Biological control of Ralstonia wilt in tomato.
T. Yang (1), Q. XUE (2), W. Zhang (1), H. Liu (1), J. Guo (1) (1) Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing 210095, China; (2) Nanjing Agricultural University, Nanjing, PRC PEOPLES REP OF CHINA.
Phytopathology 99:S146

Abstract: Bacterial wilt of tomato caused by Ralstonia solanacearum is a destructive soil-borne disease and a serious threat for agricultural production in Southern China. A screening strategy was developed to assess the potential biocontrol agents (BCA) of this disease from tomato-associated bacteria. We isolated 592 bacterial strains from different microenvironments, and obtained 139 ones according to their antagonistic activity against R. solanacearum and three phytopathogenic fungi (Phytophthora capsici, Pythium ultium, Fusarium oxysporum), their production of hydrolytic enzymes and secondary metabolites. Based on the results of in vitro tests above described, an assessment scheme was developed and 23 isolates were considered as the best candidates. Tomato as host plant was included in the greenhouse experiments in which the biocontrol efficacies, plant growth promotion and colonization capacity of these bacterial isolates were confirmed. These 23 antagonists belong to genus of Bacillus, Serratia, Pantoea, Enterobacter, Erwinia, Citrobacter and Pseudomonas based on the 16S rRNA gene sequences. A good positive correlation coefficient (r = 0.837) between biocontrol efficiency and assessment points verified the feasibility of the assessment scheme. And all 23 antagonists showed the ability to improve the plant growth in the greenhouse. Besides, Pantoea ananatis 1FY7 was the best strain to control Ralstonia wilt of tomato. Thanks to National Natural Science Foundation of China (30800714).