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1.
Plant Physiol ; 180(2): 1066-1080, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30886115

RESUMO

Improving the water use efficiency (WUE) of crop plants without trade-offs in growth and yield is considered a utopic goal. However, recent studies on model plants show that partial restriction of transpiration can occur without a reduction in CO2 uptake and photosynthesis. In this study, we analyzed the potentials and constraints of improving WUE in Arabidopsis (Arabidopsis thaliana) and in wheat (Triticum aestivum). We show that the analyzed Arabidopsis wild-type plants consume more water than is required for unrestricted growth. WUE was enhanced without a growth penalty by modulating abscisic acid (ABA) responses either by using overexpression of specific ABA receptors or deficiency of ABA coreceptors. Hence, the plants showed higher water productivity compared with the wild-type plants; that is, equal growth with less water. The high WUE trait was resilient to changes in light intensity and water availability, but it was sensitive to the ambient temperature. ABA application to plants generated a partial phenocopy of the water-productivity trait. ABA application, however, was never as effective as genetic modification in enhancing water productivity, probably because ABA indiscriminately targets all ABA receptors. ABA agonists selective for individual ABA receptors might offer an approach to phenocopy the water-productivity trait of the high WUE lines. ABA application to wheat grown under near-field conditions improved WUE without detectable growth trade-offs. Wheat yields are heavily impacted by water deficit, and our identification of this crop as a promising target for WUE improvement may help contribute to greater food security.


Assuntos
Ácido Abscísico/metabolismo , Arabidopsis/fisiologia , Proteínas de Plantas/metabolismo , Receptores de Superfície Celular/metabolismo , Triticum/fisiologia , Água/metabolismo , Ácido Abscísico/farmacologia , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Ecótipo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Transpiração Vegetal/efeitos dos fármacos , Plantas Geneticamente Modificadas , Temperatura , Triticum/efeitos dos fármacos
2.
Bioorg Med Chem ; 27(24): 115142, 2019 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-31685332

RESUMO

Novel synthetic lead structures interacting with RCAR/(PYR/PYL) receptor proteins were identified based on the results of a high-throughput screening campaign of a large compound library followed by focused SAR studies of the three most promising hit clusters. Whilst indolinylmethyl sulfonamides 8y,z and phenylsulfonyl ethylenediamines 9y,z showed strong affinities for RCAR/ (PYR/PYL) receptor proteins in wheat, thiotriazolyl acetamides 7f,s exhibited promising efficacy against drought stress in vivo (wheat, corn and canola) combined with confirmed target interaction in wheat and arabidopsis thaliana. Remarkably, binding affinities of several representatives of 8 and 9 were on the same level or even better than the essential plant hormone abscisic acid (ABA).


Assuntos
Ácido Abscísico/análogos & derivados , Reguladores de Crescimento de Plantas/química , Reguladores de Crescimento de Plantas/farmacologia , Proteínas de Plantas/química , Ácido Abscísico/química , Ácido Abscísico/farmacologia , Produtos Agrícolas , Secas , Descoberta de Drogas , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Ensaios de Triagem em Larga Escala , Estrutura Molecular , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Ligação Proteica , Sulfonamidas , Triticum/genética , Triticum/metabolismo
3.
Proc Natl Acad Sci U S A ; 106(25): 10348-53, 2009 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-19506259

RESUMO

Rising demand for food and bioenergy makes it imperative to breed for increased crop yield. Vegetative plant growth could be driven by resource acquisition or developmental programs. Metabolite profiling in 94 Arabidopsis accessions revealed that biomass correlates negatively with many metabolites, especially starch. Starch accumulates in the light and is degraded at night to provide a sustained supply of carbon for growth. Multivariate analysis revealed that starch is an integrator of the overall metabolic response. We hypothesized that this reflects variation in a regulatory network that balances growth with the carbon supply. Transcript profiling in 21 accessions revealed coordinated changes of transcripts of more than 70 carbon-regulated genes and identified 2 genes (myo-inositol-1-phosphate synthase, a Kelch-domain protein) whose transcripts correlate with biomass. The impact of allelic variation at these 2 loci was shown by association mapping, identifying them as candidate lead genes with the potential to increase biomass production.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Metabolismo Energético/genética , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Redes Reguladoras de Genes , Amido/metabolismo , Alelos , Arabidopsis/genética , Arabidopsis/metabolismo , Sequência de Bases , Metabolismo dos Carboidratos/genética , Mapeamento Cromossômico , Perfilação da Expressão Gênica , Variação Genética , Análise dos Mínimos Quadrados , Dados de Sequência Molecular
4.
Plant J ; 56(2): 181-195, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18564380

RESUMO

The fungal pathogen Ustilago maydis establishes a biotrophic relationship with its host plant maize (Zea mays). Hallmarks of the disease are large plant tumours in which fungal proliferation occurs. Previous studies suggested that classical defence pathways are not activated. Confocal microscopy, global expression profiling and metabolic profiling now shows that U. maydis is recognized early and triggers defence responses. Many of these early response genes are downregulated at later time points, whereas several genes associated with suppression of cell death are induced. The interplay between fungus and host involves changes in hormone signalling, induction of antioxidant and secondary metabolism, as well as the prevention of source leaf establishment. Our data provide novel insights into the complexity of a biotrophic interaction.


Assuntos
Regulação da Expressão Gênica de Plantas , Ustilago/patogenicidade , Zea mays/genética , Zea mays/metabolismo , Zea mays/microbiologia , Perfilação da Expressão Gênica , Genes de Plantas , Genoma de Planta , Interações Hospedeiro-Patógeno , Microscopia Confocal , Análise de Sequência com Séries de Oligonucleotídeos , Folhas de Planta/genética , Folhas de Planta/metabolismo , Folhas de Planta/microbiologia , Tumores de Planta/genética , Tumores de Planta/microbiologia , RNA de Plantas/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transcrição Gênica
5.
Plant Cell Environ ; 32(9): 1211-29, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19389052

RESUMO

MapMan is a software tool that supports the visualization of profiling data sets in the context of existing knowledge. Scavenger modules generate hierarchical and essentially non-redundant gene ontologies ('mapping files'). An ImageAnnotator module visualizes the data on a gene-by-gene basis on schematic diagrams ('maps') of biological processes. The PageMan module uses the same ontologies to statistically evaluate responses at the pathway or processes level. The generic structure of MapMan also allows it to be used for transcripts, proteins, enzymes and metabolites. MapMan was developed for use with Arabidopsis, but has already been extended for use with several other species. These tools are available as downloadable and web-based versions. After providing an introduction to the scope and use of MapMan, we present a case study where MapMan is used to analyse the transcriptional response of the crop plant maize to diurnal changes and an extension of the night. We then explain how MapMan can be customized to visually and systematically compare responses in maize and Arabidopsis. These analyses illustrate how MapMan can be used to analyse and compare global transcriptional responses between phylogenetically distant species, and show that analyses at the level of functional categories are especially useful in cross-species comparisons.


Assuntos
Genoma de Planta , Genômica/métodos , Software , Zea mays/genética , Arabidopsis/genética , Arabidopsis/metabolismo , Mapeamento Cromossômico , Fotoperíodo , RNA de Plantas/genética , Transcrição Gênica , Zea mays/metabolismo
6.
Plant Cell Environ ; 31(4): 518-47, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18088337

RESUMO

This paper characterizes the transcriptional and metabolic response of a chilling-tolerant species to an increasingly large decrease of the temperature. Arabidopsis Col-0 was grown at 20 degrees C and transferred to 17, 14, 12, 10 or 8 degrees C for 6 and 78 h, before harvesting the rosette and profiling >22 000 transcripts, >20 enzyme activities and >80 metabolites. Most parameters showed a qualitatively similar response across the entire temperature range, with the amplitude increasing as the temperature decreased. Transcripts typically showed large changes after 6 h, which were often damped by 78 h. Genes were induced for sucrose, proline, raffinose, tocopherol and polyamine synthesis, phenylpropanoid and flavonoid metabolism, fermentation, non-phosphorylating mitochondrial electron transport, RNA processing, and protein synthesis, targeting and folding. Genes were repressed for carbonic anhydrases, vacuolar invertase, and ethylene and jasmonic acid signalling. While some enzyme activities and metabolites changed rapidly, most changed slowly. After 6 h, there was an accumulation of phosphorylated intermediates, a shift of partitioning towards sucrose, and a perturbation of glycine decarboxylation and nitrogen metabolism. By 78 h, there was an increase of the overall protein content and many enzyme activities, a general increase of carbohydrates, organic and amino acids, and an increase of many stress-responsive metabolites including raffinose, proline, tocopherol and polyamines. When the responses of transcripts and metabolism were compared, there was little agreement after 6 h, but considerable agreement after 78 h. Comparison with the published studies indicated that much, but not all, of the response was orchestrated by the CBF programme. Overall, our results showed that transcription and metabolism responded in a continuous manner across a wide range of temperatures. The general increase of enzyme activities and metabolites emphasized the positive and compensatory nature of this response.


Assuntos
Arabidopsis/genética , Arabidopsis/metabolismo , Temperatura Baixa , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Genoma de Planta/genética , Genômica/métodos , Adaptação Fisiológica , Arabidopsis/enzimologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Carbono/metabolismo , Nitrogênio/metabolismo , Folhas de Planta/metabolismo , Transdução de Sinais , Fatores de Tempo , Transcrição Gênica/fisiologia
7.
BMC Bioinformatics ; 7: 535, 2006 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-17176458

RESUMO

BACKGROUND: Microarray technology has become a widely accepted and standardized tool in biology. The first microarray data analysis programs were developed to support pair-wise comparison. However, as microarray experiments have become more routine, large scale experiments have become more common, which investigate multiple time points or sets of mutants or transgenics. To extract biological information from such high-throughput expression data, it is necessary to develop efficient analytical platforms, which combine manually curated gene ontologies with efficient visualization and navigation tools. Currently, most tools focus on a few limited biological aspects, rather than offering a holistic, integrated analysis. RESULTS: Here we introduce PageMan, a multiplatform, user-friendly, and stand-alone software tool that annotates, investigates, and condenses high-throughput microarray data in the context of functional ontologies. It includes a GUI tool to transform different ontologies into a suitable format, enabling the user to compare and choose between different ontologies. It is equipped with several statistical modules for data analysis, including over-representation analysis and Wilcoxon statistical testing. Results are exported in a graphical format for direct use, or for further editing in graphics programs.PageMan provides a fast overview of single treatments, allows genome-level responses to be compared across several microarray experiments covering, for example, stress responses at multiple time points. This aids in searching for trait-specific changes in pathways using mutants or transgenics, analyzing development time-courses, and comparison between species. In a case study, we analyze the results of publicly available microarrays of multiple cold stress experiments using PageMan, and compare the results to a previously published meta-analysis.PageMan offers a complete user's guide, a web-based over-representation analysis as well as a tutorial, and is freely available at http://mapman.mpimp-golm.mpg.de/pageman/. CONCLUSION: PageMan allows multiple microarray experiments to be efficiently condensed into a single page graphical display. The flexible interface allows data to be quickly and easily visualized, facilitating comparisons within experiments and to published experiments, thus enabling researchers to gain a rapid overview of the biological responses in the experiments.


Assuntos
Perfilação da Expressão Gênica , Análise de Sequência com Séries de Oligonucleotídeos , Software , Interface Usuário-Computador , Sistemas de Gerenciamento de Base de Dados , Bases de Dados Genéticas , Software/tendências
8.
FEBS Lett ; 580(16): 3931-6, 2006 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-16806203

RESUMO

Ammonium is a primary source of N for plants, so knowing how it is transported, stored, and assimilated in plant cells is important for rational approaches to optimise N-use in agriculture. Electrophysiological studies of Arabidopsis AtAMT1;1 expressed in oocytes revealed passive, Deltapsi-driven transport of NH(4)(+) through this protein. Expression of AtAMT1;1 in a novel yeast mutant defective in endogenous ammonium transport and vacuolar acidification supported the above mechanism for AtAMT1;1 and revealed a central role for acid vacuoles in storage and retention of ammonia in cells. These results highlight the mechanistic differences between plant AMT proteins and related transporters in bacteria and animal cells, and suggest novel strategies to enhance nitrogen use efficiency in agriculture.


Assuntos
Arabidopsis , Proteínas de Transporte de Cátions/genética , Proteínas de Transporte de Cátions/metabolismo , Oócitos/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Compostos de Amônio Quaternário/metabolismo , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/metabolismo , Animais , Arabidopsis/genética , Expressão Gênica , Transporte de Íons , Modelos Biológicos , Vacúolos , Xenopus
9.
J Gen Physiol ; 126(6): 605-17, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16316977

RESUMO

Among all voltage-gated K+ channels from the model plant Arabidopsis thaliana, the weakly rectifying K+ channel (K(weak) channel) AKT2 displays unique gating properties. AKT2 is exceptionally regulated by phosphorylation: when nonphosphorylated AKT2 behaves as an inward-rectifying potassium channel; phosphorylation of AKT2 abolishes inward rectification by shifting its activation threshold far positive (>200 mV) so that it closes only at voltages positive of +100 mV. In its phosphorylated form, AKT2 is thus locked in the open state in the entire physiological voltage range. To understand the molecular grounds of this unique gating behavior, we generated chimeras between AKT2 and the conventional inward-rectifying channel KAT1. The transfer of the pore from KAT1 to AKT2 altered the permeation properties of the channel. However, the gating properties were unaffected, suggesting that the pore region of AKT2 is not responsible for the unique K(weak) gating. Instead, a lysine residue in S4, highly conserved among all K(weak) channels but absent from other plant K+ channels, was pinpointed in a site-directed mutagenesis approach. Substitution of the lysine by serine or aspartate abolished the "open-lock" characteristic and converted AKT2 into an inward-rectifying channel. Interestingly, phosphoregulation of the mutant AKT2-K197S appeared to be similar to that of the K(in) channel KAT1: as suggested by mimicking the phosphorylated and dephosphorylated states, phosphorylation induced a shift of the activation threshold of AKT2-K197S by about +50 mV. We conclude that the lysine residue K197 sensitizes AKT2 to phosphoregulation. The phosphorylation-induced reduction of the activation energy in AKT2 is approximately 6 kT larger than in the K197S mutant. It is discussed that this hypersensitive response of AKT2 to phosphorylation equips a cell with the versatility to establish a potassium gradient and to make efficient use of it.


Assuntos
Proteínas de Arabidopsis/fisiologia , Ativação do Canal Iônico/fisiologia , Canais de Potássio/fisiologia , Sequência de Aminoácidos , Proteínas de Arabidopsis/química , Eletrofisiologia , Dados de Sequência Molecular , Fosforilação , Canais de Potássio/química , Conformação Proteica
10.
Plant J ; 46(2): 269-81, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16623889

RESUMO

Plant outward-rectifying K+ channels mediate K+ efflux from guard cells during stomatal closure and from root cells into the xylem for root-shoot allocation of potassium (K). Intriguingly, the gating of these channels depends on the extracellular K+ concentration, although the ions carrying the current are derived from inside the cell. This K+ dependence confers a sensitivity to the extracellular K+ concentration ([K+]) that ensures that the channels mediate K+ efflux only, regardless of the [K+] prevailing outside. We investigated the mechanism of K+-dependent gating of the K+ channel SKOR of Arabidopsis by site-directed mutagenesis. Mutations affecting the intrinsic K+ dependence of gating were found to cluster in the pore and within the sixth transmembrane helix (S6), identifying an 'S6 gating domain' deep within the membrane. Mapping the SKOR sequence to the crystal structure of the voltage-dependent K+ channel KvAP from Aeropyrum pernix suggested interaction between the S6 gating domain and the base of the pore helix, a prediction supported by mutations at this site. These results offer a unique insight into the molecular basis for a physiologically important K+-sensory process in plants.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/fisiologia , Potássio/farmacologia , Superfamília Shaker de Canais de Potássio/fisiologia , Sequência de Aminoácidos , Substituição de Aminoácidos , Arabidopsis/genética , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/efeitos dos fármacos , Proteínas de Arabidopsis/genética , Ativação do Canal Iônico/fisiologia , Potenciais da Membrana/fisiologia , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Conformação Proteica , Proteínas Recombinantes/metabolismo , Superfamília Shaker de Canais de Potássio/química , Superfamília Shaker de Canais de Potássio/efeitos dos fármacos , Superfamília Shaker de Canais de Potássio/genética
11.
Biochem Biophys Res Commun ; 332(2): 465-73, 2005 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-15894288

RESUMO

Members of the Shaker-like plant K(+) channel family share a common structure, but are highly diverse in their function: they behave as either hyperpolarization-activated inward-rectifying (K(in)) channels, or leak-like (K(weak)) channels, or depolarization-activated outward-rectifying (K(out)) channels. Here we created 256 chimeras between the K(in) channel KAT1 and the K(out) channel SKOR. The chimeras were screened in a potassium-uptake deficient yeast strain to identify those, which mediate potassium inward currents, i.e., which are functionally equivalent to KAT1. This strategy allowed us to identify three chimeras which differ from KAT1 in three parts of the polypeptide: the cytosolic N-terminus, the cytosolic C-terminus, and the putative voltage-sensor S4. Additionally, mutations in the K(out) channel SKOR were generated in order to localize molecular entities underlying its depolarization activation. The triple mutant SKOR-D312N-M313L-I314G, carrying amino-acid changes in the S6 segment, was identified as a channel which did not display any rectification in the tested voltage-range.


Assuntos
Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Ativação do Canal Iônico/fisiologia , Canais de Potássio Corretores do Fluxo de Internalização/química , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Canais de Potássio/química , Canais de Potássio/metabolismo , Potássio/metabolismo , Sequência de Aminoácidos , Substituição de Aminoácidos , Proteínas de Arabidopsis/genética , Potenciais da Membrana/fisiologia , Dados de Sequência Molecular , Canais de Potássio/genética , Canais de Potássio Corretores do Fluxo de Internalização/genética , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Superfamília Shaker de Canais de Potássio , Relação Estrutura-Atividade
12.
Biophys J ; 87(2): 858-72, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15298894

RESUMO

SKOR and GORK are outward-rectifying plant potassium channels from Arabidopsis thaliana. They belong to the Shaker superfamily of voltage-dependent K(+) channels. Channels of this class are composed of four alpha-subunits and subunit assembly is a prerequisite for channel function. In this study the assembly mechanism of SKOR was investigated using the yeast two-hybrid system and functional assays in Xenopus oocytes and in yeast. We demonstrate that SKOR and GORK physically interact and assemble into heteromeric K(out) channels. Deletion mutants and chimeric proteins generated from SKOR and the K(in) channel alpha-subunit KAT1 revealed that the cytoplasmic C-terminus of SKOR determines channel assembly. Two domains that are crucial for channel assembly were identified: i), a proximal interacting region comprising a putative cyclic nucleotide-binding domain together with 33 amino acids just upstream of this domain, and ii), a distal interacting region showing some resemblance to the K(T) domain of KAT1. Both regions contributed differently to channel assembly. Whereas the proximal interacting region was found to be active on its own, the distal interacting region required an intact proximal interacting region to be active. K(out) alpha-subunits did not assemble with K(in) alpha-subunits because of the absence of interaction between their assembly sites.


Assuntos
Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Oócitos/metabolismo , Canais de Potássio/química , Canais de Potássio/metabolismo , Leveduras/metabolismo , Animais , Proteínas de Arabidopsis/genética , Sítios de Ligação , Células Cultivadas , Ativação do Canal Iônico/fisiologia , Potenciais da Membrana/fisiologia , Oócitos/química , Canais de Potássio/genética , Ligação Proteica , Estrutura Terciária de Proteína , Subunidades Proteicas/química , Subunidades Proteicas/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Superfamília Shaker de Canais de Potássio , Relação Estrutura-Atividade , Xenopus laevis , Leveduras/química
13.
Proc Natl Acad Sci U S A ; 100(9): 5549-54, 2003 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-12671068

RESUMO

Microscopic pores present in the epidermis of plant aerial organs, called stomata, allow gas exchanges between the inner photosynthetic tissue and the atmosphere. Regulation of stomatal aperture, preventing excess transpirational vapor loss, relies on turgor changes of two highly differentiated epidermal cells surrounding the pore, the guard cells. Increased guard cell turgor due to increased solute accumulation results in stomatal opening, whereas decreased guard cell turgor due to decreased solute accumulation results in stomatal closing. Here we provide direct evidence, based on reverse genetics approaches, that the Arabidopsis GORK Shaker gene encodes the major voltage-gated outwardly rectifying K(+) channel of the guard cell membrane. Expression of GORK dominant negative mutant polypeptides in transgenic Arabidopsis was found to strongly reduce outwardly rectifying K(+) channel activity in the guard cell membrane, and disruption of the GORK gene (T-DNA insertion knockout mutant) fully suppressed this activity. Bioassays on epidermal peels revealed that disruption of GORK activity resulted in impaired stomatal closure in response to darkness or the stress hormone abscisic acid [corrected]. Transpiration measurements on excised rosettes and intact plants (grown in hydroponic conditions or submitted to water stress) revealed that absence of GORK activity resulted in increased water consumption. The whole set of data indicates that GORK is likely to play a crucial role in adaptation to drought in fluctuating environments.


Assuntos
Arabidopsis/fisiologia , Canais de Potássio/fisiologia , Água/metabolismo , Arabidopsis/metabolismo , Técnicas de Patch-Clamp , Canais de Potássio/genética
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