The Gene Deletion Reveals That Patulin Biosynthesis Is Not Related to Conidiation in .

Dissemination and survival of ascomycetes is through asexual spores. The gene encodes a CH-type zinc-finger transcription factor, which is essential for asexual development. causes blue mold disease and is the main source of patulin, a mycotoxin that contaminates apple-based food. A PeΔ deficient strain was generated by homologous recombination. In vivo, suppression of completely blocked the development of conidiophores that takes place after the formation of coremia/synnemata, a required step for the perforation of the apple epicarp. Metabolome analysis displayed that patulin production was enhanced by suppression, explaining a higher in vivo aggressiveness compared to the wild type (WT) strain. No patulin was detected in the synnemata, suggesting that patulin biosynthesis stopped when the fungus exited the apple. In vitro transcriptome analysis of PeΔ unveiled an up-regulated biosynthetic gene cluster (PEXP_073960-PEXP_074060) that shares high similarity with the chaetoglobosin gene cluster of . Metabolome analysis of PeΔ confirmed these observations by unveiling a greater diversity of chaetoglobosin derivatives. We observed that chaetoglobosins A and C were found only in the synnemata, located outside of the apple, whereas other chaetoglobosins were detected in apple flesh, suggesting a spatial-temporal organization of the chaetoglobosin biosynthesis pathway.