Comparative transcriptome analysis of Aspergillus flavus isolates under different oxidative stresses and culture media

Abstract

Aspergillus flavus and aflatoxin contamination in the field are known to be influenced by numerous stress factors, particularly drought and heat stress. However, the purpose of aflatoxin production is unknown. Here, we report transcriptome analyses comprised of 282.6 Gb of sequencing data describing 11,144 of 13,487 (82.6%) annotated A. flavus genes, which provides the gene expression comparisons among different A. flavus isolates and between two culture media, aflatoxin conducive (sucrose) and non-conducive (peptone). We identified genes that are differentially expressed (DEGs) in response to oxidative stress in media with H2O2. Isolates tolerating greater levels of oxidative stress exhibited fewer DEGs in comparison to those with less tolerance (r = -0.6). We found that proteolytic genes were more expressed in the non-conducive medium, while carbohydrate catabolic and glucose transporter genes (e.g. MFS transporters) were more expressed in the conducive medium. Among the observed DEGs, components of polyketide (aflatoxin) and isoprenoid (aflatrem) secondary metabolite production along with kojic acid biosynthesis and monooxygenase genes were prevalent. To our knowledge, this is the first study that explores the molecular responses of different A. flavus isolates to H2O2-induced stress in different culture media. Together, these results demonstrate a potential key role for secondary metabolite production in A. flavus oxidative stress responses