CRISPR-Cas9 Gene Editing and Secondary Metabolite Screening Confirm C16 Biosynthetic Gene Cluster Products as Decalin-Containing Diterpenoid Pyrones.

is a causal organism of Fusarium head blight in cereals and maize. Although a few secondary metabolites produced by are considered disease virulence factors, many molecular products of biosynthetic gene clusters expressed by during infection and their associated role in the disease are unknown. In particular, the predicted meroterpenoid products of the biosynthetic gene cluster historically designated as "C16" are likely associated with pathogenicity. Presented here are the results of CRISPR-Cas9 gene-editing experiments disrupting the polyketide synthase and terpene synthase genes associated with the C16 biosynthetic gene cluster in . Culture medium screening experiments using transformant strains were profiled by UHPLC-HRMS and targeted MS experiments to confirm the associated secondary metabolite products of the C16 biosynthetic gene cluster as the decalin-containing diterpenoid pyrones, FDDP-D and FDDP-E. Both decalin-containing diterpenoid pyrones were confirmed to be produced in wheat heads challenged with in growth chamber trials. The extent to which the C16 biosynthetic gene cluster is dispersed within the genus is discussed along with a proposed role of the FDDPs as pathogen virulence factors.