Documentation of Viruses Infecting Lablab (Lablab purpureus L.) Beans in Tamil Nadu, India

Field surveys were conducted in lablab-bean growing areas of Tamil Nadu to document the occurrence and distribution of virus diseases. Samples collected from lablab bean field showed symptoms like bright yellow mosaic patches and puckering on leaves. The total DNA and RNA were isolated from the symptomatic samples separately. The DNAs were subjected to polymerase chain reaction using Begomovirus universal primers and the positive samples amplified 1200 bp amplicon. Similarly, the isolated RNAs were subjected to reverse transcription PCR using Potyvirus universal primers and which amplified 350 bp in preliminary confirmation of viruses. The amplified products were sequenced and the DNA sequences were compared with the sequences available in the NCBI database and the phylogenetic tree was constructed using Mega 11 software. The occurrence of viruses viz., Bean common mosaic virus (BCMV) and Dolichos yellow mosaic virus (DoYMV) were documented. The results indicated a higher incidence of Begomovirus, DoYMV with a mean incidence of 86 per cent followed by the Potyvirus, BCMV with an incidence of around 70 per cent.