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1.
Nat Commun ; 11(1): 4509, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32908151

RESUMO

Glycolysis is one of the primordial pathways of metabolism, playing a pivotal role in energy metabolism and biosynthesis. Glycolytic enzymes are known to form transient multi-enzyme assemblies. Here we examine the wider protein-protein interactions of plant glycolytic enzymes and reveal a moonlighting role for specific glycolytic enzymes in mediating the co-localization of mitochondria and chloroplasts. Knockout mutation of phosphoglycerate mutase or enolase resulted in a significantly reduced association of the two organelles. We provide evidence that phosphoglycerate mutase and enolase form a substrate-channelling metabolon which is part of a larger complex of proteins including pyruvate kinase. These results alongside a range of genetic complementation experiments are discussed in the context of our current understanding of chloroplast-mitochondrial interactions within photosynthetic eukaryotes.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Cloroplastos/enzimologia , Glicólise/fisiologia , Mitocôndrias/enzimologia , Arabidopsis/citologia , Proteínas de Arabidopsis/genética , Metabolismo Energético/fisiologia , Mutação , Fosfoglicerato Mutase/genética , Fosfoglicerato Mutase/metabolismo , Fosfopiruvato Hidratase/genética , Fosfopiruvato Hidratase/metabolismo , Fotossíntese/fisiologia , Plantas Geneticamente Modificadas , Mapeamento de Interação de Proteínas , Mapas de Interação de Proteínas/fisiologia , Piruvato Quinase/genética , Piruvato Quinase/metabolismo
2.
PLoS Comput Biol ; 16(9): e1007740, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32881861

RESUMO

The circadian clock is a complex system that plays many important roles in most organisms. Previously, many mathematical models have been used to sharpen our understanding of the Arabidopsis clock, which brought to light the roles of each transcriptional and post-translational regulations. However, the presence of both regulations, instead of either transcription or post-translation, raised curiosity of whether the combination of these two regulations is important for the clock's system. In this study, we built a series of simplified oscillators with different regulations to study the importance of post-translational regulation (specifically, 26S proteasome degradation) in the clock system. We found that a simple transcriptional-based oscillator can already generate sustained oscillation, but the oscillation can be easily destroyed in the presence of transcriptional leakage. Coupling post-translational control with transcriptional-based oscillator in a feed-forward loop will greatly improve the robustness of the oscillator in the presence of basal leakage. Using these general models, we were able to replicate the increased variability observed in the E3 ligase mutant for both plant and mammalian clocks. With this insight, we also predict a plausible regulator of several E3 ligase genes in the plant's clock. Thus, our results provide insights into and the plausible importance in coupling transcription and post-translation controls in the clock system.


Assuntos
Relógios Circadianos/genética , Modelos Biológicos , Processamento de Proteína Pós-Traducional/genética , Transcrição Genética/genética , Arabidopsis/genética , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Biologia Computacional , Retroalimentação Fisiológica , Regulação da Expressão Gênica de Plantas/genética , Complexo de Endopeptidases do Proteassoma/genética , Complexo de Endopeptidases do Proteassoma/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo
3.
Proc Biol Sci ; 287(1935): 20201397, 2020 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-32962543

RESUMO

Post-transcriptional regulation has far-reaching implications on the fate of RNAs. It is gaining increasing momentum as a critical component in adjusting global cellular transcript levels during development and in response to environmental stresses. In this process, RNA-binding proteins (RBPs) are indispensable chaperones that naturally bind RNA via one or multiple globular RNA-binding domains (RBDs) changing the function or fate of the bound RNAs. Despite the technical challenges faced in plants in large-scale studies, several hundreds of these RBPs have been discovered and elucidated globally over the past few years. Recent discoveries have more than doubled the number of proteins implicated in RNA interaction, including identification of RBPs lacking classical RBDs. This review will discuss these new emerging classes of RBPs, focusing on the current state of the RBP repertoire in Arabidopsis thaliana, including the diverse functional roles derived from quantitative studies implicating RBPs in abiotic stress responses. Notably, this review highlights that 836 RBPs are enriched as Arabidopsis RBPs while 1865 can be classified as candidate RBPs. The review will also outline outstanding areas within this field that require addressing to advance our understanding and potential biotechnological applications of RBPs.


Assuntos
Arabidopsis/fisiologia , Plantas/genética , Proteínas de Ligação a RNA/genética , RNA de Plantas/genética , Estresse Fisiológico
4.
Nat Commun ; 11(1): 4316, 2020 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-32859932

RESUMO

Plants utilize a UV-B (280 to 315 nm) photoreceptor UVR8 (UV RESISTANCE LOCUS 8) to sense environmental UV levels and regulate gene expression to avoid harmful UV effects. Uniquely, UVR8 uses intrinsic tryptophan for UV-B perception with a homodimer structure containing 26 structural tryptophan residues. However, besides 8 tryptophans at the dimer interface to form two critical pyramid perception centers, the other 18 tryptophans' functional role is unknown. Here, using ultrafast fluorescence spectroscopy, computational methods and extensive mutations, we find that all 18 tryptophans form light-harvesting networks and funnel their excitation energy to the pyramid centers to enhance light-perception efficiency. We determine the timescales of all elementary tryptophan-to-tryptophan energy-transfer steps in picoseconds to nanoseconds, in excellent agreement with quantum computational calculations, and finally reveal a significant leap in light-perception quantum efficiency from 35% to 73%. This photoreceptor is the first system discovered so far, to be best of our knowledge, using natural amino-acid tryptophans to form networks for both light harvesting and light perception.


Assuntos
Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Proteínas Cromossômicas não Histona/química , Proteínas Cromossômicas não Histona/metabolismo , Fotorreceptores de Plantas/química , Fotorreceptores de Plantas/metabolismo , Arabidopsis/metabolismo , Arabidopsis/fisiologia , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Proteínas Cromossômicas não Histona/genética , Transferência de Energia , Fluorescência , Cinética , Luz , Modelos Moleculares , Mutação , Conformação Proteica , Multimerização Proteica , Triptofano/metabolismo , Raios Ultravioleta
5.
Nat Commun ; 11(1): 3439, 2020 07 10.
Artigo em Inglês | MEDLINE | ID: mdl-32651385

RESUMO

Various stress conditions induce the nuclear translocation of cytosolic glyceraldehyde-3-phosphate dehydrogenase (GAPC), but its nuclear function in plant stress responses remains elusive. Here we show that GAPC interacts with a transcription factor to promote the expression of heat-inducible genes and heat tolerance in Arabidopsis. GAPC accumulates in the nucleus under heat stress. Overexpression of GAPC enhances heat tolerance of seedlings and the expression of heat-inducible genes whereas knockout of GAPCs has opposite effects. Screening of Arabidopsis transcription factors identifies nuclear factor Y subunit C10 (NF-YC10) as a GAPC-binding protein. The effects of GAPC overexpression are abolished when NF-YC10 is deficient, the heat-induced nuclear accumulation of GAPC is suppressed, or the GAPC-NF-YC10 interaction is disrupted. GAPC overexpression also enhances the binding ability of NF-YC10 to its target promoter. The results reveal a cellular and molecular mechanism for the nuclear moonlighting of a glycolytic enzyme in plant response to environmental changes.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Arabidopsis/fisiologia , Gliceraldeído-3-Fosfato Desidrogenases/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Fator de Ligação a CCAAT/genética , Fator de Ligação a CCAAT/metabolismo , Núcleo Celular/genética , Núcleo Celular/metabolismo , Núcleo Celular/fisiologia , Citosol/metabolismo , Citosol/fisiologia , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Gliceraldeído-3-Fosfato Desidrogenases/genética , Resposta ao Choque Térmico/genética , Resposta ao Choque Térmico/fisiologia , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Plantas Geneticamente Modificadas/fisiologia , Plântula/genética , Plântula/metabolismo , Plântula/fisiologia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
6.
Proc Natl Acad Sci U S A ; 117(28): 16667-16677, 2020 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-32601177

RESUMO

Plants are known for their outstanding capacity to recover from various wounds and injuries. However, it remains largely unknown how plants sense diverse forms of injury and canalize existing developmental processes into the execution of a correct regenerative response. Auxin, a cardinal plant hormone with morphogen-like properties, has been previously implicated in the recovery from diverse types of wounding and organ loss. Here, through a combination of cellular imaging and in silico modeling, we demonstrate that vascular stem cell death obstructs the polar auxin flux, much alike rocks in a stream, and causes it to accumulate in the endodermis. This in turn grants the endodermal cells the capacity to undergo periclinal cell division to repopulate the vascular stem cell pool. Replenishment of the vasculature by the endodermis depends on the transcription factor ERF115, a wound-inducible regulator of stem cell division. Although not the primary inducer, auxin is required to maintain ERF115 expression. Conversely, ERF115 sensitizes cells to auxin by activating ARF5/MONOPTEROS, an auxin-responsive transcription factor involved in the global auxin response, tissue patterning, and organ formation. Together, the wound-induced auxin accumulation and ERF115 expression grant the endodermal cells stem cell activity. Our work provides a mechanistic model for wound-induced stem cell regeneration in which ERF115 acts as a wound-inducible stem cell organizer that interprets wound-induced auxin maxima.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Ácidos Indolacéticos/metabolismo , Regeneração , Fatores de Transcrição/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Divisão Celular , Autorrenovação Celular , Regulação da Expressão Gênica de Plantas , Epiderme Vegetal/citologia , Epiderme Vegetal/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Fatores de Transcrição/genética
7.
PLoS One ; 15(6): e0234085, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32497140

RESUMO

Late embryogenesis abundant (LEA) proteins are widely involved in many adverse conditions among plants. In this study, we isolated a LEA4 gene from alfalfa (Medicago sativa L.) termed MsLEA4-4 via a homology cloning strategy. MsLEA4-4 encodes 166 amino acids, and the structural analysis showed that the gene contained five repeating TAQAAKEKTQQ amino acid motifs. There were a large number of α-helix in MsLEA4-4, and belongs to hydrophilic amino acid. Subcellular localization analysis showed that MsLEA4-4 was localized in the nucleus. The MsLEA4-4 promoter consisted of G-box and A-box elements, abscisic acid-responsive elements (ABREs), photo regulation and photoperiodic-controlling cis-acting elements, and endosperm expression motifs. The MsLEA4-4 overexpressing in Arabidopsis conferred late-germination phenotypes. Resistance of the overexpressed plants to abiotic stress significantly outperformed the wild-type (WT) plants. Under salt stress and abscisic acid treatment, with more lateral roots and higher chlorophyll content, the overexpressed plants has a higher survival rate measured against WT. Compared to those in the WT plants, the levels of soluble sugar and the activity of various antioxidant enzymes were elevated in the overexpressed plants, whereas the levels of proline and malondialdehyde were significantly reduced. The expression levels of several genes such as ABF3, ABI5, NCED5, and NCED9 increased markedly in the overexpressed plants compared to the WT under osmotic stress.


Assuntos
Arabidopsis/genética , Arabidopsis/fisiologia , Secas , Medicago sativa/genética , Estresse Oxidativo/genética , Proteínas de Plantas/genética , Estresse Salino/genética , Sequência de Aminoácidos , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Sequência de Bases , Clonagem Molecular , Expressão Gênica , Germinação , Pressão Osmótica , Proteínas de Plantas/química , Regiões Promotoras Genéticas/genética
8.
Chemosphere ; 257: 127248, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32526471

RESUMO

The toxicity characteristics of HBCD and resistance mechanism of flavonols are investigated based on physiological and metagenomic analysis. Toxicology research of HBCD on Arabidopsis thaliana (Col and fls1-3) not only shows the toxic effect of HBCD on plants, but also indicates that flavonols could improve plant resistance to HBCD, including root length, shoot biomass and chlorophyll content. Analysis of eggNOG and GO enrichment demonstrates that HBCD has toxic effect on both gene expression and protein function, which concentrates on energy production - conversion and amino acid transport - metabolism. Differential expressed genes in flavonols-treated groups indicates that flavonols regulate the metabolism of amino acids, cofactors and vitamins, which is involved in plant defense system against oxidative damage caused by HBCD stress. HBCD is believed to affect the synthesis of proteins via genes expression of ribosome biogenesis process. Flavonols could strengthen the plant resistance and alleviate toxic effect under HBCD stress.


Assuntos
Arabidopsis/fisiologia , Flavonóis/metabolismo , Hidrocarbonetos Bromados/toxicidade , Poluentes do Solo/toxicidade , Arabidopsis/metabolismo , Arabidopsis/microbiologia , Metagenoma , Solo , Poluentes do Solo/metabolismo
9.
Nat Commun ; 11(1): 3238, 2020 06 26.
Artigo em Inglês | MEDLINE | ID: mdl-32591540

RESUMO

The challenge of monitoring in planta dynamic changes of NADP(H) and NAD(H) redox states at the subcellular level is considered a major obstacle in plant bioenergetics studies. Here, we introduced two circularly permuted yellow fluorescent protein sensors, iNAP and SoNar, into Arabidopsis thaliana to monitor the dynamic changes in NADPH and the NADH/NAD+ ratio. In the light, photosynthesis and photorespiration are linked to the redox states of NAD(P)H and NAD(P) pools in several subcellular compartments connected by the malate-OAA shuttles. We show that the photosynthetic increases in stromal NADPH and NADH/NAD+ ratio, but not ATP, disappear when glycine decarboxylation is inhibited. These observations highlight the complex interplay between chloroplasts and mitochondria during photosynthesis and support the suggestions that, under normal conditions, photorespiration supplies a large amount of NADH to mitochondria, exceeding its NADH-dissipating capacity, and the surplus NADH is exported from the mitochondria to the cytosol through the malate-OAA shuttle.


Assuntos
Arabidopsis/fisiologia , Arabidopsis/efeitos da radiação , Luz , Proteínas Luminescentes/metabolismo , NADP/metabolismo , NAD/metabolismo , Fotossíntese/efeitos da radiação , Respiração Celular/efeitos da radiação , Cloroplastos/metabolismo , Citosol/metabolismo , Transporte de Elétrons/efeitos da radiação , Malatos/metabolismo , Mitocôndrias/metabolismo , Modelos Biológicos , Oxirredução , Peroxissomos/metabolismo , Plântula/metabolismo , Plântula/efeitos da radiação
10.
Proc Natl Acad Sci U S A ; 117(26): 15322-15331, 2020 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-32541049

RESUMO

Wound healing in plant tissues, consisting of rigid cell wall-encapsulated cells, represents a considerable challenge and occurs through largely unknown mechanisms distinct from those in animals. Owing to their inability to migrate, plant cells rely on targeted cell division and expansion to regenerate wounds. Strict coordination of these wound-induced responses is essential to ensure efficient, spatially restricted wound healing. Single-cell tracking by live imaging allowed us to gain mechanistic insight into the wound perception and coordination of wound responses after laser-based wounding in Arabidopsis root. We revealed a crucial contribution of the collapse of damaged cells in wound perception and detected an auxin increase specific to cells immediately adjacent to the wound. This localized auxin increase balances wound-induced cell expansion and restorative division rates in a dose-dependent manner, leading to tumorous overproliferation when the canonical TIR1 auxin signaling is disrupted. Auxin and wound-induced turgor pressure changes together also spatially define the activation of key components of regeneration, such as the transcription regulator ERF115. Our observations suggest that the wound signaling involves the sensing of collapse of damaged cells and a local auxin signaling activation to coordinate the downstream transcriptional responses in the immediate wound vicinity.


Assuntos
Arabidopsis/fisiologia , Ácidos Indolacéticos/metabolismo , Células Vegetais/fisiologia , Raízes de Plantas/fisiologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Divisão Celular , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Ácidos Indolacéticos/antagonistas & inibidores , Cinurenina/farmacologia , Lasers , Ftalimidas/farmacologia , Células Vegetais/efeitos dos fármacos , Regeneração/efeitos dos fármacos , Regeneração/fisiologia , Transdução de Sinais/fisiologia , Triazóis/farmacologia
11.
PLoS Genet ; 16(6): e1008847, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32559234

RESUMO

Plant cell growth requires the coordinated expansion of the protoplast and the cell wall, which is controlled by an elaborate system of cell wall integrity (CWI) sensors linking the different cellular compartments. LRR-eXtensins (LRXs) are cell wall-attached extracellular regulators of cell wall formation and high-affinity binding sites for RALF (Rapid ALkalinization Factor) peptide hormones that trigger diverse physiological processes related to cell growth. LRXs function in CWI sensing and in the case of LRX4 of Arabidopsis thaliana, this activity was shown to involve interaction with the transmembrane Catharanthus roseus Receptor-Like Kinase1-Like (CrRLK1L) protein FERONIA (FER). Here, we demonstrate that binding of RALF1 and FER is common to most tested LRXs of vegetative tissue, including LRX1, the main LRX protein of root hairs. Consequently, an lrx1-lrx5 quintuple mutant line develops shoot and root phenotypes reminiscent of the fer-4 knock-out mutant. The previously observed membrane-association of LRXs, however, is FER-independent, suggesting that LRXs bind not only FER but also other membrane-localized proteins to establish a physical link between intra- and extracellular compartments. Despite evolutionary diversification of various LRX proteins, overexpression of several chimeric LRX constructs causes cross-complementation of lrx mutants, indicative of comparable functions among members of this protein family. Suppressors of the pollen-growth defects induced by mutations in the CrRLK1Ls ANXUR1/2 also alleviate lrx1 lrx2-induced mutant root hair phenotypes. This suggests functional similarity of LRX-CrRLK1L signaling processes in very different cell types and indicates that LRX proteins are components of conserved processes regulating cell growth.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Parede Celular/metabolismo , Hormônios Peptídicos/metabolismo , Fosfotransferases/metabolismo , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Técnicas de Inativação de Genes , Genes de Plantas , Mutação , Fosfotransferases/genética , Raízes de Plantas/citologia , Raízes de Plantas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas , Pólen/citologia , Pólen/crescimento & desenvolvimento , Domínios Proteicos/genética , Mapas de Interação de Proteínas , Plântula/citologia , Plântula/crescimento & desenvolvimento , Transdução de Sinais/genética
12.
PLoS Genet ; 16(6): e1008892, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32569316

RESUMO

Nicotinamide adenine dinucleotide (NAD) is an essential coenzyme that has emerged as a central hub linking redox equilibrium and signal transduction in living organisms. The homeostasis of NAD is required for plant growth, development, and adaption to environmental cues. In this study, we isolated a chilling hypersensitive Arabidopsis thaliana mutant named qs-2 and identified the causal mutation in the gene encoding quinolinate synthase (QS) critical for NAD biosynthesis. The qs-2 mutant is also hypersensitive to salt stress and abscisic acid (ABA) but resistant to drought stress. The qs-2 mutant accumulates a reduced level of NAD and over-accumulates reactive oxygen species (ROS). The ABA-hypersensitivity of qs-2 can be rescued by supplementation of NAD precursors and by mutations in the ABA signaling components SnRK2s or RBOHF. Furthermore, ABA-induced over-accumulation of ROS in the qs-2 mutant is dependent on the SnRK2s and RBOHF. The expression of QS gene is repressed directly by ABI4, a transcription factor in the ABA response pathway. Together, our findings reveal an unexpected interplay between NAD biosynthesis and ABA and stress signaling, which is critical for our understanding of the regulation of plant growth and stress responses.


Assuntos
Arabidopsis/fisiologia , Regulação da Expressão Gênica de Plantas , Complexos Multienzimáticos/genética , Reguladores de Crescimento de Planta/metabolismo , Estresse Fisiológico/genética , Ácido Abscísico/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/isolamento & purificação , Proteínas de Arabidopsis/metabolismo , Retroalimentação Fisiológica , Perfilação da Expressão Gênica , Complexos Multienzimáticos/isolamento & purificação , Complexos Multienzimáticos/metabolismo , Mutação , NAD/biossíntese , NADPH Oxidases/metabolismo , Plantas Geneticamente Modificadas , Proteínas Serina-Treonina Quinases/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Transdução de Sinais/fisiologia , Fatores de Transcrição/genética , Fatores de Transcrição/isolamento & purificação , Fatores de Transcrição/metabolismo
13.
PLoS Genet ; 16(6): e1008873, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32584819

RESUMO

The regulation of leaf size has been studied for decades. Enhancement of post-mitotic cell expansion triggered by impaired cell proliferation in Arabidopsis is an important process for leaf size regulation, and is known as compensation. This suggests a key interaction between cell proliferation and cell expansion during leaf development. Several studies have highlighted the impact of this integration mechanism on leaf size determination; however, the molecular basis of compensation remains largely unknown. Previously, we identified extra-small sisters (xs) mutants which can suppress compensated cell enlargement (CCE) via a specific defect in cell expansion within the compensation-exhibiting mutant, angustifolia3 (an3). Here we revealed that one of the xs mutants, namely xs2, can suppress CCE not only in an3 but also in other compensation-exhibiting mutants erecta (er) and fugu2. Molecular cloning of XS2 identified a deleterious mutation in CATION CALCIUM EXCHANGER 4 (CCX4). Phytohormone measurement and expression analysis revealed that xs2 shows hyper activation of the salicylic acid (SA) response pathway, where activation of SA response can suppress CCE in compensation mutants. All together, these results highlight the regulatory connection which coordinates compensation and SA response.


Assuntos
Antiporters/genética , Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Reguladores de Crescimento de Planta/metabolismo , Folhas de Planta/crescimento & desenvolvimento , Ácido Salicílico/metabolismo , Proteínas de Arabidopsis/genética , Cálcio/metabolismo , Cátions Bivalentes/metabolismo , Crescimento Celular , Proliferação de Células/genética , Regulação da Expressão Gênica de Plantas , Mutação com Perda de Função , Tamanho do Órgão/genética , Folhas de Planta/citologia , Folhas de Planta/metabolismo , Plantas Geneticamente Modificadas , Transdução de Sinais/genética
14.
Proc Natl Acad Sci U S A ; 117(23): 13127-13137, 2020 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-32434921

RESUMO

Stomatal guard cells control gas exchange that allows plant photosynthesis but limits water loss from plants to the environment. In Arabidopsis, stomatal development is mainly controlled by a signaling pathway comprising peptide ligands, membrane receptors, a mitogen-activated protein kinase (MAPK) cascade, and a set of transcription factors. The initiation of the stomatal lineage requires the activity of the bHLH transcription factor SPEECHLESS (SPCH) with its partners. Multiple kinases were found to regulate SPCH protein stability and function through phosphorylation, yet no antagonistic protein phosphatase activities have been identified. Here, we identify the conserved PP2A phosphatases as positive regulators of Arabidopsis stomatal development. We show that mutations in genes encoding PP2A subunits result in lowered stomatal production in Arabidopsis Genetic analyses place the PP2A function upstream of SPCH. Pharmacological treatments support a role for PP2A in promoting SPCH protein stability. We further find that SPCH directly binds to the PP2A-A subunits in vitro. In plants, nonphosphorylatable SPCH proteins are less affected by PP2A activity levels. Thus, our research suggests that PP2A may function to regulate the phosphorylation status of the master transcription factor SPCH in stomatal development.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Regulação da Expressão Gênica de Plantas/fisiologia , Estômatos de Plantas/crescimento & desenvolvimento , Proteína Fosfatase 2/metabolismo , Proteínas de Arabidopsis/antagonistas & inibidores , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/isolamento & purificação , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Mutação , Fosforilação/fisiologia , Estômatos de Plantas/efeitos dos fármacos , Plantas Geneticamente Modificadas , Proteína Fosfatase 2/antagonistas & inibidores , Proteína Fosfatase 2/genética , Proteína Fosfatase 2/isolamento & purificação , Estabilidade Proteica/efeitos dos fármacos , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Tabaco/genética
15.
Nat Commun ; 11(1): 2065, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-32358518

RESUMO

Natural environments require organisms to possess robust mechanisms allowing responses to seasonal trends. In Arabidopsis halleri, the flowering regulator AhgFLC shows upregulation and downregulation phases along with long-term past temperature, but the underlying machinery remains elusive. Here, we investigate the seasonal dynamics of histone modifications, H3K27me3 and H3K4me3, at AhgFLC in a natural population. Our advanced modelling and transplant experiments reveal that H3K27me3-mediated chromatin regulation at AhgFLC provides two essential properties. One is the ability to respond to the long-term temperature trends via bidirectional interactions between H3K27me3 and H3K4me3; the other is the ratchet-like character of the AhgFLC system, i.e. reversible in the entire perennial life cycle but irreversible during the upregulation phase. Furthermore, we show that the long-term temperature trends are locally indexed at AhgFLC in the form of histone modifications. Our study provides a more comprehensive understanding of H3K27me3 function at AhgFLC in a complex natural environment.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Cromatina/química , Flores/fisiologia , Histonas/metabolismo , Proteínas de Domínio MADS/genética , Arabidopsis/fisiologia , Epigênese Genética , Flores/genética , Regulação da Expressão Gênica de Plantas , Código das Histonas , Japão , Estações do Ano , Temperatura
16.
Nat Commun ; 11(1): 2532, 2020 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-32439842

RESUMO

Facilitation studies typically compare plants under differential stress levels with and without neighbors, while the density of neighbors has rarely been addressed. However, recent empirical studies indicate that facilitation may be density-dependent too and peak at intermediate neighbor densities. Here, we propose a conceptual model to incorporate density-dependence into theory about changes of plant-plant interactions under stress. To test our predictions, we combine an individual-based model incorporating both facilitative response and effect, with an experiment using salt stress and Arabidopsis thaliana. Theoretical and experimental results are strikingly consistent: (1) the intensity of facilitation peaks at intermediate density, and this peak shifts to higher densities with increasing stress; (2) this shift further modifies the balance between facilitation and competition such that the stress-gradient hypothesis applies only at high densities. Our model suggests that density-dependence must be considered for predicting plant-plant interactions under environmental change.


Assuntos
Ecossistema , Fenômenos Fisiológicos Vegetais , Estresse Fisiológico , Aclimatação , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/fisiologia , Modelos Biológicos , Desenvolvimento Vegetal , Dinâmica Populacional
17.
PLoS Genet ; 16(5): e1008807, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32407354

RESUMO

Pollen wall consists of several complex layers which form elaborate species-specific patterns. In Arabidopsis, the transcription factor ABORTED MICROSPORE (AMS) is a master regulator of exine formation, and another transcription factor, TRANSPOSABLE ELEMENT SILENCING VIA AT-HOOK (TEK), specifies formation of the nexine layer. However, knowledge regarding the temporal regulatory roles of TEK in pollen wall development is limited. Here, TEK-GFP driven by the AMS promoter was prematurely expressed in the tapetal nuclei, leading to complete male sterility in the pAMS:TEK-GFP (pat) transgenic lines with the wild-type background. Cytological observations in the pat anthers showed impaired callose synthesis and aberrant exine patterning. CALLOSE SYNTHASE5 (CalS5) is required for callose synthesis, and expression of CalS5 in pat plants was significantly reduced. We demonstrated that TEK negatively regulates CalS5 expression after the tetrad stage in wild-type anthers and further discovered that premature TEK-GFP in pat directly represses CalS5 expression through histone modification. Our findings show that TEK flexibly mediates its different functions via different temporal regulation, revealing that the temporal regulation of TEK is essential for exine patterning. Moreover, the result that the repression of CalS5 by TEK after the tetrad stage coincides with the timing of callose wall dissolution suggests that tapetum utilizes temporal regulation of genes to stop callose wall synthesis, which, together with the activation of callase activity, achieves microspore release and pollen wall patterning.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Pólen/fisiologia , Fatores de Transcrição/metabolismo , Arabidopsis/fisiologia , Proteínas de Arabidopsis/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Epigênese Genética , Regulação da Expressão Gênica de Plantas , Glucosiltransferases/metabolismo , Histonas/metabolismo , Metilação , Plantas Geneticamente Modificadas/fisiologia , Pólen/genética , Regiões Promotoras Genéticas
18.
Nat Commun ; 11(1): 2395, 2020 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-32409656

RESUMO

Pollen tubes are highly polarized tip-growing cells that depend on cytosolic pH gradients for signaling and growth. Autoinhibited plasma membrane proton (H+) ATPases (AHAs) have been proposed to energize pollen tube growth and underlie cell polarity, however, mechanistic evidence for this is lacking. Here we report that the combined loss of AHA6, AHA8, and AHA9 in Arabidopsis thaliana delays pollen germination and causes pollen tube growth defects, leading to drastically reduced fertility. Pollen tubes of aha mutants had reduced extracellular proton (H+) and anion fluxes, reduced cytosolic pH, reduced tip-to-shank proton gradients, and defects in actin organization. Furthermore, mutant pollen tubes had less negative membrane potentials, substantiating a mechanistic role for AHAs in pollen tube growth through plasma membrane hyperpolarization. Our findings define AHAs as energy transducers that sustain the ionic circuit defining the spatial and temporal profiles of cytosolic pH, thereby controlling downstream pH-dependent mechanisms essential for pollen tube elongation, and thus plant fertility.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Tubo Polínico/crescimento & desenvolvimento , Polinização/fisiologia , ATPases Translocadoras de Prótons/metabolismo , Proteínas de Arabidopsis/genética , Membrana Celular/metabolismo , Polaridade Celular/fisiologia , Citosol/metabolismo , Técnicas de Silenciamento de Genes , Germinação/fisiologia , Concentração de Íons de Hidrogênio , Potenciais da Membrana/fisiologia , Mutação , Plantas Geneticamente Modificadas , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , ATPases Translocadoras de Prótons/genética , Análise Espaço-Temporal
19.
J Plant Physiol ; 250: 153182, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32428693

RESUMO

Stomatal aperture is tightly regulated in order to achieve the best compromise between gas exchange and water conservation. Steady-state (basal) stomatal aperture is therefore understandably a key component in plant fitness. It has been shown previously in tomato that DELLA proteins act as positive regulators of closure of stomata, and their action is enhanced by the hormone ABA, which is itself important in mediating drought stress tolerance. DELLAs are regulated by a variety of signals which promote plant growth, most notably the hormones gibberellins, which have been shown to promote stomatal opening. We have found that DELLA proteins are also used in Arabidopsis for regulating basal stomatal aperture. We also discovered that the perception of endogenous gibberellins via the GID1 receptors is necessary for optimal basal stomatal aperture.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/fisiologia , Estômatos de Plantas/fisiologia , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo
20.
Proc Natl Acad Sci U S A ; 117(16): 9101-9111, 2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-32245810

RESUMO

In eukaryotic photosynthetic organisms, the conversion of solar into chemical energy occurs in thylakoid membranes in the chloroplast. How thylakoid membranes are formed and maintained is poorly understood. However, previous observations of vesicles adjacent to the stromal side of the inner envelope membrane of the chloroplast suggest a possible role of membrane transport via vesicle trafficking from the inner envelope to the thylakoids. Here we show that the model plant Arabidopsis thaliana has a chloroplast-localized Sec14-like protein (CPSFL1) that is necessary for photoautotrophic growth and vesicle formation at the inner envelope membrane of the chloroplast. The cpsfl1 mutants are seedling lethal, show a defect in thylakoid structure, and lack chloroplast vesicles. Sec14 domain proteins are found only in eukaryotes and have been well characterized in yeast, where they regulate vesicle budding at the trans-Golgi network. Like the yeast Sec14p, CPSFL1 binds phosphatidylinositol phosphates (PIPs) and phosphatidic acid (PA) and acts as a phosphatidylinositol transfer protein in vitro, and expression of Arabidopsis CPSFL1 can complement the yeast sec14 mutation. CPSFL1 can transfer PIP into PA-rich membrane bilayers in vitro, suggesting that CPSFL1 potentially facilitates vesicle formation by trafficking PA and/or PIP, known regulators of membrane trafficking between organellar subcompartments. These results underscore the role of vesicles in thylakoid biogenesis and/or maintenance. CPSFL1 appears to be an example of a eukaryotic cytosolic protein that has been coopted for a function in the chloroplast, an organelle derived from endosymbiosis of a cyanobacterium.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Proteínas de Transferência de Fosfolipídeos/metabolismo , Fotossíntese , Tilacoides/metabolismo , Proteínas de Arabidopsis/genética , Microscopia Eletrônica de Transmissão , Mutação , Ácidos Fosfatídicos/metabolismo , Fosfatos de Fosfatidilinositol/metabolismo , Proteínas de Transferência de Fosfolipídeos/genética , Plantas Geneticamente Modificadas , Domínios Proteicos , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Plântula , Homologia de Sequência de Aminoácidos , Tilacoides/ultraestrutura
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