Arabidopsis thaliana Genes Associated with Cucumber mosaic virus Virulence and Their Link to Virus Seed Transmission.
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ABSTRACT:
SUBMITTER: Montes N
PROVIDER: S-EPMC8067046 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Taxonomic relationshipsCucumber mosaic virus (CMV) is the type species of the genus Cucumovirus in the family Bromoviridae, which also encompasses the Peanut stunt virus (PSV) and the Tomato aspermy virus (TAV). Nucleotide sequence similarity among these three cucumoviruses is 60%-65%. CMV strains are divided into three subgroups, IA, IB and II, based on the sequence of the 5' untranslated region of the genomic RNA 3. Overall nucleotide sequence similarity among CMV strains is approximately 70%-98%. GEOGRAPHICAL DISTRIBUTION, HOST RANGE AND SYMPTOMATOLOGY: CMV is distributed worldwide, primarily in temperate to tropical climate zones. CMV infects more than 1200 species of 100 plant families, including monocot and dicot plants. Symptoms caused by CMV infection vary with the host species and/or CMV strain, and include mosaic, stunt, chlorosis, dwarfing, leaf malformation and systemic necrosis. CMV disease is spread primarily by aphid transmission in a nonpersistent manner.Physical propertiesIn tobacco sap, the thermal inactivation point of the viral infectivity is approximately 70 °C (10 min), the dilution end-point is approximately 10(-4) and viral infectivity is lost after a few days of exposure to 20 °C. Viral infectivity can be retained in freeze-dried tissues and in the form of virions purified using 5 mm sodium borate, 0.5 mm ethylenediaminetetraacetic acid and 50% glycerol (pH 9.0) at -20 °C. CMV particles are isometric, approximately 28-30 nm in diameter and are composed of 180 capsid subunits arranged in pentamer-hexamer clusters with T= 3 symmetry. The sedimentation coefficient (s(20) ,(w) ) is c. 98 S and the particle weight is (5.8-6.7) × 10(6) Da. The virions contain 18% RNA. The RNA-protein interactions that stabilize the CMV virions are readily disrupted by sodium dodecylsulphate or neutral chloride salts. GENOMIC PROPERTIES: The genomic RNAs are single-stranded messenger sense RNAs with 5' cap and 3' tRNA-like structures containing at least five open reading frames. The viral RNA consists of three genomic RNAs, RNA 1 (c. 3.3 kb), RNA 2 (c. 3.0 kb) and RNA 3 (c. 2.2 kb), and two subgenomic RNAs, RNA 4 (c. 1.0 kb) and RNA 4A (c. 0.7 kb). The 3' untranslated regions are conserved across all viral RNAs. CMV is often accompanied by satellite, noncoding, small, linear RNA that is nonhomologous to the helper CMV.
| S-EPMC6638793 | biostudies-literature
Project description:The genetic basis of plant tolerance to parasites is poorly understood. We have previously shown that tolerance of Arabidopsis thaliana to its pathogen cucumber mosaic virus is achieved through changes in host life-history traits on infection that result in delaying flowering and reallocating resources from vegetative growth to reproduction. In this system we analyse here genetic determinants of tolerance using a recombinant inbred line family derived from a cross of two accessions with extreme phenotypes. Three major quantitative trait loci for tolerance were identified, which co-located with three flowering repressor genes, FLC, FRI, and HUA2. The role of these genes in tolerance was further examined in genotypes carrying functional or nonfunctional alleles. Functional alleles of FLC together with FRI and/or HUA2 were required for both tolerance and resource reallocation from growth to reproduction. Analyses of FLC alleles from wild accessions that differentially modulate flowering time showed that they ranked differently for their effects on tolerance and flowering. These results pinpoint a role of FLC in A. thaliana tolerance to cucmber mosaic virus, which is a novel major finding, as FLC has not been recognized previously to be involved in plant defence. Although tolerance is associated with a delay in flowering that allows resource reallocation, our results indicate that FLC regulates tolerance and flowering initiation by different mechanisms. Thus, we open a new avenue of research on the interplay between defence and development in plants.
| S-EPMC8743021 | biostudies-literature
Project description:It has been proposed that in wild ecosystems viruses are often plant mutualists, whereas agroecosystems favour pathogenicity. We seek evidence for virus pathogenicity in wild ecosystems through the analysis of plant-virus coevolution, which requires a negative effect of infection on the host fitness. We focus on the interaction between Arabidopsis thaliana and Cucumber mosaic virus (CMV), which is significant in nature. We studied the genetic diversity of A. thaliana for two defence traits, resistance and tolerance, to CMV. A set of 185 individuals collected in 76 A. thaliana Iberian wild populations were inoculated with different CMV strains. Resistance was estimated from the level of virus multiplication in infected plants, and tolerance from the effect of infection on host progeny production. Resistance and tolerance to CMV showed substantial genetic variation within and between host populations, and depended on the virus x host genotype interaction, two conditions for coevolution. Resistance and tolerance were co-occurring independent traits that have evolved independently from related life-history traits involved in adaptation to climate. The comparison of the genetic structure for resistance and tolerance with that for neutral traits (QST/FST analyses) indicated that both defence traits are likely under uniform selection. These results strongly suggest that CMV infection selects for defence on A. thaliana populations, and support plant-virus coevolution. Thus, we propose that CMV infection reduces host fitness under the field conditions of the wild A. thaliana populations studied.
| S-EPMC6555541 | biostudies-literature
Project description: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.
| S-EPMC7749747 | biostudies-literature
Project description:The cucumber mosaic virus (CMV) 2a RNA-dependent RNA polymerase protein has an additional function in Arabidopsis thaliana, which is to stimulate feeding deterrence (antixenosis) against aphids. Antixenosis is thought to increase the probability that aphids, after acquiring CMV particles from brief probes of an infected plant's epidermal cells, will be discouraged from settling and instead will spread inoculum to neighbouring plants. The amino acid sequences of 2a proteins encoded by a CMV strain that induces antixenosis in A. thaliana (Fny-CMV) and one that does not (LS-CMV) were compared to identify residues that might determine the triggering of antixenosis. These data were used to design reassortant viruses comprising Fny-CMV RNAs 1 and 3, and recombinant CMV RNA 2 molecules encoding chimeric 2a proteins containing sequences derived from LS-CMV and Fny-CMV. Antixenosis induction was detected by measuring the mean relative growth rate and fecundity of aphids (Myzus persicae) confined on infected and on mock-inoculated plants. An amino acid sequence determining antixenosis induction by CMV was found to reside between 2a protein residues 200 and 300. Subsequent mutant analysis delineated this to residue 237. We conjecture that the Fny-CMV 2a protein valine-237 plays some role in 2a protein-induced antixenosis.
| S-EPMC7411660 | biostudies-literature
Project description:Effector-triggered immunity (ETI) is one of the most studied mechanisms of plant resistance to viruses. During ETI, viral proteins are recognized by specific plant R proteins, which most often trigger a hypersensitive response (HR) involving programmed cell death (PCD) and a restriction of infection in the initially infected sites. However, in some plant-virus interactions, ETI leads to a response in which PCD and virus multiplication are not restricted to the entry sites and spread throughout the plant, leading to systemic necrosis. The host and virus genetic determinants, and the consequences of this response in plant-virus coevolution, are still poorly understood. Here, we identified an allelic version of RCY1-an R protein-as the host genetic determinant of broad-spectrum systemic necrosis induced by cucumber mosaic virus (CMV) infection in the Arabidopsis thaliana Co-1 ecotype. Systemic necrosis reduced virus fitness by shortening the infectious period and limiting virus multiplication; thus, this phenotype could be adaptive for the plant population as a defense against CMV. However, the low frequency (less than 1%) of this phenotype in A. thaliana wild populations argues against this hypothesis. These results expand current knowledge on the resistance mechanisms to virus infections associated with ETI in plants.
| S-EPMC9783004 | biostudies-literature
Project description:Genome sequencing and assembly of two Cucumber mosaic virus isolates of subgroup II
| PRJNA1171380 | ENA
Project description:Identification of the determinants of pathogen reservoir potential is central to understand disease emergence. It has been proposed that host lifespan is one such determinant: short-lived hosts will invest less in costly defenses against pathogens, so that they will be more susceptible to infection, more competent as sources of infection and/or will sustain larger vector populations, thus being effective reservoirs for the infection of long-lived hosts. This hypothesis is sustained by analyses of different hosts of multihost pathogens, but not of different genotypes of the same host species. Here we examined this hypothesis by comparing two genotypes of the plant Arabidopsis thaliana that differ largely both in life-span and in tolerance to its natural pathogen Cucumber mosaic virus (CMV). Experiments with the aphid vector Myzus persicae showed that both genotypes were similarly competent as sources for virus transmission, but the short-lived genotype was more susceptible to infection and was able to sustain larger vector populations. To explore how differences in defense against CMV and its vector relate to reservoir potential, we developed a model that was run for a set of experimentally-determined parameters, and for a realistic range of host plant and vector population densities. Model simulations showed that the less efficient defenses of the short-lived genotype resulted in higher reservoir potential, which in heterogeneous host populations may be balanced by the longer infectious period of the long-lived genotype. This balance was modulated by the demography of both host and vector populations, and by the genetic composition of the host population. Thus, within-species genetic diversity for lifespan and defenses against pathogens will result in polymorphisms for pathogen reservoir potential, which will condition within-population infection dynamics. These results are relevant for a better understanding of host-pathogen co-evolution, and of the dynamics of pathogen emergence.
| S-EPMC4223077 | biostudies-literature
Project description:We have cloned two genes, FIS1 and FIS2, that control both fertilization independent seed development and postpollination embryo development in Arabidopsis. These genes confer female gametophytic phenotypes. FIS2 encodes a protein with a C2H2 zinc-finger motif and three putative nuclear localization signals, indicating that it is likely to be a transcription factor. FIS1 encodes a protein with homology to the Drosophila Polycomb group gene Enhancer-of-zeste and is identical to the recently described Arabidopsis gene MEDEA. FIS1 is a protein with a number of putative functional domains, including the SET domain present in Enhancer-of-zeste-related proteins. Comparison of the position of the lesions in the fis1 and medea mutant alleles indicates that fis1 is a null allele producing a truncated polypeptide lacking all the protein domains whereas the deduced protein from medea lacks only the SET domain. We present a model of the role of FIS1 and FIS2 gene products in seed development.
| S-EPMC15133 | biostudies-literature
Project description:A cucumber mosaic virus isolate, named Ho [CMV(Ho)], was isolated from a symptomless Arabidopsis halleri field sample containing low virus titers. An analysis of CMV(Ho) RNA molecules indicated that the virus isolate, besides the usual cucumovirus tripartite RNA genome, additionally contained defective RNA3 molecules and a satellite RNA. To study the underlying mechanism of the persistent CMV(Ho) infection in perennial A. halleri, infectious cDNA clones were generated for all its genetic elements. CMV, which consists of synthetic transcripts from the infectious tripartite RNA genomes, and designated CMV(Ho)tr, multiplied in A. halleri and annual Arabidopsis thaliana Col-0 to a similar level as the virulent strain CMV(Y), but did not induce any symptoms in them. The response of Col-0 to a series of reassortant CMVs between CMV(Ho)tr and CMV(Y) suggested that the establishment of an asymptomatic phenotype of CMV(Ho) infection was due to the 2b gene of CMV RNA2, but not due to the presence of the defective RNA3 and satellite RNA. The accumulation of CMV(Ho) 2b protein tagged with the FLAG epitope (2b.Ho-FLAG) in 2b.Ho-FLAG-transformed Col-0 did not induce any symptoms, suggesting a 2b-dependent persistency of CMV(Ho)tr infection in Arabidopsis. The 2b protein interacted with Argonaute 4, which is known to regulate the cytosine methylation levels of host genomic DNA. Whole genomic bisulfite sequencing analysis of CMV(Ho)tr- and mock-inoculated Col-0 revealed that cytosine hypomethylation in the promoter regions of 82 genes, including two genes encoding transcriptional regulators (DOF1.7 and CBP1), was induced in response to CMV(Ho)tr infection. Moreover, the increased levels of hypomethylation in the promoter region of both genes, during CMV(Ho)tr infection, were correlated with the up- or down-regulation of their expression. Taken altogether, the results indicate that during persistent CMV(Ho) infection in Arabidopsis, host gene expression may be epigenetically modulated resulting from a 2b-mediated cytosine hypomethylation of host genomic DNA.
| S-EPMC8776717 | biostudies-literature