Defective interfering RNAs and defective viruses associated with multipartite RNA viruses of plants (original) (raw)
Related papers
Phytopathology, 2004
Previously, we demonstrated that Broad bean mottle virus (BBMV), a member of the genus Bromovirus, could accumulate RNA 2-derived defective interfering (DI) RNAs during infection. In this work, we study how host and environmental factors affect the accumulation of DI RNAs. Serial passages of BBMV through selected plant species reveal that, with low-multiplicity inocula, some systemic hosts (Vicia faba, Nicotiana clevelandii, and N. tabacum cv. Samsum) support DI RNA accumulation after the first passage cycle but other hosts (Phaseolus vulgaris, Pisum sativum, and Glycine max) do not. However, several passages with the high-multiplicity inocula can generate DI RNAs in pea plants. Local lesion hosts (Chenopodium quinoa, C. amaranticolor, and C. murale) remain free of the DI RNA components. The size of the de novo-formed DI RNAs depends on the host and on environmental conditions. For instance, broad bean plants cultivated in a greenhouse or in a growth chamber at 20°C accumulated DI R...
Spanish Journal of Agricultural Research, 2008
Defective RNA molecules (D-RNAs) are being studied in several plant RNA virus groups. In the genus Bromovirus, D-RNAs have been described for Broad bean mottle virus (BBMV), they are formed by a single internal deletion in the RNA2 and have been generated de novo by serial passages. In contrast, in Brome mosaic virus (BMV) D-RNAs are generated by a single or double internal deletion in the RNA3 without serial passages in their hosts. In this work the external effects of the host and the growth temperature in the generation and accumulation of D-RNAs in BBMV, BMV and Cowpea chlorotic mottle virus (CCMV) are studied. The BBMV and BMV D-RNAs were generated and accumulated with or without serial passages of the viruses in different hosts and cultivars. Plants grown at 12, 16, 20 and 24°C in a growth chamber and in a greenhouse (22 ± 5°C) generated D-RNAs after being inoculated with virusfree D-RNAs, with and without passages. The D-RNAs observed in BBMV and BMV presented some common characteristics: both were formed de novo after serial passages or without passages, their deletion borders had short repeated and palindrome sequences that favour recombination. In addition, growing inoculated plants at lower temperatures greatly facilitated the generation and accumulation of D-RNAs. The CCMV did not generate defective molecules in cowpea (Vigna unguiculata) and Nicotiana benthamiana plants after several serial passages or without passages. This is the first time that D-RNAs have been generated in BBMV without passages and BMV with serial passages.
Brome mosaic virus defective RNAs generated during infection of barley plants
The Journal of general virology, 1999
Brome mosaic virus (BMV) purified from systemically infected barley leaves 8 weeks post-inoculation (p.i.) contained defective RNAs (D-RNAs). The D-RNAs were detected in total and virion RNAs extracted from infected plants at 8 weeks p.i. or later, but not before, when barley plants had been inoculated with virions either containing or lacking D-RNA. The D-RNAs were derived from genomic RNA3 by double or mainly single deletions in the 3a protein ORF, and formed a heterogeneous population. By using in vitro transcripts of D-RNA synthesized from full-length cDNA clones, the D-RNAs were shown to replicate in a helper virus-dependent manner and to be packaged into virions in barley protoplasts. Subgenomic RNA4 was produced from the D-RNA and the coat protein was also expressed. Existence of the D-RNAs together with BMV genomic RNAs in inoculated protoplasts decreased the accumulation of 3a protein but it had no apparent effect on the accumulation of BMV genomic RNA3 or the coat protein....
Artificial defective interfering RNAs derived from RNA 2 of beet necrotic yellow vein virus
Archives of Virology, 1994
Long internal deletions were introduced into cloned cDNA of beet necrotic yellow vein virus RNAs 1-4 and transcripts containing the deletions were tested for their ability to inhibit replication of viral RNA in Chenopodium quinoa protoplasts and plants. No inhibition was observed with the deletion mutants based on RNAs 1, 3 and 4 but the RNA 2 deletion mutants all provoked a dramatic inhibition of synthesis of viral RNAs 1 and 2.
Molecular Plant-Microbe Interactions, 2005
Recombinant plant viruses have the propensity to remove foreign inserts during replication. This process is virusspecific and occurs in a host-dependent manner. In the present study, we investigated the integrity of foreign inserts in recombinant plant viruses using a model system consisting of Tomato bushy stunt virus (TBSV) and its defective interfering RNA (DI). These were tested in Nicotiana benthamiana plants that were either wild type or transgenic for the green fluorescent protein (GFP) gene. GFP-derived inserts were retained in the recombinant TBSV and DI population that were inoculated onto GFPtransgenic N. benthamiana plants in which silencing of the GFP transgene was initiated, but they were removed from the virus and DIs that were maintained on wild-type plants. A foreign insert derived from an endogenous N. benthamiana gene encoding the H subunit of the magnesium chelatase (NbChlH) was deleted, whereas the fragment of an RNA-dependent RNA polymerase gene (NbRdRP1m) was ...
Archives of Virology, 2003
Spring beauty latent virus (SBLV), a bromovirus, systemically and efficiently infected Arabidopsis thaliana, whereas the well-studied bromoviruses brome mosaic virus (BMV) and cowpea chlorotic mottle virus (CCMV) did not infect and poorly infected A. thaliana, respectively. We constructed biologically active cDNA clones of SBLV genomic RNAs and determined their complete nucleotide sequences. Interestingly, SBLV RNA3 contains both the box B motif in the intercistronic region, as does BMV, and the subgenomic promoter-like sequence in the 5 noncoding region, as does CCMV. Sequence comparisons of SBLV, BMV, CCMV, and broad bean mottle virus demonstrated that SBLV is closely related to BMV and CCMV. * Systemic infection by plant viruses is established via multiple steps. At each step, several viral and host factors are involved in virus multiplication. To elucidate the mechanism of viral infections of plants, many viral factors have been examined, but host factors have not been identified in sufficient detail. The complete genome of Arabidopsis thaliana has been sequenced , and this plant species has been used as a model in many studies including the analysis of plant-microbe interactions .
2009
RNA viruses within a host exist as dynamic distributions of closely related mutants and recombinant genomes. These closely related mutants and recombinant genomes, which are subjected to a continuous process of genetic variation, competition, and selection, act as a unit of selection, termed viral quasispecies. Characterization of mutant spectra within hosts is essential for understanding viral evolution and pathogenesis resulting from the cooperative behavior of viral mutants within viral quasispecies. Furthermore, a detailed analysis of viral variability within hosts is needed to design control strategies, because viral quasispecies are reservoirs of viral variants that potentially can emerge with increased virulence or altered tropism. In this work, we report a detailed analysis of within-host viral populations in 13 field isolates of the bipartite Tomato chlorosis virus (ToCV) (genus Crinivirus, family Closteroviridae). The intraisolate genetic structure was analyzed based on sequencing data for 755 molecular clones distributed in four genomic regions within the RNAdependent RNA polymerase (RNA1) and Hsp70h, CP, and CPm (RNA2) open reading frames. Our results showed that populations of ToCV within a host plant have a heterogeneous and complex genetic structure similar to that described for animal and plant RNA viral quasispecies. Moreover, the structures of these populations clearly differ depending on the RNA segment considered, being more complex for RNA1 (encoding replication-associated proteins) than for RNA2 (encoding encapsidation-, systemic-movement-, and insect transmission-relevant proteins). These results support the idea that, in multicomponent RNA viruses, function can generate profound differences in the genetic structures of the different genomic segments.
Host-Specific Generation and Maintenance of Tomato bushy stunt virus Defective Interfering RNAs
Molecular Plant-Microbe Interactions®, 2004
The accumulation of Tomato bushy stunt virus (TBSV) defective interfering RNAs (DIs) has been observed in several species of plants, but the involvement of host-specific processes and the functional role of DIs are still poorly understood. In this study, the accumulation of DIs was compared after several passages of TBSV through Nicotiana benthamiana and pepper (Capsicum annuum). As anticipated, passages of wild-type TBSV through N. benthamiana resulted in the accumulation of significant levels of TBSV DIs, which caused symptom attenuation and prevented the plants from lethal necrosis. On the contrary, TBSV infection of pepper plants caused severe local and systemic chlorosis, but continuous virus passages did not result in detectable levels of DIs accumulation. In addition, the inoculation of pepper plants with a mixture of helper virus and DI either from in vitro generated transcripts or from infected N. benthamiana did not yield DI in upper pepper leaves. Our cumulative results s...