Molecular detection of bean common mosaic and bean common mosaic necrosis potyviruses and pathogroups.

Partial nucleotide sequences of selected isolates of bean common mosaic virus (BCMV) and bean common mosaic necrosis virus (BCMNV) were determined. Based on these sequences and previously published sequence data, a reverse transcription, polymerase chain reaction (RT-PCR) in combination with restriction endonuclease analyses, was developed for molecular detection of BCMV, BCMNV and some viral pathogroups (PG). Specific detection of the two viruses was accomplished by constructing two virus-specific primer pairs that amplified a PCR product specific for each virus. By application of RT-PCR, four BCMV-PG-V isolates were differentiated from isolates of BCMV pathogroups I, II, IV and VII. Distinction of two BCMNV pathogroups (PG-III and PG-VI) was achieved by restriction enzyme XbaI digestion of BCMNV PCR products. However, no combination of tested restriction enzymes distinguished all five recognized BCMV pathogroups. A primer pair Dts/Uny15 proved to be specific for BCMV pathogroup PG-V. Thus, by a combination of RT-PCR and restriction enzyme analyses, it was possible to differentiate both viruses, two pathogroups of BCMNV, and one pathogroup of BCMV from the others.