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1.
Plant Physiol ; 2021 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-34618093

RESUMO

Salicylic acid (SA) plays an important role for plant immunity, especially resistance against biotrophic pathogens. SA quickly accumulates after pathogen attack to activate downstream immunity events and is normally associated with a tradeoff in plant growth. Therefore, the SA level in plants has to be strictly controlled when pathogens are absent, but how this occurs is not well understood. Previously we found that in Arabidopsis (Arabidopsis thaliana), HISTONE DEACETYLASE 6 (HDA6), a negative regulator of gene expression, plays an essential role in plant immunity since its mutation allele shining 5 (shi5) exhibits autoimmune phenotypes. Here we report that this role is mainly through suppression of SA biosynthesis: first, the autoimmune phenotypes and higher resistance to Pst DC3000 of shi5 mutants depended on SA; second, SA significantly accumulated in shi5 mutants; third, HDA6 repressed SA biosynthesis by directly controlling the expression of CALMODULIN BINDING PROTEIN 60g (CBP60g) and SYSTEMIC ACQUIRED RESISTANCE DEFICIENT 1 (SARD1). HDA6 bound to the chromatin of CBP60g and SARD1 promoter regions, and histone H3 acetylation was highly enriched within these regions. Furthermore, the transcriptome of shi5 mutants mimicked that of plants treated with exogenous SA or attacked by pathogens. All these data suggest that HDA6 is vital for plants in finely controlling the SA level to regulate plant immunity.

2.
Planta ; 254(5): 98, 2021 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-34657208

RESUMO

MAIN CONCLUSION: Mota Maradi is a sorghum line that exhibits holistic salinity tolerance mechanisms, making it a viable potential donor in breeding efforts for improved sorghum lines. High soil salinity is one of the global challenges for crop growth and productivity. Understanding the salinity tolerance mechanisms in crops is necessary for genetic breeding of salinity-tolerant crops. In this study, physiological and molecular mechanisms in sorghum were identified through a comparative analysis between a Nigerien salinity-tolerant sorghum landrace, Mota Maradi, and the reference sorghum line, BTx623. Significant differences on physiological performances were observed, particularly on growth and biomass gain, photosynthetic rate, and the accumulation of Na+, K+, proline, and sucrose. Transcriptome profiling of the leaves, leaf sheaths, stems, and roots revealed contrasting differentially expressed genes (DEGs) in Mota Maradi and BTx623 which supports the physiological observations from both lines. Among the DEGs, ion transporters such as HKT, NHX, AKT, HAK5, and KUP3 were likely responsible for the differences in Na+ and K+ accumulation. Meanwhile, DEGs involved in photosynthesis, cellular growth, signaling, and ROS scavenging were also identified between these two genotypes. Functional and pathway analysis of the DEGs has revealed that these processes work in concert and are crucial in elevated salinity tolerance in Mota Maradi. Our findings indicate how different complex processes work synergistically for salinity stress tolerance in sorghum. This study also highlights the unique adaptation of landraces toward their respective ecosystems, and their strong potential as genetic resources for future plant breeding endeavors.


Assuntos
Tolerância ao Sal , Sorghum , Ecossistema , Perfilação da Expressão Gênica , Melhoramento Vegetal , Salinidade , Tolerância ao Sal/genética , Sorghum/genética , Estresse Fisiológico , Transcriptoma
3.
Nat Commun ; 12(1): 2456, 2021 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-33911084

RESUMO

The phytohormone abscisic acid (ABA) is crucial for plant responses to environmental challenges. The SNF1-regulated protein kinase 2s (SnRK2s) are key components in ABA-receptor coupled core signaling, and are rapidly phosphorylated and activated by ABA. Recent studies have suggested that Raf-like protein kinases (RAFs) participate in ABA-triggered SnRK2 activation. In vitro kinase assays also suggest the existence of autophosphorylation of SnRK2s. Thus, how SnRK2 kinases are quickly activated during ABA signaling still needs to be clarified. Here, we show that both B2 and B3 RAFs directly phosphorylate SnRK2.6 in the kinase activation loop. This transphosphorylation by RAFs is essential for SnRK2 activation. The activated SnRK2s then intermolecularly trans-phosphorylate other SnRK2s that are not yet activated to amplify the response. High-order Arabidopsis mutants lacking multiple B2 and B3 RAFs show ABA hyposensitivity. Our findings reveal a unique initiation and amplification mechanism of SnRK2 activation in ABA signaling in higher plants.


Assuntos
Ácido Abscísico/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas Quinases/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica de Plantas/genética , Fosforilação , Proteínas Quinases/genética , Proteínas Serina-Treonina Quinases/genética , Transdução de Sinais/genética
4.
New Phytol ; 229(4): 2035-2049, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33048351

RESUMO

Plant stomata play a crucial role in leaf function, controlling water transpiration in response to environmental stresses and modulating the gas exchange necessary for photosynthesis. The phytohormone abscisic acid (ABA) promotes stomatal closure and inhibits light-induced stomatal opening. The Arabidopsis thaliana E3 ubiquitin ligase COP1 functions in ABA-mediated stomatal closure. However, the underlying molecular mechanisms are still not fully understood. Yeast two-hybrid assays were used to identify ABA signaling components that interact with COP1, and biochemical, molecular and genetic studies were carried out to elucidate the regulatory role of COP1 in ABA signaling. The cop1 mutants are hyposensitive to ABA-triggered stomatal closure under light and dark conditions. COP1 interacts with and ubiquitinates the Arabidopsis clade A type 2C phosphatases (PP2Cs) ABI/HAB group and AHG3, thus triggering their degradation. Abscisic acid enhances the COP1-mediated degradation of these PP2Cs. Mutations in ABI1 and AHG3 partly rescue the cop1 stomatal phenotype and the phosphorylation level of OST1, a crucial SnRK2-type kinase in ABA signaling. Our data indicate that COP1 is part of a novel signaling pathway promoting ABA-mediated stomatal closure by regulating the stability of a subset of the Clade A PP2Cs. These findings provide novel insights into the interplay between ABA and the light signaling component in the modulation of stomatal movement.


Assuntos
Ácido Abscísico , Proteínas de Arabidopsis/fisiologia , Fosfoproteínas Fosfatases/fisiologia , Estômatos de Plantas/fisiologia , Ubiquitina-Proteína Ligases/fisiologia , Complexo I de Proteína do Envoltório , Mutação/genética , Proteínas Quinases/fisiologia
6.
BMC Plant Biol ; 20(1): 550, 2020 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-33287728

RESUMO

BACKGROUND: Cadmium (Cd) accumulation in crops affects the yield and quality of crops and harms human health. The application of selenium (Se) can reduce the absorption and transport of Cd in winter wheat. RESULTS: The results showed that increasing Se supply significantly decreased Cd concentration and accumulation in the shoot and root of winter wheat and the root-to-shoot translocation of Cd. Se application increased the root length, surface area and root volume but decreased the average root diameter. Increasing Se supply significantly decreased Cd concentration in the cell wall, soluble fraction and cell organelles in root and shoot. An increase in Se supply inhibited Cd distribution in the organelles of shoot and root but enhanced Cd distribution in the soluble fraction of shoot and the cell wall of root. The Se supply also decreased the proportion of active Cd (ethanol-extractable (FE) Cd and deionized water-extractable (FW) Cd) in root. In addition, the expression of TaNramp5-a, TaNramp5-b, TaHMA3-a, TaHMA3-b and TaHMA2 significantly increased with increasing Cd concentration in root, and the expression of TaNramp5-a, TaNramp5-b and TaHMA2 in root was downregulated by increasing Se supply, regardless of Se supply or Cd stress. The expression of TaHMA3-b in root was significantly downregulated by 10 µM Se at both the 5 µM and 25 µM Cd level but upregulated by 5 µM Se at the 25 µM Cd level. The expression of TaNramp5-a, TaNramp5-b, TaHMA3-a, TaHMA3-b and TaHMA2 in shoot was downregulated by increasing Se supply at 5 µM Cd level, and 5 µM Se upregulated the expression of those genes in shoot at 25 µM Cd level. CONCLUSIONS: The results confirm that Se application limits Cd accumulation in wheat by regulating the subcellular distribution and chemical forms of Cd in winter wheat tissues, as well as the expression of TaNramp5-a, TaNramp5-b and TaHMA2 in root.


Assuntos
Cádmio/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Proteínas de Plantas/metabolismo , Selênio/metabolismo , Triticum/metabolismo , Transporte Biológico , Cádmio/química , Regulação da Expressão Gênica de Plantas , Proteínas de Membrana Transportadoras/genética , Proteínas de Plantas/genética , Raízes de Plantas/química , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Brotos de Planta/química , Brotos de Planta/genética , Brotos de Planta/metabolismo , Plântula/química , Plântula/genética , Plântula/metabolismo , Frações Subcelulares/química , Triticum/química , Triticum/genética
7.
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 Plantas/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
8.
Plant Mol Biol ; 103(4-5): 511-525, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32279151

RESUMO

KEY MESSAGE: TPST is involved in fructose signaling to regulate the root development and expression of genes in biological processes including auxin biosynthesis and accumulation in Arabidopsis. Sulfonation of proteins by tyrosine protein sulfotransferases (TPST) has been implicated in many important biological processes in eukaryotic organisms. Arabidopsis possesses a single TPST gene and its role in auxin homeostasis and root development has been reported. Here we show that the Arabidopsis tpst mutants are hypersensitive to fructose. In contrast to sucrose and glucose, fructose represses primary root growth of various ecotypes of Arabidopsis at low concentrations. RNA-seq analysis identified 636 differentially expressed genes (DEGs) in Col-0 seedlings in response to fructose verses glucose. GO and KEGG analyses of the DEGs revealed that fructose down-regulates genes involved in photosynthesis, glucosinolate biosynthesis and IAA biosynthesis, but up-regulates genes involved in the degradation of branched amino acids, sucrose starvation response, and dark response. The fructose responsive DEGs in the tpst mutant largely overlapped with that in Col-0, and most DEGs in tpst displayed larger changes than in Col-0. Interestingly, the fructose up-regulated DEGs includes genes encoding two AtTPST substrate proteins, Phytosulfokine 2 (PSK2) and Root Meristem Growth Factor 7 (RGF7). Synthesized peptides of PSK-α and RGF7 could restore the fructose hypersensitivity of tpst mutant plants. Furthermore, auxin distribution and accumulation at the root tip were affected by fructose and the tpst mutation. Our findings suggest that fructose serves as a signal to regulate the expression of genes involved in various biological processes including auxin biosynthesis and accumulation, and that modulation of auxin accumulation and distribution in roots by fructose might be partly mediated by the TPST substrate genes PSK-α and RGF7.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Frutose/metabolismo , Raízes de Plantas/metabolismo , Sulfotransferases/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Glucose/metabolismo , Ácidos Indolacéticos/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Meristema/metabolismo , Hormônios Peptídicos/genética , Hormônios Peptídicos/metabolismo , Proteínas de Plantas , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas , Plântula/crescimento & desenvolvimento , Transdução de Sinais , Sulfotransferases/genética , Transcriptoma
9.
Sci China Life Sci ; 63(5): 635-674, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32246404

RESUMO

Abiotic stresses and soil nutrient limitations are major environmental conditions that reduce plant growth, productivity and quality. Plants have evolved mechanisms to perceive these environmental challenges, transmit the stress signals within cells as well as between cells and tissues, and make appropriate adjustments in their growth and development in order to survive and reproduce. In recent years, significant progress has been made on many fronts of the stress signaling research, particularly in understanding the downstream signaling events that culminate at the activation of stress- and nutrient limitation-responsive genes, cellular ion homeostasis, and growth adjustment. However, the revelation of the early events of stress signaling, particularly the identification of primary stress sensors, still lags behind. In this review, we summarize recent work on the genetic and molecular mechanisms of plant abiotic stress and nutrient limitation sensing and signaling and discuss new directions for future studies.


Assuntos
Plantas/genética , Plantas/metabolismo , Solo/química , Estresse Fisiológico/fisiologia , Canais de Cálcio/metabolismo , Regulação da Expressão Gênica de Plantas , Metais Pesados/metabolismo , Fosforilação , Desenvolvimento Vegetal/genética , Proteínas de Plantas/metabolismo , Transdução de Sinais , Estresse Fisiológico/genética , Fatores de Transcrição/metabolismo
10.
EMBO J ; 39(10): e103256, 2020 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-32134151

RESUMO

Domestication has resulted in reduced salt tolerance in tomato. To identify the genetic components causing this deficiency, we performed a genome-wide association study (GWAS) for root Na+ /K+ ratio in a population consisting of 369 tomato accessions with large natural variations. The most significant variations associated with root Na+ /K+ ratio were identified within the gene SlHAK20 encoding a member of the clade IV HAK/KUP/KT transporters. We further found that SlHAK20 transports Na+ and K+ and regulates Na+ and K+ homeostasis under salt stress conditions. A variation in the coding sequence of SlHAK20 was found to be the causative variant associated with Na+ /K+ ratio and confer salt tolerance in tomato. Knockout mutations in tomato SlHAK20 and the rice homologous genes resulted in hypersensitivity to salt stress. Together, our study uncovered a previously unknown molecular mechanism of salt tolerance responsible for the deficiency in salt tolerance in cultivated tomato varieties. Our findings provide critical information for molecular breeding to improve salt tolerance in tomato and other crops.


Assuntos
Mutação com Perda de Função , Lycopersicon esculentum/crescimento & desenvolvimento , Tolerância ao Sal , ATPase Trocadora de Sódio-Potássio/genética , Embaralhamento de DNA , Domesticação , Regulação da Expressão Gênica de Plantas , Estudo de Associação Genômica Ampla , Desequilíbrio de Ligação , Lycopersicon esculentum/genética , Família Multigênica , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo
11.
Plant Physiol ; 182(4): 1991-2005, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32024697

RESUMO

Maintaining the structural integrity of the photosynthetic apparatus during dehydration is critical for effective recovery of photosynthetic activity upon rehydration in a variety of desiccation-tolerant plants, but the underlying molecular mechanism is largely unclear. The subaerial cyanobacterium Nostoc flagelliforme can survive extreme dehydration conditions and quickly recovers its photosynthetic activity upon rehydration. In this study, we found that the expression of the molecular chaperone NfDnaK2 was substantially induced by dehydration, and NfDnaK2 proteins were primarily localized in the thylakoid membrane. NfDnaJ9 was identified to be the cochaperone partner of NfDnaK2, and their encoding genes shared similar transcriptional responses to dehydration. NfDnaJ9 interacted with the NfFtsH2 protease involved in the degradation of damaged D1 protein. Heterologous expression of NfdnaK2 enhanced PSII repair and drought tolerance in transgenic Nostoc sp. PCC 7120. Furthermore, the nitrate reduction (NarL)/nitrogen fixation (FixJ) family transcription factors response regulator (NfRre1) and photosynthetic electron transport-dependent regulator (NfPedR) were identified as putative positive regulators capable of binding to the promoter region of NfdnaK2 and they may mediate dehydration-induced expression of NfdnaK2 in N. flagelliforme Our findings provide novel insights into the molecular mechanism of desiccation tolerance in some xerotolerant microorganisms, which could facilitate future synthetic approaches to the creation of extremophiles in microorganisms and plants.


Assuntos
Proteínas de Bactérias/metabolismo , Cianobactérias/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Desidratação , Dessecação , Secas , Nitratos/metabolismo , Fixação de Nitrogênio , Fotossíntese/fisiologia , Tilacoides/metabolismo
12.
BMC Genomics ; 21(1): 40, 2020 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-31931705

RESUMO

BACKGROUND: Boehmeria nivea L. Gaud (Ramie) produces one of the longest natural fibers in nature. The bark of ramie mainly comprises of the phloem tissue of stem and is the raw material for fiber. Therefore, identifying the molecular regulation of phloem development is important for understanding of bast fiber biosynthesis and improvement of fiber quality in ramie. RESULTS: In this study, we collected top bud (TB), bark from internode elongating region (ER) and bark from internode fully elongated region (FER) from the ramie variety Zhongzhu No. 1. Histological study indicated that these samples contain phloem tissues at different developmental and maturation stages, with a higher degree of maturation of phloem tissue in FER. RNA sequencing (RNA-seq) was performed and de novo transcriptome was assembled. Unigenes and differentially expressed genes (DEGs) in these three samples were identified. The analysis of DEGs by using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed clear differences in gene expression between ER and FER. Some unigenes involved in secondary cell wall biosynthesis were up-regulated in both ER and FER, while unigenes for some cell wall components or cell wall modifications showed differential expression between ER and FER. In addition, the ethylene respond factors (ERFs) in the ethylene signaling pathway were up-regulated in FER, and ent-kaurenoic acid oxidase (KAO) and GA 20-oxidase (GA20ox) for gibberellins biosynthesis were up-regulated while GA 2-oxidase (GA2ox) for gibberellin inactivation was down-regulated in FER. CONCLUSIONS: Both morphological study and gene expression analysis supported a burst of phloem and vascular developmental processes during the fiber maturation in the ramie stem, and ethylene and gibberellin are likely to be involved in this process. Our findings provide novel insights into the phloem development and fiber maturation in ramie, which could be useful for fiber improvement in ramie and other fiber crops.


Assuntos
Boehmeria/fisiologia , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Casca de Planta/genética , Característica Quantitativa Herdável , Transcriptoma , Biologia Computacional/métodos , Ontologia Genética , Anotação de Sequência Molecular , Floema/genética , Desenvolvimento Vegetal/genética
13.
Cell Rep ; 30(1): 229-242.e5, 2020 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-31914389

RESUMO

Plants respond to cold stress by inducing the expression of transcription factors that regulate downstream genes to confer tolerance to freezing. We screened an Arabidopsis transfer DNA (T-DNA) insertion library and identified a cold-hypersensitive mutant, which we named stch4 (sensitive to chilling 4). STCH4/REIL2 encodes a ribosomal biogenesis factor that is upregulated upon cold stress. Overexpression of STCH4 confers chilling and freezing tolerance in Arabidopsis. The stch4 mutation reduces CBF protein levels and thus delayed the induction of C-repeat-binding factor (CBF) regulon genes. Ribosomal RNA processing is reduced in stch4 mutants, especially under cold stress. STCH4 associates with multiple ribosomal proteins, and these interactions are modulated by cold stress. These results suggest that the ribosome is a regulatory node for cold stress responses and that STCH4 promotes an altered ribosomal composition and functions in low temperatures to facilitate the translation of proteins important for plant growth and survival under cold stress.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Resposta ao Choque Frio/genética , Biossíntese de Proteínas , Processamento Pós-Transcricional do RNA/genética , RNA Ribossômico/genética , Estresse Fisiológico/genética , Transativadores/metabolismo , Fatores de Transcrição/metabolismo , Proteínas de Arabidopsis/genética , Congelamento , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Mutação/genética , Plantas Geneticamente Modificadas , RNA Ribossômico/metabolismo , Proteínas Ribossômicas/metabolismo , Temperatura , Transativadores/genética
14.
New Phytol ; 226(3): 785-797, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31901205

RESUMO

In Arabidopsis, the plasma membrane transporter PUT3 is important to maintain the cellular homeostasis of polyamines and plays a role in stabilizing mRNAs of some heat-inducible genes. The plasma membrane Na+ /H+ transporter SOS1 and the protein kinase SOS2 are two salt-tolerance determinants crucial for maintaining intracellular Na+ and K+ homeostasis. Here, we report that PUT3 genetically and physically interacts with SOS1 and SOS2, and these interactions modulate PUT3 transport activity. Overexpression of PUT3 (PUT3OE) results in hypersensitivity of the transgenic plants to polyamine and paraquat. The hypersensitivity of PUT3OE is inhibited by the sos1 and sos2 mutations, which indicates that SOS1 and SOS2 are required for PUT3 transport activity. A protein interaction assay revealed that PUT3 physically interacts with SOS1 and SOS2 in yeast and plant cells. SOS2 phosphorylates PUT3 both in vitro and in vivo. SOS1 and SOS2 synergistically activate the polyamine transport activity of PUT3, and PUT3 also modulates SOS1 activity by activating SOS2 in yeast cells. Overall, our findings suggest that both plasma-membrane proteins PUT3 and SOS1 could form a complex with the protein kinase SOS2 in response to stress conditions and modulate the transport activity of each other through protein interactions and phosphorylation.


Assuntos
Proteínas de Arabidopsis , Proteínas Serina-Treonina Quinases , Trocadores de Sódio-Hidrogênio , Antiporters , Arabidopsis , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Membrana Celular/metabolismo , Proteínas de Membrana Transportadoras , Poliaminas , Proteínas Quinases
15.
J Exp Bot ; 71(4): 1598-1613, 2020 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-31745559

RESUMO

Gene regulation is central for growth, development, and adaptation to environmental changes in all living organisms. Many genes are induced by environmental cues, and the expression of these inducible genes is often repressed under normal conditions. Here, we show that the SHINY2 (SHI2) gene is important for repressing salt-inducible genes and also plays a role in cold response. The shi2 mutant displayed hypersensitivity to cold, abscisic acid (ABA), and LiCl. Map-based cloning demonstrates that SHI2 encodes a DEAD- (Asp-Glu-Ala-Asp) box RNA helicase with similarity to a yeast splicing factor. Transcriptomic analysis of the shi2 mutant in response to cold revealed that the shi2 mutation decreased the number of cold-responsive genes and the magnitude of their response, and resulted in the mis-splicing of some cold-responsive genes. Under salt stress, however, the shi2 mutation increased the number of salt-responsive genes but had a negligible effect on mRNA splicing. Our results suggest that SHI2 is a component in a ready-for-transcription repressor complex important for gene repression under normal conditions, and for gene activation and transcription under stress conditions. In addition, SHI2 also serves as a splicing factor required for proper splicing of cold-responsive genes and affects 5' capping and polyadenylation site selection.


Assuntos
RNA Helicases DEAD-box , Regulação da Expressão Gênica de Plantas , Ácido Abscísico , Aclimatação , Temperatura Baixa , RNA Helicases DEAD-box/genética , RNA Helicases DEAD-box/metabolismo , Splicing de RNA/genética
16.
J Lipid Res ; 61(2): 192-204, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31548366

RESUMO

Primitive sterol evolution plays an important role in fossil record interpretation and offers potential therapeutic avenues for human disease resulting from nematode infections. Recognizing that C4-methyl stenol products [8(14)-lophenol] can be synthesized in bacteria while C4-methyl stanol products (dinosterol) can be synthesized in dinoflagellates and preserved as sterane biomarkers in ancient sedimentary rock is key to eukaryotic sterol evolution. In this regard, nematodes have been proposed to convert dietary cholesterol to 8(14)-lophenol by a secondary metabolism pathway that could involve sterol C4 methylation analogous to the C2 methylation of hopanoids (radicle-type mechanism) or C24 methylation of sterols (carbocation-type mechanism). Here, we characterized dichotomous cholesterol metabolic pathways in Caenorhabditis elegans that generate 3-oxo sterol intermediates in separate paths to lophanol (4-methyl stanol) and 8(14)-lophenol (4-methyl stenol). We uncovered alternate C3-sterol oxidation and Δ7 desaturation steps that regulate sterol flux from which branching metabolite networks arise, while lophanol/8(14)-lophenol formation is shown to be dependent on a sterol C4α-methyltransferse (4-SMT) that requires 3-oxo sterol substrates and catalyzes a newly discovered 3-keto-enol tautomerism mechanism linked to S-adenosyl-l-methionine-dependent methylation. Alignment-specific substrate-binding domains similarly conserved in 4-SMT and 24-SMT enzymes, despite minimal amino acid sequence identity, suggests divergence from a common, primordial ancestor in the evolution of methyl sterols. The combination of these results provides evolutionary leads to sterol diversity and points to cryptic C4-methyl steroidogenic pathways of targeted convergence that mediate lineage-specific adaptations.-.


Assuntos
Biocatálise , Caenorhabditis elegans/enzimologia , Metilação , Metiltransferases/metabolismo , Esteróis/biossíntese , Esteróis/química , Animais , Caenorhabditis elegans/crescimento & desenvolvimento
17.
Plant Physiol ; 182(2): 1007-1021, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31776182

RESUMO

Drought is one of the most deleterious environmental conditions affecting crop growth and productivity. Here we report the important roles of a nuclear-encoded chloroplast protein, PsbP Domain Protein 5 (PPD5), in drought resistance in Arabidopsis (Arabidopsis thaliana). From a forward genetic screen, a drought-resistant mutant named ppd5-2 was identified, which has a knockout mutation in PPD5 The ppd5 mutants showed increased H2O2 accumulation in guard cells and enhanced stomatal closure in response to drought stress. Further analysis revealed that the chloroplast-localized PPD5 protein interacts with and is phosphorylated by OST1, and phosphorylation of PPD5 increases its protein stability. Double mutant ppd5-2ost1-3 exhibited phenotypes resembling the ost1-3 single mutant with decreased stomatal closure, increased water loss, reduced H2O2 accumulation in guard cells, and hypersensitivity to drought stress. These results indicate that the chloroplast protein PPD5 negatively regulates drought resistance by modulating guard cell H2O2 accumulation via an OST1-dependent pathway. Interestingly, the thf1-1 mutant defective in the chloroplast protein THF1 displayed drought-resistance and H2O2 accumulation similar to the ppd5 mutants, but the thf1-1ost1-3 double mutant resembled the phenotypes of the thf1-1 single mutant. These results indicate that both OST1-dependent and OST1-independent pathways exist in the regulation of H2O2 production in chloroplasts of guard cells under drought stress conditions. Additionally, our findings suggest a strategy to improve plant drought resistance through manipulation of chloroplast proteins.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas de Cloroplastos/metabolismo , Secas , Proteínas de Membrana/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Proteínas Quinases/metabolismo , Arabidopsis/enzimologia , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica de Plantas/genética , Peróxido de Hidrogênio/metabolismo , Proteínas de Membrana/genética , Mutação , Fosforilação , Complexo de Proteína do Fotossistema II/genética , Estômatos de Plantas/genética , Estômatos de Plantas/metabolismo , Estômatos de Plantas/fisiologia , Plantas Geneticamente Modificadas , Ligação Proteica , Estabilidade Proteica , Transdução de Sinais/genética , Estresse Fisiológico/genética , Água/metabolismo
18.
Plant Cell Environ ; 43(3): 801-817, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31851376

RESUMO

Abiotic stresses greatly affect the immunity of plants. However, it is unknown whether pathogen infection affects abiotic stress tolerance of host plants. Here, the effect of defense response on cold and heat tolerance of host plants was investigated in Pst DC3000-infected Arabidopsis plants, and it was found that the pathogen-induced defense response could alleviate the injury caused by subsequent cold and heat stress (38°C). Transcriptomic sequencing plus RT-qPCR analyses showed that some abiotic stress genes are up-regulated in transcription by pathogen infection, including cold signaling components ICE1, CBF1, and CBF3, and some heat signaling components HSFs and HSPs. Moreover, the pathogen-induced alleviation of cold and heat injury was lost in NahG transgenic line (SA-deficient), sid2-2 and npr1-1 mutant plants, and pathogen-induced expression of cold and heat tolerance-related genes such as CBFs and HSPs, respectively, was lost or compromised in these plants, indicating that salicylic acid signaling pathway is required for the alleviation of cold and heat injury by pathogen infection. In short, our current work showed that in fighting against pathogens, host plants also enhance their cold and heat tolerance via a salicylic acid-dependent pathway.


Assuntos
Arabidopsis/microbiologia , Congelamento , Temperatura Alta , Pseudomonas syringae/fisiologia , Ácido Salicílico/metabolismo , Arabidopsis/citologia , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Sobrevivência Celular , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Interações Hospedeiro-Patógeno , Fenótipo , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Estresse Fisiológico/genética , Transcrição Genética , Transcriptoma/genética
19.
Nat Commun ; 10(1): 3822, 2019 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-31444356

RESUMO

The widespread agricultural problem of pre-harvest sprouting (PHS) could potentially be overcome by improving seed dormancy. Here, we report that miR156, an important grain yield regulator, also controls seed dormancy in rice. We found that mutations in one MIR156 subfamily enhance seed dormancy and suppress PHS with negligible effects on shoot architecture and grain size, whereas mutations in another MIR156 subfamily modify shoot architecture and increase grain size but have minimal effects on seed dormancy. Mechanistically, mir156 mutations enhance seed dormancy by suppressing the gibberellin (GA) pathway through de-represssion of the miR156 target gene Ideal Plant Architecture 1 (IPA1), which directly regulates multiple genes in the GA pathway. These results provide an effective method to suppress PHS without compromising productivity, and will facilitate breeding elite crop varieties with ideal plant architectures.


Assuntos
Giberelinas/metabolismo , MicroRNAs/metabolismo , Oryza/fisiologia , Dormência de Plantas/genética , Proteínas de Plantas/genética , Vias Biossintéticas/genética , Sistemas CRISPR-Cas/genética , Grão Comestível/fisiologia , Regulação da Expressão Gênica de Plantas , MicroRNAs/genética , Mutagênese , Mutação , Melhoramento Vegetal , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas
20.
Plant Cell Environ ; 42(9): 2645-2663, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31087367

RESUMO

Exposure to short-term cold stress influences disease resistance by mechanisms that remain poorly characterized. The molecular basis of cold-activated immunity was therefore investigated in Arabidopsis thaliana inoculated with the bacterial pathogen Pst DC3000, using a transcriptomic analysis. Exposure to cold stress for 10 hr was sufficient to activate immunity, as well as H2 O2 accumulation and callose deposition. Transcriptome changes induced by the 10-hr cold treatment were similar to those caused by pathogen infection, including increased expression of the salicylic acid (SA) pathway marker genes, PR2 and PR5, and genes playing positive roles in defence against (hemi)-biotrophs. In contrast, transcripts encoding jasmonic acid (JA) pathway markers such as PR4 and MYC2 and transcripts with positive roles in defence against necrotrophs were less abundant following the 10-hr cold treatment. Cold-activated immunity was dependent on SA, being partially dependent on NPR1 and ICS1/SID2. In addition, transcripts encoding SA biosynthesis enzymes such as ICS2, PAL1, PAL2, and PAL4 (but not ICS1/SID2) and MES9 were more abundant, whereas GH3.5/WES1 and SOT12 transcripts that encode components involved in SA modification were less abundant following cold stress treatment. These findings show that cold stress cross-activates innate immune responses via a SA-dependent pathway.


Assuntos
Arabidopsis/imunologia , Resposta ao Choque Frio , Resistência à Doença , Ácido Salicílico/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Ciclopentanos/metabolismo , Regulação da Expressão Gênica de Plantas , Glucanos/metabolismo , Peróxido de Hidrogênio/metabolismo , Oxilipinas/metabolismo , Pseudomonas syringae
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