1997 Volume 14 Issue 2 Pages 105-110
The bacterial wilt resistant line LNSR-7 of tomato was isolated from self-pollinated progenies of leaf-callus derived regenerants by directly inoculating a bacterial wilt pathogen Pseudomonas solanacearum into injured roots of tested plants. The subsequent self-pollinated progenies of the line were examined for their fruit quality and resistance expression under natural cultivation conditions in a pathogen infested tomato field. During three generations of progenies, the tomato plants showing both the bacterial wilt resistance and the high fruit qualities comparable to the parental cultivar were selected in order to fix commercial characteristics of the line. The stable inheritance of the resistance in the subsequent self-pollinated progenies was further examined by directly inoculating the pathogen into the roots of test plants. Inoculated plants were planted in soil heavily infested with the pathogen to ensure exposure to the pathogen. Under these artificial inoculation conditions, the selected line was shown to be highly resistant to the disease. The resistance mechanism in the line was analyzed by examining multiplication and translocation of the pathogen in planta. The precise monitoring of infection behavior of the pathogen was successfully achieved using the genetically marked P. solanacearum. Consequently the present line LNSR-7 strictly limited secondary multiplication and translocation of the pathogen and suppressed the wilt induction by the pathogen.
