Biological control of banana wilt disease caused by Fusarium oxyspoum f. sp. Cubense using Streptomyces sp. H4

Abstract Banana Fusarium wilt caused by Fusarium oxyspoum f. sp. cubense (Foc) is one of the most destructive diseases. Foc tropical race 4 (TR4) is threatening the global banana industry and can infect almost all banana cultivars. Until now, there is still a lack of an effective method for controlling fusarium wilt. Application of beneficial microbes is considered as an environmentally sound option to manage phytopathogenic fungi. We previously identified Streptomyces sp. H4 with a strong antifungal activity against Foc TR4. In this study, strain H4 extracts obviously inhibited mycelial growth, spore germination and tube elongation of Foc TR4. Spore germination was completely suppressed by 8 × EC50 of extracts. Cell membrane integrity and ultrastructure of Foc TR4 were destroyed, which was supported by the increase of extracellular conductivity and nucleic acid releasing. In a pot experiment, the fermentation broth of strain H4 significantly decreased the disease index of Foc TR4 and improved the growth of banana seedlings. Hence, Streptomyces sp. H4 will be a potential microbial resource for the biocontrol of banana Fusarium wilt and the promotion of plant growth.