RESUMO
A double-stranded RNA (dsRNA) HBJZ1506 recovered from the phytopathogenic fungus Erysiphe cichoracearum infecting Calendula officinalis in Jingzhou, Hubei Province, China, was sequenced. HBJZ1506 comprises 11,908 nucleotides (nt) and contains a 11,859-nt-long open reading frame (ORF) coding for a polypeptide that is 61 % identical to that of a putative endornavirus named grapevine endophyte endornavirus (GeEV). The putative polyprotein has an RNA-dependent RNA polymerase (RdRp) domain and an RNA helicase domain, which show homology to and have an arrangement that is similar to that of their counterparts in approved or putative endornaviruses. In a phylogenetic tree constructed using amino acid sequences of the RdRp region of HBJZ1506 and selected endornaviruses, HBJZ1506 clustered with endornaviruses and formed a well-supported monophyletic branch with GeEV. These results suggest that HBJZ1506 might represent a novel endornavirus, for which the name Erysiphe cichoracearum endornavirus (EcEV) is proposed.
Assuntos
Ascomicetos/virologia , Genoma Viral , Vírus de RNA/genética , RNA de Cadeia Dupla/genética , Sequência de Bases , China , Genômica , Dados de Sequência Molecular , Fases de Leitura Aberta , Filogenia , Vírus de RNA/classificação , Vírus de RNA/isolamento & purificação , RNA Viral/genética , Proteínas Virais/genéticaRESUMO
Rice grassy stunt virus (RGSV), a member of the genus Tenuivirus, causes serious rice disease in Southeast Asian countries. In this study, a green fluorescent protein (GFP)-based transient expression assay was conducted to show that p5, encoded on RNA5 in the viral sense, is a viral suppressor of RNA silencing (VSR). Protein-protein interactions (PPIs) between p5 and all RGSV proteins except pC1 and pC2 were investigated using Gal4-based yeast two-hybrid (Y2H) experiments. The results demonstrated that p5 interacts with itself and with p3 encoded on RNA3 in the viral sense. p5-p5 and p5-p3 interactions were detected by bimolecular fluorescence complementation (BiFC) assay, and the p5-p3 interaction was confirmed by subcellular co-localization and co-immunoprecipitation (Co-IP) assays. Using the Y2H system, we demonstrated that the p5-p3 interaction requires both the N-terminal (amino acid residues 1 to 99) and C-terminal (amino acid residues 94 to 191) domains of p5. In addition, either p5 or p3 could enhance the pathogenicity of potato virus X (PVX) in Nicotiana benthamiana plants. A much more significant enhancement of PVX pathogenicity and accumulation was observed when p5 and p3 were expressed together. Our data also showed that RGSV p3 does not function as a VSR, and it had no effect on the VSR activity of p5 or the subcellular localization pattern of p5 in plant cells from Nicotiana benthamiana.
Assuntos
Doenças das Plantas/virologia , Interferência de RNA , Tenuivirus/genética , Tenuivirus/metabolismo , Proteínas não Estruturais Virais/metabolismo , Ligação Proteica , Nicotiana/virologia , Técnicas do Sistema de Duplo-Híbrido , Proteínas não Estruturais Virais/genéticaRESUMO
BACKGROUND: Rice dwarf virus (RDV) is the causal agent of rice dwarf disease, which limits rice production in many areas of south East Asia. Transcriptional changes of rice in response to RDV infection have been characterized by Shimizu et al. and Satoh et al.. Both studies found induction of defense related genes and correlations between transcriptional changes and symptom development in RDV-infected rice. However, the same rice cultivar, namely Nipponbare belonging to the Japonic subspecies of rice was used in both studies. METHODS: Gene expression changes of the indica subspecies of rice, namely Oryza sativa L. ssp. indica cv Yixiang2292 that show moderate resistance to RDV, in response to RDV infection were characterized using an Affymetrix Rice Genome Array. Differentially expressed genes (DEGs) were classified according to their Gene Ontology (GO) annotation. The effects of transient expression of Pns11 in Nicotiana benthaminana on the expression of nucleolar genes were studied using real-time PCR (RT-PCR). RESULTS: 856 genes involved in defense or other physiological processes were identified to be DEGs, most of which showed up-regulation. Ribosome- and nucleolus related genes were significantly enriched in the DEGs. Representative genes related to nucleolar function exhibited altered expression in N. benthaminana plants transiently expressing Pns11 of RDV. CONCLUSIONS: Induction of defense related genes is common for rice infected with RDV. There is a co-relation between symptom severity and transcriptional alteration in RDV infected rice. Besides ribosome, RDV may also target nucleolus to manipulate the translation machinery of rice. Given the tight links between nucleolus and ribosome, it is intriguing to speculate that RDV may enhance expression of ribosomal genes by targeting nucleolus through Pns11.
Assuntos
Nucléolo Celular/virologia , Perfilação da Expressão Gênica , Interações Hospedeiro-Patógeno , Oryza/virologia , Doenças das Plantas/virologia , Reoviridae/fisiologia , Análise em Microsséries , Oryza/genética , Oryza/imunologia , Doenças das Plantas/imunologia , Reação em Cadeia da Polimerase em Tempo Real , Reoviridae/imunologiaRESUMO
Rice stripe virus (RSV) is one of the most important viral pathogens of rice in East Asia. The origin and dispersal of RSV remain poorly understood, but an emerging hypothesis suggests that: (i) RSV originates from Yunnan, a southwest province of China; and (ii) some places of eastern China have acted as a center for the international dissemination of RSV. This hypothesis, however, has never been tested rigorously. Using a data set comprising more than 200 time-stamped coat protein gene sequences of RSV from Japan, China and South Korea, we reconstructed the phylogeographic history of RSV with Bayesian phylogeographic inference. Unexpectedly, the results did not support the abovementioned hypothesis. Instead, they suggested that RSV originates from Japan and Japan has been the major center for the dissemination of RSV in the past decades. Based on these data and the temporal dynamics of RSV reported recently by another group, we proposed a new hypothesis to explain the origin and dispersal of RSV. This new hypothesis may be valuable for further studies aiming to clarify the epidemiology of RSV. It may also be useful in designing management strategies against this devastating virus.
Assuntos
Oryza , Tenuivirus , Tenuivirus/genética , Japão/epidemiologia , Teorema de Bayes , ChinaRESUMO
The ubiquitin-proteasome system (UPS) is an important post-translational regulatory mechanism that controls many cellular functions in eukaryotes. Here, we show that stable expression of P3 protein encoded by Rice grassy stunt virus (RGSV), a negative-strand RNA virus in the Bunyavirales, causes developmental abnormities similar to the disease symptoms caused by RGSV, such as dwarfing and excess tillering, in transgenic rice plants. We found that both transgenic expression of P3 and RGSV infection induce ubiquitination and UPS-dependent degradation of rice NUCLEAR RNA POLYMERASE D1a (OsNRPD1a), one of two orthologs of the largest subunit of plant-specific RNA polymerase IV (Pol IV), which is required for RNA-directed DNA methylation (RdDM). Furthermore, we identified a P3-inducible U-box type E3 ubiquitin ligase, designated as P3-inducible protein 1 (P3IP1), which interacts with OsNRPD1a and mediates its ubiquitination and UPS-dependent degradation in vitro and in vivo. Notably, both knockdown of OsNRPD1 and overexpression of P3IP1 in rice plants induced developmental phenotypes similar to RGSV disease symptomss. Taken together, our findings reveal a novel virulence mechanism whereby plant pathogens target host RNA Pol IV for UPS-dependent degradation to induce disease symptoms. Our study also identified an E3 ubiquitin ligase, which targets the RdDM compotent NRPD1 for UPS-mediated degradation in rice.
Assuntos
RNA Polimerases Dirigidas por DNA/metabolismo , Oryza/enzimologia , Oryza/virologia , Doenças das Plantas/virologia , Proteínas de Plantas/metabolismo , Proteólise , Tenuivirus/patogenicidade , Ubiquitina-Proteína Ligases/metabolismo , Sequência de Bases , Técnicas de Silenciamento de Genes , Inativação Gênica , Modelos Biológicos , Oryza/genética , Proteínas de Plantas/química , Complexo de Endopeptidases do Proteassoma/metabolismo , Ligação Proteica , Subunidades Proteicas/metabolismo , Tenuivirus/metabolismo , Ubiquitina/metabolismo , Proteínas Virais/metabolismoRESUMO
Combined molecular dynamics (MD) simulation and experiment are adopted to gain the mechanism of water content on the electrochemical surface area (ECSA) of the catalyst layer in a proton exchange membrane fuel cell. The morphology of water domains in the catalyst layer has a strong impact on the ECSA via MD simulation. The morphology of the water domains is isolated water clusters at low water content, resulting in the poor ECSA due to the lack of proton transport paths. The transport paths of protons tend to be quickly established with increasing water content during the transition process of the morphology of water domains from isolated water clusters to the water channel network, thereby leading to the rapid increase of the ECSA. However, the slight increase of the ECSA at high water content mainly results from the improved contact area between water domains and Pt particle instead of the formation of new transport paths. In addition, the stronger binding of water molecules and the Pt particle at low temperature results in a higher ECSA.
RESUMO
High oil and protein content make tetraploid peanut a leading oil and food legume. Here we report a high-quality peanut genome sequence, comprising 2.54 Gb with 20 pseudomolecules and 83,709 protein-coding gene models. We characterize gene functional groups implicated in seed size evolution, seed oil content, disease resistance and symbiotic nitrogen fixation. The peanut B subgenome has more genes and general expression dominance, temporally associated with long-terminal-repeat expansion in the A subgenome that also raises questions about the A-genome progenitor. The polyploid genome provided insights into the evolution of Arachis hypogaea and other legume chromosomes. Resequencing of 52 accessions suggests that independent domestications formed peanut ecotypes. Whereas 0.42-0.47 million years ago (Ma) polyploidy constrained genetic variation, the peanut genome sequence aids mapping and candidate-gene discovery for traits such as seed size and color, foliar disease resistance and others, also providing a cornerstone for functional genomics and peanut improvement.
Assuntos
Arachis/genética , Arachis/embriologia , Arachis/fisiologia , Mapeamento Cromossômico , Cromossomos de Plantas/genética , Resistência à Doença/genética , Domesticação , Secas , Ecótipo , Evolução Molecular , Genoma de Planta , Cariótipo , Óleo de Amendoim/metabolismo , Melhoramento Vegetal , Doenças das Plantas/prevenção & controle , Proteínas de Vegetais Comestíveis/metabolismo , Poliploidia , Sementes/anatomia & histologia , Sementes/genéticaRESUMO
The complete chloroplast sequence of the Anoectochilus roxburghii, a popular traditional Chinese medicine for the treatment of cancer, was determined in this study. The chloroplast genome (cpDNA)^ was 152,802 bp in length, containing a pair of inverted repeats of 52,728 bp separated by a large single-copy region and a small single-copy region of 82,641 bp and 17,433 bp, respectively. The chloroplast genome encodes 116 predicted functional genes, including 81 protein-coding genes, four ribosomal RNA genes, and 31 transfer RNA genes, 25 of which are duplicated in the inverted repeat regions. The cpDNA is GC-rich (36.9%).
Assuntos
Genoma de Cloroplastos , Orchidaceae/classificação , Orchidaceae/genética , Composição de Bases , Biologia Computacional , Genes de Cloroplastos , Tamanho do Genoma , Fases de Leitura Aberta , Filogenia , Análise de Sequência de DNA , Sequenciamento Completo do GenomaRESUMO
MicroRNAs (miRNAs) are pivotal modulators of plant development and host-virus interactions. However, the roles and action modes of specific miRNAs involved in viral infection and host susceptibility remain largely unclear. In this study, we show that Rice ragged stunt virus (RRSV) infection caused increased accumulation of miR319 but decreased expression of miR319-regulated TCP (TEOSINTE BRANCHED/CYCLOIDEA/PCF) genes, especially TCP21, in rice plants. Transgenic rice plants overexpressing miR319 or downregulating TCP21 exhibited disease-like phenotypes and showed significantly higher susceptibility to RRSV in comparison with the wild-type plants. In contrast, only mild disease symptoms were observed in RRSV-infected lines overexpressing TCP21 and especially in the transgenic plants overexpressing miR319-resistant TCP21. Both RRSV infection and overexpression of miR319 caused the decreased endogenous jasmonic acid (JA) levels along with downregulated expression of JA biosynthesis and signaling-related genes in rice. However, treatment of rice plants with methyl jasmonate alleviated disease symptoms caused by RRSV and reduced virus accumulation. Taken together, our results suggest that the induction of miR319 by RRSV infection in rice suppresses JA-mediated defense to facilitate virus infection and symptom development.
Assuntos
Ciclopentanos/metabolismo , MicroRNAs/metabolismo , Oryza/metabolismo , Oryza/virologia , Oxilipinas/metabolismo , Regulação da Expressão Gênica de Plantas , MicroRNAs/genética , Oryza/genética , Doenças das Plantas/genética , Doenças das Plantas/virologia , Vírus de Plantas/patogenicidade , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Plantas Geneticamente Modificadas/virologia , Reoviridae/patogenicidadeRESUMO
Rice stripe virus (RSV) is the type species of the genus Tenuivirus and represents a major viral pathogen affecting rice production in East Asia. In this study, RSV p2 was fused to yellow fluorescent protein (p2-YFP) and expressed in epidermal cells of Nicotiana benthamiana. p2-YFP fluorescence was found to move to the nucleolus initially, but to leave the nucleolus for the cytoplasm forming numerous distinct bright spots there at later time points. A bimolecular fluorescence complementation (BiFC) assay showed that p2 interacted with fibrillarin and that the interaction occurred in the nucleus. Both the nucleolar localization and cytoplasmic distribution of p2-YFP fluorescence were affected in fibrillarin-silenced N. benthamiana. Fibrillarin depletion abolished the systemic movement of RSV, but not that of Tobacco mosaic virus (TMV) and Potato virus X (PVX). A Tobacco rattle virus (TRV)-based virus-induced gene silencing (VIGS) method was used to diminish RSVâ NS2 (encoding p2) or NS3 (encoding p3) during RSV infection. Silencing of NS3 alleviated symptom severity and reduced RSV accumulation, but had no obvious effects on virus movement and the timing of symptom development. However, silencing of NS2 abolished the systemic movement of RSV. The possibility that RSV p2 may recruit or manipulate nucleolar functions to promote virus systemic infection is discussed.
Assuntos
Nucléolo Celular/virologia , Proteínas Cromossômicas não Histona/metabolismo , Proteínas de Plantas/metabolismo , Proteínas dos Retroviridae/metabolismo , Tenuivirus/fisiologia , Nucléolo Celular/metabolismo , Nicotiana/virologiaRESUMO
Plant LRR-RLKs serve as protein interaction platforms, and as regulatory modules of protein activation. Here, we report the isolation of a novel plant-specific LRR-RLK from Glycine soja (termed GsLRPK) by differential screening. GsLRPK expression was cold-inducible and shows Ser/Thr protein kinase activity. Subcellular localization studies using GFP fusion protein indicated that GsLRPK is localized in the plasma membrane. Real-time PCR analysis indicated that temperature, salt, drought, and ABA treatment can alter GsLRPK gene transcription in G. soja. However, just protein induced by cold stress not by salinity and ABA treatment in tobacco was found to possess kinase activity. Furthermore, we found that overexpression of GsLRPK in yeast and Arabidopsis can enhance resistance to cold stress and increase the expression of a number of cold responsive gene markers.