Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/16/2006
Publication Date: 4/1/2007
Citation: OBrian, G.R., Georgianna, D.R., Wilkinson, J.R., Yu, J., Abbas, H.K., Bhatnagar, D., Cleveland, T.E., Nierman, W.C., Payne, G.A. 2007. The Effect of Elevated Temperature on Gene Transcription and Aflatoxin Biosynthesis. Mycologia. 99(2):232-239. Interpretive Summary: Aflatoxins are the most potent cancer inducing compounds, and toxic as well. Reduction and elimination of aflatoxin in food and feed is important to our health and to reduce economic losses to farmers due to grain spoilage. Aflatoxin formation is affected by many factors, such as temperature and pH. A systematic study on gene expression in relation to temperature changes is reported here.
Technical Abstract: Aflatoxins are produced optimally between 28-30 C, and production decreases as temperatures approach 37 C. A total of 144 genes were differentially expressed between the two temperatures. Among the 103 genes more highly expressed at 28 C, approximately 25 percent were involved in secondary metabolism and about 30 percent were classified as hypothetical. Genes encoding a catalase and superoxide dismutase were among those more highly expressed at 37 C. As anticipated, we also found that all of the aflatoxin biosynthetic genes were much more highly expressed at 28 C relative to 37 C. Surprisingly, expression of the pathway regulatory genes aflR and aflS, as well as aflR anti-sense, did not differ between the two temperatures. These data indicate that the failure of A. flavus to produce aflatoxin at 37 C is not due to lack of transcription of aflR or aflS.