LAUSR

In a survey of experimental and commercial fields in different locations of southwest Nigeria, severe mosaic, vein banding and yellowing were observed on bitter leaf plants (Vernonia amygdalina). RT-PCR carried out using total RNA isolated from infected leaf samples and a pair of potyvirus-specific primers yielded an amplicon (~700 bp) from all symptomatic samples, indicating the presence of a potyvirus infection. The amplicon was cloned and sequenced. Basic local alignment search tool analysis reveals that while the coat protein (CP) gene was more closely related (77%) to that of narcissus yellow stripe virus (NYSV), the amino acid sequence of the present virus isolate was more closely related (80%) to that of Colombian datura virus (CDV). The phylogenetic analysis of the virus sequences with selected potyvirus sequences revealed the closest relationship with jasmine ringspot virus. Based on sequence identity at the nucleic acid and protein levels as well as on phylogenetic analysis, the isolate in this study was considered not to be an isolate of jasmine ringspot virus. This mosaic disease of Vernonia in Nigeria was induced by a new, hitherto uncharacterized potyvirus, tentatively named Vernonia mosaic virus (VeMV).