Comprehensive analysis of aflatoxin B biosynthesis in Aspergillus flavus via transcriptome-wide mA methylome response to cycloleucine.

Aspergillus flavus and its toxic aflatoxins secondary metabolites contaminate food and grains, posing a severe threat to human health and leading to liver cancer. Here, we demonstrated that cycloleucine blocked aflatoxin B synthesis by inhibiting N-methyladenosine (mA) methylation modification of messenger RNA (mRNA). mA Methylation Immunoprecipitation Sequencing (mA MeRIP-Seq)-based comprehensive transcriptome-wide mA profiling identified 102 differentially expressed genes that underwent mA modification, of which 22 hypermethylated genes were downregulated and 49 hypomethylated genes were upregulated, suggesting a negative correlation between mA methylation and gene expression. Notably, cycloleucine inhibited aflatoxin B production via multiple targets. The mA sites of several key genes involved in the aflatoxin B biosynthesis pathway were significantly enriched in the coding sequence and around the stop codon, resulting in their downregulation. Furthermore, mA methylation on genes related to the aflatoxin B biosynthesis pathway led to reduced mRNA stability. Cycloleucine inhibition of aflatoxin B production highlights its potential as an agent for removing mycotoxins in environmental pollution. ENVIRONMENTAL IMPLICATION: Aflatoxins, highly carcinogenic secondary metabolites produced by Aspergillus flavus, frequently contaminate crops such as peanut, corn, wheat and sesame leading to irreversible loss in the quality and yield of agricultural products and posing serious threats to food safety. Aflatoxins has also been linked to developmental delays and liver cancer in humans. In our study, 'monitoring aflatoxin concentrations and its bioaccumulation in organisms' has been conducted. The results demonstrated that aflatoxin production in A. flavus was completely blocked after cycloleucine treatment. Additionally, we demonstrated that inhibition of aflatoxin was linked to N-methyladenosine methylation of multiple genes in aflatoxin biosynthesis pathway.