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

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, Chri
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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1004.2473%
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...

Combined Transcript and Metabolite Profiling of Arabidopsis Grown under Widely Variant Growth Conditions Facilitates the Identification of Novel Metabolite-Mediated Regulation of Gene Expression[C][W]

Hannah, Matthew A.; Caldana, Camila; Steinhauser, Dirk; Balbo, Ilse; Fernie, Alisdair R.; Willmitzer, Lothar
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
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1014.4961%
Regulation of metabolism at the level of transcription and its corollary metabolite-mediated regulation of transcription are well-documented mechanisms by which plants adapt to circumstance. That said the function of only a minority of transcription factor networks are fully understood and it seems likely that we have only identified a subset of the metabolites that play a mediator function in the regulation of transcription. Here we describe an integrated genomics approach in which we perform combined transcript and metabolite profiling on Arabidopsis (Arabidopsis thaliana) plants challenged by various environmental extremes. We chose this approach to generate a large variance in the levels of all parameters recorded. The data was then statistically evaluated to identify metabolites whose level robustly correlated with those of a particularly large number of transcripts. Since correlation alone provides no proof of causality we subsequently attempted to validate these putative mediators of gene expression via a combination of statistical analysis of data available in publicly available databases and iterative experimental evaluation. Data presented here suggest that, on adoption of appropriate caution, the approach can be used for the identification of metabolite mediators of gene expression. As an exemplary case study we document that in plants...

Identification of Arabidopsis Mutants Impaired in the Systemic Regulation of Root Nitrate Uptake by the Nitrogen Status of the Plant1[C][W]

Girin, Thomas; El-Kafafi, El-Sayed; Widiez, Thomas; Erban, Alexander; Hubberten, Hans-Michael; Kopka, Joachim; Hoefgen, Rainer; Gojon, Alain; Lepetit, Marc
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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1007.116%
Nitrate uptake by the roots is under systemic feedback repression by high nitrogen (N) status of the whole plant. The NRT2.1 gene, which encodes a NO3− transporter involved in high-affinity root uptake, is a major target of this N signaling mechanism. Using transgenic Arabidopsis (Arabidopsis thaliana) plants expressing the pNRT2.1::LUC reporter gene (NL line), we performed a genetic screen to isolate mutants altered in the NRT2.1 response to high N provision. Three hni (for high nitrogen insensitive) mutants belonging to three genetic loci and related to single and recessive mutations were selected. Compared to NL plants, these mutants display reduced down-regulation of both NRT2.1 expression and high-affinity NO3− influx under repressive conditions. Split-root experiments demonstrated that this is associated with an almost complete suppression of systemic repression of pNRT2.1 activity by high N status of the whole plant. Other mechanisms related to N and carbon nutrition regulating NRT2.1 or involved in the control of root SO4− uptake by the plant sulfur status are not or are slightly affected. The hni mutations did not lead to significant changes in total N and NO3− contents of the tissues, indicating that hni mutants are more likely regulatory mutants rather than assimilatory mutants. Nevertheless...

Kiwifruit EIL and ERF Genes Involved in Regulating Fruit Ripening1[W]

Yin, Xue-ren; Allan, Andrew C.; Chen, Kun-song; Ferguson, Ian B.
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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1004.5212%
Kiwifruit (Actinidia deliciosa) is a climacteric fruit sensitive to low concentrations of ethylene. To investigate the transcriptional mechanisms underlying kiwifruit ethylene response, transcription factors encoding four EIN3-Like (EILs) and 14 Ethylene Response Factors (ERFs) were cloned from kiwifruit. Expression of these transcription factors was examined during fruit development. The expression of transcripts of most AdERFs was higher during early fruit development, with the exception of AdERF3, which increased with maturity. Several AdERFs were apparently down-regulated by ethylene, as they were affected by the ethylene inhibitor 1-methylcyclopropene and by antisense suppression of ACO (for 1-aminocyclopropane-1-carboxylic acid oxidase) in the fruit. In contrast, AdEILs were constitutively expressed during fruit development and ripening. The transcription factors AdEIL2 and AdEIL3 activated transcription of the ripening-related genes AdACO1 and AdXET5 (xyloglucan endotransglycosylase gene) and, when overexpressed in Arabidopsis (Arabidopsis thaliana), stimulated ethylene production. The potential repressor AdERF9 suppressed this promoter activity. These results support a role for kiwifruit EILs and ERFs in transcriptional regulation of ripening-related genes and in the regulation of kiwifruit fruit-ripening processes.

G-Box Binding Factor1 Reduces CATALASE2 Expression and Regulates the Onset of Leaf Senescence in Arabidopsis1[W][OA]

Smykowski, Anja; Zimmermann, Petra; Zentgraf, Ulrike
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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1009.85%
Hydrogen peroxide (H2O2) is discussed as being a signaling molecule in Arabidopsis (Arabidopsis thaliana) leaf senescence. Intracellular H2O2 levels are controlled by the H2O2-scavenging enzyme catalase in concert with other scavenging and producing systems. Catalases are encoded by a small gene family, and the expression of all three Arabidopsis catalase genes is regulated in a senescence-associated manner. CATALASE2 (CAT2) expression is down-regulated during bolting time at the onset of leaf senescence and appears to be involved in the elevation of the H2O2 level at this time point. To understand the role of CAT2 in senescence regulation in more detail, we used CAT2 promoter fragments in a yeast one-hybrid screen to isolate upstream regulatory factors. Among others, we could identify G-Box Binding Factor1 (GBF1) as a DNA-binding protein of the CAT2 promoter. Transient overexpression of GBF1 together with a CAT2:β-glucuronidase construct in tobacco (Nicotiana benthamiana) plants and Arabidopsis protoplasts revealed a negative effect of GBF1 on CAT2 expression. In gbf1 mutant plants, the CAT2 decrease in expression and activity at bolting time and the increase in H2O2 could no longer be observed. Consequently, the onset of leaf senescence and the expression of senescence-associated genes were delayed in gbf1 plants...

Distinct Gene Expression Profiles in Egg and Synergid Cells of Rice as Revealed by Cell Type-Specific Microarrays1[W][OA]

Ohnishi, Takayuki; Takanashi, Hideki; Mogi, Mirai; Takahashi, Hirokazu; Kikuchi, Shunsuke; Yano, Kentaro; Okamoto, Takashi; Fujita, Masahiro; Kurata, Nori; Tsutsumi, Nobuhiro
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
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1003.7982%
Double fertilization in flowering plants refers to a process in which two sperm cells, carried by the pollen tube, fertilize both the egg and the central cell after their release into a synergid cell of the female gametophyte. The molecular processes by which the female gametophytic cells express their unique functions during fertilization are not well understood. Genes expressed in egg and synergid cells might be important for multiple stages of the plant reproductive process. Here, we profiled genome-wide gene expression in egg and synergid cells in rice (Oryza sativa), a model monocot, using a nonenzymatic cell isolation technique. We found that the expression profiles of the egg and synergid cells were already specified at the micropylar end of the female gametophyte during the short developmental period that comprises the three consecutive mitotic nuclear divisions after megaspore generation. In addition, we identified a large number of genes expressed in the rice egg and synergid cells and characterized these genes using Gene Ontology analysis. The analysis suggested that epigenetic and posttranscriptional regulatory mechanisms are involved in the specification and/or maintenance of these cells. Comparisons between the rice profiles and reported Arabidopsis (Arabidopsis thaliana) profiles revealed that genes enriched in the egg/synergid cell of rice were distinct from those in Arabidopsis.

Leaf Rolling Controlled by the Homeodomain Leucine Zipper Class IV Gene Roc5 in Rice1[W]

Zou, Liang-ping; Sun, Xue-hui; Zhang, Zhi-guo; Liu, Peng; Wu, Jin-xia; Tian, Cai-juan; Qiu, Jin-long; Lu, Tie-gang
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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1004.7967%
Leaf rolling is considered an important agronomic trait in rice (Oryza sativa) breeding. To understand the molecular mechanism controlling leaf rolling, we screened a rice T-DNA insertion population and isolated the outcurved leaf1 (oul1) mutant showing abaxial leaf rolling. The phenotypes were caused by knockout of Rice outermost cell-specific gene5 (Roc5), an ortholog of the Arabidopsis (Arabidopsis thaliana) homeodomain leucine zipper class IV gene GLABRA2. Interestingly, overexpression of Roc5 led to adaxially rolled leaves, whereas cosuppression of Roc5 resulted in abaxial leaf rolling. Bulliform cell number and size increased in oul1 and Roc5 cosuppression plants but were reduced in Roc5-overexpressing lines. The data indicate that Roc5 negatively regulates bulliform cell fate and development. Gene expression profiling, quantitative polymerase chain reaction, and RNA interference (RNAi) analyses revealed that Protodermal Factor Like (PFL) was probably down-regulated in oul1. The mRNA level of PFL was increased in Roc5-overexpressing lines, and PFL-RNAi transgenic plants exhibit reversely rolling leaves by reason of increases of bulliform cell number and size, indicating that Roc5 may have a conserved function. These are, to our knowledge...

Structure and Expression Profile of the Phosphate Pht1 Transporter Gene Family in Mycorrhizal Populus trichocarpa1[W]

Loth-Pereda, Verónica; Orsini, Elena; Courty, Pierre-Emmanuel; Lota, Frédéric; Kohler, Annegret; Diss, Loic; Blaudez, Damien; Chalot, Michel; Nehls, Uwe; Bucher, Marcel; Martin, Francis
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
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1011.3189%
Gene networks involved in inorganic phosphate (Pi) acquisition and homeostasis in woody perennial species able to form mycorrhizal symbioses are poorly known. Here, we describe the features of the 12 genes coding for Pi transporters of the Pht1 family in poplar (Populus trichocarpa). Individual Pht1 transporters play distinct roles in acquiring and translocating Pi in different tissues of mycorrhizal and nonmycorrhizal poplar during different growth conditions and developmental stages. Pi starvation triggered the up-regulation of most members of the Pht1 family, especially PtPT9 and PtPT11. PtPT9 and PtPT12 showed a striking up-regulation in ectomycorrhizas and endomycorrhizas, whereas PtPT1 and PtPT11 were strongly down-regulated. PtPT10 transcripts were highly abundant in arbuscular mycorrhiza (AM) roots only. PtPT8 and PtPT10 are phylogenetically associated to the AM-inducible Pht1 subfamily I. The analysis of promoter sequences revealed conserved motifs similar to other AM-inducible orthologs in PtPT10 only. To gain more insight into gene regulatory mechanisms governing the AM symbiosis in woody plant species, the activation of the poplar PtPT10 promoter was investigated and detected in AM of potato (Solanum tuberosum) roots. These results indicated that the regulation of AM-inducible Pi transporter genes is conserved between perennial woody and herbaceous plant species. Moreover...

Intracompartmental and Intercompartmental Transcriptional Networks Coordinate the Expression of Genes for Organellar Functions1[W]

Leister, Dario; Wang, Xi; Haberer, Georg; Mayer, Klaus F.X.; Kleine, Tatjana
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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1006.96445%
Genes for mitochondrial and chloroplast proteins are distributed between the nuclear and organellar genomes. Organelle biogenesis and metabolism, therefore, require appropriate coordination of gene expression in the different compartments to ensure efficient synthesis of essential multiprotein complexes of mixed genetic origin. Whereas organelle-to-nucleus signaling influences nuclear gene expression at the transcriptional level, organellar gene expression (OGE) is thought to be primarily regulated posttranscriptionally. Here, we show that intracompartmental and intercompartmental transcriptional networks coordinate the expression of genes for organellar functions. Nearly 1,300 ATH1 microarray-based transcriptional profiles of nuclear and organellar genes for mitochondrial and chloroplast proteins in the model plant Arabidopsis (Arabidopsis thaliana) were analyzed. The activity of genes involved in organellar energy production (OEP) or OGE in each of the organelles and in the nucleus is highly coordinated. Intracompartmental networks that link the OEP and OGE gene sets serve to synchronize the expression of nucleus- and organelle-encoded proteins. At a higher regulatory level, coexpression of organellar and nuclear OEP/OGE genes typically modulates chloroplast functions but affects mitochondria only when chloroplast functions are perturbed. Under conditions that induce energy shortage...

Dynamic Alternations in Cellular and Molecular Components during Blossom-End Rot Development in Tomatoes Expressing sCAX1, a Constitutively Active Ca2+/H+ Antiporter from Arabidopsis1[W][OA]

Tonetto de Freitas, Sergio; Padda, Malkeet; Wu, Qingyu; Park, Sunghun; Mitcham, Elizabeth J.
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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1011.5294%
Although calcium (Ca) concentration in cellular compartments has been suggested to be tightly regulated, Ca deficiency disorders such as blossom-end rot (BER) in tomato (Solanum lycopersicum) fruit may be induced by abnormal regulation of Ca partitioning and distribution in the cell. The objectives of this work were to analyze the effects of high expression of the constitutively functional Arabidopsis (Arabidopsis thaliana) Ca2+/H+ exchanger (sCAX1) tonoplast protein in tomato fruit on cellular Ca partitioning and distribution, membrane integrity, and the transcriptional profile of genes potentially involved in BER development. Wild-type and sCAX1-expressing tomato plants were grown in a greenhouse. Wild-type plants did not develop BER, whereas sCAX1-expressing plants reached 100% BER incidence at 15 d after pollination. The sCAX1-expressing fruit pericarp had higher total tissue and water-soluble Ca concentrations, lower apoplastic and cytosolic Ca concentrations, higher membrane leakage, and Ca accumulation in the vacuole of sCAX1-expressing cells. Microarray analysis of healthy sCAX1-expressing fruit tissue indicated down-regulation of genes potentially involved in BER development, such as genes involved in membrane structure and repair and cytoskeleton metabolism...

An AP2 Domain-Containing Gene, ESE1, Targeted by the Ethylene Signaling Component EIN3 Is Important for the Salt Response in Arabidopsis1[W][OA]

Zhang, Lixia; Li, Zhuofu; Quan, Ruidang; Li, Guojing; Wang, Ruigang; Huang, Rongfeng
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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1012.1065%
Accumulating investigations reveal that ethylene signaling is involved in the salt response in Arabidopsis (Arabidopsis thaliana), and it has been reported that overexpression of a number of ethylene response factor (ERF) genes enhances salt tolerance; however, transcriptional regulation of the ethylene signal component ETHYLENE INSENSITIVE3 (EIN3) in the salt response has not been clearly defined. Consulting microarray data and transcriptional confirmations showed that three of the ERF genes were ethylene and salt inducible, named ESE1 to ESE3. Additionally, the expression of one of the ESE genes (ESE1) was suppressed in ein2, ein3-1, eil1-3, and ein3 eil1 but enhanced in EIN3-overexpressing (EIN3ox) lines. Inhibitors of ethylene biosynthesis, aminoethoxyvinylglycine, and ethylene action, AgNO3, reduced the expression of ESE1, while ethylene overproduction eto mutants enhanced the expression of ESE1, indicating that ESE1 is an ethylene-modulated gene downstream of EIN3/EIL1. Further analyses with biochemical and molecular approaches revealed that EIN3 physically binds to the ESE1 promoter, demonstrating that ESE1 was one target of EIN3. ESE1 in turn binds to promoters of salt-related genes, such as RD29A and COR15A. Moreover, either EIN3ox or ESE1ox was sufficient to enhance transcript levels of salt-related genes and salt tolerance. In addition...

MACROCALYX and JOINTLESS Interact in the Transcriptional Regulation of Tomato Fruit Abscission Zone Development1[C][W]

Nakano, Toshitsugu; Kimbara, Junji; Fujisawa, Masaki; Kitagawa, Mamiko; Ihashi, Nao; Maeda, Hideo; Kasumi, Takafumi; Ito, Yasuhiro
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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1006.5203%
Abscission in plants is a crucial process used to shed organs such as leaves, flowers, and fruits when they are senescent, damaged, or mature. Abscission occurs at predetermined positions called abscission zones (AZs). Although the regulation of fruit abscission is essential for agriculture, the developmental mechanisms remain unclear. Here, we describe a novel transcription factor regulating the development of tomato (Solanum lycopersicum) pedicel AZs. We found that the development of tomato pedicel AZs requires the gene MACROCALYX (MC), which was previously identified as a sepal size regulator and encodes a MADS-box transcription factor. MC has significant sequence similarity to Arabidopsis (Arabidopsis thaliana) FRUITFULL, which is involved in the regulation of fruit dehiscent zone development. The MC protein interacted physically with another MADS-box protein, JOINTLESS, which is known as a regulator of fruit abscission; the resulting heterodimer acquired a specific DNA-binding activity. Transcriptome analyses of pedicels at the preabscission stage revealed that the expression of the genes involved in phytohormone-related functions, cell wall modifications, fatty acid metabolism, and transcription factors is regulated by MC and JOINTLESS. The regulated genes include homologs of Arabidopsis WUSCHEL...

Light-Dependent Regulation of DEL1 Is Determined by the Antagonistic Action of E2Fb and E2Fc1[W][OA]

Berckmans, Barbara; Lammens, Tim; Van Den Daele, Hilde; Magyar, Zoltan; Bögre, Laszlo; De Veylder, Lieven
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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1005.6021%
Endoreduplication represents a variation on the cell cycle in which multiple rounds of DNA replication occur without subsequent chromosome separation and cytokinesis, thereby increasing the cellular DNA content. It is known that the DNA ploidy level of cells is controlled by external stimuli such as light; however, limited knowledge is available on how environmental signals regulate the endoreduplication cycle at the molecular level. Previously, we had demonstrated that the conversion from a mitotic cell cycle into an endoreduplication cycle is controlled by the atypical E2F transcription factor, DP-E2F-LIKE1 (DEL1), that represses the endocycle onset. Here, the Arabidopsis (Arabidopsis thaliana) DEL1 gene was identified as a transcriptional target of the classical E2Fb and E2Fc transcription factors that antagonistically control its transcript levels through competition for a single E2F cis-acting binding site. In accordance with the reported opposite effects of light on the protein levels of E2Fb and E2Fc, DEL1 transcription depended on the light regime. Strikingly, modified DEL1 expression levels uncoupled the link between light and endoreduplication in hypocotyls, implying that DEL1 acts as a regulatory connection between endocycle control and the photomorphogenic response.

From Model to Crop: Functional Analysis of a STAY-GREEN Gene in the Model Legume Medicago truncatula and Effective Use of the Gene for Alfalfa Improvement1[W][OA]

Zhou, Chuanen; Han, Lu; Pislariu, Catalina; Nakashima, Jin; Fu, Chunxiang; Jiang, Qingzhen; Quan, Li; Blancaflor, Elison B.; Tang, Yuhong; Bouton, Joseph H.; Udvardi, Michael; Xia, Guangmin; Wang, Zeng-Yu
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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1004.8643%
Medicago truncatula has been developed into a model legume. Its close relative alfalfa (Medicago sativa) is the most widely grown forage legume crop in the United States. By screening a large population of M. truncatula mutants tagged with the transposable element of tobacco (Nicotiana tabacum) cell type1 (Tnt1), we identified a mutant line (NF2089) that maintained green leaves and showed green anthers, central carpels, mature pods, and seeds during senescence. Genetic and molecular analyses revealed that the mutation was caused by Tnt1 insertion in a STAY-GREEN (MtSGR) gene. Transcript profiling analysis of the mutant showed that loss of the MtSGR function affected the expression of a large number of genes involved in different biological processes. Further analyses revealed that SGR is implicated in nodule development and senescence. MtSGR expression was detected across all nodule developmental zones and was higher in the senescence zone. The number of young nodules on the mutant roots was higher than in the wild type. Expression levels of several nodule senescence markers were reduced in the sgr mutant. Based on the MtSGR sequence, an alfalfa SGR gene (MsSGR) was cloned, and transgenic alfalfa lines were produced by RNA interference. Silencing of MsSGR led to the production of stay-green transgenic alfalfa. This beneficial trait offers the opportunity to produce premium alfalfa hay with a more greenish appearance. In addition...

Regulation of High-Affinity Nitrate Uptake in Roots of Arabidopsis Depends Predominantly on Posttranscriptional Control of the NRT2.1/NAR2.1 Transport System1[W][OA]

Laugier, Edith; Bouguyon, Eléonore; Mauriès, Adeline; Tillard, Pascal; Gojon, Alain; Lejay, Laurence
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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1010.3958%
In Arabidopsis (Arabidopsis thaliana), the NRT2.1 gene codes for the main component of the root nitrate (NO3−) high-affinity transport system (HATS). Due to the strong correlation generally found between high-affinity root NO3− influx and NRT2.1 mRNA level, it has been postulated that transcriptional regulation of NRT2.1 is a key mechanism for modulation of the HATS activity. However, this hypothesis has never been demonstrated, and is challenged by studies suggesting the occurrence of posttranscriptional regulation at the NRT2.1 protein level. To unambiguously clarify the respective roles of transcriptional and posttranscriptional regulations of NRT2.1, we generated transgenic lines expressing a functional 35S::NRT2.1 transgene in an atnrt2.1 mutant background. Despite a high and constitutive NRT2.1 transcript accumulation in the roots, the HATS activity was still down-regulated in the 35S::NRT2.1 transformants in response to repressive nitrogen or dark treatments that strongly reduce NRT2.1 transcription and NO3− HATS activity in the wild type. In some treatments, this was associated with a decline of NRT2.1 protein abundance, indicating posttranscriptional regulation of NRT2.1. However, in other instances, NRT2.1 protein level remained constant. Changes in abundance of NAR2.1...

Expression of the R2R3-MYB Transcription Factor TaMYB14 from Trifolium arvense Activates Proanthocyanidin Biosynthesis in the Legumes Trifolium repens and Medicago sativa1[W][OA]

Hancock, Kerry R.; Collette, Vern; Fraser, Karl; Greig, Margaret; Xue, Hong; Richardson, Kim; Jones, Chris; Rasmussen, Susanne
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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1005.8125%
Proanthocyanidins (PAs) are oligomeric flavonoids and one group of end products of the phenylpropanoid pathway. PAs have been reported to be beneficial for human and animal health and are particularly important in pastoral agricultural systems for improved animal production and reduced greenhouse gas emissions. However, the main forage legumes grown in these systems, such as Trifolium repens and Medicago sativa, do not contain any substantial amounts of PAs in leaves. We have identified from the foliar PA-accumulating legume Trifolium arvense an R2R3-MYB transcription factor, TaMYB14, and provide evidence that this transcription factor is involved in the regulation of PA biosynthesis in legumes. TaMYB14 expression is necessary and sufficient to up-regulate late steps of the phenylpropanoid pathway and to induce PA biosynthesis. RNA interference silencing of TaMYB14 resulted in almost complete cessation of PA biosynthesis in T. arvense, whereas Nicotiana tabacum, M. sativa, and T. repens plants constitutively expressing TaMYB14 synthesized and accumulated PAs in leaves up to 1.8% dry matter. Targeted liquid chromatography-multistage tandem mass spectrometry analysis identified foliar PAs up to degree of polymerization 6 in leaf extracts. Hence...

Differential Expression of the Chlamydomonas [FeFe]-Hydrogenase-Encoding HYDA1 Gene Is Regulated by the COPPER RESPONSE REGULATOR11[C][W]

Pape, Miriam; Lambertz, Camilla; Happe, Thomas; Hemschemeier, Anja
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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1012.4699%
The unicellular green alga Chlamydomonas reinhardtii adapts to anaerobic or hypoxic conditions by developing a complex fermentative metabolism including the production of molecular hydrogen by [FeFe]-hydrogenase isoform1 (HYDA1). HYDA1 transcript and hydrogenase protein accumulate in the absence of oxygen or copper (Cu). Factors regulating this differential gene expression have been unknown so far. In this study, we report on the isolation of a Chlamydomonas mutant strain impaired in HYDA1 gene expression by screening an insertional mutagenesis library for HYDA1 promoter activity using the arylsulfatase-encoding ARYLSULFATASE2 gene as a selection marker. The mutant strain has a deletion of the COPPER RESPONSE REGULATOR1 (CRR1) gene encoding for CRR1, indicating that this SQUAMOSA-PROMOTER BINDING PROTEIN (SBP) domain transcription factor is involved in the regulation of HYDA1 transcription. Treating the C. reinhardtii wild type with mercuric ions, which were shown to inhibit the binding of the SBP domain to DNA, prevented or deactivated HYDA1 gene expression. Reporter gene analyses of the HYDA1 promoter revealed that two GTAC motifs, which are known to be the cores of CRR1 binding sites, are necessary for full promoter activity in hypoxic conditions or upon Cu starvation. However...

MEDIATOR25 Acts as an Integrative Hub for the Regulation of Jasmonate-Responsive Gene Expression in Arabidopsis1[C][W]

Çevik, Volkan; Kidd, Brendan N.; Zhang, Peijun; Hill, Claire; Kiddle, Steve; Denby, Katherine J.; Holub, Eric B.; Cahill, David M.; Manners, John M.; Schenk, Peer M.; Beynon, Jim; Kazan, Kemal
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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1010.7446%
The PHYTOCHROME AND FLOWERING TIME1 gene encoding the MEDIATOR25 (MED25) subunit of the eukaryotic Mediator complex is a positive regulator of jasmonate (JA)-responsive gene expression in Arabidopsis (Arabidopsis thaliana). Based on the function of the Mediator complex as a bridge between DNA-bound transcriptional activators and the RNA polymerase II complex, MED25 has been hypothesized to function in association with transcriptional regulators of the JA pathway. However, it is currently not known mechanistically how MED25 functions to regulate JA-responsive gene expression. In this study, we show that MED25 physically interacts with several key transcriptional regulators of the JA signaling pathway, including the APETALA2 (AP2)/ETHYLENE RESPONSE FACTOR (ERF) transcription factors OCTADECANOID-RESPONSIVE ARABIDOPSIS AP2/ERF59 and ERF1 as well as the master regulator MYC2. Physical interaction detected between MED25 and four group IX AP2/ERF transcription factors was shown to require the activator interaction domain of MED25 as well as the recently discovered Conserved Motif IX-1/EDLL transcription activation motif of MED25-interacting AP2/ERFs. Using transcriptional activation experiments, we also show that OCTADECANOID-RESPONSIVE ARABIDOPSIS AP2/ERF59- and ERF1-dependent activation of PLANT DEFENSIN1.2 as well as MYC2-dependent activation of VEGETATIVE STORAGE PROTEIN1 requires a functional MED25. In addition...

Positive Regulation of psbA Gene Expression by cis-Encoded Antisense RNAs in Synechocystis sp. PCC 68031[OA]

Sakurai, Isamu; Stazic, Damir; Eisenhut, Marion; Vuorio, Eerika; Steglich, Claudia; Hess, Wolfgang R.; Aro, Eva-Mari
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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The D1 protein of photosystem II in the thylakoid membrane of photosynthetic organisms is encoded by psbA genes, which in cyanobacteria occur in the form of a small gene family. Light-dependent up-regulation of psbA gene expression is crucial to ensure the proper replacement of the D1 protein. To gain a high level of gene expression, psbA transcription can be enhanced by several orders of magnitude. Recent transcriptome analyses demonstrated a high number of cis-encoded antisense RNAs (asRNAs) in bacteria, but very little is known about their possible functions. Here, we show the presence of two cis-encoded asRNAs (PsbA2R and PsbA3R) of psbA2 and psbA3 from Synechocystis sp. PCC 6803. These asRNAs are located in the 5′ untranslated region of psbA2 and psbA3 genes. Their expression becomes up-regulated by light and down-regulated by darkness, similar to their target mRNAs. In the PsbA2R-suppressing strain [PsbA2R(−)], the amount of psbA2 mRNA was only about 50% compared with the control strain. Likewise, we identified a 15% lowered activity of photosystem II and a reduced amount of the D1 protein in PsbA2R(−) compared with the control strain. The function of PsbA2R in the stabilization of psbA2 mRNA was shown from in vitro RNase E assay when the AU box and the ribosome-binding site in the 5′ untranslated region of psbA2 mRNA were both covered by PsbA2R. These results add another layer of complexity to the mechanisms that contribute to psbA gene expression and show PsbA2R as a positively acting factor to achieve a maximum level of D1 synthesis.

The Effect of TRANSPARENT TESTA2 on Seed Fatty Acid Biosynthesis and Tolerance to Environmental Stresses during Young Seedling Establishment in Arabidopsis1[W][OA]

Chen, Mingxun; Wang, Zhong; Zhu, Yana; Li, Zhilan; Hussain, Nazim; Xuan, Lijie; Guo, Wanli; Zhang, Guoping; Jiang, Lixi
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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In plants, fatty acids (FAs) and FA-derived complex lipids are major carbon and energy reserves in seeds. They are essential components of cellular membranes and cellular signal or hormone molecules. Although TRANSPARENT TESTA2 (TT2) is well studied for its function in regulating proanthocyanidin biosynthesis in the seed coat, little attention has been given to its role in affecting seed FA accumulation and tolerance to environmental stresses. We demonstrate that the tt2 mutation remarkably increased the seed FA content, decreased seed weight, and altered the FA composition. The increase in FA content in the tt2 seeds was due to the relative decrease of seed coat proportion as well as the more efficient FA synthesis in the tt2 embryo. Microarray analysis revealed that tt2 mutation up-regulated a group of genes critical to FA biosynthesis and embryonic development. The mutation also altered the gene expressions that respond to stress. The microarray analysis discovered that the increase in FA accumulation of the tt2 seeds were accompanied by the significant up-regulation of FUSCA3, a transcriptional factor for embryonic development and FATTY ACID ELONGASE1, which catalyzes the elongation of FA chains. Moreover, lower seed protein accumulation during seed maturation also contributed to the increased seed FA accumulation in tt2 mutants. This study advances the understanding of the TT2 gene in seed FA accumulation and abiotic stresses during seed germination and seedling establishment.