Metabolites of Trichoderma longibrachiatum EF5 inhibits soil borne pathogen, Macrophomina phaseolina by triggering amino sugar metabolism

Abstract

An endophytic fungal antagonist Trichoderma longibrachiatum EF5 exhibited biocontrol activity against a soil-borne fungal pathogen Macrophomina phaseolina. Under dual co-culture, T. longibrachiatum EF5 showed 58% inhibition against M. phaseolina. Crude soluble metabolites (SMs) extracted from EF5 exhibited biocontrol activity (61%), which is more significant than the cell-free extract. Dual culture of both T. longibrachiatum EF5 and M. phaseolina displayed entangled mycelial structures and retarded hyphal growth. The metabolites responsible for antibiosis and pathogenic activity profiled through GC-MS revealed a total of 131 SMs from axenic culture and upon the interaction of T. longibrachiatum EF5 and M. phaseolina. Interestingly, potential plant-growth-promoting and antimicrobial compounds such as 1- pentanol, 1-hexanol, myristonyl pantothenate, bisabolol, d-Alanine, and diethyl trisulphide were unique with T. longibrachiatum EF5. Few compounds that were not observed or produced minimally under axenic culture were increased during their interaction (e.g., 1,6-anhydro-á-d-Glucopyranose and 5-heptyl dihydro-2(3H)-Furanone), suggesting antimicrobial action against the pathogen. This study also unraveled the induction of amino sugar metabolism when T. longibrachiatum EF5 interacts with M. phaseolina, which is responsible for colonization and counterfeiting the pathogen. Hence T. longibrachiatum EF5 could be a potential biocontrol agent employed for defense priming and plant growth promotion.

Keywords: Amino sugar metabolism; Biocontrol; Macrophomina phaseolina, GC-MS profiling; Metabolites; Trichoderma longibrachiatum EF5.