BACKGROUND: Fusarium oxysporum f. sp. cubense Tropical Race 4 (Foc TR4) is the causal agent of banana Fusarium wilt, a destructive soil-borne disease. Using antagonistic microorganisms, such as Streptomyces species, offers a promising strategy for controlling fungal diseases. However, their field application is limited by an incomplete understanding of microbe-plant-pathogen interactions. RESULTS: This study shows that the marine-derived Streptomyces malaysiensis WHL7 exhibits strong antagonistic activity against multiple phytopathogenic fungi in vitro, particularly Foc TR4. In pot experiments using natural soil, WHL7 treatment significantly reduced the incidence of Fusarium wilt from 55% in the Foc TR4-inoculated control to 15%. No protective effect was observed in sterilized soil, indicating that its biocontrol efficacy depends on the indigenous microbial community. Integrated metabolomic analysis reveals that WHL7 stimulates the key root secretion of glycerol-3-phosphate (G3P). The compound enriches beneficial Bacillus and Pseudomonas species in the rhizosphere. Compared to the Foc TR4-treated group, exogenous application of G3P reduced Foc TR4 abundance by 73%, inhibited pathogenic infection, and consistently increased the populations of Bacillus and Pseudomonas. These enriched microbes were directly linked with reduced disease severity by inducing systemic ACQUIRED RESISTANCE OF plant. CONCLUSIONS: While S. malaysiensis WHL7 directly suppresses Foc TR4 via antagonistic compounds in vitro, it controls disease in pot experiments indirectly by reshaping the rhizosphere microbiome. This restructuring induces host resistance through a g3p-mediated signaling pathway. the study highlights g3p-mediated priming as a sustainable strategy for managing soil-borne diseases. Video Abstract.
Cai et al. (Sat,) studied this question.