Forty-eight accessions of wild Vigna species/sub-species were grown to verify their reactions to yellow mosaic disease (YMD), under field conditions in New Delhi (India) during 2012 and 2013. Symptoms of YMD that developed on wild Vigna were similar to those observed on cultivated species. Symptomatic plants produced few flowers and pods with reduced seed size. The infection coefficient was in the range of 0–71%. The causal virus was identified by PCR using species-specific primers to detect all the four viruses responsible for YMD in pulse crops. All the YMD-affected wild Vigna species/sub-species accessions were infected by Mungbean yellow mosaic India virus (MYMIV), with positive amplification of the targeted DNA fragment, except one accession of V. hainiana (IC331450) which was infected with Mungbean yellow mosaic virus. This indicated that MYMIV is the predominant virus causing yellow mosaic in wild species/sub-species of Vigna at New Delhi. Eight accessions belonging to V. synthetic allotetraploid, V. umbellata, V. mungo var. mungo, V. trilobata, V. trinervia var. bourneae, V. radiata var. sublobata and V. dalzelliana were completely free from YMD and gave negative PCR results with primers specific to all the four viruses. This confirms resistance to YMD in these wild Vigna species.
Mungbean yellow mosaic virus; Mungbean yellow mosaic India virus