-Secreted Fluvirucin B6 as a Potential Bio-Fungicide for Managing Banana Wilt and Mycotoxins and Modulating the Soil Microbial Community Structure.

Banana wilt caused by f. sp. ( TR4) is the most destructive soil-borne fungal disease. Until now, there has been a lack of effective measures to control the disease. It is urgent to explore biocontrol agents to control TR4 and the secretion of mycotoxin. In this study, fluvirucin B6 was screened from using an activity-guided method. Fluvirucin B6 exhibited strong antifungal activity against TR4 (0.084 mM of EC value) and significantly inhibited mycelial growth and spore germination. Further studies demonstrated that fluvirucin B6 could cause the functional loss of mitochondria, the disorder of metabolism of TR4 cells, and the decrease of enzyme activities in the tricarboxylic acid cycle and electron transport chain, ultimately inhibiting mycotoxin metabolism. In a pot experiment, the application of fluvirucin B6 significantly decreased the incidence of banana wilt and the amount of TR4 and controlled fungal toxins in the soil. Additionally, fluvirucin B6 could positively regulate the changes in the structure of the banana rhizosphere microbial community, significantly enriching beneficial microbes associated with disease resistance. In summary, this study identifies fluvirucin B6, which plays versatile roles in managing fungal diseases and mycotoxins.