Drought stress and aflatoxin contamination: transcriptional responses of Aspergillus flavusto oxidative stress are related to stress tolerance and aflatoxin production capability uri icon

abstract

  • Oilseed crops such as maize and peanut are staple food cropswhich are vital for global food security. The contamination ofthese crops with carcinogenic aflatoxins during infection by Aspergillusflavus under drought stress conditions is a serious threatto the safety of these commodities. In order to better understandthe role of aflatoxin production in the biology of this pathogenunder environmental stress, a collaborative transcriptome projectwas undertaken to examine the transcriptional responses oftoxigenic and atoxigenic isolates of A. flavus to oxidative stress.Selected isolates were cultured in aflatoxin production-conduciveand non-conducive media amended with varying levels ofH2O2. Isolates which possessed greater tolerance to H2O2stress and aflatoxin production capability exhibited fewer differentiallyexpressed genes (DEGs) than those which possessedless tolerance and lower aflatoxin production. Primary metabolicmechanisms were also stimulated in response to stress alongwith antioxidant enzyme-encoding genes. Genes related tofungal development such as aminobenzoate degradation genesand conidiation regulators were also differentially expressedin response to stress. Secondary metabolite biosynthetic processesalso formed a large component of the isolate responsesto stress including those for aflatoxin, aflatrem, and kojic acid.Co-expression analyses also showed that aflatoxin biosyntheticgene expression along with antioxidant genes were highly correlatedwith toxigenic isolate biomass under variable stresses.These results along with others in the literature suggest that theproduction of these secondary metabolites may provide supplementaloxidative stress alleviation. Additional data validation usingproteomics, metabolomics and whole genome resequencing(WGRS) approaches will also be discussed

publication date

  • 2017