Adaptation to new hosts shown by the cloned components of Mungbean yellow mosaic India virus causing cowpea golden mosaic in northern India

Abstract

The causal virus of golden mosaic of cowpea in northern India has been identified as a variant of Mungbean yellow mosaic India virus (MYMIV) and designated as MYMIV-[Cp]. MYMIV-[Cp] was transmissible by whitefly (Bemisia tabaci) only to cowpea (Vigna unguiculata), yard long bean (V. unguiculata subsp. sesquipedalis), and French bean (Phaseolus vulgaris) and not to any other leguminous hosts. However, agroinoculation of the cloned DNA A and DNA B components of MYMIV-[Cp] produced systemic symptoms in blackgram (V. mungo), mungbean (V. radiata), and mothbean (V. aconitifolia). The severity of disease symptoms and infectivity rate depended on the genotype tested. The progeny virus of agroinoculated plants was whitefly transmissible between blackgram, mungbean, cowpea, and French bean plants. Though the virus was transmissible to blackgram and produced severe symptoms, very low levels of viral DNA components were seen, indicating only limited adaptation to the host. The work communicated here describes, for the first time, the aetiology of golden mosaic of cowpea in northern India and demonstrates adaptation to new hosts of a cloned virus, through agroinoculation.

Keywords:

• begomoviruses
• legumes
• yellow mosaic viruses
• cowpea
• whitefly
• agroinoculation