Role of Lytic Enzymes Secreted by Lysobacter capsici YS1215 in the Control of Root-Knot Nematode of Tomato Plants

Lysobacter spp. are well known as biocontrol agents acting against fungal pathogens and root-knot nematode disease, which cause serious losses in a wide range of crops. In this study, the roles of the lytic enzymes from Lysobacter capsici YS1215, isolated from soil in Korea, was investigated for the biocontrol of root-knot nematode under in vitro and in vivo conditions. Chitinase and gelatinase activities of L. capsici YS1215 were enhanced by second stage nematode eggs and juveniles of Meloidogyne incognita into medium as substrates. The activities were confirmed by SDS-PAGE with active bands in chitinase active staining and gelatin zymography. The results clearly indicated that application of bacterial cultures and crab shell powder significantly increased the chitinase and gelatinase activities, as well as the population of chitinolytic and gelatinolytic bacteria in the rhizosphere. Furthermore, L. capsici YS1215 also promoted growth of shoot due to a decrease in the severity of disease caused by M. incognita in comparison with the control (fertilizer treatment). These results demonstrated that L. capsici YS1215 and its lytic enzymes played an important role in the suppression of M. incognita infection, and are likely to provide an alternative to synthetic nematicides used for the control of root-knot nematodes infections in tomato plants.