Infectivity of blackgram isolate of Mungbean yellow mosaic India virus on cowpea

Yellow mosaic disease of grain legumes is caused by four virus species under the genus Begomovirus. Mungbean yellow mosaic India virus (MYMIV) is more prevalent in northern India. The blackgram isolate (Bg) of MYMIV is known not to infect cowpea through whitefly inoculation. In the present study, agroinoculation of Bg isolate was performed on three cultivars of cowpea and the results were compared with that of cowpea (Cp) isolate of MYMIV. The Bg isolate was infectious on cowpea, and produced leaf curl symptoms only in cv Pusa Komal. The isolate was replication incompetent as only trace levels of viral replicative forms were detected in all the three cultivars tested. The Cp isolate produced severe leaf curl symptom in cv. Pusa Komal besides the golden mosaic symptoms. Agrobacterium mediated delivery of viral components clearly established that, blackgram isolate is capable of infecting cowpea, and causes atypical leaf curl and not yellow mosaic symptoms.