The involvement of the Type Six Secretion System (T6SS) in the virulence ofRalstonia solanacearumon brinjal

Ralstonia solanacearumis an important soil-borne plant pathogen which causes bacterial wilt in a large number of crops. Bacterial Type Six Secretion System (T6SS) is known to participate in pathogenesis, bacterial interaction and inter-bacterial competition. Contribution of T6SS in the virulence ofR. solanacearumon eggplant (Solanum melongenaL) is studied. In this study, five T6SS gene (ompA, vgrG3, hcp, tssHandtssM) mutants have been developed by insertional mutagenesis and the virulence of the mutants was evaluated on eggplant. In general, the T6SS mutants showed significant reduction of wilt on eggplant.R. solanacearummutant ofompAgene significantly reduced the wilt from day five through day eight in petiole inoculation. In soil drench inoculation,R. solanacearummutant ofvgrG3gene reduced the wilt on eggplant and was significantly different throughout the experimental period. Other mutants, viz.,tssH, tssMandhcp,also reduced the wilt during the initial stages of disease development. This is the first report on the role of T6SS genes,ompA, vgrG3, hcpandtssHon virulence ofR. solanacearum.