Molecular identification and genetic diversity of yellow mosaic virus in blackgram

The yellow mosaic disease affected blackgram samples were collected from experimental fields at Tamil Nadu Agricultural University, Coimbatore. Variations were observed in yellow mosaic symptoms. A symptom ranged from minute yellow specks sparsely distributed in the leaf lamina to golden yellow mosaic along with necrotic spots was observed. In a severe case, infected plants showed bleached appearance. The PCR using Mungbean yellow mosaic virus (MYMV) CP (DNAA specific) and MYMV - MP (DNA B specific) primers yielded ~ 1000 and ~ 900 bp band respectively which indicates the presence of MYMV in 47.72% of samples analysed. Interestingly PCR using Mungbean yellow mosaic India virus (MYMIV) NM1/NM2 (DNA A specific) and MYMIV - MP (DNA B specific) primers yielded anticipated amplicons, ~ 970 and ~ 900 bp respectively in 20.45% of the samples. The result indicated the presence of both MYMV and MYMIV in the yellow mosaic disease infected plants. PCR amplicons of yellow mosaic disease affected samples using MYMIV-NM1/NM2 and MYMIV - MP were sequenced. The PCR amplicons of MYMIV-NM1/NM2 primers showed 99% identity with Mungbean yellow mosaic India virus DNA A component (DQ400847) and PCR amplicons of MYMIV-MP primers showed 95% identity with Mungbean yellow mosaic India virus MBB-B31 DNA B component (AY937196). Until now MYMIV has not been reported from South India. The report here is the first of its kind. Emergence of MYMIV in Tamil Nadu consequently breaking down of resistance in elite cultivar is discussed.