, Magnus; Weigel, Detlef

    2018-01-01

    Abstract The abundance of high-quality genotype and phenotype data for the model organism Arabidopsis thaliana enables scientists to study the genetic architecture of many complex traits at an unprecedented level of detail using genome-wide association studies (GWAS). GWAS have been a great success in A. thaliana and many SNP-trait associations have been published. With the AraGWAS Catalog (https://aragwas.1001genomes.org) we provide a publicly available, manually curated and standardized GWAS catalog for all publicly available phenotypes from the central A. thaliana phenotype repository, AraPheno. All GWAS have been recomputed on the latest imputed genotype release of the 1001 Genomes Consortium using a standardized GWAS pipeline to ensure comparability between results. The catalog includes currently 167 phenotypes and more than 222 000 SNP-trait associations with P < 10−4, of which 3887 are significantly associated using permutation-based thresholds. The AraGWAS Catalog can be accessed via a modern web-interface and provides various features to easily access, download and visualize the results and summary statistics across GWAS. PMID:29059333

  19. Complete nucleotide sequence of spring beauty latent virus, a bromovirus infectious to Arabidopsis thaliana.

    PubMed

    Fujisaki, K; Hagihara, F; Kaido, M; Mise, K; Okuno, T

    2003-01-01

    Spring beauty latent virus (SBLV), a bromovirus, systemically and efficiently infected Arabidopsis thaliana, whereas the well-studied bromoviruses brome mosaic virus (BMV) and cowpea chlorotic mottle virus (CCMV) did not infect and poorly infected A. thaliana, respectively. We constructed biologically active cDNA clones of SBLV genomic RNAs and determined their complete nucleotide sequences. Interestingly, SBLV RNA3 contains both the box B motif in the intercistronic region, as does BMV, and the subgenomic promoter-like sequence in the 5' noncoding region, as does CCMV. Sequence comparisons of SBLV, BMV, CCMV, and broad bean mottle virus demonstrated that SBLV is closely related to BMV and CCMV.

  20. ALA10, a Phospholipid Flippase, Controls FAD2/FAD3 Desaturation of Phosphatidylcholine in the ER and Affects Chloroplast Lipid Composition in Arabidopsis thaliana1

    PubMed Central

    Sautron, Emeline; Boudiere, Laurence; Michaud, Morgane; Dubots, Emmanuelle; Albrieux, Catherine; Marechal, Eric; Jouhet, Juliette

    2016-01-01

    The biogenesis of photosynthetic membranes relies on galactoglycerolipids, which are synthesized via pathways that are dispatched over several cell compartments. This membrane biogenesis requires both trafficking of lipid intermediates and a tight homeostatic regulation. In this work, we address the role of ALA10 (for aminophospholipid ATPase), a P4-type ATPase, in a process counteracting the monogalactosyldiacylglycerol (MGDG) shortage in Arabidopsis (Arabidopsis thaliana) leaves. ALA10 can interact with protein partners, ALIS1 (for ALA-interacting subunit1) or ALIS5, leading to differential endomembrane localizations of the interacting proteins, close to the plasma membrane with ALIS1 or to chloroplasts with ALIS5. ALA10 interacts also with FATTY ACID DESATURASE2 (FAD2), and modification of ALA10 expression affects phosphatidylcholine (PC) fatty acyl desaturation by disturbing the balance between FAD2 and FAD3 activities. Modulation of ALA10 expression downstream impacts the fatty acyl composition of chloroplast PC. ALA10 expression also enhances leaf growth and improves the MGDG-PC ratio, possibly through MGDG SYNTHASE1 (MGD1) activation by phosphatidic acid. The positive effect of ALA10 on leaf development is significant in conditions such as upon treatment of plants with Galvestine-1, an inhibitor of MGDG synthases, or when plants are grown at chilling temperature. PMID:26620528

  1. Complex I-complex II ratio strongly differs in various organs of Arabidopsis thaliana.

    PubMed

    Peters, Katrin; Niessen, Markus; Peterhänsel, Christoph; Späth, Bettina; Hölzle, Angela; Binder, Stefan; Marchfelder, Anita; Braun, Hans-Peter

    2012-06-01

    In most studies, amounts of protein complexes of the oxidative phosphorylation (OXPHOS) system in different organs or tissues are quantified on the basis of isolated mitochondrial fractions. However, yield of mitochondrial isolations might differ with respect to tissue type due to varying efficiencies of cell disruption during organelle isolation procedures or due to tissue-specific properties of organelles. Here we report an immunological investigation on the ratio of the OXPHOS complexes in different tissues of Arabidopsis thaliana which is based on total protein fractions isolated from five Arabidopsis organs (leaves, stems, flowers, roots and seeds) and from callus. Antibodies were generated against one surface exposed subunit of each of the five OXPHOS complexes and used for systematic immunoblotting experiments. Amounts of all complexes are highest in flowers (likewise with respect to organ fresh weight or total protein content of the flower fraction). Relative amounts of protein complexes in all other fractions were determined with respect to their amounts in flowers. Our investigation reveals high relative amounts of complex I in green organs (leaves and stems) but much lower amounts in non-green organs (roots, callus tissue). In contrast, complex II only is represented by low relative amounts in green organs but by significantly higher amounts in non-green organs, especially in seeds. In fact, the complex I-complex II ratio differs by factor 37 between callus and leaf, indicating drastic differences in electron entry into the respiratory chain in these two fractions. Variation in amounts concerning complexes III, IV and V was less pronounced in different Arabidopsis tissues (quantification of complex V in leaves was not meaningful due to a cross-reaction of the antibody with the chloroplast form of this enzyme). Analyses were complemented by in gel activity measurements for the protein complexes of the OXPHOS system and comparative 2D blue native/SDS PAGE

  2. DNA Gyrase Is the Target for the Quinolone Drug Ciprofloxacin in Arabidopsis thaliana.

    PubMed

    Evans-Roberts, Katherine M; Mitchenall, Lesley A; Wall, Melisa K; Leroux, Julie; Mylne, Joshua S; Maxwell, Anthony

    2016-02-12

    The Arabidopsis thaliana genome contains four genes that were originally annotated as potentially encoding DNA gyrase: ATGYRA, ATGYRB1, ATGYRB2, and ATGYRB3. Although we subsequently showed that ATGYRB3 does not encode a gyrase subunit, the other three genes potentially encode subunits of a plant gyrase. We also showed evidence for the existence of supercoiling activity in A. thaliana and that the plant is sensitive to quinolone and aminocoumarin antibiotics, compounds that target DNA gyrase in bacteria. However, it was not possible at that time to show whether the A. thaliana genes encoded an active gyrase enzyme, nor whether that enzyme is indeed the target for the quinolone and aminocoumarin antibiotics. Here we show that an A. thaliana mutant resistant to the quinolone drug ciprofloxacin has a point mutation in ATGYRA. Moreover we show that, as in bacteria, the quinolone-sensitive (wild-type) allele is dominant to the resistant gene. Further we have heterologously expressed ATGYRA and ATGYRB2 in a baculovirus expression system and shown supercoiling activity of the partially purified enzyme. Expression/purification of the quinolone-resistant A. thaliana gyrase yields active enzyme that is resistant to ciprofloxacin. Taken together these experiments now show unequivocally that A. thaliana encodes an organelle-targeted DNA gyrase that is the target of the quinolone drug ciprofloxacin; this has important consequences for plant physiology and the development of herbicides. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. Model-based analysis of Arabidopsis leaf epidermal cells reveals distinct division and expansion patterns for pavement and guard cells.

    PubMed

    Asl, Leila Kheibarshekan; Dhondt, Stijn; Boudolf, Véronique; Beemster, Gerrit T S; Beeckman, Tom; Inzé, Dirk; Govaerts, Willy; De Veylder, Lieven

    2011-08-01

    To efficiently capture sunlight for photosynthesis, leaves typically develop into a flat and thin structure. This development is driven by cell division and expansion, but the individual contribution of these processes is currently unknown, mainly because of the experimental difficulties to disentangle them in a developing organ, due to their tight interconnection. To circumvent this problem, we built a mathematic model that describes the possible division patterns and expansion rates for individual epidermal cells. This model was used to fit experimental data on cell numbers and sizes obtained over time intervals of 1 d throughout the development of the first leaf pair of Arabidopsis (Arabidopsis thaliana). The parameters were obtained by a derivative-free optimization method that minimizes the differences between the predicted and experimentally observed cell size distributions. The model allowed us to calculate probabilities for a cell to divide into guard or pavement cells, the maximum size at which it can divide, and its average cell division and expansion rates at each point during the leaf developmental process. Surprisingly, average cell cycle duration remained constant throughout leaf development, whereas no evidence for a maximum cell size threshold for cell division of pavement cells was found. Furthermore, the model predicted that neighboring cells of different sizes within the epidermis expand at distinctly different relative rates, which could be verified by direct observations. We conclude that cell division seems to occur independently from the status of cell expansion, whereas the cell cycle might act as a timer rather than as a size-regulated machinery.

  4. The rhizobacterium Variovorax paradoxus 5C-2, containing ACC deaminase, promotes growth and development of Arabidopsis thaliana via an ethylene-dependent pathway

    PubMed Central

    Dodd, Ian C.

    2013-01-01

    Many plant-growth-promoting rhizobacteria (PGPR) associated with plant roots contain the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase and can metabolize ACC, the immediate precursor of the plant hormone ethylene, thereby decreasing plant ethylene production and increasing plant growth. However, relatively few studies have explicitly linked ethylene emission and/or action to growth promotion in these plant–microbe interactions. This study examined effects of the PGPR Variovorax paradoxus 5C-2 containing ACC deaminase on the growth and development of Arabidopsis thaliana using wild-type (WT) plants and several ethylene-related mutants (etr1-1, ein2-1, and eto1-1). Soil inoculation with V. paradoxus 5C-2 promoted growth (leaf area and shoot biomass) of WT plants and the ethylene-overproducing mutant eto1-1, and also enhanced floral initiation of WT plants by 2.5 days. However, these effects were not seen in ethylene-insensitive mutants (etr1-1 and ein2-1) even though bacterial colonization of the root system was similar. Furthermore, V. paradoxus 5C-2 decreased ACC concentrations of rosette leaves of WT plants by 59% and foliar ethylene emission of both WT plants and eto1-1 mutants by 42 and 37%, respectively. Taken together, these results demonstrate that a fully functional ethylene signal transduction pathway is required for V. paradoxus 5C-2 to stimulate leaf growth and flowering of A. thaliana. PMID:23404897

  5. The rhizobacterium Variovorax paradoxus 5C-2, containing ACC deaminase, promotes growth and development of Arabidopsis thaliana via an ethylene-dependent pathway.

    PubMed

    Chen, Lin; Dodd, Ian C; Theobald, Julian C; Belimov, Andrey A; Davies, William J

    2013-04-01

    Many plant-growth-promoting rhizobacteria (PGPR) associated with plant roots contain the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase and can metabolize ACC, the immediate precursor of the plant hormone ethylene, thereby decreasing plant ethylene production and increasing plant growth. However, relatively few studies have explicitly linked ethylene emission and/or action to growth promotion in these plant-microbe interactions. This study examined effects of the PGPR Variovorax paradoxus 5C-2 containing ACC deaminase on the growth and development of Arabidopsis thaliana using wild-type (WT) plants and several ethylene-related mutants (etr1-1, ein2-1, and eto1-1). Soil inoculation with V. paradoxus 5C-2 promoted growth (leaf area and shoot biomass) of WT plants and the ethylene-overproducing mutant eto1-1, and also enhanced floral initiation of WT plants by 2.5 days. However, these effects were not seen in ethylene-insensitive mutants (etr1-1 and ein2-1) even though bacterial colonization of the root system was similar. Furthermore, V. paradoxus 5C-2 decreased ACC concentrations of rosette leaves of WT plants by 59% and foliar ethylene emission of both WT plants and eto1-1 mutants by 42 and 37%, respectively. Taken together, these results demonstrate that a fully functional ethylene signal transduction pathway is required for V. paradoxus 5C-2 to stimulate leaf growth and flowering of A. thaliana.

  6. Arabidopsis Class I and Class II TCP Transcription Factors Regulate Jasmonic Acid Metabolism and Leaf Development Antagonistically1[C][W

    PubMed Central

    Danisman, Selahattin; van der Wal, Froukje; Dhondt, Stijn; Waites, Richard; de Folter, Stefan; Bimbo, Andrea; van Dijk, Aalt DJ; Muino, Jose M.; Cutri, Lucas; Dornelas, Marcelo C.; Angenent, Gerco C.; Immink, Richard G.H.

    2012-01-01

    TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR1 (TCP) transcription factors control developmental processes in plants. The 24 TCP transcription factors encoded in the Arabidopsis (Arabidopsis thaliana) genome are divided into two classes, class I and class II TCPs, which are proposed to act antagonistically. We performed a detailed phenotypic analysis of the class I tcp20 mutant, showing an increase in leaf pavement cell sizes in 10-d-old seedlings. Subsequently, a glucocorticoid receptor induction assay was performed, aiming to identify potential target genes of the TCP20 protein during leaf development. The LIPOXYGENASE2 (LOX2) and class I TCP9 genes were identified as TCP20 targets, and binding of TCP20 to their regulatory sequences could be confirmed by chromatin immunoprecipitation analyses. LOX2 encodes for a jasmonate biosynthesis gene, which is also targeted by class II TCP proteins that are under the control of the microRNA JAGGED AND WAVY (JAW), although in an antagonistic manner. Mutation of TCP9, the second identified TCP20 target, resulted in increased pavement cell sizes during early leaf developmental stages. Analysis of senescence in the single tcp9 and tcp20 mutants and the tcp9tcp20 double mutants showed an earlier onset of this process in comparison with wild-type control plants in the double mutant only. Both the cell size and senescence phenotypes are opposite to the known class II TCP mutant phenotype in JAW plants. Altogether, these results point to an antagonistic function of class I and class II TCP proteins in the control of leaf development via the jasmonate signaling pathway. PMID:22718775

  7. Characterization of a thermostable β-glucuronidase from Thermotoga maritima expressed in Arabidopsis thaliana.

    PubMed

    Xu, Jing; Tian, Yong-Sheng; Peng, Ri-He; Zhu, Bo; Gao, Jian-Jie; Yao, Quan-Hong

    2012-09-01

    TmGUSI, a gene identical to that encoding a thermostable β-glucuronidase in the hyperthermophilic anaerobe Thermotoga maritima, has been synthesized using a PCR-based two-step DNA synthesis and codon optimization for plants, and expressed in both Escherichia coli and Arabidopsis thaliana. TmGUSI expressed in transformed E. coli cells exhibited maximum hydrolytic activity at 65 °C and pH 6.5 and retained more than 80% activity after incubation at 85 °C for 30 min. TmGUSI activity in transgenic A. thaliana plants containing TmGUSI was also stable over the temperature range 65-80 °C. Our data suggest that β-glucuronidase from T. maritima can serve as a useful thermostable marker in higher plants.

  8. The FANTASTIC FOUR proteins influence shoot meristem size in Arabidopsis thaliana

    PubMed Central

    2010-01-01

    Background Throughout their lives plants produce new organs from groups of pluripotent cells called meristems, located at the tips of the shoot and the root. The size of the shoot meristem is tightly controlled by a feedback loop, which involves the homeodomain transcription factor WUSCHEL (WUS) and the CLAVATA (CLV) proteins. This regulatory circuit is further fine-tuned by morphogenic signals such as hormones and sugars. Results Here we show that a family of four plant-specific proteins, encoded by the FANTASTIC FOUR (FAF) genes, has the potential to regulate shoot meristem size in Arabidopsis thaliana. FAF2 and FAF4 are expressed in the centre of the shoot meristem, overlapping with the site of WUS expression. Consistent with a regulatory interaction between the FAF gene family and WUS, our experiments indicate that the FAFs can repress WUS, which ultimately leads to an arrest of meristem activity in FAF overexpressing lines. The finding that meristematic expression of FAF2 and FAF4 is under negative control by CLV3 further supports the hypothesis that the FAFs are modulators of the genetic circuit that regulates the meristem. Conclusion This study reports the initial characterization of the Arabidopsis thaliana FAF gene family. Our data indicate that the FAF genes form a plant specific gene family, the members of which have the potential to regulate the size of the shoot meristem by modulating the CLV3-WUS feedback loop. PMID:21176196

  9. The FANTASTIC FOUR proteins influence shoot meristem size in Arabidopsis thaliana.

    PubMed

    Wahl, Vanessa; Brand, Luise H; Guo, Ya-Long; Schmid, Markus

    2010-12-22

    Throughout their lives plants produce new organs from groups of pluripotent cells called meristems, located at the tips of the shoot and the root. The size of the shoot meristem is tightly controlled by a feedback loop, which involves the homeodomain transcription factor WUSCHEL (WUS) and the CLAVATA (CLV) proteins. This regulatory circuit is further fine-tuned by morphogenic signals such as hormones and sugars. Here we show that a family of four plant-specific proteins, encoded by the FANTASTIC FOUR (FAF) genes, has the potential to regulate shoot meristem size in Arabidopsis thaliana. FAF2 and FAF4 are expressed in the centre of the shoot meristem, overlapping with the site of WUS expression. Consistent with a regulatory interaction between the FAF gene family and WUS, our experiments indicate that the FAFs can repress WUS, which ultimately leads to an arrest of meristem activity in FAF overexpressing lines. The finding that meristematic expression of FAF2 and FAF4 is under negative control by CLV3 further supports the hypothesis that the FAFs are modulators of the genetic circuit that regulates the meristem. This study reports the initial characterization of the Arabidopsis thaliana FAF gene family. Our data indicate that the FAF genes form a plant specific gene family, the members of which have the potential to regulate the size of the shoot meristem by modulating the CLV3-WUS feedback loop.

  10. Silica nanoparticle phytotoxicity to Arabidopsis thaliana.

    PubMed

    Slomberg, Danielle L; Schoenfisch, Mark H

    2012-09-18

    The phytotoxicity of silica nanoparticles (SiNPs) was evaluated as a function of particle size (14, 50, and 200 nm), concentration (250 and 1000 mg L(-1)), and surface composition toward Arabidopsis thaliana plants grown hydroponically for 3 and 6 weeks. Reduced development and chlorosis were observed for plants exposed to highly negative SiNPs (-20.3 and -31.9 mV for the 50 and 200 nm SiNPs, respectively) regardless of particle concentration when not controlling pH of the hydroponic medium, which resulted in increased alkalinity (~pH 8). Particles were no longer toxic to the plants at either concentration upon calcination or removal of surface silanols from the SiNP surface, or adjusting the pH of the growth medium to pH 5.8. The phytotoxic effects observed for the negatively charged 50 and 200 nm SiNPs were attributed to pH effects and the adsorption of macro- and micro-nutrients to the silica surface. Size-dependent uptake of the nanoparticles by the plants was confirmed using transmission electron microscopy (TEM) and inductively coupled plasma-optical emission spectroscopy (ICP-OES) with plant roots containing 32.0, 1.85, and 7.00 × 10(-3) mg Si·kg tissue(-1)/nm(3) (normalized for SiNP volume) for the 14, 50, and 200 nm SiNPs respectively, after 6 weeks exposure at 1000 ppm (pH 5.8). This study demonstrates that the silica scaffolds are not phytotoxic up to 1000 ppm despite significant uptake of the SiNPs (14, 50, and 200 nm) into the root system of A. thaliana.

  11. The Hidden Geometries of the Arabidopsis thaliana Epidermis

    PubMed Central

    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 µm2 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 µm2) 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

  12. Paenibacillus pabuli strain P7S promotes plant growth and induces anthocyanin accumulation in Arabidopsis thaliana.

    PubMed

    Trinh, Cao Son; Jeong, Chan Young; Lee, Won Je; Truong, Hai An; Chung, Namhyun; Han, Juhyeong; Hong, Suk-Whan; Lee, Hojoung

    2018-06-01

    In this study, a novel plant growth-promoting rhizobacteria (PGPR), the bacterial strain Paenibacillus pabuli P7S (PP7S), showed promising plant growth-promoting effects. Furthermore, it induced anthocyanin accumulation in Arabidopsis. When co-cultivated with PP7S, there was a significant increase in anthocyanin content and biomass of Arabidopsis seedlings compared with those of the control. The quantitative reverse transcription-polymerase chain reaction analysis revealed higher expression of many key genes regulating anthocyanin and flavonoid biosynthesis pathways in PP7S-treated seedlings when compared with that of the control. Furthermore, higher expression of pathogen-related genes and microbe-associated molecular pattern genes was also observed in response to PP7S, indicating that the PGPR triggered the induced systemic response (ISR) in A. thaliana. These results suggest that PP7S promotes plant growth in A. thaliana and increases anthocyanin biosynthesis by triggering specific ISRs in plant. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  13. A map of local adaptation in Arabidopsis thaliana.

    PubMed

    Fournier-Level, A; Korte, A; Cooper, M D; Nordborg, M; Schmitt, J; Wilczek, A M

    2011-10-07

    Local adaptation is critical for species persistence in the face of rapid environmental change, but its genetic basis is not well understood. Growing the model plant Arabidopsis thaliana in field experiments in four sites across the species' native range, we identified candidate loci for local adaptation from a genome-wide association study of lifetime fitness in geographically diverse accessions. Fitness-associated loci exhibited both geographic and climatic signatures of local adaptation. Relative to genomic controls, high-fitness alleles were generally distributed closer to the site where they increased fitness, occupying specific and distinct climate spaces. Independent loci with different molecular functions contributed most strongly to fitness variation in each site. Independent local adaptation by distinct genetic mechanisms may facilitate a flexible evolutionary response to changing environment across a species range.

  14. Multimodal nonlinear imaging of arabidopsis thaliana root cell

    NASA Astrophysics Data System (ADS)

    Jang, Bumjoon; Lee, Sung-Ho; Woo, Sooah; Park, Jong-Hyun; Lee, Myeong Min; Park, Seung-Han

    2017-07-01

    Nonlinear optical microscopy has enabled the possibility to explore inside the living organisms. It utilizes ultrashort laser pulse with long wavelength (greater than 800nm). Ultrashort pulse produces high peak power to induce nonlinear optical phenomenon such as two-photon excitation fluorescence (TPEF) and harmonic generations in the medium while maintaining relatively low average energy pre area. In plant developmental biology, confocal microscopy is widely used in plant cell imaging after the development of biological fluorescence labels in mid-1990s. However, fluorescence labeling itself affects the sample and the sample deviates from intact condition especially when labelling the entire cell. In this work, we report the dynamic images of Arabidopsis thaliana root cells. This demonstrates the multimodal nonlinear optical microscopy is an effective tool for long-term plant cell imaging.

  15. Active suppression of a leaf meristem orchestrates determinate leaf growth

    PubMed Central

    Alvarez, John Paul; Furumizu, Chihiro; Efroni, Idan; Eshed, Yuval; Bowman, John L

    2016-01-01

    Leaves are flat determinate organs derived from indeterminate shoot apical meristems. The presence of a specific leaf meristem is debated, as anatomical features typical of meristems are not present in leaves. Here we demonstrate that multiple NGATHA (NGA) and CINCINNATA-class-TCP (CIN-TCP) transcription factors act redundantly, shortly after leaf initiation, to gradually restrict the activity of a leaf meristem in Arabidopsis thaliana to marginal and basal domains, and that their absence confers persistent marginal growth to leaves, cotyledons and floral organs. Following primordia initiation, the restriction of the broadly acting leaf meristem to the margins is mediated by the juxtaposition of adaxial and abaxial domains and maintained by WOX homeobox transcription factors, whereas other marginal elaboration genes are dispensable for its maintenance. This genetic framework parallels the morphogenetic program of shoot apical meristems and may represent a relic of an ancestral shoot system from which seed plant leaves evolved. DOI: http://dx.doi.org/10.7554/eLife.15023.001 PMID:27710768

  16. Gravitational stress-induced changes in the phosphoproteom of Arabidopsis thaliana cell cultures

    NASA Astrophysics Data System (ADS)

    Hampp, Ruediger; Hausmann, Niklas; Neef, Maren; Schuetz, Wolfgang; Madlung, Johannes; Fladerer, Claudia; Nordheim, Alfred; Costa, Alex; Barjaktarovic, Zarko

    Callus cell cultures of Arabidopsis thaliana respond to changes in gravitational field strengths by changes in protein expression. Using ESI-MS/MS for proteins with differential abundance after separation by 2D-PAGE, 28 spots which changed reproducibly and significantly (P¡0.05) in amount after 2h of hypergravity (18 up-, 10 down-regulated) could be identified. The corre-sponding proteins were largely involved in stress responses, including detoxification of reactive oxygen species (ROS; Barjaktaroviá et al., J. Exptl. Bot. 58:4357 (2007)). In the present study, c we extended these investigations to phosphorylated proteins. For this purpose, callus cell cul-tures of Arabidopsis thaliana were exposed to hypergravity (8 g) and simulated weightlessness (random positioning; RP) for up to 30 min, a period of time which yielded most reliable data. First changes, however, were visible as early as 10 min after start of treatment. Out of the protein spots altered in phosphorylation, we were able to identify 24 from those responding to random positioning and 12 which responded to 8 g. The respective proteins are involved in scavenging and detoxification of ROS (32Most recent data obtained from parabolic flights indicate that exposure times to g of as little as 20 s are sufficient to alter the phosphorylation of proteins pattern. This is accompanied by changes in the cellular Ca2+ and H2O2 contents.

  17. Century-scale Methylome Stability in a Recently Diverged Arabidopsis thaliana Lineage

    PubMed Central

    Müller, Jonas; Stegle, Oliver; Meyer, Rhonda C.; Wang, George; Schneeberger, Korbinian; Fitz, Joffrey; Altmann, Thomas; Bergelson, Joy; Borgwardt, Karsten; Weigel, Detlef

    2015-01-01

    There has been much excitement about the possibility that exposure to specific environments can induce an ecological memory in the form of whole-sale, genome-wide epigenetic changes that are maintained over many generations. In the model plant Arabidopsis thaliana, numerous heritable DNA methylation differences have been identified in greenhouse-grown isogenic lines, but it remains unknown how natural, highly variable environments affect the rate and spectrum of such changes. Here we present detailed methylome analyses in a geographically dispersed A. thaliana population that constitutes a collection of near-isogenic lines, diverged for at least a century from a common ancestor. Methylome variation largely reflected genetic distance, and was in many aspects similar to that of lines raised in uniform conditions. Thus, even when plants are grown in varying and diverse natural sites, genome-wide epigenetic variation accumulates mostly in a clock-like manner, and epigenetic divergence thus parallels the pattern of genome-wide DNA sequence divergence. PMID:25569172

  18. Expression of pH-sensitive green fluorescent protein in Arabidopsis thaliana

    NASA Technical Reports Server (NTRS)

    Moseyko, N.; Feldman, L. J.

    2001-01-01

    This is the first report on using green fluorescent protein (GFP) as a pH reporter in plants. Proton fluxes and pH regulation play important roles in plant cellular activity and therefore, it would be extremely helpful to have a plant gene reporter system for rapid, non-invasive visualization of intracellular pH changes. In order to develop such a system, we constructed three vectors for transient and stable transformation of plant cells with a pH-sensitive derivative of green fluorescent protein. Using these vectors, transgenic Arabidopsis thaliana and tobacco plants were produced. Here the application of pH-sensitive GFP technology in plants is described and, for the first time, the visualization of pH gradients between different developmental compartments in intact whole-root tissues of A. thaliana is reported. The utility of pH-sensitive GFP in revealing rapid, environmentally induced changes in cytoplasmic pH in roots is also demonstrated.

  19. Gene Mining for Proline Based Signaling Proteins in Cell Wall of Arabidopsis thaliana

    PubMed Central

    Ihsan, Muhammad Z.; Ahmad, Samina J. N.; Shah, Zahid Hussain; Rehman, Hafiz M.; Aslam, Zubair; Ahuja, Ishita; Bones, Atle M.; Ahmad, Jam N.

    2017-01-01

    The cell wall (CW) as a first line of defense against biotic and abiotic stresses is of primary importance in plant biology. The proteins associated with cell walls play a significant role in determining a plant's sustainability to adverse environmental conditions. In this work, the genes encoding cell wall proteins (CWPs) in Arabidopsis were identified and functionally classified using geneMANIA and GENEVESTIGATOR with published microarrays data. This yielded 1605 genes, out of which 58 genes encoded proline-rich proteins (PRPs) and glycine-rich proteins (GRPs). Here, we have focused on the cellular compartmentalization, biological processes, and molecular functioning of proline-rich CWPs along with their expression at different plant developmental stages. The mined genes were categorized into five classes on the basis of the type of PRPs encoded in the cell wall of Arabidopsis thaliana. We review the domain structure and function of each class of protein, many with respect to the developmental stages of the plant. We have then used networks, hierarchical clustering and correlations to analyze co-expression, co-localization, genetic, and physical interactions and shared protein domains of these PRPs. This has given us further insight into these functionally important CWPs and identified a number of potentially new cell-wall related proteins in A. thaliana. PMID:28289422

  20. Stereoselective phytotoxicity of HCH mediated by photosynthetic and antioxidant defense systems in Arabidopsis thaliana.

    PubMed

    Zhang, Qiong; Zhou, Cong; Zhang, Quan; Qian, Haifeng; Liu, Weiping; Zhao, Meirong

    2013-01-01

    Hexachlorocyclohexane (HCH) has been used for plant protection and sanitation world-widely, and its isomers have been detected in water, soil, and air as well as in vegetation. As a sink for lipophilic pollutants, vegetation is very important for the degradation and fate of organic contamination; however, little was known about their phytotoxicity and mechanisms of toxic effect. In this study, the stereoselective phototoxicity of four isomers (α, β, γ, and δ) of HCHs mediated by independent as well as interconnecting systems of photosynthesis and enzymatic antioxidant defense system in Arabidopsis thaliana were assessed. Our results revealed that all the HCHs not only stimulated the activities of catalase (CAT) and peroxidase (POD), but also inhibited the activity of superoxide dismutase (SOD). In photosynthesis system, the photosynthetic efficiency of PSI and PSII were all down regulated. Meanwhile, results from both systems showed that δ-HCH was the most toxic one, while α-HCH the least in Arabidopsis thaliana. For the first time, stereoselective effects of different isomers of HCH in plant were demonstrated. And the results suggest that it requires further research to fully elucidate the environmental toxicity and their mechanisms.

  1. Defining the core Arabidopsis thaliana root microbiome

    PubMed Central

    Gehring, Jase; Malfatti, Stephanie; Tremblay, Julien; Engelbrektson, Anna; Kunin, Victor; del Rio, Tijana Glavina; Edgar, Robert C.; Eickhorst, Thilo; Ley, Ruth E.; Hugenholtz, Philip; Tringe, Susannah Green; Dangl, Jeffery L.

    2014-01-01

    Land plants associate with a root microbiota distinct from the complex microbial community present in surrounding soil. The microbiota colonizing therhizosphere(immediately surroundingthe root) and the endophytic compartment (within the root) contribute to plant growth, productivity, carbon sequestration and phytoremediation1-3. Colonization of the root occurs despite a sophisticated plant immune system4,5, suggesting finely tuned discrimination of mutualists and commensals from pathogens. Genetic principles governing the derivation of host-specific endophyte communities from soil communities are poorly understood. Here we report the pyrosequencing of the bacterial 16S ribosomal RNA gene of more than 600 Arabidopsis thaliana plants to test the hypotheses that the root rhizosphere and endophytic compartment microbiota of plants grown under controlled conditions in natural soils are sufficiently dependent on the host to remain consistent across different soil types and developmental stages, and sufficiently dependent on host genotype to vary between inbred Arabidopsis accessions. We describe different bacterial communities in two geochemically distinct bulk soils and in rhizosphere and endophytic compartments prepared from roots grown in these soils. The communities in each compartment are strongly influenced by soil type. Endophytic compartments from both soils feature overlapping, low-complexity communities that are markedly enriched in Actinobacteria and specific families from other phyla, notably Proteobacteria. Some bacteria vary quantitatively between plants of different developmental stage and genotype. Our rigorous definition of an endophytic compartment microbiome should facilitate controlled dissection of plantmicrobe interactions derived from complex soil communities. PMID:22859206

  2. Phytoremediation of the organic Xenobiotic simazine by p450-1a2 transgenic Arabidopsis thaliana plants.

    PubMed

    Azab, Ehab; Hegazy, Ahmad K; El-Sharnouby, Mohamed E; Abd Elsalam, Hassan E

    2016-01-01

    The potential use of human P450-transgenic plants for phytoremediation of pesticide contaminated soils was tested in laboratory and greenhouse experiments. The transgenic P450 CYP1A2 gene Arabidopsis thaliana plants metabolize number of herbicides, insecticides and industrial chemicals. The P450 isozymes CYP1A2 expressed in A. thaliana were examined regarding the herbicide simazine (SIM). Transgenic A. thaliana plants expressing CYP1A2 gene showed significant resistance to SIM supplemented either in plant growth medium or sprayed on foliar parts. The results showed that SIM produces harmful effect on both rosette diameter and primary root length of the wild type (WT) plants. In transgenic A. thaliana lines, the rosette diameter and primary root length were not affected by SIM concentrations used in this experiment. The results indicate that CYP1A2 can be used as a selectable marker for plant transformation, allowing efficient selection of transgenic lines in growth medium and/or in soil-grown plants. The transgenic A. thaliana plants exhibited a healthy growth using doses of up to 250 μmol SIM treatments, while the non-transgenic A. thaliana plants were severely damaged with doses above 50 μmol SIM treatments. The transgenic A. thaliana plants can be used as phytoremediator of environmental SIM contaminants.

  3. Acclimation responses of Arabidopsis thaliana to sustained phosphite treatments

    PubMed Central

    Berkowitz, Oliver

    2013-01-01

    Phosphite () induces a range of physiological and developmental responses in plants by disturbing the homeostasis of the macronutrient phosphate. Because of its close structural resemblance to phosphate, phosphite impairs the sensing, membrane transport, and subcellular compartmentation of phosphate. In addition, phosphite induces plant defence responses by an as yet unknown mode of action. In this study, the acclimation of Arabidopsis thaliana plants to a sustained phosphite supply in the growth medium was investigated and compared with plants growing under varying phosphate supplies. Unlike phosphate, phosphite did not suppress the formation of lateral roots in several Arabidopsis accessions. In addition, the expression of well-documented phosphate-starvation-induced genes, such as miRNA399d and At4, was not repressed by phosphite accumulation, whilst the induction of PHT1;1 and PAP1 was accentuated. Thus, a mimicking of phosphate by phosphite was not observed for these classical phosphate-starvation responses. Metabolomic analysis of phosphite-treated plants showed changes in several metabolite pools, most prominently those of aspartate, asparagine, glutamate, and serine. These alterations in amino acid pools provide novel insights for the understanding of phosphite-induced pathogen resistance. PMID:23404904

  4. Leaf expansion in Arabidopsis is controlled by a TCP-NGA regulatory module likely conserved in distantly related species.

    PubMed

    Ballester, Patricia; Navarrete-Gómez, Marisa; Carbonero, Pilar; Oñate-Sánchez, Luis; Ferrándiz, Cristina

    2015-09-01

    The NGATHA (NGA) clade of transcription factors (TFs) forms a small subfamily of four members in Arabidopsis thaliana. NGA genes act redundantly to direct the development of apical tissues in the gynoecium, where they have been shown to be essential for style and stigma specification. In addition, NGA genes have a more general role in controlling lateral organ growth. The four NGA genes in Arabidopsis are expressed in very similar domains, although little is known about the nature of their putative regulators. Here, we have identified a conserved region within the four NGA promoters that we have used as a bait to screen a yeast library, aiming to identify such NGA regulators. Three members of the TCP family of TFs, named after the founding factors TEOSINTE BRANCHED 1, CYCLOIDEA and PROLIFERATING CELL FACTOR 1 AND 2), were recovered from this screening, of which two [TCP2 and TCP3, members of the CINCINNATA (CIN) family of TCP genes (CIN-TCP) subclade] were shown to activate the NGA3 promoter in planta. We provide evidence that support that CIN-TCP genes are true regulators of NGA gene expression, and that part of the CIN-TCP role in leaf development is mediated by NGA upregulation. Moreover, we have found that this TCP-NGA regulatory interaction is likely conserved in angiosperms, including important crop species, for which the regulation of leaf development is a target for biotechnological improvement. © 2015 Scandinavian Plant Physiology Society.

  5. Regulation of Arabidopsis leaf hydraulics involves light-dependent phosphorylation of aquaporins in veins.

    PubMed

    Prado, Karine; Boursiac, Yann; Tournaire-Roux, Colette; Monneuse, Jean-Marc; Postaire, Olivier; Da Ines, Olivier; Schäffner, Anton R; Hem, Sonia; Santoni, Véronique; Maurel, Christophe

    2013-03-01

    The water status of plant leaves depends on the efficiency of the water supply, from the vasculature to inner tissues. This process is under hormonal and environmental regulation and involves aquaporin water channels. In Arabidopsis thaliana, the rosette hydraulic conductivity (Kros) is higher in darkness than it is during the day. Knockout plants showed that three plasma membrane intrinsic proteins (PIPs) sharing expression in veins (PIP1;2, PIP2;1, and PIP2;6) contribute to rosette water transport, and PIP2;1 can fully account for Kros responsiveness to darkness. Directed expression of PIP2;1 in veins of a pip2;1 mutant was sufficient to restore Kros. In addition, a positive correlation, in both wild-type and PIP2;1-overexpressing plants, was found between Kros and the osmotic water permeability of protoplasts from the veins but not from the mesophyll. Thus, living cells in veins form a major hydraulic resistance in leaves. Quantitative proteomic analyses showed that light-dependent regulation of Kros is linked to diphosphorylation of PIP2;1 at Ser-280 and Ser-283. Expression in pip2;1 of phosphomimetic and phosphorylation-deficient forms of PIP2;1 demonstrated that phosphorylation at these two sites is necessary for Kros enhancement under darkness. These findings establish how regulation of a single aquaporin isoform in leaf veins critically determines leaf hydraulics.

  6. Genome-wide Discovery of Circular RNAs in the Leaf and Seedling Tissues of Arabidopsis Thaliana

    PubMed Central

    Dou, Yongchao; Li, Shengjun; Yang, Weilong; Liu, Kan; Du, Qian; Ren, Guodong; Yu, Bin; Zhang, Chi

    2017-01-01

    Background: Recently, identification and functional studies of circular RNAs, a type of non-coding RNAs arising from a ligation of 3’ and 5’ ends of a linear RNA molecule, were conducted in mammalian cells with the development of RNA-seq technology. Method: Since compared with animals, studies on circular RNAs in plants are less thorough, a genome-wide identification of circular RNA candidates in Arabidopsis was conducted with our own developed bioinformatics tool to several existing RNA-seq datasets specifically for non-coding RNAs. Results: A total of 164 circular RNA candidates were identified from RNA-seq data, and 4 circular RNA transcripts, including both exonic and intronic circular RNAs, were experimentally validated. Interestingly, our results show that circular RNA transcripts are enriched in the photosynthesis system for the leaf tissue and correlated to the higher expression levels of their parent genes. Sixteen out of all 40 genes that have circular RNA candidates are related to the photosynthesis system, and out of the total 146 exonic circular RNA candidates, 63 are found in chloroplast. PMID:29081691

  7. ROP GTPase-mediated auxin signaling regulates pavement cell interdigitation in Arabidopsis thaliana.

    PubMed

    Lin, Deshu; Ren, Huibo; Fu, Ying

    2015-01-01

    In multicellular plant organs, cell shape formation depends on molecular switches to transduce developmental or environmental signals and to coordinate cell-to-cell communication. Plants have a specific subfamily of the Rho GTPase family, usually called Rho of Plants (ROP), which serve as a critical signal transducer involved in many cellular processes. In the last decade, important advances in the ROP-mediated regulation of plant cell morphogenesis have been made by using Arabidopsis thaliana leaf and cotyledon pavement cells. Especially, the auxin-ROP signaling networks have been demonstrated to control interdigitated growth of pavement cells to form jigsaw-puzzle shapes. Here, we review findings related to the discovery of this novel auxin-signaling mechanism at the cell surface. This signaling pathway is to a large extent independent of the well-known Transport Inhibitor Response (TIR)-Auxin Signaling F-Box (AFB) pathway, and instead requires Auxin Binding Protein 1 (ABP1) interaction with the plasma membrane-localized, transmembrane kinase (TMK) receptor-like kinase to regulate ROP proteins. Once activated, ROP influences cytoskeletal organization and inhibits endocytosis of the auxin transporter PIN1. The present review focuses on ROP signaling and its self-organizing feature allowing ROP proteins to serve as a bustling signal decoder and integrator for plant cell morphogenesis. © 2014 Institute of Botany, Chinese Academy of Sciences.

  8. Light-dependent intracellular positioning of mitochondria in Arabidopsis thaliana mesophyll cells.

    PubMed

    Islam, Md Sayeedul; Niwa, Yasuo; Takagi, Shingo

    2009-06-01

    Mitochondria, the power house of the cell, are one of the most dynamic cell organelles. Although there are several reports on actin- or microtubule-dependent movement of mitochondria in plant cells, intracellular positioning and motility of mitochondria under different light conditions remain open questions. Mitochondria were visualized in living Arabidopsis thaliana leaf cells using green fluorescent protein fused to a mitochondrion-targeting signal. In darkness, mitochondria were distributed randomly in palisade cells. In contrast, mitochondria accumulated along the periclinal walls, similar to the accumulation response of chloroplasts, when treated with weak blue light (470 nm, 4 micromol m(-2) s(-1)). Under strong blue light (100 micromol m(-2) s(-1)), mitochondria occupied the anticlinal positions similar to the avoidance response of chloroplasts and nuclei. While strong red light (660 nm, 100 micromol m(-2) s(-1)) induced the accumulation of mitochondria along the inner periclinal walls, green light exhibited little effect on the distribution of mitochondria. In addition, the mode of movement of individual mitochondria along the outer periclinal walls under different light conditions was precisely analyzed by time-lapse fluorescence microscopy. A gradual increase in the number of static mitochondria located in the vicinity of chloroplasts with a time period of blue light illumination clearly demonstrated the accumulation response of mitochondria. Light-induced co-localization of mitochondria with chloroplasts strongly suggested their mutual metabolic interactions. This is the first characterization of the light-dependent redistribution of mitochondria in plant cells.

  9. Heterochrony underpins natural variation in Cardamine hirsuta leaf form

    PubMed Central

    Cartolano, Maria; Pieper, Bjorn; Lempe, Janne; Tattersall, Alex; Huijser, Peter; Tresch, Achim; Darrah, Peter R.; Hay, Angela; Tsiantis, Miltos

    2015-01-01

    A key problem in biology is whether the same processes underlie morphological variation between and within species. Here, by using plant leaves as an example, we show that the causes of diversity at these two evolutionary scales can be divergent. Some species like the model plant Arabidopsis thaliana have simple leaves, whereas others like the A. thaliana relative Cardamine hirsuta bear complex leaves comprising leaflets. Previous work has shown that these interspecific differences result mostly from variation in local tissue growth and patterning. Now, by cloning and characterizing a quantitative trait locus (QTL) for C. hirsuta leaf shape, we find that a different process, age-dependent progression of leaf form, underlies variation in this trait within species. This QTL effect is caused by cis-regulatory variation in the floral repressor ChFLC, such that genotypes with low-expressing ChFLC alleles show both early flowering and accelerated age-dependent changes in leaf form, including faster leaflet production. We provide evidence that this mechanism coordinates leaf development with reproductive timing and may help to optimize resource allocation to the next generation. PMID:26243877

  10. Egg Laying of Cabbage White Butterfly (Pieris brassicae) on Arabidopsis thaliana Affects Subsequent Performance of the Larvae

    PubMed Central

    Blenn, Beatrice; Drechsler, Navina; Gershenzon, Jonathan; Kunze, Reinhard; Hilker, Monika

    2013-01-01

    Plant resistance to the feeding by herbivorous insects has recently been found to be positively or negatively influenced by prior egg deposition. Here we show how crucial it is to conduct experiments on plant responses to herbivory under conditions that simulate natural insect behaviour. We used a well-studied plant – herbivore system, Arabidopsis thaliana and the cabbage white butterfly Pieris brassicae, testing the effects of naturally laid eggs (rather than egg extracts) and allowing larvae to feed gregariously as they do naturally (rather than placing single larvae on plants). Under natural conditions, newly hatched larvae start feeding on their egg shells before they consume leaf tissue, but access to egg shells had no effect on subsequent larval performance in our experiments. However, young larvae feeding gregariously on leaves previously laden with eggs caused less feeding damage, gained less weight during the first 2 days, and suffered twice as high a mortality until pupation compared to larvae feeding on plants that had never had eggs. The concentration of the major anti-herbivore defences of A. thaliana, the glucosinolates, was not significantly increased by oviposition, but the amount of the most abundant member of this class, 4-methylsulfinylbutyl glucosinolate was 1.8-fold lower in larval-damaged leaves with prior egg deposition compared to damaged leaves that had never had eggs. There were also few significant changes in the transcript levels of glucosinolate metabolic genes, except that egg deposition suppressed the feeding-induced up-regulation of FMOGS-OX2, a gene encoding a flavin monooxygenase involved in the last step of 4-methylsulfinylbutyl glucosinolate biosynthesis. Hence, our study demonstrates that oviposition does increase A. thaliana resistance to feeding by subsequently hatching larvae, but this cannot be attributed simply to changes in glucosinolate content. PMID:23527243

  11. Trehalose-6-phosphate synthase 1 is not the only active TPS in Arabidopsis thaliana.

    PubMed

    Delorge, Ines; Figueroa, Carlos M; Feil, Regina; Lunn, John E; Van Dijck, Patrick

    2015-03-01

    Trehalose metabolism is essential for normal growth and development in higher plants. It is synthesized in a two-step pathway catalysed by TPS (trehalose-6-phosphate synthase) and trehalose phosphatase. Arabidopsis thaliana has 11 TPS or TPS-like proteins, which belong to two distinct clades: class I (AtTPS1-AtTPS4) and class II (AtTPS5-AtTPS11). Only AtTPS1 has previously been shown to have TPS activity. A. thaliana tps1∆ mutants fail to complete embryogenesis and rescued lines have stunted growth and delayed flowering, indicating that AtTPS1 is important throughout the life cycle. In the present study, we show that expression of AtTPS2 or AtTPS4 enables the yeast tps1∆ tps2∆ mutant to grow on glucose and accumulate Tre6P (trehalose 6-phosphate) and trehalose. Class II TPS genes did not complement the yeast mutant. Thus A. thaliana has at least three catalytically active TPS isoforms, suggesting that loss of Tre6P production might not be the only reason for the growth defects of A. thaliana tps1 mutants.

  12. The plant secondary metabolite citral alters water status and prevents seed formation in Arabidopsis thaliana.

    PubMed

    Graña, E; Díaz-Tielas, C; López-González, D; Martínez-Peñalver, A; Reigosa, M J; Sánchez-Moreiras, A M

    2016-05-01

    Based on previous results, which showed that the secondary metabolite citral causes disturbances to plant water status, the present study is focused on demonstrating and detailing these effects on the water-related parameters of Arabidopsis thaliana adult plants, and their impact on plant fitness. Clear evidence of effects on water status and fitness were observed: plants treated with 1200 and 2400 μm citral showed decreased RWC, reduced Ψs , increased Ψw and reduced stomatal opening, even 7 days after the beginning of the experiment. Plant protection signals, such as leaf rolling or increased anthocyanin content, were also detected in these plants. In contrast, 14 days after beginning the treatment, treated plants showed signs of citral-related damage. Moreover, the reproductive success of treated plants was critically compromised, with prematurely withered flowers and no silique or seed development. This effect of citral on fitness of adult plants suggests a promising application of this natural compound in weed management by reducing the weed seed bank in the soil. © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.

  13. SMZ/SNZ and gibberellin signaling are required for nitrate-elicited delay of flowering time in Arabidopsis thaliana.

    PubMed

    Gras, Diana E; Vidal, Elena A; Undurraga, Soledad F; Riveras, Eleodoro; Moreno, Sebastián; Dominguez-Figueroa, José; Alabadi, David; Blázquez, Miguel A; Medina, Joaquín; Gutiérrez, Rodrigo A

    2018-01-23

    The reproductive success of plants largely depends on the correct programming of developmental phase transitions, particularly the shift from vegetative to reproductive growth. The timing of this transition is finely regulated by the integration of an array of environmental and endogenous factors. Nitrogen is the mineral macronutrient that plants require in the largest amount, and as such its availability greatly impacts on many aspects of plant growth and development, including flowering time. We found that nitrate signaling interacts with the age-related and gibberellic acid pathways to control flowering time in Arabidopsis thaliana. We revealed that repressors of flowering time belonging to the AP2-type transcription factor family including SCHLAFMUTZE (SMZ) and SCHNARCHZAPFEN (SNZ) are important regulators of flowering time in response to nitrate. Our results support a model whereby nitrate activates SMZ and SNZ via the gibberellin pathway to repress flowering time in Arabidopsis thaliana. © The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  14. Cell wall proteome analysis of Arabidopsis thaliana mature stems.

    PubMed

    Duruflé, Harold; Clemente, Hélène San; Balliau, Thierry; Zivy, Michel; Dunand, Christophe; Jamet, Elisabeth

    2017-04-01

    Plant stems carry flowers necessary for species propagation and need to be adapted to mechanical disturbance and environmental factors. The stem cell walls are different from other organs and can modify their rigidity or viscoelastic properties for the integrity and the robustness required to withstand mechanical impacts and environmental stresses. Plant cell wall is composed of complex polysaccharide networks also containing cell wall proteins (CWPs) crucial to perceive and limit the environmental effects. The CWPs are fundamental players in cell wall remodeling processes, and today, only 86 have been identified from the mature stems of the model plant Arabidopsis thaliana. With a destructive method, this study has enlarged its coverage to 302 CWPs. This new proteome is mainly composed of 27.5% proteins acting on polysaccharides, 16% proteases, 11.6% oxido-reductases, 11% possibly related to lipid metabolism and 11% of proteins with interacting domains with proteins or polysaccharides. Compared to stem cell wall proteomes already available (Brachypodium distachyon, Sacharum officinarum, Linum usitatissimum, Medicago sativa), that of A. thaliana stems has a higher proportion of proteins acting on polysaccharides and of proteases, but a lower proportion of oxido-reductases. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. (+)-Thalianatriene and (-)-Retigeranin B Catalyzed by Sesterterpene Synthases from Arabidopsis thaliana.

    PubMed

    Shao, Jie; Chen, Qing-Wen; Lv, Hua-Jun; He, Juan; Liu, Zhi-Feng; Lu, Yan-Na; Liu, Hai-Li; Wang, Guo-Dong; Wang, Yong

    2017-04-07

    Two GFPPS linked (+)-thalianatriene (1) and (-)-retigeranin B (2) sesterterpene synthase genes were identified from the genome of Arabidopsis thaliana. 1 possesses an unprecedented 11-6-5 tricyclic ring system, while 2 contains a characteristic 5-5-5-6-5 pentacyclic ring system. Their structures were determined by extensive NMR spectroscopy, chemical derivatization, and X-ray crystallography. The variable-temp NMR measurement of 3, a diepoxy-bearing derivative of 1, enables us to completely assign the NMR signals of the two conformers as 3a (67%, UUU) and 3b (33%, UUD). A plausible biosynthesis mechanism of 1 was proposed.

  16. Diverse accumulation of several dehydrin-like proteins in cauliflower (Brassica oleracea var. botrytis), Arabidopsis thaliana and yellow lupin (Lupinus luteus) mitochondria under cold and heat stress.

    PubMed

    Rurek, Michal

    2010-08-18

    Dehydrins represent hydrophilic proteins acting mainly during cell dehydration and stress response. Dehydrins are generally thermostable; however, the so-called dehydrin-like (dehydrin-related) proteins show variable thermolability. Both groups immunoreact with antibodies directed against the K-segment of dehydrins. Plant mitochondrial dehydrin-like proteins are poorly characterized. The purpose of this study was to extend previous reports on plant dehydrins by comparing the level of immunoprecipitated dehydrin-like proteins in cauliflower (Brassica oleracea var. botrytis), Arabidopsis thaliana and yellow lupin (Lupinus luteus) mitochondria under cold and heat stress. All the analyzed plant species showed constitutive accumulation of thermostable mitochondrial putative dehydrins ranging from 50 to 70 kDa. The mitochondrial dehydrin-like proteins observed in cauliflower and Arabidopsis ranged from 10 to 100 kDa and in lupin imbibed seeds and hypocotyls--from 20 to 90 kDa. Cold treatment increased mainly the accumulation of 10-100 kDa cauliflower and Arabidopsis dehydrin-like proteins, in the patterns different in cauliflower leaf and inflorescence mitochondria. However, in lupin mitochondria, cold affected mainly 25-50 kDa proteins and seemed to induce the appearance of some novel dehydrin-like proteins. The influence of frost stress on cauliflower leaf mitochondrial dehydrin- like proteins was less significant. The impact of heat stress was less significant in lupin and Arabidopsis than in cauliflower inflorescence mitochondria. Cauliflower mitochondrial dehydrin-like proteins are localized mostly in the mitochondrial matrix; it seems that some of them may interact with mitochondrial membranes. All the results reveal an unexpectedly broad spectrum of dehydrin-like proteins accumulated during some abiotic stress in the mitochondria of the plant species analyzed. They display only limited similarity in size to those reported previously in maize, wheat and rye

  17. Biochemical quantitation of the eIF5A hypusination in Arabidopsis thaliana uncovers ABA-dependent regulation

    PubMed Central

    Belda-Palazón, Borja; Nohales, María A.; Rambla, José L.; Aceña, José L.; Delgado, Oscar; Fustero, Santos; Martínez, M. Carmen; Granell, Antonio; Carbonell, Juan; Ferrando, Alejandro

    2014-01-01

    The eukaryotic translation elongation factor eIF5A is the only protein known to contain the unusual amino acid hypusine which is essential for its biological activity. This post-translational modification is achieved by the sequential action of the enzymes deoxyhypusine synthase (DHS) and deoxyhypusine hydroxylase (DOHH). The crucial molecular function of eIF5A during translation has been recently elucidated in yeast and it is expected to be fully conserved in every eukaryotic cell, however the functional description of this pathway in plants is still sparse. The genetic approaches with transgenic plants for either eIF5A overexpression or antisense have revealed some activities related to the control of cell death processes but the molecular details remain to be characterized. One important aspect of fully understanding this pathway is the biochemical description of the hypusine modification system. Here we have used recombinant eIF5A proteins either modified by hypusination or non-modified to establish a bi-dimensional electrophoresis (2D-E) profile for the three eIF5A protein isoforms and their hypusinated or unmodified proteoforms present in Arabidopsis thaliana. The combined use of the recombinant 2D-E profile together with 2D-E/western blot analysis from whole plant extracts has provided a quantitative approach to measure the hypusination status of eIF5A. We have used this information to demonstrate that treatment with the hormone abscisic acid produces an alteration of the hypusine modification system in Arabidopsis thaliana. Overall this study presents the first biochemical description of the post-translational modification of eIF5A by hypusination which will be functionally relevant for future studies related to the characterization of this pathway in Arabidopsis thaliana. PMID:24904603

  18. BRUTUS and its paralogs, BTS LIKE1 and BTS LIKE2, encode important negative regulators of the iron deficiency response in Arabidopsis thaliana

    USDA-ARS?s Scientific Manuscript database

    Iron (Fe) is required for plant health, but it can also be toxic when present in excess. Therefore, Fe levels must be tightly controlled. The Arabidopsis thaliana E3 ligase BRUTUS (BTS) is involved in the negative regulation of the Fe deficiency response and we show here that the two A. thaliana BTS...

  19. Long noncoding RNAs responsive to Fusarium oxysporum infection in Arabidopsis thaliana.

    PubMed

    Zhu, Qian-Hao; Stephen, Stuart; Taylor, Jennifer; Helliwell, Chris A; Wang, Ming-Bo

    2014-01-01

    Short noncoding RNAs have been demonstrated to play important roles in regulation of gene expression and stress responses, but the repertoire and functions of long noncoding RNAs (lncRNAs) remain largely unexplored, particularly in plants. To explore the role of lncRNAs in disease resistance, we used a strand-specific RNA-sequencing approach to identify lncRNAs responsive to Fusarium oxysporum infection in Arabidopsis thaliana. Antisense transcription was found in c. 20% of the annotated A. thaliana genes. Several noncoding natural antisense transcripts responsive to F. oxysporum infection were found in genes implicated in disease defense. While the majority of the novel transcriptionally active regions (TARs) were adjacent to annotated genes and could be an extension of the annotated transcripts, 159 novel intergenic TARs, including 20 F. oxysporum-responsive lncTARs, were identified. Ten F. oxysporum-induced lncTARs were functionally characterized using T-DNA insertion or RNA-interference knockdown lines, and five were demonstrated to be related to disease development. Promoter analysis suggests that some of the F. oxysporum-induced lncTARs are direct targets of transcription factor(s) responsive to pathogen attack. Our results demonstrated that strand-specific RNA sequencing is a powerful tool for uncovering hidden levels of transcriptome and that IncRNAs are important components of the antifungal networks in A. thaliana. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  20. Reproductive, morphological, and phytochemical responses of Arabidopsis thaliana ecotypes to enhanced UV-B radiation

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

    Trumbull, V.L.; McCloud, E.S.; Paige, K.N.

    1994-06-01

    Two ecotypes of Arabidopsis thaliana, collected from Libya and Norway, were grown in the greenhouse under. UV-B doses of 0 and 10.5 kJ m[sup [minus]2] UV-B[sub BE]. The high UV-B dose simulated midsummer ambient conditions over Libya and a 40% reduction in stratospheric ozone over Norway. The Libyan ectotype, which originated from latitudes where solar UV-B is high, showed no UV-B induced damage to plant growth. However the Norwegian ecotype, which originated from latitudes where solar UV-B is low, showed a significant reduction in plant height, inflorescence weight, and rosette weight in response to enhanced UV-B. Although fruit and seedmore » number for both ecotypes were unaffected by enhanced UV-B radiation the germination success of the seeds harvested from the irradiated Norwegian plants were significantly reduced. The two ecotypes also differed with respect to their accumulation of kaempferol, a putative UV-B protective filter. The Libyan ecotype increased kaempferol concentration by 38% over the 0 kJ treatment whereas the Norwegian ecotype increased by only 15%. These data suggest that, for these ecotypes, variation in UV-B sensitivity may be explained by the differential induction of UV-absorbing leaf pigments.« less

  1. Analysis and visualization of Arabidopsis thaliana GWAS using web 2.0 technologies.

    PubMed

    Huang, Yu S; Horton, Matthew; Vilhjálmsson, Bjarni J; Seren, Umit; Meng, Dazhe; Meyer, Christopher; Ali Amer, Muhammad; Borevitz, Justin O; Bergelson, Joy; Nordborg, Magnus

    2011-01-01

    With large-scale genomic data becoming the norm in biological studies, the storing, integrating, viewing and searching of such data have become a major challenge. In this article, we describe the development of an Arabidopsis thaliana database that hosts the geographic information and genetic polymorphism data for over 6000 accessions and genome-wide association study (GWAS) results for 107 phenotypes representing the largest collection of Arabidopsis polymorphism data and GWAS results to date. Taking advantage of a series of the latest web 2.0 technologies, such as Ajax (Asynchronous JavaScript and XML), GWT (Google-Web-Toolkit), MVC (Model-View-Controller) web framework and Object Relationship Mapper, we have created a web-based application (web app) for the database, that offers an integrated and dynamic view of geographic information, genetic polymorphism and GWAS results. Essential search functionalities are incorporated into the web app to aid reverse genetics research. The database and its web app have proven to be a valuable resource to the Arabidopsis community. The whole framework serves as an example of how biological data, especially GWAS, can be presented and accessed through the web. In the end, we illustrate the potential to gain new insights through the web app by two examples, showcasing how it can be used to facilitate forward and reverse genetics research. Database URL: http://arabidopsis.usc.edu/

  2. Changes in Arabidopsis leaf ultrastructure, chlorophyll and carbohydrate content during spaceflight depend on ventilation

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    Leaf structure and function under spaceflight conditions have received little study despite their important implications for biological life support systems using plants. Previous reports described disruption of the membrane apparatus for photosynthesis and a general decrease in carbohydrate content in foliage. During a series of three short-duration experiments (Chromex-03, -04, -05) on the US space shuttle (STS-54, STS-51, STS-68), we examined Arabidopsis thaliana leaves. The plants were at the rosette stage at the time of loading onto the space shuttle, and received the same light, temperature, carbon dioxide and humidity regimes in the orbiter as in ground controls. The experiments differed according to the regime provided in the headspace around the plants: this was either sealed (on mission STS-54); sealed with high levels of carbon dioxide (on mission STS-51) or vented to the cabin air through a filtration system (on mission STS-68). Immediately post-flight, leaf materials were fixed for microscopy or frozen in liquid nitrogen for subsequent analyses of chlorophyll and foliar carbohydrates. At the ultrastructural level, no aberrations in membrane structure were observed in any of the experiments. When air-flow was provided, plastids developed large starch grains in both spaceflight and ground controls. In the experiments with sealed chambers, spaceflight plants differed from ground controls with regard to measured concentrations of carbohydrate and chlorophyll, but the addition of airflow eliminated these differences. The results point to the crucial importance of consideration of the foliage microenvironment when spaceflight effects on leaf structure and metabolism are studied.

  3. Structure of Arabidopsis thaliana Rubisco activase.

    PubMed

    Hasse, Dirk; Larsson, Anna M; Andersson, Inger

    2015-04-01

    The CO2-fixing enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is inactivated by the formation of dead-end complexes with inhibitory sugar phosphates. In plants and green algae, the ATP-dependent motor protein Rubisco activase restores catalytic competence by facilitating conformational changes in Rubisco that promote the release of the inhibitory compounds from the active site. Here, the crystal structure of Rubisco activase from Arabidopsis thaliana is presented at 2.9 Å resolution. The structure reveals an AAA+ two-domain structure. More than 100 residues in the protein were not visible in the electron-density map owing to conformational disorder, but were verified to be present in the crystal by mass spectrometry. Two sulfate ions were found in the structure. One was bound in the loop formed by the Walker A motif at the interface of the domains. A second sulfate ion was bound at the N-terminal end of the first helix of the C-terminal domain. The protein packs in a helical fashion in the crystal, as observed previously for Rubisco activase, but differences in the helical pitch indicate flexibility in the packing of the protein.

  4. Cell-specific vacuolar calcium storage mediated by "CAX1" regulates apoplastic calcium concentration, gas exchange, and plant productivity in "Arabidopsis"

    USDA-ARS?s Scientific Manuscript database

    The physiological role and mechanism of nutrient storage within vacuoles of specific cell types is poorly understood. Transcript profiles from "Arabidopsis thaliana" leaf cells differing in calcium concentration ([Ca], epidermis <10 mM versus mesophyll >60 mM) were compared using a microarray screen...

  5. TORNADO1 regulates root epidermal patterning through the WEREWOLF pathway in Arabidopsis thaliana.

    PubMed

    Kwak, Su-Hwan; Song, Sang-Kee; Lee, Myeong Min; Schiefelbein, John

    2015-01-01

    Cell fate in the root epidermis of Arabidopsis thaliana is determined in a position-dependent manner. SCRAMBLED (SCM), an atypical leucine-rich repeat receptor-like kinase, mediates this positional regulation via its effect on WEREWOLF (WER) expression, and subsequently, its downstream transcription factor, GLABRA2 (GL2), which are required for nonhair cell development. Previously, TORNADO1 (TRN1), a plant-specific protein with a leucine-rich repeat ribonuclease inhibitor-like domain, was shown to be required for proper epidermal patterning in Arabidopsis roots. In this work, we analyzed the possible involvement of TRN1 in the known root epidermal gene network. We discovered that the trn1 mutant caused the ectopic expression of WER and the randomized expression of GL2 and EGL3. This suggests that TRN1 regulates the position-dependent cell fate determination by affecting WER expression in Arabidopsis root epidermis. Additionally, the distinct phenotypes of the aerial parts of the trn1-t and scm-2 mutant suggest that TRN1 and SCM might have different functions in the development of aerial parts.

  6. TORNADO1 regulates root epidermal patterning through the WEREWOLF pathway in Arabidopsis thaliana

    PubMed Central

    Kwak, Su-Hwan; Song, Sang-Kee; Lee, Myeong Min; Schiefelbein, John

    2015-01-01

    Cell fate in the root epidermis of Arabidopsis thaliana is determined in a position-dependent manner. SCRAMBLED (SCM), an atypical leucine-rich repeat receptor-like kinase, mediates this positional regulation via its effect on WEREWOLF (WER) expression, and subsequently, its downstream transcription factor, GLABRA2 (GL2), which are required for nonhair cell development. Previously, TORNADO1 (TRN1), a plant-specific protein with a leucine-rich repeat ribonuclease inhibitor-like domain, was shown to be required for proper epidermal patterning in Arabidopsis roots. In this work, we analyzed the possible involvement of TRN1 in the known root epidermal gene network. We discovered that the trn1 mutant caused the ectopic expression of WER and the randomized expression of GL2 and EGL3. This suggests that TRN1 regulates the position-dependent cell fate determination by affecting WER expression in Arabidopsis root epidermis. Additionally, the distinct phenotypes of the aerial parts of the trn1-t and scm-2 mutant suggest that TRN1 and SCM might have different functions in the development of aerial parts. PMID:26451798

  7. 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

  8. Cell wall accumulation of fluorescent proteins derived from a trans-Golgi cisternal membrane marker and paramural bodies in interdigitated Arabidopsis leaf epidermal cells.

    PubMed

    Akita, Kae; Kobayashi, Megumi; Sato, Mayuko; Kutsuna, Natsumaro; Ueda, Takashi; Toyooka, Kiminori; Nagata, Noriko; Hasezawa, Seiichiro; Higaki, Takumi

    2017-01-01

    In most dicotyledonous plants, leaf epidermal pavement cells develop jigsaw puzzle-like shapes during cell expansion. The rapid growth and complicated cell shape of pavement cells is suggested to be achieved by targeted exocytosis that is coordinated with cytoskeletal rearrangement to provide plasma membrane and/or cell wall materials for lobe development during their morphogenesis. Therefore, visualization of membrane trafficking in leaf pavement cells should contribute an understanding of the mechanism of plant cell morphogenesis. To reveal membrane trafficking in pavement cells, we observed monomeric red fluorescent protein-tagged rat sialyl transferases, which are markers of trans-Golgi cisternal membranes, in the leaf epidermis of Arabidopsis thaliana. Quantitative fluorescence imaging techniques and immunoelectron microscopic observations revealed that accumulation of the red fluorescent protein occurred mostly in the curved regions of pavement cell borders and guard cell ends during leaf expansion. Transmission electron microscopy observations revealed that apoplastic vesicular membrane structures called paramural bodies were more frequent beneath the curved cell wall regions of interdigitated pavement cells and guard cell ends in young leaf epidermis. In addition, pharmacological studies showed that perturbations in membrane trafficking resulted in simple cell shapes. These results suggested possible heterogeneity of the curved regions of plasma membranes, implying a relationship with pavement cell morphogenesis.

  9. Growth distribution during phototropism of Arabidopsis thaliana seedlings

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

    Orbovic, V.; Poff, K.L.

    1993-09-01

    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 themore » 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. 31 refs., 7 figs.« less

  10. Spatio-temporal variation in fitness responses to contrasting environments in Arabidopsis thaliana.

    PubMed

    Exposito-Alonso, Moises; Brennan, Adrian C; Alonso-Blanco, Carlos; Picó, F Xavier

    2018-06-27

    The evolutionary response of organisms to global climate change is expected to be strongly conditioned by preexisting standing genetic variation. In addition, natural selection imposed by global climate change on fitness-related traits can be heterogeneous over time. We estimated selection of life-history traits of an entire genetic lineage of the plant Arabidopsis thaliana occurring in north-western Iberian Peninsula that were transplanted over multiple years into two environmentally contrasting field sites in southern Spain, as southern environments are expected to move progressively northwards with climate change in the Iberian Peninsula. The results indicated that natural selection on flowering time prevailed over that on recruitment. Selection favored early flowering in six of eight experiments and late flowering in the other two. Such heterogeneity of selection for flowering time might be a powerful mechanism for maintaining genetic diversity in the long run. We also found that north-western A. thaliana accessions from warmer environments exhibited higher fitness and higher phenotypic plasticity for flowering time in southern experimental facilities. Overall, our transplant experiments suggested that north-western Iberian A. thaliana has the means to cope with increasingly warmer environments in the region as predicted by trends in global climate change models. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

  11. Overexpression of Arabidopsis thaliana brassinosteroid-related acyltransferase 1 gene induces brassinosteroid-deficient phenotypes in creeping bentgrass

    PubMed Central

    Han, Yun-Jeong; Kim, Young Soon; Hwang, Ok-Jin; Roh, Jeehee; Ganguly, Keya; Kim, Seong-Ki; Hwang, Ildoo

    2017-01-01

    Brassinosteroids (BRs) are naturally occurring steroidal hormones that play diverse roles in various processes during plant growth and development. Thus, genetic manipulation of endogenous BR levels might offer a way of improving the agronomic traits of crops, including plant architecture and stress tolerance. In this study, we produced transgenic creeping bentgrass (Agrostis stolonifera L.) overexpressing a BR-inactivating enzyme, Arabidopsis thaliana BR-related acyltransferase 1 (AtBAT1), which is known to catalyze the conversion of BR intermediates to inactive acylated conjugates. After putative transgenic plants were selected using herbicide resistance assay, genomic integration of the AtBAT1 gene was confirmed by genomic PCR and Southern blot analysis, and transgene expression was validated by northern blot analysis. The transgenic creeping bentgrass plants exhibited BR-deficient phenotypes, including reduced plant height with shortened internodes (i.e., semi-dwarf), reduced leaf growth rates with short, wide, and thick architecture, high chlorophyll contents, decreased numbers of vascular bundles, and large lamina joint bending angles (i.e., erect leaves). Subsequent analyses showed that the transgenic plants had significantly reduced amounts of endogenous BR intermediates, including typhasterol, 6-deoxocastasterone, and castasterone. Moreover, the AtBAT1 transgenic plants displayed drought tolerance as well as delayed senescence. Therefore, the results of the present study demonstrate that overexpression of an Arabidopsis BR-inactivating enzyme can reduce the endogenous levels of BRs in creeping bentgrass resulting in BR-deficient phenotypes, indicating that the AtBAT1 gene from a dicot plant is also functional in the monocot crop. PMID:29084267

  12. Variation of 45S rDNA intergenic spacers in Arabidopsis thaliana.

    PubMed

    Havlová, Kateřina; Dvořáčková, Martina; Peiro, Ramon; Abia, David; Mozgová, Iva; Vansáčová, Lenka; Gutierrez, Crisanto; Fajkus, Jiří

    2016-11-01

    Approximately seven hundred 45S rRNA genes (rDNA) in the Arabidopsis thaliana genome are organised in two 4 Mbp-long arrays of tandem repeats arranged in head-to-tail fashion separated by an intergenic spacer (IGS). These arrays make up 5 % of the A. thaliana genome. IGS are rapidly evolving sequences and frequent rearrangements inside the rDNA loci have generated considerable interspecific and even intra-individual variability which allows to distinguish among otherwise highly conserved rRNA genes. The IGS has not been comprehensively described despite its potential importance in regulation of rDNA transcription and replication. Here we describe the detailed sequence variation in the complete IGS of A. thaliana WT plants and provide the reference/consensus IGS sequence, as well as genomic DNA analysis. We further investigate mutants dysfunctional in chromatin assembly factor-1 (CAF-1) (fas1 and fas2 mutants), which are known to have a reduced number of rDNA copies, and plant lines with restored CAF-1 function (segregated from a fas1xfas2 genetic background) showing major rDNA rearrangements. The systematic rDNA loss in CAF-1 mutants leads to the decreased variability of the IGS and to the occurrence of distinct IGS variants. We present for the first time a comprehensive and representative set of complete IGS sequences, obtained by conventional cloning and by Pacific Biosciences sequencing. Our data expands the knowledge of the A. thaliana IGS sequence arrangement and variability, which has not been available in full and in detail until now. This is also the first study combining IGS sequencing data with RFLP analysis of genomic DNA.

  13. Photoassimilation, Assimilate Translocation and Plasmodesmal Biogenesis in the Source Leaves of Arabidopsis thaliana Grown Under an Increased Atmospheric CO2 Concentration

    PubMed Central

    Duan, Zhongrui; Homma, Ayumi; Kobayashi, Megumi; Nagata, Noriko; Kaneko, Yasuko; Fujiki, Yuki; Nishida, Ikuo

    2014-01-01

    Using 18-day-old Arabidopsis thaliana seedlings grown under increased (780 p.p.m., experimental plants) or ambient (390 p.p.m., control plants) CO2 conditions, we evaluated 14CO2 photoassimilation in and translocation from representative source leaves. The total 14CO2 photoassimilation amounts increased in the third leaves of the experimental plants in comparison with that found for the third leaves of the control plants, but the rates were comparable for the first leaves of the two groups. In contrast, translocation of labeled assimilates doubled in the first leaves of the experimental group, whereas translocation was, at best, passively enhanced even though photoassimilation increased in their third leaves. The transcript levels of the companion cell-specific sucrose:H+ symporter gene SUC2 were not significantly affected in the two groups of plants, whereas those of the sucrose effluxer gene SWEET12 and the sieve element-targeted sucrose:H+ symporter gene SUT4 were up-regulated in the experimental plants, suggesting up-regulation of SUT4-dependent apoplastic phloem loading. Compared with SUC2, SUT4 is a minor component that is expressed in companion cells but functions in sieve elements after transfer through plasmodesmata. The number of aniline blue-stained spots for plasmodesma-associated callose in the midrib wall increased in the first leaf of the experimental plants but was comparable in the third leaf between the experimental and control plants. These results suggest that A. thaliana responds to greater than normal concentrations of CO2 differentially in the first and third leaves in regards to photoassimilation, assimilate translocation and plasmodesmal biogenesis. PMID:24406629

  14. Cadmium-induced ethylene production and responses in Arabidopsis thaliana rely on ACS2 and ACS6 gene expression

    PubMed Central

    2014-01-01

    Background Anthropogenic activities cause metal pollution worldwide. Plants can absorb and accumulate these metals through their root system, inducing stress as a result of excess metal concentrations inside the plant. Ethylene is a regulator of multiple plant processes, and is affected by many biotic and abiotic stresses. Increased ethylene levels have been observed after exposure to excess metals but it remains unclear how the increased ethylene levels are achieved at the molecular level. In this study, the effects of cadmium (Cd) exposure on the production of ethylene and its precursor 1-aminocyclopropane-1-carboxylic acid (ACC), and on the expression of the ACC Synthase (ACS) and ACC Oxidase (ACO) multigene families were investigated in Arabidopsis thaliana. Results Increased ethylene release after Cd exposure was directly measurable in a system using rockwool-cultivated plants; enhanced levels of the ethylene precursor ACC together with higher mRNA levels of ethylene responsive genes: ACO2, ETR2 and ERF1 also indicated increased ethylene production in hydroponic culture. Regarding underlying mechanisms, it was found that the transcript levels of ACO2 and ACO4, the most abundantly expressed members of the ACO multigene family, were increased upon Cd exposure. ACC synthesis is the rate-limiting step in ethylene biosynthesis, and transcript levels of both ACS2 and ACS6 showed the highest increase and became the most abundant isoforms after Cd exposure, suggesting their importance in the Cd-induced increase of ethylene production. Conclusions Cadmium induced the biosynthesis of ACC and ethylene in Arabidopsis thaliana plants mainly via the increased expression of ACS2 and ACS6. This was confirmed in the acs2-1acs6-1 double knockout mutants, which showed a decreased ethylene production, positively affecting leaf biomass and resulting in a delayed induction of ethylene responsive gene expressions without significant differences in Cd contents between wild-type and

  15. Transcriptional and metabolomic analysis of Ascophyllum nodosum mediated freezing tolerance in Arabidopsis thaliana

    PubMed Central

    2012-01-01

    Background We have previously shown that lipophilic components (LPC) of the brown seaweed Ascophyllum nodosum (ANE) improved freezing tolerance in Arabidopsis thaliana. However, the mechanism(s) of this induced freezing stress tolerance is largely unknown. Here, we investigated LPC induced changes in the transcriptome and metabolome of A. thaliana undergoing freezing stress. Results Gene expression studies revealed that the accumulation of proline was mediated by an increase in the expression of the proline synthesis genes P5CS1 and P5CS2 and a marginal reduction in the expression of the proline dehydrogenase (ProDH) gene. Moreover, LPC application significantly increased the concentration of total soluble sugars in the cytosol in response to freezing stress. Arabidopsis sfr4 mutant plants, defective in the accumulation of free sugars, treated with LPC, exhibited freezing sensitivity similar to that of untreated controls. The 1H NMR metabolite profile of LPC-treated Arabidopsis plants exposed to freezing stress revealed a spectrum dominated by chemical shifts (δ) representing soluble sugars, sugar alcohols, organic acids and lipophilic components like fatty acids, as compared to control plants. Additionally, 2D NMR spectra suggested an increase in the degree of unsaturation of fatty acids in LPC treated plants under freezing stress. These results were supported by global transcriptome analysis. Transcriptome analysis revealed that LPC treatment altered the expression of 1113 genes (5%) in comparison with untreated plants. A total of 463 genes (2%) were up regulated while 650 genes (3%) were down regulated. Conclusion Taken together, the results of the experiments presented in this paper provide evidence to support LPC mediated freezing tolerance enhancement through a combination of the priming of plants for the increased accumulation of osmoprotectants and alteration of cellular fatty acid composition. PMID:23171218

  16. Effects of mutations in the Arabidopsis Cold Shock Domain Protein 3 (AtCSP3) gene on leaf cell expansion.

    PubMed

    Yang, Yongil; Karlson, Dale

    2012-08-01

    The cold shock domain is among the most evolutionarily conserved nucleic acid binding domains from prokaryotes to higher eukaryotes, including plants. Although eukaryotic cold shock domain proteins have been extensively studied as transcriptional and post-transcriptional regulators during various developmental processes, their functional roles in plants remains poorly understood. In this study, AtCSP3 (At2g17870), which is one of four Arabidopsis thaliana c old s hock domain proteins (AtCSPs), was functionally characterized. Quantitative RT-PCR analysis confirmed high expression of AtCSP3 in reproductive and meristematic tissues. A homozygous atcsp3 loss-of-function mutant exhibits an overall reduced seedling size, stunted and orbicular rosette leaves, reduced petiole length, and curled leaf blades. Palisade mesophyll cells are smaller and more circular in atcsp3 leaves. Cell size analysis indicated that the reduced size of the circular mesophyll cells appears to be generated by a reduction of cell length along the leaf-length axis, resulting in an orbicular leaf shape. It was also determined that leaf cell expansion is impaired for lateral leaf development in the atcsp3 loss-of-function mutant, but leaf cell proliferation is not affected. AtCSP3 loss-of-function resulted in a dramatic reduction of LNG1 transcript, a gene that is involved in two-dimensional leaf polarity regulation. Transient subcellular localization of AtCSP3 in onion epidermal cells confirmed a nucleocytoplasmic localization pattern. Collectively, these data suggest that AtCSP3 is functionally linked to the regulation of leaf length by affecting LNG1 transcript accumulation during leaf development. A putative function of AtCSP3 as an RNA binding protein is also discussed in relation to leaf development.

  17. The Starch Granule-Associated Protein EARLY STARVATION1 Is Required for the Control of Starch Degradation in Arabidopsis thaliana Leaves[OPEN

    PubMed Central

    Feike, Doreen; Seung, David; Graf, Alexander; Bischof, Sylvain; Ellick, Tamaryn; Coiro, Mario; Soyk, Sebastian; Eicke, Simona; Mettler-Altmann, Tabea; Lu, Kuan Jen; Trick, Martin; Zeeman, Samuel C.

    2016-01-01

    To uncover components of the mechanism that adjusts the rate of leaf starch degradation to the length of the night, we devised a screen for mutant Arabidopsis thaliana plants in which starch reserves are prematurely exhausted. The mutation in one such mutant, named early starvation1 (esv1), eliminates a previously uncharacterized protein. Starch in mutant leaves is degraded rapidly and in a nonlinear fashion, so that reserves are exhausted 2 h prior to dawn. The ESV1 protein and a similar uncharacterized Arabidopsis protein (named Like ESV1 [LESV]) are located in the chloroplast stroma and are also bound into starch granules. The region of highest similarity between the two proteins contains a series of near-repeated motifs rich in tryptophan. Both proteins are conserved throughout starch-synthesizing organisms, from angiosperms and monocots to green algae. Analysis of transgenic plants lacking or overexpressing ESV1 or LESV, and of double mutants lacking ESV1 and another protein necessary for starch degradation, leads us to propose that these proteins function in the organization of the starch granule matrix. We argue that their misexpression affects starch degradation indirectly, by altering matrix organization and, thus, accessibility of starch polymers to starch-degrading enzymes. PMID:27207856

  18. Positive regulatory role of sound vibration treatment in Arabidopsis thaliana against Botrytis cinerea infection.

    PubMed

    Choi, Bosung; Ghosh, Ritesh; Gururani, Mayank Anand; Shanmugam, Gnanendra; Jeon, Junhyun; Kim, Jonggeun; Park, Soo-Chul; Jeong, Mi-Jeong; Han, Kyung-Hwan; Bae, Dong-Won; Bae, Hanhong

    2017-05-30

    Sound vibration (SV), a mechanical stimulus, can trigger various molecular and physiological changes in plants like gene expression, hormonal modulation, induced antioxidant activity and calcium spiking. It also alters the seed germination and growth of plants. In this study, we investigated the effects of SV on the resistance of Arabidopsis thaliana against Botrytis cinerea infection. The microarray analysis was performed on infected Arabidopsis plants pre-exposed to SV of 1000 Hertz with 100 decibels. Broadly, the transcriptomic analysis revealed up-regulation of several defense and SA-responsive and/or signaling genes. Quantitative real-time PCR (qRT-PCR) analysis of selected genes also validated the induction of SA-mediated response in the infected Arabidopsis plants pre-exposed to SV. Corroboratively, hormonal analysis identified the increased concentration of salicylic acid (SA) in the SV-treated plants after pathogen inoculation. In contrast, jasmonic acid (JA) level in the SV-treated plants remained stable but lower than control plants during the infection. Based on these findings, we propose that SV treatment invigorates the plant defense system by regulating the SA-mediated priming effect, consequently promoting the SV-induced resistance in Arabidopsis against B. cinerea.

  19. Chemical inhibition of a subset of Arabidopsis thaliana GSK3-like kinases activates brassinosteroid signaling.

    PubMed

    De Rybel, Bert; Audenaert, Dominique; Vert, Grégory; Rozhon, Wilfried; Mayerhofer, Juliane; Peelman, Frank; Coutuer, Silvie; Denayer, Tinneke; Jansen, Leentje; Nguyen, Long; Vanhoutte, Isabelle; Beemster, Gerrit T S; Vleminckx, Kris; Jonak, Claudia; Chory, Joanne; Inzé, Dirk; Russinova, Eugenia; Beeckman, Tom

    2009-06-26

    Glycogen synthase kinase 3 (GSK3) is a key regulator in signaling pathways in both animals and plants. Three Arabidopsis thaliana GSK3s are shown to be related to brassinosteroid (BR) signaling. In a phenotype-based compound screen we identified bikinin, a small molecule that activates BR signaling downstream of the BR receptor. Bikinin directly binds the GSK3 BIN2 and acts as an ATP competitor. Furthermore, bikinin inhibits the activity of six other Arabidopsis GSK3s. Genome-wide transcript analyses demonstrate that simultaneous inhibition of seven GSK3s is sufficient to activate BR responses. Our data suggest that GSK3 inhibition is the sole activation mode of BR signaling and argues against GSK3-independent BR responses in Arabidopsis. The opportunity to generate multiple and conditional knockouts in key regulators in the BR signaling pathway by bikinin represents a useful tool to further unravel regulatory mechanisms.

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

    PubMed

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

    2004-05-18

    DNA gyrase is the bacterial DNA topoisomerase (topo) that supercoils DNA by using the free energy of ATP hydrolysis. The enzyme, an A(2)B(2) 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.

  1. Elemental concentrations in the seed of mutants and natural variants of Arabidopsis thaliana grown under varying soil conditions

    USDA-ARS?s Scientific Manuscript database

    The concentrations of mineral nutrients in seeds are critical to both the life cycle of plants as well as human nutrition. These concentrations are strongly influenced by soil conditions, as shown here by quantifying the concentration of 14 elements in seeds from Arabidopsis thaliana plants grown un...

  2. Model-Based Analysis of Arabidopsis Leaf Epidermal Cells Reveals Distinct Division and Expansion Patterns for Pavement and Guard Cells1[W][OA

    PubMed Central

    Asl, Leila Kheibarshekan; Dhondt, Stijn; Boudolf, Véronique; Beemster, Gerrit T.S.; Beeckman, Tom; Inzé, Dirk; Govaerts, Willy; De Veylder, Lieven

    2011-01-01

    To efficiently capture sunlight for photosynthesis, leaves typically develop into a flat and thin structure. This development is driven by cell division and expansion, but the individual contribution of these processes is currently unknown, mainly because of the experimental difficulties to disentangle them in a developing organ, due to their tight interconnection. To circumvent this problem, we built a mathematic model that describes the possible division patterns and expansion rates for individual epidermal cells. This model was used to fit experimental data on cell numbers and sizes obtained over time intervals of 1 d throughout the development of the first leaf pair of Arabidopsis (Arabidopsis thaliana). The parameters were obtained by a derivative-free optimization method that minimizes the differences between the predicted and experimentally observed cell size distributions. The model allowed us to calculate probabilities for a cell to divide into guard or pavement cells, the maximum size at which it can divide, and its average cell division and expansion rates at each point during the leaf developmental process. Surprisingly, average cell cycle duration remained constant throughout leaf development, whereas no evidence for a maximum cell size threshold for cell division of pavement cells was found. Furthermore, the model predicted that neighboring cells of different sizes within the epidermis expand at distinctly different relative rates, which could be verified by direct observations. We conclude that cell division seems to occur independently from the status of cell expansion, whereas the cell cycle might act as a timer rather than as a size-regulated machinery. PMID:21693673

  3. Genome Wide Association Mapping in Arabidopsis thaliana Identifies Novel Genes Involved in Linking Allyl Glucosinolate to Altered Biomass and Defense.

    PubMed

    Francisco, Marta; Joseph, Bindu; Caligagan, Hart; Li, Baohua; Corwin, Jason A; Lin, Catherine; Kerwin, Rachel E; Burow, Meike; Kliebenstein, Daniel J

    2016-01-01

    A key limitation in modern biology is the ability to rapidly identify genes underlying newly identified complex phenotypes. Genome wide association studies (GWAS) have become an increasingly important approach for dissecting natural variation by associating phenotypes with genotypes at a genome wide level. Recent work is showing that the Arabidopsis thaliana defense metabolite, allyl glucosinolate (GSL), may provide direct feedback regulation, linking defense metabolism outputs to the growth, and defense responses of the plant. However, there is still a need to identify genes that underlie this process. To start developing a deeper understanding of the mechanism(s) that modulate the ability of exogenous allyl GSL to alter growth and defense, we measured changes in plant biomass and defense metabolites in a collection of natural 96 A. thaliana accessions fed with 50 μM of allyl GSL. Exogenous allyl GSL was introduced exclusively to the roots and the compound transported to the leaf leading to a wide range of heritable effects upon plant biomass and endogenous GSL accumulation. Using natural variation we conducted GWAS to identify a number of new genes which potentially control allyl responses in various plant processes. This is one of the first instances in which this approach has been successfully utilized to begin dissecting a novel phenotype to the underlying molecular/polygenic basis.

  4. Deficiency of adenosine kinase activity affects the degree of pectin methyl-esterification in cell walls of Arabidopsis thaliana.

    PubMed

    Pereira, L A R; Schoor, S; Goubet, F; Dupree, P; Moffatt, B A

    2006-11-01

    Pectin methyl-esterification is catalysed by S-adenosyl-L: -methionine (SAM)-dependent methyltransferases. As deficiency in adenosine kinase (ADK; EC 2.7.1.20) activity impairs SAM recycling and utilization, we investigated the relationship between ADK-deficiency and the degree of pectin methyl-esterification in cell walls of Arabidopsis thaliana. The distribution patterns of epitopes associated with methyl-esterified homogalacturonan in leaves and hypocotyls of wild-type (WT) and ADK-deficient plants were examined using immunolocalization and biochemical techniques. JIM5 and LM7 epitopes, characteristic of low esterified pectins, were more irregularly distributed along the cell wall in ADK-deficient plants than in WT cell walls. In addition, epitopes recognized by JIM7, characteristic of pectins with a higher degree of methyl-esterification, were less abundant in ADK-deficient leaves and hypocotyls. Since de-esterified pectins have enhanced adhesion properties, we propose that the higher abundance and the altered distribution of low methyl-esterified pectin in ADK-deficient cell walls lead to the leaf shape abnormalities observed in these plants.

  5. Generation of EMS-Mutagenized Populations of Arabidopsis thaliana for Polyamine Genetics.

    PubMed

    Atanasov, Kostadin E; Liu, Changxin; Tiburcio, Antonio F; Alcázar, Rubén

    2018-01-01

    In the recent years, genetic engineering of polyamine biosynthetic genes has provided evidence for their involvement in plant stress responses and different aspects of plant development. Such approaches are being complemented with the use of reverse genetics, in which mutants affected on a particular trait, tightly associated with polyamines, are isolated and the causal genes mapped. Reverse genetics enables the identification of novel genes in the polyamine pathway, which may be involved in downstream signaling, transport, homeostasis, or perception. Here, we describe a basic protocol for the generation of ethyl methanesulfonate (EMS) mutagenized populations of Arabidopsis thaliana for its use in reverse genetics applied to polyamines.

  6. Functional Redundancy and Divergence within the Arabidopsis RETICULATA-RELATED Gene Family1[W][OA

    PubMed Central

    Pérez-Pérez, José Manuel; Esteve-Bruna, David; González-Bayón, Rebeca; Kangasjärvi, Saijaliisa; Caldana, Camila; Hannah, Matthew A.; Willmitzer, Lothar; Ponce, María Rosa; Micol, José Luis

    2013-01-01

    A number of Arabidopsis (Arabidopsis thaliana) mutants exhibit leaf reticulation, having green veins that stand out against paler interveinal tissues, fewer cells in the interveinal mesophyll, and normal perivascular bundle sheath cells. Here, to examine the basis of leaf reticulation, we analyzed the Arabidopsis RETICULATA-RELATED (RER) gene family, several members of which cause leaf reticulation when mutated. Although transcripts of RE, RER1, and RER3 were mainly detected in the bundle sheath cells of expanded leaves, functional RER3:GREEN FLUORESCENT PROTEIN was visualized in the chloroplast membranes of all photosynthetic cells. Leaf reticulation in the re and rer3 loss-of-function mutants occurred, along with accumulation of reactive oxygen species, in a photoperiod-dependent manner. A comparison of re and rer3 leaf messenger RNA expression profiles showed more than 200 genes were similarly misexpressed in both mutants. In addition, metabolic profiles of mature leaves revealed that several biosynthetic pathways downstream of pyruvate are altered in re and rer3. Double mutant analysis showed that only re rer1 and rer5 rer6 exhibited synergistic phenotypes, indicating functional redundancy. The redundancy between RE and its closest paralog, RER1, was confirmed by overexpressing RER1 in re mutants, which partially suppressed leaf reticulation. Our results show that RER family members can be divided into four functional modules with divergent functions. Moreover, these results provide insights into the origin of the reticulated phenotype, suggesting that the RER proteins functionally interconnect photoperiodic growth, amino acid homeostasis, and reactive oxygen species metabolism during Arabidopsis leaf growth. PMID:23596191

  7. Analysis of protein interactions within the cytokinin-signaling pathway of Arabidopsis thaliana.

    PubMed

    Dortay, Hakan; Mehnert, Nijuscha; Bürkle, Lukas; Schmülling, Thomas; Heyl, Alexander

    2006-10-01

    The signal of the plant hormone cytokinin is perceived by membrane-located sensor histidine kinases and transduced by other members of the plant two-component system. In Arabidopsis thaliana, 28 two-component system proteins (phosphotransmitters and response regulators) act downstream of three receptors, transmitting the signal from the membrane to the nucleus and modulating the cellular response. Although the principal signaling mechanism has been elucidated, redundancy in the system has made it difficult to understand which of the many components interact to control the downstream biological processes. Here, we present a large-scale interaction study comprising most members of the Arabidopsis cytokinin signaling pathway. Using the yeast two-hybrid system, we detected 42 new interactions, of which more than 90% were confirmed by in vitro coaffinity purification. There are distinct patterns of interaction between protein families, but only a few interactions between proteins of the same family. An interaction map of this signaling pathway shows the Arabidopsis histidine phosphotransfer proteins as hubs, which interact with members from all other protein families, mostly in a redundant fashion. Domain-mapping experiments revealed the interaction domains of the proteins of this pathway. Analyses of Arabidopsis histidine phosphotransfer protein 5 mutant proteins showed that the presence of the canonical phospho-accepting histidine residue is not required for the interactions. Interaction of A-type response regulators with Arabidopsis histidine phosphotransfer proteins but not with B-type response regulators suggests that their known activity in feedback regulation may be realized by interfering at the level of Arabidopsis histidine phosphotransfer protein-mediated signaling. This study contributes to our understanding of the protein interactions of the cytokinin-signaling system and provides a framework for further functional studies in planta.

  8. Genetic and Phenotypic Analysis of Lateral Root Development in Arabidopsis thaliana.

    PubMed

    Napsucialy-Mendivil, Selene; Dubrovsky, Joseph G

    2018-01-01

    Root system formation to a great extent depends on lateral root (LR) formation. In Arabidopsis thaliana, LRs are initiated within a parent root in pericycle that is an external tissue of the stele. LR initiation takes place in a strictly acropetal pattern, whereas posterior lateral root primordium (LRP) formation is asynchronous. In this chapter, we focus on methods of genetic and phenotypic analysis of LR initiation, LRP morphogenesis, and LR emergence in Arabidopsis. We provide details on how to make cleared root preparations and how to identify the LRP stages. We also pay attention to the categorization of the LRP developmental stages and their variations and to the normalization of the number of LRs and LRPs formed, per length of the primary root, and per number of cells produced within a root. Hormonal misbalances and mutations affect LRP morphogenesis significantly, and the evaluation of LRP abnormalities is addressed as well. Finally, we deal with various molecular markers that can be used for genetic and phenotypic analyses of LR development.

  9. Evaluation of Arabidopsis thaliana as a model host for Xylella fastidiosa.

    PubMed

    Rogers, Elizabeth E

    2012-06-01

    The bacterium Xylella fastidiosa causes a number of plant diseases of significant economic impact. To date, progress determining mechanisms of host-plant susceptibility, tolerance, or resistance has been slow, due in large part to the long generation time and limited available genetic resources for grape, almond, and other known hosts of X. fastidiosa. To overcome many of these limitations, Arabidopsis thaliana has been evaluated as a host for X. fastidiosa. A pin-prick inoculation method has been developed to infect Arabidopsis with X. fastidiosa. Following infection, X. fastidiosa multiplies and can be detected by microscopy, polymerase chain reaction, and isolation. The ecotypes Van-0, LL-0, and Tsu-1 all allow more growth of strain X. fastidiosa Temecula than the reference ecotype Col-0. Affymetrix ATH1 microarray analysis of inoculated vs. noninoculated Tsu-1 reveals gene expression changes that differ greatly from changes seen after infection with apoplast-colonizing bacteria such as Psuedomonas syringae pvs. tomato or syringae. Many genes responsive to oxidative stress are differentially regulated, while classic pathogenesis-related genes are not induced by X. fastidiosa infection.

  10. Sequence and analysis of chromosome 2 of the plant Arabidopsis thaliana.

    PubMed

    Lin, X; Kaul, S; Rounsley, S; Shea, T P; Benito, M I; Town, C D; Fujii, C Y; Mason, T; Bowman, C L; Barnstead, M; Feldblyum, T V; Buell, C R; Ketchum, K A; Lee, J; Ronning, C M; Koo, H L; Moffat, K S; Cronin, L A; Shen, M; Pai, G; Van Aken, S; Umayam, L; Tallon, L J; Gill, J E; Adams, M D; Carrera, A J; Creasy, T H; Goodman, H M; Somerville, C R; Copenhaver, G P; Preuss, D; Nierman, W C; White, O; Eisen, J A; Salzberg, S L; Fraser, C M; Venter, J C

    1999-12-16

    Arabidopsis thaliana (Arabidopsis) is unique among plant model organisms in having a small genome (130-140 Mb), excellent physical and genetic maps, and little repetitive DNA. Here we report the sequence of chromosome 2 from the Columbia ecotype in two gap-free assemblies (contigs) of 3.6 and 16 megabases (Mb). The latter represents the longest published stretch of uninterrupted DNA sequence assembled from any organism to date. Chromosome 2 represents 15% of the genome and encodes 4,037 genes, 49% of which have no predicted function. Roughly 250 tandem gene duplications were found in addition to large-scale duplications of about 0.5 and 4.5 Mb between chromosomes 2 and 1 and between chromosomes 2 and 4, respectively. Sequencing of nearly 2 Mb within the genetically defined centromere revealed a low density of recognizable genes, and a high density and diverse range of vestigial and presumably inactive mobile elements. More unexpected is what appears to be a recent insertion of a continuous stretch of 75% of the mitochondrial genome into chromosome 2.

  11. EDS1 contributes to nonhost resistance of Arabidopsis thaliana against Erwinia amylovora.

    PubMed

    Moreau, Manon; Degrave, Alexandre; Vedel, Régine; Bitton, Frédérique; Patrit, Oriane; Renou, Jean-Pierre; Barny, Marie-Anne; Fagard, Mathilde

    2012-03-01

    Erwinia amylovora causes fire blight in rosaceous plants. In nonhost Arabidopsis thaliana, E. amylovora triggers necrotic symptoms associated with transient bacterial multiplication, suggesting either that A. thaliana lacks a susceptibility factor or that it actively restricts E. amylovora growth. Inhibiting plant protein synthesis at the time of infection led to an increase in necrosis and bacterial multiplication and reduced callose deposition, indicating that A. thaliana requires active protein synthesis to restrict E. amylovora growth. Analysis of the callose synthase-deficient pmr4-1 mutant indicated that lack of callose deposition alone did not lead to increased sensitivity to E. amylovora. Transcriptome analysis revealed that approximately 20% of the genes induced following E. amylovora infection are related to defense and signaling. Analysis of mutants affected in NDR1 and EDS1, two main components of the defense-gene activation observed, revealed that E. amylovora multiplied ten times more in the eds1-2 mutant than in the wild type but not in the ndr1-1 mutant. Analysis of mutants affected in three WRKY transcription factors showing EDS1-dependent activation identified WRKY46 and WRKY54 as positive regulators and WRKY70 as a negative regulator of defense against E. amylovora. Altogether, we show that EDS1 is a positive regulator of nonhost resistance against E. amylovora in A. thaliana and hypothesize that it controls the production of several effective defenses against E. amylovora through the action of WRKY46 and WRKY54, while WRKY70 acts as a negative regulator.

  12. Disintegration of microtubules in Arabidopsis thaliana and bladder cancer cells by isothiocyanates

    PubMed Central

    Øverby, Anders; Bævre, Mette S.; Thangstad, Ole P.; Bones, Atle M.

    2015-01-01

    Isothiocyanates (ITCs) from biodegradation of glucosinolates comprise a group of electrophiles associated with growth-inhibitory effects in plant- and mammalian cells. The underlying modes of action of this feature are not fully understood. Clarifying this has involved mammalian cancer cells due to ITCs' chemopreventive potential. The binding of ITCs to tubulins has been reported as a mechanism by which ITCs induce cell cycle arrest and apoptosis. In the present study we demonstrate that ITCs disrupt microtubules in Arabidopsis thaliana contributing to the observed inhibited growth phenotype. We also confirmed this in rat bladder cancer cells (AY-27) suggesting that cells from plant and animals share mechanisms by which ITCs affect growth. Exposure of A. thaliana to vapor-phase of allyl ITC (AITC) inhibited growth and induced a concurrent bleaching of leaves in a dose-dependent manner. Transcriptional analysis was used to show an upregulation of heat shock-genes upon AITC-treatment. Transgenic A. thaliana expressing GFP-marked α-tubulin was employed to show a time- and dose-dependent disintegration of microtubules by AITC. Treatment of AY-27 with ITCs resulted in a time- and dose-dependent decrease of cell proliferation and G2/M-arrest. AY-27 transiently transfected to express GFP-tagged α-tubulin were treated with ITCs resulting in a loss of microtubular filaments and the subsequent formation of apoptotic bodies. In conclusion, our data demonstrate an ITC-induced mechanism leading to growth inhibition in A. thaliana and rat bladder cancer cells, and expose clues to the mechanisms underlying the physiological role of glucosinolates in vivo. PMID:25657654

  13. Inflorescence photosynthetic contribution to fitness releases Arabidopsis thaliana plants from trade-off constraints on early flowering.

    PubMed

    Gnan, Sebastian; Marsh, Tom; Kover, Paula X

    2017-01-01

    Leaves are thought to be the primary carbon source for reproduction in plants, so a positive relationship between vegetative size and reproductive output is expected, establishing a trade-off between time to reproduction and reproductive output. A common response to higher temperatures due to climate changes is the induction of earlier transition into reproduction. Thus, in annual plants, earlier transition into flowering can potentially constrain plant size and reduce seed production. However, trade-offs between early reproduction and fitness are not always observed, suggesting mechanisms to escape the constraints of early flowering do exist. Here, we test whether inflorescence photosynthesis contribution to the reproductive output of Arabidopsis thaliana can offset the cost of early reproduction. We followed the development, growth rate and fitness of 15 accessions, and removed all rosette leaves at flowering (prior to the completion of inflorescence development or any fruit production) in half of the plants to determine the ability of inflorescences to maintain fitness in the absence of leaves. Although leaf removal significantly reduced fruit number, seed weight and plant height, even the most severely impacted accessions maintained 35% of their fitness with the inflorescence as the sole photosynthetic organ; and some accessions experienced no reduction in fitness. Differences between accessions in their ability to maintain fitness after leaf removal is best explained by earlier flowering time and the ability to maintain as many or more branches after leaf removal as in the control treatment. Although earlier flowering does constrain plant vegetative size, we found that inflorescence photosynthesis can significantly contribute to seed production, explaining why early flowering plants can maintain high fitness despite a reduction in vegetative size. Thus, plants can be released from the usually assumed trade-offs associated with earlier reproduction, and

  14. AGO6 functions in RNA-mediated transcriptional gene silencing in shoot and root meristems in Arabidopsis thaliana.

    PubMed

    Eun, Changho; Lorkovic, Zdravko J; Naumann, Ulf; Long, Quan; Havecker, Ericka R; Simon, Stacey A; Meyers, Blake C; Matzke, Antonius J M; Matzke, Marjori

    2011-01-01

    RNA-directed DNA methylation (RdDM) is a small interfering RNA (siRNA)-mediated epigenetic modification that contributes to transposon silencing in plants. RdDM requires a complex transcriptional machinery that includes specialized RNA polymerases, named Pol IV and Pol V, as well as chromatin remodelling proteins, transcription factors, RNA binding proteins, and other plant-specific proteins whose functions are not yet clarified. In Arabidopsis thaliana, DICER-LIKE3 and members of the ARGONAUTE4 group of ARGONAUTE (AGO) proteins are involved, respectively, in generating and using 24-nt siRNAs that trigger methylation and transcriptional gene silencing of homologous promoter sequences. AGO4 is the main AGO protein implicated in the RdDM pathway. Here we report the identification of the related AGO6 in a forward genetic screen for mutants defective in RdDM and transcriptional gene silencing in shoot and root apical meristems in Arabidopsis thaliana. The identification of AGO6, and not AGO4, in our screen is consistent with the primary expression of AGO6 in shoot and root growing points.

  15. Activation of Arabidopsis Seed Hair Development by Cotton Fiber-Related Genes

    PubMed Central

    Pang, Mingxiong; Shi, Xiaoli; Stelly, David M.; Chen, Z. Jeffrey

    2011-01-01

    Each cotton fiber is a single-celled seed trichome or hair, and over 20,000 fibers may develop semi-synchronously on each seed. The molecular basis for seed hair development is unknown but is likely to share many similarities with leaf trichome development in Arabidopsis. Leaf trichome initiation in Arabidopsis thaliana is activated by GLABROUS1 (GL1) that is negatively regulated by TRIPTYCHON (TRY). Using laser capture microdissection and microarray analysis, we found that many putative MYB transcription factor and structural protein genes were differentially expressed in fiber and non-fiber tissues. Gossypium hirsutum MYB2 (GhMYB2), a putative GL1 homolog, and its downstream gene, GhRDL1, were highly expressed during fiber cell initiation. GhRDL1, a fiber-related gene with unknown function, was predominately localized around cell walls in stems, sepals, seed coats, and pollen grains. GFP:GhRDL1 and GhMYB2:YFP were co-localized in the nuclei of ectopic trichomes in siliques. Overexpressing GhRDL1 or GhMYB2 in A. thaliana Columbia-0 (Col-0) activated fiber-like hair production in 4–6% of seeds and had on obvious effects on trichome development in leaves or siliques. Co-overexpressing GhRDL1 and GhMYB2 in A. thaliana Col-0 plants increased hair formation in ∼8% of seeds. Overexpressing both GhRDL1 and GhMYB2 in A. thaliana Col-0 try mutant plants produced seed hair in ∼10% of seeds as well as dense trichomes inside and outside siliques, suggesting synergistic effects of GhRDL1 and GhMYB2 with try on development of trichomes inside and outside of siliques and seed hair in A. thaliana. These data suggest that a different combination of factors is required for the full development of trichomes (hairs) in leaves, siliques, and seeds. A. thaliana can be developed as a model a system for discovering additional genes that control seed hair development in general and cotton fiber in particular. PMID:21779324

  16. Reverse-engineering the Arabidopsis thaliana transcriptional network under changing environmental conditions

    PubMed Central

    Carrera, Javier; Rodrigo, Guillermo; Jaramillo, Alfonso; Elena, Santiago F

    2009-01-01

    Background Understanding the molecular mechanisms plants have evolved to adapt their biological activities to a constantly changing environment is an intriguing question and one that requires a systems biology approach. Here we present a network analysis of genome-wide expression data combined with reverse-engineering network modeling to dissect the transcriptional control of Arabidopsis thaliana. The regulatory network is inferred by using an assembly of microarray data containing steady-state RNA expression levels from several growth conditions, developmental stages, biotic and abiotic stresses, and a variety of mutant genotypes. Results We show that the A. thaliana regulatory network has the characteristic properties of hierarchical networks. We successfully applied our quantitative network model to predict the full transcriptome of the plant for a set of microarray experiments not included in the training dataset. We also used our model to analyze the robustness in expression levels conferred by network motifs such as the coherent feed-forward loop. In addition, the meta-analysis presented here has allowed us to identify regulatory and robust genetic structures. Conclusions These data suggest that A. thaliana has evolved high connectivity in terms of transcriptional regulation among cellular functions involved in response and adaptation to changing environments, while gene networks constitutively expressed or less related to stress response are characterized by a lower connectivity. Taken together, these findings suggest conserved regulatory strategies that have been selected during the evolutionary history of this eukaryote. PMID:19754933

  17. The histone acetyltransferase GCN5 and the transcriptional coactivator ADA2b affect leaf development and trichome morphogenesis in Arabidopsis.

    PubMed

    Kotak, Jenna; Saisana, Marina; Gegas, Vasilis; Pechlivani, Nikoletta; Kaldis, Athanasios; Papoutsoglou, Panagiotis; Makris, Athanasios; Burns, Julia; Kendig, Ashley L; Sheikh, Minnah; Kuschner, Cyrus E; Whitney, Gabrielle; Caiola, Hanna; Doonan, John H; Vlachonasios, Konstantinos E; McCain, Elizabeth R; Hark, Amy T

    2018-05-30

    The histone acetyltransferase GCN5 and associated transcriptional coactivator ADA2b are required to couple endoreduplication and trichome branching. Mutation of ADA2b also disrupts the relationship between ploidy and leaf cell size. Dynamic chromatin structure has been established as a general mechanism by which gene function is temporally and spatially regulated, but specific chromatin modifier function is less well understood. To address this question, we have investigated the role of the histone acetyltransferase GCN5 and the associated coactivator ADA2b in developmental events in Arabidopsis thaliana. Arabidopsis plants with T-DNA insertions in GCN5 (also known as HAG1) or ADA2b (also known as PROPORZ1) display pleiotropic phenotypes including dwarfism and floral defects affecting fertility. We undertook a detailed characterization of gcn5 and ada2b phenotypic effects in rosette leaves and trichomes to establish a role for epigenetic control in these developmental processes. ADA2b and GCN5 play specific roles in leaf tissue, affecting cell growth and division in rosette leaves often in complex and even opposite directions. Leaves of gcn5 plants display overall reduced ploidy levels, while ada2b-1 leaves show increased ploidy. Endoreduplication leading to increased ploidy is also known to contribute to normal trichome morphogenesis. We demonstrate that gcn5 and ada2b mutants display alterations in the number and patterning of trichome branches, with ada2b-1 and gcn5-1 trichomes being significantly less branched, while gcn5-6 trichomes show increased branching. Elongation of the trichome stalk and branches also vary in different mutant backgrounds, with stalk length having an inverse relationship with branch number. Taken together, our data indicate that, in Arabidopsis, leaves and trichomes ADA2b and GCN5 are required to couple nuclear content with cell growth and morphogenesis.

  18. Regulation of Arabidopsis Leaf Hydraulics Involves Light-Dependent Phosphorylation of Aquaporins in Veins[C][W

    PubMed Central

    Prado, Karine; Boursiac, Yann; Tournaire-Roux, Colette; Monneuse, Jean-Marc; Postaire, Olivier; Da Ines, Olivier; Schäffner, Anton R.; Hem, Sonia; Santoni, Véronique; Maurel, Christophe

    2013-01-01

    The water status of plant leaves depends on the efficiency of the water supply, from the vasculature to inner tissues. This process is under hormonal and environmental regulation and involves aquaporin water channels. In Arabidopsis thaliana, the rosette hydraulic conductivity (Kros) is higher in darkness than it is during the day. Knockout plants showed that three plasma membrane intrinsic proteins (PIPs) sharing expression in veins (PIP1;2, PIP2;1, and PIP2;6) contribute to rosette water transport, and PIP2;1 can fully account for Kros responsiveness to darkness. Directed expression of PIP2;1 in veins of a pip2;1 mutant was sufficient to restore Kros. In addition, a positive correlation, in both wild-type and PIP2;1-overexpressing plants, was found between Kros and the osmotic water permeability of protoplasts from the veins but not from the mesophyll. Thus, living cells in veins form a major hydraulic resistance in leaves. Quantitative proteomic analyses showed that light-dependent regulation of Kros is linked to diphosphorylation of PIP2;1 at Ser-280 and Ser-283. Expression in pip2;1 of phosphomimetic and phosphorylation-deficient forms of PIP2;1 demonstrated that phosphorylation at these two sites is necessary for Kros enhancement under darkness. These findings establish how regulation of a single aquaporin isoform in leaf veins critically determines leaf hydraulics. PMID:23532070

  19. Chemical Inhibition of a Subset of Arabidopsis thaliana GSK3-like Kinases Activates Brassinosteroid Signaling

    PubMed Central

    De Rybel, Bert; Audenaert, Dominique; Vert, Grégory; Rozhon, Wilfried; Mayerhofer, Juliane; Peelman, Frank; Coutuer, Silvie; Denayer, Tinneke; Jansen, Leentje; Nguyen, Long; Vanhoutte, Isabelle; Beemster, Gerrit T.S.; Vleminckx, Kris; Jonak, Claudia; Chory, Joanne; Inzé, Dirk; Russinova, Eugenia; Beeckman, Tom

    2016-01-01

    SUMMARY Glycogen synthase kinase 3 (GSK3) is a key regulator in signaling pathways in both animals and plants. Three Arabidopsis thaliana GSK3s are shown to be related to brassinosteroid (BR) signaling. In a phenotype-based compound screen we identified bikinin, a small molecule that activates BR signaling downstream of the BR receptor. Bikinin directly binds the GSK3 BIN2 and acts as an ATP competitor. Furthermore, bikinin inhibits the activity of six other Arabidopsis GSK3s. Genome-wide transcript analyses demonstrate that simultaneous inhibition of seven GSK3s is sufficient to activate BR responses. Our data suggest that GSK3 inhibition is the sole activation mode of BR signaling and argues against GSK3-independent BR responses in Arabidopsis. The opportunity to generate multiple and conditional knockouts in key regulators in the BR signaling pathway by bikinin represents a useful tool to further unravel regulatory mechanisms. PMID:19549598

  20. Analysis of Circadian Leaf Movements.

    PubMed

    Müller, Niels A; Jiménez-Gómez, José M

    2016-01-01

    The circadian clock is a molecular timekeeper that controls a wide variety of biological processes. In plants, clock outputs range from the molecular level, with rhythmic gene expression and metabolite content, to physiological processes such as stomatal conductance or leaf movements. Any of these outputs can be used as markers to monitor the state of the circadian clock. In the model plant Arabidopsis thaliana, much of the current knowledge about the clock has been gained from time course experiments profiling expression of endogenous genes or reporter constructs regulated by the circadian clock. Since these methods require labor-intensive sample preparation or transformation, monitoring leaf movements is an interesting alternative, especially in non-model species and for natural variation studies. Technological improvements both in digital photography and image analysis allow cheap and easy monitoring of circadian leaf movements. In this chapter we present a protocol that uses an autonomous point and shoot camera and free software to monitor circadian leaf movements in tomato.

  1. Yeast Methylotrophy and Autophagy in a Methanol-Oscillating Environment on Growing Arabidopsis thaliana Leaves

    PubMed Central

    Kawaguchi, Kosuke; Yurimoto, Hiroya; Oku, Masahide; Sakai, Yasuyoshi

    2011-01-01

    The yeast Candida boidinii capable of growth on methanol proliferates and survives on the leaves of Arabidopsis thaliana. The local methanol concentration at the phyllosphere of growing A. thaliana exhibited daily periodicity, and yeast cells responded by altering both the expression of methanol-inducible genes and peroxisome proliferation. Even under these dynamically changing environmental conditions, yeast cells proliferated 3 to 4 times in 11 days. Among the C1-metabolic enzymes, enzymes in the methanol assimilation pathway, but not formaldehyde dissimilation or anti-oxidizing enzymes, were necessary for yeast proliferation at the phyllosphere. Furthermore, both peroxisome assembly and pexophagy, a selective autophagy pathway that degrades peroxisomes, were necessary for phyllospheric proliferation. Thus, the present study sheds light on the life cycle and physiology of yeast in the natural environment at both the molecular and cellular levels. PMID:21966472

  2. A non-canonical transferred DNA insertion at the BRI1 locus in Arabidopsis thaliana.

    PubMed

    Zhao, Zhong; Zhu, Yan; Erhardt, Mathieu; Ruan, Ying; Shen, Wen-Hui

    2009-04-01

    Agrobacterium-mediated transformation is widely used in transgenic plant engineering and has been proven to be a powerful tool for insertional mutagenesis of the plant genome. The transferred DNA (T-DNA) from Agrobacterium is integrated into the plant genome through illegitimate recombination between the T-DNA and the plant DNA. Contrasting to the canonical insertion, here we report on a locus showing a complex mutation associated with T-DNA insertion at the BRI1 gene in Arabidopsis thaliana. We obtained a mutant line, named salade for its phenotype of dwarf stature and proliferating rosette. Molecular characterization of this mutant revealed that in addition to T-DNA a non-T-DNA-localized transposon from bacteria was inserted in the Arabidopsis genome and that a region of more than 11.5 kb of the Arabidopsis genome was deleted at the insertion site. The deleted region contains the brassinosteroid receptor gene BRI1 and the transcription factor gene WRKY13. Our finding reveals non-canonical T-DNA insertion, implicating horizontal gene transfer and cautioning the use of T-DNA as mutagen in transgenic research.

  3. Environmental Heat and Salt Stress Induce Transgenerational Phenotypic Changes in Arabidopsis thaliana

    PubMed Central

    Suter, Léonie; Widmer, Alex

    2013-01-01

    Plants that can adapt their phenotype may be more likely to survive changing environmental conditions. Heritable epigenetic variation could provide a way to rapidly adapt to such changes. Here we tested whether environmental stress induces heritable, potentially adaptive phenotypic changes independent of genetic variation over few generations in Arabidopsis thaliana. We grew two accessions (Col-0, Sha-0) of A. thaliana for three generations under salt, heat and control conditions and tested for induced heritable phenotypic changes in the fourth generation (G4) and in reciprocal F1 hybrids generated in generation three. Using these crosses we further tested whether phenotypic changes were maternally or paternally transmitted. In generation five (G5), we assessed whether phenotypic effects persisted over two generations in the absence of stress. We found that exposure to heat stress in previous generations accelerated flowering under G4 control conditions in Sha-0, but heritable effects disappeared in G5 after two generations without stress exposure. Previous exposure to salt stress increased salt tolerance in one of two reciprocal F1 hybrids. Transgenerational effects were maternally and paternally inherited. Lacking genetic variability, maternal and paternal inheritance and reversibility of transgenerational effects together indicate that stress can induce heritable, potentially adaptive phenotypic changes, probably through epigenetic mechanisms. These effects were strongly dependent on plant genotype and may not be a general response to stress in A. thaliana. PMID:23585834

  4. Hydroxymethylated Dioxobilins in Senescent Arabidopsis thaliana Leaves: Sign of a Puzzling Biosynthetic Intermezzo of Chlorophyll Breakdown.

    PubMed

    Süssenbacher, Iris; Kreutz, Christoph R; Christ, Bastien; Hörtensteiner, Stefan; Kräutler, Bernhard

    2015-08-10

    1-Formyl-19-oxobilin-type tetrapyrroles are characteristic, abundant products of chlorophyll breakdown in senescent leaves. However, in some leaves, 1,19-dioxobilin-type chlorophyll catabolites (DCCs) lacking the formyl group accumulate instead. A P450 enzyme was identified in in vitro studies that removed the formyl group of a primary fluorescent chlorophyll catabolite (pFCC) and generated fluorescent DCCs. These DCCs are precursors of isomeric nonfluorescent DCCs (NDCCs). Here, we report a structural investigation of the NDCCs in senescent leaves of wild-type Arabidopsis thaliana. Four new NDCCs were characterized, two of which carried a stereoselectively added hydroxymethyl group. Such formal DCC hydroxymethylations were previously found in DCCs in leaves of a mutant of A. thaliana. They are now indicated to be a feature of chlorophyll breakdown in A. thaliana, associated with the specific in vivo deformylation of pFCC en route to NDCCs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Local Populations of Arabidopsis thaliana Show Clear Relationship between Photoperiodic Sensitivity of Flowering Time and Altitude

    PubMed Central

    Lewandowska-Sabat, Anna M.; Fjellheim, Siri; Olsen, Jorunn E.; Rognli, Odd A.

    2017-01-01

    Adaptation of plants to local conditions that vary substantially within their geographic range is essential for seasonal timing of flowering, a major determinant of plant reproductive success. This study investigates photoperiodic responses in natural populations of Arabidopsis thaliana from high northern latitudes and their significance for local adaptation. Thirty lineages from ten local A. thaliana populations, representing different locations across an altitudinal gradient (2–850 m a.s.l.) in Norway, were grown under uniform controlled conditions, and used to screen for responses to five different photoperiods. We studied relationships between variation in photoperiodic sensitivity of flowering time, altitude, and climatic factors associated with the sites of origin. We found that variation in response to photoperiod is significantly correlated with altitude and climatic variables associated with the sites of origin of the populations. Populations originating from lower altitudes showed stronger photoperiodic sensitivity than populations from higher altitudes. Our results indicate that the altitudinal climatic gradient generates clinal variation in adaptive traits in A. thaliana. PMID:28659966

  6. Carpeloidy in flower evolution and diversification: a comparative study in Carica papaya and Arabidopsis thaliana

    PubMed Central

    Ronse De Craene, Louis; Tréhin, Christophe; Morel, Patrice; Negrutiu, Ioan

    2011-01-01

    Background and Aims Bisexual flowers of Carica papaya range from highly regular flowers to morphs with various fusions of stamens to the ovary. Arabidopsis thaliana sup1 mutants have carpels replaced by chimeric carpel–stamen structures. Comparative analysis of stamen to carpel conversions in the two different plant systems was used to understand the stage and origin of carpeloidy when derived from stamen tissues, and consequently to understand how carpeloidy contributes to innovations in flower evolution. Methods Floral development of bisexual flowers of Carica was studied by scanning electron microscopy and was compared with teratological sup mutants of A. thaliana. Key Results In Carica development of bisexual flowers was similar to wild (unisexual) forms up to locule initiation. Feminization ranges from fusion of stamen tissue to the gynoecium to complete carpeloidy of antepetalous stamens. In A. thaliana, partial stamen feminization occurs exclusively at the flower apex, with normal stamens forming at the periphery. Such transformations take place relatively late in development, indicating strong developmental plasticity of most stamen tissues. These results are compared with evo-devo theories on flower bisexuality, as derived from unisexual ancestors. The Arabidopsis data highlight possible early evolutionary events in the acquisition of bisexuality by a patchy transformation of stamen parts into female parts linked to a flower axis-position effect. The Carica results highlight tissue-fusion mechanisms in angiosperms leading to carpeloidy once bisexual flowers have evolved. Conclusions We show two different developmental routes leading to stamen to carpel conversions by late re-specification. The process may be a fundamental aspect of flower development that is hidden in most instances by developmental homeostasis. PMID:21504912

  7. Altered gene expression changes in Arabidopsis leaf tissues and protoplasts in response to Plum pox virus infection

    PubMed Central

    Babu, Mohan; Griffiths, Jonathan S; Huang, Tyng-Shyan; Wang, Aiming

    2008-01-01

    Background Virus infection induces the activation and suppression of global gene expression in the host. Profiling gene expression changes in the host may provide insights into the molecular mechanisms that underlie host physiological and phenotypic responses to virus infection. In this study, the Arabidopsis Affymetrix ATH1 array was used to assess global gene expression changes in Arabidopsis thaliana plants infected with Plum pox virus (PPV). To identify early genes in response to PPV infection, an Arabidopsis synchronized single-cell transformation system was developed. Arabidopsis protoplasts were transfected with a PPV infectious clone and global gene expression changes in the transfected protoplasts were profiled. Results Microarray analysis of PPV-infected Arabidopsis leaf tissues identified 2013 and 1457 genes that were significantly (Q ≤ 0.05) up- (≥ 2.5 fold) and downregulated (≤ -2.5 fold), respectively. Genes associated with soluble sugar, starch and amino acid, intracellular membrane/membrane-bound organelles, chloroplast, and protein fate were upregulated, while genes related to development/storage proteins, protein synthesis and translation, and cell wall-associated components were downregulated. These gene expression changes were associated with PPV infection and symptom development. Further transcriptional profiling of protoplasts transfected with a PPV infectious clone revealed the upregulation of defence and cellular signalling genes as early as 6 hours post transfection. A cross sequence comparison analysis of genes differentially regulated by PPV-infected Arabidopsis leaves against uniEST sequences derived from PPV-infected leaves of Prunus persica, a natural host of PPV, identified orthologs related to defence, metabolism and protein synthesis. The cross comparison of genes differentially regulated by PPV infection and by the infections of other positive sense RNA viruses revealed a common set of 416 genes. These identified genes

  8. Cadmium-sensitive, cad1 mutants of Arabidopsis thaliana are phytochelatin deficient.

    PubMed Central

    Howden, R; Goldsbrough, P B; Andersen, C R; Cobbett, C S

    1995-01-01

    An allelic series of cad1, cadmium-sensitive mutants of Arabidopsis thaliana, was isolated. These mutants were sensitive to cadmium to different extents and were deficient in their ability to form cadmium-peptide complexes as detected by gel-filtration chromatography. Each mutant was deficient in its ability to accumulate phytochelatins (PCs) as detected by high-performance liquid chromatography and the amount of PCs accumulated by each mutant correlated with its degree of sensitivity to cadmium. The mutants had wild-type levels of glutathione, the substrate for PC biosynthesis, and in vitro assays demonstrated that each of the mutants was deficient in PC synthase activity. These results demonstrate conclusively the importance of PCs for cadmium tolerance in plants. PMID:7770517

  9. High resolution imaging of subcellular glutathione concentrations by quantitative immunoelectron microscopy in different leaf areas of Arabidopsis

    PubMed Central

    Koffler, Barbara E.; Bloem, Elke; Zellnig, Günther; Zechmann, Bernd

    2013-01-01

    Glutathione is an important antioxidant and redox buffer in plants. It fulfills many important roles during plant development, defense and is essential for plant metabolism. Even though the compartment specific roles of glutathione during abiotic and biotic stress situations have been studied in detail there is still great lack of knowledge about subcellular glutathione concentrations within the different leaf areas at different stages of development. In this study a method is described that allows the calculation of compartment specific glutathione concentrations in all cell compartments simultaneously in one experiment by using quantitative immunogold electron microscopy combined with biochemical methods in different leaf areas of Arabidopsis thaliana Col-0 (center of the leaf, leaf apex, leaf base and leaf edge). The volume of subcellular compartments in the mesophyll of Arabidopsis was found to be similar to other plants. Vacuoles covered the largest volume within a mesophyll cell and increased with leaf age (up to 80% in the leaf apex of older leaves). Behind vacuoles, chloroplasts covered the second largest volume (up to 20% in the leaf edge of the younger leaves) followed by nuclei (up to 2.3% in the leaf edge of the younger leaves), mitochondria (up to 1.6% in the leaf apex of the younger leaves), and peroxisomes (up to 0.3% in the leaf apex of the younger leaves). These values together with volumes of the mesophyll determined by stereological methods from light and electron micrographs and global glutathione contents measured with biochemical methods enabled the determination of subcellular glutathione contents in mM. Even though biochemical investigations did not reveal differences in global glutathione contents, compartment specific differences could be observed in some cell compartments within the different leaf areas. Highest concentrations of glutathione were always found in mitochondria, where values in a range between 8.7 mM (in the apex of younger

  10. Melatonin induction and its role in high light stress tolerance in Arabidopsis thaliana.

    PubMed

    Lee, Hyoung Yool; Back, Kyoungwhan

    2018-05-16

    In plants, melatonin is a potent bioactive molecule involved in the response against various biotic and abiotic stresses. However, little is known of its defensive role against high light (HL) stress. In this study, we found that melatonin was transiently induced in response to HL stress in Arabidopsis thaliana with a simultaneous increase in the expression of melatonin biosynthetic genes, including serotonin N-acetyltransferase1 (SNAT1). Transient induction of melatonin was also observed in the flu mutant, a singlet oxygen ( 1 O 2 )-producing mutant, upon light exposure, suggestive of melatonin induction by chloroplastidic 1 O 2 against HL stress. An Arabidopsis snat1 mutant was devoid of melatonin induction upon HL stress, resulting in high susceptibility to HL stress. Exogenous melatonin treatment mitigated damage caused by HL stress in the snat1 mutant by reducing O 2 - production and increasing the expression of various ROS-responsive genes. In analogy, an Arabidopsis SNAT1-overexpressing line showed increased tolerance of HL stress concomitant with a reduction in malondialdehyde and ion leakage. A complementation line expressing an Arabidopsis SNAT1 genomic fragment in the snat1 mutant completely restored HL stress susceptibility in the snat1 mutant to levels comparable to that of wild-type Col-0 plants. The results of the analysis of several Arabidopsis genetic lines reveal for the first time at the genetic level that melatonin is involved in conferring HL stress tolerance in plants. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Changes in Polysome Association of mRNA Throughout Growth and Development in Arabidopsis thaliana.

    PubMed

    Yamasaki, Shotaro; Matsuura, Hideyuki; Demura, Taku; Kato, Ko

    2015-11-01

    Translational control is a key regulatory step in the expression of genes as proteins. In plant cells, the translational efficiency of mRNAs differs for different mRNA species, and the efficiency dynamically changes in various conditions. To gain a global view of translational control throughout growth and development, we performed genome-wide analysis of polysome association of mRNA during growth and leaf development in Arabidopsis thaliana by subjecting the mRNAs in polysomes to DNA microarray. This analysis revealed that the degree of polysome association of mRNA was different depending on the mRNA species, and the polysome association changed greatly throughout growth and development for each. In the growth stage, transcripts showed varying changes in polysome association from strongly depressed to unchanged, with the majority of transcripts showing dissociation from ribosomes. On the other hand, during leaf development, the polysome association of transcripts showed a normal distribution from repressed to activated mRNAs when comparing expanding and expanded leaves. In addition, functional category analysis of the microarray data suggested that translational control has a physiological significance in the plant growth and development process, especially in the categories of signaling and protein synthesis. In addition to this, we compared changes in polysome association of mRNAs between various conditions and characterized translational controls in each. This result suggested that mRNA translation might be controlled by complicated mechanisms for response to each condition. Our results highlight the importance of dynamic changes in mRNA translation in plant development and growth. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  12. Abscisic acid-regulated protein degradation causes osmotic stress-induced accumulation of branched-chain amino acids in Arabidopsis thaliana.

    PubMed

    Huang, Tengfang; Jander, Georg

    2017-10-01

    Whereas proline accumulates through de novo biosynthesis in plants subjected to osmotic stress, leucine, isoleucine, and valine accumulation in drought-stressed Arabidopsis thaliana is caused by abscisic acid-regulated protein degradation. In response to several kinds of abiotic stress, plants greatly increase their accumulation of free amino acids. Although stress-induced proline increases have been studied the most extensively, the fold-increase of other amino acids, in particular branched-chain amino acids (BCAAs; leucine, isoleucine, and valine), is often higher than that of proline. In Arabidopsis thaliana (Arabidopsis), BCAAs accumulate in response to drought, salt, mannitol, polyethylene glycol, herbicide treatment, and nitrogen starvation. Plants that are deficient in abscisic acid signaling accumulate lower amounts of BCAAs, but not proline and most other amino acids. Previous bioinformatic studies had suggested that amino acid synthesis, rather than protein degradation, is responsible for the observed BCAA increase in osmotically stressed Arabidopsis. However, whereas treatment with the protease inhibitor MG132 decreased drought-induced BCAA accumulation, inhibition of BCAA biosynthesis with the acetolactate synthase inhibitors chlorsulfuron and imazapyr did not. Additionally, overexpression of BRANCHED-CHAIN AMINO ACID TRANSFERASE2 (BCAT2), which is upregulated in response to osmotic stress and functions in BCAA degradation, decreased drought-induced BCAA accumulation. Together, these results demonstrate that BCAA accumulation in osmotically stressed Arabidopsis is primarily the result of protein degradation. After relief of the osmotic stress, BCAA homeostasis is restored over time by amino acid degradation involving BCAT2. Thus, drought-induced BCAA accumulation is different from that of proline, which is accumulated due to de novo synthesis in an abscisic acid-independent manner and remains elevated for a more prolonged period of time after removal of

  13. Growth platform-dependent and -independent phenotypic and metabolic responses of Arabidopsis and its halophytic relative, Eutrema salsugineum, to salt stress.

    PubMed

    Kazachkova, Yana; Batushansky, Albert; Cisneros, Aroldo; Tel-Zur, Noemi; Fait, Aaron; Barak, Simon

    2013-07-01

    Comparative studies of the stress-tolerant Arabidopsis (Arabidopsis thaliana) halophytic relative, Eutrema salsugineum, have proven a fruitful approach to understanding natural stress tolerance. Here, we performed comparative phenotyping of Arabidopsis and E. salsugineum vegetative development under control and salt-stress conditions, and then compared the metabolic responses of the two species on different growth platforms in a defined leaf developmental stage. Our results reveal both growth platform-dependent and -independent phenotypes and metabolic responses. Leaf emergence was affected in a similar way in both species grown in vitro but the effects observed in Arabidopsis occurred at higher salt concentrations in E. salsugineum. No differences in leaf emergence were observed on soil. A new effect of a salt-mediated reduction in E. salsugineum leaf area was unmasked. On soil, leaf area reduction in E. salsugineum was mainly due to a fall in cell number, whereas both cell number and cell size contributed to the decrease in Arabidopsis leaf area. Common growth platform-independent leaf metabolic signatures such as high raffinose and malate, and low fumarate contents that could reflect core stress tolerance mechanisms, as well as growth platform-dependent metabolic responses were identified. In particular, the in vitro growth platform led to repression of accumulation of many metabolites including sugars, sugar phosphates, and amino acids in E. salsugineum compared with the soil system where these same metabolites accumulated to higher levels in E. salsugineum than in Arabidopsis. The observation that E. salsugineum maintains salt tolerance despite growth platform-specific phenotypes and metabolic responses suggests a considerable degree of phenotypic and metabolic adaptive plasticity in this extremophile.

  14. A transcriptional dynamic network during Arabidopsis thaliana pollen development.

    PubMed

    Wang, Jigang; Qiu, Xiaojie; Li, Yuhua; Deng, Youping; Shi, Tieliu

    2011-01-01

    To understand transcriptional regulatory networks (TRNs), especially the coordinated dynamic regulation between transcription factors (TFs) and their corresponding target genes during development, computational approaches would represent significant advances in the genome-wide expression analysis. The major challenges for the experiments include monitoring the time-specific TFs' activities and identifying the dynamic regulatory relationships between TFs and their target genes, both of which are currently not yet available at the large scale. However, various methods have been proposed to computationally estimate those activities and regulations. During the past decade, significant progresses have been made towards understanding pollen development at each development stage under the molecular level, yet the regulatory mechanisms that control the dynamic pollen development processes remain largely unknown. Here, we adopt Networks Component Analysis (NCA) to identify TF activities over time course, and infer their regulatory relationships based on the coexpression of TFs and their target genes during pollen development. We carried out meta-analysis by integrating several sets of gene expression data related to Arabidopsis thaliana pollen development (stages range from UNM, BCP, TCP, HP to 0.5 hr pollen tube and 4 hr pollen tube). We constructed a regulatory network, including 19 TFs, 101 target genes and 319 regulatory interactions. The computationally estimated TF activities were well correlated to their coordinated genes' expressions during the development process. We clustered the expression of their target genes in the context of regulatory influences, and inferred new regulatory relationships between those TFs and their target genes, such as transcription factor WRKY34, which was identified that specifically expressed in pollen, and regulated several new target genes. Our finding facilitates the interpretation of the expression patterns with more biological

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

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

    Lundberg, Derek; Woyke, Tanja; Tringe, Susannah

    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 fewmore » 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.« less

  16. The Autophagic Degradation of Chloroplasts via Rubisco-Containing Bodies Is Specifically Linked to Leaf Carbon Status But Not Nitrogen Status in Arabidopsis1[W][OA

    PubMed Central

    Izumi, Masanori; Wada, Shinya; Makino, Amane; Ishida, Hiroyuki

    2010-01-01

    Autophagy is an intracellular process facilitating the vacuolar degradation of cytoplasmic components and is important for nutrient recycling during starvation. We previously demonstrated that chloroplasts can be partially mobilized to the vacuole by autophagy via spherical bodies named Rubisco-containing bodies (RCBs). Although chloroplasts contain approximately 80% of total leaf nitrogen and represent a major carbon and nitrogen source for new growth, the relationship between leaf nutrient status and RCB production remains unclear. We examined the effects of nutrient factors on the appearance of RCBs in leaves of transgenic Arabidopsis (Arabidopsis thaliana) expressing stroma-targeted fluorescent proteins. In excised leaves, the appearance of RCBs was suppressed by the presence of metabolic sugars, which were added externally or were produced during photosynthesis in the light. The light-mediated suppression was relieved by the inhibition of photosynthesis. During a diurnal cycle, RCB production was suppressed in leaves excised at the end of the day with high starch content. Starchless mutants phosphoglucomutase and ADP-Glc pyrophosphorylase1 produced a large number of RCBs, while starch-excess mutants starch-excess1 and maltose-excess1 produced fewer RCBs. In nitrogen-limited plants, as leaf carbohydrates were accumulated, RCB production was suppressed. We propose that there exists a close relationship between the degradation of chloroplast proteins via RCBs and leaf carbon but not nitrogen status in autophagy. We also found that the appearance of non-RCB-type autophagic bodies was not suppressed in the light and somewhat responded to nitrogen in excised leaves, unlike RCBs. These results imply that the degradation of chloroplast proteins via RCBs is specifically controlled in autophagy. PMID:20807997

  17. 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.

  18. Haemoglobin modulates NO emission and hyponasty under hypoxia-related stress in Arabidopsis thaliana.

    PubMed

    Hebelstrup, Kim H; van Zanten, Martijn; Mandon, Julien; Voesenek, Laurentius A C J; Harren, Frans J M; Cristescu, Simona M; Møller, Ian M; Mur, Luis A J

    2012-09-01

    Nitric oxide (NO) and ethylene are signalling molecules that are synthesized in response to oxygen depletion. Non-symbiotic plant haemoglobins (Hbs) have been demonstrated to act in roots under oxygen depletion to scavenge NO. Using Arabidopsis thaliana plants, the online emission of NO or ethylene was directly quantified under normoxia, hypoxia (0.1-1.0% O(2)), or full anoxia. The production of both gases was increased with reduced expression of either of the Hb genes GLB1 or GLB2, whereas NO emission decreased in plants overexpressing these genes. NO emission in plants with reduced Hb gene expression represented a major loss of nitrogen equivalent to 0.2mM nitrate per 24h under hypoxic conditions. Hb gene expression was greatly enhanced in flooded roots, suggesting induction by reduced oxygen diffusion. The function could be to limit loss of nitrogen under NO emission. NO reacts with thiols to form S-nitrosylated compounds, and it is demonstrated that hypoxia substantially increased the content of S-nitrosylated compounds. A parallel up-regulation of Hb gene expression in the normoxic shoots of the flooded plants may reflect signal transmission from root to shoot via ethylene and a role for Hb in the shoots. Hb gene expression was correlated with ethylene-induced upward leaf movement (hyponastic growth) but not with hypocotyl growth, which was Hb independent. Taken together the data suggest that Hb can influence flood-induced hyponasty via ethylene-dependent and, possibly, ethylene-independent pathways.

  19. The Role of Strigolactone in the Cross-Talk Between Arabidopsis thaliana and the Endophytic Fungus Mucor sp.

    PubMed Central

    Rozpądek, Piotr; Domka, Agnieszka M.; Nosek, Michał; Ważny, Rafał; Jędrzejczyk, Roman J.; Wiciarz, Monika; Turnau, Katarzyna

    2018-01-01

    Over the last years the role of fungal endophytes in plant biology has been extensively studied. A number of species were shown to positively affect plant growth and fitness, thus attempts have been made to utilize these microorganisms in agriculture and phytoremediation. Plant-fungi symbiosis requires multiple metabolic adjustments of both of the interacting organisms. The mechanisms of these adaptations are mostly unknown, however, plant hormones seem to play a central role in this process. The plant hormone strigolactone (SL) was previously shown to activate hyphae branching of mycorrhizal fungi and to negatively affect pathogenic fungi growth. Its role in the plant–endophytic fungi interaction is unknown. The effect of the synthetic SL analog GR24 on the endophytic fungi Mucor sp. growth, respiration, H2O2 production and the activity of antioxidant enzymes was evaluated. We found fungi colony growth rate was decreased in a GR24 concentration dependent manner. Additionally, the fungi accumulated more H2O2 what was accompanied by an altered activity of antioxidant enzymes. Symbiosis with Mucor sp. positively affected Arabidopsis thaliana growth, but SL was necessary for the establishment of the beneficial interaction. A. thaliana biosynthesis mutants max1 and max4, but not the SL signaling mutant max2 did not develop the beneficial phenotype. The negative growth response was correlated with alterations in SA homeostasis and a significant upregulation of genes encoding selected plant defensins. The fungi were also shown to be able to decompose SL in planta and to downregulate the expression of SL biosynthesis genes. Additionally, we have shown that GR24 treatment with a dose of 1 μM activates the production of SA in A. thaliana. The results presented here provide evidence for a role of SL in the plant–endophyte cross-talk during the mutualistic interaction between Arabidopsis thaliana and Mucor sp. PMID:29615990

  20. Arabidopsis thaliana Ei-5: Minor Vein Architecture Adjustment Compensates for Low Vein Density in Support of Photosynthesis.

    PubMed

    Stewart, Jared J; Polutchko, Stephanie K; Demmig-Adams, Barbara; Adams, William W

    2018-01-01

    An Arabidopsis thaliana accession with naturally low vein density, Eifel-5 (Ei-5), was compared to Columbia-0 (Col-0) with respect to rosette growth, foliar vein architecture, photosynthesis, and transpiration. In addition to having to a lower vein density, Ei-5 grew more slowly, with significantly lower rates of rosette expansion, but had similar capacities for photosynthetic oxygen evolution on a leaf area basis compared to Col-0. The individual foliar minor veins were larger in Ei-5, with a greater number of vascular cells per vein, compared to Col-0. This compensation for low vein density resulted in similar values for the product of vein density × phloem cell number per minor vein in Ei-5 and Col-0, which suggests a similar capacity for foliar sugar export to support similar photosynthetic capacities per unit leaf area. In contrast, the product of vein density × xylem cell number per minor vein was significantly greater in Ei-5 compared to Col-0, and was associated not only with a higher ratio of water-transporting tracheary elements versus sugar-transporting sieve elements but also significantly higher foliar transpiration rates per leaf area in Ei-5. In contrast, previous studies in other systems had reported higher ratios of tracheary to sieve elements and higher transpiration rate to be associated with higher - rather than lower - vein densities. The Ei-5 accession thus further underscores the plasticity of the foliar vasculature by illustrating an example where a higher ratio of tracheary to sieve elements is associated with a lower vein density. Establishment of the Ei-5 accession, with a low vein density but an apparent overcapacity for water flux through the foliar xylem network, may have been facilitated by a higher level of precipitation in its habitat of origin compared to that of the Col-0 accession.

  1. 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.

  2. 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

  3. Blue and green light-induced phototropism in Arabidopsis thaliana and Lactuca sativa L. seedlings

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

    Steinitz, B.; Ren, Z.; Poff, K.L.

    1985-01-01

    Exposure time-response curves for blue and green light-induced phototropic bending in hypocotyls of Arabidopsis thaliana (L.) Heynh. and Lactuca sativa L. seedlings are presented. These seedlings show significant phototropic sensitivity up to 540 to 550 nanometers. Since wavelengths longer than 560 nanometers do not induce phototropic bending, it is suggested that the response to 510 to 550 nanometers light is mediated by the specific blue light photoreceptor of phototropism. The authors advise care in the use of green safelights for studies of phototropism.

  4. Levels of Arabidopsis thaliana Leaf Phosphatidic Acids, Phosphatidylserines, and Most Trienoate-Containing Polar Lipid Molecular Species Increase during the Dark Period of the Diurnal Cycle.

    PubMed

    Maatta, Sara; Scheu, Brad; Roth, Mary R; Tamura, Pamela; Li, Maoyin; Williams, Todd D; Wang, Xuemin; Welti, Ruth

    2012-01-01

    Previous work has demonstrated that plant leaf polar lipid fatty acid composition varies during the diurnal (dark-light) cycle. Fatty acid synthesis occurs primarily during the light, but fatty acid desaturation continues in the absence of light, resulting in polyunsaturated fatty acids reaching their highest levels toward the end of the dark period. In this work, Arabidopsis thaliana were grown at constant (21°C) temperature with 12-h light and 12-h dark periods. Collision induced dissociation time-of-flight mass spectrometry (MS) demonstrated that 16:3 and 18:3 fatty acid content in membrane lipids of leaves are higher at the end of the dark than at the end of the light period, while 16:1, 16:2, 18:0, and 18:1 content are higher at the end of the light period. Lipid profiling of membrane galactolipids, phospholipids, and lysophospholipids by electrospray ionization triple quadrupole MS indicated that the monogalactosyldiacylglycerol, phosphatidylglycerol, and phosphatidylcholine classes include molecular species whose levels are highest at end of the light period and others that are highest at the end of the dark period. The levels of phosphatidic acid (PA) and phosphatidylserine classes were higher at the end of the dark period, and molecular species within these classes either followed the class pattern or were not significantly changed in the diurnal cycle. Phospholipase D (PLD) is a family of enzymes that hydrolyzes phospholipids to produce PA. Analysis of several PLD mutant lines suggests that PLDζ2 and possibly PLDα1 may contribute to diurnal cycling of PA. The polar lipid compositional changes are considered in relation to recent data that demonstrate phosphatidylcholine acyl editing.

  5. The Ca2+ pump inhibitor, thapsigargin, inhibits root gravitropism in Arabidopsis thaliana.

    PubMed

    Urbina, Daniela C; Silva, Herman; Meisel, Lee A

    2006-01-01

    Thapsigargin, a specific inhibitor of most animal intracellular SERCA-type Ca2+ pumps present in the sarcoplasmic/endoplasmic reticulum, was originally isolated from the roots of the Mediterranean plant Thapsia gargancia L. Here, we demonstrate that this root-derived compound is capable of altering root gravitropism in Arabidopsis thaliana. Thapsigargin concentrations as low as 0.1 microM alter root gravitropism whereas under similar conditions cyclopiazonic acid does not. Furthermore, a fluorescently conjugated thapsigargin (BODIPY FL thapsigargin) suggests that target sites for thapsigargin are located in intracellular organelles in the root distal elongation zone and the root cap, regions known to regulate root gravitropism.

  6. Diverse accumulation of several dehydrin-like proteins in cauliflower (Brassica oleracea var. botrytis), Arabidopsis thaliana and yellow lupin (Lupinus luteus) mitochondria under cold and heat stress

    PubMed Central

    2010-01-01

    Background Dehydrins represent hydrophilic proteins acting mainly during cell dehydration and stress response. Dehydrins are generally thermostable; however, the so-called dehydrin-like (dehydrin-related) proteins show variable thermolability. Both groups immunoreact with antibodies directed against the K-segment of dehydrins. Plant mitochondrial dehydrin-like proteins are poorly characterized. The purpose of this study was to extend previous reports on plant dehydrins by comparing the level of immunoprecipitated dehydrin-like proteins in cauliflower (Brassica oleracea var. botrytis), Arabidopsis thaliana and yellow lupin (Lupinus luteus) mitochondria under cold and heat stress. Results All the analyzed plant species showed constitutive accumulation of thermostable mitochondrial putative dehydrins ranging from 50 to 70 kDa. The mitochondrial dehydrin-like proteins observed in cauliflower and Arabidopsis ranged from 10 to 100 kDa and in lupin imbibed seeds and hypocotyls - from 20 to 90 kDa. Cold treatment increased mainly the accumulation of 10-100 kDa cauliflower and Arabidopsis dehydrin-like proteins, in the patterns different in cauliflower leaf and inflorescence mitochondria. However, in lupin mitochondria, cold affected mainly 25-50 kDa proteins and seemed to induce the appearance of some novel dehydrin-like proteins. The influence of frost stress on cauliflower leaf mitochondrial dehydrin- like proteins was less significant. The impact of heat stress was less significant in lupin and Arabidopsis than in cauliflower inflorescence mitochondria. Cauliflower mitochondrial dehydrin-like proteins are localized mostly in the mitochondrial matrix; it seems that some of them may interact with mitochondrial membranes. Conclusions All the results reveal an unexpectedly broad spectrum of dehydrin-like proteins accumulated during some abiotic stress in the mitochondria of the plant species analyzed. They display only limited similarity in size to those reported previously

  7. Madeiran Arabidopsis thaliana Reveals Ancient Long-Range Colonization and Clarifies Demography in Eurasia

    PubMed Central

    Fulgione, Andrea; Koornneef, Maarten; Roux, Fabrice; Hermisson, Joachim; Hancock, Angela M

    2018-01-01

    Abstract The study of model organisms on islands may shed light on rare long-range dispersal events, uncover signatures of local evolutionary processes, and inform demographic inference on the mainland. Here, we sequenced the genomes of Arabidopsis thaliana samples from the oceanic island of Madeira. These samples include the most diverged worldwide, likely a result of long isolation on the island. We infer that colonization of Madeira happened between 70 and 85 ka, consistent with a propagule dispersal model (of size ≥10), or with an ecological window of opportunity. This represents a clear example of a natural long-range dispersal event in A. thaliana. Long-term effective population size on the island, rather than the founder effect, had the greatest impact on levels of diversity, and rates of coalescence. Our results uncover a selective sweep signature on the ancestral haplotype of a known translocation in Eurasia, as well as the possible importance of the low phosphorous availability in volcanic soils, and altitude, in shaping early adaptations to the island conditions. Madeiran genomes, sheltered from the complexities of continental demography, help illuminate ancient demographic events in Eurasia. Our data support a model in which two separate lineages of A. thaliana, one originating in Africa and the other from the Caucasus expanded and met in Iberia, resulting in a secondary contact zone there. Although previous studies inferred that the westward expansion of A. thaliana coincided with the spread of human agriculture, our results suggest that it happened much earlier (20–40 ka). PMID:29216397

  8. The rapidly evolving centromere-specific histone has stringent functional requirements in Arabidopsis thaliana.

    PubMed

    Ravi, Maruthachalam; Kwong, Pak N; Menorca, Ron M G; Valencia, Joel T; Ramahi, Joseph S; Stewart, Jodi L; Tran, Robert K; Sundaresan, Venkatesan; Comai, Luca; Chan, Simon W-L

    2010-10-01

    Centromeres control chromosome inheritance in eukaryotes, yet their DNA structure and primary sequence are hypervariable. Most animals and plants have megabases of tandem repeats at their centromeres, unlike yeast with unique centromere sequences. Centromere function requires the centromere-specific histone CENH3 (CENP-A in human), which replaces histone H3 in centromeric nucleosomes. CENH3 evolves rapidly, particularly in its N-terminal tail domain. A portion of the CENH3 histone-fold domain, the CENP-A targeting domain (CATD), has been previously shown to confer kinetochore localization and centromere function when swapped into human H3. Furthermore, CENP-A in human cells can be functionally replaced by CENH3 from distantly related organisms including Saccharomyces cerevisiae. We have used cenh3-1 (a null mutant in Arabidopsis thaliana) to replace endogenous CENH3 with GFP-tagged variants. A H3.3 tail domain-CENH3 histone-fold domain chimera rescued viability of cenh3-1, but CENH3's lacking a tail domain were nonfunctional. In contrast to human results, H3 containing the A. thaliana CATD cannot complement cenh3-1. GFP-CENH3 from the sister species A. arenosa functionally replaces A. thaliana CENH3. GFP-CENH3 from the close relative Brassica rapa was targeted to centromeres, but did not complement cenh3-1, indicating that kinetochore localization and centromere function can be uncoupled. We conclude that CENH3 function in A. thaliana, an organism with large tandem repeat centromeres, has stringent requirements for functional complementation in mitosis.

  9. Chloroplast behaviour and interactions with other organelles in Arabidopsis thaliana pavement cells.

    PubMed

    Barton, Kiah A; Wozny, Michael R; Mathur, Neeta; Jaipargas, Erica-Ashley; Mathur, Jaideep

    2018-01-29

    Chloroplasts are a characteristic feature of green plants. Mesophyll cells possess the majority of chloroplasts and it is widely believed that, with the exception of guard cells, the epidermal layer in most higher plants does not contain chloroplasts. However, recent observations on Arabidopsis thaliana have shown a population of chloroplasts in pavement cells that are smaller than mesophyll chloroplasts and have a high stroma to grana ratio. Here, using stable transgenic lines expressing fluorescent proteins targeted to the plastid stroma, plasma membrane, endoplasmic reticulum, tonoplast, nucleus, mitochondria, peroxisomes, F-actin and microtubules, we characterize the spatiotemporal relationships between the pavement cell chloroplasts (PCCs) and their subcellular environment. Observations on the PCCs suggest a source-sink relationship between the epidermal and the mesophyll layers, and experiments with the Arabidopsis mutants glabra2 ( gl2 ) and immutans ( im ), which show altered epidermal plastid development, underscored their developmental plasticity. Our findings lay down the foundation for further investigations aimed at understanding the precise role and contributions of PCCs in plant interactions with the environment. © 2018. Published by The Company of Biologists Ltd.

  10. A pivotal role for starch in the reconfiguration of 14C-partitioning and allocation in Arabidopsis thaliana under short-term abiotic stress.

    PubMed

    Dong, Shaoyun; Zhang, Joshua; Beckles, Diane M

    2018-06-18

    Plant carbon status is optimized for normal growth but is affected by abiotic stress. Here, we used 14 C-labeling to provide the first holistic picture of carbon use changes during short-term osmotic, salinity, and cold stress in Arabidopsis thaliana. This could inform on the early mechanisms plants use to survive adverse environment, which is important for efficient agricultural production. We found that carbon allocation from source to sinks, and partitioning into major metabolite pools in the source leaf, sink leaves and roots showed both conserved and divergent responses to the stresses examined. Carbohydrates changed under all abiotic stresses applied; plants re-partitioned 14 C to maintain sugar levels under stress, primarily by reducing 14 C into the storage compounds in the source leaf, and decreasing 14 C into the pools used for growth processes in the roots. Salinity and cold increased 14 C-flux into protein, but as the stress progressed, protein degradation increased to produce amino acids, presumably for osmoprotection. Our work also emphasized that stress regulated the carbon channeled into starch, and its metabolic turnover. These stress-induced changes in starch metabolism and sugar export in the source were partly accompanied by transcriptional alteration in the T6P/SnRK1 regulatory pathway that are normally activated by carbon starvation.

  11. Purification, Crystallization, and Preliminary Crystallographic Analysis of Deoxyuridine Triphosphate Nucleotidohydrolase from Arabidopsis Thaliana

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

    Bajaj,M.; Moriyama, H.

    2007-01-01

    The deoxyuridine triphosphate nucleotidohydrolase gene from Arabidopsis thaliana was expressed and the gene product was purified. Crystallization was performed by the hanging-drop vapour-diffusion method at 298 K using 2 M ammonium sulfate as the precipitant. X-ray diffraction data were collected to 2.2 Angstroms resolution using Cu K{alpha} radiation. The crystal belongs to the orthorhombic space group P212121, with unit-cell parameters a = 69.90, b = 70.86 Angstroms, c = 75.55 Angstroms . Assuming the presence of a trimer in the asymmetric unit, the solvent content was 30%, with a VM of 1.8 Angstroms 3 Da-1.

  12. ARABIDOPSIS THALIANA HOMEOBOX GENE1 establishes the basal boundaries of shoot organs and controls stem growth.

    PubMed

    Gómez-Mena, Concepción; Sablowski, Robert

    2008-08-01

    Apical meristems play a central role in plant development. Self-renewing cells in the central region of the shoot meristem replenish the cell population in the peripheral region, where organ primordia emerge in a predictable pattern, and in the underlying rib meristem, where new stem tissue is formed. While much is known about how organ primordia are initiated and their lateral boundaries established, development at the interface between the stem and the meristem or the lateral organs is poorly understood. Here, we show that the BELL-type ARABIDOPSIS THALIANA HOMEOBOX GENE1 (ATH1) is required for proper development of the boundary between the stem and both vegetative and reproductive organs and that this role partially overlaps with that of CUP-SHAPED COTYLEDON genes. During the vegetative phase, ATH1 also functions redundantly with light-activated genes to inhibit growth of the region below the shoot meristem. Consistent with a role in inhibiting stem growth, ATH1 is downregulated at the start of inflorescence development and ectopic ATH1 expression prevents growth of the inflorescence stem by reducing cell proliferation. Thus, ATH1 modulates growth at the interface between the stem, meristem, and organ primordia and contributes to the compressed vegetative habit of Arabidopsis thaliana.

  13. BoALMT1, an Al-Induced Malate Transporter in Cabbage, Enhances Aluminum Tolerance in Arabidopsis thaliana

    PubMed Central

    Zhang, Lei; Wu, Xin-Xin; Wang, Jinfang; Qi, Chuandong; Wang, Xiaoyun; Wang, Gongle; Li, Mingyue; Li, Xingsheng; Guo, Yang-Dong

    2018-01-01

    Aluminum (Al) is present in approximately 50% of the arable land worldwide and is regarded as the main limiting factor of crop yield on acidic soil. Al-induced root malate efflux plays an important role in the Al tolerance of plants. Here, the aluminum induced malate transporter BoALMT1 (KF322104) was cloned from cabbage (Brassica oleracea). BoALMT1 showed higher expression in roots than in shoots. The expression of BoALMT1 was specifically induced by Al treatment, but not the trivalent cations lanthanum (La), cadmium (Cd), zinc (Zn), or copper (Cu). Subcellular localization studies were performed in onion epidermal cells and revealed that BoALMT1 was localized at the plasma membrane. Scanning Ion-selective Electrode Technique was used to analyze H+ flux. Xenopus oocytes and Arabidopsis thaliana expressing BoALMT1 excreted more H+ under Al treatment. Overexpressing BoALMT1 in transgenic Arabidopsis resulted in enhanced Al tolerance and increased malate secretion. The results suggested that BoALMT1 functions as an Al-resistant gene and encodes a malate transporter. Expressing BoALMT1 in Xenopus oocytes or A. thaliana indicated that BoALMT1 could increase malate secretion and H+ efflux to resist Al tolerance. PMID:29410672

  14. BoALMT1, an Al-Induced Malate Transporter in Cabbage, Enhances Aluminum Tolerance in Arabidopsis thaliana.

    PubMed

    Zhang, Lei; Wu, Xin-Xin; Wang, Jinfang; Qi, Chuandong; Wang, Xiaoyun; Wang, Gongle; Li, Mingyue; Li, Xingsheng; Guo, Yang-Dong

    2017-01-01

    Aluminum (Al) is present in approximately 50% of the arable land worldwide and is regarded as the main limiting factor of crop yield on acidic soil. Al-induced root malate efflux plays an important role in the Al tolerance of plants. Here, the aluminum induced malate transporter BoALMT1 (KF322104) was cloned from cabbage ( Brassica oleracea ). BoALMT1 showed higher expression in roots than in shoots. The expression of BoALMT1 was specifically induced by Al treatment, but not the trivalent cations lanthanum (La), cadmium (Cd), zinc (Zn), or copper (Cu). Subcellular localization studies were performed in onion epidermal cells and revealed that BoALMT1 was localized at the plasma membrane. Scanning Ion-selective Electrode Technique was used to analyze H + flux. Xenopus oocytes and Arabidopsis thaliana expressing BoALMT1 excreted more H + under Al treatment. Overexpressing BoALMT1 in transgenic Arabidopsis resulted in enhanced Al tolerance and increased malate secretion. The results suggested that BoALMT1 functions as an Al-resistant gene and encodes a malate transporter. Expressing BoALMT1 in Xenopus oocytes or A. thaliana indicated that BoALMT1 could increase malate secretion and H+ efflux to resist Al tolerance.

  15. Protists are an integral part of the Arabidopsis thaliana microbiome.

    PubMed

    Sapp, Melanie; Ploch, Sebastian; Fiore-Donno, Anna M; Bonkowski, Michael; Rose, Laura E

    2018-01-01

    Although protists occupy a vast range of habitats and are known to interact with plants among other things via disease suppression, competition or growth stimulation, their contributions to the 'phytobiome' are not well described. To contribute to a more comprehensive picture of the plant holobiont, we examined cercozoan and oomycete taxa living in association with the model plant Arabidopsis thaliana grown in two different soils. Soil, roots, leaves and wooden toothpicks were analysed before and after surface sterilization. Cercozoa were identified using 18S rRNA gene metabarcoding, whereas the Internal Transcribed Spacer 1 was used to determine oomycetes. Subsequent analyses revealed strong spatial structuring of protist communities between compartments, although oomycetes appeared more specialized than Cercozoa. With regards to oomycetes, only members of the Peronosporales and taxa belonging to the genus Globisporangium were identified as shared members of the A. thaliana microbiome. This also applied to cercozoan taxa belonging to the Glissomonadida and Cercomonadida. We identified a strong influence by edaphic factors on the rhizosphere, but not for the phyllosphere. Distinct differences of Cercozoa found preferably in wood or fresh plant material imply specific niche adaptations. Our results highlight the importance of micro-eukaryotes for the plant holobiont. © 2017 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  16. Regulation of Compound Leaf Development in Medicago truncatula by Fused Compound Leaf1, a Class M KNOX Gene[C][W

    PubMed Central

    Peng, Jianling; Yu, Jianbin; Wang, Hongliang; Guo, Yingqing; Li, Guangming; Bai, Guihua; Chen, Rujin

    2011-01-01

    Medicago truncatula is a legume species belonging to the inverted repeat lacking clade (IRLC) with trifoliolate compound leaves. However, the regulatory mechanisms underlying development of trifoliolate leaves in legumes remain largely unknown. Here, we report isolation and characterization of fused compound leaf1 (fcl1) mutants of M. truncatula. Phenotypic analysis suggests that FCL1 plays a positive role in boundary separation and proximal-distal axis development of compound leaves. Map-based cloning indicates that FCL1 encodes a class M KNOX protein that harbors the MEINOX domain but lacks the homeodomain. Yeast two-hybrid assays show that FCL1 interacts with a subset of Arabidopsis thaliana BEL1-like proteins with slightly different substrate specificities from the Arabidopsis homolog KNATM-B. Double mutant analyses with M. truncatula single leaflet1 (sgl1) and palmate-like pentafoliata1 (palm1) leaf mutants show that fcl1 is epistatic to palm1 and sgl1 is epistatic to fcl1 in terms of leaf complexity and that SGL1 and FCL1 act additively and are required for petiole development. Previous studies have shown that the canonical KNOX proteins are not involved in compound leaf development in IRLC legumes. The identification of FCL1 supports the role of a truncated KNOX protein in compound leaf development in M. truncatula. PMID:22080596

  17. GDP-D-mannose epimerase regulates male gametophyte development, plant growth and leaf senescence in Arabidopsis.

    PubMed

    Qi, Tiancong; Liu, Zhipeng; Fan, Meng; Chen, Yan; Tian, Haixia; Wu, Dewei; Gao, Hua; Ren, Chunmei; Song, Susheng; Xie, Daoxin

    2017-09-04

    Plant GDP-D-mannose epimerase (GME) converts GDP-D-mannose to GDP-L-galactose, a precursor of both L-ascorbate (vitamin C) and cell wall polysaccharides. However, the genetic functions of GME in Arabidopsis are unclear. In this study, we found that mutations in Arabidopsis GME affect pollen germination, pollen tube elongation, and transmission and development of the male gametophyte through analysis of the heterozygous GME/gme plants and the homozygous gme plants. Arabidopsis gme mutants also exhibit severe growth defects and early leaf senescence. Surprisingly, the defects in male gametophyte in the gme plants are not restored by L-ascorbate, boric acid or GDP-L-galactose, though boric acid rescues the growth defects of the mutants, indicating that GME may regulate male gametophyte development independent of L-ascorbate and GDP-L-galactose. These results reveal key roles for Arabidopsis GME in reproductive development, vegetative growth and leaf senescence, and suggest that GME regulates plant growth and controls male gametophyte development in different manners.

  18. Enhanced homologous recombination is induced by alpha-particle radiation in somatic cells of Arabidopsis thaliana

    NASA Astrophysics Data System (ADS)

    Bian, Po; Liu, Ping; Wu, Yuejin

    Almost 9 percent of cosmic rays which strike the earth's atmosphere are alpha particles. As one of the ionizing radiations (IR), its biological effects have been widely studied. However, the plant genomic instability induced by alpha-particle radiation was not largely known. In this research, the Arabidopsis thaliana transgenic for GUS recombination substrate was used to evaluate the genomic instability induced by alpha-particle radiation (3.3MeV). The pronounced effects of systemic exposure to alpha-particle radiation on the somatic homologous recombination frequency (HRF) were found at different doses. The 10Gy dose of radiation induced the maximal HRF which was 1.9-fold higher than the control. The local radiation of alpha-particle (10Gy) on root also resulted in a 2.5-fold increase of somatic HRF in non-radiated aerial plant, indicating that the signal(s) of genomic instability was transferred to non-radiated parts and initiated their genomic instability. Concurrent treatment of seedlings of Arabidopsis thaliana with alpha-particle and DMSO(ROS scavenger) both in systemic and local radiation signifi- cantly suppressed the somatic HR, indicating that the free radicals produced by alpha-particle radiation took part in the production of signal of genomic instability rather than the signal transfer. Key words: alpha-particle radiation, somatic homologous recombination, genomic instability

  19. Characterization of adaptation in phototropism of Arabidopsis thaliana

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

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

    1991-02-01

    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 densensitization 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. Basedmore » 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 only vice versa. Both desensitization and enhancement affect only the magnitude of the response and do not affect the fluence threshold.« less

  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. Lipophilic components of the brown seaweed, Ascophyllum nodosum, enhance freezing tolerance in Arabidopsis thaliana.

    PubMed

    Rayirath, Prasanth; Benkel, Bernhard; Mark Hodges, D; Allan-Wojtas, Paula; Mackinnon, Shawna; Critchley, Alan T; Prithiviraj, Balakrishnan

    2009-06-01

    Extracts of the brown seaweed Ascophyllum nodosum enhance plant tolerance against environmental stresses such as drought, salinity, and frost. However, the molecular mechanisms underlying this improved stress tolerance and the nature of the bioactive compounds present in the seaweed extracts that elicits stress tolerance remain largely unknown. We investigated the effect of A. nodosum extracts and its organic sub-fractions on freezing tolerance of Arabidopsis thaliana. Ascophyllum nodosum extracts and its lipophilic fraction significantly increased tolerance to freezing temperatures in in vitro and in vivo assays. Untreated plants exhibited severe chlorosis, tissue damage, and failed to recover from freezing treatments while the extract-treated plants recovered from freezing temperature of -7.5 degrees C in in vitro and -5.5 degrees C in in vivo assays. Electrolyte leakage measurements revealed that the LT(50) value was lowered by 3 degrees C while cell viability staining demonstrated a 30-40% reduction in area of damaged tissue in extract treated plants as compared to water controls. Moreover, histological observations of leaf sections revealed that extracts have a significant effect on maintaining membrane integrity during freezing stress. Treated plants exhibited 70% less chlorophyll damage during freezing recovery as compared to the controls, and this correlated with reduced expression of the chlorphyllase genes AtCHL1 and AtCHL2. Further, the A. nodosum extract treatment modulated the expression of the cold response genes, COR15A, RD29A, and CBF3, resulting in enhanced tolerance to freezing temperatures. More than 2.6-fold increase in expression of RD29A, 1.8-fold increase of CBF3 and two-fold increase in the transcript level of COR15A was observed in plants treated with lipophilic fraction of A. nodosum at -2 degrees C. Taken together, the results suggest that chemical components in A. nodosum extracts protect membrane integrity and affect the expression of

  2. GENE EXPRESSION CHANGES IN ARABIDOPSIS THALIANA SEEDLING ROOTS EXPOSED TO THE MUNITION HEXAHYDRO-1,3,5-TRINITRO-1,3,5-TRIAZINE

    EPA Science Inventory

    Arabidopsis thaliana root transcriptome responses to the munition, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), were assessed using serial analysis of gene expression (SAGE). Comparison of the transcriptional profile for the RDX response to a profile previously described for Ar...

  3. MhYTP1 and MhYTP2 from Apple Confer Tolerance to Multiple Abiotic Stresses in Arabidopsis thaliana

    PubMed Central

    Wang, Na; Guo, Tianli; Wang, Ping; Sun, Xun; Shao, Yun; Jia, Xin; Liang, Bowen; Gong, Xiaoqing; Ma, Fengwang

    2017-01-01

    The first YTH domain-containing RNA binding protein (YTP) was found in rat, where it was related to oxidative stress. Unlike characterizations in yeast and animals, functions of plant YTPs are less clear. Malus hupehensis (Pamp.) Rehd. YTP1 and YTP2 (MhYTP1 and MhYTP2) are known to be active in leaf senescence and fruit ripening. However, no research has been published about their roles in stress responses. Here, we investigate the stress-related functions of MhYTP1 and MhYTP2 in Arabidopsis thaliana. Both of the two genes participated in salicylic acid (SA), jasmonic acid (JA), and abscisic acid (ABA) signaling and play roles in plant responses to oxidative stress, chilling, high temperature, high salinity, and mannitol induced physiological drought stress. Moreover, MhYTP1 plays leading roles in SA and ABA signaling, and MhYTP2 plays leading roles in JA signaling and oxidative stress responses. These results will fill a gap in our knowledge about plant YTPs and stress responses and provide a foundation for future attempts to improve stress tolerance in apple. PMID:28824695

  4. Involvement of STH7 in light-adapted development in Arabidopsis thaliana promoted by both strigolactone and karrikin.

    PubMed

    Thussagunpanit, Jutiporn; Nagai, Yuko; Nagae, Miyu; Mashiguchi, Kiyoshi; Mitsuda, Nobutaka; Ohme-Takagi, Masaru; Nakano, Takeshi; Nakamura, Hidemitsu; Asami, Tadao

    2017-02-01

    Strigolactones (SLs) and karrikins (KARs) regulate photomorphogenesis. GR24, a synthetic SL and KAR 1 , a KAR, inhibit the hypocotyl elongation of Arabidopsis thaliana in a weak light. GR24 and KAR 1 up-regulate the expression of STH7, encoding a transcription factor belonging to the double B-box zinc finger subfamily. In this study, we used STH7-overexpressing (STH7ox) lines and functionally defective STH7 (STH7-SRDX) mutants to investigate roles of SLs and KARs in photomorphogenesis of Arabidopsis. Hypocotyl elongation of STH7-SRDX mutants was less sensitive to both GR24 and KAR 1 treatment than that of wild-type Arabidopsis under weak light conditions. Furthermore, the chlorophyll and anthocyanin content was increased in STH7ox lines when de-etiolated with light and GR24-treated plants had enhanced anthocyanin production. GR24 and KAR 1 treatment significantly increased the expression level of photosynthesis-related genes LHCB1 and rbcS. The results strongly suggest that SL and KAR induce photomorphogenesis of Arabidopsis in an STH7-dependent manner.

  5. A transcriptomic study reveals differentially expressed genes and pathways respond to simulated acid rain in Arabidopsis thaliana.

    PubMed

    Liu, Ting-Wu; Niu, Li; Fu, Bin; Chen, Juan; Wu, Fei-Hua; Chen, Juan; Wang, Wen-Hua; Hu, Wen-Jun; He, Jun-Xian; Zheng, Hai-Lei

    2013-01-01

    Acid rain, as a worldwide environmental issue, can cause serious damage to plants. In this study, we provided the first case study on the systematic responses of arabidopsis (Arabidopsis thaliana (L.) Heynh.) to simulated acid rain (SiAR) by transcriptome approach. Transcriptomic analysis revealed that the expression of a set of genes related to primary metabolisms, including nitrogen, sulfur, amino acid, photosynthesis, and reactive oxygen species metabolism, were altered under SiAR. In addition, transport and signal transduction related pathways, especially calcium-related signaling pathways, were found to play important roles in the response of arabidopsis to SiAR stress. Further, we compared our data set with previously published data sets on arabidopsis transcriptome subjected to various stresses, including wound, salt, light, heavy metal, karrikin, temperature, osmosis, etc. The results showed that many genes were overlapped in several stresses, suggesting that plant response to SiAR is a complex process, which may require the participation of multiple defense-signaling pathways. The results of this study will help us gain further insights into the response mechanisms of plants to acid rain stress.

  6. Transgenic Arabidopsis thaliana containing increased levels of ATP and sucrose is more susceptible to Pseudomonas syringae

    PubMed Central

    Zhang, Renshan; Qi, Hua; Sun, Yuzhe; Xiao, Shi

    2017-01-01

    Disease resistance exerts a fitness cost on plants, presumably due to the extra consumption of energy and carbon. In this study, we examined whether transgenic Arabidopsis thaliana with increased levels of ATP and sucrose is more resistant or susceptible to pathogen infection. Lines of A. thaliana over-expressing purple acid phosphatase 2 (AtPAP2) (OE lines) contain increased levels of ATP and sucrose, with improved growth rate and seed production. Compared to wild type (WT) and pap2 lines, the OE lines were more susceptible to several Pseudomonas syringae pv. tomato (Pst) strains carrying AvrRpm1, AvrRpt2 AvrRps4, AvrPtoB, HrcC and WT strain DC3000. The increased susceptibility of the OE lines to Pst strains cannot solely be attributed to the suppressed expression of R-genes but must also be attributed to the suppression of downstream signaling components, such as MOS2, EDS1 and EDS5. Before infection, the levels of salicylic acid (SA) and jasmonic acid (JA) precursor OPDA were similar in the leaves of OE, pap2 and WT plants, whereas the levels of JA and its derivative JA-Ile were significantly lower in the leaves of OE lines and higher in the pap2 line. The expression of JA marker defense gene PDF1.2 was up-regulated in the OE lines compared to the WT prior to Pst DC3000 infection, but its expression was lower in the OE lines after infection. In summary, high fitness Arabidopsis thaliana exhibited altered JA metabolism and broad suppression of R-genes and downstream genes as well as a higher susceptibility to Pst infections. PMID:28152090

  7. Aseptic Culture Systems of Radopholus similis for In Vitro Assays on Musa spp. and Arabidopsis thaliana

    PubMed Central

    Elsen, A.; Lens, K.; Nguyet, D. T. M.; Broos, S.; Stoffelen, R.; De Waele, D.

    2001-01-01

    Radopholus similis is one of the most damaging nematodes in bananas. Chemical control is currently the most-used method, but nematode control through genetic improvement is widely encouraged. The objective of this study was to establish an aseptic culture system for R. similis and determine whether R. similis can infect and reproduce on in vitro banana plantlets and in vitro Arabidopsis thaliana. In the study's first part, a suitable aseptic culture system was developed using alfalfa callus. Radopholus similis could penetrate and reproduce in the callus. Six weeks after inoculation with 25 females, the reproduction ratio was 26.3 and all vermiform stages were present. The reproduction ratio increased to 223.2 after 12 weeks. Results of a greenhouse test showed that R. similis did not lose its pathogenicity after culturing on alfalfa callus. In the study's second part, the infection and reproduction of the nematodes cultured on the callus were studied on both in vitro banana plantlets and A. thaliana. Radopholus similis infected and reproduced on both banana and A. thaliana. Furthermore, nematode damage was observed in the root systems of both hosts. These successful infections open new perspectives for rapid in vitro screening for resistance in banana cultivars and anti-nematode proteins expressed in A. thaliana. PMID:19266012

  8. Technical advance: stringent control of transgene expression in Arabidopsis thaliana using the Top10 promoter system

    NASA Technical Reports Server (NTRS)

    Love, J.; Scott, A. C.; Thompson, W. F.; Brown, C. S. (Principal Investigator)

    2000-01-01

    We show that the tightly regulated tetracycline-sensitive Top10 promoter system (Weinmann et al. Plant J. 1994, 5, 559-569) is functional in Arabidopsis thaliana. A pure breeding A. thaliana line (JL-tTA/8) was generated which expressed a chimeric fusion of the tetracycline repressor and the activation domain of Herpes simplex virus (tTA), from a single transgenic locus. Plants from this line were crossed with transgenics carrying the ER-targeted green fluorescent protein coding sequence (mGFP5) under control of the Top10 promoter sequence. Progeny from this cross displayed ER-targeted GFP fluorescence throughout the plant, indicating that the tTA-Top10 promoter interaction was functional in A. thaliana. GFP expression was repressed by 100 ng ml-1 tetracycline, an order of magnitude lower than the concentration used previously to repress expression in Nicotiana tabacum. Moreover, the level of GFP expression was controlled by varying the concentration of tetracycline in the medium, allowing a titred regulation of transgenic activity that was previously unavailable in A. thaliana. The kinetics of GFP activity were determined following de-repression of the Top10:mGFP5 transgene, with a visible ER-targeted GFP signal appearing from 24 to 48 h after de-repression.

  9. Altered invertase activities of symptomatic tissues on Beet severe curly top virus (BSCTV) infected Arabidopsis thaliana.

    PubMed

    Park, Jungan; Kim, Soyeon; Choi, Eunseok; Auh, Chung-Kyun; Park, Jong-Bum; Kim, Dong-Giun; Chung, Young-Jae; Lee, Taek-Kyun; Lee, Sukchan

    2013-09-01

    Arabidopsis thaliana infected with Beet severe curly top virus (BSCTV) exhibits systemic symptoms such as stunting of plant growth, callus induction on shoot tips, and curling of leaves and shoot tips. The regulation of sucrose metabolism is essential for obtaining the energy required for viral replication and the development of symptoms in BSCTV-infected A. thaliana. We evaluated the changed transcript level and enzyme activity of invertases in the inflorescence stems of BSCTV-infected A. thaliana. These results were consistent with the increased pattern of ribulose-1,5-bisphosphate carboxylase/oxygenase activity and photosynthetic pigment concentration in virus-infected plants to supply more energy for BSCTV multiplication. The altered gene expression of invertases during symptom development was functionally correlated with the differential expression patterns of D-type cyclins, E2F isoforms, and invertase-related genes. Taken together, our results indicate that sucrose sensing by BSCTV infection may regulate the expression of sucrose metabolism and result in the subsequent development of viral symptoms in relation with activation of cell cycle regulation.

  10. Arsenic Methylation in Arabidopsis thaliana Expressing an Algal Arsenite Methyltransferase Gene Increases Arsenic Phytotoxicity

    PubMed Central

    Tang, Zhong; Lv, Yanling; Chen, Fei; Zhang, Wenwen; Rosen, Barry P.; Zhao, Fang-Jie

    2016-01-01

    Arsenic (As) contamination in soil can lead to elevated transfer of As to the food chain. One potential mitigation strategy is to genetically engineer plants to enable them to transform inorganic As to methylated and volatile As species. In this study, we genetically engineered two ecotypes of Arabidopsis thaliana with the arsenite (As(III)) S-adenosylmethyltransferase (arsM) gene from the eukaryotic alga Chlamydomonas reinhardtii. The transgenic A. thaliana plants gained a strong ability to methylate As, converting most of the inorganic As into dimethylarsenate [DMA(V)] in the shoots. Small amounts of volatile As were detected from the transgenic plants. However, the transgenic plants became more sensitive to As(III) in the medium, suggesting that DMA(V) is more phytotoxic than inorganic As. The study demonstrates a negative consequence of engineered As methylation in plants and points to a need for arsM genes with a strong ability to methylate As to volatile species. PMID:26998776

  11. Roles of miR319 and TCP Transcription Factors in Leaf Development.

    PubMed

    Koyama, Tomotsugu; Sato, Fumihiko; Ohme-Takagi, Masaru

    2017-10-01

    Sophisticated regulation of gene expression, including microRNAs (miRNAs) and their target genes, is required for leaf differentiation, growth, and senescence. The impact of miR319 and its target TEOSINTE BRANCHED1 , CYCLOIDEA , and PROLIFERATING CELL NUCLEAR ANTIGEN BINDING FACTOR ( TCP ) genes on leaf development has been extensively investigated, but the redundancies of these gene families often interfere with the evaluation of their function and regulation in the developmental context. Here, we present the genetic evidence of the involvement of the MIR319 and TCP gene families in Arabidopsis ( Arabidopsis thaliana ) leaf development. Single mutations in MIR319A and MIR319B genes moderately inhibited the formation of leaf serrations, whereas double mutations increased the extent of this inhibition and resulted in the formation of smooth leaves. Mutations in MIR319 and gain-of-function mutations in the TCP4 gene conferred resistance against miR319 and impaired the cotyledon boundary and leaf serration formation. These mutations functionally associated with CUP-SHAPED COTYLEDON genes, which regulate the cotyledon boundary and leaf serration formation. In contrast, loss-of-function mutations in miR319-targeted and nontargeted TCP genes cooperatively induced the formation of serrated leaves in addition to changes in the levels of their downstream gene transcript. Taken together, these findings demonstrate that the MIR319 and TCP gene families underlie robust and multilayer control of leaf development. This study also provides a framework toward future researches on redundant miRNAs and transcription factors in Arabidopsis and crop plants. © 2017 American Society of Plant Biologists. All Rights Reserved.

  12. Intraspecific plant-soil feedback and intraspecific overyielding in Arabidopsis thaliana.

    PubMed

    Bukowski, Alexandra R; Petermann, Jana S

    2014-06-01

    Understanding the mechanisms of community coexistence and ecosystem functioning may help to counteract the current biodiversity loss and its potentially harmful consequences. In recent years, plant-soil feedback that can, for example, be caused by below-ground microorganisms has been suggested to play a role in maintaining plant coexistence and to be a potential driver of the positive relationship between plant diversity and ecosystem functioning. Most of the studies addressing these topics have focused on the species level. However, in addition to interspecific interactions, intraspecific interactions might be important for the structure of natural communities. Here, we examine intraspecific coexistence and intraspecific diversity effects using 10 natural accessions of the model species Arabidopsis thaliana (L.) Heynh. We assessed morphological intraspecific diversity by measuring several above- and below-ground traits. We performed a plant-soil feedback experiment that was based on these trait differences between the accessions in order to determine whether A. thaliana experiences feedback at intraspecific level as a result of trait differences. We also experimentally tested the diversity-productivity relationship at intraspecific level. We found strong differences in above- and below-ground traits between the A. thaliana accessions. Overall, plant-soil feedback occurred at intraspecific level. However, accessions differed in the direction and strength of this feedback: Some accessions grew better on their own soils, some on soils from other accessions. Furthermore, we found positive diversity effects within A. thaliana: Accession mixtures produced a higher total above-ground biomass than accession monocultures. Differences between accessions in their feedback response could not be explained by morphological traits. Therefore, we suggest that they might have been caused by accession-specific accumulated soil communities, by root exudates, or by accession

  13. Intraspecific plant–soil feedback and intraspecific overyielding in Arabidopsis thaliana

    PubMed Central

    Bukowski, Alexandra R; Petermann, Jana S

    2014-01-01

    Understanding the mechanisms of community coexistence and ecosystem functioning may help to counteract the current biodiversity loss and its potentially harmful consequences. In recent years, plant–soil feedback that can, for example, be caused by below-ground microorganisms has been suggested to play a role in maintaining plant coexistence and to be a potential driver of the positive relationship between plant diversity and ecosystem functioning. Most of the studies addressing these topics have focused on the species level. However, in addition to interspecific interactions, intraspecific interactions might be important for the structure of natural communities. Here, we examine intraspecific coexistence and intraspecific diversity effects using 10 natural accessions of the model species Arabidopsis thaliana (L.) Heynh. We assessed morphological intraspecific diversity by measuring several above- and below-ground traits. We performed a plant–soil feedback experiment that was based on these trait differences between the accessions in order to determine whether A. thaliana experiences feedback at intraspecific level as a result of trait differences. We also experimentally tested the diversity–productivity relationship at intraspecific level. We found strong differences in above- and below-ground traits between the A. thaliana accessions. Overall, plant–soil feedback occurred at intraspecific level. However, accessions differed in the direction and strength of this feedback: Some accessions grew better on their own soils, some on soils from other accessions. Furthermore, we found positive diversity effects within A. thaliana: Accession mixtures produced a higher total above-ground biomass than accession monocultures. Differences between accessions in their feedback response could not be explained by morphological traits. Therefore, we suggest that they might have been caused by accession-specific accumulated soil communities, by root exudates, or by accession

  14. ARABIDOPSIS THALIANA HOMEOBOX25 Uncovers a Role for Gibberellins in Seed Longevity1[C][W

    PubMed Central

    Bueso, Eduardo; Muñoz-Bertomeu, Jesús; Campos, Francisco; Brunaud, Veronique; Martínez, Liliam; Sayas, Enric; Ballester, Patricia; Yenush, Lynne; Serrano, Ramón

    2014-01-01

    Seed longevity is crucial for agriculture and plant genetic diversity, but it is limited by cellular damage during storage. Seeds are protected against aging by cellular defenses and by structures such as the seed coat. We have screened an activation-tagging mutant collection of Arabidopsis (Arabidopsis thaliana) and selected four dominant mutants with improved seed longevity (isl1-1D to isl4-1D) under both natural and accelerated aging conditions. In the isl1-1D mutant, characterized in this work, overexpression of the transcription factor ARABIDOPSIS THALIANA HOMEOBOX25 (ATHB25; At5g65410) increases the expression of GIBBERELLIC ACID3-OXIDASE2, encoding a gibberellin (GA) biosynthetic enzyme, and the levels of GA1 and GA4 are higher (3.2- and 1.4-fold, respectively) in the mutant than in the wild type. The morphological and seed longevity phenotypes of the athb25-1D mutant were recapitulated in transgenic plants with moderate (4- to 6-fold) overexpression of ATHB25. Simultaneous knockdown of ATHB25, ATHB22, and ATHB31 expression decreases seed longevity, as does loss of ATHB25 and ATHB22 function in a double mutant line. Seeds from wild-type plants treated with GA and from a quintuple DELLA mutant (with constitutive GA signaling) are more tolerant to aging, providing additional evidence for a role of GA in seed longevity. A correlation was observed in several genotypes between seed longevity and mucilage formation at the seed surface, suggesting that GA may act by reinforcing the seed coat. This mechanism was supported by the observation of a maternal effect in reciprocal crosses between the wild type and the athb25-1D mutant. PMID:24335333

  15. Human Norovirus and Its Surrogates Induce Plant Immune Response in Arabidopsis thaliana and Lactuca sativa.

    PubMed

    Markland, Sarah M; Bais, Harsh; Kniel, Kalmia E

    2017-08-01

    Human norovirus is the leading cause of foodborne illness worldwide with the majority of outbreaks linked to fresh produce and leafy greens. It is essential that we thoroughly understand the type of relationship and interactions that take place between plants and human norovirus to better utilize control strategies to reduce transmission of norovirus in the field onto plants harvested for human consumption. In this study the expression of gene markers for the salicylic acid (SA) and jasmonic acid (JA) plant defense pathways was measured and compared in romaine lettuce (Lactuca sativa) and Arabidopsis thaliana Col-0 plants that were inoculated with Murine Norovirus-1, Tulane Virus, human norovirus GII.4, or Hank's Balanced Salt Solution (control). Genes involving both the SA and JA pathways were expressed in both romaine lettuce and A. thaliana for all three viruses, as well as controls. Studies, including gene expression of SA- and JA-deficient A. thaliana mutant lines, suggest that the JA pathway is more likely involved in the plant immune response to human norovirus. This research provides the first pieces of information regarding how foodborne viruses interact with plants in the preharvest environment.

  16. Arabidopsis thaliana as a suitable model host for research on interactions between plant and foliar nematodes, parasites of plant shoot.

    PubMed

    Wang, Dong-Wei; Peng, Xiao-Fang; Xie, Hui; Xu, Chun-Ling; Cheng, De-Qiang; Li, Jun-Yi; Wu, Wen-Jia; Wang, Ke

    2016-12-02

    The rice white tip nematode (RWTN), Aphelenchoides besseyi and the chrysanthemum foliar nematode (CFN), Aphelenchoides ritzemabosi are migratory plant parasitic nematodes that infect the aboveground parts of plants. In this research, Arabidopsis thaliana was infected by RWTN and CFN under indoor aseptic cultivation, and the nematodes caused recognizable symptoms in the leaves. Furthermore, RWTN and CFN completed their life cycles and proliferated. Therefore, A. thaliana was identified as a new host of RWTN and CFN. The optimum inoculum concentration for RWTN and CFN was 100 nematodes/plantlet, and the optimum inoculum times were 21 and 24 days, respectively. For different RWTN populations, the pathogenicity and reproduction rates were different in the A. thaliana Col-0 ecotype and were positively correlated. The optimum A. thaliana ecotypes were Col-0 and WS, which were the most susceptible to RWTN and CFN, respectively. Additionally, RWTN was ectoparasitic and CFN was ecto- and endoparasitic in A. thaliana. The RWTN and CFN migrated from inoculated leaves to the entire plantlet, and the number of nematodes in different parts of A. thaliana was not correlated with distance from the inoculum point. This is a detailed study of the behavior and infection process of foliar nematodes on A. thaliana.

  17. Different mechanisms for Arabidopsis thaliana hybrid necrosis cases inferred from temperature responses.

    PubMed

    Muralidharan, S; Box, M S; Sedivy, E L; Wigge, P A; Weigel, D; Rowan, B A

    2014-11-01

    Temperature is a major determinant of plant growth, development and success. Understanding how plants respond to temperature is particularly relevant in a warming climate. Plant immune responses are often suppressed above species-specific critical temperatures. This is also true for intraspecific hybrids of Arabidopsis thaliana that express hybrid necrosis due to inappropriate activation of the immune system caused by epistatic interactions between alleles from different genomes. The relationship between temperature and defence is unclear, largely due to a lack of studies that assess immune activation over a wide range of temperatures. To test whether the temperature-based suppression of ectopic immune activation in hybrids exhibits a linear or non-linear relationship, we characterised the molecular and morphological phenotypes of two different necrotic A. thaliana hybrids over a range of ecologically relevant temperatures. We found both linear and non-linear responses for expression of immunity markers and for morphological defects depending on the underlying genetic cause. This suggests that the influence of temperature on the trade-off between immunity and growth depends on the specific defence components involved. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

  18. Gravitropism in Arabidopsis thaliana: violation of the sine- and resultant-law

    NASA Astrophysics Data System (ADS)

    Galland, Paul

    We investigated the gravitropic bending of hypocotyls and roots of seedlings of Arabidopsis tha-liana in response to long-term centrifugal accelerations in a range of 5 x 10-3 to 4 x g. The so-cal-led resultant law of gravitropism, a corollary of the so called sine law, claims that during centri-fugation a gravitropic organ aligns itself parallel to the resultant stimulus vector. We show here that neither of the two empirical “laws” is apt to describe the complex gravitropic behaviour of seedlings of Arabidopsis. Hypocotyls obey reasonably well the resultant law while roots display a complex behaviour that is clearly at variance with it. Horizontally centrifuged seedlings sense minute accelerations acting parallel to the longitudinal axis. If the centrifugal vector points to-ward the cotyledons, then the bending of hypocotyls and roots is greatly enhanced. If the centri-fugal vector points, however, toward the root tip, then only the bending of roots is enhanced by accelerations as low as 5 x 10-3 x g (positive tonic effect). The absolute gravitropic thresholds were determined for hypocotyls and roots in a clinostat-centrifuge and found to be near 1.5 x 10-2 x g. A behavioural mutant, ehb1-2 (Knauer et al. 2011), displays a lower gravitropic threshold for roots, not however, for hypocotyls. The complex gravitropic behaviour of seedlings of Arabi-dopsis is at odds with the classical sine- as well as the resultant law and can indicates the eminent role that is played by the acceleration vector operating longitudinally to the seedling axis.

  19. Interstitial telomere-like repeats in the Arabidopsis thaliana genome.

    PubMed

    Uchida, Wakana; Matsunaga, Sachihiro; Sugiyama, Ryuji; Kawano, Shigeyuki

    2002-02-01

    Eukaryotic chromosomal ends are protected by telomeres, which are thought to play an important role in ensuring the complete replication of chromosomes. On the other hand, non-functional telomere-like repeats in the interchromosomal regions (interstitial telomeric repeats; ITRs) have been reported in several eukaryotes. In this study, we identified eight ITRs in the Arabidopsis thaliana genome, each consisting of complete and degenerate 300- to 1200-bp sequences. The ITRs were grouped into three classes (class IA-B, class II, and class IIIA-E) based on the degeneracy of the telomeric repeats in ITRs. The telomeric repeats of the two ITRs in class I were conserved for the most part, whereas the single ITR in class II, and the five ITRs in class III were relatively degenerated. In addition, degenerate ITRs were surrounded by common sequences that shared 70-100% homology to each other; these are named ITR-adjacent sequences (IAS). Although the genomic regions around ITRs in class I lacked IAS, those around ITRs in class II contained IAS (IASa), and those around five ITRs in class III had nine types of IAS (IASb, c, d, e, f, g, h, i, and j). Ten IAS types in classes II and III showed no significant homology to each other. The chromosomal locations of ITRs and IAS were not category-related, but most of them were adjacent to, or part of, a centromere. These results show that the A. thaliana genome has undergone chromosomal rearrangements, such as end-fusions and segmental duplications.

  20. Reference-guided assembly of four diverse Arabidopsis thaliana genomes

    PubMed Central

    Schneeberger, Korbinian; Ossowski, Stephan; Ott, Felix; Klein, Juliane D.; Wang, Xi; Lanz, Christa; Smith, Lisa M.; Cao, Jun; Fitz, Joffrey; Warthmann, Norman; Henz, Stefan R.; Huson, Daniel H.; Weigel, Detlef

    2011-01-01

    We present whole-genome assemblies of four divergent Arabidopsis thaliana strains that complement the 125-Mb reference genome sequence released a decade ago. Using a newly developed reference-guided approach, we assembled large contigs from 9 to 42 Gb of Illumina short-read data from the Landsberg erecta (Ler-1), C24, Bur-0, and Kro-0 strains, which have been sequenced as part of the 1,001 Genomes Project for this species. Using alignments against the reference sequence, we first reduced the complexity of the de novo assembly and later integrated reads without similarity to the reference sequence. As an example, half of the noncentromeric C24 genome was covered by scaffolds that are longer than 260 kb, with a maximum of 2.2 Mb. Moreover, over 96% of the reference genome was covered by the reference-guided assembly, compared with only 87% with a complete de novo assembly. Comparisons with 2 Mb of dideoxy sequence reveal that the per-base error rate of the reference-guided assemblies was below 1 in 10,000. Our assemblies provide a detailed, genomewide picture of large-scale differences between A. thaliana individuals, most of which are difficult to access with alignment-consensus methods only. We demonstrate their practical relevance in studying the expression differences of polymorphic genes and show how the analysis of sRNA sequencing data can lead to erroneous conclusions if aligned against the reference genome alone. Genome assemblies, raw reads, and further information are accessible through http://1001genomes.org/projects/assemblies.html. PMID:21646520

  1. Inducible repression of multiple expansin genes leads to growth suppression during leaf development.

    PubMed

    Goh, Hoe-Han; Sloan, Jennifer; Dorca-Fornell, Carmen; Fleming, Andrew

    2012-08-01

    Expansins are cell wall proteins implicated in the control of plant growth via loosening of the extracellular matrix. They are encoded by a large gene family, and data linked to loss of single gene function to support a role of expansins in leaf growth remain limited. Here, we provide a quantitative growth analysis of transgenics containing an inducible artificial microRNA construct designed to down-regulate the expression of a number of expansin genes that an expression analysis indicated are expressed during the development of Arabidopsis (Arabidopsis thaliana) leaf 6. The results support the hypothesis that expansins are required for leaf growth and show that decreased expansin gene expression leads to a more marked repression of growth during the later stage of leaf development. In addition, a histological analysis of leaves in which expansin gene expression was suppressed indicates that, despite smaller leaves, mean cell size was increased. These data provide functional evidence for a role of expansins in leaf growth, indicate the importance of tissue/organ developmental context for the outcome of altered expansin gene expression, and highlight the separation of the outcome of expansin gene expression at the cellular and organ levels.

  2. A novel role for methyl cysteinate, a cysteine derivative, in cesium accumulation in Arabidopsis thaliana

    PubMed Central

    Adams, Eri; Miyazaki, Takae; Hayaishi-Satoh, Aya; Han, Minwoo; Kusano, Miyako; Khandelia, Himanshu; Saito, Kazuki; Shin, Ryoung

    2017-01-01

    Phytoaccumulation is a technique to extract metals from soil utilising ability of plants. Cesium is a valuable metal while radioactive isotopes of cesium can be hazardous. In order to establish a more efficient phytoaccumulation system, small molecules which promote plants to accumulate cesium were investigated. Through chemical library screening, 14 chemicals were isolated as ‘cesium accumulators’ in Arabidopsis thaliana. Of those, methyl cysteinate, a derivative of cysteine, was found to function within the plant to accumulate externally supplemented cesium. Moreover, metabolite profiling demonstrated that cesium treatment increased cysteine levels in Arabidopsis. The cesium accumulation effect was not observed for other cysteine derivatives or amino acids on the cysteine metabolic pathway tested. Our results suggest that methyl cysteinate, potentially metabolised from cysteine, binds with cesium on the surface of the roots or inside plant cells and improve phytoaccumulation. PMID:28230101

  3. Madeiran Arabidopsis thaliana reveals ancient long-range colonization and clarifies demography in Eurasia.

    PubMed

    Fulgione, Andrea; Koornneef, Maarten; Roux, Fabrice; Hermisson, Joachim; Hancock, Angela M

    2017-12-05

    The study of model organisms on islands may shed light on rare long-range dispersal events, uncover signatures of local evolutionary processes, and inform demographic inference on the mainland. Here, we sequenced the genomes of Arabidopsis thaliana samples from the oceanic island of Madeira. These samples include the most diverged worldwide, likely a result of long isolation on the island. We infer that colonisation of Madeira happened between 70 and 85 kya, consistent with a propagule dispersal model (of size > =10), or with an ecological window of opportunity. This represents a clear example of a natural long-range dispersal event in A. thaliana. Long-term effective population size on the island, rather than the founder effect, had the greatest impact on levels of diversity, and rates of coalescence. Our results uncover a selective sweep signature on the ancestral haplotype of a known translocation in Eurasia, as well as the possible importance of the low phosphorous availability in volcanic soils, and altitude, in shaping early adaptations to the island conditions. Madeiran genomes, sheltered from the complexities of continental demography, help illuminate ancient demographic events in Eurasia. Our data support a model in which two separate lineages of A. thaliana, one originating in Africa and the other from the Caucasus expanded and met in Iberia, resulting in a secondary contact zone there. While previous studies inferred that the westward expansion of A. thaliana coincided with the spread of human agriculture, our results suggest it happened much earlier (20-40 kya). © The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  4. Blue and Green Light-Induced Phototropism in Arabidopsis thaliana and Lactuca sativa L. Seedlings 1

    PubMed Central

    Steinitz, Benjamin; Ren, Zhangling; Poff, Kenneth L.

    1985-01-01

    Exposure time-response curves for blue and green light-induced phototropic bending in hypocotyls of Arabidopsis thaliana (L.) Heynh. and Lactuca sativa L. seedlings are presented. These seedlings show significant phototropic sensitivity up to 540 to 550 nanometers. Since wave-lengths longer than 560 nanometers do not induce phototropic bending, it is suggested that the response to 510 to 550 nanometers light is mediated by the specific blue light photoreceptor of phototropism. We advise care in the use of green `safelights' for studies of phototropism. PMID:16664021

  5. Fertilization-independent seed development in Arabidopsis thaliana.

    PubMed

    Chaudhury, A M; Ming, L; Miller, C; Craig, S; Dennis, E S; Peacock, W J

    1997-04-15

    We report mutants in Arabidopsis thaliana (fertilization-independent seed:fis) in which certain processes of seed development are uncoupled from the double fertilization event that occurs after pollination. These mutants were isolated as ethyl methanesulfonate-induced pseudo-revertants of the pistillata phenotype. Although the pistillata (pi) mutant has short siliques devoid of seed, the fis mutants in the pi background have long siliques containing developing seeds, even though the flowers remain free of pollen. The three fis mutations map to loci on three different chromosomes. In fis1 and fis2 seeds, the autonomous endosperm nuclei are diploid and the endosperm develops to the point of cellularization; the partially developed seeds then atrophy. In these two mutants, proembryos are formed in a low proportion of seeds and do not develop beyond the globular stage. When FIS/fis plants are pollinated by pollen from FIS/FIS plants, approximately 50% of the resulting seeds contain fully developed embryos; these seeds germinate and form viable seedlings (FIS/FIS). The other 50% of seeds shrivel and do not germinate; they contain embryos arrested at the torpedo stage (FIS/fis). In normal sexual reproduction, the products of the FIS genes are likely to play important regulatory roles in the development of seed after fertilization.

  6. 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

  7. High Concentration of Melatonin Regulates Leaf Development by Suppressing Cell Proliferation and Endoreduplication in Arabidopsis.

    PubMed

    Wang, Qiannan; An, Bang; Shi, Haitao; Luo, Hongli; He, Chaozu

    2017-05-05

    N -acetyl-5-methoxytryptamine (Melatonin), as a crucial messenger in plants, functions in adjusting biological rhythms, stress tolerance, plant growth and development. Several studies have shown the retardation effect of exogenous melatonin treatment on plant growth and development. However, the in vivo role of melatonin in regulating plant leaf growth and the underlying mechanism are still unclear. In this study, we found that high concentration of melatonin suppressed leaf growth in Arabidopsis by reducing both cell size and cell number. Further kinetic analysis of the fifth leaves showed that melatonin remarkably inhibited cell division rate. Additionally, flow cytometic analysis indicated that melatonin negatively regulated endoreduplication during leaf development. Consistently, the expression analysis revealed that melatonin regulated the transcriptional levels of key genes of cell cycle and ribosome. Taken together, this study suggests that high concentration of melatonin negatively regulated the leaf growth and development in Arabidopsis , through modulation of endoreduplication and the transcripts of cell cycle and ribosomal key genes.

  8. High Concentration of Melatonin Regulates Leaf Development by Suppressing Cell Proliferation and Endoreduplication in Arabidopsis

    PubMed Central

    Wang, Qiannan; An, Bang; Shi, Haitao; Luo, Hongli; He, Chaozu

    2017-01-01

    N-acetyl-5-methoxytryptamine (Melatonin), as a crucial messenger in plants, functions in adjusting biological rhythms, stress tolerance, plant growth and development. Several studies have shown the retardation effect of exogenous melatonin treatment on plant growth and development. However, the in vivo role of melatonin in regulating plant leaf growth and the underlying mechanism are still unclear. In this study, we found that high concentration of melatonin suppressed leaf growth in Arabidopsis by reducing both cell size and cell number. Further kinetic analysis of the fifth leaves showed that melatonin remarkably inhibited cell division rate. Additionally, flow cytometic analysis indicated that melatonin negatively regulated endoreduplication during leaf development. Consistently, the expression analysis revealed that melatonin regulated the transcriptional levels of key genes of cell cycle and ribosome. Taken together, this study suggests that high concentration of melatonin negatively regulated the leaf growth and development in Arabidopsis, through modulation of endoreduplication and the transcripts of cell cycle and ribosomal key genes. PMID:28475148

  9. Variation in seed dormancy quantitative trait loci in Arabidopsis thaliana originating from one site.

    PubMed

    Silady, Rebecca A; Effgen, Sigi; Koornneef, Maarten; Reymond, Matthieu

    2011-01-01

    A Quantitative Trait Locus (QTL) analysis was performed using two novel Recombinant Inbred Line (RIL) populations, derived from the progeny between two Arabidopsis thaliana genotypes collected at the same site in Kyoto (Japan) crossed with the reference laboratory strain Landsberg erecta (Ler). We used these two RIL populations to determine the genetic basis of seed dormancy and flowering time, which are assumed to be the main traits controlling life history variation in Arabidopsis. The analysis revealed quantitative variation for seed dormancy that is associated with allelic variation at the seed dormancy QTL DOG1 (for Delay Of Germination 1) in one population and at DOG6 in both. These DOG QTL have been previously identified using mapping populations derived from accessions collected at different sites around the world. Genetic variation within a population may enhance its ability to respond accurately to variation within and between seasons. In contrast, variation for flowering time, which also segregated within each mapping population, is mainly governed by the same QTL.

  10. Transcriptomic Profiling Analysis of Arabidopsis thaliana Treated with Exogenous Myo-Inositol

    PubMed Central

    Ye, Wenxing; Ren, Weibo; Kong, Lingqi; Zhang, Wanjun; Wang, Tao

    2016-01-01

    Myo-insositol (MI) is a crucial substance in the growth and developmental processes in plants. It is commonly added to the culture medium to promote adventitious shoot development. In our previous work, MI was found in influencing Agrobacterium-mediated transformation. In this report, a high-throughput RNA sequencing technique (RNA-Seq) was used to investigate differently expressed genes in one-month-old Arabidopsis seedling grown on MI free or MI supplemented culture medium. The results showed that 21,288 and 21,299 genes were detected with and without MI treatment, respectively. The detected genes included 184 new genes that were not annotated in the Arabidopsis thaliana reference genome. Additionally, 183 differentially expressed genes were identified (DEGs, FDR ≤0.05, log2 FC≥1), including 93 up-regulated genes and 90 down-regulated genes. The DEGs were involved in multiple pathways, such as cell wall biosynthesis, biotic and abiotic stress response, chromosome modification, and substrate transportation. Some significantly differently expressed genes provided us with valuable information for exploring the functions of exogenous MI. RNA-Seq results showed that exogenous MI could alter gene expression and signaling transduction in plant cells. These results provided a systematic understanding of the functions of exogenous MI in detail and provided a foundation for future studies. PMID:27603208

  11. Functional variation in a disease resistance gene in populations of Arabidopsis thaliana.

    PubMed

    Jorgensen, T H; Emerson, B C

    2008-11-01

    Analyses of functional genetic diversity in natural populations may provide important new insights into gene function and are necessary to understand the evolutionary processes maintaining diversity itself. The importance of including diversity within and between local populations in such studies is often ignored although many of the processes affecting genetic diversity act on this scale. Here we examine the molecular diversity in RPW8 (Recognition of Powdery Mildew), a gene conferring broad-spectrum resistance to powdery mildews in Arabidopsis thaliana stock-center accessions. Our eight UK study populations of the weedy A. thaliana were from locations judged to be subject to a minimum of anthropogenic disturbance and potentially long established. The majority of populations comprised considerable variation both in disease phenotype and RPW8 genotype. Although resistant individuals shared a major RPW8 genotype, no single allele was uniquely associated with resistance. It is concluded that RPW8 is an essential component of resistance to powdery mildews in A. thaliana, but not the only genetic factor involved in this process. No signature of selection was detected at RPW8 with a microsatellite multilocus test using an empirical null model. Unlike many previous studies of this model plant species, we found high levels of genetic diversity and relatively low differentiation (F(ST) = 0.31) between populations at 14 microsatellite markers. This is judged to be due to our sampling being aimed at potentially long established populations and highlights the importance of population choice for studies of genetic diversity within this species.

  12. Chromatin Immunoprecipitation Sequencing (ChIP-Seq) for Transcription Factors and Chromatin Factors in Arabidopsis thaliana Roots: From Material Collection to Data Analysis.

    PubMed

    Cortijo, Sandra; Charoensawan, Varodom; Roudier, François; Wigge, Philip A

    2018-01-01

    Chromatin immunoprecipitation combined with next-generation sequencing (ChIP-seq) is a powerful technique to investigate in vivo transcription factor (TF) binding to DNA, as well as chromatin marks. Here we provide a detailed protocol for all the key steps to perform ChIP-seq in Arabidopsis thaliana roots, also working on other A. thaliana tissues and in most non-ligneous plants. We detail all steps from material collection, fixation, chromatin preparation, immunoprecipitation, library preparation, and finally computational analysis based on a combination of publicly available tools.

  13. ARACNe-based inference, using curated microarray data, of Arabidopsis thaliana root transcriptional regulatory networks

    PubMed Central

    2014-01-01

    Background Uncovering the complex transcriptional regulatory networks (TRNs) that underlie plant and animal development remains a challenge. However, a vast amount of data from public microarray experiments is available, which can be subject to inference algorithms in order to recover reliable TRN architectures. Results In this study we present a simple bioinformatics methodology that uses public, carefully curated microarray data and the mutual information algorithm ARACNe in order to obtain a database of transcriptional interactions. We used data from Arabidopsis thaliana root samples to show that the transcriptional regulatory networks derived from this database successfully recover previously identified root transcriptional modules and to propose new transcription factors for the SHORT ROOT/SCARECROW and PLETHORA pathways. We further show that these networks are a powerful tool to integrate and analyze high-throughput expression data, as exemplified by our analysis of a SHORT ROOT induction time-course microarray dataset, and are a reliable source for the prediction of novel root gene functions. In particular, we used our database to predict novel genes involved in root secondary cell-wall synthesis and identified the MADS-box TF XAL1/AGL12 as an unexpected participant in this process. Conclusions This study demonstrates that network inference using carefully curated microarray data yields reliable TRN architectures. In contrast to previous efforts to obtain root TRNs, that have focused on particular functional modules or tissues, our root transcriptional interactions provide an overview of the transcriptional pathways present in Arabidopsis thaliana roots and will likely yield a plethora of novel hypotheses to be tested experimentally. PMID:24739361

  14. Characterization of the Sucrose Phosphate Phosphatase (SPP) Isoforms from Arabidopsis thaliana and Role of the S6PPc Domain in Dimerization.

    PubMed

    Albi, Tomás; Ruiz, M Teresa; de Los Reyes, Pedro; Valverde, Federico; Romero, José M

    2016-01-01

    Sucrose-phosphate phosphatase (SPP) catalyses the final step in the sucrose biosynthesis pathway. Arabidopsis thaliana genome codifies four SPP isoforms. In this study, the four Arabidopsis thaliana genes coding for SPP isoforms have been cloned, expressed in Escherichia coli and the kinetic and regulatory properties of the purified enzymes analysed. SPP2 is the isoform showing the highest activity, with SPP3b and SPP3a showing lower activity levels. No activity was detected for SPP1. We propose that this lack of activity is probably due to the absence of an essential amino acid participating in catalysis and/or in the binding of the substrate, sucrose-6-phosphate (Suc6P). The expression patterns of Arabidopsis SPP genes indicate that SPP2 and SPP3b are the main isoforms expressed in different tissues and organs, although the non-catalytic SPP1 is the main isoform expressed in roots. Thus, SPP1 could have acquired new unknown functions. We also show that the three catalytically active SPPs from Arabidopsis are dimers. By generating a chimeric SPP composed of the monomeric cyanobacterial SPP fused to the higher plant non-catalytic S6PPc domain (from SPP2), we show that the S6PPc domain is responsible for SPP dimerization. This is the first experimental study on the functionality and gene expression pattern of all the SPPs from a single plant species.

  15. Light, genotype, and abscisic acid affect chloroplast positioning in guard cells of Arabidopsis thaliana leaves in distinct ways.

    PubMed

    Königer, Martina; Jessen, Brita; Yang, Rui; Sittler, Dorothea; Harris, Gary C

    2010-09-01

    The goal of this study was to investigate the effects of light intensity, genotype, and various chemical treatments on chloroplast movement in guard cells of Arabidopsis thaliana leaves. After treatment at various light intensities (dark, low, and high light), leaf discs were fixed with glutaraldehyde, and imaged using confocal laser microscopy. Each chloroplast was assigned a horizontal (close to pore, center, or epidermal side) and vertical (outer, middle, inner) position. White light had a distinct effect on chloroplast positioning, most notably under high light (HL) when chloroplasts on the upper leaf surface of wild-type (WT) moved from epidermal and center positions toward the pore. This was not the case for phot1-5/phot2-1 or phot2-1 plants, thus phototropins are essential for chloroplast positioning in guard cells. In npq1-2 mutants, fewer chloroplasts moved to the pore position under HL than in WT plants, indicating that white light can affect chloroplast positioning also in a zeaxanthin-dependent way. Cytochalasin B inhibited the movement of chloroplasts to the pore under HL, while oryzalin did not, supporting the idea that actin plays a role in the movement. The movement along actin cables is dependent on CHUP1 since chloroplast positioning in chup1 was significantly altered. Abscisic acid (ABA) caused most chloroplasts in WT and phot1-5/phot2-1 to be localized in the center, middle part of the guard cells irrespective of light treatment. This indicates that not only light but also water stress influences chloroplast positioning.

  16. The poetry of reproduction: the role of LEAFY in Arabidopsis thaliana flower formation.

    PubMed

    Siriwardana, Nirodhini S; Lamb, Rebecca S

    2012-01-01

    For successful reproduction, angiosperms must form fertile flowers at the appropriate positions and at the appropriate times. The reproductive transition is especially important for monocarpic plants that only flower once. In the model annual plant Arabidopsis thaliana, this transition is controlled through regulation of a group of genes termed floral meristem identity genes, of which LEAFY (LFY) is arguably the most important. LFY orthologs are found throughout land plants and are essential for angiosperm reproduction. These genes have also been implicated in reproductive development in gymnosperms. LFY encodes a plant-specific transcription factor that can act as either an activator or repressor depending on context, including what co-factors it is interacting with. It controls multiple aspects of floral morphogenesis, including phyllotaxis, organ number, organ identity and determinacy. Much progress has been made in elucidating the molecular mechanisms through which LFY and its orthologs contribute to a precise switch to flowering. We discuss the current state of knowledge in Arabidopsis, with an emphasis on known target genes and co-factors of LFY.

  17. Cloning and kinetic characterization of Arabidopsis thaliana solanesyl diphosphate synthase.

    PubMed

    Hirooka, Kazutake; Bamba, Takeshi; Fukusaki, Ei-ichiro; Kobayashi, Akio

    2003-03-01

    trans -Long-chain prenyl diphosphate synthases catalyse the sequential condensation of isopentenyl diphosphate (C(5)) units with allylic diphosphate to produce the C(30)-C(50) prenyl diphosphates, which are precursors of the side chains of prenylquinones. Based on the relationship between product specificity and the region around the first aspartate-rich motif in trans -prenyl diphosphate synthases characterized so far, we have isolated the cDNA for a member of trans -long-chain prenyl diphosphate synthases from Arabidopsis thaliana. The cDNA was heterologously expressed in Escherichia coli, and the recombinant His(6)-tagged protein was purified and characterized. Product analysis revealed that the cDNA encodes solanesyl diphosphate (C(45)) synthase (At-SPS). At-SPS utilized farnesyl diphosphate (FPP; C(15)) and geranylgeranyl diphosphate (GGPP; C(20)), but did not accept either the C(5) or the C(10) allylic diphosphate as a primer substrate. The Michaelis constants for FPP and GGPP were 5.73 microM and 1.61 microM respectively. We also performed an analysis of the side chains of prenylquinones extracted from the A. thaliana plant, and showed that its major prenylquinones, i.e. plastoquinone and ubiquinone, contain the C(45) prenyl moiety. This suggests that At-SPS might be devoted to the biosynthesis of either or both of the prenylquinone side chains. This is the first established trans -long-chain prenyl diphosphate synthase from a multicellular organism.

  18. 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.

  19. Neutralization of Bacterial YoeBSpn Toxicity and Enhanced Plant Growth in Arabidopsis thaliana via Co-Expression of the Toxin-Antitoxin Genes

    PubMed Central

    Abu Bakar, Fauziah; Yeo, Chew Chieng; Harikrishna, Jennifer Ann

    2016-01-01

    Bacterial toxin-antitoxin (TA) systems have various cellular functions, including as part of the general stress response. The genome of the Gram-positive human pathogen Streptococcus pneumoniae harbors several putative TA systems, including yefM-yoeBSpn, which is one of four systems that had been demonstrated to be biologically functional. Overexpression of the yoeBSpn toxin gene resulted in cell stasis and eventually cell death in its native host, as well as in Escherichia coli. Our previous work showed that induced expression of a yoeBSpn toxin-Green Fluorescent Protein (GFP) fusion gene apparently triggered apoptosis and was lethal in the model plant, Arabidopsis thaliana. In this study, we investigated the effects of co-expression of the yefMSpn antitoxin and yoeBSpn toxin-GFP fusion in transgenic A. thaliana. When co-expressed in Arabidopsis, the YefMSpn antitoxin was found to neutralize the toxicity of YoeBSpn-GFP. Interestingly, the inducible expression of both yefMSpn antitoxin and yoeBSpn toxin-GFP fusion in transgenic hybrid Arabidopsis resulted in larger rosette leaves and taller plants with a higher number of inflorescence stems and increased silique production. To our knowledge, this is the first demonstration of a prokaryotic antitoxin neutralizing its cognate toxin in plant cells. PMID:27104531

  20. Composition of secondary alcohols, ketones, alkanediols, and ketols in Arabidopsis thaliana cuticular waxes

    PubMed Central

    Wen, Miao; Jetter, Reinhard

    2009-01-01

    Arabidopsis wax components containing secondary functional groups were examined (i) to test the biosynthetic relationship between secondary alcohols and ketols and (ii) to determine the regiospecificity and substrate preference of the enzyme involved in ketol biosynthesis. The stem wax of Arabidopsis wild type contained homologous series of C27 to C31 secondary alcohols (2.4 μg cm−2) and C28 to C30 ketones (6.0 μg cm−2) dominated by C29 homologues. In addition, compound classes containing two secondary functional groups were identified as C29 diols (∼0.05 μg cm−2) and ketols (∼0.16 μg cm−2). All four compound classes showed characteristic isomer distributions, with functional groups located between C-14 and C-16. In the mah1 mutant stem wax, diols and ketols could not be detected, while the amounts of secondary alcohols and ketones were drastically reduced. In two MAH1-overexpressing lines, equal amounts of C29 and C31 secondary alcohols were detected. Based on the comparison of homologue and isomer compositions between the different genotypes, it can be concluded that biosynthetic pathways lead from alkanes to secondary alcohols, and via ketones or diols to ketols. It seems plausible that MAH1 is the hydroxylase enzyme involved in all these conversions in Arabidopsis thaliana. PMID:19346242

  1. Control of leaf expansion: a developmental switch from metabolics to hydraulics.

    PubMed

    Pantin, Florent; Simonneau, Thierry; Rolland, Gaëlle; Dauzat, Myriam; Muller, Bertrand

    2011-06-01

    Leaf expansion is the central process by which plants colonize space, allowing energy capture and carbon acquisition. Water and carbon emerge as main limiting factors of leaf expansion, but the literature remains controversial about their respective contributions. Here, we tested the hypothesis that the importance of hydraulics and metabolics is organized according to both dark/light fluctuations and leaf ontogeny. For this purpose, we established the developmental pattern of individual leaf expansion during days and nights in the model plant Arabidopsis (Arabidopsis thaliana). Under control conditions, decreases in leaf expansion were observed at night immediately after emergence, when starch reserves were lowest. These nocturnal decreases were strongly exaggerated in a set of starch mutants, consistent with an early carbon limitation. However, low-light treatment of wild-type plants had no influence on these early decreases, implying that expansion can be uncoupled from changes in carbon availability. From 4 d after leaf emergence onward, decreases of leaf expansion were observed in the daytime. Using mutants impaired in stomatal control of transpiration as well as plants grown under soil water deficit or high air humidity, we gathered evidence that these diurnal decreases were the signature of a hydraulic limitation that gradually set up as the leaf developed. Changes in leaf turgor were consistent with this pattern. It is concluded that during the course of leaf ontogeny, the predominant control of leaf expansion switches from metabolics to hydraulics. We suggest that the leaf is better armed to buffer variations in the former than in the latter.

  2. Conserved and novel responses to cytokinin treatments during flower and fruit development in Brassica napus and Arabidopsis thaliana.

    PubMed

    Zuñiga-Mayo, Victor M; Baños-Bayardo, Cesar R; Díaz-Ramírez, David; Marsch-Martínez, Nayelli; de Folter, Stefan

    2018-05-01

    Hormones are an important component in the regulatory networks guiding plant development. Cytokinins are involved in different physiological and developmental processes in plants. In the model plant Arabidopsis thaliana, cytokinin application during gynoecium development produces conspicuous phenotypes. On the other hand, Brassica napus, also known as canola, is a crop plant belonging to the Brassicaceae family, as A. thaliana. This makes B. napus a good candidate to study whether the cytokinin responses observed in A. thaliana are conserved in the same plant family. Here, we observed that cytokinin treatment in B. napus affects different traits of flower and fruit development. It increases ovule and seed number, affects stamen filament elongation and anther maturation, and causes a conspicuous overgrowth of tissue in petals and gynoecia. Furthermore, cytokinin recovers replum development in both wild type B. napus and in the A. thaliana rpl ntt double mutant, in which no replum is visible. These results indicate both conserved and novel responses to cytokinin in B. napus. Moreover, in this species, some cytokinin-induced phenotypes are inherited to the next, untreated generation, suggesting that cytokinins may trigger epigenetic modifications.

  3. Analysis of the function of the photoreceptors phytochrome B and phytochrome D in Nicotiana plumbaginifolia and Arabidopsis thaliana.

    PubMed

    Fernández, Aurora Piñas; Gil, Patricia; Valkai, Ildiko; Nagy, Ferenc; Schäfer, Eberhard

    2005-05-01

    To investigate the mechanism of phytochrome action in vivo, NtPHYB, AtPHYB and phyD:green fluorescent protein (GFP) were overexpressed in Nicotiana plumbaginifolia and Arabidopsis thaliana. The expression of 35S:NtPHYB:GFP and 35S:AtPHYB:GFP complemented the tobacco hgl2 and Arabidopsis phyB-9 mutations, whereas the 35S:AtPHYD:GFP only rescued the hgl2 mutant. All three fusion proteins are transported into the nucleus in all genetic backgrounds. These data indicate that AtPHYD:GFP is biologically active and functions as the main red light receptor in transgenic tobacco, and establish an experimental system for the functional analysis of this elusive photoreceptor in vivo.

  4. Phenotypic Effects of Salt and Heat Stress over Three Generations in Arabidopsis thaliana

    PubMed Central

    Suter, Léonie; Widmer, Alex

    2013-01-01

    Current and predicted environmental change will force many organisms to adapt to novel conditions, especially sessile organisms such as plants. It is therefore important to better understand how plants react to environmental stress and to what extent genotypes differ in such responses. It has been proposed that adaptation to novel conditions could be facilitated by heritable epigenetic changes induced by environmental stress, independent of genetic variation. Here we assessed phenotypic effects of heat and salt stress within and across three generations using four highly inbred Arabidopsis thaliana genotypes (Col, Cvi, Ler and Sha). Salt stress generally decreased fitness, but genotypes were differently affected, suggesting that susceptibility of A. thaliana to salt stress varies among genotypes. Heat stress at an early rosette stage had less detrimental effects but accelerated flowering in three out of four accessions. Additionally, we found three different modes of transgenerational effects on phenotypes, all harboring the potential of being adaptive: heat stress in previous generations induced faster rosette growth in Sha, both under heat and control conditions, resembling a tracking response, while in Cvi, the phenotypic variance of several traits increased, resembling diversified bet-hedging. Salt stress experienced in earlier generations altered plant architecture of Sha under salt but not control conditions, similar to transgenerational phenotypic plasticity. However, transgenerational phenotypic effects depended on the type of stress as well as on genotype, suggesting that such effects may not be a general response leading to adaptation to novel environmental conditions in A. thaliana. PMID:24244719

  5. Induction of plant virus defense response by brassinosteroids and brassinosteroid signaling in Arabidopsis thaliana.

    PubMed

    Zhang, Da-Wei; Deng, Xing-Guang; Fu, Fa-Qiong; Lin, Hong-Hui

    2015-04-01

    Our study demonstrated that CMV resistance was upregulated by brassinosteroids (BRs) treatment, and BR signaling was needed for this BRs-induced CMV tolerance. Plant steroid hormones, brassinosteroids (BRs), play essential roles in variety of plant developmental processes and adaptation to various biotic and abiotic stresses. BR signal through plasma membrane-localized receptor and other components to modulate several transcription factors that modulate thousands of target genes including certain stress-responsive genes. To study the effects of BRs on plant virus defense and how BRs induce plant virus stress tolerance, we manipulated the BRs levels in Arabidopsis thaliana and found that BRs levels were positively correlated with the tolerance to Cucumber mosaic virus (CMV). We also showed that BRs treatment alleviated photosystem damage, enhanced antioxidant enzymes activity and induced defense-associated genes expression under CMV stress in Arabidopsis. To see whether BR signaling is essential for the plant virus defense response, we made use of BR signaling mutants (a weak allele of the BRs receptor mutant bri1-5 and constitutive BRs response mutant bes1-D). Compared with wild-type Arabidopsis plants, bri1-5 displayed reversed tolerance to CMV, but the resistance was enhanced in bes1-D. Together our results suggest that BRs can induce plant virus defense response through BR signaling.

  6. Genetic analysis of indole-3-butyric acid responses in Arabidopsis thaliana reveals four mutant classes.

    PubMed Central

    Zolman, B K; Yoder, A; Bartel, B

    2000-01-01

    Indole-3-butyric acid (IBA) is widely used in agriculture because it induces rooting. To better understand the in vivo role of this endogenous auxin, we have identified 14 Arabidopsis mutants that are resistant to the inhibitory effects of IBA on root elongation, but that remain sensitive to the more abundant auxin indole-3-acetic acid (IAA). These mutants have defects in various IBA-mediated responses, which allowed us to group them into four phenotypic classes. Developmental defects in the absence of exogenous sucrose suggest that some of these mutants are impaired in peroxisomal fatty acid chain shortening, implying that the conversion of IBA to IAA is also disrupted. Other mutants appear to have normal peroxisomal function; some of these may be defective in IBA transport, signaling, or response. Recombination mapping indicates that these mutants represent at least nine novel loci in Arabidopsis. The gene defective in one of the mutants was identified using a positional approach and encodes PEX5, which acts in the import of most peroxisomal matrix proteins. These results indicate that in Arabidopsis thaliana, IBA acts, at least in part, via its conversion to IAA. PMID:11063705

  7. Conserved and Novel Functions for Arabidopsis thaliana MIA40 in Assembly of Proteins in Mitochondria and Peroxisomes

    PubMed Central

    Carrie, Chris; Giraud, Estelle; Duncan, Owen; Xu, Lin; Wang, Yan; Huang, Shaobai; Clifton, Rachel; Murcha, Monika; Filipovska, Aleksandra; Rackham, Oliver; Vrielink, Alice; Whelan, James

    2010-01-01

    The disulfide relay system of the mitochondrial intermembrane space has been extensively characterized in Saccharomyces cerevisiae. It contains two essential components, Mia40 and Erv1. The genome of Arabidopsis thaliana contains a single gene for each of these components. Although insertional inactivation of Erv1 leads to a lethal phenotype, inactivation of Mia40 results in no detectable deleterious phenotype. A. thaliana Mia40 is targeted to and accumulates in mitochondria and peroxisomes. Inactivation of Mia40 results in an alteration of several proteins in mitochondria, an absence of copper/zinc superoxide dismutase (CSD1), the chaperone for superoxide dismutase (Ccs1) that inserts copper into CSD1, and a decrease in capacity and amount of complex I. In peroxisomes the absence of Mia40 leads to an absence of CSD3 and a decrease in abnormal inflorescence meristem 1 (Aim1), a β-oxidation pathway enzyme. Inactivation of Mia40 leads to an alteration of the transcriptome of A. thaliana, with genes encoding peroxisomal proteins, redox functions, and biotic stress significantly changing in abundance. Thus, the mechanistic operation of the mitochondrial disulfide relay system is different in A. thaliana compared with other systems, and Mia40 has taken on new roles in peroxisomes and mitochondria. PMID:20829360

  8. Arabidopsis thaliana EPOXIDE HYDROLASE1 (AtEH1) is a cytosolic epoxide hydrolase involved in the synthesis of poly-hydroxylated cutin monomers.

    PubMed

    Pineau, Emmanuelle; Xu, Lin; Renault, Hugues; Trolet, Adrien; Navrot, Nicolas; Ullmann, Pascaline; Légeret, Bertrand; Verdier, Gaëtan; Beisson, Fred; Pinot, Franck

    2017-07-01

    Epoxide hydrolases (EHs) are present in all living organisms. They have been extensively characterized in mammals; however, their biological functions in plants have not been demonstrated. Based on in silico analysis, we identified AtEH1 (At3g05600), a putative Arabidopsis thaliana epoxide hydrolase possibly involved in cutin monomer synthesis. We expressed AtEH1 in yeast and studied its localization in vivo. We also analyzed the composition of cutin from A. thaliana lines in which this gene was knocked out. Incubation of recombinant AtEH1 with epoxy fatty acids confirmed its capacity to hydrolyze epoxides of C18 fatty acids into vicinal diols. Transfection of Nicotiana benthamiana leaves with constructs expressing AtEH1 fused to enhanced green fluorescent protein (EGFP) indicated that AtEH1 is localized in the cytosol. Analysis of cutin monomers in loss-of-function Ateh1-1 and Ateh1-2 mutants showed an accumulation of 18-hydroxy-9,10-epoxyoctadecenoic acid and a concomitant decrease in corresponding vicinal diols in leaf and seed cutin. Compared with wild-type seeds, Ateh1 seeds showed delayed germination under osmotic stress conditions and increased seed coat permeability to tetrazolium red. This work reports a physiological role for a plant EH and identifies AtEH1 as a new member of the complex machinery involved in cutin synthesis. © 2017 CNRS New Phytologist © 2017 New Phytologist Trust.

  9. Mutation of the Inducible ARABIDOPSIS THALIANA CYTOCHROME P450 REDUCTASE2 Alters Lignin Composition and Improves Saccharification1[W][OPEN

    PubMed Central

    Sundin, Lisa; Vanholme, Ruben; Geerinck, Jan; Goeminne, Geert; Höfer, René; Kim, Hoon; Ralph, John; Boerjan, Wout

    2014-01-01

    ARABIDOPSIS THALIANA CYTOCHROME P450 REDUCTASE1 (ATR1) and ATR2 provide electrons from NADPH to a large number of CYTOCHROME P450 (CYP450) enzymes in Arabidopsis (Arabidopsis thaliana). Whereas ATR1 is constitutively expressed, the expression of ATR2 appears to be induced during lignin biosynthesis and upon stresses. Therefore, ATR2 was hypothesized to be preferentially involved in providing electrons to the three CYP450s involved in lignin biosynthesis: CINNAMATE 4-HYDROXYLASE (C4H), p-COUMARATE 3-HYDROXYLASE1 (C3H1), and FERULATE 5-HYDROXYLASE1 (F5H1). Here, we show that the atr2 mutation resulted in a 6% reduction in total lignin amount in the main inflorescence stem and a compositional shift of the remaining lignin to a 10-fold higher fraction of p-hydroxyphenyl units at the expense of syringyl units. Phenolic profiling revealed shifts in lignin-related phenolic metabolites, in particular with the substrates of C4H, C3H1 and F5H1 accumulating in atr2 mutants. Glucosinolate and flavonol glycoside biosynthesis, both of which also rely on CYP450 activities, appeared less affected. The cellulose in the atr2 inflorescence stems was more susceptible to enzymatic hydrolysis after alkaline pretreatment, making ATR2 a potential target for engineering plant cell walls for biofuel production. PMID:25315601

  10. Identification, occurrence, and validation of DRE and ABRE Cis-regulatory motifs in the promoter regions of genes of Arabidopsis thaliana.

    PubMed

    Mishra, Sonal; Shukla, Aparna; Upadhyay, Swati; Sanchita; Sharma, Pooja; Singh, Seema; Phukan, Ujjal J; Meena, Abha; Khan, Feroz; Tripathi, Vineeta; Shukla, Rakesh Kumar; Shrama, Ashok

    2014-04-01

    Plants posses a complex co-regulatory network which helps them to elicit a response under diverse adverse conditions. We used an in silico approach to identify the genes with both DRE and ABRE motifs in their promoter regions in Arabidopsis thaliana. Our results showed that Arabidopsis contains a set of 2,052 genes with ABRE and DRE motifs in their promoter regions. Approximately 72% or more of the total predicted 2,052 genes had a gap distance of less than 400 bp between DRE and ABRE motifs. For positional orientation of the DRE and ABRE motifs, we found that the DR form (one in direct and the other one in reverse orientation) was more prevalent than other forms. These predicted 2,052 genes include 155 transcription factors. Using microarray data from The Arabidopsis Information Resource (TAIR) database, we present 44 transcription factors out of 155 which are upregulated by more than twofold in response to osmotic stress and ABA treatment. Fifty-one transcripts from the one predicted above were validated using semiquantitative expression analysis to support the microarray data in TAIR. Taken together, we report a set of genes containing both DRE and ABRE motifs in their promoter regions in A. thaliana, which can be useful to understand the role of ABA under osmotic stress condition. © 2013 Institute of Botany, Chinese Academy of Sciences.

  11. A Brassica rapa Linkage Map of EST-based SNP Markers for Identification of Candidate Genes Controlling Flowering Time and Leaf Morphological Traits

    PubMed Central

    Li, Feng; Kitashiba, Hiroyasu; Inaba, Kiyofumi; Nishio, Takeshi

    2009-01-01

    For identification of genes responsible for varietal differences in flowering time and leaf morphological traits, we constructed a linkage map of Brassica rapa DNA markers including 170 EST-based markers, 12 SSR markers, and 59 BAC sequence-based markers, of which 151 are single nucleotide polymorphism (SNP) markers. By BLASTN, 223 markers were shown to have homologous regions in Arabidopsis thaliana, and these homologous loci covered nearly the whole genome of A. thaliana. Synteny analysis between B. rapa and A. thaliana revealed 33 large syntenic regions. Three quantitative trait loci (QTLs) for flowering time were detected. BrFLC1 and BrFLC2 were linked to the QTLs for bolting time, budding time, and flowering time. Three SNPs in the promoter, which may be the cause of low expression of BrFLC2 in the early-flowering parental line, were identified. For leaf lobe depth and leaf hairiness, one major QTL corresponding to a syntenic region containing GIBBERELLIN 20 OXIDASE 3 and one major QTL containing BrGL1, respectively, were detected. Analysis of nucleotide sequences and expression of these genes suggested possible involvement of these genes in leaf morphological traits. PMID:19884167

  12. Alternate approaches to repress endogenous microRNA activity in Arabidopsis thaliana

    PubMed Central

    Wang, Ming-Bo

    2011-01-01

    MicroRnAs (miRnAs) are an endogenous class of regulatory small RnA (sRnA). in plants, miRnAs are processed from short non-protein-coding messenger RnAs (mRnAs) transcribed from small miRnA genes (MIR genes). Traditionally in the model plant Arabidopsis thaliana (Arabidopsis), the functional analysis of a gene product has relied on the identification of a corresponding T-DnA insertion knockout mutant from a large, randomly-mutagenized population. However, because of the small size of MIR genes and presence of multiple, highly conserved members in most plant miRnA families, it has been extremely laborious and time consuming to obtain a corresponding single or multiple, null mutant plant line. Our recent study published in Molecular Plant1 outlines an alternate method for the functional characterization of miRnA action in Arabidopsis, termed anti-miRnA technology. Using this approach we demonstrated that the expression of individual miRnAs or entire miRnA families, can be readily and efficiently knocked-down. Our approach is in addition to two previously reported methodologies that also allow for the targeted suppression of either individual miRnAs, or all members of a MIR gene family; these include miRnA target mimicry2,3 and transcriptional gene silencing (TGS) of MIR gene promoters.4 All three methodologies rely on endogenous gene regulatory machinery and in this article we provide an overview of these technologies and discuss their strengths and weaknesses in inhibiting the activity of their targeted miRnA(s). PMID:21358288

  13. Roles of miR319 and TCP Transcription Factors in Leaf Development1[OPEN

    PubMed Central

    2017-01-01

    Sophisticated regulation of gene expression, including microRNAs (miRNAs) and their target genes, is required for leaf differentiation, growth, and senescence. The impact of miR319 and its target TEOSINTE BRANCHED1, CYCLOIDEA, and PROLIFERATING CELL NUCLEAR ANTIGEN BINDING FACTOR (TCP) genes on leaf development has been extensively investigated, but the redundancies of these gene families often interfere with the evaluation of their function and regulation in the developmental context. Here, we present the genetic evidence of the involvement of the MIR319 and TCP gene families in Arabidopsis (Arabidopsis thaliana) leaf development. Single mutations in MIR319A and MIR319B genes moderately inhibited the formation of leaf serrations, whereas double mutations increased the extent of this inhibition and resulted in the formation of smooth leaves. Mutations in MIR319 and gain-of-function mutations in the TCP4 gene conferred resistance against miR319 and impaired the cotyledon boundary and leaf serration formation. These mutations functionally associated with CUP-SHAPED COTYLEDON genes, which regulate the cotyledon boundary and leaf serration formation. In contrast, loss-of-function mutations in miR319-targeted and nontargeted TCP genes cooperatively induced the formation of serrated leaves in addition to changes in the levels of their downstream gene transcript. Taken together, these findings demonstrate that the MIR319 and TCP gene families underlie robust and multilayer control of leaf development. This study also provides a framework toward future researches on redundant miRNAs and transcription factors in Arabidopsis and crop plants. PMID:28842549

  14. Fusicoccin-Binding Proteins in Arabidopsis thaliana (L.) Heynh. 1

    PubMed Central

    Meyer, Christiane; Feyerabend, Martin; Weiler, Elmar W.

    1989-01-01

    Using the novel radioligand, [3H]-9′-nor-fusicoccin-8′-alcohol, high affinity binding sites for fusicoccin were characterized in preparations from leaves of Arabidopsis thaliana (L.) Heynh. The binding site copartitioned with the plasmalemma marker, vanadate-sensitive K+, Mg2+-ATPase, when microsomal fractions were further purified by aqueous two-phase partitioning in polyethylene glycol-dextran phase systems and sedimented at an equilibrium density of 1.17 grams per cubic centimeter in continuous sucrose density gradients, as did the ATPase marker. The binding of [3H]-9′-nor-fusicoccin-8′-alcohol was saturable and Scatchard analysis revealed a biphasic plot with two apparent dissociation constants (KD), KD1 = 1.5 nanomolar and KD2 = 42 nanomolar, for the radioligand. Binding was optimal at pH 6, thermolabile, and was reduced by 70% when the membrane vesicles were pretreated with trypsin. The data are consistent with the presence of one or several binding proteins for fusicoccin at the plasma membrane of A. thaliana. Binding of the radioligand was unaffected by pretreatment of the sites with various alkylating and reducing agents, but was reduced by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, diethylpyrocarbonate, chloramine T, and periodate. A number of detergents were tested to find optimum conditions for solubilization. Nonanoyl-N-methylglucamide (50 millimolar) solubilized 70% of the radioligand-binding protein complex in undissociated form. Photoaffinity labeling of membrane preparations with a tritiated azido analog of fusicoccin resulted in the labeling of a 34 ± 1 kilodalton polypeptide. Labeling of this polypeptide, presumably the fusicoccin-binding protein, was severely reduced in the presence of unlabeled fusicoccin. PMID:16666603

  15. The application of Arabidopsis thaliana in studying tripartite interactions among plants, beneficial fungal endophytes and biotrophic plant-parasitic nematodes.

    PubMed

    Martinuz, Alfonso; Zewdu, Getaneh; Ludwig, Nicole; Grundler, Florian; Sikora, Richard A; Schouten, Alexander

    2015-04-01

    The research demonstrated that Arabidopsis can be used as a model system for studying plant-nematode-endophyte tripartite interactions; thus, opening new possibilities for further characterizing the molecular mechanisms behind these interactions. Arabidopsis has been established as an important model system for studying plant biology and plant-microbe interactions. We show that this plant can also be used for studying the tripartite interactions among plants, the root-knot nematode Meloidogyne incognita and a beneficial endophytic isolate of Fusarium oxysporum, strain Fo162. In various plant species, Fo162 can systemically reduce M. incognita infection development and fecundity. Here it is shown that Fo162 can also colonize A. thaliana roots without causing disease symptoms, thus behaving as a typical endophyte. As observed for other plants, this endophyte could not migrate from the roots into the shoots and leaves. Direct inoculation of the leaves also did not result in colonization of the plant. A significant increase in plant fresh weight, root length and average root diameter was observed, suggesting the promotion of plant growth by the endophyte. The inoculation of A. thaliana with F. oxysporum strain Fo162 also resulted in a significant reduction in the number of M. incognita juveniles infecting the roots and ultimately the number of galls produced. This was also observed in a split-root experiment, in which the endophyte and nematode were spatially separated. The usefulness of Arabidopsis opens new possibilities for further dissecting complex tripartite interactions at the molecular and biochemical level.

  16. An epifluorescent attachment improves whole-plant digital photography of Arabidopsis thaliana expressing red-shifted green fluorescent protein

    PubMed Central

    Baker, Stokes S.; Vidican, Cleo B.; Cameron, David S.; Greib, Haittam G.; Jarocki, Christine C.; Setaputri, Andres W.; Spicuzza, Christopher H.; Burr, Aaron A.; Waqas, Meriam A.; Tolbert, Danzell A.

    2012-01-01

    Background and aims Studies have shown that levels of green fluorescent protein (GFP) leaf surface fluorescence are directly proportional to GFP soluble protein concentration in transgenic plants. However, instruments that measure GFP surface fluorescence are expensive. The goal of this investigation was to develop techniques with consumer digital cameras to analyse GFP surface fluorescence in transgenic plants. Methodology Inexpensive filter cubes containing machine vision dichroic filters and illuminated with blue light-emitting diodes (LED) were designed to attach to digital single-lens reflex (SLR) camera macro lenses. The apparatus was tested on purified enhanced GFP, and on wild-type and GFP-expressing arabidopsis grown autotrophically and heterotrophically. Principal findings Spectrum analysis showed that the apparatus illuminates specimens with wavelengths between ∼450 and ∼500 nm, and detects fluorescence between ∼510 and ∼595 nm. Epifluorescent photographs taken with SLR digital cameras were able to detect red-shifted GFP fluorescence in Arabidopsis thaliana leaves and cotyledons of pot-grown plants, as well as roots, hypocotyls and cotyledons of etiolated and light-grown plants grown heterotrophically. Green fluorescent protein fluorescence was detected primarily in the green channel of the raw image files. Studies with purified GFP produced linear responses to both protein surface density and exposure time (H0: β (slope) = 0 mean counts per pixel (ng s mm−2)−1, r2 > 0.994, n = 31, P < 1.75 × 10−29). Conclusions Epifluorescent digital photographs taken with complementary metal-oxide-semiconductor and charge-coupled device SLR cameras can be used to analyse red-shifted GFP surface fluorescence using visible blue light. This detection device can be constructed with inexpensive commercially available materials, thus increasing the accessibility of whole-organism GFP expression analysis to research laboratories and teaching institutions with

  17. Temperature fine-tunes Mediterranean Arabidopsis thaliana life-cycle phenology geographically.

    PubMed

    Marcer, A; Vidigal, D S; James, P M A; Fortin, M-J; Méndez-Vigo, B; Hilhorst, H W M; Bentsink, L; Alonso-Blanco, C; Picó, F X

    2018-01-01

    To understand how adaptive evolution in life-cycle phenology operates in plants, we need to unravel the effects of geographic variation in putative agents of natural selection on life-cycle phenology by considering all key developmental transitions and their co-variation patterns. We address this goal by quantifying the temperature-driven and geographically varying relationship between seed dormancy and flowering time in the annual Arabidopsis thaliana across the Iberian Peninsula. We used data on genetic variation in two major life-cycle traits, seed dormancy (DSDS50) and flowering time (FT), in a collection of 300 A. thaliana accessions from the Iberian Peninsula. The geographically varying relationship between life-cycle traits and minimum temperature, a major driver of variation in DSDS50 and FT, was explored with geographically weighted regressions (GWR). The environmentally varying correlation between DSDS50 and FT was analysed by means of sliding window analysis across a minimum temperature gradient. Maximum local adjustments between minimum temperature and life-cycle traits were obtained in the southwest Iberian Peninsula, an area with the highest minimum temperatures. In contrast, in off-southwest locations, the effects of minimum temperature on DSDS50 were rather constant across the region, whereas those of minimum temperature on FT were more variable, with peaks of strong local adjustments of GWR models in central and northwest Spain. Sliding window analysis identified a minimum temperature turning point in the relationship between DSDS50 and FT around a minimum temperature of 7.2 °C. Above this minimum temperature turning point, the variation in the FT/DSDS50 ratio became rapidly constrained and the negative correlation between FT and DSDS50 did not increase any further with increasing minimum temperatures. The southwest Iberian Peninsula emerges as an area where variation in life-cycle phenology appears to be restricted by the duration and severity

  18. Growing Arabidopsis in vitro: cell suspensions, in vitro culture, and regeneration.

    PubMed

    Barkla, Bronwyn J; Vera-Estrella, Rosario; Pantoja, Omar

    2014-01-01

    An understanding of basic methods in Arabidopsis tissue culture is beneficial for any laboratory working on this model plant. Tissue culture refers to the aseptic growth of cells, organs, or plants in a controlled environment, in which physical, nutrient, and hormonal conditions can all be easily manipulated and monitored. The methodology facilitates the production of a large number of plants that are genetically identical over a relatively short growth period. Techniques, including callus production, cell suspension cultures, and plant regeneration, are all indispensable tools for the study of cellular biochemical and molecular processes. Plant regeneration is a key technology for successful stable plant transformation, while cell suspension cultures can be exploited for metabolite profiling and mining. In this chapter we report methods for the successful and highly efficient in vitro regeneration of plants and production of stable cell suspension lines from leaf explants of both Arabidopsis thaliana and Arabidopsis halleri.

  19. Arabidopsis thaliana dehydroascorbate reductase 2: Conformational flexibility during catalysis

    NASA Astrophysics Data System (ADS)

    Bodra, Nandita; Young, David; Astolfi Rosado, Leonardo; Pallo, Anna; Wahni, Khadija; de Proft, Frank; Huang, Jingjing; van Breusegem, Frank; Messens, Joris

    2017-02-01

    Dehydroascorbate reductase (DHAR) catalyzes the glutathione (GSH)-dependent reduction of dehydroascorbate and plays a direct role in regenerating ascorbic acid, an essential plant antioxidant vital for defense against oxidative stress. DHAR enzymes bear close structural homology to the glutathione transferase (GST) superfamily of enzymes and contain the same active site motif, but most GSTs do not exhibit DHAR activity. The presence of a cysteine at the active site is essential for the catalytic functioning of DHAR, as mutation of this cysteine abolishes the activity. Here we present the crystal structure of DHAR2 from Arabidopsis thaliana with GSH bound to the catalytic cysteine. This structure reveals localized conformational differences around the active site which distinguishes the GSH-bound DHAR2 structure from that of DHAR1. We also unraveled the enzymatic step in which DHAR releases oxidized glutathione (GSSG). To consolidate our structural and kinetic findings, we investigated potential conformational flexibility in DHAR2 by normal mode analysis and found that subdomain mobility could be linked to GSH binding or GSSG release.

  20. 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

  1. A cadmium-sensitive, glutathione-deficient mutant of Arabidopsis thaliana.

    PubMed Central

    Howden, R; Andersen, C R; Goldsbrough, P B; Cobbett, C S

    1995-01-01

    The roots of the cadmium-sensitive mutant of Arabidopsis thaliana, cad1-1, become brown in the presence of cadmium. A new cadmium-sensitive mutant affected at a second locus, cad2, has been identified using this phenotype. Genetic analysis has grown that the sensitive phenotype is recessive to the wild type and segregates as a single Mendelian locus. Assays of cadmium accumulation by intact plants indicated that the mutant is deficient in its ability to sequester cadmium. Undifferentiated callus tissue was also cadmium sensitive, suggesting that the mutant phenotype is expressed at the cellular level. The level of cadmium-binding complexes formed in vivo was decreased compared with the wild type and accumulation of phytochelatins was about 10% of that in the wild type. The level of glutathione, the substrate for phytochelatin biosynthesis, in tissues of the mutant was decreased to about 15 to 30% of that in the wild type. Thus, the deficiency in phytochelatin biosynthesis can be explained by a deficiency in glutathione. PMID:7770518

  2. Arabidopsis thaliana dehydroascorbate reductase 2: Conformational flexibility during catalysis

    PubMed Central

    Bodra, Nandita; Young, David; Astolfi Rosado, Leonardo; Pallo, Anna; Wahni, Khadija; De Proft, Frank; Huang, Jingjing; Van Breusegem, Frank; Messens, Joris

    2017-01-01

    Dehydroascorbate reductase (DHAR) catalyzes the glutathione (GSH)-dependent reduction of dehydroascorbate and plays a direct role in regenerating ascorbic acid, an essential plant antioxidant vital for defense against oxidative stress. DHAR enzymes bear close structural homology to the glutathione transferase (GST) superfamily of enzymes and contain the same active site motif, but most GSTs do not exhibit DHAR activity. The presence of a cysteine at the active site is essential for the catalytic functioning of DHAR, as mutation of this cysteine abolishes the activity. Here we present the crystal structure of DHAR2 from Arabidopsis thaliana with GSH bound to the catalytic cysteine. This structure reveals localized conformational differences around the active site which distinguishes the GSH-bound DHAR2 structure from that of DHAR1. We also unraveled the enzymatic step in which DHAR releases oxidized glutathione (GSSG). To consolidate our structural and kinetic findings, we investigated potential conformational flexibility in DHAR2 by normal mode analysis and found that subdomain mobility could be linked to GSH binding or GSSG release. PMID:28195196

  3. Use of the "gl1" Mutant and the "CA-rop2" Transgenic Plants of "Arabidopsis thaliana" in the Biology Laboratory Course

    ERIC Educational Resources Information Center

    Zheng, Zhi-Liang

    2006-01-01

    This article describes the use of the "glabrous1 (g11)" mutant and constitutively active "(CA)-rop2" transgenic plants of "Arabidopsis thaliana" in teaching genetics laboratory for both high school and undergraduate students. The experiments provide students with F[subscript 1] and F[subscript 2] generations within a semester for genetic and…

  4. CKB1 is involved in abscisic acid and gibberellic acid signaling to regulate stress responses in Arabidopsis thaliana.

    PubMed

    Yuan, Congying; Ai, Jianping; Chang, Hongping; Xiao, Wenjun; Liu, Lu; Zhang, Cheng; He, Zhuang; Huang, Ji; Li, Jinyan; Guo, Xinhong

    2017-05-01

    Casein kinase II (CK2), an evolutionarily well-conserved Ser/Thr kinase, plays critical roles in all higher organisms including plants. CKB1 is a regulatory subunit beta of CK2. In this study, homozygous T-DNA mutants (ckb1-1 and ckb1-2) and over-expression plants (35S:CKB1-1, 35S:CKB1-2) of Arabidopsis thaliana were studied to understand the role of CKB1 in abiotic stress and gibberellic acid (GA) signaling. Histochemical staining showed that although CKB1 was expressed in all organs, it had a relatively higher expression in conducting tissues. The ckb1 mutants showed reduced sensitivity to abscisic acid (ABA) during seed germination and seedling growth. The increased stomatal aperture, leaf water loss and proline accumulation were observed in ckb1 mutants. In contrast, the ckb1 mutant had increased sensitivity to polyaluminum chloride during seed germination and hypocotyl elongation. We obtained opposite results in over-expression plants. The expression levels of a number of genes in the ABA and GA regulatory network had changed. This study demonstrates that CKB1 is an ABA signaling-related gene, which subsequently influences GA metabolism, and may play a positive role in ABA signaling.

  5. The combined effect of uranium and gamma radiation on biological responses and oxidative stress induced in Arabidopsis thaliana.

    PubMed

    Vanhoudt, Nathalie; Vandenhove, Hildegarde; Horemans, Nele; Wannijn, Jean; Van Hees, May; Vangronsveld, Jaco; Cuypers, Ann

    2010-11-01

    Uranium never occurs as a single pollutant in the environment, but always in combination with other stressors such as ionizing radiation. As effects induced by multiple contaminants can differ markedly from the effects induced by the individual stressors, this multiple pollution context should not be neglected. In this study, effects on growth, nutrient uptake and oxidative stress induced by the single stressors uranium and gamma radiation are compared with the effects induced by the combination of both stressors. By doing this, we aim to better understand the effects induced by the combined stressors but also to get more insight in stressor-specific response mechanisms. Eighteen-day-old Arabidopsis thaliana seedlings were exposed for 3 days to 10 muM uranium and 3.5 Gy gamma radiation. Gamma radiation interfered with uranium uptake, resulting in decreased uranium concentrations in the roots, but with higher transport to the leaves. This resulted in a better root growth but increased leaf lipid peroxidation. For the other endpoints studied, effects under combined exposure were mostly determined by uranium presence and only limited influenced by gamma presence. Furthermore, an important role is suggested for CAT1/2/3 gene expression under uranium and mixed stressor conditions in the leaves.

  6. Soil mixture composition alters Arabidopsis susceptibility to Pseudomonas syringae infection

    USDA-ARS?s Scientific Manuscript database

    Pseudomonas syringae is a Gram-negative bacterial pathogen that causes disease on more than 100 different plant species, including the model plant Arabidopsis thaliana. Dissection of the Arabidopsis thaliana-Pseudomonas syringae pathosystem has identified many factors that contribute to successful ...

  7. 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. © 2015 John Wiley & Sons Ltd.

  8. Phytotoxic effects of trichothecenes on the growth and morphology of Arabidopsis thaliana.

    PubMed

    Masuda, Daisuke; Ishida, Mamoru; Yamaguchi, Kazuo; Yamaguchi, Isamu; Kimura, Makoto; Nishiuchi, Takumi

    2007-01-01

    Non-volatile sesquiterpenoids, a trichothecene family of phytotoxins such as deoxynivalenol (DON) and T-2 toxin, contain numerous molecular species and are synthesized by phytopathogenic Fusarium species. Although trichothecene chemotypes might play a role in the virulence of individual Fusarium strains, the phytotoxic action of individual trichothecenes has not been systematically studied. To perform a comparative analysis of the phytotoxic action of representative trichothecenes, the growth and morphology of Arabidopsis thaliana growing on media containing these compounds was investigated. Both DON and diacetoxyscirpenol (DAS) preferentially inhibited root elongation. DON-treated roots were less organized compared with control roots. Moreover, preferential inhibition of root growth by DON was also observed in wheat plants. In addition, T-2 toxin-treated seedlings exhibited dwarfism with aberrant morphological changes (e.g. petiole shortening, curled dark-green leaves, and reduced cell size). These results imply that the phytotoxic action of trichothecenes differed among their molecular species. Cycloheximide (CHX)-treated seedlings displayed neither feature, although it is known that trichothecenes inhibit translation in eukaryotic ribosomes. Microarray analyses suggested that T-2 toxin caused a defence response, the inactivation of brassinosteroid (BR), and the generation of reactive oxygen species in Arabidopsis. This observation is in agreement with our previous reports in which trichothecenes such as T-2 toxin have an elicitor-like activity when infiltrated into the leaves of Arabidopsis. Since it has been reported that BR plays an important role in a broad range of disease resistance in tobacco and rice, inactivation of BR might affect pathogenicity during the infection of host plants by trichothecene-producing fungi.

  9. Phytoremediation of arsenic from the contaminated soil using transgenic tobacco plants expressing ACR2 gene of Arabidopsis thaliana.

    PubMed

    Nahar, Noor; Rahman, Aminur; Nawani, Neelu N; Ghosh, Sibdas; Mandal, Abul

    2017-11-01

    We have cloned, characterized and transformed the AtACR2 gene (arsenic reductase 2) of Arabidopsis thaliana into the genome of tobacco (Nicotiana tabacum, var Sumsun). Our results revealed that the transgenic tobacco plants are more tolerant to arsenic than the wild type ones. These plants can grow on culture medium containing 200μM arsenate, whereas the wild type can barely survive under this condition. Furthermore, when exposed to 100μM arsenate for 35days the amount of arsenic accumulated in the shoots of transgenic plants was significantly lower (28μg/g d wt.) than that found in the shoots of non-transgenic controls (40μg/g d wt.). However, the arsenic content in the roots of transgenic plants was significantly higher (2400μg/g d. wt.) than that (2100μg/g d. wt.) observed in roots of wild type plants. We have demonstrated that Arabidopsis thaliana AtACR2 gene is a potential candidate for genetic engineering of plants to develop new crop cultivars that can be grown on arsenic contaminated fields to reduce arsenic content of the soil and can become a source of food containing no arsenic or exhibiting substantially reduced amount of this metalloid. Copyright © 2017 Elsevier GmbH. All rights reserved.

  10. Modeling the Metabolism of Arabidopsis thaliana: Application of Network Decomposition and Network Reduction in the Context of Petri Nets.

    PubMed

    Koch, Ina; Nöthen, Joachim; Schleiff, Enrico

    2017-01-01

    Motivation: Arabidopsis thaliana is a well-established model system for the analysis of the basic physiological and metabolic pathways of plants. Nevertheless, the system is not yet fully understood, although many mechanisms are described, and information for many processes exists. However, the combination and interpretation of the large amount of biological data remain a big challenge, not only because data sets for metabolic paths are still incomplete. Moreover, they are often inconsistent, because they are coming from different experiments of various scales, regarding, for example, accuracy and/or significance. Here, theoretical modeling is powerful to formulate hypotheses for pathways and the dynamics of the metabolism, even if the biological data are incomplete. To develop reliable mathematical models they have to be proven for consistency. This is still a challenging task because many verification techniques fail already for middle-sized models. Consequently, new methods, like decomposition methods or reduction approaches, are developed to circumvent this problem. Methods: We present a new semi-quantitative mathematical model of the metabolism of Arabidopsis thaliana . We used the Petri net formalism to express the complex reaction system in a mathematically unique manner. To verify the model for correctness and consistency we applied concepts of network decomposition and network reduction such as transition invariants, common transition pairs, and invariant transition pairs. Results: We formulated the core metabolism of Arabidopsis thaliana based on recent knowledge from literature, including the Calvin cycle, glycolysis and citric acid cycle, glyoxylate cycle, urea cycle, sucrose synthesis, and the starch metabolism. By applying network decomposition and reduction techniques at steady-state conditions, we suggest a straightforward mathematical modeling process. We demonstrate that potential steady-state pathways exist, which provide the fixed carbon to

  11. Leaf-GP: an open and automated software application for measuring growth phenotypes for arabidopsis and wheat.

    PubMed

    Zhou, Ji; Applegate, Christopher; Alonso, Albor Dobon; Reynolds, Daniel; Orford, Simon; Mackiewicz, Michal; Griffiths, Simon; Penfield, Steven; Pullen, Nick

    2017-01-01

    Plants demonstrate dynamic growth phenotypes that are determined by genetic and environmental factors. Phenotypic analysis of growth features over time is a key approach to understand how plants interact with environmental change as well as respond to different treatments. Although the importance of measuring dynamic growth traits is widely recognised, available open software tools are limited in terms of batch image processing, multiple traits analyses, software usability and cross-referencing results between experiments, making automated phenotypic analysis problematic. Here, we present Leaf-GP (Growth Phenotypes), an easy-to-use and open software application that can be executed on different computing platforms. To facilitate diverse scientific communities, we provide three software versions, including a graphic user interface (GUI) for personal computer (PC) users, a command-line interface for high-performance computer (HPC) users, and a well-commented interactive Jupyter Notebook (also known as the iPython Notebook) for computational biologists and computer scientists. The software is capable of extracting multiple growth traits automatically from large image datasets. We have utilised it in Arabidopsis thaliana and wheat ( Triticum aestivum ) growth studies at the Norwich Research Park (NRP, UK). By quantifying a number of growth phenotypes over time, we have identified diverse plant growth patterns between different genotypes under several experimental conditions. As Leaf-GP has been evaluated with noisy image series acquired by different imaging devices (e.g. smartphones and digital cameras) and still produced reliable biological outputs, we therefore believe that our automated analysis workflow and customised computer vision based feature extraction software implementation can facilitate a broader plant research community for their growth and development studies. Furthermore, because we implemented Leaf-GP based on open Python-based computer vision, image

  12. Chloroplast Dysfunction Causes Multiple Defects in Cell Cycle Progression in the Arabidopsis crumpled leaf Mutant1[C][W

    PubMed Central

    Hudik, Elodie; Yoshioka, Yasushi; Domenichini, Séverine; Bourge, Mickaël; Soubigout-Taconnat, Ludivine; Mazubert, Christelle; Yi, Dalong; Bujaldon, Sandrine; Hayashi, Hiroyuki; De Veylder, Lieven; Bergounioux, Catherine; Benhamed, Moussa; Raynaud, Cécile

    2014-01-01

    The majority of research on cell cycle regulation is focused on the nuclear events that govern the replication and segregation of the genome between the two daughter cells. However, eukaryotic cells contain several compartmentalized organelles with specialized functions, and coordination among these organelles is required for proper cell cycle progression, as evidenced by the isolation of several mutants in which both organelle function and overall plant development were affected. To investigate how chloroplast dysfunction affects the cell cycle, we analyzed the crumpled leaf (crl) mutant of Arabidopsis (Arabidopsis thaliana), which is deficient for a chloroplastic protein and displays particularly severe developmental defects. In the crl mutant, we reveal that cell cycle regulation is altered drastically and that meristematic cells prematurely enter differentiation, leading to reduced plant stature and early endoreduplication in the leaves. This response is due to the repression of several key cell cycle regulators as well as constitutive activation of stress-response genes, among them the cell cycle inhibitor SIAMESE-RELATED5. One unique feature of the crl mutant is that it produces aplastidic cells in several organs, including the root tip. By investigating the consequence of the absence of plastids on cell cycle progression, we showed that nuclear DNA replication occurs in aplastidic cells in the root tip, which opens future research prospects regarding the dialogue between plastids and the nucleus during cell cycle regulation in higher plants. PMID:25037213

  13. Long-Term Inhibition by Auxin of Leaf Blade Expansion in Bean and Arabidopsis1

    PubMed Central

    Keller, Christopher P.; Stahlberg, Rainer; Barkawi, Lana S.; Cohen, Jerry D.

    2004-01-01

    The role of auxin in controlling leaf expansion remains unclear. Experimental increases to normal auxin levels in expanding leaves have shown conflicting results, with both increases and decreases in leaf growth having been measured. Therefore, the effects of both auxin application and adjustment of endogenous leaf auxin levels on midrib elongation and final leaf size (fresh weight and area) were examined in attached primary monofoliate leaves of the common bean (Phaseolus vulgaris) and in early Arabidopsis rosette leaves. Aqueous auxin application inhibited long-term leaf blade elongation. Bean leaves, initially 40 to 50 mm in length, treated once with α-naphthalene acetic acid (1.0 mm), were, after 6 d, approximately 80% the length and weight of controls. When applied at 1.0 and 0.1 mm, α-naphthalene acetic acid significantly inhibited long-term leaf growth. The weak auxin, β-naphthalene acetic acid, was effective at 1.0 mm; and a weak acid control, benzoic acid, was ineffective. Indole-3-acetic acid (1 μm, 10 μm, 0.1 mm, and 1 mm) required daily application to be effective at any concentration. Application of the auxin transport inhibitor, 1-N-naphthylphthalamic acid (1% [w/w] in lanolin), to petioles also inhibited long-term leaf growth. This treatment also was found to lead to a sustained elevation of leaf free indole-3-acetic acid content relative to untreated control leaves. Auxin-induced inhibition of leaf growth appeared not to be mediated by auxin-induced ethylene synthesis because growth inhibition was not rescued by inhibition of ethylene synthesis. Also, petiole treatment of Arabidopsis with 1-N-naphthylphthalamic acid similarly inhibited leaf growth of both wild-type plants and ethylene-insensitive ein4 mutants. PMID:14988474

  14. Population genomics of the Arabidopsis thaliana flowering time gene network.

    PubMed

    Flowers, Jonathan M; Hanzawa, Yoshie; Hall, Megan C; Moore, Richard C; Purugganan, Michael D

    2009-11-01

    The time to flowering is a key component of the life-history strategy of the model plant Arabidopsis thaliana that varies quantitatively among genotypes. A significant problem for evolutionary and ecological genetics is to understand how natural selection may operate on this ecologically significant trait. Here, we conduct a population genomic study of resequencing data from 52 genes in the flowering time network. McDonald-Kreitman tests of neutrality suggested a strong excess of amino acid polymorphism when pooling across loci. This excess of replacement polymorphism across the flowering time network and a skewed derived frequency spectrum toward rare alleles for both replacement and noncoding polymorphisms relative to synonymous changes is consistent with a large class of deleterious polymorphisms segregating in these genes. Assuming selective neutrality of synonymous changes, we estimate that approximately 30% of amino acid polymorphisms are deleterious. Evidence of adaptive substitution is less prominent in our analysis. The photoperiod regulatory gene, CO, and a gibberellic acid transcription factor, AtMYB33, show evidence of adaptive fixation of amino acid mutations. A test for extended haplotypes revealed no examples of flowering time alleles with haplotypes comparable in length to those associated with the null fri(Col) allele reported previously. This suggests that the FRI gene likely has a uniquely intense or recent history of selection among the flowering time genes considered here. Although there is some evidence for adaptive evolution in these life-history genes, it appears that slightly deleterious polymorphisms are a major component of natural molecular variation in the flowering time network of A. thaliana.

  15. Biochemical function of typical and variant Arabidopsis thaliana U-box E3 ubiquitin-protein ligases.

    PubMed

    Wiborg, Jakob; O'Shea, Charlotte; Skriver, Karen

    2008-08-01

    The variance of the U-box domain in 64 Arabidopsis thaliana (thale cress) E3s (ubiquitin-protein ligases) was used to examine the interactions between E3s and E2s (ubiquitin-conjugating enzymes). E2s and E3s are components of the ubiquitin protein degradation pathway. Seven U-box proteins were analysed for their ability to ubiquitinate proteins in vitro in co-operation with different E2s. All U-box domains exhibited ubiquitination activity and interacted productively with UBC4/5-type E2s. Three and four of the U-box domains mediated ubiquitin addition in the presence of UBC13 and UBC7 E2s respectively, but no productive interaction was observed with the UBC15 E2 tested. The activity of AtPUB54 [Arabidopsis thaliana (thale cress) plant U-box 54 protein] was dependent on Trp(266) in the E2-binding cleft, and the E2 selectivity was changed by substitution of this position. The function of the distant U-box protein, AtPUB49, representing a large family of eukaryotic proteins containing a U-box linked to a cyclophilin-like peptidyl-prolyl cis-trans isomerase domain, was characterized biochemically. AtPUB49 functioned both as a prolyl isomerase and a chaperone by catalysing cis-trans isomerization of peptidyl-prolyl bonds and dissolving protein aggregates. In conclusion, both typical and atypical Arabidopsis U-box proteins were active E3s. The overlap in the E3/E2 selectivity suggests that in vivo specificity is not determined only by the E3-E2 interactions, but also by other parameters, e.g. co-existence or interactions with additional domains. The biochemical functions of AtPUB49 suggest that the protein can be involved in folding or degradation of protein substrates. Similar functions can also be retained within a protein complex with separate chaperone and U-box proteins.

  16. Minimal influence of G-protein null mutations on ozone-induced changes in gene expression, foliar injury, gas exchange and peroxidase activity in Arabidopsis thaliana L

    PubMed Central

    Booker, Fitzgerald; Burkey, Kent; Morgan, Patrick; Fiscus, Edwin; Jones, Alan

    2016-01-01

    Ozone (O3) uptake by plants leads to an increase in reactive oxygen species (ROS) in the intercellular space of leaves and induces signalling processes reported to involve the membrane-bound heterotrimeric G-protein complex. Therefore, potential G-protein-mediated response mechanisms to O3 were compared between Arabidopsis thaliana L. lines with null mutations in the α- and β-subunits (gpa1-4, agb1-2 and gpa1-4/agb1-2) and Col-0 wild-type plants. Plants were treated with a range of O3 concentrations (5, 125, 175 and 300 nL L−1) for 1 and 2 d in controlled environment chambers. Transcript levels of GPA1, AGB1 and RGS1 transiently increased in Col-0 exposed to 125 nL L−1 O3 compared with the 5 nL L−1 control treatment. However, silencing of α and β G-protein genes resulted in little alteration of many processes associated with O3 injury, including the induction of ROS-signalling genes, increased leaf tissue ion leakage, decreased net photosynthesis and stomatal conductance, and increased peroxidase activity, especially in the leaf apoplast. These results indicated that many responses to O3 stress at physiological levels were not detectably influenced by α and β G-proteins. PMID:21988569

  17. The QQS orphan gene of Arabidopsis modulates carbon and nitrogen allocation in soybean

    PubMed Central

    Li, Ling; Wurtele, Eve Syrkin

    2015-01-01

    The genome of each species contains as high as 8% of genes that are uniquely present in that species. Little is known about the functional significance of these so-called species specific or orphan genes. The Arabidopsis thaliana gene Qua-Quine Starch (QQS) is species specific. Here, we show that altering QQS expression in Arabidopsis affects carbon partitioning to both starch and protein. We hypothesized QQS may be conserved in a feature other than primary sequence, and as such could function to impact composition in another species. To test the potential of QQS in affecting composition in an ectopic species, we introduced QQS into soybean. Soybean T1 lines expressing QQS have up to 80% decreased leaf starch and up to 60% increased leaf protein; T4 generation seeds from field-grown plants contain up to 13% less oil, while protein is increased by up to 18%. These data broaden the concept of QQS as a modulator of carbon and nitrogen allocation, and demonstrate that this species-specific gene can affect the seed composition of an agronomic species thought to have diverged from Arabidopsis 100 million years ago. PMID:25146936

  18. Gene expression analysis of WRKY transcription factors in Arabidopsis thaliana cell cultures during a parabolic flight

    NASA Astrophysics Data System (ADS)

    Babbick, Maren; Barjaktarović, Žarko; Hampp, Ruediger

    Plants sense gravity by specialized cells (statocytes) and adjust growth and development accordingly. It has, however, also been shown that plant cells which are not part of specialized tissues are also able to sense gravitational forces. Therefore we used undifferentiated, homogeneous cell cultures of Arabidopsis thaliana (cv. Columbia) in order to identify early alterations in gene expression as a response to altered gravitational field strengths. In this contribution we report on cell cultures exposed to parabolic flights (approximately 20 sec of microgravity). For this short-term exposure study, we specifically checked for genes at the beginning of signal transduction chains, such as those coding for transcription factors (TFs). TFs are small proteins that regulate expression of their target genes by binding to specific promoter sequences. Our main focus were members of the so-called WRKY TF family. WRKY TFs are known to be involved in various physiological processes like senescence and pathogen defense. By quantifying transcriptional changes of these genes by real-time RT-PCR, we wanted to find out, how gene expression is affected by both hyperand microgravity conditions during a parabolic flight. For this purpose Arabidopsis thaliana callus cultures were metabolically quenched by the injection of RNAlater at the end of the microgravity-phase of each parabola. The data we present will show how fast changes in amounts of transcripts will occur, and to what degree the expression profiles are comparable with data obtained from exposures to hypergravity and simulated microgravity.

  19. A missense allele of KARRIKIN-INSENSITIVE2 impairs ligand-binding and downstream signaling in Arabidopsis thaliana.

    PubMed

    Lee, Inhye; Kim, Kuglae; Lee, Sumin; Lee, Seungjun; Hwang, Eunjin; Shin, Kihye; Kim, Dayoung; Choi, Jungki; Choi, Hyunmo; Cha, Jeong Seok; Kim, Hoyoung; Lee, Rin-A; Jeong, Suyeong; Kim, Jeongsik; Kim, Yumi; Nam, Hong Gil; Park, Soon-Ki; Cho, Hyun-Soo; Soh, Moon-Soo

    2018-06-27

    A smoke-derived compound, karrikin (KAR), and an endogenous but as yet unidentified KARRIKIN INSENSITIVE2 (KAI2) ligand (KL) have been identified as chemical cues in higher plants that impact on multiple aspects of growth and development. Genetic screening of light-signaling mutants in Arabidopsis thaliana has identified a mutant designated as ply2 (pleiotropic long hypocotyl2) that has pleiotropic light-response defects. In this study, we used positional cloning to identify the molecular lesion of ply2 as a missense mutation of KAI2/HYPOSENSITIVE TO LIGHT, which causes a single amino acid substitution, Ala219Val. Physiological analysis and genetic epistasis analysis with the KL-signaling components MORE AXILLARY GROWTH2 (MAX2) and SUPPRESSOR OF MAX2 1 suggested that the pleiotropic phenotypes of the ply2 mutant can be ascribed to a defect in KL-signaling. Molecular and biochemical analyses revealed that the mutant KAI2ply2 protein is impaired in its ligand-binding activity. In support of this conclusion, X-ray crystallography studies suggested that the KAI2ply2 mutation not only results in a narrowed entrance gate for the ligand but also alters the structural flexibility of the helical lid domains. We discuss the structural implications of the Ala219 residue with regard to ligand-specific binding and signaling of KAI2, together with potential functions of KL-signaling in the context of the light-regulatory network in Arabidopsis thaliana.

  20. Single feature polymorphism (SFP)-based selective sweep identification and association mapping of growth-related metabolic traits in Arabidopsis thaliana

    PubMed Central

    2010-01-01

    Background Natural accessions of Arabidopsis thaliana are characterized by a high level of phenotypic variation that can be used to investigate the extent and mode of selection on the primary metabolic traits. A collection of 54 A. thaliana natural accession-derived lines were subjected to deep genotyping through Single Feature Polymorphism (SFP) detection via genomic DNA hybridization to Arabidopsis Tiling 1.0 Arrays for the detection of selective sweeps, and identification of associations between sweep regions and growth-related metabolic traits. Results A total of 1,072,557 high-quality SFPs were detected and indications for 3,943 deletions and 1,007 duplications were obtained. A significantly lower than expected SFP frequency was observed in protein-, rRNA-, and tRNA-coding regions and in non-repetitive intergenic regions, while pseudogenes, transposons, and non-coding RNA genes are enriched with SFPs. Gene families involved in plant defence or in signalling were identified as highly polymorphic, while several other families including transcription factors are depleted of SFPs. 198 significant associations between metabolic genes and 9 metabolic and growth-related phenotypic traits were detected with annotation hinting at the nature of the relationship. Five significant selective sweep regions were also detected of which one associated significantly with a metabolic trait. Conclusions We generated a high density polymorphism map for 54 A. thaliana accessions that highlights the variability of resistance genes across geographic ranges and used it to identify selective sweeps and associations between metabolic genes and metabolic phenotypes. Several associations show a clear biological relationship, while many remain requiring further investigation. PMID:20302660

  1. VOZ; isolation and characterization of novel vascular plant transcription factors with a one-zinc finger from Arabidopsis thaliana.

    PubMed

    Mitsuda, Nobutaka; Hisabori, Toru; Takeyasu, Kunio; Sato, Masa H

    2004-07-01

    A 38-bp pollen-specific cis-acting region of the AVP1 gene is involved in the expression of the Arabidopsis thaliana V-PPase during pollen development. Here, we report the isolation and structural characterization of AtVOZ1 and AtVOZ2, novel transcription factors that bind to the 38-bp cis-acting region of A. thaliana V-PPase gene, AVP1. AtVOZ1 and AtVOZ2 show 53% amino acid sequence similarity. Homologs of AtVOZ1 and AtVOZ2 are found in various vascular plants as well as a moss, Physcomitrella patens. Promoter-beta-glucuronidase reporter analysis shows that AtVOZ1 is specifically expressed in the phloem tissue and AtVOZ2 is strongly expressed in the root. In vivo transient effector-reporter analysis in A. thaliana suspension-cultured cells demonstrates that AtVOZ1 and AtVOZ2 function as transcriptional activators in the Arabidopsis cell. Two conserved regions termed Domain-A and Domain-B were identified from an alignment of AtVOZ proteins and their homologs of O. sativa and P. patens. AtVOZ2 binds as a dimer to the specific palindromic sequence, GCGTNx7ACGC, with Domain-B, which is comprised of a functional novel zinc coordinating motif and a conserved basic region. Domain-B is shown to function as both the DNA-binding and the dimerization domains of AtVOZ2. From highly the conservative nature among all identified VOZ proteins, we conclude that Domain-B is responsible for the DNA binding and dimerization of all VOZ-family proteins and designate it as the VOZ-domain.

  2. Genome-wide comparative analysis of NBS-encoding genes between Brassica species and Arabidopsis thaliana.

    PubMed

    Yu, Jingyin; Tehrim, Sadia; Zhang, Fengqi; Tong, Chaobo; Huang, Junyan; Cheng, Xiaohui; Dong, Caihua; Zhou, Yanqiu; Qin, Rui; Hua, Wei; Liu, Shengyi

    2014-01-03

    Plant disease resistance (R) genes with the nucleotide binding site (NBS) play an important role in offering resistance to pathogens. The availability of complete genome sequences of Brassica oleracea and Brassica rapa provides an important opportunity for researchers to identify and characterize NBS-encoding R genes in Brassica species and to compare with analogues in Arabidopsis thaliana based on a comparative genomics approach. However, little is known about the evolutionary fate of NBS-encoding genes in the Brassica lineage after split from A. thaliana. Here we present genome-wide analysis of NBS-encoding genes in B. oleracea, B. rapa and A. thaliana. Through the employment of HMM search and manual curation, we identified 157, 206 and 167 NBS-encoding genes in B. oleracea, B. rapa and A. thaliana genomes, respectively. Phylogenetic analysis among 3 species classified NBS-encoding genes into 6 subgroups. Tandem duplication and whole genome triplication (WGT) analyses revealed that after WGT of the Brassica ancestor, NBS-encoding homologous gene pairs on triplicated regions in Brassica ancestor were deleted or lost quickly, but NBS-encoding genes in Brassica species experienced species-specific gene amplification by tandem duplication after divergence of B. rapa and B. oleracea. Expression profiling of NBS-encoding orthologous gene pairs indicated the differential expression pattern of retained orthologous gene copies in B. oleracea and B. rapa. Furthermore, evolutionary analysis of CNL type NBS-encoding orthologous gene pairs among 3 species suggested that orthologous genes in B. rapa species have undergone stronger negative selection than those in B .oleracea species. But for TNL type, there are no significant differences in the orthologous gene pairs between the two species. This study is first identification and characterization of NBS-encoding genes in B. rapa and B. oleracea based on whole genome sequences. Through tandem duplication and whole genome

  3. Root Architecture Diversity and Meristem Dynamics in Different Populations of Arabidopsis thaliana

    PubMed Central

    Aceves-García, Pamela; Álvarez-Buylla, Elena R.; Garay-Arroyo, Adriana; García-Ponce, Berenice; Muñoz, Rodrigo; Sánchez, María de la Paz

    2016-01-01

    Arabidopsis thaliana has been an excellent model system for molecular genetic approaches to development and physiology. More recently, the potential of studying various accessions collected from diverse habitats has been started to exploit. Col-0 has been the best-studied accession but we now know that several traits show significant divergences among them. In this work, we focused in the root that has become a key system for development. We studied root architecture and growth dynamics of 12 Arabidopsis accessions. Our data reveal a wide variability in root architecture and root length among accessions. We also found variability in the root apical meristem (RAM), explained mainly by cell size at the RAM transition domain and possibly by peculiar forms of organization at the stem cell niche in some accessions. Contrary to Col-0 reports, in some accessions the RAM size not always explains the variations in the root length; indicating that elongated cell size could be more relevant in the determination of root length than the RAM size itself. This study contributes to investigations dealing with understanding the molecular and cellular basis of phenotypic variation, the role of plasticity on adaptation, and the developmental mechanisms that may restrict phenotypic variation in response to contrasting environmental conditions. PMID:27379140

  4. Root Architecture Diversity and Meristem Dynamics in Different Populations of Arabidopsis thaliana.

    PubMed

    Aceves-García, Pamela; Álvarez-Buylla, Elena R; Garay-Arroyo, Adriana; García-Ponce, Berenice; Muñoz, Rodrigo; Sánchez, María de la Paz

    2016-01-01

    Arabidopsis thaliana has been an excellent model system for molecular genetic approaches to development and physiology. More recently, the potential of studying various accessions collected from diverse habitats has been started to exploit. Col-0 has been the best-studied accession but we now know that several traits show significant divergences among them. In this work, we focused in the root that has become a key system for development. We studied root architecture and growth dynamics of 12 Arabidopsis accessions. Our data reveal a wide variability in root architecture and root length among accessions. We also found variability in the root apical meristem (RAM), explained mainly by cell size at the RAM transition domain and possibly by peculiar forms of organization at the stem cell niche in some accessions. Contrary to Col-0 reports, in some accessions the RAM size not always explains the variations in the root length; indicating that elongated cell size could be more relevant in the determination of root length than the RAM size itself. This study contributes to investigations dealing with understanding the molecular and cellular basis of phenotypic variation, the role of plasticity on adaptation, and the developmental mechanisms that may restrict phenotypic variation in response to contrasting environmental conditions.

  5. Influence of hook position on phototropic and gravitropic curvature by etiolated hypocotyls of Arabidopsis thaliana

    NASA Technical Reports Server (NTRS)

    Khurana, J. P.; Best, T. R.; Poff, K. L.

    1989-01-01

    Phototropic and gravitropic curvature by hypocotyls of Arabidopsis thaliana is minimal when the side of the hook with the cotyledons attached is positioned toward the direction of tropistic curvature, and maximal when that side of the hook is positioned away from the direction of tropistic curvature. Based on these data, it is proposed that the position of the hook with attached cotyledons affects curvature and not stimulus perception. A randomly oriented population of plants exhibited considerable heterogeneity in tropistic curvature. This heterogeneity arises at least in part from the dependence of curvature on the position of the hook.

  6. Influence of hook position on phototropic and gravitropic curvature by etiolated hypocotyls of Arabidopsis thaliana.

    PubMed

    Khurana, J P; Best, T R; Poff, K L

    1989-01-01

    Phototropic and gravitropic curvature by hypocotyls of Arabidopsis thaliana is minimal when the side of the hook with the cotyledons attached is positioned toward the direction of tropistic curvature, and maximal when that side of the hook is positioned away from the direction of tropistic curvature. Based on these data, it is proposed that the position of the hook with attached cotyledons affects curvature and not stimulus perception. A randomly oriented population of plants exhibited considerable heterogeneity in tropistic curvature. This heterogeneity arises at least in part from the dependence of curvature on the position of the hook.

  7. Genome-wide analysis of mutations in mutant lineages selected following fast-neutron irradiation mutagenesis of Arabidopsis thaliana

    PubMed Central

    Belfield, Eric J.; Gan, Xiangchao; Mithani, Aziz; Brown, Carly; Jiang, Caifu; Franklin, Keara; Alvey, Elizabeth; Wibowo, Anjar; Jung, Marko; Bailey, Kit; Kalwani, Sharan; Ragoussis, Jiannis; Mott, Richard; Harberd, Nicholas P.

    2012-01-01

    Ionizing radiation has long been known to induce heritable mutagenic change in DNA sequence. However, the genome-wide effect of radiation is not well understood. Here we report the molecular properties and frequency of mutations in phenotypically selected mutant lines isolated following exposure of the genetic model flowering plant Arabidopsis thaliana to fast neutrons (FNs). Previous studies suggested that FNs predominantly induce deletions longer than a kilobase in A. thaliana. However, we found a higher frequency of single base substitution than deletion mutations. While the overall frequency and molecular spectrum of fast-neutron (FN)–induced single base substitutions differed substantially from those of “background” mutations arising spontaneously in laboratory-grown plants, G:C>A:T transitions were favored in both. We found that FN-induced G:C>A:T transitions were concentrated at pyrimidine dinucleotide sites, suggesting that FNs promote the formation of mutational covalent linkages between adjacent pyrimidine residues. In addition, we found that FNs induced more single base than large deletions, and that these single base deletions were possibly caused by replication slippage. Our observations provide an initial picture of the genome-wide molecular profile of mutations induced in A. thaliana by FN irradiation and are particularly informative of the nature and extent of genome-wide mutation in lines selected on the basis of mutant phenotypes from FN-mutagenized A. thaliana populations. PMID:22499668

  8. Novel triterpene oxidizing activity of Arabidopsis thaliana CYP716A subfamily enzymes.

    PubMed

    Yasumoto, Shuhei; Fukushima, Ery O; Seki, Hikaru; Muranaka, Toshiya

    2016-02-01

    Triterpenoids have diverse chemical structures and bioactivities. Cytochrome P450 monooxygenases play a key role in their structural diversification. In higher plants, CYP716A subfamily enzymes are triterpene oxidases. In this study, Arabidopsis thaliana CYP716A1 and CYP716A2 were characterized by heterologously expressing them in simple triterpene-producing yeast strains. In contrast to the C-28 oxidative activity of CYP716A1 shown in several CYP716A subfamily enzymes, remarkably, CYP716A2 displayed 22α-hydroxylation activity against α-amyrin that has not been previously reported, which produces the cytotoxic triterpenoid, 22α-hydroxy-α-amyrin. Our results contribute to the enrichment of the molecular toolbox that allows for the combinatorial biosynthesis of diverse triterpenoids. © 2016 Federation of European Biochemical Societies.

  9. phenoVein—A Tool for Leaf Vein Segmentation and Analysis1[OPEN

    PubMed Central

    Pflugfelder, Daniel; Huber, Gregor; Scharr, Hanno; Hülskamp, Martin; Koornneef, Maarten; Jahnke, Siegfried

    2015-01-01

    Precise measurements of leaf vein traits are an important aspect of plant phenotyping for ecological and genetic research. Here, we present a powerful and user-friendly image analysis tool named phenoVein. It is dedicated to automated segmenting and analyzing of leaf veins in images acquired with different imaging modalities (microscope, macrophotography, etc.), including options for comfortable manual correction. Advanced image filtering emphasizes veins from the background and compensates for local brightness inhomogeneities. The most important traits being calculated are total vein length, vein density, piecewise vein lengths and widths, areole area, and skeleton graph statistics, like the number of branching or ending points. For the determination of vein widths, a model-based vein edge estimation approach has been implemented. Validation was performed for the measurement of vein length, vein width, and vein density of Arabidopsis (Arabidopsis thaliana), proving the reliability of phenoVein. We demonstrate the power of phenoVein on a set of previously described vein structure mutants of Arabidopsis (hemivenata, ondulata3, and asymmetric leaves2-101) compared with wild-type accessions Columbia-0 and Landsberg erecta-0. phenoVein is freely available as open-source software. PMID:26468519

  10. 3-Hydroxyisobutyrate Dehydrogenase Is Involved in Both, Valine and Isoleucine Degradation in Arabidopsis thaliana.

    PubMed

    Schertl, Peter; Danne, Lennart; Braun, Hans-Peter

    2017-09-01

    In plants, amino acid catabolism is especially relevant in metabolic stress situations (e.g. limited carbohydrate availability during extended darkness). Under these conditions, amino acids are used as alternative substrates for respiration. Complete oxidation of the branched-chain amino acids (BCAAs) leucine, isoleucine (Ile), and valine (Val) in the mitochondria efficiently allows the formation of ATP by oxidative phosphorylation. However, the metabolic pathways for BCAA breakdown are largely unknown so far in plants. A systematic search for Arabidopsis ( Arabidopsis thaliana ) genes encoding proteins resembling enzymes involved in BCAA catabolism in animals, fungi, and bacteria as well as proteomic analyses of mitochondrial fractions from Arabidopsis allowed the identification of a putative 3-hydroxyisobutyrate dehydrogenase, AtHDH1 (At4g20930), involved in Val degradation. Systematic substrate screening analyses revealed that the protein uses 3-hydroxyisobutyrate but additionally 3-hydroxypropionate as substrates. This points to a role of the enzyme not only in Val but possibly also in Ile metabolism. At4g20930 knockdown plants were characterized to test this conclusion. Root toxicity assays revealed increased root growth inhibition of the mutants if cultivated in the presence of Val or Ile but not in the presence of leucine. We conclude that AtHDH1 has a dual role in BCAA metabolism in plants. © 2017 American Society of Plant Biologists. All Rights Reserved.

  11. Proteomic analysis of Arabidopsis thaliana (L.) Heynh responses to a generalist sucking pest (Myzus persicae Sulzer).

    PubMed

    Truong, D-H; Bauwens, J; Delaplace, P; Mazzucchelli, G; Lognay, G; Francis, F

    2015-11-01

    Herbivorous insects can cause severe cellular changes to plant foliage following infestations, depending on feeding behaviour. Here, a proteomic study was conducted to investigate the influence of green peach aphid (Myzus persicae Sulzer) as a polyphagous pest on the defence response of Arabidopsis thaliana (L.) Heynh after aphid colony establishment on the host plant (3 days). Analysis of about 574 protein spots on 2-DE gels revealed 31 differentially expressed protein spots. Twenty out of these 31 differential proteins were selected for analysis by mass spectrometry. In 12 of the 20 analysed spots, we identified seven and nine proteins using MALDI-TOF-MS and LC-ESI-MS/MS, respectively. Of the analysed spots, 25% contain two proteins. Different metabolic pathways were modulated in Arabidopsis leaves according to aphid feeding: most corresponded to carbohydrate, amino acid and energy metabolism, photosynthesis, defence response and translation. This paper has established a survey of early alterations induced in the proteome of Arabidopsis by M. persicae aphids. It provides valuable insights into the complex responses of plants to biological stress, particularly for herbivorous insects with sucking feeding behaviour. © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.

  12. Quantitative analysis of microtubule orientation in interdigitated leaf pavement cells

    PubMed Central

    Akita, Kae; Higaki, Takumi; Kutsuna, Natsumaro; Hasezawa, Seiichiro

    2015-01-01

    Leaf pavement cells are shaped like a jigsaw puzzle in most dicotyledon species. Molecular genetic studies have identified several genes required for pavement cells morphogenesis and proposed that microtubules play crucial roles in the interdigitation of pavement cells. In this study, we performed quantitative analysis of cortical microtubule orientation in leaf pavement cells in Arabidopsis thaliana. We captured confocal images of cortical microtubules in cotyledon leaf epidermis expressing GFP-tubulinβ and quantitatively evaluated the microtubule orientations relative to the pavement cell growth axis using original image processing techniques. Our results showed that microtubules kept parallel orientations to the growth axis during pavement cell growth. In addition, we showed that immersion treatment of seed cotyledons in solutions containing tubulin polymerization and depolymerization inhibitors decreased pavement cell complexity. Treatment with oryzalin and colchicine inhibited the symmetric division of guard mother cells. PMID:26039484

  13. Quantitative analysis of microtubule orientation in interdigitated leaf pavement cells.

    PubMed

    Akita, Kae; Higaki, Takumi; Kutsuna, Natsumaro; Hasezawa, Seiichiro

    2015-01-01

    Leaf pavement cells are shaped like a jigsaw puzzle in most dicotyledon species. Molecular genetic studies have identified several genes required for pavement cells morphogenesis and proposed that microtubules play crucial roles in the interdigitation of pavement cells. In this study, we performed quantitative analysis of cortical microtubule orientation in leaf pavement cells in Arabidopsis thaliana. We captured confocal images of cortical microtubules in cotyledon leaf epidermis expressing GFP-tubulinβ and quantitatively evaluated the microtubule orientations relative to the pavement cell growth axis using original image processing techniques. Our results showed that microtubules kept parallel orientations to the growth axis during pavement cell growth. In addition, we showed that immersion treatment of seed cotyledons in solutions containing tubulin polymerization and depolymerization inhibitors decreased pavement cell complexity. Treatment with oryzalin and colchicine inhibited the symmetric division of guard mother cells.

  14. Genome-wide survey of DNA-binding proteins in Arabidopsis thaliana: analysis of distribution and functions.

    PubMed

    Malhotra, Sony; Sowdhamini, Ramanathan

    2013-08-01

    The interaction of proteins with their respective DNA targets is known to control many high-fidelity cellular processes. Performing a comprehensive survey of the sequenced genomes for DNA-binding proteins (DBPs) will help in understanding their distribution and the associated functions in a particular genome. Availability of fully sequenced genome of Arabidopsis thaliana enables the review of distribution of DBPs in this model plant genome. We used profiles of both structure and sequence-based DNA-binding families, derived from PDB and PFam databases, to perform the survey. This resulted in 4471 proteins, identified as DNA-binding in Arabidopsis genome, which are distributed across 300 different PFam families. Apart from several plant-specific DNA-binding families, certain RING fingers and leucine zippers also had high representation. Our search protocol helped to assign DNA-binding property to several proteins that were previously marked as unknown, putative or hypothetical in function. The distribution of Arabidopsis genes having a role in plant DNA repair were particularly studied and noted for their functional mapping. The functions observed to be overrepresented in the plant genome harbour DNA-3-methyladenine glycosylase activity, alkylbase DNA N-glycosylase activity and DNA-(apurinic or apyrimidinic site) lyase activity, suggesting their role in specialized functions such as gene regulation and DNA repair.

  15. Study of oxidative stress related responses induced in Arabidopsis thaliana following mixed exposure to uranium and cadmium.

    PubMed

    Vanhoudt, Nathalie; Vandenhove, Hildegarde; Horemans, Nele; Wannijn, Jean; Bujanic, Andelko; Vangronsveld, Jaco; Cuypers, Ann

    2010-01-01

    In this study, toxicity effects in plants of uranium in a binary pollution condition were investigated by studying biological responses and unraveling oxidative stress related mechanisms in Arabidopsis thaliana seedlings, grown on hydroponics and exposed for 3 days to 10 μM uranium in combination with 5 μM cadmium. While uranium mostly accumulated in the roots with very low root-to-shoot transport, cadmium was taken up less by the roots but showed higher translocation to the shoots. Under mixed exposure, cadmium influenced uranium uptake highly but not the other way round resulting in a doubled uranium concentration in the roots. Under our mixed exposure conditions, it is clear that micronutrient concentrations in the roots are strongly influenced by addition of cadmium as a second stressor, while leaf macronutrient concentrations are mostly influenced by uranium. Oxidative stress related responses are highly affected by cadmium while uranium influence is more limited. Hereby, an important role was attributed to the ascorbate redox balance together with glutathione as both metabolites, but more explicitly for ascorbate, increased their reduced form, indicating an important defense and regulatory function. While for roots, based on an increase in FSD1 gene expression, oxidative stress was suggested to be superoxide induced, in leaves on the other hand, hydrogen peroxide related genes were mostly altered. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

  16. Changes in soluble sugar, starch, and alcohol dehydrogenase in Arabidopsis thaliana exposed to N2 diluted atmospheres

    NASA Technical Reports Server (NTRS)

    Porterfield, D. M.; Crispi, M. L.; Musgrave, M. E.

    1997-01-01

    Proper exchange of atmospheric gases is important for normal root and shoot metabolism in plants. This study was conducted to determine how restricted air supply affects foliar carbohydrates, while using the marker enzyme alcohol dehydrogenase (ADH) to report on the oxygenation status of the rootzone. Fourteen-day-old Arabidopsis thaliana (L.) Heynh. plants grown singly in 7-ml tubes containing agarified nutrient medium were placed in coupled Magenta vessels and exposed for six days to either ambient air or one of six different air/nitrogen dilutions. Redox potential of the agar medium was measured immediately after harvesting and freezing leaf tissue, and then root systems were quickly extracted from the agar and frozen for subsequent analyses. Redox potential measurements indicated that this series of gas mixtures produced a transition from hypoxia to anoxia in the root zones. Root ADH activity increased at higher rates as the redox potential neared anoxic levels. In contrast, ADH mRNA expression quickly neared its maximum as the medium became hypoxic and showed little further increase as it became anoxic. Foliar carbohydrate levels increased 1.5- to 2-fold with decreased availability of metabolic gases, with starch increasing at higher concentrations of air than soluble carbohydrate. The results serve as a model for plant performance under microgravity conditions, where absence of convective air movement prevents replenishment of metabolic gases.

  17. Canopy light cues affect emission of constitutive and methyl jasmonate-induced volatile organic compounds in Arabidopsis thaliana.

    PubMed

    Kegge, Wouter; Weldegergis, Berhane T; Soler, Roxina; Vergeer-Van Eijk, Marleen; Dicke, Marcel; Voesenek, Laurentius A C J; Pierik, Ronald

    2013-11-01

    The effects of plant competition for light on the emission of plant volatile organic compounds (VOCs) were studied by investigating how different light qualities that occur in dense vegetation affect the emission of constitutive and methyl-jasmonate-induced VOCs. Arabidopsis thaliana Columbia (Col-0) plants and Pieris brassicae caterpillars were used as a biological system to study the effects of light quality manipulations on VOC emissions and attraction of herbivores. VOCs were analysed using gas chromatography-mass spectrometry and the effects of light quality, notably the red : far red light ratio (R : FR), on expression of genes associated with VOC production were studied using reverse transcriptase-quantitative PCR. The emissions of both constitutive and methyl-jasmonate-induced green leaf volatiles and terpenoids were partially suppressed under low R : FR and severe shading conditions. Accordingly, the VOC-based preference of neonates of the specialist lepidopteran herbivore P. brassicae was significantly affected by the R : FR ratio. We conclude that VOC-mediated interactions among plants and between plants and organisms at higher trophic levels probably depend on light alterations caused by nearby vegetation. Studies on plant-plant and plant-insect interactions through VOCs should take into account the light quality within dense stands when extrapolating to natural and agricultural field conditions. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  18. Identification and Evolution of Functional Alleles of the Previously Described Pollen Specific Myrosinase Pseudogene AtTGG6 in Arabidopsis thaliana.

    PubMed

    Fu, Lili; Han, Bingying; Tan, Deguan; Wang, Meng; Ding, Mei; Zhang, Jiaming

    2016-02-22

    Myrosinases are β-thioglucoside glucohydrolases and serve as defense mechanisms against insect pests and pathogens by producing toxic compounds. AtTGG6 in Arabidopsis thaliana was previously reported to be a myrosinase pseudogene but specifically expressed in pollen. However, we found that AlTGG6, an ortholog to AtTGG6 in A. lyrata (an outcrossing relative of A. thaliana) was functional, suggesting that functional AtTGG6 alleles may still exist in A. thaliana. AtTGG6 alleles in 29 A. thaliana ecotypes were cloned and sequenced. Results indicate that ten alleles were functional and encoded Myr II type myrosinase of 512 amino acids, and myrosinase activity was confirmed by overexpressing AtTGG6 in Pichia pastoris. However, the 19 other ecotypes had disabled alleles with highly polymorphic frame-shift mutations and diversified sequences. Thirteen frame-shift mutation types were identified, which occurred independently many times in the evolutionary history within a few thousand years. The functional allele was expressed specifically in pollen similar to the disabled alleles but at a higher expression level, suggesting its role in defense of pollen against insect pests such as pollen beetles. However, the defense function may have become less critical after A. thaliana evolved to self-fertilization, and thus resulted in loss of function in most ecotypes.

  19. Arabidopsis thaliana GYRB3 Does Not Encode a DNA Gyrase Subunit

    PubMed Central

    Evans-Roberts, Katherine M.; Breuer, Christian; Wall, Melisa K.; Sugimoto-Shirasu, Keiko; Maxwell, Anthony

    2010-01-01

    Background DNA topoisomerases are enzymes that control the topology of DNA in all cells. DNA gyrase is unique among the topoisomerases in that it is the only enzyme that can actively supercoil DNA using the free energy of ATP hydrolysis. Until recently gyrase was thought to be unique to bacteria, but has now been discovered in plants. The genome of the model plant, Arabidopsis thaliana, is predicted to encode four gyrase subunits: AtGyrA, AtGyrB1, AtGyrB2 and AtGyrB3. Methodology/Principal Findings We found, contrary to previous data, that AtGyrB3 is not essential to the survival of A. thaliana. Bioinformatic analysis suggests AtGyrB3 is considerably shorter than other gyrase B subunits, lacking part of the ATPase domain and other key motifs found in all type II topoisomerases; but it does contain a putative DNA-binding domain. Partially purified AtGyrB3 cannot bind E. coli GyrA or support supercoiling. AtGyrB3 cannot complement an E. coli gyrB temperature-sensitive strain, whereas AtGyrB2 can. Yeast two-hybrid analysis suggests that AtGyrB3 cannot bind to AtGyrA or form a dimer. Conclusions/Significance These data strongly suggest that AtGyrB3 is not a gyrase subunit but has another unknown function. One possibility is that it is a nuclear protein with a role in meiosis in pollen. PMID:20360860

  20. Arabidopsis thaliana GYRB3 does not encode a DNA gyrase subunit.

    PubMed

    Evans-Roberts, Katherine M; Breuer, Christian; Wall, Melisa K; Sugimoto-Shirasu, Keiko; Maxwell, Anthony

    2010-03-26

    DNA topoisomerases are enzymes that control the topology of DNA in all cells. DNA gyrase is unique among the topoisomerases in that it is the only enzyme that can actively supercoil DNA using the free energy of ATP hydrolysis. Until recently gyrase was thought to be unique to bacteria, but has now been discovered in plants. The genome of the model plant, Arabidopsis thaliana, is predicted to encode four gyrase subunits: AtGyrA, AtGyrB1, AtGyrB2 and AtGyrB3. We found, contrary to previous data, that AtGyrB3 is not essential to the survival of A. thaliana. Bioinformatic analysis suggests AtGyrB3 is considerably shorter than other gyrase B subunits, lacking part of the ATPase domain and other key motifs found in all type II topoisomerases; but it does contain a putative DNA-binding domain. Partially purified AtGyrB3 cannot bind E. coli GyrA or support supercoiling. AtGyrB3 cannot complement an E. coli gyrB temperature-sensitive strain, whereas AtGyrB2 can. Yeast two-hybrid analysis suggests that AtGyrB3 cannot bind to AtGyrA or form a dimer. These data strongly suggest that AtGyrB3 is not a gyrase subunit but has another unknown function. One possibility is that it is a nuclear protein with a role in meiosis in pollen.

  1. PtrWRKY73, a salicylic acid-inducible poplar WRKY transcription factor, is involved in disease resistance in Arabidopsis thaliana.

    PubMed

    Duan, Yanjiao; Jiang, Yuanzhong; Ye, Shenglong; Karim, Abdul; Ling, Zhengyi; He, Yunqiu; Yang, Siqi; Luo, Keming

    2015-05-01

    A salicylic acid-inducible WRKY gene, PtrWRKY73, from Populus trichocarpa , was isolated and characterized. Overexpression of PtrWRKY73 in Arabidopsis thaliana increased resistance to biotrophic pathogens but reduced resistance against necrotrophic pathogens. WRKY transcription factors are commonly involved in plant defense responses. However, limited information is available about the roles of the WRKY genes in poplar defense. In this study, we isolated a salicylic acid (SA)-inducible WRKY gene, PtrWRKY73, from Populus trichocarpa, belonging to group I family and containing two WRKY domains, a D domain and an SP cluster. PtrWRKY73 was expressed predominantly in roots, old leaves, sprouts and stems, especially in phloem and its expression was induced in response to treatment with exogenous SA. PtrWRKY73 was localized to the nucleus of plant cells and exhibited transcriptional activation. Overexpression of PtrWRKY73 in Arabidopsis thaliana resulted in increased resistance to a virulent strain of the bacterial pathogen Pseudomonas syringae (PstDC3000), but more sensitivity to the necrotrophic fungal pathogen Botrytis cinerea. The SA-mediated defense-associated genes, such as PR1, PR2 and PAD4, were markedly up-regulated in transgenic plants overexpressing PtrWRKY73. Arabidopsis non-expressor of PR1 (NPR1) was not affected, whereas a defense-related gene PAL4 had reduced in PtrWRKY73 overexpressor plants. Together, these results indicated that PtrWRKY73 plays a positive role in plant resistance to biotrophic pathogens but a negative effect on resistance against necrotrophic pathogens.

  2. A Method of Accounting for Enzyme Costs in Flux Balance Analysis Reveals Alternative Pathways and Metabolite Stores in an Illuminated Arabidopsis Leaf.

    PubMed

    Cheung, C Y Maurice; Ratcliffe, R George; Sweetlove, Lee J

    2015-11-01

    Flux balance analysis of plant metabolism is an established method for predicting metabolic flux phenotypes and for exploring the way in which the plant metabolic network delivers specific outcomes in different cell types, tissues, and temporal phases. A recurring theme is the need to explore the flexibility of the network in meeting its objectives and, in particular, to establish the extent to which alternative pathways can contribute to achieving specific outcomes. Unfortunately, predictions from conventional flux balance analysis minimize the simultaneous operation of alternative pathways, but by introducing flux-weighting factors to allow for the variable intrinsic cost of supporting each flux, it is possible to activate different pathways in individual simulations and, thus, to explore alternative pathways by averaging thousands of simulations. This new method has been applied to a diel genome-scale model of Arabidopsis (Arabidopsis thaliana) leaf metabolism to explore the flexibility of the network in meeting the metabolic requirements of the leaf in the light. This identified alternative flux modes in the Calvin-Benson cycle revealed the potential for alternative transitory carbon stores in leaves and led to predictions about the light-dependent contribution of alternative electron flow pathways and futile cycles in energy rebalancing. Notable features of the analysis include the light-dependent tradeoff between the use of carbohydrates and four-carbon organic acids as transitory storage forms and the way in which multiple pathways for the consumption of ATP and NADPH can contribute to the balancing of the requirements of photosynthetic metabolism with the energy available from photon capture. © 2015 American Society of Plant Biologists. All Rights Reserved.

  3. The Arabidopsis thaliana mobilome and its impact at the species level.

    PubMed

    Quadrana, Leandro; Bortolini Silveira, Amanda; Mayhew, George F; LeBlanc, Chantal; Martienssen, Robert A; Jeddeloh, Jeffrey A; Colot, Vincent

    2016-06-03

    Transposable elements (TEs) are powerful motors of genome evolution yet a comprehensive assessment of recent transposition activity at the species level is lacking for most organisms. Here, using genome sequencing data for 211 Arabidopsis thaliana accessions taken from across the globe, we identify thousands of recent transposition events involving half of the 326 TE families annotated in this plant species. We further show that the composition and activity of the 'mobilome' vary extensively between accessions in relation to climate and genetic factors. Moreover, TEs insert equally throughout the genome and are rapidly purged by natural selection from gene-rich regions because they frequently affect genes, in multiple ways. Remarkably, loci controlling adaptive responses to the environment are the most frequent transposition targets observed. These findings demonstrate the pervasive, species-wide impact that a rich mobilome can have and the importance of transposition as a recurrent generator of large-effect alleles.

  4. SnRK1 activates autophagy via the TOR signaling pathway in Arabidopsis thaliana

    PubMed Central

    Soto-Burgos, Junmarie

    2017-01-01

    Autophagy is a degradation process in which cells break down and recycle their cytoplasmic contents when subjected to environmental stress or during cellular remodeling. The Arabidopsis thaliana SnRK1 complex is a protein kinase that senses changes in energy levels and triggers downstream responses to enable survival. Its mammalian ortholog, AMPK, and yeast ortholog, Snf-1, activate autophagy in response to low energy conditions. We therefore hypothesized that SnRK1 may play a role in the regulation of autophagy in response to nutrient or energy deficiency in Arabidopsis. To test this hypothesis, we determined the effect of overexpression or knockout of the SnRK1 catalytic subunit KIN10 on autophagy activation by abiotic stresses, including nutrient deficiency, salt, osmotic, oxidative, and ER stress. While wild-type plants had low basal autophagy activity in control conditions, KIN10 overexpression lines had increased autophagy under these conditions, indicating activation of autophagy by SnRK1. A kin10 mutant had a basal level of autophagy under control conditions similar to wild-type plants, but activation of autophagy by most abiotic stresses was blocked, indicating that SnRK1 is required for autophagy induction by a wide variety of stress conditions. In mammals, TOR is a negative regulator of autophagy, and AMPK acts to activate autophagy both upstream of TOR, by inhibiting its activity, and in a parallel pathway. Inhibition of Arabidopsis TOR leads to activation of autophagy; inhibition of SnRK1 did not block this activation. Furthermore, an increase in SnRK1 activity was unable to induce autophagy when TOR was also activated. These results demonstrate that SnRK1 acts upstream of TOR in the activation of autophagy in Arabidopsis. PMID:28783755

  5. SnRK1 activates autophagy via the TOR signaling pathway in Arabidopsis thaliana

    DOE PAGES

    Soto-Burgos, Junmarie; Bassham, Diane C.

    2017-08-04

    Autophagy is a degradation process in which cells break down and recycle their cytoplasmic contents when subjected to environmental stress or during cellular remodeling. The Arabidopsis thaliana SnRK1 complex is a protein kinase that senses changes in energy levels and triggers downstream responses to enable survival. Its mammalian ortholog, AMPK, and yeast ortholog, Snf-1, activate autophagy in response to low energy conditions. We therefore hypothesized that SnRK1 may play a role in the regulation of autophagy in response to nutrient or energy deficiency in Arabidopsis. To test this hypothesis, we determined the effect of overexpression or knockout of the SnRK1more » catalytic subunit KIN10 on autophagy activation by abiotic stresses, including nutrient deficiency, salt, osmotic, oxidative, and ER stress. While wild-type plants had low basal autophagy activity in control conditions, KIN10 overexpression lines had increased autophagy under these conditions, indicating activation of autophagy by SnRK1. A kin10 mutant had a basal level of autophagy under control conditions similar to wild-type plants, but activation of autophagy by most abiotic stresses was blocked, indicating that SnRK1 is required for autophagy induction by a wide variety of stress conditions. In mammals, TOR is a negative regulator of autophagy, and AMPK acts to activate autophagy both upstream of TOR, by inhibiting its activity, and in a parallel pathway. Inhibition of Arabidopsis TOR leads to activation of autophagy; inhibition of SnRK1 did not block this activation. Furthermore, an increase in SnRK1 activity was unable to induce autophagy when TOR was also activated. The results presented here demonstrate that SnRK1 acts upstream of TOR in the activation of autophagy in Arabidopsis.« less

  6. SnRK1 activates autophagy via the TOR signaling pathway in Arabidopsis thaliana

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

    Soto-Burgos, Junmarie; Bassham, Diane C.

    Autophagy is a degradation process in which cells break down and recycle their cytoplasmic contents when subjected to environmental stress or during cellular remodeling. The Arabidopsis thaliana SnRK1 complex is a protein kinase that senses changes in energy levels and triggers downstream responses to enable survival. Its mammalian ortholog, AMPK, and yeast ortholog, Snf-1, activate autophagy in response to low energy conditions. We therefore hypothesized that SnRK1 may play a role in the regulation of autophagy in response to nutrient or energy deficiency in Arabidopsis. To test this hypothesis, we determined the effect of overexpression or knockout of the SnRK1more » catalytic subunit KIN10 on autophagy activation by abiotic stresses, including nutrient deficiency, salt, osmotic, oxidative, and ER stress. While wild-type plants had low basal autophagy activity in control conditions, KIN10 overexpression lines had increased autophagy under these conditions, indicating activation of autophagy by SnRK1. A kin10 mutant had a basal level of autophagy under control conditions similar to wild-type plants, but activation of autophagy by most abiotic stresses was blocked, indicating that SnRK1 is required for autophagy induction by a wide variety of stress conditions. In mammals, TOR is a negative regulator of autophagy, and AMPK acts to activate autophagy both upstream of TOR, by inhibiting its activity, and in a parallel pathway. Inhibition of Arabidopsis TOR leads to activation of autophagy; inhibition of SnRK1 did not block this activation. Furthermore, an increase in SnRK1 activity was unable to induce autophagy when TOR was also activated. The results presented here demonstrate that SnRK1 acts upstream of TOR in the activation of autophagy in Arabidopsis.« less

  7. 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.

  8. Simplified Enrichment of Plasma Membrane Proteins from Arabidopsis thaliana Seedlings Using Differential Centrifugation and Brij-58 Treatment.

    PubMed

    Collins, Carina A; Leslie, Michelle E; Peck, Scott C; Heese, Antje

    2017-01-01

    The plasma membrane (PM) forms a barrier between a plant cell and its environment. Proteins at this subcellular location play diverse and complex roles, including perception of extracellular signals to coordinate cellular changes. Analyses of PM proteins, however, are often limited by the relatively low abundance of these proteins in the total cellular protein pool. Techniques traditionally used for enrichment of PM proteins are time consuming, tedious, and require extensive optimization. Here, we provide a simple and reproducible enrichment procedure for PM proteins from Arabidopsis thaliana seedlings starting from total microsomal membranes isolated by differential centrifugation. To enrich for PM proteins, total microsomes are treated with the nonionic detergent Brij-58 to decrease the abundance of contaminating organellar proteins. This protocol combined with the genetic resources available in Arabidopsis provides a powerful tool that will enhance our understanding of proteins at the PM.

  9. The plant leaf movement analyzer (PALMA): a simple tool for the analysis of periodic cotyledon and leaf movement in Arabidopsis thaliana.

    PubMed

    Wagner, Lucas; Schmal, Christoph; Staiger, Dorothee; Danisman, Selahattin

    2017-01-01

    The analysis of circadian leaf movement rhythms is a simple yet effective method to study effects of treatments or gene mutations on the circadian clock of plants. Currently, leaf movements are analysed using time lapse photography and subsequent bioinformatics analyses of leaf movements. Programs that are used for this purpose either are able to perform one function (i.e. leaf tip detection or rhythm analysis) or their function is limited to specific computational environments. We developed a leaf movement analysis tool-PALMA-that works in command line and combines image extraction with rhythm analysis using Fast Fourier transformation and non-linear least squares fitting. We validated PALMA in both simulated time series and in experiments using the known short period mutant sensitivity to red light reduced 1 ( srr1 - 1 ). We compared PALMA with two established leaf movement analysis tools and found it to perform equally well. Finally, we tested the effect of reduced iron conditions on the leaf movement rhythms of wild type plants. Here, we found that PALMA successfully detected period lengthening under reduced iron conditions. PALMA correctly estimated the period of both simulated and real-life leaf movement experiments. As a platform-independent console-program that unites both functions needed for the analysis of circadian leaf movements it is a valid alternative to existing leaf movement analysis tools.

  10. AtRD22 and AtUSPL1, Members of the Plant-Specific BURP Domain Family Involved in Arabidopsis thaliana Drought Tolerance

    PubMed Central

    Harshavardhan, Vokkaliga Thammegowda; Van Son, Le; Seiler, Christiane; Junker, Astrid; Weigelt-Fischer, Kathleen; Klukas, Christian; Altmann, Thomas; Sreenivasulu, Nese; Bäumlein, Helmut; Kuhlmann, Markus

    2014-01-01

    Crop plants are regularly challenged by a range of environmental stresses which typically retard their growth and ultimately compromise economic yield. The stress response involves the reprogramming of approximately 4% of the transcriptome. Here, the behavior of AtRD22 and AtUSPL1, both members of the Arabidopsis thaliana BURP (BNM2, USP, RD22 and polygalacturonase isozyme) domain-containing gene family, has been characterized. Both genes are up-regulated as part of the abscisic acid (ABA) mediated moisture stress response. While AtRD22 transcript was largely restricted to the leaf, that of AtUSPL1 was more prevalent in the root. As the loss of function of either gene increased the plant's moisture stress tolerance, the implication was that their products act to suppress the drought stress response. In addition to the known involvement of AtUSPL1 in seed development, a further role in stress tolerance was demonstrated. Based on transcriptomic data and phenotype we concluded that the enhanced moisture stress tolerance of the two loss-of-function mutants is a consequence of an enhanced basal defense response. PMID:25333723

  11. Integrative analysis of Arabidopsis thaliana transcriptomics reveals intuitive splicing mechanism for circular RNA.

    PubMed

    Sun, Xiaoyong; Wang, Lin; Ding, Jiechao; Wang, Yanru; Wang, Jiansheng; Zhang, Xiaoyang; Che, Yulei; Liu, Ziwei; Zhang, Xinran; Ye, Jiazhen; Wang, Jie; Sablok, Gaurav; Deng, Zhiping; Zhao, Hongwei

    2016-10-01

    A new regulatory class of small endogenous RNAs called circular RNAs (circRNAs) has been described as miRNA sponges in animals. Using 16 Arabidopsis thaliana RNA-Seq data sets, we identified 803 circRNAs in RNase R-/non-RNase R-treated samples. The results revealed the following features: Canonical and noncanonical splicing can generate circRNAs; chloroplasts are a hotspot for circRNA generation; furthermore, limited complementary sequences exist not only in introns, but also in the sequences flanking splice sites. The latter finding suggests that multiple combinations between complementary sequences may facilitate the formation of the circular structure. Our results contribute to a better understanding of this novel class of plant circRNAs. © 2016 Federation of European Biochemical Societies.

  12. An Efficient Visual Screen for CRISPR/Cas9 Activity in Arabidopsis thaliana.

    PubMed

    Hahn, Florian; Mantegazza, Otho; Greiner, André; Hegemann, Peter; Eisenhut, Marion; Weber, Andreas P M

    2017-01-01

    The CRISPR/Cas9 system enables precision editing of the genome of the model plant Arabidopsis thaliana and likely of any other organism. Tools and methods for further developing and optimizing this widespread and versatile system in Arabidopsis would hence be welcomed. Here, we designed a generic vector system that can be used to clone any sgRNA sequence in a plant T-DNA vector containing an ubiquitously expressed Cas9 gene. With this vector, we explored two alternative marker systems for tracking Cas9-mediated gene-editing in vivo : BIALAPHOS RESISTANCE ( BAR ) and GLABROUS1 ( GL1 ). BAR confers resistance to glufosinate and is widely used as a positive selection marker; GL1 is required for the formation of trichomes. Reversion of a frameshift null BAR allele to a functional one by Cas9-mediated gene editing yielded a higher than expected number of plants that are resistant to glufosinate. Surprisingly, many of those plants did not display reversion of the BAR gene through the germline. We hypothesize that few BAR revertant cells in a highly chimeric plant likely provide system-wide resistance to glufosinate and thus we suggest that BAR is not suitable as marker for tracking Cas9-mediated gene-editing. Targeting the GL1 gene for disruption with Cas9 provided clearly visible phenotypes of partially and completely glabrous plants. 50% of the analyzed T1 plants produced descendants with a chimeric phenotype and we could recover fully homozygous plants in the T3 generation with high efficiency. We propose that targeting of GL1 is suitable for assessing and optimizing Cas9-mediated gene-editing in Arabidopsis .

  13. Citral induces auxin and ethylene-mediated malformations and arrests cell division in Arabidopsis thaliana roots.

    PubMed

    Graña, E; Sotelo, T; Díaz-Tielas, C; Araniti, F; Krasuska, U; Bogatek, R; Reigosa, M J; Sánchez-Moreiras, A M

    2013-02-01

    Citral is a linear monoterpene which is present, as a volatile component, in the essential oil of several different aromatic plants. Previous studies have demonstrated the ability of citral to alter the mitotic microtubules of plant cells, especially at low concentrations. The changes to the microtubules may be due to the compound acting directly on the treated root and coleoptile cells or to indirect action through certain phytohormones. This study, performed in Arabidopsis thaliana, analysed the short-term effects of citral on the auxin content and mitotic cells, and the long-term effects of these alterations on root development and ethylene levels. The results of this study show that citral alters auxin content and cell division and has a strong long-term disorganising effect on cell ultra-structure in A. thaliana seedlings. Its effects on cell division, the thickening of the cell wall, the reduction in intercellular communication, and the absence of root hairs confirm that citral is a strong phytotoxic compound, which has persistent effects on root development.

  14. Artificial Autopolyploidization Modifies the Tricarboxylic Acid Cycle and GABA Shunt in Arabidopsis thaliana Col-0

    NASA Astrophysics Data System (ADS)

    Vergara, Fredd; Kikuchi, Jun; Breuer, Christian

    2016-05-01

    Autopolyploidy is a process whereby the chromosome set is multiplied and it is a common phenomenon in angiosperms. Autopolyploidy is thought to be an important evolutionary force that has led to the formation of new plant species. Despite its relevance, the consequences of autopolyploidy in plant metabolism are poorly understood. This study compares the metabolic profiles of natural diploids and artificial autotetraploids of Arabidopsis thaliana Col-0. Different physiological parameters are compared between diploids and autotetraploids using nuclear magnetic resonance (NMR), elemental analysis (carbon:nitrogen balance) and quantitative real-time PCR (qRT-PCR). The main difference between diploid and autotetraploid A. thaliana Col-0 is observed in the concentration of metabolites related to the tricarboxylic acid cycle (TCA) and γ-amino butyric acid (GABA) shunt, as shown by multivariate statistical analysis of NMR spectra. qRT-PCR shows that genes related to the TCA and GABA shunt are also differentially expressed between diploids and autotetraploids following similar trends as their corresponding metabolites. Solid evidence is presented to demonstrate that autopolyploidy influences core plant metabolic processes.

  15. The Endoplasmic Reticulum Is a Reservoir for WAVE/SCAR Regulatory Complex Signaling in the Arabidopsis Leaf1[W][OA

    PubMed Central

    Zhang, Chunhua; Mallery, Eileen; Reagan, Sara; Boyko, Vitaly P.; Kotchoni, Simeon O.; Szymanski, Daniel B.

    2013-01-01

    During plant cell morphogenesis, signal transduction and cytoskeletal dynamics interact to locally organize the cytoplasm and define the geometry of cell expansion. The WAVE/SCAR (for WASP family verprolin homologous/suppressor of cyclic AMP receptor) regulatory complex (W/SRC) is an evolutionarily conserved heteromeric protein complex. Within the plant kingdom W/SRC is a broadly used effector that converts Rho-of-Plants (ROP)/Rac small GTPase signals into Actin-Related Protein2/3 and actin-dependent growth responses. Although the components and biochemistry of the W/SRC pathway are well understood, a basic understanding of how cells partition W/SRC into active and inactive pools is lacking. In this paper, we report that the endoplasmic reticulum (ER) is an important organelle for W/SRC regulation. We determined that a large intracellular pool of the core W/SRC subunit NAP1, like the known positive regulator of W/SRC, the DOCK family guanine nucleotide-exchange factor SPIKE1 (SPK1), localizes to the surface of the ER. The ER-associated NAP1 is inactive because it displays little colocalization with the actin network, and ER localization requires neither activating signals from SPK1 nor a physical association with its W/SRC-binding partner, SRA1. Our results indicate that in Arabidopsis (Arabidopsis thaliana) leaf pavement cells and trichomes, the ER is a reservoir for W/SRC signaling and may have a key role in the early steps of W/SRC assembly and/or activation. PMID:23613272

  16. The demise of chloroplast DNA in Arabidopsis.

    PubMed

    Rowan, Beth A; Oldenburg, Delene J; Bendich, Arnold J

    2004-09-01

    Although it might be expected that chloroplast DNA (cpDNA) would be stably maintained in mature leaves, we report the surprising observation that cpDNA levels decline during plastid development in Arabidopsis thaliana (Col.) until most of the leaves contain little or no DNA long before the onset of senescence. We measured the cpDNA content in developing cotyledons, rosette leaves, and cauline leaves. The amount of cpDNA per chloroplast decreases as the chloroplasts develop, reaching undetectable levels in mature leaves. In young cauline leaves, most individual molecules of cpDNA are found in complex, branched forms. In expanded cauline leaves, cpDNA is present in smaller branched forms only at the base of the leaf and is virtually absent in the distal part of the leaf. We conclude that photosynthetic activity may persist long after the demise of the cpDNA. Copyright 2004 Springer-Verlag

  17. Structural analysis of Arabidopsis thaliana nucleoside diphosphate kinase-2 for phytochrome-mediated light signaling.

    PubMed

    Im, Young Jun; Kim, Jeong-Il; Shen, Yu; Na, Young; Han, Yun-Jeong; Kim, Seong-Hee; Song, Pill-Soon; Eom, Soo Hyun

    2004-10-22

    In plants, nucleoside diphosphate kinases (NDPKs) play a key role in the signaling of both stress and light. However, little is known about the structural elements involved in their function. Of the three NDPKs (NDPK1-NDPK3) expressed in Arabidopsis thaliana, NDPK2 is involved in phytochrome-mediated signal transduction. In this study, we found that the binding of dNDP or NTP to NDPK2 strengthens the interaction significantly between activated phytochrome and NDPK2. To better understand the structural basis of the phytochrome-NDPK2 interaction, we determined the X-ray structures of NDPK1, NDPK2, and dGTP-bound NDPK2 from A.thaliana at 1.8A, 2.6A, and 2.4A, respectively. The structures showed that nucleotide binding caused a slight conformational change in NDPK2 that was confined to helices alphaA and alpha2. This suggests that the presence of nucleotide in the active site and/or the evoked conformational change contributes to the recognition of NDPK2 by activated phytochrome. In vitro binding assays showed that only NDPK2 interacted specifically with the phytochrome and the C-terminal regulatory domain of phytochrome is involved in the interaction. A domain swap experiment between NDPK1 and NDPK2 showed that the variable C-terminal region of NDPK2 is important for the activation by phytochrome. The structure of Arabidopsis NDPK1 and NDPK2 showed that the isoforms share common electrostatic surfaces at the nucleotide-binding site, but the variable C-terminal regions have distinct electrostatic charge distributions. These findings suggest that the binding of nucleotide to NDPK2 plays a regulatory role in phytochrome signaling and that the C-terminal extension of NDPK2 provides a potential binding surface for the specific interaction with phytochromes.

  18. Arabidopsis thaliana defense response to the ochratoxin A-producing strain (Aspergillus ochraceus 3.4412).

    PubMed

    Hao, Junran; Wu, Weihong; Wang, Yan; Yang, Zhuojun; Liu, Yang; Lv, Yangjun; Zhai, Yanan; Yang, Jing; Liang, Zhihong; Huang, Kunlun; Xu, Wentao

    2015-05-01

    OTA-producing strain Aspergillus ochraceus induced necrotic lesions, ROS accumulation and defense responses in Arabidopsis . Primary metabolic and defense-related proteins changed in proteomics. Ascorbate-glutathione cycle and voltage-dependent anion-selective channel proteins fluctuated. Mycotoxigenic fungi, as widespread contaminants by synthesizing mycotoxins in pre-/post-harvest infected plants and even stored commercial cereals, could usually induce plant-fungi defense responses. Notably, ochratoxin A (OTA) is a nephrotoxic, hepatotoxic, teratogenic, immunotoxic and phytotoxic mycotoxin. Herein, defense responses of model system Arabidopsis thaliana detached leaves to infection of Aspergillus ochraceus 3.4412, an OTA high-producing strain, were studied from physiological, proteomic and transcriptional perspectives. During the first 72 h after inoculation (hai), the newly formed hypersensitive responses-like lesions, decreased chlorophyll content, accumulated reactive oxygen species and upregulated defense genes expressions indicated the defense response was induced in the leaves with the possible earlier motivated jasmonic acid/ethylene signaling pathways and the later salicylic acid-related pathway. Moreover, proteomics using two-dimensional gel electrophoresis 72 hai showed 16 spots with significantly changed abundance and 13 spots corresponding to 12 unique proteins were successfully identified by MALDI-TOF/TOF MS/MS. Of these, six proteins were involved in basic metabolism and four in defense-related processes, which included glutathione-S-transferase F7, voltage-dependent anion-selective channel protein 3 (VDAC-3), osmotin-like protein OSM34 and blue copper-binding protein. Verified from proteomic and/or transcriptional perspectives, it is concluded that the primary metabolic pathways were suppressed with the ascorbate-glutathione cycle fluctuated in response to A. ochraceus and the modulation of VDACs suggested the possibility of structural damage and

  19. Control of Leaf Expansion: A Developmental Switch from Metabolics to Hydraulics1[W][OA

    PubMed Central

    Pantin, Florent; Simonneau, Thierry; Rolland, Gaëlle; Dauzat, Myriam; Muller, Bertrand

    2011-01-01

    Leaf expansion is the central process by which plants colonize space, allowing energy capture and carbon acquisition. Water and carbon emerge as main limiting factors of leaf expansion, but the literature remains controversial about their respective contributions. Here, we tested the hypothesis that the importance of hydraulics and metabolics is organized according to both dark/light fluctuations and leaf ontogeny. For this purpose, we established the developmental pattern of individual leaf expansion during days and nights in the model plant Arabidopsis (Arabidopsis thaliana). Under control conditions, decreases in leaf expansion were observed at night immediately after emergence, when starch reserves were lowest. These nocturnal decreases were strongly exaggerated in a set of starch mutants, consistent with an early carbon limitation. However, low-light treatment of wild-type plants had no influence on these early decreases, implying that expansion can be uncoupled from changes in carbon availability. From 4 d after leaf emergence onward, decreases of leaf expansion were observed in the daytime. Using mutants impaired in stomatal control of transpiration as well as plants grown under soil water deficit or high air humidity, we gathered evidence that these diurnal decreases were the signature of a hydraulic limitation that gradually set up as the leaf developed. Changes in leaf turgor were consistent with this pattern. It is concluded that during the course of leaf ontogeny, the predominant control of leaf expansion switches from metabolics to hydraulics. We suggest that the leaf is better armed to buffer variations in the former than in the latter. PMID:21474437

  20. Longitudinal trends in climate drive flowering time clines in North American Arabidopsis thaliana.

    PubMed

    Samis, Karen E; Murren, Courtney J; Bossdorf, Oliver; Donohue, Kathleen; Fenster, Charles B; Malmberg, Russell L; Purugganan, Michael D; Stinchcombe, John R

    2012-06-01

    Introduced species frequently show geographic differentiation, and when differentiation mirrors the ancestral range, it is often taken as evidence of adaptive evolution. The mouse-ear cress (Arabidopsis thaliana) was introduced to North America from Eurasia 150-200 years ago, providing an opportunity to study parallel adaptation in a genetic model organism. Here, we test for clinal variation in flowering time using 199 North American (NA) accessions of A. thaliana, and evaluate the contributions of major flowering time genes FRI, FLC, and PHYC as well as potential ecological mechanisms underlying differentiation. We find evidence for substantial within population genetic variation in quantitative traits and flowering time, and putatively adaptive longitudinal differentiation, despite low levels of variation at FRI, FLC, and PHYC and genome-wide reductions in population structure relative to Eurasian (EA) samples. The observed longitudinal cline in flowering time in North America is parallel to an EA cline, robust to the effects of population structure, and associated with geographic variation in winter precipitation and temperature. We detected major effects of FRI on quantitative traits associated with reproductive fitness, although the haplotype associated with higher fitness remains rare in North America. Collectively, our results suggest the evolution of parallel flowering time clines through novel genetic mechanisms.

  1. Putrescine accumulation in Arabidopsis thaliana transgenic lines enhances tolerance to dehydration and freezing stress

    PubMed Central

    Alet, Analía I; Sanchez, Diego H; Cuevas, Juan C; del Valle, Secundino; Altabella, Teresa; Tiburcio, Antonio F; Marco, Francisco; Ferrando, Alejandro; Espasandín, Fabiana D; González, María E; Carrasco, Pedro

    2011-01-01

    Polyamines have been globally associated to plant responses to abiotic stress. Particularly, putrescine has been related to a better response to cold and dehydration stresses. It is known that this polyamine is involved in cold tolerance, since Arabidopsis thaliana plants mutated in the key enzyme responsible for putrescine synthesis (arginine decarboxilase, ADC; EC 4.1.1.19) are more sensitive than the wild type to this stress. Although it is speculated that the overexpression of ADC genes may confer tolerance, this is hampered by pleiotropic effects arising from the constitutive expression of enzymes from the polyamine metabolism. Here, we present our work using A. thaliana transgenic plants harboring the ADC gene from oat under the control of a stress-inducible promoter (pRD29A) instead of a constitutive promoter. The transgenic lines presented in this work were more resistant to both cold and dehydration stresses, associated with a concomitant increment in endogenous putrescine levels under stress. Furthermore, the increment in putrescine upon cold treatment correlates with the induction of known stress-responsive genes, and suggests that putrescine may be directly or indirectly involved in ABA metabolism and gene expression. PMID:21330789

  2. Putrescine accumulation in Arabidopsis thaliana transgenic lines enhances tolerance to dehydration and freezing stress.

    PubMed

    Alet, Analía I; Sanchez, Diego H; Cuevas, Juan C; Del Valle, Secundino; Altabella, Teresa; Tiburcio, Antonio F; Marco, Francisco; Ferrando, Alejandro; Espasandín, Fabiana D; González, María E; Ruiz, Oscar A; Carrasco, Pedro

    2011-02-01

    Polyamines have been globally associated to plant responses to abiotic stress. Particularly, putrescine has been related to a better response to cold and dehydration stresses. It is known that this polyamine is involved in cold tolerance, since Arabidopsis thaliana plants mutated in the key enzyme responsible for putrescine synthesis (arginine decarboxilase, ADC; EC 4.1.1.19) are more sensitive than the wild type to this stress. Although it is speculated that the over-expression of ADC genes may confer tolerance, this is hampered by pleiotropic effects arising from the constitutive expression of enzymes from the polyamine metabolism. Here, we present our work using A. thaliana transgenic plants harboring the ADC gene from oat under the control of a stress-inducible promoter (pRD29A) instead of a constitutive promoter. The transgenic lines presented in this work were more resistant to both cold and dehydration stresses, associated with a concomitant increment in endogenous putrescine levels under stress. Furthermore, the increment in putrescine upon cold treatment correlated with the induction of known stress-responsive genes, and suggested that putrescine may be directly or indirectly involved in ABA metabolism and gene expression.

  3. LMI1-like genes involved in leaf margin development of Brassica napus.

    PubMed

    Ni, Xiyuan; Liu, Han; Huang, Jixiang; Zhao, Jianyi

    2017-06-01

    In rapeseed (Brassica napus L.), leaf margins are variable and can be entire, serrate, or lobed. In our previous study, the lobed-leaf gene (LOBED-LEAF 1, BnLL1) was mapped to a 32.1 kb section of B. napus A10. Two LMI1-like genes, BnaA10g26320D and BnaA10g26330D, were considered the potential genes that controlled the lobed-leaf trait in rapeseed. In the present study, these two genes and another homologous gene (BnaC04g00850D) were transformed into Arabidopsis thaliana (L.) Heynh. plants to identify their functions. All three LMI1-like genes of B. napus produced serrate leaf margins. The expression analysis indicated that the expression level of BnaA10g26320D determined the difference between lobed- and entire-leaved lines in rapeseed. Therefore, it is likely that BnaA10g26320D corresponds to BnLL1.

  4. Genetic Dissection of Leaf Development in Brassica rapa Using a Genetical Genomics Approach1[W

    PubMed Central

    Xiao, Dong; Wang, Huange; Basnet, Ram Kumar; Zhao, Jianjun; Lin, Ke; Hou, Xilin; Bonnema, Guusje

    2014-01-01

    The paleohexaploid crop Brassica rapa harbors an enormous reservoir of morphological variation, encompassing leafy vegetables, vegetable and fodder turnips (Brassica rapa, ssp. campestris), and oil crops, with different crops having very different leaf morphologies. In the triplicated B. rapa genome, many genes have multiple paralogs that may be regulated differentially and contribute to phenotypic variation. Using a genetical genomics approach, phenotypic data from a segregating doubled haploid population derived from a cross between cultivar Yellow sarson (oil type) and cultivar Pak choi (vegetable type) were used to identify loci controlling leaf development. Twenty-five colocalized phenotypic quantitative trait loci (QTLs) contributing to natural variation for leaf morphological traits, leaf number, plant architecture, and flowering time were identified. Genetic analysis showed that four colocalized phenotypic QTLs colocalized with flowering time and leaf trait candidate genes, with their cis-expression QTLs and cis- or trans-expression QTLs for homologs of genes playing a role in leaf development in Arabidopsis (Arabidopsis thaliana). The leaf gene BRASSICA RAPA KIP-RELATED PROTEIN2_A03 colocalized with QTLs for leaf shape and plant height; BRASSICA RAPA ERECTA_A09 colocalized with QTLs for leaf color and leaf shape; BRASSICA RAPA LONGIFOLIA1_A10 colocalized with QTLs for leaf size, leaf color, plant branching, and flowering time; while the major flowering time gene, BRASSICA RAPA FLOWERING LOCUS C_A02, colocalized with QTLs explaining variation in flowering time, plant architectural traits, and leaf size. Colocalization of these QTLs points to pleiotropic regulation of leaf development and plant architectural traits in B. rapa. PMID:24394778

  5. 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

  6. Parabolic flight induces changes in gene expression patterns in Arabidopsis thaliana.

    PubMed

    Paul, Anna-Lisa; Manak, Michael S; Mayfield, John D; Reyes, Matthew F; Gurley, William B; Ferl, Robert J

    2011-10-01

    Our primary objective was to evaluate gene expression changes in Arabidopsis thaliana in response to parabolic flight as part of a comprehensive approach to the molecular biology of spaceflight-related adaptations. In addition, we wished to establish parabolic flight as a tractable operations platform for molecular biology studies. In a succession of experiments on NASA's KC-135 and C-9 parabolic aircraft, Arabidopsis plants were presented with replicated exposure to parabolic flight. Transcriptome profiling revealed that parabolic flight caused changes in gene expression patterns that stood the statistical tests of replication on three different flight days. The earliest response, after 20 parabolas, was characterized by a prominence of genes associated with signal transduction. After 40 parabolas, this prominence was largely replaced by genes associated with biotic and abiotic stimuli and stress. Among these responses, three metabolic processes stand out in particular: the induction of auxin metabolism and signaling, the differential expression of genes associated with calcium-mediated signaling, and the repression of genes associated with disease resistance and cell wall biochemistry. Many, but not all, of these responses are known to be involved in gravity sensing in plants. Changes in auxin-related gene expression were also recorded by reporter genes tuned to auxin signal pathways. These data demonstrate that the parabolic flight environment is appropriate for molecular biology research involving the transition to microgravity, in that with replication, proper controls, and analyses, gene expression changes can be observed in the time frames of typical parabolic flight experiments.

  7. The Zinc-Finger Thylakoid-Membrane Protein FIP Is Involved With Abiotic Stress Response in Arabidopsis thaliana.

    PubMed

    Lopes, Karina L; Rodrigues, Ricardo A O; Silva, Marcos C; Braga, Wiliane G S; Silva-Filho, Marcio C

    2018-01-01

    Many plant genes have their expression modulated by stress conditions. Here, we used Arabidopsis FtsH5 protease, which expression is regulated by light stress, as bait in a yeast two-hybrid screen to search for new proteins involved in the stress response. As a result, we found FIP (FtsH5 Interacting Protein), which possesses an amino proximal cleavable transit peptide, a hydrophobic membrane-anchoring region, and a carboxyl proximal C 4 -type zinc-finger domain. In vivo experiments using FIP fused to green fluorescent protein (GFP) showed a plastid localization. This finding was corroborated by chloroplast import assays that showed FIP inserted in the thylakoid membrane. FIP expression was down-regulated in plants exposed to high light intensity, oxidative, salt, and osmotic stresses, whereas mutant plants expressing low levels of FIP were more tolerant to these abiotic stresses. Our data shows a new thylakoid-membrane protein involved with abiotic stress response in Arabidopsis thaliana .

  8. The Arabidopsis Mitochondrial Protease FtSH4 Is Involved in Leaf Senescence via Regulation of WRKY-Dependent Salicylic Acid Accumulation and Signaling.

    PubMed

    Zhang, Shengchun; Li, Cui; Wang, Rui; Chen, Yaxue; Shu, Si; Huang, Ruihua; Zhang, Daowei; Li, Jian; Xiao, Shi; Yao, Nan; Yang, Chengwei

    2017-04-01

    Mitochondria and autophagy play important roles in the networks that regulate plant leaf senescence and cell death. However, the molecular mechanisms underlying the interactions between mitochondrial signaling and autophagy are currently not well understood. This study characterized the function of the Arabidopsis ( Arabidopsis thaliana ) mitochondrial AAA-protease gene FtSH4 in regulating autophagy and senescence, finding that FtSH4 mediates WRKY-dependent salicylic acid (SA) accumulation and signaling. Knockout of FtSH4 in the ftsh4-4 mutant resulted in severe leaf senescence, cell death, and high autophagy levels. The level of SA increased dramatically in the ftsh4-4 mutant. Expression of nahG in the ftsh4-4 mutant led to decreased SA levels and suppressed the leaf senescence and cell death phenotypes. The transcript levels of several SA synthesis and signaling genes, including SALICYLIC ACID INDUCTION DEFICIENT2 ( SID2 ), NON-RACE-SPECIFIC DISEASE RESISTANCE1 ( NDR1 ), and NONEXPRESSOR OF PATHOGENESIS-RELATED PROTEINS1 ( NPR1 ), increased significantly in the ftsh4-4 mutants compared with the wild type. Loss of function of SID2 , NDR1 , or NPR1 in the ftsh4-4 mutant reversed the ftsh4-4 senescence and autophagy phenotypes. Furthermore, ftsh4-4 mutants had elevated levels of transcripts of several WRKY genes, including WRKY40 , WRKY46 , WRKY51 , WRKY60 , WRKY63 , and WRKY75 ; all of these WRKY proteins can bind to the promoter of SID2 Loss of function of WRKY75 in the ftsh4-4 mutants decreased the levels of SA and reversed the senescence phenotype. Taken together, these results suggest that the mitochondrial ATP-dependent protease FtSH4 may regulate the expression of WRKY genes by modifying the level of reactive oxygen species and the WRKY transcription factors that control SA synthesis and signaling in autophagy and senescence. © 2017 American Society of Plant Biologists. All Rights Reserved.

  9. Role of carotenoids in first positive phototropism of etiolated Arabidopsis thaliana seedlings

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

    Orbovic, V.; Poff, K.L.

    1991-05-01

    A mutant of Arabidopsis thaliana, chosen for is pale cotyledon phenotype in dark grown material, has been obtained from Klaus Apel (ETH-Zentrum, Zurich, Switzerland). Fluence response curves for this putative carotenoidless mutant and its wild-type parent have been measured. The shape of the fluence response curve for the pale mutant is similar to that of its wild-type parent. However, the amplitude of curvature by the mutant is considerably lower than curvature of the wild-type. If the amplitude of the curvature is enhanced with a red light pre-irradiation, peaks of the two photoreceptor pigments, P{sub I} and P{sub II} can bemore » seen in both the pale mutant and its wild-type parent. Based on these data, the authors conclude that neither photoreceptor pigment is altered in the pale mutant.« less

  10. Lunisolar tidal force and its relationship to chlorophyll fluorescence in Arabidopsis thaliana.

    PubMed

    Fisahn, Joachim; Klingelé, Emile; Barlow, Peter

    2015-01-01

    The yield of chlorophyll fluorescence Ft was measured in leaves of Arabidopsis thaliana over periods of several days under conditions of continuous illumination (LL) without the application of saturating light pulses. After linearization of the time series of the chlorophyll fluorescence yield (ΔFt), oscillations became apparent with periodicities in the circatidal range. Alignments of these linearized time series ΔFt with the lunisolar tidal acceleration revealed high degrees of synchrony and phase congruence. Similar congruence with the lunisolar tide was obtained with the linearized quantum yield of PSII (ΔФII), recorded after application of saturating light pulses. These findings strongly suggest that there is an exogenous timekeeper which is a stimulus for the oscillations detected in both the linearized yield of chlorophyll fluorescence (ΔFt) and the linearized quantum yield of PSII (ΔФII).

  11. Lunisolar tidal force and its relationship to chlorophyll fluorescence in Arabidopsis thaliana

    PubMed Central

    Fisahn, Joachim; Klingelé, Emile; Barlow, Peter

    2015-01-01

    The yield of chlorophyll fluorescence Ft was measured in leaves of Arabidopsis thaliana over periods of several days under conditions of continuous illumination (LL) without the application of saturating light pulses. After linearization of the time series of the chlorophyll fluorescence yield (ΔFt), oscillations became apparent with periodicities in the circatidal range. Alignments of these linearized time series ΔFt with the lunisolar tidal acceleration revealed high degrees of synchrony and phase congruence. Similar congruence with the lunisolar tide was obtained with the linearized quantum yield of PSII (ΔФII), recorded after application of saturating light pulses. These findings strongly suggest that there is an exogenous timekeeper which is a stimulus for the oscillations detected in both the linearized yield of chlorophyll fluorescence (ΔFt) and the linearized quantum yield of PSII (ΔФII). PMID:26376108

  12. Cloning and characterization of the gene encoding IMP dehydrogenase from Arabidopsis thaliana.

    PubMed

    Collart, F R; Osipiuk, J; Trent, J; Olsen, G J; Huberman, E

    1996-10-03

    We have cloned and characterized the gene encoding inosine monophosphate dehydrogenase (IMPDH) from Arabidopsis thaliana (At). The transcription unit of the At gene spans approximately 1900 bp and specifies a protein of 503 amino acids with a calculated relative molecular mass (M(r)) of 54,190. The gene is comprised of a minimum of four introns and five exons with all donor and acceptor splice sequences conforming to previously proposed consensus sequences. The deduced IMPDH amino-acid sequence from At shows a remarkable similarity to other eukaryotic IMPDH sequences, with a 48% identity to human Type II enzyme. Allowing for conservative substitutions, the enzyme is 69% similar to human Type II IMPDH. The putative active-site sequence of At IMPDH conforms to the IMP dehydrogenase/guanosine monophosphate reductase motif and contains an essential active-site cysteine residue.

  13. Distinct physiological and molecular responses in Arabidopsis thaliana exposed to aluminum oxide nanoparticles and ionic aluminum.

    PubMed

    Jin, Yujian; Fan, Xiaoji; Li, Xingxing; Zhang, Zhenyan; Sun, Liwei; Fu, Zhengwei; Lavoie, Michel; Pan, Xiangliang; Qian, Haifeng

    2017-09-01

    Nano-aluminium oxide (nAl 2 O 3 ) is one of the most widely used nanomaterials. However, nAl 2 O 3 toxicity mechanisms and potential beneficial effects on terrestrial plant physiology remain poorly understood. Such knowledge is essential for the development of robust nAl 2 O 3 risk assessment. In this study, we studied the influence of a 10-d exposure to a total selected concentration of 98 μM nAl 2 O 3 or to the equivalent molar concentration of ionic Al (AlCl 3 ) (196 μM) on the model plant Arabidopsis thaliana on the physiology (e.g., growth and photosynthesis, membrane damage) and the transcriptome using a high throughput state-of-the-art technology, RNA-seq. We found no evidence of nAl 2 O 3 toxicity on photosynthesis, growth and lipid peroxidation. Rather the nAl 2 O 3 treatment stimulated root weight and length by 48% and 39%, respectively as well as photosynthesis opening up the door to the use of nAl 2 O 3 in biotechnology and nano agriculture. Transcriptomic analyses indicate that the beneficial effect of nAl 2 O 3 was related to an increase in the transcription of several genes involved in root growth as well as in root nutrient uptake (e.g., up-regulation of the root hair-specific gene family and root development genes, POLARIS protein). By contrast, the ionic Al treatment decreased shoot and root weight of Arabidopsis thaliana by 57.01% and 45.15%, respectively. This toxic effect was coupled to a range of response at the gene transcription level including increase transcription of antioxidant-related genes and transcription of genes involved in plant defense response to pathogens. This work provides an integrated understanding at the molecular and physiological level of the effects of nAl 2 O 3 and ionic Al in Arabidopsis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Quantitative proteomics reveals the importance of nitrogen source to control glucosinolate metabolism in Arabidopsis thaliana and Brassica oleracea

    PubMed Central

    Marino, Daniel; Ariz, Idoia; Lasa, Berta; Santamaría, Enrique; Fernández-Irigoyen, Joaquín; González-Murua, Carmen; Aparicio Tejo, Pedro M.

    2016-01-01

    Accessing different nitrogen (N) sources involves a profound adaptation of plant metabolism. In this study, a quantitative proteomic approach was used to further understand how the model plant Arabidopsis thaliana adjusts to different N sources when grown exclusively under nitrate or ammonium nutrition. Proteome data evidenced that glucosinolate metabolism was differentially regulated by the N source and that both TGG1 and TGG2 myrosinases were more abundant under ammonium nutrition, which is generally considered to be a stressful situation. Moreover, Arabidopsis plants displayed glucosinolate accumulation and induced myrosinase activity under ammonium nutrition. Interestingly, these results were also confirmed in the economically important crop broccoli (Brassica oleracea var. italica). Moreover, these metabolic changes were correlated in Arabidopsis with the differential expression of genes from the aliphatic glucosinolate metabolic pathway. This study underlines the importance of nitrogen nutrition and the potential of using ammonium as the N source in order to stimulate glucosinolate metabolism, which may have important applications not only in terms of reducing pesticide use, but also for increasing plants’ nutritional value. PMID:27085186

  15. Evaluation of glyphosate resistance in Arabidopsis thaliana expressing an altered target site EPSPS

    PubMed Central

    You, Jinsong; Qi, Youlin; Flasinski, Stanislaw; Kavanaugh, Christina; Washam, Jeannie; Ostrander, Elizabeth; Wang, Dafu; Heck, Greg

    2017-01-01

    Abstract BACKGROUND Glyphosate‐resistant goosegrass has recently evolved and is homozygous for the double mutant of EPSPS (T102I, P106S or TIPS). These same mutations combined with EPSPS overexpression, have been used to create transgenic glyphosate‐resistant crops. Arabidopsis thaliana (Wt EPSPS K i ∼ 0.5 μM) was engineered to express a variant AtEPSPS‐T102I, P106A (TIPA K i = 150 μM) to determine the resistance magnitude for a more potent variant EPSPS that might evolve in weeds. RESULTS Transgenic A. thaliana plants, homozygous for one, two or four copies of AtEPSPS‐TIPA, had resistance (IC50 values, R/S) as measured by seed production ranging from 4.3‐ to 16‐fold. Plants treated in reproductive stage were male sterile with a range of R/S from 10.1‐ to 40.6‐fold. A significant hormesis (∼ 63% gain in fresh weight) was observed for all genotypes when treated at the initiation of reproductive stage with 0.013 kg ha–1. AtEPSPS‐TIPA enzyme activity was proportional to copy number and correlated with resistance magnitude. CONCLUSIONS A. thaliana, as a model weed expressing one copy of AtEPSPS‐TIPA (300‐fold more resistant), had only 4.3‐fold resistance to glyphosate for seed production. Resistance behaved as a single dominant allele. Vegetative tissue resistance was 4.7‐fold greater than reproductive tissue resistance and was linear with gene copy number. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:28677849

  16. Phenolics from Ageratina adenophora roots and their phytotoxic effects on Arabidopsis thaliana seed germination and seedling growth.

    PubMed

    Zhou, Zhong-Yu; Liu, Wan-Xue; Pei, Gang; Ren, Hui; Wang, Jing; Xu, Qiao-Lin; Xie, Hai-Hui; Wan, Fang-Hao; Tan, Jian-Wen

    2013-12-04

    A bioassay-directed phytochemical study was conducted to investigate potential allelochemicals in the roots of the invasive plant Ageratina adenophora. Eleven phenolic compounds, including seven new ones, 7-hydroxy-8,9-dehydrothymol 9-O-trans-ferulate (1), 7-hydroxythymol 9-O-trans-ferulate (2), 7,8-dihydroxythymol 9-O-trans-ferulate (3), 7,8-dihydroxythymol 9-O-cis-ferulate (4), methyl (7R)-3-deoxy-4,5-epoxy-D-manno-2-octulosonate 8-O-trans-p-coumarate (5), methyl (7R)-3-deoxy-4,5-epoxy-D-manno-2-octulosonate 8-O-cis-p-coumarate (6), and 3-(2-hydroxyphenyl)propyl methyl malonate (7), were isolated from a bioactive subfraction of the ethanol extract of the roots of A. adenophora. The new structures were established on the basis of detailed spectroscopic analysis. The potential phytotoxic effects of these compounds on the germination of Arabidopsis thaliana seeds were tested by a filter paper assay. Compound 7 and known compounds 3-(2-hydroxyphenyl)-1-propanol (8) and o-coumaric acid (9) remarkably showed inhibition activity against Arabidopsis seed germination at a concentration of 1.0 mM. Compounds 1, 2, 5, 6, and 10 showed slight inhibitory activity at the test concentration after treatment for 3 days, while the other compounds showed no obvious inhibitory effects. Moreover, 7-9 were further found to show obvious inhibitory activity on retarding the seedling growth of Ar. thaliana cultured in soil medium.

  17. Unraveling the function of Arabidopsis thaliana OS9 in the endoplasmic reticulum-associated degradation of glycoproteins.

    PubMed

    Hüttner, Silvia; Veit, Christiane; Schoberer, Jennifer; Grass, Josephine; Strasser, Richard

    2012-05-01

    In the endoplasmic reticulum, immature polypeptides coincide with terminally misfolded proteins. Consequently, cells need a well-balanced quality control system, which decides about the fate of individual proteins and maintains protein homeostasis. Misfolded and unassembled proteins are sent for destruction via the endoplasmic reticulum-associated degradation (ERAD) machinery to prevent the accumulation of potentially toxic protein aggregates. Here, we report the identification of Arabidopsis thaliana OS9 as a component of the plant ERAD pathway. OS9 is an ER-resident glycoprotein containing a mannose-6-phosphate receptor homology domain, which is also found in yeast and mammalian lectins involved in ERAD. OS9 fused to the C-terminal domain of YOS9 can complement the ERAD defect of the corresponding yeast Δyos9 mutant. An A. thaliana OS9 loss-of-function line suppresses the severe growth phenotype of the bri1-5 and bri1-9 mutant plants, which harbour mutated forms of the brassinosteroid receptor BRI1. Co-immunoprecipitation studies demonstrated that OS9 associates with Arabidopsis SEL1L/HRD3, which is part of the plant ERAD complex and with the ERAD substrates BRI1-5 and BRI1-9, but only the binding to BRI1-5 occurs in a glycan-dependent way. OS9-deficiency results in activation of the unfolded protein response and reduces salt tolerance, highlighting the role of OS9 during ER stress. We propose that OS9 is a component of the plant ERAD machinery and may act specifically in the glycoprotein degradation pathway.

  18. Neighbor detection at the leaf tip adaptively regulates upward leaf movement through spatial auxin dynamics

    PubMed Central

    Reinen, Emilie; Anten, Niels P. R.

    2017-01-01

    Vegetation stands have a heterogeneous distribution of light quality, including the red/far-red light ratio (R/FR) that informs plants about proximity of neighbors. Adequate responses to changes in R/FR are important for competitive success. How the detection and response to R/FR are spatially linked and how this spatial coordination between detection and response affects plant performance remains unresolved. We show in Arabidopsis thaliana and Brassica nigra that localized FR enrichment at the lamina tip induces upward leaf movement (hyponasty) from the petiole base. Using a combination of organ-level transcriptome analysis, molecular reporters, and physiology, we show that PIF-dependent spatial auxin dynamics are key to this remote response to localized FR enrichment. Using computational 3D modeling, we show that remote signaling of R/FR for hyponasty has an adaptive advantage over local signaling in the petiole, because it optimizes the timing of leaf movement in response to neighbors and prevents hyponasty caused by self-shading. PMID:28652357

  19. Stomatal and pavement cell density linked to leaf internal CO2 concentration

    PubMed Central

    Šantrůček, Jiří; Vráblová, Martina; Šimková, Marie; Hronková, Marie; Drtinová, Martina; Květoň, Jiří; Vrábl, Daniel; Kubásek, Jiří; Macková, Jana; Wiesnerová, Dana; Neuwithová, Jitka; Schreiber, Lukas

    2014-01-01

    Background and Aims Stomatal density (SD) generally decreases with rising atmospheric CO2 concentration, Ca. However, SD is also affected by light, air humidity and drought, all under systemic signalling from older leaves. This makes our understanding of how Ca controls SD incomplete. This study tested the hypotheses that SD is affected by the internal CO2 concentration of the leaf, Ci, rather than Ca, and that cotyledons, as the first plant assimilation organs, lack the systemic signal. Methods Sunflower (Helianthus annuus), beech (Fagus sylvatica), arabidopsis (Arabidopsis thaliana) and garden cress (Lepidium sativum) were grown under contrasting environmental conditions that affected Ci while Ca was kept constant. The SD, pavement cell density (PCD) and stomatal index (SI) responses to Ci in cotyledons and the first leaves of garden cress were compared. 13C abundance (δ13C) in leaf dry matter was used to estimate the effective Ci during leaf development. The SD was estimated from leaf imprints. Key Results SD correlated negatively with Ci in leaves of all four species and under three different treatments (irradiance, abscisic acid and osmotic stress). PCD in arabidopsis and garden cress responded similarly, so that SI was largely unaffected. However, SD and PCD of cotyledons were insensitive to Ci, indicating an essential role for systemic signalling. Conclusions It is proposed that Ci or a Ci-linked factor plays an important role in modulating SD and PCD during epidermis development and leaf expansion. The absence of a Ci–SD relationship in the cotyledons of garden cress indicates the key role of lower-insertion CO2 assimilation organs in signal perception and its long-distance transport. PMID:24825295

  20. CB5C affects the glucosinolate profile in Arabidopsis thaliana

    PubMed Central

    Vik, Daniel; Crocoll, Christoph; Andersen, Tonni Grube; Burow, Meike; Halkier, Barbara Ann

    2016-01-01

    ABSTRACT Cytochrome b5 (CB5) proteins are small heme-binding proteins, that influence cytochrome P450 activity. While only one CB5 isoform is found in mammals, higher plants have several isoforms of these proteins. The roles of the many CB5 isoforms in plants remain unknown. We hypothesized that CB5 proteins support the cytochrome P450 enzymes of plant specialized metabolism and found CB5C from Arabidopsis thaliana to co-express with glucosinolate biosynthetic genes. We characterized the glucosinolate profiles of 2 T-DNA insertion mutants of CB5C, and found that long-chained aliphatic glucosinolates were reduced in one of the mutant lines – a phenotype that was exaggerated upon methyl-jasmonate treatment. These results support the hypothesis, that CB5C influences glucosinolate biosynthesis, however, the mode of action remains unknown. Furthermore, the mutants differed in their biomass response to methyl jasmonate treatment. Thereby, our results highlight the varying effects of T-DNA insertion sites, as the 2 analyzed alleles show different phenotypes. PMID:27454255

  1. Dissecting Arabidopsis Gβ Signal Transduction on the Protein Surface1[W][OA

    PubMed Central

    Jiang, Kun; Frick-Cheng, Arwen; Trusov, Yuri; Delgado-Cerezo, Magdalena; Rosenthal, David M.; Lorek, Justine; Panstruga, Ralph; Booker, Fitzgerald L.; Botella, José Ramón; Molina, Antonio; Ort, Donald R.; Jones, Alan M.

    2012-01-01

    The heterotrimeric G-protein complex provides signal amplification and target specificity. The Arabidopsis (Arabidopsis thaliana) Gβ-subunit of this complex (AGB1) interacts with and modulates the activity of target cytoplasmic proteins. This specificity resides in the structure of the interface between AGB1 and its targets. Important surface residues of AGB1, which were deduced from a comparative evolutionary approach, were mutated to dissect AGB1-dependent physiological functions. Analysis of the capacity of these mutants to complement well-established phenotypes of Gβ-null mutants revealed AGB1 residues critical for specific AGB1-mediated biological processes, including growth architecture, pathogen resistance, stomata-mediated leaf-air gas exchange, and possibly photosynthesis. These findings provide promising new avenues to direct the finely tuned engineering of crop yield and traits. PMID:22570469

  2. Mutants of Arabidopsis thaliana with decreased amplitude in their phototropic response

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

    Khurana, J.P.; Ren, Zhangling; Steinitz, B.

    1989-10-01

    Two mutants of Arabidopsis thaliana have been identified with decreased phototropism to 450-nanometer light. Fluence-response relationships for these strains (ZR8 and ZR19) to single and multiple flashes of light show thresholds, curve shapes, and fluence for maximum curvature in first positive phototropism which are the same as those of the wild type. Similarly, there is no alteration from the wild type in the kinetics of curvature or in the optimum dark period separating sequential flashes in a multiple flash regimen. In addition, in both strains, gravitropism is decreased compared to the wild type by an amount which is comparable tomore » the decrease in phototropism. Based on reciprocal backcrosses, it appears that the alteration is due to a recessive nuclear mutation. It is suggested that ZR8 and ZR19 represent alterations in some step analogous to an amplifier, downstream of the photoreceptor pigment, and common to both phototropism and gravitropism.« less

  3. Mutants of Arabidopsis thaliana with decreased amplitude in their phototropic response

    NASA Technical Reports Server (NTRS)

    Khurana, J. P.; Ren, Z.; Steinitz, B.; Parks, B.; Best, T. R.; Poff, K. L.

    1989-01-01

    Two mutants of Arabidopsis thaliana have been identified with decreased phototropism to 450-nanometer light. Fluence-response relationships for these strains (ZR8 and ZR19) to single and multiple flashes of light show thresholds, curve shapes, and fluence for maximum curvature in first positive' phototropism which are the same as those of the wild type. Similarly, there is no alteration from the wild type in the kinetics of curvature or in the optimum dark period separating sequential flashes in a multiple flash regimen. In addition, in both strains, gravitropism is decreased compared to the wild type by an amount which is comparable to the decrease in phototropism. Based on reciprocal backcrosses, it appears that the alteration is due to a recessive nuclear mutation. It is suggested that ZR8 and ZR19 represent alterations in some step analogous to an amplifier, downstream of the photoreceptor pigment, and common to both phototropism and gravitropism.

  4. Dynamic F-actin movement is essential for fertilization in Arabidopsis thaliana

    PubMed Central

    Kawashima, Tomokazu; Maruyama, Daisuke; Shagirov, Murat; Li, Jing; Hamamura, Yuki; Yelagandula, Ramesh; Toyama, Yusuke; Berger, Frédéric

    2014-01-01

    In animals, microtubules and centrosomes direct the migration of gamete pronuclei for fertilization. By contrast, flowering plants have lost essential components of the centrosome, raising the question of how flowering plants control gamete nuclei migration during fertilization. Here, we use Arabidopsis thaliana to document a novel mechanism that regulates F-actin dynamics in the female gametes and is essential for fertilization. Live imaging shows that F-actin structures assist the male nucleus during its migration towards the female nucleus. We identify a female gamete-specific Rho-GTPase that regulates F-actin dynamics and further show that actin–myosin interactions are also involved in male gamete nucleus migration. Genetic analyses and imaging indicate that microtubules are dispensable for migration and fusion of male and female gamete nuclei. The innovation of a novel actin-based mechanism of fertilization during plant evolution might account for the complete loss of the centrosome in flowering plants. DOI: http://dx.doi.org/10.7554/eLife.04501.001 PMID:25303363

  5. The Arabidopsis thaliana mobilome and its impact at the species level

    PubMed Central

    Quadrana, Leandro; Bortolini Silveira, Amanda; Mayhew, George F; LeBlanc, Chantal; Martienssen, Robert A; Jeddeloh, Jeffrey A; Colot, Vincent

    2016-01-01

    Transposable elements (TEs) are powerful motors of genome evolution yet a comprehensive assessment of recent transposition activity at the species level is lacking for most organisms. Here, using genome sequencing data for 211 Arabidopsis thaliana accessions taken from across the globe, we identify thousands of recent transposition events involving half of the 326 TE families annotated in this plant species. We further show that the composition and activity of the 'mobilome' vary extensively between accessions in relation to climate and genetic factors. Moreover, TEs insert equally throughout the genome and are rapidly purged by natural selection from gene-rich regions because they frequently affect genes, in multiple ways. Remarkably, loci controlling adaptive responses to the environment are the most frequent transposition targets observed. These findings demonstrate the pervasive, species-wide impact that a rich mobilome can have and the importance of transposition as a recurrent generator of large-effect alleles. DOI: http://dx.doi.org/10.7554/eLife.15716.001 PMID:27258693

  6. Combining classifiers to predict gene function in Arabidopsis thaliana using large-scale gene expression measurements.

    PubMed

    Lan, Hui; Carson, Rachel; Provart, Nicholas J; Bonner, Anthony J

    2007-09-21

    Arabidopsis thaliana is the model species of current plant genomic research with a genome size of 125 Mb and approximately 28,000 genes. The function of half of these genes is currently unknown. The purpose of this study is to infer gene function in Arabidopsis using machine-learning algorithms applied to large-scale gene expression data sets, with the goal of identifying genes that are potentially involved in plant response to abiotic stress. Using in house and publicly available data, we assembled a large set of gene expression measurements for A. thaliana. Using those genes of known function, we first evaluated and compared the ability of basic machine-learning algorithms to predict which genes respond to stress. Predictive accuracy was measured using ROC50 and precision curves derived through cross validation. To improve accuracy, we developed a method for combining these classifiers using a weighted-voting scheme. The combined classifier was then trained on genes of known function and applied to genes of unknown function, identifying genes that potentially respond to stress. Visual evidence corroborating the predictions was obtained using electronic Northern analysis. Three of the predicted genes were chosen for biological validation. Gene knockout experiments confirmed that all three are involved in a variety of stress responses. The biological analysis of one of these genes (At1g16850) is presented here, where it is shown to be necessary for the normal response to temperature and NaCl. Supervised learning methods applied to large-scale gene expression measurements can be used to predict gene function. However, the ability of basic learning methods to predict stress response varies widely and depends heavily on how much dimensionality reduction is used. Our method of combining classifiers can improve the accuracy of such predictions - in this case, predictions of genes involved in stress response in plants - and it effectively chooses the appropriate amount

  7. N-Acylethanolamine metabolism interacts with abscisic acid signaling in Arabidopsis thaliana seedlings.

    PubMed

    Teaster, Neal D; Motes, Christy M; Tang, Yuhong; Wiant, William C; Cotter, Matthew Q; Wang, Yuh-Shuh; Kilaru, Aruna; Venables, Barney J; Hasenstein, Karl H; Gonzalez, Gabriel; Blancaflor, Elison B; Chapman, Kent D

    2007-08-01

    N-Acylethanolamines (NAEs) are bioactive acylamides that are present in a wide range of organisms. In plants, NAEs are generally elevated in desiccated seeds, suggesting that they may play a role in seed physiology. NAE and abscisic acid (ABA) levels were depleted during seed germination, and both metabolites inhibited the growth of Arabidopsis thaliana seedlings within a similar developmental window. Combined application of low levels of ABA and NAE produced a more dramatic reduction in germination and growth than either compound alone. Transcript profiling and gene expression studies in NAE-treated seedlings revealed elevated transcripts for a number of ABA-responsive genes and genes typically enriched in desiccated seeds. The levels of ABI3 transcripts were inversely associated with NAE-modulated growth. Overexpression of the Arabidopsis NAE degrading enzyme fatty acid amide hydrolase resulted in seedlings that were hypersensitive to ABA, whereas the ABA-insensitive mutants, abi1-1, abi2-1, and abi3-1, exhibited reduced sensitivity to NAE. Collectively, our data indicate that an intact ABA signaling pathway is required for NAE action and that NAE may intersect the ABA pathway downstream from ABA. We propose that NAE metabolism interacts with ABA in the negative regulation of seedling development and that normal seedling establishment depends on the reduction of the endogenous levels of both metabolites.

  8. Multi site polyadenylation and transcriptional response to stress of a vacuolar type H+-ATPase subunit A gene in Arabidopsis thaliana

    PubMed Central

    Magnotta, Scot M; Gogarten, Johann Peter

    2002-01-01

    Background Vacuolar type H+-ATPases play a critical role in the maintenance of vacuolar homeostasis in plant cells. V-ATPases are also involved in plants' defense against environmental stress. This research examined the expression and regulation of the catalytic subunit of the vacuolar type H+-ATPase in Arabidopsis thaliana and the effect of environmental stress on multiple transcripts generated by this gene. Results Evidence suggests that subunit A of the vacuolar type H+-ATPase is encoded by a single gene in Arabidopsis thaliana. Genome blot analysis showed no indication of a second subunit A gene being present. The single gene identified was shown by whole RNA blot analysis to be transcribed in all organs of the plant. Subunit A was shown by sequencing the 3' end of multiple cDNA clones to exhibit multi site polyadenylation. Four different poly (A) tail attachment sites were revealed. Experiments were performed to determine the response of transcript levels for subunit A to environmental stress. A PCR based strategy was devised to amplify the four different transcripts from the subunit A gene. Conclusions Amplification of cDNA generated from seedlings exposed to cold, salt stress, and etiolation showed that transcript levels for subunit A of the vacuolar type H+-ATPase in Arabidopsis were responsive to stress conditions. Cold and salt stress resulted in a 2–4 fold increase in all four subunit A transcripts evaluated. Etiolation resulted in a slight increase in transcript levels. All four transcripts appeared to behave identically with respect to stress conditions tested with no significant differential regulation. PMID:11985780

  9. Identification and characterization of the SSB1 locus involved in symptom development by Spring beauty latent virus infection in Arabidopsis thaliana.

    PubMed

    Fujisaki, Koki; Hagihara, Fumi; Azukawa, Yoshihiro; Kaido, Masanori; Okuno, Tetsuro; Mise, Kazuyuki

    2004-09-01

    The natural variation of Arabidopsis thaliana in response to a bromovirus, Spring beauty latent virus (SBLV), was examined. Of 63 Arabidopsis accessions tested, all were susceptible when inoculated with SBLV, although there was a large degree of variation in symptom development. Most accessions, including Columbia (Col-0), were symptomless or developed only mild symptoms, but four accessions, including S96, showed severe symptoms of SBLV infection. Genetic analysis suggested that the difference in the responses of Col-0 and S96 to SBLV was controlled by a single semidominant locus. We have designated this locus SSB1 (symptom development by SBLV infection). By using genetic markers, SSB1 was mapped to chromosome IV. The patterns of distribution and accumulation of SBLV in sensitive accessions were similar to those in the insensitive accessions. In addition, symptom development in S96 by SBLV infection was critically interrupted by the presence of the NahG gene, which encodes salicylic acid (SA) hydroxylase. These data suggest that symptom development in A. thaliana controlled by SSB1 is independent of the efficiency of SBLV multiplication and is dependent on SA signaling.

  10. FUM2, a Cytosolic Fumarase, Is Essential for Acclimation to Low Temperature in Arabidopsis thaliana1[OPEN

    PubMed Central

    Dyson, Beth C.; Miller, Matthew A.E.; Feil, Regina; Rattray, Nicholas; Bowsher, Caroline G.

    2016-01-01

    Although cold acclimation is a key process in plants from temperate climates, the mechanisms sensing low temperature remain obscure. Here, we show that the accumulation of the organic acid fumaric acid, mediated by the cytosolic fumarase FUM2, is essential for cold acclimation of metabolism in the cold-tolerant model species Arabidopsis (Arabidopsis thaliana). A nontargeted metabolomic approach, using gas chromatography-mass spectrometry, identifies fumarate as a key component of the cold response in this species. Plants of T-DNA insertion mutants, lacking FUM2, show marked differences in their response to cold, with contrasting responses both in terms of metabolite concentrations and gene expression. The fum2 plants accumulated higher concentrations of phosphorylated sugar intermediates and of starch and malate. Transcripts for proteins involved in photosynthesis were markedly down-regulated in fum2.2 but not in wild-type Columbia-0. Plants of fum2 show a complete loss of the ability to acclimate photosynthesis to low temperature. We conclude that fumarate accumulation plays an essential role in low temperature sensing in Arabidopsis, either indirectly modulating metabolic or redox signals or possibly being itself directly involved in cold sensing. PMID:27440755

  11. Following Vegetative to Embryonic Cellular Changes in Leaves of Arabidopsis Overexpressing LEAFY COTYLEDON21[W][OPEN

    PubMed Central

    Feeney, Mistianne; Frigerio, Lorenzo; Cui, Yuhai; Menassa, Rima

    2013-01-01

    Embryogenesis in flowering plants is controlled by a complex interplay of genetic, biochemical, and physiological regulators. LEAFY COTYLEDON2 (LEC2) is among a small number of key transcriptional regulators that are known to play important roles in controlling major events during the maturation stage of embryogenesis, notably, the synthesis and accumulation of storage reserves. LEC2 overexpression causes vegetative tissues to change their developmental fate to an embryonic state; however, little information exists about the cellular changes that take place. We show that LEC2 alters leaf morphology and anatomy and causes embryogenic structures to form subcellularly in leaves of Arabidopsis (Arabidopsis thaliana). Chloroplasts accumulate more starch, the cytoplasm fills with oil bodies, and lytic vacuoles (LVs) appear smaller in size and accumulate protein deposits. Because LEC2 is responsible for activating the synthesis of seed storage proteins (SSPs) during seed development, SSP accumulation was investigated in leaves. The major Arabidopsis SSP families were shown to accumulate within small leaf vacuoles. By exploiting the developmental and tissue-specific localization of two tonoplast intrinsic protein isoforms, the small leaf vacuoles were identified as protein storage vacuoles (PSVs). Confocal analyses of leaf vacuoles expressing fluorescently labeled tonoplast intrinsic protein isoforms reveal an altered tonoplast morphology resembling an amalgamation of a LV and PSV. Results suggest that as the LV transitions to a PSV, the tonoplast remodels before the large vacuole lumen is replaced by smaller PSVs. Finally, using vegetative and seed markers to monitor the transition, we show that LEC2 induces a reprogramming of leaf development. PMID:23780897

  12. Impaired pH homeostasis in Arabidopsis lacking the vacuolar dicarboxylate transporter and analysis of carboxylic acid transport across the tonoplast.

    PubMed

    Hurth, Marco Alois; Suh, Su Jeoung; Kretzschmar, Tobias; Geis, Tina; Bregante, Monica; Gambale, Franco; Martinoia, Enrico; Neuhaus, H Ekkehard

    2005-03-01

    Arabidopsis (Arabidopsis thaliana) mutants lacking the tonoplastic malate transporter AttDT (A. thaliana tonoplast dicarboxylate transporter) and wild-type plants showed no phenotypic differences when grown under standard conditions. To identify putative metabolic changes in AttDT knock-out plants, we provoked a metabolic scenario connected to an increased consumption of dicarboxylates. Acidification of leaf discs stimulated dicarboxylate consumption and led to extremely low levels of dicarboxylates in mutants. To investigate whether reduced dicarboxylate concentrations in mutant leaf cells and, hence, reduced capacity to produce OH(-) to overcome acidification might affect metabolism, we measured photosynthetic oxygen evolution under conditions where the cytosol is acidified. AttDT::tDNA protoplasts showed a much stronger inhibition of oxygen evolution at low pH values when compared to wild-type protoplasts. Apparently citrate, which is present in higher amounts in knock-out plants, is not able to replace dicarboxylates to overcome acidification. To raise more information on the cellular level, we performed localization studies of carboxylates. Although the total pool of carboxylates in mutant vacuoles was nearly unaltered, these organelles contained a lower proportion of malate and fumarate and a higher proportion of citrate when compared to wild-type vacuoles. These alterations concur with the observation that radioactively labeled malate and citrate are transported into Arabidopsis vacuoles by different carriers. In addition, wild-type vacuoles and corresponding organelles from AttDT::tDNA mutants exhibited similar malate channel activities. In conclusion, these results show that Arabidopsis vacuoles contain at least two transporters and a channel for dicarboxylates and citrate and that the activity of AttDT is critical for regulation of pH homeostasis.

  13. Detection of active transposable elements in Arabidopsis thaliana using Oxford Nanopore Sequencing technology.

    PubMed

    Debladis, Emilie; Llauro, Christel; Carpentier, Marie-Christine; Mirouze, Marie; Panaud, Olivier

    2017-07-17

    Transposables elements (TEs) contribute to both structural and functional dynamics of most eukaryotic genomes. Because of their propensity to densely populate plant and animal genomes, the precise estimation of the impact of transposition on genomic diversity has been considered as one of the main challenges of today's genomics. The recent development of NGS (next generation sequencing) technologies has open new perspectives in population genomics by providing new methods for high throughput detection of Transposable Elements-associated Structural Variants (TEASV). However, these have relied on Illumina platform that generates short reads (up to 350 nucleotides). This limitation in size of sequence reads can cause high false discovery rate (FDR) and therefore limit the power of detection of TEASVs, especially in the case of large, complex genomes. The newest sequencing technologies, such as Oxford Nanopore Technologies (ONT) can generate kilobases-long reads thus representing a promising tool for TEASV detection in plant and animals. We present the results of a pilot experiment for TEASV detection on the model plant species Arabidopsis thaliana using ONT sequencing and show that it can be used efficiently to detect TE movements. We generated a ~0.8X genome coverage of a met1-derived epigenetic recombinant inbred line (epiRIL) using a MinIon device with R7 chemistry. We were able to detect nine new copies of the LTR-retrotransposon Evadé (EVD). We also evidenced the activity of the DNA transposon CACTA, CAC1. Even at a low sequence coverage (0.8X), ONT sequencing allowed us to reliably detect several TE insertions in Arabidopsis thaliana genome. The long read length allowed a precise and un-ambiguous mapping of the structural variations caused by the activity of TEs. This suggests that the trade-off between read length and genome coverage for TEASV detection may be in favor of the former. Should the technology be further improved both in terms of lower error rate

  14. Geomagnetic Field (Gmf) and Plant Evolution: Investigating the Effects of Gmf Reversal on Arabidopsis thaliana Development and Gene Expression

    PubMed Central

    Bertea, Cinzia M.; Narayana, Ravishankar; Agliassa, Chiara; Rodgers, Christopher T.; Maffei, Massimo E.

    2015-01-01

    One of the most stimulating observations in plant evolution is a correlation between the occurrence of geomagnetic field (GMF) reversals (or excursions) and the moment of the radiation of Angiosperms. This led to the hypothesis that alterations in GMF polarity may play a role in plant evolution. Here, we describe a method to test this hypothesis by exposing Arabidopsis thaliana to artificially reversed GMF conditions. We used a three-axis magnetometer and the collected data were used to calculate the magnitude of the GMF. Three DC power supplies were connected to three Helmholtz coil pairs and were controlled by a computer to alter the GMF conditions. Plants grown in Petri plates were exposed to both normal and reversed GMF conditions. Sham exposure experiments were also performed. Exposed plants were photographed during the experiment and images were analyzed to calculate root length and leaf areas. Arabidopsis total RNA was extracted and Quantitative Real Time-PCR (qPCR) analyses were performed on gene expression of CRUCIFERIN 3 (CRU3), copper transport protein1 (COTP1), Redox Responsive Transcription Factor1 (RRTF1), Fe Superoxide Dismutase 1, (FSD1), Catalase3 (CAT3), Thylakoidal Ascorbate Peroxidase (TAPX), a cytosolic Ascorbate Peroxidase1 (APX1), and NADPH/respiratory burst oxidase protein D (RbohD). Four different reference genes were analysed to normalize the results of the qPCR. The best of the four genes was selected and the most stable gene for normalization was used. Our data show for the first time that reversing the GMF polarity using triaxial coils has significant effects on plant growth and gene expression. This supports the hypothesis that GMF reversal contributes to inducing changes in plant development that might justify a higher selective pressure, eventually leading to plant evolution. PMID:26649488

  15. Geomagnetic Field (Gmf) and Plant Evolution: Investigating the Effects of Gmf Reversal on Arabidopsis thaliana Development and Gene Expression.

    PubMed

    Bertea, Cinzia M; Narayana, Ravishankar; Agliassa, Chiara; Rodgers, Christopher T; Maffei, Massimo E

    2015-11-30

    One of the most stimulating observations in plant evolution is a correlation between the occurrence of geomagnetic field (GMF) reversals (or excursions) and the moment of the radiation of Angiosperms. This led to the hypothesis that alterations in GMF polarity may play a role in plant evolution. Here, we describe a method to test this hypothesis by exposing Arabidopsis thaliana to artificially reversed GMF conditions. We used a three-axis magnetometer and the collected data were used to calculate the magnitude of the GMF. Three DC power supplies were connected to three Helmholtz coil pairs and were controlled by a computer to alter the GMF conditions. Plants grown in Petri plates were exposed to both normal and reversed GMF conditions. Sham exposure experiments were also performed. Exposed plants were photographed during the experiment and images were analyzed to calculate root length and leaf areas. Arabidopsis total RNA was extracted and Quantitative Real Time-PCR (qPCR) analyses were performed on gene expression of CRUCIFERIN 3 (CRU3), copper transport protein1 (COTP1), Redox Responsive Transcription Factor1 (RRTF1), Fe Superoxide Dismutase 1, (FSD1), Catalase3 (CAT3), Thylakoidal Ascorbate Peroxidase (TAPX), a cytosolic Ascorbate Peroxidase1 (APX1), and NADPH/respiratory burst oxidase protein D (RbohD). Four different reference genes were analysed to normalize the results of the qPCR. The best of the four genes was selected and the most stable gene for normalization was used. Our data show for the first time that reversing the GMF polarity using triaxial coils has significant effects on plant growth and gene expression. This supports the hypothesis that GMF reversal contributes to inducing changes in plant development that might justify a higher selective pressure, eventually leading to plant evolution.

  16. incurvata13, a Novel Allele of AUXIN RESISTANT6, Reveals a Specific Role for Auxin and the SCF Complex in Arabidopsis Embryogenesis, Vascular Specification, and Leaf Flatness1[W][OA

    PubMed Central

    Esteve-Bruna, David; Pérez-Pérez, José Manuel; Ponce, María Rosa; Micol, José Luis

    2013-01-01

    Auxin plays a pivotal role in plant development by modulating the activity of SCF ubiquitin ligase complexes. Here, we positionally cloned Arabidopsis (Arabidopsis thaliana) incurvata13 (icu13), a mutation that causes leaf hyponasty and reduces leaf venation pattern complexity and auxin responsiveness. We found that icu13 is a novel recessive allele of AUXIN RESISTANT6 (AXR6), which encodes CULLIN1, an invariable component of the SCF complex. Consistent with a role for auxin in vascular specification, the vascular defects in the icu13 mutant were accompanied by reduced expression of auxin transport and auxin perception markers in provascular cells. This observation is consistent with the expression pattern of AXR6, which we found to be restricted to vascular precursors and hydathodes in wild-type leaf primordia. AXR1, RELATED TO UBIQUITIN1-CONJUGATING ENZYME1, CONSTITUTIVE PHOTOMORPHOGENIC9 SIGNALOSOME5A, and CULLIN-ASSOCIATED NEDD8-DISSOCIATED1 participate in the covalent modification of CULLIN1 by RELATED TO UBIQUITIN. Hypomorphic alleles of these genes also display simple venation patterns, and their double mutant combinations with icu13 exhibited a synergistic, rootless phenotype reminiscent of that caused by loss of function of MONOPTEROS (MP), which forms an auxin-signaling module with BODENLOS (BDL). The phenotypes of double mutant combinations of icu13 with either a gain-of-function allele of BDL or a loss-of-function allele of MP were synergistic. In addition, a BDL:green fluorescent protein fusion protein accumulated in icu13, and BDL loss of function or MP overexpression suppressed the phenotype of icu13. Our results demonstrate that the MP-BDL module is required not only for root specification in embryogenesis and vascular postembryonic development but also for leaf flatness. PMID:23319550

  17. The Re-Establishment of Desiccation Tolerance in Germinated Arabidopsis thaliana Seeds and Its Associated Transcriptome

    PubMed Central

    Maia, Julio; Dekkers, Bas J. W.; Provart, Nicholas J.; Ligterink, Wilco; Hilhorst, Henk W. M.

    2011-01-01

    The combination of robust physiological models with “omics” studies holds promise for the discovery of genes and pathways linked to how organisms deal with drying. Here we used a transcriptomics approach in combination with an in vivo physiological model of re-establishment of desiccation tolerance (DT) in Arabidopsis thaliana seeds. We show that the incubation of desiccation sensitive (DS) germinated Arabidopsis seeds in a polyethylene glycol (PEG) solution re-induces the mechanisms necessary for expression of DT. Based on a SNP-tile array gene expression profile, our data indicates that the re-establishment of DT, in this system, is related to a programmed reversion from a metabolic active to a quiescent state similar to prior to germination. Our findings show that transcripts of germinated seeds after the PEG-treatment are dominated by those encoding LEA, seed storage and dormancy related proteins. On the other hand, a massive repression of genes belonging to many other classes such as photosynthesis, cell wall modification and energy metabolism occurs in parallel. Furthermore, comparison with a similar system for Medicago truncatula reveals a significant overlap between the two transcriptomes. Such overlap may highlight core mechanisms and key regulators of the trait DT. Taking into account the availability of the many genetic and molecular resources for Arabidopsis, the described system may prove useful for unraveling DT in higher plants. PMID:22195004

  18. Reproductive Toxicity and Life History Study of Silver Nanoparticle Effect, Uptake and Transport in Arabidopsis thaliana

    PubMed Central

    Geisler-Lee, Jane; Brooks, Marjorie; Gerfen, Jacob R.; Wang, Qiang; Fotis, Christin; Sparer, Anthony; Ma, Xingmao; Berg, R. Howard; Geisler, Matt

    2014-01-01

    Concerns about nanotechnology have prompted studies on how the release of these engineered nanoparticles impact our environment. Herein, the impact of 20 nm silver nanoparticles (AgNPs) on the life history traits of Arabidopsis thaliana was studied in both above- and below-ground parts, at macroscopic and microscopic scales. Both gross phenotypes (in contrast to microscopic phenotypes) and routes of transport and accumulation were investigated from roots to shoots. Wild type Arabidopsis growing in soil, regularly irrigated with 75 μg/L of AgNPs, did not show any obvious morphological change. However, their vegetative development was prolonged by two to three days and their reproductive growth shortened by three to four days. In addition, the germination rates of offspring decreased drastically over three generations. These findings confirmed that AgNPs induce abiotic stress and cause reproductive toxicity in Arabidopsis. To trace transport of AgNPs, this study also included an Arabidopsis reporter line genetically transformed with a green fluorescent protein and grown in an optical transparent medium with 75 μg/L AgNPs. AgNPs followed three routes: (1) At seven days after planting (DAP) at S1.0 (stages defined by Boyes et al. 2001 [41]), AgNPs attached to the surface of primary roots and then entered their root tips; (2) At 14 DAP at S1.04, as primary roots grew longer, AgNPs gradually moved into roots and entered new lateral root primordia and root hairs; (3) At 17 DAP at S1.06 when the Arabidopsis root system had developed multiple lateral roots, AgNPs were present in vascular tissue and throughout the whole plant from root to shoot. In some cases, if cotyledons of the Arabidopsis seedlings were immersed in melted transparent medium, then AgNPs were taken up by and accumulated in stomatal guard cells. These findings in Arabidopsis are the first to document specific routes and rates of AgNP uptake in vivo and in situ. PMID:28344224

  19. The transcription factor WIN1/SHN1 regulates Cutin biosynthesis in Arabidopsis thaliana.

    PubMed

    Kannangara, Rubini; Branigan, Caroline; Liu, Yan; Penfield, Teresa; Rao, Vijaya; Mouille, Grégory; Höfte, Herman; Pauly, Markus; Riechmann, José Luis; Broun, Pierre

    2007-04-01

    The composition and permeability of the cuticle has a large influence on its ability to protect the plant against various forms of biotic and abiotic stress. WAX INDUCER1 (WIN1) and related transcription factors have recently been shown to trigger wax production, enhance drought tolerance, and modulate cuticular permeability when overexpressed in Arabidopsis thaliana. We found that WIN1 influences the composition of cutin, a polyester that forms the backbone of the cuticle. WIN1 overexpression induces compositional changes and an overall increase in cutin production in vegetative and reproductive organs, while its downregulation has the opposite effect. Changes in cutin composition are preceded by the rapid and coordinated induction of several genes known or likely to be involved in cutin biosynthesis. This transcriptional response is followed after a delay by the induction of genes associated with wax biosynthesis, suggesting that the regulation of cutin and wax production by WIN1 is a two-step process. We demonstrate that at least one of the cutin pathway genes, which encodes long-chain acyl-CoA synthetase LACS2, is likely to be directly targeted by WIN1. Overall, our results suggest that WIN1 modulates cuticle permeability in Arabidopsis by regulating genes encoding cutin pathway enzymes.

  20. The Soybean GmNARK Affects ABA and Salt Responses in Transgenic Arabidopsis thaliana

    PubMed Central

    Cheng, Chunhong; Li, Changman; Wang, Diandong; Zhai, Lifeng; Cai, Zhaoming

    2018-01-01

    GmNARK (Glycine max nodule autoregulation receptor kinase) is the homolog of Arabidopsis thaliana CLAVATA1 (CLV1) and one of the most important regulators in the process of AON (Autoregulation of Nodulation), a process that restricts excessive nodule numbers in soybean. However, except for the function in AON, little is known about this gene. Here, we report that GmNARK plays important roles in process of plant response to abiotic stresses. Bioinformatic analysis and subcellular localization experiment results showed that GmNARK was a putative receptor like kinase and located at membrane. The promoter of GmNARK contains manifold cis regulatory elements that are responsive to hormone and stresses. Gene transcript expression pattern analysis in soybean revealed GmNARK was induced by ABA and NaCl treatment in both shoot and root. Overexpression of GmNARK in Arabidopsis resulted in higher sensitivity to ABA and salt treatment during seed germination and greening stages. We also checked the expression levels of some ABA response genes in the transgenic lines; the results showed that the transcript level of all the ABA response genes were much higher than that of wild type under ABA treatment. Our results revealed a novel role of GmNARK in response to abiotic stresses during plant growth and development. PMID:29720993

  1. The early inflorescence of Arabidopsis thaliana demonstrates positional effects in floral organ growth and meristem patterning.

    PubMed

    Plackett, Andrew R G; Powers, Stephen J; Phillips, Andy L; Wilson, Zoe A; Hedden, Peter; Thomas, Stephen G

    2018-06-01

    Linear modelling approaches detected significant gradients in organ growth and patterning across early flowers of the Arabidopsis inflorescence and uncovered evidence of new roles for gibberellin in floral development. Most flowering plants, including the genetic model Arabidopsis thaliana, produce multiple flowers in sequence from a reproductive shoot apex to form a flower spike (inflorescence). The development of individual flowers on an Arabidopsis inflorescence has typically been considered as highly stereotypical and uniform, but this assumption is contradicted by the existence of mutants with phenotypes visible in early flowers only. This phenomenon is demonstrated by mutants partially impaired in the biosynthesis of the phytohormone gibberellin (GA), in which floral organ growth is retarded in the first flowers to be produced but has recovered spontaneously by the 10th flower. We presently lack systematic data from multiple flowers across the Arabidopsis inflorescence to explain such changes. Using mutants of the GA 20-OXIDASE (GA20ox) GA biosynthesis gene family to manipulate endogenous GA levels, we investigated the dynamics of changing floral organ growth across the early Arabidopsis inflorescence (flowers 1-10). Modelling of floral organ lengths identified a significant, GA-independent gradient of increasing stamen length relative to the pistil in the wild-type inflorescence that was separable from other, GA-dependent effects. It was also found that the first flowers exhibited unstable organ patterning in contrast to later flowers and that this instability was prolonged by exogenous GA treatment. These findings indicate that the development of individual flowers is influenced by hitherto unknown factors acting across the inflorescence and also suggest novel functions for GA in floral patterning.

  2. Modeling the Metabolism of Arabidopsis thaliana: Application of Network Decomposition and Network Reduction in the Context of Petri Nets

    PubMed Central

    Koch, Ina; Nöthen, Joachim; Schleiff, Enrico

    2017-01-01

    Motivation: Arabidopsis thaliana is a well-established model system for the analysis of the basic physiological and metabolic pathways of plants. Nevertheless, the system is not yet fully understood, although many mechanisms are described, and information for many processes exists. However, the combination and interpretation of the large amount of biological data remain a big challenge, not only because data sets for metabolic paths are still incomplete. Moreover, they are often inconsistent, because they are coming from different experiments of various scales, regarding, for example, accuracy and/or significance. Here, theoretical modeling is powerful to formulate hypotheses for pathways and the dynamics of the metabolism, even if the biological data are incomplete. To develop reliable mathematical models they have to be proven for consistency. This is still a challenging task because many verification techniques fail already for middle-sized models. Consequently, new methods, like decomposition methods or reduction approaches, are developed to circumvent this problem. Methods: We present a new semi-quantitative mathematical model of the metabolism of Arabidopsis thaliana. We used the Petri net formalism to express the complex reaction system in a mathematically unique manner. To verify the model for correctness and consistency we applied concepts of network decomposition and network reduction such as transition invariants, common transition pairs, and invariant transition pairs. Results: We formulated the core metabolism of Arabidopsis thaliana based on recent knowledge from literature, including the Calvin cycle, glycolysis and citric acid cycle, glyoxylate cycle, urea cycle, sucrose synthesis, and the starch metabolism. By applying network decomposition and reduction techniques at steady-state conditions, we suggest a straightforward mathematical modeling process. We demonstrate that potential steady-state pathways exist, which provide the fixed carbon to

  3. Non-Photochemical Quenching Capacity in Arabidopsis thaliana Affects Herbivore Behaviour

    PubMed Central

    Johansson Jänkänpää, Hanna; Frenkel, Martin; Zulfugarov, Ismayil; Reichelt, Michael; Krieger-Liszkay, Anja; Mishra, Yogesh; Gershenzon, Jonathan; Moen, Jon; Lee, Choon-Hwan; Jansson, Stefan

    2013-01-01

    Under natural conditions, plants have to cope with numerous stresses, including light-stress and herbivory. This raises intriguing questions regarding possible trade-offs between stress defences and growth. As part of a program designed to address these questions we have compared herbivory defences and damage in wild type Arabidopsis thaliana and two “photoprotection genotypes”, npq4 and oePsbS, which respectively lack and overexpress PsbS (a protein that plays a key role in qE-type non-photochemical quenching). In dual-choice feeding experiments both a specialist (Plutella xylostella) and a generalist (Spodoptera littoralis) insect herbivore preferred plants that expressed PsbS most strongly. In contrast, although both herbivores survived equally well on each of the genotypes, for oviposition female P. xylostella adults preferred plants that expressed PsbS least strongly. However, there were no significant differences between the genotypes in levels of the 10 most prominent glucosinolates; key substances in the Arabidopsis anti-herbivore chemical defence arsenal. After transfer from a growth chamber to the field we detected significant differences in the genotypes’ metabolomic profiles at all tested time points, using GC-MS, but no consistent “metabolic signature” for the lack of PsbS. These findings suggest that the observed differences in herbivore preferences were due to differences in the primary metabolism of the plants rather than their contents of typical “defence compounds”. A potentially significant factor is that superoxide accumulated most rapidly and to the highest levels under high light conditions in npq4 mutants. This could trigger changes in planta that are sensed by herbivores either directly or indirectly, following its dismutation to H2O2. PMID:23301046

  4. Peculiarities of genital organ formation in Arabidopsis thaliana (L) Heynh. under spaceflight conditions

    NASA Astrophysics Data System (ADS)

    Kordyum, E. L.; Sytnik, K. M.; Chernyaeva, I. I.

    An experiment was carried out aboard the Salyut 6 research orbital station on Arabidopsis thaliana cultivations. The seeds were sprouted in the Svetoblok 1 device which provides for plant growth in the agar medium under sterile conditions and at 4000 lux illumination. The experimental plants, as well as the controls, reached approximately the same developmental stages: both flowered and began to bear fruit. A microscopic examination of the generative organs in the control and experimental plants shows that in normally formed (by appearance) flower buds and flowers of the experimental plants, as distinct from the controls, there were no fertile elements of the adroecium and gynoecium. Degeneration of the latter occurred at different stages of generative organ development. Possible reasons for this phenomenon in plants grown under weightless conditions are considered.

  5. MEDIATOR18 and MEDIATOR20 confer susceptibility to Fusarium oxysporum in Arabidopsis thaliana

    PubMed Central

    Stiller, Jiri; Davoine, Celine; Björklund, Stefan; Manners, John M.; Kazan, Kemal; Schenk, Peer M.

    2017-01-01

    The conserved protein complex known as Mediator conveys transcriptional signals by acting as an intermediary between transcription factors and RNA polymerase II. As a result, Mediator subunits play multiple roles in regulating developmental as well as abiotic and biotic stress pathways. In this report we identify the head domain subunits MEDIATOR18 and MEDIATOR20 as important susceptibility factors for Fusarium oxysporum infection in Arabidopsis thaliana. Mutants of MED18 and MED20 display down-regulation of genes associated with jasmonate signaling and biosynthesis while up-regulation of salicylic acid associated pathogenesis related genes and reactive oxygen producing and scavenging genes. We propose that MED18 and MED20 form a sub-domain within Mediator that controls the balance of salicylic acid and jasmonate associated defense pathways. PMID:28441405

  6. Identification of new aromatic cytokinins in Arabidopsis thaliana and Populus x canadensis leaves by LC-(+)ESI-MS and capillary liquid chromatography/frit-fast atom bombardment mass spectrometry.

    PubMed

    Tarkowská, Danuse; Dolezal, Karel; Tarkowski, Petr; Astot, Crister; Holub, Jan; Fuksová, Kvetoslava; Schmülling, Thomas; Sandberg, Göran; Strnad, Miroslav

    2003-04-01

    A search for naturally occurring aromatic cytokinins (ARCKs) in Arabidopsis thaliana plants and Populus x canadensis leaves led to the discovery of four new plant hormone substances: 6-(2-methoxybenzylamino)purine (ortho-methoxytopolin, MeoT), 6-(3-methoxybenzylamino)purine (meta-methoxytopolin, MemT) (Fig. 1) and their 9-beta-D-ribofuranosyl derivatives. These substances were identified by liquid chromatography electrospray ionization mass spectrometry [LC (+)ESI-MS] and capillary-liquid chromatography/frit-fast atom bombardment-mass spectrometry [CapLC/frit-FAB-MS] after pre-column derivatization. The chemical structures were subsequently confirmed by chemical synthesis. Because of lack of heavy labelled internal standards, the endogenous levels of methoxytopolins in A. thaliana plants, Populus x canadensis leaves and samples derived from cultures of Agrobacterium tumefaciens strain GV3101 were determined by enzyme-linked immunosorbent assay (ELISA) of HPLC-fractionated extracts. While the levels of MeoT, MemT and their ribosides in A. thaliana shoots and Populus x canadensis leaves were relatively low (approximately 0.25-10 pmol g-1 FW for MeoT and MemT, respectively), the A. tumefaciens strain produced up to 600 times more of the newly identified substances. Cytokinin activity of methoxytopolines was demonstrated in three bioassays testing their ability to stimulate tobacco callus growth, to delay chlorophyll degradation in excised wheat leaves, and to induce betacyanin synthesis in Amaranthus caudatus var. atropurpurea cotyledons. Notably, their anti-senescing activity in the wheat leaf assay exceeded that of BAP and Z by almost 200%. Methoxytopolins are proposed to be new members of the biologically active aromatic cytokinin family, which might have specific physiological functions.

  7. Intracellular ca2+ stores could participate to abscisic acid-induced depolarization and stomatal closure in Arabidopsis thaliana

    PubMed Central

    Meimoun, Patrice; Vidal, Guillaume; Bohrer, Anne-Sophie; Lehner, Arnaud; Tran, Daniel; Briand, Joël; Bouteau, François

    2009-01-01

    In Arabidopsis thaliana cell suspension,abscisic acid (aBa) induces changes in cytosolic calcium concentration ([Ca2+]cyt) which are the trigger for aBa-induced plasma membrane anion current activation, H+-aTPase inhibition, and subsequent plasma membrane depolarization. In the present study, we took advantage of this model to analyze the implication of intracellular Ca2+ stores in aBa signal transduction through electrophysiological current measurements, cytosolic Ca2+ activity measurements with the apoaequorin Ca2+ reporter protein and external pH measurement. Intracellular Ca2+ stores involvement was determined by using specific inhibitors of CICR channels: the cADP-ribose/ryanodine receptor (Br-cADPR and dantrolene) and of the inositol trisphosphate receptor (U73122). In addition experiments were performed on epidermal strips of A. thaliana leaves to monitor stomatal closure in response to ABA in presence of the same pharmacology. Our data provide evidence that ryanodine receptor and inositol trisphosphate receptor could be involved in ABA-induced (1) Ca2+ release in the cytosol, (2) anion channel activation and H+-ATPase inhibition leading to plasma membrane depolarization and (3) stomatal closure. Intracellular Ca2+ release could thus contribute to the control of early events in the ABA signal transduction pathway in A. thaliana. PMID:19847112

  8. Expression of a nitric oxide degrading enzyme induces a senescence programme in Arabidopsis.

    PubMed

    Mishina, Tatiana E; Lamb, Chris; Zeier, Jürgen

    2007-01-01

    Nitric oxide (NO) has been proposed to act as a factor delaying leaf senescence and fruit maturation in plants. Here we show that expression of a NO degrading dioxygenase (NOD) in Arabidopsis thaliana initiates a senescence-like phenotype, an effect that proved to be more pronounced in older than in younger leaves. This senescence phenotype was preceded by a massive switch in gene expression in which photosynthetic genes were down-regulated, whereas many senescence-associated genes (SAGs) and the 1-aminocyclopropane-1-carboxylic acid (ACC) synthase gene ACS6 involved in ethylene synthesis were up-regulated. External fumigation of NOD plants with NO as well as environmental conditions known to stimulate endogenous NO production attenuated the induced senescence programme. For instance, both high light conditions and nitrate feeding reduced the senescence phenotype and attenuated the down-regulation of photosynthetic genes as well as the up-regulation of SAGs. Treatment of plants with the cytokinin 6-benzylaminopurin (BAP) reduced the down-regulation of photosynthesis, although it had no consistent effect on SAG expression. Metabolic changes during NOD-induced senescence comprehended increases in salicylic acid (SA) levels, accumulation of the phytoalexin camalexin and elevation of leaf gamma-tocopherol contents, all of which occurred during natural senescence in Arabidopsis leaves as well. Moreover, NO fumigation delayed the senescence process induced by darkening individual Arabidopsis Columbia-0 (Col-0) leaves. Our data thus support the notion that NO acts as a negative regulator of leaf senescence.

  9. Subcellular Distribution of Glutathione Precursors in Arabidopsis thaliana

    PubMed Central

    Koffler, Barbara Eva; Maier, Romana; Zechmann, Bernd

    2011-01-01

    Abstract Glutathione is an important antioxidant and has many important functions in plant development, growth and defense. Glutathione synthesis and degradation is highly compartment-specific and relies on the subcellular availability of its precursors, cysteine, glutamate, glycine and γ-glutamylcysteine especially in plastids and the cytosol which are considered as the main centers for glutathione synthesis. The availability of glutathione precursors within these cell compartments is therefore of great importance for successful plant development and defense. The aim of this study was to investigate the compartment-specific importance of glutathione precursors in Arabidopsis thaliana. The subcellular distribution was compared between wild type plants (Col-0), plants with impaired glutathione synthesis (glutathione deficient pad2-1 mutant, wild type plants treated with buthionine sulfoximine), and one complemented line (OE3) with restored glutathione synthesis. Immunocytohistochemistry revealed that the inhibition of glutathione synthesis induced the accumulation of the glutathione precursors cysteine, glutamate and glycine in most cell compartments including plastids and the cytosol. A strong decrease could be observed in γ-glutamylcysteine (γ-EC) contents in these cell compartments. These experiments demonstrated that the inhibition of γ-glutamylcysteine synthetase (GSH1) – the first enzyme of glutathione synthesis – causes a reduction of γ-EC levels and an accumulation of all other glutathione precursors within the cells. PMID:22050910

  10. INCURVATA2 Encodes the Catalytic Subunit of DNA Polymerase α and Interacts with Genes Involved in Chromatin-Mediated Cellular Memory in Arabidopsis thaliana

    PubMed Central

    Barrero, José María; González-Bayón, Rebeca; del Pozo, Juan Carlos; Ponce, María Rosa; Micol, José Luis

    2007-01-01

    Cell type–specific gene expression patterns are maintained by the stable inheritance of transcriptional states through mitosis, requiring the action of multiprotein complexes that remodel chromatin structure. Genetic and molecular interactions between chromatin remodeling factors and components of the DNA replication machinery have been identified in Schizosaccharomyces pombe, indicating that some epigenetic marks are replicated simultaneously to DNA with the participation of the DNA replication complexes. This model of epigenetic inheritance might be extended to the plant kingdom, as we report here with the positional cloning and characterization of INCURVATA2 (ICU2), which encodes the putative catalytic subunit of the DNA polymerase α of Arabidopsis thaliana. The strong icu2-2 and icu2-3 insertional alleles caused fully penetrant zygotic lethality when homozygous and incompletely penetrant gametophytic lethality, probably because of loss of DNA polymerase activity. The weak icu2-1 allele carried a point mutation and caused early flowering, leaf incurvature, and homeotic transformations of sepals into carpels and of petals into stamens. Further genetic analyses indicated that ICU2 interacts with TERMINAL FLOWER2, the ortholog of HETEROCHROMATIN PROTEIN1 of animals and yeasts, and with the Polycomb group (PcG) gene CURLY LEAF. Another PcG gene, EMBRYONIC FLOWER2, was found to be epistatic to ICU2. Quantitative RT-PCR analyses indicated that a number of regulatory genes were derepressed in the icu2-1 mutant, including genes associated with flowering time, floral meristem, and floral organ identity. PMID:17873092

  11. Water Deficit Enhances C Export to the Roots in Arabidopsis thaliana Plants with Contribution of Sucrose Transporters in Both Shoot and Roots1[OPEN

    PubMed Central

    Durand, Mickaël; Porcheron, Benoît; Maurousset, Laurence; Lemoine, Rémi; Pourtau, Nathalie

    2016-01-01

    Root high plasticity is an adaptation to its changing environment. Water deficit impairs growth, leading to sugar accumulation in leaves, part of which could be available to roots via sucrose (Suc) phloem transport. Phloem loading is widely described in Arabidopsis (Arabidopsis thaliana), while unloading in roots is less understood. To gain information on leaf-to-root transport, a soil-based culture system was developed to monitor root system architecture in two dimensions. Under water deficit (50% of soil water-holding capacity), total root length was strongly reduced but the depth of root foraging and the shape of the root system were less affected, likely to improve water uptake. 14CO2 pulse-chase experiments confirmed that water deficit enhanced carbon (C) export to the roots, as suggested by the increased root-to-shoot ratio. The transcript levels of AtSWEET11 (for sugar will eventually be exported transporter), AtSWEET12, and AtSUC2 (for Suc carrier) genes, all three involved in Suc phloem loading, were significantly up-regulated in leaves of water deficit plants, in accordance with the increase in C export from the leaves to the roots. Interestingly, the transcript levels of AtSUC2 and AtSWEET11 to AtSWEET15 were also significantly higher in stressed roots, underlying the importance of Suc apoplastic unloading in Arabidopsis roots and a putative role for these Suc transporters in Suc unloading. These data demonstrate that, during water deficit, plants respond to growth limitation by allocating relatively more C to the roots to maintain an efficient root system and that a subset of Suc transporters is potentially involved in the flux of C to and in the roots. PMID:26802041

  12. Impaired pH Homeostasis in Arabidopsis Lacking the Vacuolar Dicarboxylate Transporter and Analysis of Carboxylic Acid Transport across the Tonoplast1

    PubMed Central

    Hurth, Marco Alois; Suh, Su Jeoung; Kretzschmar, Tobias; Geis, Tina; Bregante, Monica; Gambale, Franco; Martinoia, Enrico; Neuhaus, H. Ekkehard

    2005-01-01

    Arabidopsis (Arabidopsis thaliana) mutants lacking the tonoplastic malate transporter AttDT (A. thaliana tonoplast dicarboxylate transporter) and wild-type plants showed no phenotypic differences when grown under standard conditions. To identify putative metabolic changes in AttDT knock-out plants, we provoked a metabolic scenario connected to an increased consumption of dicarboxylates. Acidification of leaf discs stimulated dicarboxylate consumption and led to extremely low levels of dicarboxylates in mutants. To investigate whether reduced dicarboxylate concentrations in mutant leaf cells and, hence, reduced capacity to produce OH− to overcome acidification might affect metabolism, we measured photosynthetic oxygen evolution under conditions where the cytosol is acidified. AttDT::tDNA protoplasts showed a much stronger inhibition of oxygen evolution at low pH values when compared to wild-type protoplasts. Apparently citrate, which is present in higher amounts in knock-out plants, is not able to replace dicarboxylates to overcome acidification. To raise more information on the cellular level, we performed localization studies of carboxylates. Although the total pool of carboxylates in mutant vacuoles was nearly unaltered, these organelles contained a lower proportion of malate and fumarate and a higher proportion of citrate when compared to wild-type vacuoles. These alterations concur with the observation that radioactively labeled malate and citrate are transported into Arabidopsis vacuoles by different carriers. In addition, wild-type vacuoles and corresponding organelles from AttDT::tDNA mutants exhibited similar malate channel activities. In conclusion, these results show that Arabidopsis vacuoles contain at least two transporters and a channel for dicarboxylates and citrate and that the activity of AttDT is critical for regulation of pH homeostasis. PMID:15728336

  13. Light responses in Photoperiodism in Arabidopsis thaliana

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

    Anthony R. Cashmore

    2006-08-01

    phyB. Nature 410, 487-490. Jarillo, J. A., Gabrys, H., Capel, J., Alonso, J. M., Ecker, J. R., and Cashmore, A. R. (2001b). Phototropin-related NPL1 controls chloroplast relocation induced by blue light. Nature 410, 952-954. Kinoshita, T., Doi, M., Suetsugu, N., Kagawa, T., Wada, M., and Shimazaki Ki, K. (2001). phot1 and phot2 mediate blue light regulation of stomatal opening. Nature 414, 656-660. Mas, P., Kim, W. Y., Somers, D. E., and Kay, S. A. (2003). Targeted degradation of TOC1 by ZTL modulates circadian function in Arabidopsis thaliana. Nature 426, 567-570.« less

  14. Induction of Nickel Accumulation in Response to Zinc Deficiency in Arabidopsis thaliana

    PubMed Central

    Nishida, Sho; Kato, Aki; Tsuzuki, Chisato; Yoshida, Junko; Mizuno, Takafumi

    2015-01-01

    Excessive accumulation of nickel (Ni) can be toxic to plants. In Arabidopsis thaliana, the Fe2+ transporter, iron (Fe)-regulated transporter1 (IRT1), mediates Fe uptake and also implicates in Ni2+ uptake at roots; however, the underlying mechanism of Ni2+ uptake and accumulation remains unelucidated. In the present study, we found that zinc (Zn) deficient conditions resulted in increased accumulation of Ni in plants, particularly in roots, in A. thaliana. In order to elucidate the underlying mechanisms of Ni uptake correlating zinc condition, we traced 63Ni isotope in response to Zn and found that (i) Zn deficiency induces short-term Ni2+ absorption and (ii) Zn2+ inhibits Ni2+ uptake, suggesting competitive uptake between Ni and Zn. Furthermore, the Zrt/Irt-like protein 3 (ZIP3)-defective mutant with an elevated Zn-deficient response exhibited higher Ni accumulation than the wild type, further supporting that the response to Zn deficiency induces Ni accumulation. Previously, expression profile study demonstrated that IRT1 expression is not inducible by Zn deficiency. In the present study, we found increased Ni accumulation in IRT1-null mutant under Zn deficiency in agar culture. These suggest that Zn deficiency induces Ni accumulation in an IRT1-independen manner. The present study revealed that Ni accumulation is inducible in response to Zn deficiency, which may be attributable to a Zn uptake transporter induced by Zn deficiency. PMID:25923075

  15. Bacillus subtilis Early Colonization of Arabidopsis thaliana Roots Involves Multiple Chemotaxis Receptors

    PubMed Central

    Allard-Massicotte, Rosalie; Tessier, Laurence; Lécuyer, Frédéric; Lakshmanan, Venkatachalam; Lucier, Jean-François; Garneau, Daniel; Caudwell, Larissa; Vlamakis, Hera; Bais, Harsh P.

    2016-01-01

    ABSTRACT Colonization of plant roots by Bacillus subtilis is mutually beneficial to plants and bacteria. Plants can secrete up to 30% of their fixed carbon via root exudates, thereby feeding the bacteria, and in return the associated B. subtilis bacteria provide the plant with many growth-promoting traits. Formation of a biofilm on the root by matrix-producing B. subtilis is a well-established requirement for long-term colonization. However, we observed that cells start forming a biofilm only several hours after motile cells first settle on the plant. We also found that intact chemotaxis machinery is required for early root colonization by B. subtilis and for plant protection. Arabidopsis thaliana root exudates attract B. subtilis in vitro, an activity mediated by the two characterized chemoreceptors, McpB and McpC, as well as by the orphan receptor TlpC. Nonetheless, bacteria lacking these chemoreceptors are still able to colonize the root, suggesting that other chemoreceptors might also play a role in this process. These observations suggest that A. thaliana actively recruits B. subtilis through root-secreted molecules, and our results stress the important roles of B. subtilis chemoreceptors for efficient colonization of plants in natural environments. These results demonstrate a remarkable strategy adapted by beneficial rhizobacteria to utilize carbon-rich root exudates, which may facilitate rhizobacterial colonization and a mutualistic association with the host. PMID:27899502

  16. Accumulation of eicosapolyenoic acids enhances sensitivity to abscisic acid and mitigates the effects of drought in transgenic Arabidopsis thaliana

    PubMed Central

    Qi, Baoxiu

    2014-01-01

    IgASE1, a C18 Δ9-specific polyunsaturated fatty acid elongase from the marine microalga Isochrysis galbana, is able to convert linoleic acid and α-linolenic acid to eicosadienoic acid and eicosatrienoic acid in Arabidopsis. Eicosadienoic acid and eicosatrienoic acid are precursors of arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid, which are synthesized via the Δ8 desaturation biosynthetic pathways. This study shows that the IgASE1-expressing transgenic Arabidopsis exhibited altered morphology (decreased leaf area and biomass) and enhanced drought resistance compared to wild-type plants. The transgenic Arabidopsis were hypersensitive to abscisic acid (ABA) during seed germination, post-germination growth, and seedling development. They had elevated leaf ABA levels under well-watered and dehydrated conditions and their stomata were more sensitive to ABA. Exogenous application of eicosadienoic acid and eicosatrienoic acid can mimic ABA and drought responses in the wild type plants, similar to that found in the transgenic ones. The transcript levels of genes involved in the biosynthesis of ABA (NCED3, ABA1, AAO3) as well as other stress-related genes were upregulated in this transgenic line upon osmotic stress (300mM mannitol). Taken together, these results indicate that these two eicosapolyenoic acids or their derived metabolites can mitigate the effects of drought in transgenic Arabidopsis, at least in part, through the action of ABA. PMID:24609499

  17. Accumulation of eicosapolyenoic acids enhances sensitivity to abscisic acid and mitigates the effects of drought in transgenic Arabidopsis thaliana.

    PubMed

    Yuan, Xiaowei; Li, Yaxiao; Liu, Shiyang; Xia, Fei; Li, Xinzheng; Qi, Baoxiu

    2014-04-01

    IgASE1, a C₁₈ Δ(9)-specific polyunsaturated fatty acid elongase from the marine microalga Isochrysis galbana, is able to convert linoleic acid and α-linolenic acid to eicosadienoic acid and eicosatrienoic acid in Arabidopsis. Eicosadienoic acid and eicosatrienoic acid are precursors of arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid, which are synthesized via the Δ(8) desaturation biosynthetic pathways. This study shows that the IgASE1-expressing transgenic Arabidopsis exhibited altered morphology (decreased leaf area and biomass) and enhanced drought resistance compared to wild-type plants. The transgenic Arabidopsis were hypersensitive to abscisic acid (ABA) during seed germination, post-germination growth, and seedling development. They had elevated leaf ABA levels under well-watered and dehydrated conditions and their stomata were more sensitive to ABA. Exogenous application of eicosadienoic acid and eicosatrienoic acid can mimic ABA and drought responses in the wild type plants, similar to that found in the transgenic ones. The transcript levels of genes involved in the biosynthesis of ABA (NCED3, ABA1, AAO3) as well as other stress-related genes were upregulated in this transgenic line upon osmotic stress (300 mM mannitol). Taken together, these results indicate that these two eicosapolyenoic acids or their derived metabolites can mitigate the effects of drought in transgenic Arabidopsis, at least in part, through the action of ABA.

  18. A direct screening procedure for gravitropism mutants in Arabidopsis thaliana (L.) Heynh

    NASA Technical Reports Server (NTRS)

    Bullen, B. L.; Best, T. R.; Gregg, M. M.; Poff, K. L.; Barsel, S-E (Principal Investigator)

    1990-01-01

    In order to isolate gravitropism mutants of Arabidopsis thaliana (L.) Heynh. var Estland for the genetic dissection of the gravitropism pathway, a direct screening procedure has been developed in which mutants are selected on the basis of their gravitropic response. Variability in hypocotyl curvature was dependent on the germination time of each seed stock, resulting in the incorrect identification of several lines as gravitropism mutants when a standard protocol for the potentiation of germination was used. When the protocol was adjusted to allow for differences in germination time, these lines were eliminated from the collection. Out of the 60,000 M2 seedlings screened, 0.3 to 0.4% exhibited altered gravitropism. In approximately 40% of these mutant lines, only gravitropism by the root or the hypocotyl was altered, while the response of the other organ was unaffected. These data support the hypothesis that root and hypocotyl gravitropism are genetically separable.

  19. Cyclic nucleotide binding proteins in the Arabidopsis thaliana and Oryza sativa genomes

    PubMed Central

    Bridges, Dave; Fraser, Marie E; Moorhead, Greg BG

    2005-01-01

    Background Cyclic nucleotides are ubiquitous intracellular messengers. Until recently, the roles of cyclic nucleotides in plant cells have proven difficult to uncover. With an understanding of the protein domains which can bind cyclic nucleotides (CNB and GAF domains) we scanned the completed genomes of the higher plants Arabidopsis thaliana (mustard weed) and Oryza sativa (rice) for the effectors of these signalling molecules. Results Our analysis found that several ion channels and a class of thioesterases constitute the possible cyclic nucleotide binding proteins in plants. Contrary to some reports, we found no biochemical or bioinformatic evidence for a plant cyclic nucleotide regulated protein kinase, suggesting that cyclic nucleotide functions in plants have evolved differently than in mammals. Conclusion This paper provides a molecular framework for the discussion of cyclic nucleotide function in plants, and resolves a longstanding debate about the presence of a cyclic nucleotide dependent kinase in plants. PMID:15644130

  20. Ectopic expression of different cytokinin-regulated transcription factor genes of Arabidopsis thaliana alters plant growth and development.

    PubMed

    Köllmer, Ireen; Werner, Tomáš; Schmülling, Thomas

    2011-08-15

    The plant hormone cytokinin rapidly alters the steady state transcript levels of a number of transcription factor genes suggesting that these might have a function in mediating cytokinin effects. Here we report the analysis of Arabidopsis thaliana plants with an altered expression level of four different cytokinin-regulated transcription factor genes. These include GATA22 (also known as CGA1/GNL), two genes coding for members of the homeodomain zip (HD zip) class II transcription factor family (HAT4, HAT22), and bHLH64. Ectopic expression of the GATA22 gene induced the development of chloroplasts in root tissue where it is normally suppressed and led to the formation of shorter and less branched roots. Overexpression of HAT22 lowered the seedlings chlorophyll content and caused an earlier onset of leaf senescence. Enhanced expression of the HAT4 gene led to severe defects in inflorescence stem development and to a decrease in root growth and branching, while hat4 insertional mutants developed a larger root system. 35S:bHLH64 transgenic plants showed a pleiotropic phenotype, consisting of larger rosettes, reduced chlorophyll content and an elongated and thickened hypocotyl. Flower development was strongly disturbed leading to sterile plants. The results are consistent with specific functions of these transcription factor genes in regulating part of the cytokinin activities and suggest their action as convergence point with other signalling pathways, particularly those of gibberellin and light. Copyright © 2011 Elsevier GmbH. All rights reserved.

  1. TMV-Cg Coat Protein stabilizes DELLA proteins and in turn negatively modulates salicylic acid-mediated defense pathway during Arabidopsis thaliana viral infection.

    PubMed

    Rodriguez, Maria Cecilia; Conti, Gabriela; Zavallo, Diego; Manacorda, Carlos Augusto; Asurmendi, Sebastian

    2014-08-03

    Plant viral infections disturb defense regulatory networks during tissue invasion. Emerging evidence demonstrates that a significant proportion of these alterations are mediated by hormone imbalances. Although the DELLA proteins have been reported to be central players in hormone cross-talk, their role in the modulation of hormone signaling during virus infections remains unknown. This work revealed that TMV-Cg coat protein (CgCP) suppresses the salicylic acid (SA) signaling pathway without altering defense hormone SA or jasmonic acid (JA) levels in Arabidopsis thaliana. Furthermore, it was observed that the expression of CgCP reduces plant growth and delays the timing of floral transition. Quantitative RT-qPCR analysis of DELLA target genes showed that CgCP alters relative expression of several target genes, indicating that the DELLA proteins mediate transcriptional changes produced by CgCP expression. Analyses by fluorescence confocal microscopy showed that CgCP stabilizes DELLA proteins accumulation in the presence of gibberellic acid (GA) and that the DELLA proteins are also stabilized during TMV-Cg virus infections. Moreover, DELLA proteins negatively modulated defense transcript profiles during TMV-Cg infection. As a result, TMV-Cg accumulation was significantly reduced in the quadruple-DELLA mutant Arabidopsis plants compared to wild type plants. Taken together, these results demonstrate that CgCP negatively regulates the salicylic acid-mediated defense pathway by stabilizing the DELLA proteins during Arabidopsis thaliana viral infection, suggesting that CgCP alters the stability of DELLAs as a mechanism of negative modulation of antiviral defense responses.

  2. Ultraviolet-B- and ozone-induced biochemical changes in antioxidant enzymes of Arabidopsis thaliana.

    PubMed Central

    Rao, M V; Paliyath, G; Ormrod, D P

    1996-01-01

    Earlier studies with Arabidopsis thaliana exposed to ultraviolet B (UV-B) and ozone (O3) have indicated the differential responses of superoxide dismutase and glutathione reductase. In this study, we have investigated whether A. thaliana genotype Landsberg erecta and its flavonoid-deficient mutant transparent testa (tt5) is capable of metabolizing UV-B- and O3-induced activated oxygen species by invoking similar antioxidant enzymes. UV-B exposure preferentially enhanced guaiacol-peroxidases, ascorbate peroxidase, and peroxidases specific to coniferyl alcohol and modified the substrate affinity of ascorbate peroxidase. O3 exposure enhanced superoxide dismutase, peroxidases, glutathione reductase, and ascorbate peroxidase to a similar degree and modified the substrate affinity of both glutathione reductase and ascorbate peroxidase. Both UV-B and O3 exposure enhanced similar Cu,Zn-superoxide dismutase isoforms. New isoforms of peroxidases and ascorbate peroxidase were synthesized in tt5 plants irradiated with UV-B. UV-B radiation, in contrast to O3, enhanced the activated oxygen species by increasing membrane-localized NADPH-oxidase activity and decreasing catalase activities. These results collectively suggest that (a) UV-B exposure preferentially induces peroxidase-related enzymes, whereas O3 exposure invokes the enzymes of superoxide dismutase/ascorbate-glutathione cycle, and (b) in contrast to O3, UV-B exposure generated activated oxygen species by increasing NADPH-oxidase activity. PMID:8587977

  3. Sinapic acid or its derivatives interfere with abscisic acid homeostasis during Arabidopsis thaliana seed germination.

    PubMed

    Bi, Baodi; Tang, Jingliang; Han, Shuang; Guo, Jinggong; Miao, Yuchen

    2017-06-06

    Sinapic acid and its esters have broad functions in different stages of seed germination and plant development and are thought to play a role in protecting against ultraviolet irradiation. To better understand the interactions between sinapic acid esters and seed germination processes in response to various stresses, we analyzed the role of the plant hormone abscisic acid (ABA) in the regulation of sinapic acid esters involved in seed germination and early seedling growth. We found that exogenous sinapic acid promotes seed germination in a dose-dependent manner in Arabidopsis thaliana. High-performance liquid chromatography mass spectrometry analysis showed that exogenous sinapic acid increased the sinapoylcholine content of imbibed seeds. Furthermore, sinapic acid affected ABA catabolism, resulting in reduced ABA levels and increased levels of the ABA-glucose ester. Using mutants deficient in the synthesis of sinapate esters, we showed that the germination of mutant sinapoylglucose accumulator 2 (sng2) and bright trichomes 1 (brt1) seeds was more sensitive to ABA than the wild-type. Moreover, Arabidopsis mutants deficient in either abscisic acid deficient 2 (ABA2) or abscisic acid insensitive 3 (ABI3) displayed increased expression of the sinapoylglucose:choline sinapoyltransferase (SCT) and sinapoylcholine esterase (SCE) genes with sinapic acid treatment. This treatment also affected the accumulation of sinapoylcholine and free choline during seed germination. We demonstrated that sinapoylcholine, which constitutes the major phenolic component in seeds among various minor sinapate esters, affected ABA homeostasis during seed germination and early seedling growth in Arabidopsis. Our findings provide insights into the role of sinapic acid and its esters in regulating ABA-mediated inhibition of Arabidopsis seed germination in response to drought stress.

  4. Impact of CCR1 silencing on the assembly of lignified secondary walls in Arabidopsis thaliana.

    PubMed

    Ruel, Katia; Berrio-Sierra, Jimmy; Derikvand, Mohammad Mir; Pollet, Brigitte; Thévenin, Johanne; Lapierre, Catherine; Jouanin, Lise; Joseleau, Jean-Paul

    2009-01-01

    A cinnamoyl-CoA reductase 1 knockout mutant in Arabidopsis thaliana was investigated for the consequences of lignin synthesis perturbation on the assembly of the cell walls. The mutant displayed a dwarf phenotype and a strong collapse of its xylem vessels corresponding to lower lignin content and a loss of lignin units of the noncondensed type. Transmission electron microscopy revealed that the transformation considerably impaired the capacity of interfascicular fibers and vascular bundles to complete the assembly of cellulose microfibrils in the S(2) layer, the S(1) layer remaining unaltered. Such disorder in cellulose was correlated with X-ray diffraction showing altered organization. Semi-quantitative immunolabeling of lignins showed that the patterns of distribution were differentially affected in interfascicular fibers and vascular bundles, pointing to the importance of noncondensed lignin structures for the assembly of a coherent secondary wall. The use of laser capture microdissection combined with the microanalysis of lignins and polysaccharides allowed these polymers to be characterized into specific cell types. Wild-type A. thaliana displayed a two-fold higher syringyl to guaiacyl ratio in interfascicular fibers compared with vascular bundles, whereas this difference was less marked in the cinnamoyl-CoA reductase 1 knockout mutant.

  5. A fluorescent reporter protein containing AtRMR1 domains is targeted to the storage and central vacuoles in Arabidopsis thaliana and tobacco leaf cells.

    PubMed

    Scabone, Camila María; Frigerio, Lorenzo; Petruccelli, Silvana

    2011-10-01

    To develop a new strategy to target recombinant proteins to the vacuolar storage system in transgenic plants, the ability of the transmembrane and cytosolic domains of Arabidopsis receptor homology-transmembrane-RING H2-1 (AtRMR1) was evaluated. A secreted version of RFP (secRFP) and a fusion of it to the transmembrane and cytosolic domains of AtRMR1 (RFP-TMCT) were produced and studied both in transient and stable expression assays. Transient expression in leaves of Nicotiana tabacum showed that secRFP is secreted to the apoplast while its fusion to TMCT of AtRMR1 is sufficient to prevent secretion of the reporter. In tobacco leaves, RFP-TMCT reporter showed an endoplasmic reticulum pattern in early expression stages while in late expression stages, it was found in the vacuolar lumen. For the first time, the role of TM and CT domains of AtRMR1 in stable expression in Arabidopsis thaliana is presented; the fusion of TMCT to secRFP is sufficient to sort RFP to the lumen of the central vacuoles in leaves and roots and to the lumen of PSV in cotyledons of mature embryos. In addition, biochemical studies performed in extract from transgenic plants showed that RFP-TMCT is an integral membrane protein. Full-length RFP-TMCT was also found in the vacuolar lumen, suggesting internalization into destination vacuole. Not colocalization of RFP-TMCT with tonoplast and plasma membrane markers were observed. This membrane vacuolar determinant sorting signal could be used for future application in molecular pharming as an alternative means to sort proteins of interest to vacuoles.

  6. Looking inside phytoplasma-infected sieve elements: A combined microscopy approach using Arabidopsis thaliana as a model plant.

    PubMed

    Pagliari, Laura; Martini, Marta; Loschi, Alberto; Musetti, Rita

    2016-10-01

    Phytoplasmas are phloem-inhabiting plant pathogens that affect over one thousand plant species, representing a severe threat to agriculture. The absence of an effective curative strategy and the economic importance of many affected crops make a priority of studying how plants respond to phytoplasma infection. Nevertheless, the study of phytoplasmas has been hindered by the extreme difficulty of culturing them in vitro and by impediments to natural host plant surveys such as low phytoplasma titre, long plant life cycle and poor knowledge of natural host-plant biology. Stating correspondence between macroscopic symptoms of phytoplasma infected Arabidopsis thaliana and those observed in natural host plants, over the last decade some authors have started to use this plant as a model for studying phytoplasma-plant interactions. Nevertheless, the morphological and ultrastructural modifications occurring in A. thaliana tissues following phytoplasma infection have never been described in detail. In this work, we adopted a combined-microscopy approach to verify if A. thaliana can be considered a reliable model for the study of phytoplasma-plant interactions at the microscopical level. The consistent presence of phytoplasma in infected phloem allowed detailed study of the infection process and the relationship established by phytoplasmas with different components of the sieve elements. In infected A. thaliana, phytoplasmas induced strong disturbances of host plant development that were mainly due to phloem disorganization and impairment. Light microscopy showed collapse, necrosis and hyperplasia of phloem cells. TEM observations of sieve elements identified two common plant-responses to phytoplasma infection: phloem protein agglutination and callose deposition. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Gravitropism in Arabidopsis thaliana: Root-specific action of the EHB gene and violation of the resultant law.

    PubMed

    Dümmer, Michaela; Forreiter, Christoph; Galland, Paul

    2015-09-15

    Gravitropic bending of seedlings of Arabidopsis thaliana in response to centrifugal accelerations was determined in a range between 0.0025 and 4×g to revisit and validate the so-called resultant law, which claims that centrifugation causes gravitropic organs to orient parallel to the resultant stimulus vector. We show here for seedlings of A. thaliana that this empirical law holds for hypocotyls but surprisingly fails for roots. While the behavior of hypocotyls could be modeled by an arc tangent function predicted by the resultant law, roots displayed a sharp maximum at 1.8×g that substantially overshoots the predicted value and that represents a novel phenomenon, diagravitropism elicited by centrifugal acceleration. The gravitropic bending critically depended on the orientation of the seedling relative to the centrifugal acceleration. If the centrifugal vector pointed toward the cotyledons, gravitropic bending of hypocotyls and roots was substantially enhanced. The complex behavior of Arabidopsis seedlings provides strong evidence that gravitropic bending entails a cosine component (longitudinal stimulus) to which the seedlings were more sensitive than to the classical sine component. The absolute gravitropic thresholds of hypocotyls and roots were determined in a clinostat-centrifuge and found to be below 0.015×g. A tropism mutant lacking the EHB1 protein, which interacts with ARF-GAP (ARF GTPase-activating protein) and thus indirectly with a small ARF-type G protein, displayed a lower gravitropic threshold for roots and also enhanced bending, while the responses of the hypocotyls remained nearly unaffected. Copyright © 2015 Elsevier GmbH. All rights reserved.

  8. Towards systems biology of the gravity response of higher plants -multiscale analysis of Arabidopsis thaliana root growth

    NASA Astrophysics Data System (ADS)

    Palme, Klaus; Aubry, D.; Bensch, M.; Schmidt, T.; Ronneberger, O.; Neu, C.; Li, X.; Wang, H.; Santos, F.; Wang, B.; Paponov, I.; Ditengou, F. A.; Teale, W. T.; Volkmann, D.; Baluska, F.; Nonis, A.; Trevisan, S.; Ruperti, B.; Dovzhenko, A.

    Gravity plays a fundamental role in plant growth and development. Up to now, little is known about the molecular organisation of the signal transduction cascades and networks which co-ordinate gravity perception and response. By using an integrated systems biological approach, a systems analysis of gravity perception and the subsequent tightly-regulated growth response is planned in the model plant Arabidopsis thaliana. This approach will address questions such as: (i) what are the components of gravity signal transduction pathways? (ii) what are the dynamics of these components? (iii) what is their spatio-temporal regulation in different tis-sues? Using Arabidopsis thaliana as a model-we use root growth to obtain insights in the gravity response. New techniques enable identification of the individual genes affected by grav-ity and further integration of transcriptomics and proteomics data into interaction networks and cell communication events that operate during gravitropic curvature. Using systematic multiscale analysis we have identified regulatory networks consisting of transcription factors, the protein degradation machinery, vesicle trafficking and cellular signalling during the gravire-sponse. We developed approach allowing to incorporate key features of the root system across all relevant spatial and temporal scales to describe gene-expression patterns and correlate them with individual gene and protein functions. Combination of high-resolution microscopy and novel computational tools resulted in development of the root 3D model in which quantitative descriptions of cellular network properties and of multicellular interactions important in root growth and gravitropism can be integrated for the first time.

  9. Overexpression of ALDH10A8 and ALDH10A9 Genes Provides Insight into Their Role in Glycine Betaine Synthesis and Affects Primary Metabolism in Arabidopsis thaliana.

    PubMed

    Missihoun, Tagnon D; Willée, Eva; Guegan, Jean-Paul; Berardocco, Solenne; Shafiq, Muhammad R; Bouchereau, Alain; Bartels, Dorothea

    2015-09-01

    Betaine aldehyde dehydrogenases oxidize betaine aldehyde to glycine betaine in species that accumulate glycine betaine as a compatible solute under stress conditions. In contrast, the physiological function of betaine aldehyde dehydrogenase genes is at present unclear in species that do not accumulate glycine betaine, such as Arabidopsis thaliana. To address this question, we overexpressed the Arabidopsis ALDH10A8 and ALDH10A9 genes, which were identified to code for betaine aldehyde dehydrogenases, in wild-type A. thaliana. We analysed changes in metabolite contents of transgenic plants in comparison with the wild type. Using exogenous or endogenous choline, our results indicated that ALDH10A8 and ALDH10A9 are involved in the synthesis of glycine betaine in Arabidopsis. Choline availability seems to be a factor limiting glycine betaine synthesis. Moreover, the contents of diverse metabolites including sugars (glucose and fructose) and amino acids were altered in fully developed transgenic plants compared with the wild type. The plant metabolic response to salt and the salt stress tolerance were impaired only in young transgenic plants, which exhibited a delayed growth of the seedlings early after germination. Our results suggest that a balanced expression of the betaine aldehyde dehydrogenase genes is important for early growth of A. thaliana seedlings and for salt stress mitigation in young seedlings. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  10. GraPhoBox: Gravitropism and phototropism in Arabidopsis thaliana

    NASA Astrophysics Data System (ADS)

    Buizer, K.

    2007-09-01

    The morphology of plants is directed by the directional growth of roots and shoots. Gravity and light direction are the two major environmental stimuli important for directional growth. The 'GraPhoBox' experiment, flown on the Dutch DELTA mission to the ISS in April 2004, tries to elucidate the different effects of gravitropism and phototropism on plants, and their combined effects on plant morphology. Wild-type Arabidopsis thaliana (L.), phototropic-deficient mutants phot1 and gravitropic-deficient mutant pgm1 seeds were germinated in microgravity and in Earth gravity, in low light conditions and darkness. The angle of directional growth of roots and shoots was then assessed. Light is -even in the absense of gravity- the most important environmental cue for directional growth of shoots, while for roots gravity is by far the most important cue, and light is only a very minor factor due to their poor phototropic capacity. Compared to roots, shoots are deviated more than roots in microgravity and therefore less gravity-dependent. All results together suggests that environmental cues are differently percepted by roots and shoots which also adapt differently. Furthermore, environmental cues are probably transferred little or not to the opposite side of the plant.

  11. 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

  12. 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.

  13. Arabidopsis thaliana FANCD2 Promotes Meiotic Crossover Formation[OPEN

    PubMed Central

    Kurzbauer, Marie-Therese; Kerzendorfer, Claudia; Sims, Jason; Oliver, Cecilia; Mosiolek, Magdalena; Schweizer, Dieter

    2018-01-01

    Fanconi anemia (FA) is a human autosomal recessive disorder characterized by chromosomal instability, developmental pathologies, predisposition to cancer, and reduced fertility. So far, 19 genes have been implicated in FA, most of them involved in DNA repair. Some are conserved across higher eukaryotes, including plants. The Arabidopsis thaliana genome encodes a homolog of the Fanconi anemia D2 gene (FANCD2) whose function in DNA repair is not yet fully understood. Here, we provide evidence that AtFANCD2 is required for meiotic homologous recombination. Meiosis is a specialized cell division that ensures reduction of genomic content by half and DNA exchange between homologous chromosomes via crossovers (COs) prior to gamete formation. In plants, a mutation in AtFANCD2 results in a 14% reduction of CO numbers. Genetic analysis demonstrated that AtFANCD2 acts in parallel to both MUTS HOMOLOG4 (AtMSH4), known for its role in promoting interfering COs and MMS AND UV SENSITIVE81 (AtMUS81), known for its role in the formation of noninterfering COs. AtFANCD2 promotes noninterfering COs in a MUS81-independent manner and is therefore part of an uncharted meiotic CO-promoting mechanism, in addition to those described previously. PMID:29352063

  14. Heterologous expression of two GPATs from Jatropha curcas alters seed oil levels in transgenic Arabidopsis thaliana.

    PubMed

    Misra, Aparna; Khan, Kasim; Niranjan, Abhishek; Kumar, Vinod; Sane, Vidhu A

    2017-10-01

    Oils and fats are stored in endosperm during seed development in the form of triacylglycerols. Three acyltransferases: glycerol-3-phosphate acyltransferase (GPAT), lysophosphatidyl acyltransferase (LPAT) and diacylglycerol acyltransferase (DGAT) are involved in the storage lipid biosynthesis and catalyze the stepwise acylation of glycerol backbone. In this study two members of GPAT gene family (JcGPAT1 and JcGPAT2) from Jatropha seeds were identified and characterized. Sequence analysis suggested that JcGPAT1 and JcGPAT2 are homologous to Arabidopsis acyltransferase-1 (ATS1) and AtGPAT9 respectively. The sub-cellular localization studies of these two GPATs showed that JcGPAT1 localizes into plastid whereas JcGPAT2 localizes in to endoplasmic reticulum. JcGPAT1 and JcGPAT2 expressed throughout the seed development with higher expression in fully matured seed compared to immature seed. The transcript levels of JcGPAT2 were higher in comparison to JcGPAT1 in different developmental stages of seed. Over-expression of JcGPAT1 and JcGPAT2 under constitutive and seed specific promoters in Arabidopsis thaliana increased total oil content. Transgenic seeds of JcGPAT2-OE lines accumulated 43-60% more oil than control seeds whereas seeds of Arabidopsis lines over-expressing plastidial GPAT lead to only 13-20% increase in oil content. Functional characterization of GPAT homologues of Jatropha in Arabidopsis suggested that these are involved in oil biosynthesis but might have specific roles in Jatropha. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. A Trio of Viral Proteins Tunes Aphid-Plant Interactions in Arabidopsis thaliana

    PubMed Central

    Du, Zhiyou; Murphy, Alex M.; Anggoro, Damar Tri; Tungadi, Trisna; Luang-In, Vijitra; Lewsey, Mathew G.; Rossiter, John T.; Powell, Glen; Smith, Alison G.; Carr, John P.

    2013-01-01

    Background Virus-induced deterrence to aphid feeding is believed to promote plant virus transmission by encouraging migration of virus-bearing insects away from infected plants. We investigated the effects of infection by an aphid-transmitted virus, cucumber mosaic virus (CMV), on the interaction of Arabidopsis thaliana, one of the natural hosts for CMV, with Myzus persicae (common names: ‘peach-potato aphid’, ‘green peach aphid’). Methodology/Principal Findings Infection of Arabidopsis (ecotype Col-0) with CMV strain Fny (Fny-CMV) induced biosynthesis of the aphid feeding-deterrent 4-methoxy-indol-3-yl-methylglucosinolate (4MI3M). 4MI3M inhibited phloem ingestion by aphids and consequently discouraged aphid settling. The CMV 2b protein is a suppressor of antiviral RNA silencing, which has previously been implicated in altering plant-aphid interactions. Its presence in infected hosts enhances the accumulation of CMV and the other four viral proteins. Another viral gene product, the 2a protein (an RNA-dependent RNA polymerase), triggers defensive signaling, leading to increased 4MI3M accumulation. The 2b protein can inhibit ARGONAUTE1 (AGO1), a host factor that both positively-regulates 4MI3M biosynthesis and negatively-regulates accumulation of substance(s) toxic to aphids. However, the 1a replicase protein moderated 2b-mediated inhibition of AGO1, ensuring that aphids were deterred from feeding but not poisoned. The LS strain of CMV did not induce feeding deterrence in Arabidopsis ecotype Col-0. Conclusions/Significance Inhibition of AGO1 by the 2b protein could act as a booby trap since this will trigger antibiosis against aphids. However, for Fny-CMV the interplay of three viral proteins (1a, 2a and 2b) appears to balance the need of the virus to inhibit antiviral silencing, while inducing a mild resistance (antixenosis) that is thought to promote transmission. The strain-specific effects of CMV on Arabidopsis-aphid interactions, and differences between

  16. Connecting Source with Sink: The Role of Arabidopsis AAP8 in Phloem Loading of Amino Acids1[OPEN

    PubMed Central

    Santiago, James P.; Tegeder, Mechthild

    2016-01-01

    Allocation of large amounts of nitrogen to developing organs occurs in the phloem and is essential for plant growth and seed development. In Arabidopsis (Arabidopsis thaliana) and many other plant species, amino acids represent the dominant nitrogen transport forms in the phloem, and they are mainly synthesized in photosynthetically active source leaves. Following their synthesis, a broad spectrum of the amino nitrogen is actively loaded into the phloem of leaf minor veins and transported within the phloem sap to sinks such as developing leaves, fruits, or seeds. Controlled regulation of the source-to-sink transport of amino acids has long been postulated; however, the molecular mechanism of amino acid phloem loading was still unknown. In this study, Arabidopsis AMINO ACID PERMEASE8 (AAP8) was shown to be expressed in the source leaf phloem and localized to the plasma membrane, suggesting its function in phloem loading. This was further supported by transport studies with aap8 mutants fed with radiolabeled amino acids and by leaf exudate analyses. In addition, biochemical and molecular analyses revealed alterations in leaf nitrogen pools and metabolism dependent on the developmental stage of the mutants. Decreased amino acid phloem loading and partitioning to sinks led to decreased silique and seed numbers, but seed protein levels were unchanged, demonstrating the importance of AAP8 function for sink development rather than seed quality. Overall, these results show that AAP8 plays an important role in source-to-sink partitioning of nitrogen and that its function affects source leaf physiology and seed yield. PMID:27016446

  17. Structural insight into the binding interactions of modeled structure of Arabidopsis thaliana urease with urea: an in silico study.

    PubMed

    Yata, Vinod Kumar; Thapa, Arun; Mattaparthi, Venkata Satish Kumar

    2015-01-01

    Urease (EC 3.5.1.5., urea amidohydrolase) catalyzes the hydrolysis of urea to ammonia and carbon dioxide. Urease is present to a greater abundance in plants and plays significant role related to nitrogen recycling from urea. But little is known about the structure and function of the urease derived from the Arabidopsis thaliana, the model system of choice for research in plant biology. In this study, a three-dimensional structural model of A. thaliana urease was constructed using computer-aided molecular modeling technique. The characteristic structural features of the modeled structure were then studied using atomistic molecular dynamics simulation. It was observed that the modeled structure was stable and regions between residues index (50-80, 500-700) to be significantly flexible. From the docking studies, we detected the possible binding interactions of modeled urease with urea. Ala399, Ile675, Thr398, and Thr679 residues of A. thaliana urease were observed to be significantly involved in binding with the substrate urea. We also compared the docking studies of ureases from other sources such as Canavalia ensiformis, Helicobacter pylori, and Bacillus pasteurii. In addition, we carried out mutation analysis to find the highly mutable amino acid residues of modeled A. thaliana urease. In this particular study, we observed Met485, Tyr510, Ser786, Val426, and Lys765 to be highly mutable amino acids. These results are significant for the mutagenesis analysis. As a whole, this study expounds the salient structural features as well the binding interactions of the modeled structure of A. thaliana urease.

  18. Effective tolerance based on resource reallocation is a virus-specific defence in Arabidopsis thaliana.

    PubMed

    Shukla, Aayushi; Pagán, Israel; García-Arenal, Fernando

    2018-06-01

    Plant viruses often harm their hosts, which have developed mechanisms to prevent or minimize the effects of virus infection. Resistance and tolerance are the two main plant defences to pathogens. Although resistance to plant viruses has been studied extensively, tolerance has received much less attention. Theory predicts that tolerance to low-virulent parasites would be achieved through resource reallocation from growth to reproduction, whereas tolerance to high-virulent parasites would be attained through shortening of the pre-reproductive period. We have shown previously that the tolerance of Arabidopsis thaliana to Cucumber mosaic virus (CMV), a relatively low-virulent virus in this host, accords to these predictions. However, whether other viruses trigger the same response, and how A. thaliana copes with highly virulent virus infections remains unexplored. To address these questions, we challenged six A. thaliana wild genotypes with five viruses with different genomic structures, life histories and transmission modes. In these plants, we quantified virus multiplication, virulence, and the effects of infection on plant growth and reproduction, and on the developmental schedule. Our results indicate that virus multiplication varies according to the virus × host genotype interaction. Conversely, effective tolerance is observed only on CMV infection, and is associated with resource reallocation from growth to reproduction. Tolerance to the other viruses is observed only in specific host-virus combinations and, at odds with theoretical predictions, is linked to longer pre-reproductive periods. These findings only partially agree with theoretical predictions, and contribute to a better understanding of pathogenic processes in plant-virus interactions. © 2017 BSPP AND JOHN WILEY & SONS LTD.

  19. Quantitative monitoring of Arabidopsis thaliana growth and development using high-throughput plant phenotyping

    PubMed Central

    Arend, Daniel; Lange, Matthias; Pape, Jean-Michel; Weigelt-Fischer, Kathleen; Arana-Ceballos, Fernando; Mücke, Ingo; Klukas, Christian; Altmann, Thomas; Scholz, Uwe; Junker, Astrid

    2016-01-01

    With the implementation of novel automated, high throughput methods and facilities in the last years, plant phenomics has developed into a highly interdisciplinary research domain integrating biology, engineering and bioinformatics. Here we present a dataset of a non-invasive high throughput plant phenotyping experiment, which uses image- and image analysis- based approaches to monitor the growth and development of 484 Arabidopsis thaliana plants (thale cress). The result is a comprehensive dataset of images and extracted phenotypical features. Such datasets require detailed documentation, standardized description of experimental metadata as well as sustainable data storage and publication in order to ensure the reproducibility of experiments, data reuse and comparability among the scientific community. Therefore the here presented dataset has been annotated using the standardized ISA-Tab format and considering the recently published recommendations for the semantical description of plant phenotyping experiments. PMID:27529152

  20. Quantitative monitoring of Arabidopsis thaliana growth and development using high-throughput plant phenotyping.

    PubMed

    Arend, Daniel; Lange, Matthias; Pape, Jean-Michel; Weigelt-Fischer, Kathleen; Arana-Ceballos, Fernando; Mücke, Ingo; Klukas, Christian; Altmann, Thomas; Scholz, Uwe; Junker, Astrid

    2016-08-16

    With the implementation of novel automated, high throughput methods and facilities in the last years, plant phenomics has developed into a highly interdisciplinary research domain integrating biology, engineering and bioinformatics. Here we present a dataset of a non-invasive high throughput plant phenotyping experiment, which uses image- and image analysis- based approaches to monitor the growth and development of 484 Arabidopsis thaliana plants (thale cress). The result is a comprehensive dataset of images and extracted phenotypical features. Such datasets require detailed documentation, standardized description of experimental metadata as well as sustainable data storage and publication in order to ensure the reproducibility of experiments, data reuse and comparability among the scientific community. Therefore the here presented dataset has been annotated using the standardized ISA-Tab format and considering the recently published recommendations for the semantical description of plant phenotyping experiments.