Protein–protein interactions and nuclear trafficking of coat protein and βC1 protein associated with Bhendi yellow vein mosaic disease

Bhendi yellow vein mosaic disease (BYVMD) is caused by a complex consisting of a monopartite begomovirus BYVMV and a satellite DNA β component. BYVMV represents a new member of the emerging group of monopartite begomoviruses requiring a satellite component for symptom induction. Here we report the results of the transient expression of green fluorescent protein (GFP) fused with the βC1 and coat protein (CP) coding regions, in the epidermal cells of Nicotiana benthamiana. GFPCP was found to be targeted into the nucleus whereas GFPβC1 was localized towards the periphery of the cell. The sub-cellular localization of the βC1 protein has been compared with that of the CP in yeast cells using a genetic system for detection of protein nuclear import and export. Expression of βC1 ORF in transgenic N. benthamiana under the control of the Cauliflower mosaic virus 35S promoter produced severe developmental abnormalities in the plant, like distorted stem, leaves and stunting of the plant. We also present the results on the interaction of CP and βC1 proteins using yeast two hybrid analysis, suggesting a collaborative role in the inter- and intracellular dynamics of BYVMD.