Submitted to: Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 4, 2001
Publication Date: N/A
Interpretive Summary: Barley yellow dwarf viruses (BYDVs) cause the most damaging virus disease of cereal crops. These viruses have a single small chromosome that is expressed by mechanisms that are very different from those used for the gene of their host plants. As such, the features of the BYDV life cycle that are unique to the viruses are potential targets for the control of the viruses. In this study, we investigated the effects of small deletion in parts of the BYDV chromosome on virus replication and the synthesis of virus-encoded proteins. We showed that a short region between two genes near the middle of the BYDV chromosome was not needed for gene expression but three similar-sized regions near one end of the chromosome were absolutely required for gene expression and the production of progeny virus. This information will be useful to scientists who are interested in studying the mechanisms of gene expression of BYDVs and devising new methods for virus control.
Technical Abstract: Barley yellow dwarf virus PAV (BYDV-PAV) has a 5.7-kb positive-sense single-stranded RNA genome that contains six open reading frames (ORFs). BYDV-PAV produces three subgenomic RNAs (sgRNAs). The largest of which encodes the coat, 17-kDa, and readthrough proteins from two initiation codons. To investigate the role of intergenic and 3'-proximal noncoding regions (NCRs) in coat protein (CP) expression and BYDV-PAV replication, a full-length infectious cDNA of the RNA genome of an Illinois isolate of BYDV-PAV was constructed downstream of the Cauliflower mosaic virus-35S promoter. Linear DNA molecules of these cDNAs were infectious, expressed the 22-kDa CP, and produced both genomic RNA and sgRNAs in ratios similar to those observed in protoplasts inoculated with viral RNA. The portion of 5' NCR of sgRNA1 between open reading frames (ORFs) 2 and 3 was not required for, but enhanced translation of CP from ORF3. Mutants containing deletions in the NCR downstream of ORF5 failed to replicate in oat protoplasts. These results indicate that an intact 3' NCR is required for BYDV-PAV replication.