Characterization of the suppressive effects of the biological control strain VAR03-1 of Rhizobium vitis on the virulence of tumorigenic R-vitis

摘要

Rhizobium vitis: strain VAR03-1 is a biological control agent that suppresses grapevine crown gall disease caused by a tumorigenic strain of R. vitis (Ti). Both acetosyringone-induced expression of a virulence gene and the growth of Ti were suppressed in vitro when it was cultivated in the VAR03-1 culture filtrate. These inhibitory effects were reduced by high-temperature treatment or incubation for 72 h. Both activities were detected in the high molecular weight fraction (& 100 kDa) of the filtrate. Our results suggest that the antagonistic effects of VAR03-1 on Ti are mediated by large particle(s) released in the culture media.