Aspergillus flavus is widely distributed in tropical and subtropical regions and infects various crops, including wheat, maize, and peanuts. It can produce different kinds of mycotoxins, especially aflatoxins (AFs), which cause huge losses in crop quality, safety, and commodity price. AFs are the most toxic and carcinogenic naturally compound, which more than 28% liver cancer cases are related to AFs. Therefore, deciphering the regulatory mechanisms of AFs synthesis and controlling the AFs contamination are extremely essential for us.

Previous studies reported that different levels of AFs were produced by Aspergillus spp. in diverse crop substrates. But the regulatory mechanisms are still unclear. In this study, AFs production were detected in maize, rice, and peanut substrates, and transcriptome and proteome technologies were utilized to discover the regulatory mechanism. We founded that (1) the AFB₁ production in maize and rice media were significantly higher than in peanut media; (2) the initial steps of AFs biosynthesis genes, such as aflA, aflB, aflC, were significantly up-regulated in maize substrate; (3) the genes involved in acetyl-CoA accumulation were upregulated and the genes involved in acetyl-CoA consumption were downregulated, which leaded to the increase of acetyl-CoA level in maize substrate; (4) additionally, obviously up-regulation of amylolysis genes were noticed in maize substrates. Taken all, we deduced that different carbon source in diverse crop substrates, especially starch content, is the most important factor for impacting AFs production. Our results partly reveal the regulatory mechanism of diversity substrates on AFs production at transcriptional and translational levels, and make some contribution for the prevention of AFs contamination.

This research was supported by National Key Research and Development Program (Ministry of Science and Technology) and Science and Technology Innovation Project (Chinese Academy of Agricultural Sciences) was published in Frontier in Microbiology at July, 2020.

Source: https://www.frontiersin.org/articles/10.3389/fmicb.2020.01497/full