1999 Volume 65 Issue 6 Pages 597-603
Ralstonia solanacearum OE1-1 was transformed with pNP126 carrying a luxCDABE operon of Vibrio fisheri and a promoter region derived from the genomic DNA of Burkholderia glumae. Intensity of bioluminescence from YN5 thus obtained positively correlated with growth of the bacteria from the lag phase to the stationary phase in vitro. In this study, we used the VIM camera equipped with the ARGUS 50 to successively observe bioluminescence and the development of bacterial wilt in singly and doubly grafted tomato plants in various combinations of the resistant LS-89 and the susceptible Oogata-Fukuju. The degree of bacterial growth in the roots and collars was one of the determinants for the induction of bacterial wilt in tomato plants. Resistance of LS-89 resulted from suppression of bacterial proliferation in the roots and stems below the first leaf. In grafted tomato plants using LS-89 as the rootstock, all rootstocks were latently infected with the bacteria. The bacteria were also recovered from susceptible scions even though the plants did not wilt. In some plants, the bacteria proliferated in the susceptible scions. These plants wilted heavily. Taken together, suppression of bacterial proliferation in the roots and the stems below the first leaf of resistant rootstocks affected the bacterial growth in the susceptible scions and quantative control of resistance against development of the disease.