Roflamycoin produced by Streptomyces alfalfae is involved in the antagonistic interaction with Fusarium pseudograminearum

Abstract

BACKGROUND Fusarium pseudograminearum is a highly destructive fungal pathogen that threatens the production and quality of wheat and barley worldwide. Controlling this toxin‐producing pathogen is a particularly significant challenge. Streptomyces spp. produce diverse secondary metabolites with promising potential for plant disease management. Therefore, in this study, we evaluated the antifungal activity of roflamycoin, a secondary metabolite produced by Streptomyces alfalfae XN‐04, against F. pseudograminearum. RESULTS Roflamycoin strongly inhibited the mycelial growth of F. pseudograminearum , with an EC 50 value of 2.49 μg/mL. Conidial germination and conidiation were completely inhibited at 1.0 and 2.0 μg/mL, respectively. Scanning and transmission electron microscopy revealed marked morphological and ultrastructural damage to the cell walls and plasma membrane of F. pseudograminearum hyphae and conidia. Fluorescence microscopy combined with different dyes showed that roflamycoin induced reactive oxygen species accumulation and altered mitochondrial membrane potential. Additional analysis showed that roflamycoin destroyed the membrane of hyphae, resulting in exosmosis of cell contents and reduced ergosterol content. Plant infection assays further demonstrated that roflamycoin suppressed disease development on wheat coleoptiles, seedlings, and heads. CONCLUSION These findings provide mechanistic insights into the antifungal activity of roflamycoin and support its potential as a lead compound against F. pseudograminearum . © 2026 Society of Chemical Industry.