RESUMO
Drought affects crops directly, and indirectly by affecting the activity of insect pests and the transmitted pathogens. Here, we established an experiment with well-watered or water-stressed melon plants, later single infected with either cucumber mosaic virus (CMV: non-persistent), or cucurbit aphid-borne yellow virus (CABYV: persistent), or both CMV and CABYV, and mock-inoculated control. We tested whether i) the relation between CMV and CABYV is additive, and ii) the relationship between water stress and virus infection is antagonistic, i.e., water stress primes plants for enhanced tolerance to virus infection. Water stress increased leaf greenness and temperature, and reduced leaf water potential, shoot biomass, stem dimensions, rate of flowering, CABYV symptom severity, and marketable fruit yield. Virus infection reduced leaf water potential transiently in single infected plants and persistently until harvest in double-infected plants. Double-virus infection caused the largest and synergistic reduction of marketable fruit yield. The relationship between water regime and virus treatment was additive in 12 out of 15 traits at harvest, with interactions for leaf water content, leaf:stem ratio, and fruit set. We conclude that both virus-virus relations in double infection and virus-drought relations cannot be generalized because they vary with virus, trait, and plant ontogeny.
Assuntos
Cucurbitaceae , Secas , Doenças das Plantas , Doenças das Plantas/virologia , Cucurbitaceae/virologia , Cucumovirus/fisiologia , Cucumovirus/patogenicidade , Folhas de Planta/virologia , Vírus de Plantas/fisiologia , Água/metabolismoRESUMO
Vertical transmission, the transfer of pathogens across generations, is a critical mechanism for the persistence of plant viruses. The transmission mechanisms are diverse, involving direct invasion through the suspensor and virus entry into developing gametes before achieving symplastic isolation. Despite the progress in understanding vertical virus transmission, the environmental factors influencing this process remain largely unexplored. We investigated the complex interplay between vertical transmission of plant viruses and pollination dynamics, focusing on common bean (Phaseolus vulgaris). The intricate relationship between plants and pollinators, especially bees, is essential for global ecosystems and crop productivity. We explored the impact of virus infection on seed transmission rates, with a particular emphasis on bean common mosaic virus (BCMV), bean common mosaic necrosis virus (BCMNV), and cucumber mosaic virus (CMV). Under controlled growth conditions, BCMNV exhibited the highest seed transmission rate, followed by BCMV and CMV. Notably, in the field, bee-pollinated BCMV-infected plants showed a reduced transmission rate compared to self-pollinated plants. This highlights the influence of pollinators on virus transmission dynamics. The findings demonstrate the virus-specific nature of seed transmission and underscore the importance of considering environmental factors, such as pollination, in understanding and managing plant virus spread.
Assuntos
Phaseolus , Doenças das Plantas , Polinização , Animais , Doenças das Plantas/virologia , Abelhas/virologia , Phaseolus/virologia , Sementes/virologia , Transmissão Vertical de Doenças Infecciosas , Cucumovirus/fisiologia , Potyvirus/fisiologiaRESUMO
The cucumber mosaic virus (CMV) 2b protein is a suppressor of plant defenses and a pathogenicity determinant. Amongst the 2b protein's host targets is the RNA silencing factor Argonaute 1 (AGO1), which it binds to and inhibits. In Arabidopsis thaliana, if 2b-induced inhibition of AGO1 is too efficient, it induces reinforcement of antiviral silencing by AGO2 and triggers increased resistance against aphids, CMV's insect vectors. These effects would be deleterious to CMV replication and transmission, respectively, but are moderated by the CMV 1a protein, which sequesters sufficient 2b protein molecules into P-bodies to prevent excessive inhibition of AGO1. Mutant 2b protein variants were generated, and red and green fluorescent protein fusions were used to investigate subcellular colocalization with AGO1 and the 1a protein. The effects of mutations on complex formation with the 1a protein and AGO1 were investigated using bimolecular fluorescence complementation and co-immunoprecipitation assays. Although we found that residues 56-60 influenced the 2b protein's interactions with the 1a protein and AGO1, it appears unlikely that any single residue or sequence domain is solely responsible. In silico predictions of intrinsic disorder within the 2b protein secondary structure were supported by circular dichroism (CD) but not by nuclear magnetic resonance (NMR) spectroscopy. Intrinsic disorder provides a plausible model to explain the 2b protein's ability to interact with AGO1, the 1a protein, and other factors. However, the reasons for the conflicting conclusions provided by CD and NMR must first be resolved.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Proteínas Argonautas , Cucumovirus , Proteínas Argonautas/metabolismo , Proteínas Argonautas/genética , Cucumovirus/metabolismo , Cucumovirus/genética , Cucumovirus/fisiologia , Arabidopsis/metabolismo , Arabidopsis/virologia , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Ligação Proteica , Proteínas Virais/metabolismo , Proteínas Virais/genética , Interações Hospedeiro-Patógeno , Proteínas do Complexo da Replicase Viral/metabolismo , Proteínas do Complexo da Replicase Viral/genética , Doenças das Plantas/virologia , RNA Polimerase Dependente de RNA/metabolismo , RNA Polimerase Dependente de RNA/genética , RNA Polimerase Dependente de RNA/química , MetiltransferasesRESUMO
As a type of parasitic agent, satellite RNAs (satRNAs) rely on cognate helper viruses to achieve their replication and transmission. During the infection of satRNAs, helper virus RNAs serve as templates for synthesizing viral proteins, including the replication proteins essential for satRNA replication. However, the role of non-template functions of helper virus RNAs in satRNA replication remains unexploited. Here we employed the well-studied model that is composed of cucumber mosaic virus (CMV) and its associated satRNA. In the experiments employing the CMV trans-replication system, we observed an unexpected phenomenon the replication proteins of the mild strain LS-CMV exhibited defective in supporting satRNA replication, unlike those of the severe strain Fny-CMV. Independent of translation products, all CMV genomic RNAs could enhance satRNA replication, when combined with the replication proteins of CMV. This enhancement is contingent upon the recruitment and complete replication of helper virus RNAs. Using the method developed for analyzing the satRNA recruitment, we observed a markedly distinct ability of the replication proteins from both CMV strains to recruit the positive-sense satRNA-harboring RNA3 mutant for replication. This is in agreement with the differential ability of both 1a proteins in binding satRNAs in plants. The discrepancies provide a convincing explanation for the variation of the replication proteins of both CMV strains in replicating satRNAs. Taken together, our work provides compelling evidence that the non-template functions of helper virus RNAs create an optimal replication environment to enhance satRNA proliferation.
Assuntos
Cucumovirus , Vírus Auxiliares , RNA Satélite , RNA Viral , Replicação Viral , Vírus Auxiliares/genética , Vírus Auxiliares/fisiologia , Cucumovirus/genética , Cucumovirus/metabolismo , Cucumovirus/fisiologia , RNA Satélite/metabolismo , RNA Satélite/genética , RNA Viral/genética , RNA Viral/metabolismo , Doenças das Plantas/virologia , Nicotiana/virologia , Nicotiana/metabolismo , Nicotiana/genética , Proteínas Virais/metabolismo , Proteínas Virais/genéticaRESUMO
Aphis gossypii (Sternorrhyncha: Aphididae) aphids are vectors of important plant viruses among which cucumber mosaic virus (CMV) and potato virus Y (PVY). Virus-infected plants attract aphid vectors and affect their behavior and growth performance either positively or negatively depending on mode of transmission. Viruses cause changes in the composition and the amount of volatile organic compounds (VOCs) released by the plant that attract aphids. The aphid parasitoid Aphidius colemani (Hymenoptera: Aphelinidae) has been shown to have higher parasitism and survival rates on aphids fed on virus-infected than aphids fed on non-infected plants. We hypothesized that parasitoids distinguish virus-infected plants and are attracted to them regardless of the presence of their aphid hosts. Herein, we examined the attraction of the A. colemani parasitoid to infected pepper plants with each of CMV or PVY without the presence of aphids. The dynamic headspace technique was used to collect VOCs from non-infected and CMV or PVY-infected pepper plants. Identification was performed with gas chromatography-mass spectrometry (GC-MS). The response of the parasitoids on virus-infected vs non-infected pepper plants was tested by Y-tube olfactometer assays. The results revealed that parasitoids displayed a preference to CMV and PVY infected plants compared to those that were not infected.
Assuntos
Afídeos , Cucumovirus , Infecções por Citomegalovirus , Himenópteros , Vírus de Plantas , Compostos Orgânicos Voláteis , Animais , Afídeos/fisiologia , Cucumovirus/fisiologia , Doenças das PlantasRESUMO
The 2b protein (2b) of cucumber mosaic virus (CMV), an RNA-silencing suppressor (RSS), is a major pathogenicity determinant of CMV. 2b is localized in the nucleus and cytoplasm, and its nuclear import is determined by two nuclear localization signals (NLSs); a carrier protein (importin [IMPα]) is predicted to be involved in 2b's nuclear transport. Cytoplasmic 2bs play a role in suppression of RNA silencing by binding to small RNAs and AGO proteins. A putative nuclear export signal (NES) motif was also found in 2b, but has not been proved to function. Here, we identified a leucine-rich motif in 2b's C-terminal half as an NES. We then showed that NES-deficient 2b accumulated abundantly in the nucleus and lost its RSS activity, suggesting that 2b exported from the nucleus can play a role as an RSS. Although two serine residues (S40 and S42) were previously found to be phosphorylated, we also found that an additional phosphorylation site (S28) alone can affect 2b's nuclear localization and RSS activity. Alanine substitution at S28 impaired the IMPα-mediated nuclear/nucleolar localization of 2b, and RSS activity was even stronger compared to wild-type 2b. In a subcellular fractionation assay, phosphorylated 2bs were detected in the nucleus, and comparison of the accumulation levels of nuclear phospho-2b between wild-type 2b and the NES mutant showed a greatly reduced level of the phosphorylated NES mutant in the nucleus, suggesting that 2bs are dephosphorylated in the nucleus and may be translocated to the cytoplasm in a nonphosphorylated form. These results suggest that 2b manipulates its nucleocytoplasmic transport as if it tracks down its targets, small RNAs and AGOs, in the RNA silencing pathway. We infer that 2b's efficient RSS activity is maintained by a balance of phosphorylation and dephosphorylation, which are coupled to importin/exportin-mediated shuttling between the nucleus and cytoplasm.
Assuntos
Transporte Ativo do Núcleo Celular/fisiologia , Cucumovirus/fisiologia , Imunidade Vegetal/fisiologia , Interferência de RNA/fisiologia , Proteínas Virais/metabolismo , Carioferinas/metabolismoRESUMO
The Replication Associated Proteins (RAP-1 and RAP-2) encoded by CMV ORF 1a and ORF 2a are required for the different stages of the viral replication cycle; being multi-functional, they are good inhibitory targets for anti-CMV compounds. As a new perspective for sustainable crop improvement, we investigated the natural plant-based antimicrobial phytoalexins for their anti-CMV potential. Here, we modeled and predicted the functional domains of RAP-1 and RAP-2, docked with a ligand library comprising 128 phytoalexins reported with broad-spectrum activity, determined their binding energies (BEs), molecular interactions, and inhibition constant (Ki), and compared with the reference plant antiviral compounds ribavirin, ningnanmycin, and benzothiadiazole (BTH). Further, the change in Gibb's free energy of binding (ΔG) and the per residue contribution of the selected top-scored ligand molecules was assessed by the prime MM-GBSA approach. Our results revealed RAP-1 as a discontinuous two-domain and RAP-2 as a multi-domain protein. The compounds glyceollidin (9.8 kcal/mol) and moracin D (7.8 kcal/mol) topped the list for RAP-1 and RAP-2 protein targets respectively and also, the lead molecules had energetically more favorable and comparative ΔG values than the top-scored plant antiviral agent ningnanmycin. The evaluation of in vitro toxicity and agrochemical-like properties showed the least toxicity of these anti-CMV compounds. Taken together, our results provide new insights in understanding the inhibitory effects of phytoalexins towards the RAP proteins and could be employed as new promising anti-CMV candidate compounds for their application in agriculture as biopesticides to combat the CMV disease incidence.Communicated by Ramaswamy H. Sarma.
Assuntos
Cucumovirus , Cucumovirus/fisiologia , Fitoalexinas , Antivirais/farmacologia , Ligantes , Simulação por Computador , Simulação de Acoplamento MolecularRESUMO
Cucumber mosaic virus (CMV) often accompanies a short RNA molecule called a satellite RNA (satRNA). When infected with CMV in the presence of Y-satellite RNA (Y-sat), tobacco leaves develop a green mosaic, then turn yellow. Y-sat has been identified in the fields in Japan. Here, we show that the yellow leaf colour preferentially attracts aphids, and that the aphids fed on yellow plants, which harbour Y-sat-derived small RNAs (sRNAs), turn red and subsequently develop wings. In addition, we found that leaf yellowing did not necessarily reduce photosynthesis, and that viral transmission was not greatly affected despite the low viral titer in the Y-sat-infected plants. Y-sat-infected plants can therefore support a sufficient number of aphids to allow for efficient virus transmission. Our results demonstrate that Y-sat directly alters aphid physiology via Y-sat sRNAs to promote wing formation, an unprecedented survival strategy that enables outward spread via the winged insect vector.
Assuntos
Afídeos/genética , Cucumovirus/genética , Proteínas de Insetos/genética , Insetos Vetores/genética , RNA Satélite/genética , RNA Viral/genética , Animais , Afídeos/fisiologia , Afídeos/virologia , Cucumovirus/fisiologia , Regulação da Expressão Gênica , Interações Hospedeiro-Patógeno , Proteínas de Insetos/metabolismo , Insetos Vetores/fisiologia , Insetos Vetores/virologia , Doenças das Plantas/genética , Doenças das Plantas/parasitologia , Doenças das Plantas/virologia , Folhas de Planta/genética , Folhas de Planta/parasitologia , Folhas de Planta/virologia , Plantas Geneticamente Modificadas , RNA Satélite/fisiologia , RNA Viral/fisiologia , Nicotiana/genética , Nicotiana/parasitologia , Nicotiana/virologia , Vírion/genética , Vírion/fisiologia , Replicação Viral/genética , Replicação Viral/fisiologiaRESUMO
Virus-induced gene silencing (VIGS) is a versatile and attractive approach for functional gene characterization in plants. Although several VIGS vectors for maize (Zea mays) have been previously developed, their utilities are limited due to low viral infection efficiency, insert instability, short maintenance of silencing, inadequate inoculation method, or abnormal requirement of growth temperature. Here, we established a Cucumber mosaic virus (CMV)-based VIGS system for efficient maize gene silencing that overcomes many limitations of VIGS currently available for maize. Using two distinct strains, CMV-ZMBJ and CMV-Fny, we generated a pseudorecombinant-chimeric (Pr) CMV. Pr CMV showed high infection efficacy but mild viral symptoms in maize. We then constructed Pr CMV-based vectors for VIGS, dubbed Pr CMV VIGS. Pr CMV VIGS is simply performed by mechanical inoculation of young maize leaves with saps of Pr CMV-infected Nicotiana benthamiana under normal growth conditions. Indeed, suppression of isopentenyl/dimethylallyl diphosphate synthase (ZmIspH) expression by Pr CMV VIGS resulted in non-inoculated leaf bleaching as early as 5 d post-inoculation (dpi) and exhibited constant and efficient systemic silencing over the whole maize growth period up to 105 dpi. Furthermore, utilizing a ligation-independent cloning (LIC) strategy, we developed a modified Pr CMV-LIC VIGS vector, allowing easy gene cloning for high-throughput silencing in maize. Thus, our Pr CMV VIGS system provides a much-improved toolbox to facilitate efficient and long-duration gene silencing for large-scale functional genomics in maize, and our pseudorecombination-chimera combination strategy provides an approach to construct efficient VIGS systems in plants.
Assuntos
Cucumovirus/fisiologia , Inativação Gênica , Genômica , Zea mays/virologia , Quimera , Nicotiana/fisiologiaRESUMO
Land plant genomes carry tens to hundreds of Resistance (R) genes to combat pathogens. The induction of antiviral R-gene-mediated resistance often results in a hypersensitive response (HR), which is characterized by virus containment in the initially infected tissues and programmed cell death (PCD) of the infected cells. Alternatively, systemic HR (SHR) is sometimes observed in certain R gene-virus combinations, such that the virus systemically infects the plant and PCD induction follows the spread of infection, resulting in systemic plant death. SHR has been suggested to be the result of inefficient resistance induction; however, no quantitative comparison has been performed to support this hypothesis. In this study, we report that the average number of viral genomes that establish cell infection decreased by 28.7% and 12.7% upon HR induction by wild-type cucumber mosaic virus and SHR induction by a single-amino acid variant, respectively. These results suggest that a small decrease in the level of resistance induction can change an HR to an SHR. Although SHR appears to be a failure of resistance at the individual level, our simulations imply that suicidal individual death in SHR may function as an antiviral mechanism at the population level, by protecting neighboring uninfected kin plants.
Assuntos
Cucumovirus/fisiologia , Regulação da Expressão Gênica de Plantas , Genes vpr/fisiologia , Nicotiana/virologia , Doenças das Plantas/genética , Cucumovirus/genética , Resistência à Doença/genética , Proteínas de Plantas/genética , Nicotiana/genéticaRESUMO
BACKGROUND: Most plant viruses rely on vectors for their transmission and spread. One of the outstanding biological questions concerning the vector-pathogen-symbiont multi-trophic interactions is the potential involvement of vector symbionts in the virus transmission process. Here, we used a multi-factorial system containing a non-persistent plant virus, cucumber mosaic virus (CMV), its primary vector, green peach aphid, Myzus persicae, and the obligate endosymbiont, Buchnera aphidicola to explore this uncharted territory. RESULTS: Based on our preliminary research, we hypothesized that aphid endosymbiont B. aphidicola can facilitate CMV transmission by modulating plant volatile profiles. Gene expression analyses demonstrated that CMV infection reduced B. aphidicola abundance in M. persicae, in which lower abundance of B. aphidicola was associated with a preference shift in aphids from infected to healthy plants. Volatile profile analyses confirmed that feeding by aphids with lower B. aphidicola titers reduced the production of attractants, while increased the emission of deterrents. As a result, M. persicae changed their feeding preference from infected to healthy plants. CONCLUSIONS: We conclude that CMV infection reduces the B. aphidicola abundance in M. persicae. When viruliferous aphids feed on host plants, dynamic changes in obligate symbionts lead to a shift in plant volatiles from attraction to avoidance, thereby switching insect vector's feeding preference from infected to healthy plants.
Assuntos
Afídeos/virologia , Buchnera/fisiologia , Capsicum/virologia , Cucumovirus/fisiologia , Doenças das Plantas/virologia , Simbiose , Animais , Afídeos/efeitos dos fármacos , Afídeos/microbiologia , Afídeos/fisiologia , Capsicum/microbiologia , Capsicum/parasitologia , Comportamento Alimentar , Interações Hospedeiro-Parasita , Insetos Vetores/fisiologia , Doenças das Plantas/microbiologia , Doenças das Plantas/parasitologia , Rifampina/farmacologia , Compostos Orgânicos Voláteis/metabolismoRESUMO
The vacuole is a unique plant organelle that plays an important role in maintaining cellular homeostasis under various environmental stress conditions. However, the effects of biotic stress on vacuole structure has not been examined using three-dimensional (3D) visualization. Here, we performed 3D electron tomography to compare the ultrastructural changes in the vacuole during infection with different viruses. The 3D models revealed that vacuoles are remodeled in cells infected with cucumber mosaic virus (CMV) or tobacco necrosis virus A Chinese isolate (TNV-AC ), resulting in the formation of spherules at the periphery of the vacuole. These spherules contain neck-like channels that connect their interior with the cytosol. Confocal microscopy of CMV replication proteins 1a and 2a and TNV-AC auxiliary replication protein p23 showed that all of these proteins localize to the tonoplast. Electron microscopy revealed that the expression of these replication proteins alone is sufficient to induce spherule formation on the tonoplast, suggesting that these proteins play prominent roles in inducing vacuolar membrane remodeling. This is the first report of the 3D structures of viral replication factories built on the tonoplasts. These findings contribute to our understanding of vacuole biogenesis under normal conditions and during assembly of plant (+) RNA virus replication complexes.
Assuntos
Imageamento Tridimensional , Membranas Intracelulares/metabolismo , Doenças das Plantas/virologia , Vírus de Plantas/fisiologia , Vacúolos/metabolismo , Cucumovirus/fisiologia , Cucumovirus/ultraestrutura , Tomografia com Microscopia Eletrônica , Membranas Intracelulares/ultraestrutura , Epiderme Vegetal/citologia , Epiderme Vegetal/ultraestrutura , Epiderme Vegetal/virologia , Vírus de Plantas/ultraestrutura , Frações Subcelulares/metabolismo , Nicotiana/citologia , Tombusviridae/fisiologia , Tombusviridae/ultraestrutura , Vacúolos/ultraestrutura , Proteínas Virais/metabolismo , Replicação Viral/fisiologiaRESUMO
Systemic acquired resistance (SAR) is a broad-spectrum disease resistance response that can be induced upon infection from pathogens or by chemical treatment, such as with benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH). SAR involves priming for more robust activation of defence genes upon pathogen attack. Whether priming for SAR would involve components of RNA silencing remained unknown. Here, we show that upon leaf infiltration of water, BTH-primed Arabidopsis thaliana plants accumulate higher amounts of mRNA of ARGONAUTE (AGO)2 and AGO3, key components of RNA silencing. The enhanced AGO2 expression is associated with prior-to-activation trimethylation of lysine 4 in histone H3 and acetylation of histone H3 in the AGO2 promoter and with induced resistance to the yellow strain of cucumber mosaic virus (CMV[Y]). The results suggest that priming A. thaliana for enhanced defence involves modification of histones in the AGO2 promoter that condition AGO2 for enhanced activation, associated with resistance to CMV(Y). Consistently, the fold-reduction in CMV(Y) coat protein accumulation by BTH pretreatment was lower in ago2 than in wild type, pointing to reduced capacity of ago2 to activate BTH-induced CMV(Y) resistance. A role of AGO2 in pathogen-induced SAR is suggested by the enhanced activation of AGO2 after infiltrating systemic leaves of plants expressing a localized hypersensitive response upon CMV(Y) infection. In addition, local inoculation of SAR-inducing Pseudomonas syringae pv. maculicola causes systemic priming for enhanced AGO2 expression. Together our results indicate that defence priming targets the AGO2 component of RNA silencing whose enhanced expression is likely to contribute to SAR.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Proteínas Argonautas/metabolismo , Cucumovirus/fisiologia , Doenças das Plantas/imunologia , Pseudomonas syringae/fisiologia , Arabidopsis/imunologia , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Proteínas Argonautas/genética , Resistência à Doença , Doenças das Plantas/microbiologia , Folhas de Planta/genética , Folhas de Planta/imunologia , Folhas de Planta/microbiologiaAssuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Proteínas de Homeodomínio/genética , Meristema/genética , Brotos de Planta/genética , Arabidopsis/virologia , Cucumovirus/fisiologia , Modelos Genéticos , Doenças das Plantas/genética , Doenças das Plantas/virologiaRESUMO
BACKGROUND: In Raphanus sativus (Japanese radish), strain D8 of cucumber mosaic virus (CMV-D8) establishes a systemic infection and induces mild mosaic on upper, non-inoculated leaves, whereas strain Y of CMV (CMV-Y) causes only a local infection in the inoculated leaves. Here, we further analyzed the specific viral factor(s) of CMV-D8 that is (are) indispensable for systemic infection in Japanese radish. METHODS: To identify which genomic RNA(s) is (are) involved in systemic infection in radish, we carried out a pseudorecombination analysis between CMV-D8 and CMV-Y. With recombination analyses between CMV-D8 and CMV-Y using mutant/recombinant RNA2s, chimeric and point-mutated RNA3s, we identified viral factors that are indispensable for systemic infection. RESULTS: Viral RNA2 and RNA3 of CMV-D8 facilitated efficient virus spread into the upper, non-inoculated plant tissues of radish (cv. Tokinashi), but not those of CMV-Y. Recombinant RNA2s demonstrated that the 2b protein (2b) and the C-terminus of the 2a protein (2a) of CMV-D8 have a crucial role in systemic infection. In addition, we used chimeric and point-mutated RNA3s to that Pro17 and Pro129 in the coat protein (CP) of CMV-D8 are involved in efficient systemic infection and that Ser51 in the 3a protein (3a) of CMV-D8 has positive effects on systemic spread. The results suggested that these viral factors facilitate systemic infection of CMV-D8 in Japanese radish. CONCLUSION: The C-terminal region of 2a, the entire region of 2b, and supplementary function of either Ser51 in 3a or Pro17/Pro 129 in CP confer systemic infectivity on CMV-D8 in radish. These results further elucidate the complex interaction of viral proteins of CMV to complete systemic infection as a host-specific manner.
Assuntos
Cucumovirus/genética , Cucumovirus/fisiologia , Proteínas do Movimento Viral em Plantas/genética , Raphanus/virologia , Proteínas Virais/genética , Doenças das Plantas/virologia , Folhas de Planta/virologia , RNA Viral/genética , Vírus Reordenados/genética , Nicotiana/virologiaRESUMO
BACKGROUND: Plant viruses move through plasmodesmata (PD) to infect new cells. To overcome the PD barrier, plant viruses have developed specific protein(s) to guide their genomic RNAs or DNAs to path through the PD. RESULTS: In the present study, we analyzed the function of Pepper vein yellows virus P4 protein. Our bioinformatic analysis using five commonly used algorithms showed that the P4 protein contains an transmembrane domain, encompassing the amino acid residue 117-138. The subcellular localization of P4 protein was found to target PD and form small punctates near walls. The P4 deletion mutant or the substitution mutant constructed by overlap PCR lost their function to produce punctates near the walls inside the fluorescent loci. The P4-YFP fusion was found to move from cell to cell in infiltrated leaves, and P4 could complement Cucumber mosaic virus movement protein deficiency mutant to move between cells. CONCLUSION: Taking together, we consider that the P4 protein is a movement protein of Pepper vein yellows virus.
Assuntos
Biologia Computacional/métodos , Nicotiana/virologia , Vírus de Plantas/fisiologia , Proteínas Virais/metabolismo , Algoritmos , Cucumovirus/fisiologia , Mutação , Folhas de Planta/virologia , Plasmodesmos/metabolismo , Plasmodesmos/virologia , Domínios Proteicos , Nicotiana/metabolismo , Proteínas Virais/química , Proteínas Virais/genéticaRESUMO
Cucumber mosaic virus (CMV) caused huge agricultural impact on Passiflora edulis. However, the interactions between CMV and P. edulis are poorly unknown, which lead to lack of prevention and control measures. In this study, we identified the infection of CMV in P. edulis through modern small RNA sequencing (sRNA-seq) technology combined with traditional electron microscope and polymerase chain reaction (PCR) methods. We also confirmed CMV infection adversely affected or modulated the contents of phytochemicals and further injured the development of P. edulis; inversely, P. edulis modulated its resistance to CMV stress by increasing the levels of secondary metabolites and the activities of antioxidant enzymes components. This is of significant importance to understand the interaction between virus infection and plant host.
Assuntos
Cucumovirus/fisiologia , Interações Hospedeiro-Patógeno , Passiflora/química , Passiflora/virologia , Compostos Fitoquímicos/química , Doenças das Plantas/virologia , Antioxidantes/química , Antioxidantes/metabolismo , Frutas/virologia , Fenótipo , Compostos Fitoquímicos/análise , Folhas de Planta/virologia , Análise de Sequência de RNARESUMO
In some plant-virus interactions plants show a sign of healing from virus infection, a phenomenon called symptom recovery. It is assumed that the meristem exclusion of the virus is essential to this process. The discovery of RNA silencing provided a possible mechanism to explain meristem exclusion and recovery. Here we show evidence that silencing is not the reason for meristem exclusion in Nicotiana benthamiana plants infected with Cymbidium ringspot virus (CymRSV). Transcriptome analysis followed by in situ hybridization shed light on the changes in gene expression in the shoot apical meristem (SAM) on virus infection. We observed the down-regulation of meristem-specific genes, including WUSCHEL (WUS). However, WUS was not down-regulated in the SAM of plants infected with meristem-invading viruses such as turnip vein-clearing virus (TVCV) and cucumber mosaic virus (CMV). Moreover, there is no connection between loss of meristem function and fast shoot necrosis since TVCV necrotized the shoot while CMV did not. Our findings suggest that the observed transcriptional changes on virus infection in the shoot are key factors in tip necrosis and symptom recovery. We observed a lack of GLYCERALDEHYDE 3-PHOSPHATE DEHYDROGENASE (GAPDH) expression in tissues around the meristem, which likely stops virus replication and spread into the meristem.
Assuntos
Cucumovirus/fisiologia , Regulação da Expressão Gênica de Plantas , Nicotiana/virologia , Doenças das Plantas/virologia , Transcriptoma , Gliceraldeído-3-Fosfato Desidrogenase (Fosforiladora)/metabolismo , Meristema/virologia , Doenças das Plantas/genética , Brotos de Planta , Interferência de RNA , Nicotiana/genética , Nicotiana/metabolismoRESUMO
WRKY transcription factors are key regulators in regulating abiotic or biotic stress response in Arabidopsis. Previous studies showed that WRKY30 expression was induced by oxidative stress treatment, fungal elicitor, SA and ABA. However, functions of WRKY30 on viral defense are not well studied. Here, we found that Arabidopsis WRKY DNA binding protein 30 (WRKY30) plays essential roles in regulating Cucumber mosaic virus (CMV) resistance. The expression of WRKY30 was induced by CMV infection and wrky30 mutant displayed more susceptibility (including higher oxidative damages, induced reactive oxygen species synthesis and more PSII photochemistry compromise), while WRKY30 overexpression plants (WRKY30OX) exhibited more resistance to CMV infection. Moreover BRs-induced CMV tolerance is partly dependent on WRKY30. And WRKY30 expression increased after BL treatment. All these demonstrated that WRKY30 works as a positive regulator in plant CMV resistance process.
Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Cucumovirus/fisiologia , Proteínas de Ligação a DNA/genética , Doenças das Plantas/genética , Fatores de Transcrição/genética , Arabidopsis/virologia , Resistência à Doença , Regulação da Expressão Gênica de Plantas , Interações Hospedeiro-Patógeno , Doenças das Plantas/virologia , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/virologia , Regulação para CimaRESUMO
As a class of parasitic, non-coding RNAs, satellite RNAs (satRNAs) have to compete with their helper virus for limited amounts of viral and/or host resources for efficient replication, by which they usually reduce viral accumulation and symptom expression. Here, we report a cucumber mosaic virus (CMV)-associated satRNA (sat-T1) that ameliorated CMV-induced symptoms, accompanied with a significant reduction in the accumulation of viral genomic RNAs 1 and 2, which encode components of the viral replicase. Intrans replication assays suggest that the reduced accumulation is the outcome of replication competition. The structural basis of sat-T1 responsible for the inhibition of viral RNA accumulation was determined to be a three-way branched secondary structure that contains two biologically important hairpins. One is indispensable for the helper virus inhibition, and the other engages in formation of a tertiary pseudoknot structure that is essential for sat-T1 survival. The secondary structure containing the pseudoknot is the first RNA element with a biological phenotype experimentally identified in CMV satRNAs, and it is structurally conserved in most CMV satRNAs. Thus, this may be a generic method for CMV satRNAs to inhibit the accumulation of the helper virus via the newly-identified RNA structure.