Biocontrol potential and antifungal mechanism of Streptomyces angustmyceticus GD7-29 against Fusarium oxysporum f. sp. cubense tropical race 4.

Fusarium wilt of banana, especially caused by Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), is the most devastating disease limiting global banana production. With no effective chemical control and only limited resistant cultivars available, sustainable alternatives are urgently needed. Biocontrol is increasingly considered as an environmentally friendly strategy for managing this disease. In this study, an antagonistic strain, designated GD7-29, was isolated from healthy banana rhizosphere and identified as Streptomyces angustmyceticus based on its morphological, physiological, biochemical, and molecular characteristics. The strain exhibited 70.1% inhibition against Foc TR4 and exhibited broad-spectrum antifungal activity. In pot experiments, GD7-29 achieved 50.8% biocontrol efficacy against Fusarium wilt and promoted plant growth through potassium and phosphate solubilization, protease production, and siderophore production. Genomic analysis revealed 33 biosynthetic gene clusters and multiple functional genes potentially associated with its biocontrol activity. Both the culture supernatant and volatile organic compounds (VOCs) produced by GD7-29 markedly suppressed Foc TR4. Metabolomic profiling identified 1409 differentially abundant metabolites and revealed an enrichment of secondary metabolites. GC-MS analysis detected five VOCs, among which butanoic acid was identified as a compound exhibiting both antifungal and plant growth-promoting activities in subsequent bioassays. Furthermore, GD7-29 upregulated the expression of defense-related genes in banana. This study suggests that S. angustmyceticus may represent a promising biocontrol agent for sustainable management of Fusarium wilt in banana production.