Multifaceted biocontrol mechanisms of Bacillus amyloliquefaciens F028 against Botrytis cinerea in postharvest tomato fruit.

Tomato gray mold, caused by Botrytis cinerea, results in significant postharvest losses, necessitating the development of environmentally friendly biocontrol strategies. This study isolated Bacillus amyloliquefaciens strain F028 from tomato rhizosphere and evaluated its biocontrol potential and underlying mechanisms against gray mold. Strain F028 exhibited strong in vitro antagonism against B. cinerea, causing plasma membrane damage. Whole-genome sequencing revealed multiple biosynthetic gene clusters for antimicrobial compounds. In vivo assays on tomato fruit demonstrated that F028 significantly reduced lesion development and pathogen colonization. Molecular analyses indicated that F028 downregulated key fungal virulence genes and activated host defense responses, including upregulation of salicylic acid and jasmonic acid-pathway genes and enhanced antioxidant enzyme activities. Furthermore, volatile organic compounds (VOCs) emitted by F028 strongly inhibited B. cinerea growth both in vitro and on fruit. GC-MS analysis identified 26 VOCs, with 2-undecanol and 2-decanol showing the highest antifungal activity. In conclusion, B. amyloliquefaciens F028 controls gray mold through a multi-layered strategy involving direct antifungal activity, suppression of pathogen virulence, induction of host immunity, and VOC-mediated inhibition, highlighting its promise as a sustainable biocontrol agent.