SntB triggers the antioxidant pathways to regulate development and aflatoxin biosynthesis in <i>Aspergillus flavus</i>.

Abstract

The epigenetic reader SntB was identified as an important transcriptional regulator of growth, development, and secondary metabolite synthesis in <i>Aspergillus flavus</i>. However, the underlying molecular mechanism is still unclear. In this study, by gene deletion and complementation, we found SntB is essential for mycelia growth, conidial production, sclerotia formation, aflatoxin synthesis, and host colonization. Chromatin immunoprecipitation sequencing (ChIP-seq) and RNA sequencing (RNA-seq) analysis revealed that SntB played key roles in oxidative stress response of <i>A. flavus</i>, influencing related gene activity, especially <i>catC</i> encoding catalase. SntB regulated the expression activity of <i>catC</i> with or without oxidative stress, and was related to the expression level of the secretory lipase (G4B84_008359). The deletion of <i>catC</i> showed that CatC participated in the regulation of fungal morphogenesis, reactive oxygen species (ROS) level, and aflatoxin production, and that CatC significantly regulated fungal sensitive reaction and AFB1 yield under oxidative stress. Our study revealed the potential machinery that SntB regulated fungal morphogenesis, mycotoxin anabolism, and fungal virulence through the axle of from H3K36me3 modification to fungal virulence and mycotoxin biosynthesis. The results of this study shed light into the SntB-mediated transcript regulation pathways of fungal mycotoxin anabolism and virulence, which provided potential strategy to control the contamination of <i>A. flavus</i> and its aflatoxins.