Abstract
Transposon mutation of Xanthomonas campestris pv. vesicatoria (Xcv) was induced by using transposon omegon ($\Omega$)-Km (Tn $\Omega$Km), which was confirmed by resistance to kanamycin (KMr), and nonpathogenic mutants were selected through the inoculation test on pepper plants. The mutagenesis frequency was about 6$\times$10-8, and 53 out of 2,000 Kmr bacterial colonies tested were nonpathogenic to the pepper cultivar Cheung-Hong. Optimum conditions for the Tn $\Omega$Km mutagenesis of Xcv were Luria Bertani (LB) broth medium for culture of Xcv, yeast extract-dextrose-CaCO3 (YDC) agar medium for selection of Tn $\Omega$Km-mediated mutants, and over 1 to 2 in the ratio of the donor (Escherichia coli S17-1 with the plasmid pJFF350 $\Omega$Km) and the recipient (Xcv) in the culture for the mutagenesis. One of the 4 nonpathogenic mutants (WNP1, WNP3, WNP4 and WNP5), which had been reconfirmed through the inoculation on pepper cv. Dabokgun, showed no differences in the production of exoenzymes such as protease and polygalacturonase and extracellular polysaccharides in vitro and the bacterial growth rate from those of the wild type of Xcv.
