Methyl 2-methylbutyrate produced by Streptomyces saccharicans strain ZBY1-20 inhibits Monilinia fructicola causing peach brown rot

• S. saccharicans ZBY1-20 produces methyl 2-methylbutyrate to inhibit M. fructicola . • Methyl 2-methylbutyrate has surprising efficacy in inhibiting M. fructicola . • Methyl 2-methylbutyrate affects the ribosome-related pathway of M. fructicola . Postharvest peach brown rot disease, predominantly caused by Monilinia fructicola , leads to significant economic losses, with up to 50 % fruit rot. Current control strategies rely heavily on chemical fungicides, raising concerns about pathogen resistance, environmental impact, and pesticide residues. This study explored the potential of volatile metabolites produced by 27 Actinomycetes strains to inhibit M. fructicola . Among them, volatiles from Streptomyces saccharicans strain ZBY1-20 demonstrated limited direct inhibition of brown rot on peaches but effectively suppressed M. fructicola spore germination, suggesting the presence of germination-inhibiting compounds. Comprehensive characterization of ZBY1-20 included BIOLOG phenotypic profiling and physiological assessments. Gas chromatography-mass spectrometry (GC–MS) identified 20 volatile metabolites during a 14-day incubation period, dominated by alcohols, organic acid esters, and terpenes. Methyl 2-methylbutyrate, comprising 5.291 % of the total volatiles, exhibited potent antifungal activity, significantly inhibiting M. fructicola growth and spore production. Notably, 0.1200 ng L -1 of methyl 2-methylbutyrate completely suppressed spore germination and reduced lesion expansion on peach fruit without causing adverse effects. Transcriptomic analysis revealed that methyl 2-methylbutyrate altered M. fructicola gene expression, disrupting ribosome-associated pathways and impairing protein translation. Overall, these findings highlight the efficacy of S. saccharicans strain ZBY1-20 in managing peach brown rot via the production of methyl 2-methylbutyrate, providing an environmentally friendly alternative for postharvest disease control and advancing strategies for fruit preservation.