Functional characterization of the CfPKS gene in drug resistance and stress responses of Colletotrichum fructicola

Natural rubber is a critical strategic resource with substantial economic value, primarily sourced from rubber trees ( Hevea brasiliensis ). However, rubber tree production is threatened by a range of plant diseases. Colletotrichum spp. are among the most destructive pathogens causing leaf diseases in rubber trees. The widespread emergence of drug-resistant strains, resulting from the prolonged use of chemical agents, has made understanding the mechanisms of drug resistance in pathogenic fungi and developing new therapeutic approaches a major research priority. In this study, the Colletotrichum fructicola HD-1 strain was isolated from the leaves of rubber trees, and transcriptome data, profiled following treatment with the Bacillus velezensis HN-2 n-butanol extract, reveals that the CfPKS gene is implicated in drug resistance. Further analysis showed that deletion of the CfPKS gene led to a reduction in spore yield, a significant increase in chitin and melanin content, and enhanced stability of the fungal cell wall and membrane. Furthermore, the CfPKS gene deletion triggered a stronger autophagic response, with a marked upregulation of autophagy-related gene expression. This study provides valuable insights into the antibacterial mechanisms of B. velezensis biocontrol agents and the drug resistance mechanisms of C. fructicola , laying a theoretical foundation for the biological control of rubber tree anthracnose and further understanding of its drug resistance mechanisms. • CfPKS is linked to drug resistance in Colletotrichum fructicola. • Mutation of CfPKS reduces sporulation in C. fructicola. • CfPKS disruption enhances fungicide tolerance in C. fructicola. • CfPKS mutation promotes chitin and melanin accumulation. • CfPKS mutation induces enhanced autophagy in C. fructicola.