P-358 - NRPS12, a non-ribosimal peptide synthetase gene unique to Fov4, plays important roles in fungal development and pathogenicity in cotton Fusarium wilt

Fusarium wilt, caused by Fusarium oxysporum f. sp. vasinfectum (Fov), is one of the most destructive early-season cotton diseases worldwide. The recent emergence of the highly virulent Fov race 4 (Fov4) and its aggressiveness have raised significant concerns for the U.S. cotton industry. Secondary metabolites are known to play a critical role in the virulence and adaptability of fungal pathogens in host environments. To investigate these factors, we analyzed the genomes of Fov races 1 and 4 using Fungal antiSMASH and identified a Fov4-specific nonribosomal peptide synthetase (NRPS) gene NRPS12. To investigate its function, we generated NRPS12 knock-out mutant using CRISPR-Cas9 technology. Growth assays revealed that the mutants exhibit significantly attenuated hyphal production on media containing cotton roots as the sole carbon source, increased sensitivity to cell stress agents, as well as lagged spore germination. Furthermore, the mutant exhibited defect in cotton root rot virulence and significant decrease in  Fusaric acid production. GFP-labeled wild-type (WT) and NRPS12 deletion mutant will be used to assess infection progression in cotton roots, which will help further characterize the reduced virulence in NRPS12 mutant. Gene complementation restored the observed defects, confirming that NRPS12 is critical for Fov4 virulence, hyphal development, Fusaric acid production, and stress responses. This study provided a better insight into the role of secondary metabolism in cotton Fusarium wilt pathogenesis by Fov4.