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1.
BMC Plant Biol ; 19(1): 338, 2019 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-31375063

RESUMO

BACKGROUND: In native environments plants frequently experience simultaneous or sequential unfavourable abiotic and biotic stresses. The plant's response to combined stresses is usually not the sum of the individual responses. Here we investigated the impact of cold on plant defense against subsequent herbivory by a generalist and specialist insect. RESULTS: We determined transcriptional responses of Arabidopsis thaliana to low temperature stress (4 °C) and subsequent larval feeding damage by the lepidopteran herbivores Mamestra brassicae (generalist), Pieris brassicae (specialist) or artificial wounding. Furthermore, we compared the performance of larvae feeding upon cold-experienced or untreated plants. Prior experience of cold strongly affected the plant's transcriptional anti-herbivore and wounding response. Feeding by P. brassicae, M. brassicae and artificial wounding induced transcriptional changes of 1975, 1695, and 2239 genes, respectively. Of these, 125, 360, and 681 genes were differentially regulated when cold preceded the tissue damage. Overall, prior experience of cold mostly reduced the transcriptional response of genes to damage. The percentage of damage-responsive genes, which showed attenuated transcriptional regulation when cold preceded the tissue damage, was highest in M. brassicae damaged plants (98%), intermediate in artificially damaged plants (89%), and lowest in P. brassicae damaged plants (69%). Consistently, the generalist M. brassicae performed better on cold-treated than on untreated plants, whereas the performance of the specialist P. brassicae did not differ. CONCLUSIONS: The transcriptional defense response of Arabidopsis leaves to feeding by herbivorous insects and artificial wounding is attenuated by a prior exposure of the plant to cold. This attenuation correlates with improved performance of the generalist herbivore M. brassicae, but not the specialist P. brassicae, a herbivore of the same feeding guild.


Assuntos
Arabidopsis/fisiologia , Herbivoria , Animais , Arabidopsis/metabolismo , Borboletas/fisiologia , Resposta ao Choque Frio , Dieta , Regulação da Expressão Gênica de Plantas/fisiologia , Herbivoria/fisiologia , Larva , Mariposas/fisiologia , Folhas de Planta/metabolismo , Folhas de Planta/fisiologia , Transcriptoma
2.
Dokl Biochem Biophys ; 486(1): 163-167, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31367812

RESUMO

The treatment of Arabidopsis thaliana plants with exogenous cytokinin (CK) followed by heat shock (HS) activated the expression of the genes for the plastid transcription machinery but adversely affected the plant viability. Abscisic acid (ABA), conversely, promoted maintaining the resistance to HS and had differentially affected different components of the plastid transcriptional complex. This hormone suppressed the accumulation of transcripts of PEP genes and the genes encoding PAP proteins, which are involved in DNA-RNA metabolism. However, it had no effect or activated the expression of NEP genes and PAP genes, which are involved in the redox regulation, as well as the genes encoding the stress-inducible trans-factor (SIG5) and the plastid transcription Ser/Thr protein kinase (cpCK2). Thus, for the adaptation of plants to elevated temperatures, both increase and decrease in the expression of the genes for the plastid transcriptional machinery with the involvement of various regulatory systems, including phytohormones, are equally significant.


Assuntos
Ácido Abscísico/farmacologia , Arabidopsis/efeitos dos fármacos , Citocininas/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Resposta ao Choque Térmico/genética , Plastídeos/genética , Transcrição Genética/efeitos dos fármacos , Arabidopsis/citologia , Arabidopsis/genética , Arabidopsis/fisiologia , Resposta ao Choque Térmico/efeitos dos fármacos , Plastídeos/efeitos dos fármacos
3.
J Agric Food Chem ; 67(32): 8905-8918, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31380641

RESUMO

NAC TFs play crucial roles in response to abiotic stresses in plants. Here, ZmNAC071 was identified as a nuclear located transcriptional repressor. Overexpression of ZmNAC071 in Arabidopsis enhanced sensitivity of transgenic plants to ABA and osmotic stress. The expression levels of SODs, PODs, P5CSs, and AtMYB61 were inhibited by ZmNAC071, which results in reduced ROS scavenging and proline content, increased ROS level, and water loss. Besides, the expression levels of some ABA or abiotic stress-related genes, like ABIs, RD29A, DREBs, and LEAs were also significantly inhibited by ZmNAC071. Yeast one-hybrid assay demonstrated that ZmNAC071 specifically bound to the cis-acting elements containing CGT[G/A] core sequences in the promoter of stress-related genes, suggesting that ZmNAC071 may participate in the regulation of transcription of these genes through recognizing the core sequences CGT[G/A]. These results will facilitate further studies concerning the cis-elements and downstream genes targeted by ZmNAC071 in maize.


Assuntos
Arabidopsis/efeitos dos fármacos , Arabidopsis/fisiologia , Ácido Ascórbico/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/fisiologia , Fatores de Transcrição/genética , Zea mays/genética , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação para Baixo/efeitos dos fármacos , Pressão Osmótica , Plantas Geneticamente Modificadas/genética , Espécies Reativas de Oxigênio/metabolismo , Estresse Fisiológico , Fatores de Transcrição/metabolismo
4.
Plant Mol Biol ; 101(1-2): 203-220, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31297725

RESUMO

KEY MESSAGE: Here, a functional characterization of a wheat MSR has been presented: this protein makes a contribution to the plant's tolerance of abiotic stress, acting through its catalytic capacity and its modulation of ROS and ABA pathways. The molecular mechanism and function of certain members of the methionine sulfoxide reductase (MSR) gene family have been defined, however, these analyses have not included the wheat equivalents. The wheat MSR gene TaMSRA4.1 is inducible by salinity and drought stress and in this study, we demonstrate that its activity is restricted to the Met-S-SO enantiomer, and its subcellular localization is in the chloroplast. Furthermore, constitutive expression of TaMSRA4.1 enhanced the salinity and drought tolerance of wheat and Arabidopsis thaliana. In these plants constitutively expressing TaMSRA4.1, the accumulation of reactive oxygen species (ROS) was found to be influenced through the modulation of genes encoding proteins involved in ROS signaling, generation and scavenging, while the level of endogenous abscisic acid (ABA), and the sensitivity of stomatal guard cells to exogenous ABA, was increased. A yeast two-hybrid screen, bimolecular fluorescence complementation and co-immunoprecipitation assays demonstrated that heme oxygenase 1 (HO1) interacted with TaMSRA4.1, and that this interaction depended on a TaHO1 C-terminal domain. In plants subjected to salinity or drought stress, TaMSRA4.1 reversed the oxidation of TaHO1, activating ROS and ABA signaling pathways, but not in the absence of HO1. The aforementioned properties advocate TaMSRA4.1 as a candidate for plant genetic enhancement.


Assuntos
Heme Oxigenase-1/metabolismo , Metionina Sulfóxido Redutases/metabolismo , Transdução de Sinais , Estresse Fisiológico , Triticum/enzimologia , Ácido Abscísico/metabolismo , Arabidopsis/enzimologia , Arabidopsis/genética , Arabidopsis/fisiologia , Secas , Perfilação da Expressão Gênica , Heme Oxigenase-1/genética , Metionina Sulfóxido Redutases/genética , Oxirredução , Reguladores de Crescimento de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Salinidade , Tolerância ao Sal , Plântula/enzimologia , Plântula/genética , Plântula/fisiologia , Triticum/genética , Triticum/fisiologia , Técnicas do Sistema de Duplo-Híbrido
5.
BMC Plant Biol ; 19(1): 320, 2019 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-31319813

RESUMO

BACKGROUND: Plant cell walls participate in all plant-environment interactions. Maintaining cell wall integrity (CWI) during these interactions is essential. This realization led to increased interest in CWI and resulted in knowledge regarding early perception and signalling mechanisms active during CWI maintenance. By contrast, knowledge regarding processes mediating changes in cell wall metabolism upon CWI impairment is very limited. RESULTS: To identify genes involved and to investigate their contributions to the processes we selected 23 genes with altered expression in response to CWI impairment and characterized the impact of T-DNA insertions in these genes on cell wall composition using Fourier-Transform Infrared Spectroscopy (FTIR) in Arabidopsis thaliana seedlings. Insertions in 14 genes led to cell wall phenotypes detectable by FTIR. A detailed analysis of four genes found that their altered expression upon CWI impairment is dependent on THE1 activity, a key component of CWI maintenance. Phenotypic characterizations of insertion lines suggest that the four genes are required for particular aspects of CWI maintenance, cell wall composition or resistance to Plectosphaerella cucumerina infection in adult plants. CONCLUSION: Taken together, the results implicate the genes in responses to CWI impairment, cell wall metabolism and/or pathogen defence, thus identifying new molecular components and processes relevant for CWI maintenance.


Assuntos
Arabidopsis/genética , Parede Celular/metabolismo , Genes de Plantas/fisiologia , Arabidopsis/metabolismo , Arabidopsis/fisiologia , Ascomicetos , Parede Celular/fisiologia , Resistência à Doença/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas/genética , Técnicas de Silenciamento de Genes , Interações Hospedeiro-Patógeno , Doenças das Plantas/imunologia , Plântula/metabolismo , Plântula/fisiologia , Espectroscopia de Infravermelho com Transformada de Fourier
6.
Plant Cell Rep ; 38(9): 1165-1180, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31161264

RESUMO

KEY MESSAGE: Arabidopsis photorespiratory gene AtAGT1 is important for the growth and development of root, the non-photosynthetic organ, and it is involved in a complex metabolic network and salt resistance. AtAGT1 in Arabidopsis encodes an aminotransferase that has a wide range of donor:acceptor combinations, including Asn:glyoxylate. Although it is one of the photorespiratory genes, its encoding protein has been suggested to function also in roots to metabolize Asn. However, experimental data are still lacking. In this study, we investigated experimentally the function of AtAGT1 in roots and our results uncovered its importance in root development during seedling establishment after seed germination. Overexpression of AtAGT1 in roots promoted both the growth of primary root and outgrowth of lateral roots. To further elucidate the molecular mechanisms underlying, amino acid content and gene expression in roots were analyzed, and results revealed that AtAGT1 is involved in a complex metabolic network and salt resistance of roots.


Assuntos
Ácido Abscísico/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Reguladores de Crescimento de Planta/metabolismo , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Expressão Gênica , Germinação , Plantas Geneticamente Modificadas , Tolerância ao Sal , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/fisiologia , Sementes/genética , Sementes/crescimento & desenvolvimento , Sementes/fisiologia , Transaminases/genética , Transaminases/metabolismo
7.
Plant Mol Biol ; 101(1-2): 81-93, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31201686

RESUMO

KEY MESSAGE: Here we show that accumulation of galactose-containing lipids in plastid membranes in shoots and the other membranes in roots maintains Arabidopsis growth under acidic stress and acidic phosphate deficiency. Soil acidification and phosphate deficiency are closely related to each other in natural environments. In addition to the toxicity of high proton concentrations, acid soil can lead to imbalances of ion availability and nutritional deficiencies, including inorganic phosphate (Pi). Among plants, activation of non-phosphorus-containing galactolipid, digalactosyldiacylglycerol (DGDG), synthesis concomitant with phospholipid degradation, namely membrane lipid remodeling, is crucial for coping with Pi starvation. However, regulation mechanisms of membrane lipid composition during acidic stress have not been clarified. Here, we investigated lipid metabolism in Arabidopsis thaliana grown under acidic stress with or without Pi. Under Pi-sufficient acidic conditions, DGDG was increased in shoot membranes, and some Pi starvation-responsive genes that are involved in lipid remodeling were upregulated without reducing Pi content in leaves. In contrast, under acidic Pi deficiency, membrane lipid remodeling in roots was partially repressed at a lower external pH. Nevertheless, phenotypic comparison between wild type and the double mutant of MGD2/3, which are responsible for DGDG accumulation during Pi starvation, indicated that the complete absence of lipid remodeling in roots resulted in a loss of tolerance to Pi deficiency rather specifically under acidic conditions. This result suggested important physiological roles of galactolipid-enriched membranes under acidic Pi deficiency.


Assuntos
Arabidopsis/fisiologia , Galactolipídeos/metabolismo , Metabolismo dos Lipídeos , Lipídeos de Membrana/metabolismo , Fosfatos/deficiência , Fosfolipídeos/metabolismo , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Concentração de Íons de Hidrogênio , Fenótipo , Folhas de Planta/genética , Folhas de Planta/fisiologia , Raízes de Plantas/genética , Raízes de Plantas/fisiologia , Brotos de Planta/genética , Brotos de Planta/fisiologia , Plastídeos/metabolismo , Estresse Fisiológico
8.
Plant Physiol Biochem ; 141: 300-305, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31202194

RESUMO

MYB-type transcription factors are known to participate in the response of plants to a number of stress agents. MsMYB2L is an alfalfa member of this large gene family. Its transcription in alfalfa seedlings was found to be rapidly and strongly induced by salinity, moisture deficiency and exogenously supplied abscisic acid. An analysis based on a yeast one hybrid assay indicated that its product is able to activate transcription, consistent with its function as a transcription factor. When the gene was constitutively expressed in Arabidopsis thaliana, both germination and seedling growth were more sensitive to ABA treatment than wild type, and growth was less strongly compromised by salinity and moisture deficiency stress, presumably as a result of the induction of certain stress-related genes active in ABA-dependent pathways. The transgenic seedlings' enhanced the synthesis of many osmotic regulatory substances such as proline and soluble sugar, and decreased the lipid peroxidation. In all, MsMYB2L represents a potential candidate gene for manipulating the salinity and drought tolerance of alfalfa.


Assuntos
Ácido Abscísico/metabolismo , Arabidopsis/fisiologia , Proteínas de Ligação a DNA/genética , Secas , Medicago sativa/genética , Proteínas de Plantas/genética , Salinidade , Fatores de Transcrição/genética , Regulação da Expressão Gênica de Plantas , Técnicas Genéticas , Germinação , Filogenia , Plantas Geneticamente Modificadas/fisiologia , Polietilenoglicóis/química , Plântula/fisiologia , Estresse Fisiológico , Açúcares/química , Transcrição Genética , Ativação Transcricional
9.
Plant Physiol Biochem ; 141: 343-352, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31207495

RESUMO

Plant U-box (PUB) E3 ubiquitin ligases play crucial roles in the plant response to abiotic stress and the phytohormone abscisic acid (ABA) signaling, but little is known about them in bryophytes. Here, a representative U-box armadillo repeat (PUB-ARM) ubiquitin E3 ligase from Antarctic moss Pohlia nutans (PnSAG1), was explored for its role in abiotic stress response in Arabidopsis thaliana and Physcomitrella patens. The expression of PnSAG1 was rapidly induced by exogenous abscisic acid (ABA), salt, cold and drought stresses. PnSAG1 was localized to the cytoplasm and showed E3 ubiquitin ligase activity by in vitro ubiquitination assay. The PnSAG1-overexpressing Arabidopsis enhanced the sensitivity with respect to ABA and salt stress during seed germination and early root growth. Similarly, heterogeneous overexpression of PnSAG1 in P. patens was more sensitive to the salinity and ABA in their gametophyte growth. The analysis by RT-qPCR revealed that the expression of salt stress/ABA-related genes were downregulated in PnSAG1-overexpressing plants after salt treatment. Taken together, our results indicated that PnSAG1 plays a negative role in plant response to ABA and salt stress.


Assuntos
Ácido Abscísico/farmacologia , Arabidopsis/fisiologia , Briófitas/enzimologia , Bryopsida/fisiologia , Estresse Salino , Ubiquitina-Proteína Ligases/genética , Regiões Antárticas , Arabidopsis/genética , Briófitas/genética , Bryopsida/genética , Biologia Computacional , Secas , Regulação da Expressão Gênica de Plantas , Células Germinativas Vegetais/metabolismo , Germinação , Raízes de Plantas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/fisiologia , Transdução de Sinais
10.
Plant Physiol Biochem ; 141: 446-455, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31247427

RESUMO

Coumarin plays a pivotal role in plant response to biotic stress, as well as in the mediation of nutrient acquisition. However, its functions in response to abiotic stresses are largely unknown. In this work, a homologous gene, GmF6'H1, of AtF6'H1, which encodes the enzyme catalyzing the final rate-limiting step in the biosynthesis pathway of coumarin, was isolated from soybean. GmF6'H1 protein shares very high amino acid identity with AtF6'H1, and expression of GmF6'H1 in atf6'h1 can successfully restore the decreased coumarin production in the T-DNA insertion mutant. Further study revealed that the expression of GmF6'H1 in soybean was remarkably induced by salt stress. Constitutive expression of GmF6'H1 in Arabidopsis, driven by 35S promoter, significantly enhanced the resistance to salt of transgenic Arabidopsis. All these results suggest that GmF6'H1 can be used as a potential candidate gene for the engineering of plants with improved resistance to both biotic and abiotic stresses.


Assuntos
Arabidopsis/fisiologia , Regulação da Expressão Gênica de Plantas , Tolerância ao Sal , Soja/enzimologia , Arabidopsis/genética , Clorofila/química , Clonagem Molecular , Cumarínicos/química , Perfilação da Expressão Gênica , Germinação , Fenótipo , Folhas de Planta/metabolismo , Plantas Geneticamente Modificadas/fisiologia , Regiões Promotoras Genéticas , Soja/genética
11.
Nat Commun ; 10(1): 2630, 2019 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-31201314

RESUMO

Phytochromes initiate chloroplast biogenesis by activating genes encoding the photosynthetic apparatus, including photosynthesis-associated plastid-encoded genes (PhAPGs). PhAPGs are transcribed by a bacterial-type RNA polymerase (PEP), but how phytochromes in the nucleus activate chloroplast gene expression remains enigmatic. We report here a forward genetic screen in Arabidopsis that identified NUCLEAR CONTROL OF PEP ACTIVITY (NCP) as a necessary component of phytochrome signaling for PhAPG activation. NCP is dual-targeted to plastids and the nucleus. While nuclear NCP mediates the degradation of two repressors of chloroplast biogenesis, PIF1 and PIF3, NCP in plastids promotes the assembly of the PEP complex for PhAPG transcription. NCP and its paralog RCB are non-catalytic thioredoxin-like proteins that diverged in seed plants to adopt nonredundant functions in phytochrome signaling. These results support a model in which phytochromes control PhAPG expression through light-dependent double nuclear and plastidial switches that are linked by evolutionarily conserved and dual-localized regulatory proteins.


Assuntos
Proteínas de Arabidopsis/metabolismo , Cloroplastos/metabolismo , Chaperonas Moleculares/metabolismo , Fitocromo/metabolismo , Transcrição Genética/fisiologia , Arabidopsis/fisiologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Núcleo Celular/genética , Núcleo Celular/metabolismo , Cloroplastos/genética , RNA Polimerases Dirigidas por DNA/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Luz , Fotossíntese/fisiologia , Plantas Geneticamente Modificadas , Plastídeos/genética , Plastídeos/metabolismo , Transdução de Sinais/fisiologia , Transcrição Genética/efeitos da radiação
12.
Nat Commun ; 10(1): 2659, 2019 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-31201323

RESUMO

In contrast to the plasma membrane, the vacuole membrane has not yet been associated with electrical excitation of plants. Here, we show that mesophyll vacuoles from Arabidopsis sense and control the membrane potential essentially via the K+-permeable TPC1 and TPK channels. Electrical stimuli elicit transient depolarization of the vacuole membrane that can last for seconds. Electrical excitability is suppressed by increased vacuolar Ca2+ levels. In comparison to wild type, vacuoles from the fou2 mutant, harboring TPC1 channels insensitive to luminal Ca2+, can be excited fully by even weak electrical stimuli. The TPC1-loss-of-function mutant tpc1-2 does not respond to electrical stimulation at all, and the loss of TPK1/TPK3-mediated K+ transport affects the duration of TPC1-dependent membrane depolarization. In combination with mathematical modeling, these results show that the vacuolar K+-conducting TPC1 and TPK1/TPK3 channels act in concert to provide for Ca2+- and voltage-induced electrical excitability to the central organelle of plant cells.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Canais de Cálcio/metabolismo , Potenciais da Membrana/fisiologia , Vacúolos/fisiologia , Proteínas de Arabidopsis/genética , Canais de Cálcio/genética , Sinalização do Cálcio/fisiologia , Membranas Intracelulares/fisiologia , Mutação com Perda de Função , Células do Mesofilo/citologia , Células do Mesofilo/fisiologia , Plantas Geneticamente Modificadas , Potássio/metabolismo , Canais de Potássio/metabolismo , Canais de Potássio de Domínios Poros em Tandem/metabolismo
13.
Nat Commun ; 10(1): 2629, 2019 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-31201355

RESUMO

Light initiates chloroplast biogenesis by activating photosynthesis-associated genes encoded by not only the nuclear but also the plastidial genome, but how photoreceptors control plastidial gene expression remains enigmatic. Here we show that the photoactivation of phytochromes triggers the expression of photosynthesis-associated plastid-encoded genes (PhAPGs) by stimulating the assembly of the bacterial-type plastidial RNA polymerase (PEP) into a 1000-kDa complex. Using forward genetic approaches, we identified REGULATOR OF CHLOROPLAST BIOGENESIS (RCB) as a dual-targeted nuclear/plastidial phytochrome signaling component required for PEP assembly. Surprisingly, RCB controls PhAPG expression primarily from the nucleus by interacting with phytochromes and promoting their localization to photobodies for the degradation of the transcriptional regulators PIF1 and PIF3. RCB-dependent PIF degradation in the nucleus signals the plastids for PEP assembly and PhAPG expression. Thus, our findings reveal the framework of a nucleus-to-plastid anterograde signaling pathway by which phytochrome signaling in the nucleus controls plastidial transcription.


Assuntos
Proteínas de Arabidopsis/metabolismo , Cloroplastos/metabolismo , RNA Polimerases Dirigidas por DNA/metabolismo , Fitocromo/metabolismo , Tiorredoxinas/metabolismo , Transcrição Genética/fisiologia , Arabidopsis/fisiologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Núcleo Celular/metabolismo , Cloroplastos/genética , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Luz , Fotossíntese/fisiologia , Plantas Geneticamente Modificadas , Plastídeos/genética , Plastídeos/metabolismo , Proteólise , Transdução de Sinais/fisiologia , Transcrição Genética/efeitos da radiação
14.
Plant Sci ; 285: 200-213, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31203885

RESUMO

NONRACE-SPECIFIC DISEASE RESISTANCE (NDR1) is a widely characterized gene that plays a key role in defense against multiple bacterial, fungal, oomycete and nematode plant pathogens. NDR1 is required for activation of resistance by multiple NB and LRR-containing (NLR) protein immune sensors and contributes to basal defense. The role of NDR1 in positively regulating salicylic acid (SA)-mediated plant defense responses is well documented. However, ndr1-1 plants flower earlier and show accelerated development in comparison to wild type (WT) Arabidopsis plants, indicating that NDR1 is a negative regulator of flowering and growth. Exogenous application of gibberellic acid (GA) further accelerates the early flowering phenotype in ndr1-1 plants, while the GA biosynthesis inhibitor paclobutrazol attenuated the early flowering phenotype of ndr1-1, but not to WT levels, suggesting partial resistance to paclobutrazol and enhanced GA response in ndr1-1 plants. Mass spectroscopy analyses confirmed that ndr1-1 plants have 30-40% higher levels of GA3 and GA4, while expression of various GA metabolic genes and major flowering regulatory genes is also altered in the ndr1-1 mutant. Taken together this study provides evidence of crosstalk between the ndr1-1-mediated defense and GA-regulated developmental programs in plants.


Assuntos
Arabidopsis/genética , Flores/crescimento & desenvolvimento , Giberelinas/fisiologia , Reguladores de Crescimento de Planta/fisiologia , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/fisiologia , Proteínas de Arabidopsis/fisiologia , Resistência à Doença/genética , Resistência à Doença/fisiologia , Giberelinas/metabolismo , Mutação/genética , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Reguladores de Crescimento de Planta/metabolismo , Ácido Salicílico/metabolismo , Fatores de Transcrição/fisiologia , Transcriptoma , Verticillium
15.
Plant Sci ; 285: 34-43, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31203892

RESUMO

Seed germination is a critical stage during the initiation of the plant lifecycle and is strongly affected by endogenous phytohormones and environmental stress. High temperature (HT) upregulates endogenous abscisic acid (ABA) to suppress seed germination, and ABA-INSENSITIVE 5 (ABI5) is the key positive regulator in the ABA signal-mediated modulation of seed germination. In plants, hydrogen sulfide (H2S) is a small gas messenger that participates in multiple physiological processes, but its role in seed germination thermotolerance has not been thoroughly elucidated to date. In this study, we found that H2S enhanced the seed germination rate under HT. Moreover, HT accelerates the efflux of the E3 ligase CONSTITUTIVE PHOTOMORPHOGENESIS 1 (COP1) from the nucleus to the cytoplasm, which results in increased nuclear accumulation of ELONG HYPCOTYL 5 (HY5) to activate the expression of ABI5 and thereby suppress seed germination. However, the H2S signal reversed the HT effect, as characterized by increased COP1 in the nucleus, which resulted in increased degradation of HY5 and reduced expression of ABI5 and thereby enhanced the seed germination thermotolerance. Thus, our findings reveal a novel role for the H2S signal in the modulation of seed germination thermotolerance through the nucleocytoplasmic partitioning of COP1 and the downstream HY5 and ABI5 pathways.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Germinação/fisiologia , Sulfeto de Hidrogênio/metabolismo , Proteínas Nucleares/metabolismo , Sementes/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Ácido Abscísico/metabolismo , Ácido Abscísico/fisiologia , Arabidopsis/fisiologia , Proteínas de Arabidopsis/fisiologia , Fatores de Transcrição de Zíper de Leucina Básica/fisiologia , Núcleo Celular/enzimologia , Núcleo Celular/metabolismo , Giberelinas/metabolismo , Giberelinas/fisiologia , Temperatura Alta , Proteínas Nucleares/fisiologia , Reguladores de Crescimento de Planta/fisiologia , Plantas Geneticamente Modificadas , Reação em Cadeia da Polimerase em Tempo Real , Sementes/fisiologia , Transdução de Sinais/fisiologia , Termotolerância , Ubiquitina-Proteína Ligases/fisiologia
16.
Plant Sci ; 285: 44-54, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31203893

RESUMO

Although the involvement of ROS (reactive oxygen species) in leaf senescence is well known, the factors governing this accumulation of ROS are not fully characterized. In this study, analysis of transgenic overexpressing and knock out lines of AtWDS1 (encoding a WD repeat protein), indicates that AtWDS1 negatively regulates age-dependent and dark-induced leaf senescence. Furthermore, we observed ROS accumulation and altered tolerance of oxidative stress in atwds1 plants, as well as upregulated expression of oxidative stress-responsive genes. The location of an EGFP-AtWDS1 fusion protein in the nucleus of transformed cells and plants indicates that AtWDS1 is a nuclear protein, and, using a Dual-Luciferase assay, we showed that AtWDS1 can act as a transcription activator. However, the lack of a nuclear localization sequence in AtWDS1 suggests that its presence in the nucleus must depend on interactions with other proteins. Indeed, we found that AtWDS1 interacts directly with AtRanBPM, and that mutation of the AtRanBPM gene results in partial mislocalization of AtWDS1 in the cytoplasm. Together, these results suggest a role for AtWDS1 as a novel modulator of redox homeostasis, which responds to developmental and stress signals to regulate leaf senescence.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/crescimento & desenvolvimento , Folhas de Planta/crescimento & desenvolvimento , Arabidopsis/fisiologia , Clorofila/metabolismo , Escuridão , Microscopia Confocal , Folhas de Planta/fisiologia , Protoplastos/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Transcriptoma
17.
Plant Sci ; 285: 55-67, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31203894

RESUMO

C2H2-type zinc finger proteins play important roles in plant growth, development, and abiotic stress tolerance. Here, we explored the role of the C2H2-type zinc finger protein SALT INDUCED ZINC FINGER PROTEIN1 (AtSIZ1; At3G25910) in Arabidopsis thaliana under salt stress. AtSIZ1 expression was induced by salt treatment. During the germination stage, the germination rate, germination energy, germination index, cotyledon growth rate, and root length were significantly higher in AtSIZ1 overexpression lines than in the wild type under various stress treatments, whereas these indices were significantly reduced in AtSIZ1 loss-of-function mutants. At the mature seedling stage, the overexpression lines maintained higher levels of K+, proline, and soluble sugar, lower levels of Na+ and MDA, and lower Na+/K+ ratios than the wild type. Stress-related marker genes such as SOS1, AtP5CS1, AtGSTU5, COR15A, RD29A, and RD29B were expressed at higher levels in the overexpression lines than the wild type and loss-of-function mutants under salt treatment. These results indicate that AtSIZ1 improves salt tolerance in Arabidopsis by helping plants maintain ionic homeostasis and osmotic balance.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/metabolismo , Ligases/fisiologia , Dedos de Zinco/fisiologia , Arabidopsis/genética , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Homeostase , Ligases/genética , Filogenia , Potássio/metabolismo , Prolina/metabolismo , Estresse Salino , Tolerância ao Sal , Sódio/metabolismo , Dedos de Zinco/genética
18.
Plant Sci ; 285: 99-109, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31203898

RESUMO

Seed development is a complex regulatory process that includes a transition from gametophytic to sporophytic program. The synchronized development of different seed compartments (seed coat, endosperm and embryo) depends on a balance in parental genome contributions. In the most severe cases, the disruption of the balance leads to seed abortion. This represents one of the main obstacles for the engineering of asexual reproduction through seeds (apomixis), and for generating new interspecies hybrids. The repression of auxin synthesis by the Polycomb Repressive Complex 2 (PRC2) is a major mechanism contributing to sensing genome balance. However, current efforts focusing on decreasing PRC2 or elevating auxin levels have not yet resulted in the production of apomictic seed. Here, we show that EMSY-Like Tudor/Agenet H3K36me3 histone readers EML1 and EML3 are necessary for early stages of seed development to proceed at a normal rate in Arabidopsis. We further demonstrate that both EML1 and EML3 are required to prevent the initiation of seed development in the absence of fertilization. Based on the whole genome expression analysis, we identify auxin transport and signaling genes as the most enriched downstream targets of EML1 and EML3. We hypothesize that EML1 and EML3 function to repress and soften paternal gene expression by fine-tuning auxin responses. Discovery of this pathway may contribute to the engineering of apomixis and interspecies hybrids.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/crescimento & desenvolvimento , Histonas/metabolismo , Sementes/crescimento & desenvolvimento , Apomixia , Arabidopsis/genética , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Fertilização , Filogenia , Plantas Geneticamente Modificadas , Reação em Cadeia da Polimerase , Sementes/fisiologia
19.
Plant Sci ; 284: 177-184, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31084870

RESUMO

Both nitrogen (N) and nitric oxide (NO) postpone plant flowering. However, we still don't know whether N and NO trigger the same signaling pathways leading to flowering delay. Our previous study found that ferredoxin NADP+ oxidoreductase (FNR1) and the blue-light receptor cryptochrome 1 (CRY1) are involved in nitrogen-regulated flowering-time control. However, NO-induced late-flowering does not require FNR1 or CRY1. Sucrose supply counteracts the flowering delay induced by NO. However high-N-induced late-flowering could not be reversed by 5% sucrose supplementation. The high nitrogen condition decreased the amplitudes of all transcripts of the circadian clock. While NO increased the amplitudes of circadian transcripts of CRY1, LHY (LATE ELONGATED HYPOCOTYL), CCA1 (CIRCADIAN CLOCK ASSOCIATED 1) and TOC1 (TIMING OF CAB EXPRESSION 1), but decreased the amplitudes of circadian transcripts of CO (CONSTANS) and GI (GIGANTEA). 5% sucrose supplementation reversed the declines in amplitudes of circadian transcripts of CO and GI after the NO treatment. NO induced S-nitrosation modification on oscillators CO and GI, but not on the other oscillators of the circadian clock. Sucrose supply interestingly reduced S-nitrosation levels of GI and CO proteins. Thus N and NO rely on overlapping but distinct signaling pathways on plant flowering.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Flores/crescimento & desenvolvimento , Óxido Nítrico/fisiologia , Nitrogênio/metabolismo , Arabidopsis/fisiologia , Regulação da Expressão Gênica de Plantas , Óxido Nítrico/metabolismo , Nitrogênio/fisiologia , Reação em Cadeia da Polimerase em Tempo Real , Transdução de Sinais , Sacarose/metabolismo
20.
Plant Sci ; 284: 185-191, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31084871

RESUMO

Transcriptional activation of ascorbate biosynthesis-associated genes under illumination is one of the important steps in ascorbate pool size regulation in photosynthetic tissues. Several biological processes within chloroplasts such as photosynthesis are required for this activation, suggesting functional chloroplasts to play a key role. We herein found that when grown on agar plate, ascorbate content in Arabidopsis non-photosynthetic tissues, roots, are unexpectedly almost comparable to that in shoots. The high accumulation of ascorbate was particularly observed in root regions closer to the root-hypocotyl junction, in which chloroplast development occurred because of a direct exposure to light. When chloroplast development in roots were further stimulated by shoot removal, the expression of biosynthetic genes, especially VTC2 gene that encodes GDP-l-galactose phosphorylase, was activated, resulting in an increase in ascorbate pool size. These positive effects were canceled when the roots were treated with a photosynthetic inhibitor. A null mutation in the LONG HYPOCOTYL 5 (HY5) gene almost completely inhibited root greening as well as the VTC2 expression. Overall, these findings show that chloroplast development can trigger the expression of ascorbate biosynthesis-associated genes not only in leaves but also in roots.


Assuntos
Arabidopsis/metabolismo , Ácido Ascórbico/biossíntese , Cloroplastos/fisiologia , Raízes de Plantas/metabolismo , Arabidopsis/fisiologia , Ácido Ascórbico/metabolismo , Clorofila/metabolismo , Cloroplastos/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas/fisiologia , Redes e Vias Metabólicas , Raízes de Plantas/fisiologia , Reação em Cadeia da Polimerase em Tempo Real
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