Occurrence of endogenous Piper yellow mottle virus in black pepper.

Some badnaviruses are known to occur as endogenous viruses integrated into their host genome. In the present study, Piper yellow mottle virus (PYMoV), a badnavirus infecting black pepper was shown to occur as endogenous virus based on the PCR, reverse transcription (RT)-PCR, ELISA and Southern hybridization tests. Black pepper plants that tested positive in PCR for PYMoV gave negative reaction in RT-PCR indicating that they harbour endogenous PYMoV (ePYMoV) sequences. The RT-PCR (-ve) plants tested negative in ELISA and also in PCR using outword primers to amplify the full circular genome. Further, the presence of ePYMoV sequences in the black pepper genome was confirmed by Southern hybridization analysis using cloned PYMoV genomic fragments as probes. Among different open reading frames (ORFs) of the virus, ORF 3 was more frequently integrated. This is the first report of occurrence of ePYMoV sequences in black pepper genome.