Role of RNA Modifications, Especially m6A, in Aflatoxin Biosynthesis of <i>Aspergillus flavus</i>

RNA modifications play key roles in eukaryotes, but the functions in <i>Aspergillus flavus</i> are still unknown. Temperature has been reported previously to be a critical environmental factor that regulates the aflatoxin production of <i>A. flavus</i>, but much remains to be learned about the molecular networks. Here, we demonstrated that 12 kinds of RNA modifications in <i>A. flavus</i> were significantly changed under 29 °C compared to 37 °C incubation; among them, m6A was further verified by a colorimetric method. Then, the transcriptome-wide m6A methylome and m6A-altered genes were comprehensively illuminated through methylated RNA immunoprecipitation sequencing and RNA sequencing, from which 22 differentially methylated and expressed transcripts under 29 °C were screened out. It is especially notable that AFCA_009549, an aflatoxin biosynthetic pathway gene (<i>aflQ</i>), and the m6A methylation of its 332nd adenine in the mRNA significantly affect aflatoxin biosynthesis in <i>A. flavus</i> both on media and crop kernels. The content of sterigmatocystin in both Δ<i>aflQ</i> and <i>aflQ</i>^A332C strains was significantly higher than that in the WT strain. Together, these findings reveal that RNA modifications are associated with secondary metabolite biosynthesis of <i>A. flavus</i>.