Isolation, Characterization, and Effective Biocontrol Agents of Ralstonia solanacearum Causing Tomato Bacterial Wilt in Medog, Tibet

Objective The pathogen causing tomato bacterial wilt in Medog, Tibet was isolated, identified, genetic diversity clarified, and effective biocontrol agents determined.

Method Potential pathogens that caused the bacterial wilt on tomato plants were isolated and purified from the specimens collected in Medog by tissue separation. Specific species were identified based on morphological characteristics and molecular analysis prior to toxicologic classification using the phylotype-specific multiplex PCR (Pmx-PCR), physiological race, and biovar determination. Partial egl sequences were amplified by PCR for phylogenetic analysis to assign sequevars. Inhibitory effects of 5 biocontrol agents against the isolated pathogen were assessed using the agar plate diffusion method (inhibition zone assay).

Result Eight Ralstonia solanacearum strains were isolated from the sampled 6 tomato plants infected with bacterial wilt in Medog. All isolates belonged to Phylotype I, Biovar III, and Sequevar 48. In vitro inhibition tests on the isolate demonstrated significant efficacies of all 5 agents. Of them, Changbairun Microbial Agent showed the largest average inhibition zone diameter that exceeded 19mm.

Conclusion R. solanacearum strains from Medog were isolated, characterized, and population genetic structure defined. An effective biocontrol agent was identified for eco-friendly control of the disease on tomato plants.