A newly isolated high-yield siderophores from Trichoderma viride XZ11-1 with high antifungal activity against Fusarium oxysporum and growth-promoting ability in bananas

Abstract Background: Fusarium wilt of banana, a soil-borne disease caused by Fusarium oxysporum (f.sp.) cubense, particularly the Tropical Race 4 (Foc TR4), severely hinders the progress of the banana industry. Utilizing antagonistic microorganisms to suppress pathogen growth and enhance banana production is seen as a promising strategy for disease management. Results: Strain XZ11-1, exhibiting the highest siderophore production ability, was isolated from the Qixianling Tropical Rainforest in Hainan province, China. Through a combination of colony morphology, physiological and biochemical analysis, as well as a dual-gene analysis of ITS4 and TEF1, the strain was identified as Trichoderma viride. Following optimization of fermentation conditions, strain XZ11-1 produced siderophores with a relative content of 79.45%, identified as both hydroxamate siderophores and carboxylate-type siderophores. Additionally, strain XZ11-1 demonstrated potent antifungal activity against 10 phytopathogenic fungi. Co-cultivation experiments revealed that under iron-limiting conditions, siderophores were the primary factor inhibiting the growth of Foc TR4. Notably, the siderophores produced by strain XZ11-1 exhibited a stimulating effect on maize seed germination and effectively colonized the roots of banana plants. Pot experiments further demonstrated that Trichoderma viride XZ11-1 could suppress the growth of Foc TR4 by competing for iron in the environment through siderophore mediation. Moreover, it could enhance iron absorption by banana plants by secreting siderophores to bind with Fe³⁺ in the environment. Conclusions: Therefore, the high-yield siderophores produced by Trichoderma viride XZ11-1 represent a valuable microbial resource for controlling plant pathogenic fungi and promoting plant growth.