Bean dwarf mosaic virus BV1 protein is a determinant of the hypersensitiveresponse and avirulence in Phaseolus vulgaris

The capacities of the begomoviruses Bean dwarf mosaic virus (BDMV) and Bean golden yellow mosaic virus (BGYMV) to differentially infect certain common bean (Phaseolus vulgaris) cultivars were used to identify viral determinan ts of the hypersensitive response (HR) and avirulence (avr) in BDMV. A seri es of hybrid DNA-B components, containing BDMV and BGYMV sequences, was con structed and coinoculated with BDMV DNA-A (BDMV-A) or BDMVA-green florescen t protein into seedlings of cv, Topcrop (susceptible to BDMV and BGYMV) and the BDMV-resistant cvs, Othello and Black Turtle Soup T-39 (BTS), The BDMV avr determinant, in bean hypocotyl tissue, was mapped to the BDMV BV1 open reading frame and, most likely, to the BV1 protein, The BV1 also was ident ified as the determinant of the HR in Othello, However, the HR was not requ ired for resistance in Othello nor was it associated with BDMV resistance i n BTS. BDMV BV1, a nuclear shuttle protein that mediates viral DNA export f rom the nucleus, represents a new class of viral avr determinant. These res ults are discussed in terms of the relationship between the HR and resistan ce.