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1.
Physiol Plant ; 169(3): 452-466, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32412656

RESUMO

Under photoperiodic conditions, Arabidopsis thaliana seedling growth is inhibited in long days (LDs), but promoted under the extended nights of short days (SDs). This behavior is partly implemented by phytochrome (phy)-imposed oscillations in the abundance of the growth-promoting, phy-interacting bHLH transcription factors PHY-INTERACTING FACTOR 1 (PIF1), PIF3, PIF4 and PIF5 (PIF quartet or PIFq). However, the observation that a pifq mutant is still stimulated to elongate when given a phy-inactivating end-of-day far-red pulse (EODFR), suggests that additional factors are involved in the phy-mediated suppression of growth during the subsequent dark period. Here, by combining growth-analysis of pif7 single- and higher-order mutants with gene expression analysis under SD, LD, SD-EODFR, and LD-EODFR, we show that PIF7 promotes growth during the dark hours of SD, by regulating growth-related gene expression. Interestingly, the relative contribution of PIF7 in promoting growth is stronger under EODFR, whereas PIF3 role is more important under SD, suggesting that PIF7 is a prominent target of phy-suppression. Indeed, we show that phy imposes phosphorylation and inactivation of PIF7 during the light hours in SD, and prevents full dephosphorylation during the night. This repression can be lifted with an EODFR, which correlates with increased PIF7-mediated gene expression and elongation. In addition, our results suggest that PIF7 function might involve heterodimerization with PIF3. Furthermore, our data indicate that a pifqpif7 quintuple mutant is largely insensitive to photoperiod for hypocotyl elongation. Collectively, the data suggest that PIF7, together with the PIFq, is required for the photoperiodic regulation of seasonal growth.


Assuntos
Proteínas de Arabidopsis , Arabidopsis/genética , Proteínas de Ligação a DNA , Fitocromo/genética , Proteínas de Arabidopsis/fisiologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Proteínas de Ligação a DNA/fisiologia , Regulação da Expressão Gênica de Plantas , Hipocótilo/genética , Luz , Fotoperíodo
2.
Nat Commun ; 11(1): 2114, 2020 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-32355217

RESUMO

Most plants associate with beneficial arbuscular mycorrhizal (AM) fungi that facilitate soil nutrient acquisition. Prior to contact, partner recognition triggers reciprocal genetic remodelling to enable colonisation. The plant Dwarf14-Like (D14L) receptor conditions pre-symbiotic perception of AM fungi, and also detects the smoke constituent karrikin. D14L-dependent signalling mechanisms, underpinning AM symbiosis are unknown. Here, we present the identification of a negative regulator from rice, which operates downstream of the D14L receptor, corresponding to the homologue of the Arabidopsis thaliana Suppressor of MAX2-1 (AtSMAX1) that functions in karrikin signalling. We demonstrate that rice SMAX1 is a suppressor of AM symbiosis, negatively regulating fungal colonisation and transcription of crucial signalling components and conserved symbiosis genes. Similarly, rice SMAX1 negatively controls strigolactone biosynthesis, demonstrating an unexpected crosstalk between the strigolactone and karrikin signalling pathways. We conclude that removal of SMAX1, resulting from D14L signalling activation, de-represses essential symbiotic programmes and increases strigolactone hormone production.


Assuntos
Proteínas de Arabidopsis/fisiologia , Peptídeos e Proteínas de Sinalização Intracelular/fisiologia , Micorrizas/fisiologia , Oryza/microbiologia , Proteínas de Plantas/fisiologia , Simbiose , Arabidopsis/genética , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Furanos/metabolismo , Regulação da Expressão Gênica de Plantas , Germinação , Compostos Heterocíclicos com 3 Anéis/metabolismo , Homozigoto , Peptídeos e Proteínas de Sinalização Intracelular/genética , Lactonas/metabolismo , Família Multigênica , Oryza/genética , Filogenia , Proteínas de Plantas/genética , Raízes de Plantas/microbiologia , Piranos/metabolismo , RNA-Seq , Transdução de Sinais
3.
Physiol Plant ; 169(3): 418-429, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32248530

RESUMO

Arabidopsis CONSTITUTIVE PHOTOMORPHOGENIC1/SUPPRESSOR OF PHYA-105 (COP1/SPA) is an E3 ubiquitin ligase complex that prevents photomorphogenesis in darkness by ubiquitinating and subsequently degrading light-responsive transcription factors. Upon light perception, photoreceptors directly interact with the COP1/SPA complex to suppress its activity. In blue light (450-500 nm of visible spectrum), COP1/SPA activity is inhibited by the cryptochrome photoreceptors (CRY1 and CRY2), FKF1 from the ZEITLUPE family as well as phytochrome A. Together, these photoreceptors regulate vital aspects of plant growth and development from seedling stage to the induction of flowering. This review presents and discusses the recent advances in blue light-mediated suppression of COP1/SPA activity.


Assuntos
Proteínas de Arabidopsis , Arabidopsis/genética , Ubiquitina-Proteína Ligases , Proteínas de Arabidopsis/fisiologia , Regulação da Expressão Gênica de Plantas , Luz , Ubiquitina-Proteína Ligases/fisiologia
4.
J Plant Res ; 133(3): 409-417, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32227262

RESUMO

To fine tune defense response output, plants recruit both positive and negative regulators. Here we report Arabidopsis DORMANCY/AUXIN ASSOCIATED FAMILY PROTEIN 2(DAP2) gene as a negative regulator of basal defense against virulent bacterial pathogens. Expression of DAP2 enhances upon pathogen inoculation. Our experiments show that DAP2 suppressed resistance against virulent strains of bacterial pathogens, pathogen-induced callose deposition, and ROS accumulation; however, it did not influence effector-triggered immunity. In addition, DAP2 negatively regulated systemic acquired resistance (SAR). DAP2 expression was enhanced in the pathogen-free systemic tissues of SAR-induced plants. Previously, Arabidopsis Flowering locus D (FLD) gene has been shown to be essential for SAR but not for local resistance. We show here that FLD function is necessary for SAR-induced expression of DAP2, suggesting DAP2 as a target of FLD for activation of SAR in Arabidopsis.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/fisiologia , Resistência à Doença , Doenças das Plantas/microbiologia , Arabidopsis/microbiologia , Regulação da Expressão Gênica de Plantas
5.
Plant Mol Biol ; 103(1-2): 197-210, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32130643

RESUMO

DEEPER ROOTING 1 (DRO1) contributes to the downward gravitropic growth trajectory of roots upstream of lateral auxin transport in monocots and dicots. Loss of DRO1 function leads to horizontally oriented lateral roots and altered gravitropic set point angle, while loss of all three DRO family members results in upward, vertical root growth. Here, we attempt to dissect the roles of AtDRO1 by analyzing expression, protein localization, auxin gradient formation, and auxin responsiveness in the atdro1 mutant. Current evidence suggests AtDRO1 is predominantly a membrane-localized protein. Here we show that VENUS-tagged AtDRO1 driven by the native AtDRO1 promoter complemented an atdro1 Arabidopsis mutant and the protein was localized in root tips and detectable in nuclei. atdro1 primary and lateral roots showed impairment in establishing an auxin gradient upon gravistimulation as visualized with DII-VENUS, a sensor for auxin signaling and proxy for relative auxin distribution. Additionally, PIN3 domain localization was not significantly altered upon gravistimulation in atdro1 primary and lateral roots. RNA-sequencing revealed differential expression of known root development-related genes in atdro1 mutants. atdro1 lateral roots were able to respond to exogenous auxin and AtDRO1 gene expression levels in root tips were unaffected by the addition of auxin. Collectively, the data suggest that nuclear localization may be important for AtDRO1 function and suggests a more nuanced role for DRO1 in regulating auxin-mediated changes in lateral branch angle. KEY MESSAGE: DEEPER ROOTING 1 (DRO1) when expressed from its native promoter is predominately localized in Arabidopsis root tips, detectable in nuclei, and impacts auxin gradient formation.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Ácidos Indolacéticos/metabolismo , Proteínas Nucleares/fisiologia , Raízes de Plantas/metabolismo , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/fisiologia , Núcleo Celular/metabolismo , Teste de Complementação Genética , Gravitação , Mutação , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo
6.
Proc Natl Acad Sci U S A ; 117(13): 7482-7493, 2020 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-32170020

RESUMO

Plants balance their competing requirements for growth and stress tolerance via a sophisticated regulatory circuitry that controls responses to the external environments. We have identified a plant-specific gene, COST1 (constitutively stressed 1), that is required for normal plant growth but negatively regulates drought resistance by influencing the autophagy pathway. An Arabidopsis thaliana cost1 mutant has decreased growth and increased drought tolerance, together with constitutive autophagy and increased expression of drought-response genes, while overexpression of COST1 confers drought hypersensitivity and reduced autophagy. The COST1 protein is degraded upon plant dehydration, and this degradation is reduced upon treatment with inhibitors of the 26S proteasome or autophagy pathways. The drought resistance of a cost1 mutant is dependent on an active autophagy pathway, but independent of other known drought signaling pathways, indicating that COST1 acts through regulation of autophagy. In addition, COST1 colocalizes to autophagosomes with the autophagosome marker ATG8e and the autophagy adaptor NBR1, and affects the level of ATG8e protein through physical interaction with ATG8e, indicating a pivotal role in direct regulation of autophagy. We propose a model in which COST1 represses autophagy under optimal conditions, thus allowing plant growth. Under drought, COST1 is degraded, enabling activation of autophagy and suppression of growth to enhance drought tolerance. Our research places COST1 as an important regulator controlling the balance between growth and stress responses via the direct regulation of autophagy.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/fisiologia , Estresse Fisiológico/fisiologia , Arabidopsis/citologia , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Autofagossomos/metabolismo , Autofagia/fisiologia , Família da Proteína 8 Relacionada à Autofagia/metabolismo , Proteínas de Transporte/metabolismo , Secas , Genes de Plantas , Transdução de Sinais , Estresse Fisiológico/genética
7.
J Plant Res ; 133(3): 393-407, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32200466

RESUMO

Hydrogen sulfide (H2S) is an important gaseous molecule responding to osmotic stress in plant. Phospholipase Dα1 (PLDα1) and reactive oxygen species (ROS) are involved in many biotic or abiotic stress responses. Using the seedlings of Arabidopsis thaliana ecotype (WT), PLDα1 deficient mutant (pldα1) and the L-cysteine desulfhydrase (L-DEs) deficient mutant (lcd) as materials, the effect of H2S responding to osmotic stress and the functions of PLDα1 and ROS in this response were investigated. The results showed that H2S, PLDα1 and ROS were involved in osmotic stress resistance. Exogenous sodium hydrosulfide (NaHS) promoted the endogenous H2S content and up-regulated the expression of LCD in WT, lcd and plda1. Exogenous phosphatidic acid (PA) enhanced the H2S content and up-regulated the expressions of LCD in WT and plda1 but had no significant effect on the H2S content and LCD expression in lcd under osmotic stress. This suggested that H2S was located downstream of PLDα1 to participate in the osmotic stress signal response. Exogenous NaHS treatment regulated the antioxidant enzymes (SOD, POD, and CAT). The activities and the gene relative expressions of antioxidant enzymes in pldα1 and lcd were higher than those in WT under osmotic stress. This indicated that H2S and PLD regulated the antioxidant enzyme system under osmotic stress. The ROS level, electrolyte leakage (EL), malondialdehyde (MDA) were decreased by NaHS under osmotic stress, demonstrating H2S maintained the membrane integrity. All of these results revealed that H2S alleviated the osmotic stress by elevating PLD and suppressing ROS in A. thaliana.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/fisiologia , Sulfeto de Hidrogênio/metabolismo , Pressão Osmótica , Fosfolipase D/fisiologia , Espécies Reativas de Oxigênio/metabolismo
8.
Science ; 367(6479): 763-768, 2020 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-32054757

RESUMO

Effector-triggered immunity (ETI), induced by host immune receptors in response to microbial effectors, protects plants against virulent pathogens. However, a systematic study of ETI prevalence against species-wide pathogen diversity is lacking. We constructed the Pseudomonas syringae Type III Effector Compendium (PsyTEC) to reduce the pan-genome complexity of 5127 unique effector proteins, distributed among 70 families from 494 strains, to 529 representative alleles. We screened PsyTEC on the model plant Arabidopsis thaliana and identified 59 ETI-eliciting alleles (11.2%) from 19 families (27.1%), with orthologs distributed among 96.8% of P. syringae strains. We also identified two previously undescribed host immune receptors, including CAR1, which recognizes the conserved effectors AvrE and HopAA1, and found that 94.7% of strains harbor alleles predicted to be recognized by either CAR1 or ZAR1.


Assuntos
Arabidopsis/imunologia , Arabidopsis/microbiologia , Interações Hospedeiro-Patógeno/imunologia , Imunidade Inata/genética , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Imunidade Vegetal/genética , Pseudomonas syringae/patogenicidade , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/fisiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/imunologia , Proteínas de Transporte/genética , Proteínas de Transporte/fisiologia , Genoma de Planta , Interações Hospedeiro-Patógeno/genética , Doenças das Plantas/genética , Pseudomonas syringae/genética
9.
J Plant Res ; 133(2): 245-256, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32048094

RESUMO

Abscisic acid (ABA) response element (ABRE)-binding factors (ABFs) are basic region/leucine zipper motif (bZIP) transcription factors that regulate the expression of ABA-induced genes containing ABRE in their promoters. The amino acid sequence of the wheat bZIP protein, TaABI5, showed high homology to that of Arabidopsis ABA insensitive 5 (ABI5). TaABI5 was classified into the clade of ABI5s in Arabidopsis and rice, unlike TRAB1 of rice, Wabi5 of wheat, and HvABI5 of barley in the bZIP Group A family, by a phylogenetic analysis. TaABI5 was strongly expressed in seeds during the late ripening and maturing stages; however, its expression level markedly decreased after germination. An in situ hybridization analysis showed that TaABI5 mRNA accumulated in seed embryos, particularly the scutellum. In a transient assay using wheat aleurone cells, TaABI5 activated the promoter of Em containing ABRE, which is an embryogenesis abundant protein gene, indicating that TaABI5 acts as a transcription factor in wheat seeds. Furthermore, the seeds of transgenic Arabidopsis lines introduced with 35S:TaABI5 exhibited high sensitivity to ABA and the inhibition of germination. The seed dormancy of the transgenic Arabidopsis lines was stronger than that of Col. These results support TaABI5 playing an important role in mature seeds, particularly before seed germination, and acting as a functional ortholog to Arabidopsis ABI5.


Assuntos
Proteínas de Arabidopsis/fisiologia , Fatores de Transcrição de Zíper de Leucina Básica/fisiologia , Germinação , Sementes/fisiologia , Triticum/fisiologia , Ácido Abscísico/farmacologia , Arabidopsis , Regulação da Expressão Gênica de Plantas , Filogenia , Plantas Geneticamente Modificadas , Triticum/genética
10.
J Plant Res ; 133(2): 231-244, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31915951

RESUMO

Plant growth promoting rhizobacteria (PGPR) are a group of bacteria that promote plants growth in the rhizosphere. PGPRs are involved in various mechanisms that reinforce plant development. In this study, we screened for PGPRs that were effective in early growth of Arabidopsis thaliana when added to the media and one Bacillus subtilis strain L1 (Bs L1) was selected for further study. When Bs L1 was placed near the roots, seedlings showed notably stronger growth than that in the control, particularly in biomass and root hair. Quantitative reverse transcription polymerase chain reaction analysis revealed a high level of expression of the high affinity nitrate transporter gene, NRT2.1 in A. thaliana treated with Bs L1. After considering how Bs L1 could promote plant growth, we focused on nitrate, which is essential to plant growth. The nitrate content was lower in A. thaliana treated with Bs L1. However, examination of the activity of nitrate reductase revealed higher activity in plants treated with PGPR than in the control. Bs L1 had pronounced effects in representative crops (wheat and lettuce). These results suggest that Bs L1 promotes the assimilation and use of nitrate and plant growth.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Bacillus subtilis/fisiologia , Alface/crescimento & desenvolvimento , Nitrato Redutase/fisiologia , Triticum/genética , Proteínas de Transporte de Ânions/fisiologia , Arabidopsis/enzimologia , Proteínas de Arabidopsis/fisiologia , Alface/enzimologia , Nitratos/metabolismo , Proteínas de Plantas/fisiologia , Raízes de Plantas/microbiologia , Triticum/enzimologia
11.
Plant Mol Biol ; 102(4-5): 447-462, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31898148

RESUMO

KEY MESSAGE: ZjICE2 works as a positive regulator in abiotic stress responses and ZjICE2 is a valuable genetic resource to improve abiotic stress tolerance in the molecular breeding program of Zoysia japonica. The basic helix-loop-helix (bHLH) family transcription factors (TFs) play an important role in response to biotic or abiotic stresses in plants. However, the functions of bHLH TFs in Zoysia japonica, one of the warm-season turfgrasses, remain poorly understood. Here, we identified ZjICE2 from Z. japonica, a novel MYC-type bHLH transcription factor that was closely related to ICE homologs in the phylogenetic tree, and its expression was regulated by various abiotic stresses. Transient expression of ZjICE2-GFP in onion epidermal cells revealed that ZjICE2 was a nuclear-localized protein. Also, ZjICE2 bound the MYC cis-element in the promoter of dehydration responsive element binding 1 of Z. japonica (ZjDREB1) using yeast one-hybrid assay. A phenotypic analysis showed that overexpression of the ZjICE2 in Arabidopsis enhanced tolerance to cold, drought, and salt stresses. The transgenic Arabidopsis and Z. japonica accumulated more transcripts of cold-responsive DREB/CBFs and their downstream genes than the wild type (WT) after cold treatment. Furthermore, the transgenic plants exhibited an enhanced Reactive oxygen species (ROS) scavenging ability, which resulted in an efficient maintenance of oxidant-antioxidant homeostasis. In addition, overexpression of the ZjICE2 in Z. japonica displayed intensive cold tolerance with increases in chlorophyll contents and photosynthetic efficiency. Our study suggests that ZjICE2 works as a positive regulator in abiotic stress responses and the ICE-DREB/CBFs response pathway involved in cold stress tolerance is also conserved in Z. japonica. These results provide a valuable genetic resource for the molecular breeding program especially for warm-season grasses as well as other leaf crop plants.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/fisiologia , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/fisiologia , Poaceae/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Estresse Fisiológico , Arabidopsis/genética , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/fisiologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Temperatura Baixa , Resposta ao Choque Frio , Secas , Filogenia , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/fisiologia , Poaceae/genética , Regulon , Tolerância ao Sal , Fatores de Transcrição/genética , Fatores de Transcrição/fisiologia , Ativação Transcricional
12.
Physiol Plant ; 168(3): 709-724, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31381165

RESUMO

5-aminolevulinic acid (ALA), a plant growth regulator with great application potential in agriculture and horticulture, induces stomatal opening and inhibits stomatal closure by decreasing guard cell H2 O2 . However, the mechanisms behind ALA-decreased H2 O2 in guard cells are not fully understood. Here, using type 2A protein phosphatase (PP2A) inhibitors, microtubule-stabilizing/disrupting drugs and green fluorescent protein-tagged α-tubulin 6 transgenic Arabidopsis (GFP-TUA6), we find that PP2A and cortical microtubules (MTs) are involved in ALA-regulated stomatal movement. Then, we analyze stomatal responses of Arabidopsis overexpressing C2 catalytic subunit of PP2A (PP2A-C2) and pp2a-c2 mutant to ALA and abscisic acid (ABA) under both light and dark conditions, and show that PP2A-C2 participates in ALA-induced stomatal movement. Furthermore, using pharmacological methods and confocal studies, we reveal that PP2A and MTs function upstream and downstream, respectively, of H2 O2 in guard cell signaling. Finally, we demonstrate the role of H2 O2 -mediated microtubule arrangement in ALA inhibiting ABA-induced stomatal closure. Our findings indicate that MTs regulated by PP2A-mediated H2 O2 decreasing play an important role in ALA guard cell signaling, revealing new insights into stomatal movement regulation.


Assuntos
Ácido Aminolevulínico/farmacologia , Proteínas de Arabidopsis/fisiologia , Arabidopsis/fisiologia , Peróxido de Hidrogênio/metabolismo , Microtúbulos/fisiologia , Fosfoproteínas Fosfatases/fisiologia , Estômatos de Plantas/fisiologia , Ácido Abscísico , Estômatos de Plantas/citologia , Transdução de Sinais
13.
Physiol Plant ; 168(3): 660-674, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31343741

RESUMO

Arabidopsis thaliana ENO2 (AtENO2) plays an important role in plant growth and development. It encodes two proteins, a full-length AtENO2 and a truncated version, AtMBP-1, alternatively translated from the second start codon of the mRNA. The AtENO2 mutant (eno2- ) exhibited reduced leaf size, shortened siliques, a dwarf phenotype and higher sensitivity to abiotic stress. The objectives of this study were to analyze the regulatory network of the ENO2 gene in plant growth development and understand the function of AtENO2/AtMBP-1 to abiotic stresses. An eno2- /35S:AtENO2-GFP line and an eno2- /35S:AtMBP-1-GFP line of Arabidopsis were obtained. Results of sequencing by 454 GS FLX identified 578 upregulated and 720 downregulated differential expressed genes (DEGs) in a pairwise comparison (WT-VS-eno2- ). All the high-quality reads were annotated using the Gene Ontology (GO) terms. The DEGs with KEGG pathway annotations occurred in 110 pathways. The metabolic pathways and biosynthesis of secondary metabolites contained more DEGs. Moreover, the eno2- /35S:AtENO2-GFP line returned to the wild-type (WT) phenotype and was tolerant to drought and salt stresses. However, the eno2- /35S:AtMBP-1-GFP line was not able to recover the WT phenotype but it has a higher tolerance to drought and salt stresses. Results from this study demonstrate that AtENO2 is critical for the growth and development, and the AtMBP-1 coded by AtENO2 is important in tolerance of Arabidopsis to abiotic stresses.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/fisiologia , Secas , Estresse Salino , Proteínas de Transporte , Regulação da Expressão Gênica de Plantas , Plantas Geneticamente Modificadas
14.
Plant Mol Biol ; 102(4-5): 359-372, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31848919

RESUMO

KEY MESSAGE: Protein degradation is essential in plant growth and development. The stability of Cullin3 substrate adaptor protein BPM1 is regulated by multiple environmental cues pointing on manifold control of targeted protein degradation. A small family of six MATH-BTB genes (BPM1-6) is described in Arabidopsis thaliana. BPM proteins are part of the Cullin E3 ubiquitin ligase complexes and are known to bind at least three families of transcription factors: ERF/AP2 class I, homeobox-leucine zipper and R2R3 MYB. By targeting these transcription factors for ubiquitination and subsequent proteasomal degradation, BPMs play an important role in plant flowering, seed development and abiotic stress response. In this study, we generated BPM1-overexpressing plants that showed an early flowering phenotype, resistance to abscisic acid and tolerance to osmotic stress. We analyzed BPM1-GFP protein stability and found that the protein has a high turnover rate and is degraded by the proteasome 26S in a Cullin-dependent manner. Finally, we found that BPM1 protein stability is environmentally conditioned. Darkness and salt stress triggered BPM1 degradation, whereas elevated temperature enhanced BPM1 stability and accumulation in planta.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/fisiologia , Flores/fisiologia , Estresse Fisiológico , Fatores de Transcrição/fisiologia , Ácido Abscísico , Arabidopsis/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Proteínas de Fluorescência Verde , Raízes de Plantas/fisiologia , Plantas Geneticamente Modificadas , Plasmídeos/genética , Pólen/fisiologia , Complexo de Endopeptidases do Proteassoma/fisiologia , Proteólise , Sementes/fisiologia , Ubiquitina-Proteína Ligases/fisiologia
15.
Biochim Biophys Acta Gen Subj ; 1864(3): 129506, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31870857

RESUMO

BACKGROUND: Fully intrinsically disordered plant dehydrin ERD14 can protect enzymes via its chaperone-like activity, but it was not formally linked with enzymes of the plant redox system yet. This is of particular interest, as the level of H2O2 in Arabidopsis plants increases during osmotic stress, which can be counteracted by overexpression of ERD14. METHODS: The proteomic mass-spectrometry analysis of stressed plants was performed to find the candidates affected by ERD14. With cross-linking, microscale thermophoresis, and active-site titration kinetics, the interaction and influence of ERD14 on the function of two target proteins: glutathione transferase Phi9 and catalase was examined. RESULTS: Under osmotic stress, redox enzymes, specifically the glutathione transferase Phi enzymes, are upregulated. Using microscale thermophoresis, we showed that ERD14 directly interacts with GSTF9 with a KD of ~25 µM. ERD14 activates the inactive GSTF9 molecules, protects GSTF9 from oxidation, and can also increases the activity of the enzyme. Aside from GSTF9, we found that ERD14 can also interact with catalase, an important cellular H2O2 scavenging enzyme, with a KD of ~0.13 µM, and protects it from dehydration-induced loss of activity. CONCLUSIONS: We propose that fully intrinsically disordered dehydrin ERD14 might protect and even activate redox enzymes, helping plants to survive oxidative stress under dehydration conditions. GENERAL SIGNIFICANCE: ERD14 has a direct effect on the activity of redox enzymes.


Assuntos
Proteínas de Arabidopsis/metabolismo , Glutationa Transferase/metabolismo , Arabidopsis/enzimologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/fisiologia , Glutationa Transferase/química , Peróxido de Hidrogênio/metabolismo , Espectrometria de Massas , Pressão Osmótica , Oxirredução , Estresse Oxidativo/fisiologia , Proteínas de Plantas/metabolismo , Dobramento de Proteína , Proteômica
16.
Proc Natl Acad Sci U S A ; 116(51): 25395-25397, 2019 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-31792194

RESUMO

Circadian clocks usually run with a period close to 24 h, but are also plastic and can be entrained by external environmental conditions and internal physiological cues. Two key nutrient metabolites, glucose and vitamin B3 (nicotinamide), can influence the circadian period in both mammals and plants; however, the underlying molecular mechanism is still largely unclear. We reveal that the target of rapamycin (TOR) kinase, a conserved central growth regulator, is essential for glucose- and nicotinamide-mediated control of the circadian period in Arabidopsis Nicotinamide affects the cytosolic adenosine triphosphate concentration, and blocks the effect of glucose-TOR energy signaling on period length adjustment, meristem activation, and root growth. Together, our results uncover a missing link between cellular metabolites, energy status, and circadian period adjustment, and identify TOR kinase as an essential energy sensor to coordinate circadian clock and plant growth.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Relógios Circadianos/fisiologia , Fosfatidilinositol 3-Quinases , Transdução de Sinais/fisiologia , Arabidopsis/metabolismo , Arabidopsis/fisiologia , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/fisiologia , Glucose/metabolismo , Niacinamida/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Fosfatidilinositol 3-Quinases/fisiologia
17.
Nat Plants ; 5(11): 1154-1166, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31712757

RESUMO

Plants strictly regulate the levels of sterol in their cells, as high sterol levels are toxic. However, how plants achieve sterol homeostasis is not fully understood. We isolated an Arabidopsis thaliana mutant that abundantly accumulated sterol esters in structures of about 1 µm in diameter in leaf cells. We designated the mutant high sterol ester 1 (hise1) and called the structures sterol ester bodies. Here, we show that HISE1, the gene product that is altered in this mutant, functions as a key factor in plant sterol homeostasis on the endoplasmic reticulum (ER) and participates in a fail-safe regulatory system comprising two processes. First, HISE1 downregulates the protein levels of the ß-hydroxy ß-methylglutaryl-CoA reductases HMGR1 and HMGR2, which are rate-limiting enzymes in the sterol synthesis pathway, resulting in suppression of sterol overproduction. Second, if the first process is not successful, excess sterols are converted to sterol esters by phospholipid sterol acyltransferase1 (PSAT1) on ER microdomains and then segregated in SE bodies.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/metabolismo , Fitosteróis/metabolismo , Aciltransferases/metabolismo , Arabidopsis/enzimologia , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Retículo Endoplasmático/metabolismo , Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Homeostase , Hidroximetilglutaril-CoA Redutases/genética , Mutação , Folhas de Planta/metabolismo
18.
Nat Plants ; 5(11): 1145-1153, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31712761

RESUMO

The Arabidopsis genome contains three genes encoding proteins of the TRANSPARENT TESTA GLABRA 1 (TTG1) WD-repeat (WDR) subfamily. TTG1 is a known regulator of epidermal cell differentiation and pigment production, while LIGHT-REGULATED WD1 and LIGHT-REGULATED WD2 are known regulators of the circadian clock. Here, we discovered a new central role for TTG1 WDR proteins as regulators of the circadian system, as evidenced by the lack of detectable circadian rhythms in a triple lwd1 lwd2 ttg1 mutant. This shows that there has been subfunctionalization via protein changes within the angiosperms, with some TTG1 WDR proteins developing a stronger role in circadian clock regulation while losing the protein characteristics essential for pigment production and epidermal cell specification, and others weakening their ability to drive circadian clock regulation. Our work shows that even where proteins are very conserved, small changes can drive big functional differences.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/fisiologia , Pigmentação/fisiologia , Células Vegetais/fisiologia , Epiderme Vegetal/citologia , Arabidopsis/citologia , Diferenciação Celular
19.
Nat Commun ; 10(1): 5299, 2019 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-31757966

RESUMO

In plants and cyanobacteria, the PGR5 protein contributes to cyclic electron flow around photosystem I. In plants, PGR5 interacts with PGRL1 during cyclic electron flow, but cyanobacteria appear to lack PGRL1 proteins. We have heterologously expressed the PGR5 and PGRL1 proteins from the plant Arabidopsis in various genetic backgrounds in the cyanobacterium Synechocystis. Our results show that plant PGR5 suffices to re-establish cyanobacterial cyclic electron flow (CEF), albeit less efficiently than the cyanobacterial PGR5 or the plant PGR5 and PGRL1 proteins together. A mutation that inactivates Arabidopsis PGR5 destabilises the protein in Synechocystis. Furthermore, the Synechocystis protein Sll1217, which exhibits weak sequence similarity with PGRL1, physically interacts with both plant and cyanobacterial PGR5 proteins, and stimulates CEF in Synechocystis. Therefore, Sll1217 partially acts as a PGRL1 analogue, the mode of action of PGR5 and PGRL1/Sll1217 proteins is similar in cyanobacteria and plants, and PGRL1 could have evolved from a cyanobacterial ancestor.


Assuntos
Proteínas de Arabidopsis/genética , Transporte de Elétrons/genética , Proteínas de Membrana/genética , Complexo de Proteínas do Centro de Reação Fotossintética/genética , Synechocystis/genética , Arabidopsis , Proteínas de Arabidopsis/fisiologia , Transporte de Elétrons/fisiologia , Proteínas de Membrana/fisiologia , Mutação , Fotossíntese , Complexo de Proteínas do Centro de Reação Fotossintética/fisiologia , Complexo de Proteína do Fotossistema I/genética , Complexo de Proteína do Fotossistema I/metabolismo , Synechocystis/metabolismo
20.
BMC Plant Biol ; 19(1): 524, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31775615

RESUMO

BACKGROUND: Plastid-encoded RNA polymerase (PEP) plays an essential role in chloroplast development by governing the expression of genes involved in photosynthesis. At least 12 PEP-associated proteins (PAPs), including FSD3/PAP4, regulate PEP activity and chloroplast development by modulating formation of the PEP complex. RESULTS: In this study, we identified FSD3S, a splicing variant of FSD3; the FSD3 and FSD3S transcripts encode proteins with identical N-termini, but different C-termini. Characterization of FSD3 and FSD3S proteins showed that the C-terminal region of FSD3S contains a transmembrane domain, which promotes FSD3S localization to the chloroplast membrane but not to nucleoids, in contrast to FSD3, which localizes to the chloroplast nucleoid. We also found that overexpression of FSD3S negatively affects photosynthetic activity and chloroplast development by reducing expression of genes involved in photosynthesis. In addition, FSD3S failed to complement the chloroplast developmental defects in the fsd3 mutant. CONCLUSION: These results suggest FSD3 and FSD3S, with their distinct localization patterns, have different functions in chloroplast development, and FSD3S negatively regulates expression of PEP-dependent chloroplast genes, and development of chloroplasts.


Assuntos
Proteínas de Arabidopsis/fisiologia , Proteínas de Cloroplastos/fisiologia , Cloroplastos/fisiologia , Plastídeos/genética , Processamento Alternativo , Arabidopsis , Proteínas de Arabidopsis/genética , Proteínas de Cloroplastos/genética , Cloroplastos/genética , RNA Polimerases Dirigidas por DNA/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/fisiologia , Isoformas de Proteínas/genética , Isoformas de Proteínas/fisiologia , Superóxido Dismutase/metabolismo
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