Evaluation of Pseudomonas koreensis B17-12 as a potential biological control agent against postharvest diseases of tomato

Pathogenic fungi cause severe postharvest diseases on tomato, which has led to tremendous economic losses. In this study, we isolate 125 antagonistic bacteria from the roots of Fraxinus hupehensis, and screened them for antagonistic activity against Botrytis cinerea, Phytophthora infestans and Alternaria solani. Finally, the strain B17-12 was selected for further experiments. Based on sequence analyses of the 16S rDNA and rpoB genes, strain B17-12 was identified as Pseudomonas koreensis. The strain can produce volatile organic compounds (VOCs) that efficiently inhibit B. cinerea, P. infestans and A. solani, 25 VOCs were identified with solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS), and 7 VOCs had been reported to exhibit antimicrobial activity. P. koreensis B17-12 rapidly colonized on the root of tomato. The genome of B17-12 reveals numerous membrane-related genes and 7 secondary metabolite synthesis gene clusters that are crucial for its biological control properties. The study highlights that B17–12 may be an excellent candidate for biological control of postharvest diseases of tomato blight and gray mold. [Display omitted] •Isolate B17-12 from Fraxinus hupehensis was identified as Pseudomonas koreensis.•The fermentation broth and VOCs of B17-12 showed highest antagonistic activity.•The B17-12 exhibited stable colonization in tomato plants, persisting for at least 29 days.