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1.
Nucleic Acids Res ; 49(19): 11274-11293, 2021 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-34614168

RESUMO

In plants and some animal lineages, RNA silencing is an efficient and adaptable defense mechanism against viruses. To counter it, viruses encode suppressor proteins that interfere with RNA silencing. Phloem-restricted viruses are spreading at an alarming rate and cause substantial reduction of crop yield, but how they interact with their hosts at the molecular level is still insufficiently understood. Here, we investigate the antiviral response against phloem-restricted turnip yellows virus (TuYV) in the model plant Arabidopsis thaliana. Using a combination of genetics, deep sequencing, and mechanical vasculature enrichment, we show that the main axis of silencing active against TuYV involves 22-nt vsiRNA production by DCL2, and their preferential loading into AGO1. Moreover, we identify vascular secondary siRNA produced from plant transcripts and initiated by DCL2-processed AGO1-loaded vsiRNA. Unexpectedly, and despite the viral encoded VSR P0 previously shown to mediate degradation of AGO proteins, vascular AGO1 undergoes specific post-translational stabilization during TuYV infection. Collectively, our work uncovers the complexity of antiviral RNA silencing against phloem-restricted TuYV and prompts a re-assessment of the role of its suppressor of silencing P0 during genuine infection.

2.
Int J Mol Sci ; 22(17)2021 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-34502465

RESUMO

Due to their sessile lifestyle, plants are especially exposed to various stresses, including genotoxic stress, which results in altered genome integrity. Upon the detection of DNA damage, distinct cellular responses lead to cell cycle arrest and the induction of DNA repair mechanisms. Interestingly, it has been shown that some cell cycle regulators are not only required for meristem activity and plant development but are also key to cope with the occurrence of DNA lesions. In this review, we first summarize some important regulatory steps of the plant cell cycle and present a brief overview of the DNA damage response (DDR) mechanisms. Then, the role played by some cell cycle regulators at the interface between the cell cycle and DNA damage responses is discussed more specifically.


Assuntos
Ciclo Celular , Dano ao DNA , DNA de Plantas/metabolismo , Plantas/metabolismo , DNA de Plantas/genética , Plantas/genética
3.
Plant Cell ; 33(11): 3402-3420, 2021 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-34436604

RESUMO

Plant RNA viruses form organized membrane-bound replication complexes to replicate their genomes. This process requires virus- and host-encoded proteins and leads to the production of double-stranded RNA (dsRNA) replication intermediates. Here, we describe the use of Arabidopsis thaliana expressing GFP-tagged dsRNA-binding protein (B2:GFP) to pull down dsRNA and associated proteins in planta upon infection with Tobacco rattle virus (TRV). Mass spectrometry analysis of the dsRNA-B2:GFP-bound proteins from infected plants revealed the presence of viral proteins and numerous host proteins. Among a selection of nine host candidate proteins, eight showed relocalization upon infection, and seven of these colocalized with B2-labeled TRV replication complexes. Infection of A. thaliana T-DNA mutant lines for eight such factors revealed that genetic knockout of dsRNA-BINDING PROTEIN 2 (DRB2) leads to increased TRV accumulation and DRB2 overexpression caused a decrease in the accumulation of four different plant RNA viruses, indicating that DRB2 has a potent and wide-ranging antiviral activity. We propose B2:GFP-mediated pull down of dsRNA to be a versatile method to explore virus replication complex proteomes and to discover key host virus replication factors. Given the universality of dsRNA, development of this tool holds great potential to investigate RNA viruses in other host organisms.

5.
Plant Physiol ; 183(3): 1295-1305, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32414898

RESUMO

In Arabidopsis (Arabidopsis thaliana), the F-box protein F-BOX-LIKE17 (FBL17) was previously identified as an important cell-cycle regulatory protein. FBL17 is required for cell division during pollen development and for normal cell-cycle progression and endoreplication during the diploid sporophyte phase. FBL17 was reported to control the stability of the CYCLIN-DEPENDENT KINASE inhibitor KIP-RELATED PROTEIN (KRP), which may underlie the drastic reduction in cell division activity in both shoot and root apical meristems observed in fbl17 loss-of-function mutants. However, whether FBL17 has other substrates and functions besides degrading KRPs remains poorly understood. Here we show that mutation of FBL17 leads not only to misregulation of cell cycle genes, but also to a strong upregulation of genes involved in DNA damage and repair processes. This phenotype is associated with a higher frequency of DNA lesions in fbl17 and increased cell death in the root meristem, even in the absence of genotoxic stress. Notably, the constitutive activation of DNA damage response genes is largely SOG1-independent in fbl17 In addition, through analyses of root elongation, accumulation of cell death, and occurrence of γH2AX foci, we found that fbl17 mutants are hypersensitive to DNA double-strand break-induced genotoxic stress. Notably, we observed that the FBL17 protein is recruited at nuclear foci upon double-strand break induction and colocalizes with γH2AX, but only in the presence of RETINOBLASTOMA RELATED1. Altogether, our results highlight a role for FBL17 in DNA damage response, likely by ubiquitylating proteins involved in DNA-damage signaling or repair.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Dano ao DNA , DNA de Plantas/metabolismo , Proteínas F-Box/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Bleomicina/farmacologia , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Quebras de DNA de Cadeia Dupla/efeitos dos fármacos , Reparo do DNA/efeitos dos fármacos , Reparo do DNA/genética , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Mutação/genética , Fatores de Transcrição/metabolismo , Transcriptoma/genética , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/genética
6.
Proc Natl Acad Sci U S A ; 117(11): 6205-6215, 2020 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-32123086

RESUMO

The jasmonate (JA)-pathway regulators MYC2, MYC3, and MYC4 are central nodes in plant signaling networks integrating environmental and developmental signals to fine-tune JA defenses and plant growth. Continuous activation of MYC activity is potentially lethal. Hence, MYCs need to be tightly regulated in order to optimize plant fitness. Among the increasing number of mechanisms regulating MYC activity, protein stability is arising as a major player. However, how the levels of MYC proteins are modulated is still poorly understood. Here, we report that MYC2, MYC3, and MYC4 are targets of BPM (BTB/POZ-MATH) proteins, which act as substrate adaptors of CUL3-based E3 ubiquitin ligases. Reduction of function of CUL3BPM in amiR-bpm lines, bpm235 triple mutants, and cul3ab double mutants enhances MYC2 and MYC3 stability and accumulation and potentiates plant responses to JA such as root-growth inhibition and MYC-regulated gene expression. Moreover, MYC3 polyubiquitination levels are reduced in amiR-bpm lines. BPM3 protein is stabilized by JA, suggesting a negative feedback regulatory mechanism to control MYC activity, avoiding harmful runaway responses. Our results uncover a layer for JA-pathway regulation by CUL3BPM-mediated degradation of MYC transcription factors.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Proteínas Culina/metabolismo , Ciclopentanos/metabolismo , Regulação da Expressão Gênica de Plantas/fisiologia , Oxilipinas/metabolismo , Proteínas de Arabidopsis/genética , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Proteínas Culina/genética , Retroalimentação Fisiológica , Mutação , Raízes de Plantas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas , Estabilidade Proteica , Proteólise , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Transativadores/genética , Transativadores/metabolismo , Ubiquitinação/fisiologia
7.
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
8.
Plant J ; 101(6): 1303-1317, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31659801

RESUMO

Agrobacterium T-DNA-encoded 6B proteins cause remarkable growth effects in plants. Nicotiana otophora carries two cellular T-DNAs with three slightly divergent 6b genes (TE-1-6b-L, TE-1-6b-R and TE-2-6b) originating from a natural transformation event. In Arabidopsis thaliana, expression of 2×35S:TE-2-6b, but not 2×35S:TE-1-6b-L or 2×35S:TE-1-6b-R, led to plants with crinkly leaves, which strongly resembled mutants of the miR319a/TCP module. This module is composed of MIR319A and five CIN-like TCP (TEOSINTHE BRANCHED1, CYCLOIDEA and PROLIFERATING CELL NUCLEAR ANTIGEN BINDING FACTOR) genes (TCP2, TCP3, TCP4, TCP10 and TCP24) targeted by miR319a. The CIN-like TCP genes encode transcription factors and are required for cell division arrest at leaf margins during development. MIR319A overexpression causes excessive growth and crinkly leaves. TE-2-6b plants did not show increased miR319a levels, but the mRNA levels of the TCP4 target gene LOX2 were decreased, as in jaw-D plants. Co-expression of green fluorescent protein (GFP)-tagged TCPs with native or red fluorescent protein (RFP)-tagged TE-6B proteins led to an increase in TCP protein levels and formation of numerous cytoplasmic dots containing 6B and TCP proteins. Yeast double-hybrid experiments confirmed 6B/TCP binding and showed that TE-1-6B-L and TE-1-6B-R bind a smaller set of TCP proteins than TE-2-6B. A single nucleotide mutation in TE-1-6B-R enlarged its TCP-binding repertoire to that of TE-2-6B and caused a crinkly phenotype in Arabidopsis. Deletion analysis showed that TE-2-6B targets the TCP4 DNA-binding domain and directly interferes with transcriptional activation. Taken together, these results provide detailed insights into the mechanism of action of the N. otophora TE-encoded 6b genes.


Assuntos
Agrobacterium/metabolismo , Arabidopsis/metabolismo , Proteínas de Bactérias/metabolismo , DNA Bacteriano/metabolismo , Fatores de Transcrição/antagonistas & inibidores , Arabidopsis/microbiologia , Proteínas de Arabidopsis/antagonistas & inibidores , Proteínas de Arabidopsis/metabolismo , Perfilação da Expressão Gênica , Microscopia Confocal , Doenças das Plantas/microbiologia , Folhas de Planta/metabolismo , Folhas de Planta/microbiologia , Reação em Cadeia da Polimerase , Tabaco/metabolismo , Tabaco/microbiologia , Técnicas do Sistema de Duplo-Híbrido
9.
Proc Natl Acad Sci U S A ; 116(45): 22872-22883, 2019 11 05.
Artigo em Inglês | MEDLINE | ID: mdl-31628252

RESUMO

RNA silencing is a major antiviral defense mechanism in plants and invertebrates. Plant ARGONAUTE1 (AGO1) is pivotal in RNA silencing, and hence is a major target for counteracting viral suppressors of RNA-silencing proteins (VSRs). P0 from Turnip yellows virus (TuYV) is a VSR that was previously shown to trigger AGO1 degradation via an autophagy-like process. However, the identity of host proteins involved and the cellular site at which AGO1 and P0 interact were unknown. Here we report that P0 and AGO1 associate on the endoplasmic reticulum (ER), resulting in their loading into ER-associated vesicles that are mobilized to the vacuole in an ATG5- and ATG7-dependent manner. We further identified ATG8-Interacting proteins 1 and 2 (ATI1 and ATI2) as proteins that associate with P0 and interact with AGO1 on the ER up to the vacuole. Notably, ATI1 and ATI2 belong to an endogenous degradation pathway of ER-associated AGO1 that is significantly induced following P0 expression. Accordingly, ATI1 and ATI2 deficiency causes a significant increase in posttranscriptional gene silencing (PTGS) activity. Collectively, we identify ATI1 and ATI2 as components of an ER-associated AGO1 turnover and proper PTGS maintenance and further show how the VSR P0 manipulates this pathway.


Assuntos
Proteínas Argonauta/metabolismo , Autofagia , Retículo Endoplasmático/metabolismo , Proteínas de Membrana/metabolismo , Proteínas de Plantas/metabolismo , Proteínas Virais/metabolismo , Proteólise , Vacúolos/metabolismo
10.
Proc Natl Acad Sci U S A ; 116(31): 15725-15734, 2019 07 30.
Artigo em Inglês | MEDLINE | ID: mdl-31308219

RESUMO

Early abscisic acid signaling involves degradation of clade A protein phosphatases type 2C (PP2Cs) as a complementary mechanism to PYR/PYL/RCAR-mediated inhibition of PP2C activity. At later steps, ABA induces up-regulation of PP2C transcripts and protein levels as a negative feedback mechanism. Therefore, resetting of ABA signaling also requires PP2C degradation to avoid excessive ABA-induced accumulation of PP2Cs. It has been demonstrated that ABA induces the degradation of existing ABI1 and PP2CA through the PUB12/13 and RGLG1/5 E3 ligases, respectively. However, other unidentified E3 ligases are predicted to regulate protein stability of clade A PP2Cs as well. In this work, we identified BTB/POZ AND MATH DOMAIN proteins (BPMs), substrate adaptors of the multimeric cullin3 (CUL3)-RING-based E3 ligases (CRL3s), as PP2CA-interacting proteins. BPM3 and BPM5 interact in the nucleus with PP2CA as well as with ABI1, ABI2, and HAB1. BPM3 and BPM5 accelerate the turnover of PP2Cs in an ABA-dependent manner and their overexpression leads to enhanced ABA sensitivity, whereas bpm3 bpm5 plants show increased accumulation of PP2CA, ABI1 and HAB1, which leads to global diminished ABA sensitivity. Using biochemical and genetic assays, we demonstrated that ubiquitination of PP2CA depends on BPM function. Given the formation of receptor-ABA-phosphatase ternary complexes is markedly affected by the abundance of protein components and ABA concentration, we reveal that BPMs and multimeric CRL3 E3 ligases are important modulators of PP2C coreceptor levels to regulate early ABA signaling as well as the later desensitizing-resetting steps.


Assuntos
Ácido Abscísico/farmacocinética , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas Culina/metabolismo , Fosfoproteínas Fosfatases/metabolismo , Proteólise , Motivos de Aminoácidos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas Culina/genética , Fosfoproteínas Fosfatases/genética
11.
Plant Cell ; 31(8): 1734-1750, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31189739

RESUMO

Regulated gene expression is key to the orchestrated progression of the cell cycle. Many genes are expressed at specific points in the cell cycle, including important cell cycle regulators, plus factors involved in signal transduction, hormonal regulation, and metabolic control. We demonstrate that post-embryonic depletion of Arabidopsis (Arabidopsis thaliana) ARGONAUTE1 (AGO1), the main effector of plant microRNAs (miRNAs), impairs cell division in the root meristem. We utilized the highly synchronizable tobacco (Nicotiana tabacum) Bright yellow 2 (BY2) cell suspension to analyze mRNA, small RNAs, and mRNA cleavage products of synchronized BY2 cells at S, G2, M, and G1 phases of the cell cycle. This revealed that in plants, only a few miRNAs show differential accumulation during the cell cycle, and miRNA-target pairs were only identified for a small proportion of the more than 13,000 differentially expressed genes during the cell cycle. However, this unique set of miRNA-target pairs could be key to attenuate the expression of several transcription factors and disease resistance genes. We also demonstrate that AGO1 binds to a set of 19-nucleotide, tRNA-derived fragments during the cell cycle progression.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Arabidopsis/fisiologia , Proteínas Argonauta/metabolismo , Ciclo Celular/fisiologia , Regulação da Expressão Gênica de Plantas/fisiologia , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas Argonauta/genética , Ciclo Celular/genética , Regulação da Expressão Gênica de Plantas/genética , MicroRNAs/genética , MicroRNAs/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
13.
Plant Cell ; 30(6): 1353-1374, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29848768

RESUMO

In Arabidopsis thaliana, ARGONAUTE1 (AGO1) plays a central role in microRNA (miRNA) and small interfering RNA (siRNA)-mediated silencing and is a key component in antiviral responses. The polerovirus F-box P0 protein triggers AGO1 degradation as a viral counterdefense. Here, we identified a motif in AGO1 that is required for its interaction with the S phase kinase-associated protein1-cullin 1-F-box protein (SCF) P0 (SCFP0) complex and subsequent degradation. The AGO1 P0 degron is conserved and confers P0-mediated degradation to other AGO proteins. Interestingly, the degron motif is localized in the DUF1785 domain of AGO1, in which a single point mutation (ago1-57, obtained by forward genetic screening) compromises recognition by SCFP0 Recapitulating formation of the RNA-induced silencing complex in a cell-free system revealed that this mutation impairs RNA unwinding, leading to stalled forms of AGO1 still bound to double-stranded RNAs. In vivo, the DUF1785 is required for unwinding perfectly matched siRNA duplexes, but is mostly dispensable for unwinding imperfectly matched miRNA duplexes. Consequently, its mutation nearly abolishes phased siRNA production and sense transgene posttranscriptional gene silencing. Overall, our work sheds new light on the mode of AGO1 recognition by P0 and the in vivo function of DUF1785 in RNA silencing.


Assuntos
Arabidopsis/metabolismo , RNA de Cadeia Dupla/genética , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas Argonauta/genética , Proteínas Argonauta/metabolismo , Proteínas F-Box/genética , Proteínas F-Box/metabolismo , Mutação Puntual/genética , Interferência de RNA
14.
Proc Natl Acad Sci U S A ; 115(17): E4130-E4139, 2018 04 24.
Artigo em Inglês | MEDLINE | ID: mdl-29643073

RESUMO

The gaseous hormone ethylene plays a key role in plant growth and development, and it is a major regulator of stress responses. It inhibits vegetative growth by restricting cell elongation, mainly through cross-talk with auxins. However, it remains unknown whether ethylene controls growth throughout all plant tissues or whether its signaling is confined to specific cell types. We employed a targeted expression approach to map the tissue site(s) of ethylene growth regulation. The ubiquitin E3 ligase complex containing Skp1, Cullin1, and the F-box protein EBF1 or EBF2 (SCFEBF1/2) target the degradation of EIN3, the master transcription factor in ethylene signaling. We coupled EBF1 and EBF2 to a number of cell type-specific promoters. Using phenotypic assays for ethylene response and mutant complementation, we revealed that the epidermis is the main site of ethylene action controlling plant growth in both roots and shoots. Suppression of ethylene signaling in the epidermis of the constitutive ethylene signaling mutant ctr1-1 was sufficient to rescue the mutant phenotype, pointing to the epidermis as a key cell type required for ethylene-mediated growth inhibition.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Etilenos/metabolismo , Epiderme Vegetal/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Teste de Complementação Genética , Mutação , Epiderme Vegetal/genética , Reguladores de Crescimento de Plantas/genética
15.
Plant Physiol ; 176(4): 2834-2850, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29472278

RESUMO

The plant cell cycle is tightly regulated by factors that integrate endogenous cues and environmental signals to adapt plant growth to changing conditions. Under drought, cell division in young leaves is blocked by an active mechanism, reducing the evaporative surface and conserving energy resources. The molecular function of cyclin-dependent kinase-inhibitory proteins (CKIs) in regulating the cell cycle has already been well studied, but little is known about their involvement in cell cycle regulation under adverse growth conditions. In this study, we show that the transcript of the CKI gene SIAMESE-RELATED1 (SMR1) is quickly induced under moderate drought in young Arabidopsis (Arabidopsis thaliana) leaves. Functional characterization further revealed that SMR1 inhibits cell division and affects meristem activity, thereby restricting the growth of leaves and roots. Moreover, we demonstrate that SMR1 is a short-lived protein that is degraded by the 26S proteasome after being ubiquitinated by a Cullin-RING E3 ubiquitin ligase. Consequently, overexpression of a more stable variant of the SMR1 protein leads to a much stronger phenotype than overexpression of the native SMR1. Under moderate drought, both the SMR1 transcript and SMR1 protein accumulate. Despite this induction, smr1 mutants do not show overall tolerance to drought stress but do show less growth inhibition of young leaves under drought. Surprisingly, the growth-repressive hormone ethylene promotes SMR1 induction, but the classical drought hormone abscisic acid does not.


Assuntos
Proteínas de Arabidopsis/genética , Secas , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Proteínas Nucleares/genética , Folhas de Planta/genética , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Ciclo Celular/genética , Meristema/genética , Meristema/crescimento & desenvolvimento , Meristema/metabolismo , Mutação , Proteínas Nucleares/metabolismo , Fenótipo , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Plantas Geneticamente Modificadas
17.
Trends Plant Sci ; 22(8): 646-648, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28633985

RESUMO

In metazoans, autophagy is an essential component of host defense against viruses, orchestrating their degradation. Such antiviral functions for autophagy have also been long suspected in the green lineage. Two recent reports provide molecular insights on how plants selectively send viral proteins and even particles to the vacuole.


Assuntos
Autofagia , Doenças das Plantas/imunologia , Imunidade Vegetal , Vírus de Plantas/imunologia , Plantas/imunologia , Interações Hospedeiro-Patógeno , Doenças das Plantas/virologia , Plantas/virologia
19.
Plant Cell ; 28(9): 2043-2059, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27531226

RESUMO

In eukaryotes, DNA repair pathways help to maintain genome integrity and epigenomic patterns. However, the factors at the nexus of DNA repair and chromatin modification/remodeling remain poorly characterized. Here, we uncover a previously unrecognized interplay between the DNA repair factor DNA DAMAGE BINDING PROTEIN2 (DDB2) and the DNA methylation machinery in Arabidopsis thaliana Loss-of-function mutation in DDB2 leads to genome-wide DNA methylation alterations. Genetic and biochemical evidence indicate that at many repeat loci, DDB2 influences de novo DNA methylation by interacting with ARGONAUTE4 and by controlling the local abundance of 24-nucleotide short interfering RNAs (siRNAs). We also show that DDB2 regulates active DNA demethylation mediated by REPRESSOR OF SILENCING1 and DEMETER LIKE3. Together, these findings reveal a role for the DNA repair factor DDB2 in shaping the Arabidopsis DNA methylation landscape in the absence of applied genotoxic stress.

20.
Trends Plant Sci ; 21(2): 134-144, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26598298

RESUMO

Autophagy is a major cellular degradation pathway in eukaryotes. Recent studies have revealed the importance of autophagy in many aspects of plant life, including seedling establishment, plant development, stress resistance, metabolism, and reproduction. This is manifested by the dual ability of autophagy to execute bulk degradation under severe environmental conditions, while simultaneously to be highly selective in targeting specific compartments and protein complexes to regulate key cellular processes, even during favorable growth conditions. Delivery of cellular components to the vacuole enables their recycling, affecting the plant metabolome, especially under stress. Recent research in Arabidopsis has further unveiled fundamental mechanistic aspects in autophagy which may have relevance in non-plant systems. We review the most recent discoveries concerning autophagy in plants, touching upon all these aspects.


Assuntos
Autofagia , Plantas/metabolismo , Alimentos , Modelos Biológicos , Pesquisa
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