Study on the immune defense response of Epimedium sagittatum induced by Colletotrichum fructicola and its biological control

In agricultural production, Epimedium sagittatum fuels traditional Chinese health products but loses much economic value to anthracnose (Colletotrichum fructicola). This study evaluated yield and quality losses, detected C. fructicola colonization via qPCR, analyzed E. sagittatum’s immune response, and screened endophytic biocontrol bacteria. Results showed C. fructicola HY3–2 caused 7.62 % yield loss and 72.79 % reduction in total content of six bioactive components (p preventive 30.57 %). Genome analysis identified 13 secondary metabolite biosynthetic gene clusters, with fengycin and surfactin confirmed as inhibitory metabolites. This study first identifies icariside I and icariside II as phytoalexins, providing insights into E. sagittatum’s immune mechanisms and guiding anthracnose biocontrol for its standardized production.