2020 Volume 62 Pages 95-99
In this study, we examined the biological control potential of a nonpathogenic Xanthomonas sp. strain 11-100-01 (npX) against bacterial spot of lettuce caused by Xanthomonas axonopodis pv. vitians (Xav.). The results from field trials conducted over 3 consecutive years showed that npX had a significant control efficacy towards Xav on lettuce, which was comparable to that of basic copper sulfate. A re-isolation experiment using a spontaneous rifampicin-resistant mutant strain of npX revealed that it efficiently colonized the lettuce leaves, particularly the wounded sites, for at least 1 week after the spray treatment. Furthermore, the results of the in vitro antagonism assay demonstrated that npX produces antibacterial substances that effectively inhibit the multiplication of Xav. Altogether, our results strongly indicated that npX has the potential to be used as a biological control agent against bacterial spot in lettuce.
