Biocontrol Efficacy of a Seed-Derived Streptomyces pseudogriseolus YTU-S40 Against White Rot in Postharvest Grapes

Grape white rot, a fungal disease caused by Coniella diplodiella, leads to the decay and abscission of leaves and fruits. This disease is recognized as one of the major fungal diseases affecting the grape industry, significantly impacting the quality and yield of grapes. In this study, a seed-derived Streptomyces strain with high biocontrol activity, designated YTU-S40, was isolated from the seeds of Cnidium monnieri (L.). Molecular phylogenetic identification revealed that this isolate belongs to Streptomyces pseudogriseolus. In vitro plate confrontation experiments demonstrated that YTU-S40 exhibited a robust inhibition rate of 76.2% against C. diplodiella. Furthermore, this strain exhibited relatively broad-spectrum antifungal activity, and genomic analysis predicted that its genome harbors 21 biosynthetic gene clusters responsible for secondary metabolite production. In vivo postharvest grape biocontrol assays verified that YTU-S40 significantly reduced the incidence of grape white rot from 94.4% to 1.9%. Untargeted metabolomic profiling suggested that YTU-S40 may produce bioactive antifungal compounds such as antimycins. Collectively, these findings suggest that YTU-S40 holds considerable promise for development as a biocontrol agent.