Coat protein deletion mutation of Mungbean yellow mosaic India virus (MYMIV)

Mungbean yellow mosaic India virus (MYMIV) causing yellow mosaic disease in grain legumes belongs to the genus Begomovirus of the family Geminiviridae. The virus has a bipartite genome comprising two circular single stranded DNA components (DNA A and DNA B) and is transmitted by the whitefly, Bemisia tabaci Genn. DNA A encodes for coat protein on the viral strand and for replication associated proteins and transcription activator proteins in the complementary strand. The coat protein plays key role in whitefly transmission. In the present communication, the regions in coat protein that govern whitefly transmission and systemic spread were mapped by constructing deletion mutations. Results showed that inoculation with viral constructs having N′ terminal deletion of 75 and 150 amino acids affected systemic spread and pathogenicity in cowpea, mungbean and blackgram plants contrasting to French bean which developed symptoms similar to wild type. Assembly of particles and whitefly transmission were not seen in all the mutations. However there was minimum, six folds increase in viral DNA levels in French bean plants inoculated with N′ terminal deletions.