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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #329430

Research Project: Developing Genomic Approaches to Improve Resistance to Diseases and Aflatoxin Contamination in Peanut and Corn

Location: Crop Protection and Management Research

Title: Oxidative stress and carbon metabolism influence Aspergillus flavus transcriptome composition and secondary metabolite production

Author
item Fountain, Jake - University Of Georgia
item Bajaj, Prasad - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India
item Pandey, Manish - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India
item Nayak, Spurthi - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India
item Yang, Liming - University Of Georgia
item Kumar, Vinay - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India
item Jayale, Ashwin - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India
item Chitikineni, Anu - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India
item Zhuang, Weijiang - Fujian Academy
item Scully, Brian
item Lee, R - University Of Georgia
item Kemerait, Robert - University Of Georgia
item Varshney, Rajeev - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India
item Guo, Baozhu

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2016
Publication Date: 12/12/2016
Citation: Fountain, J.C., Bajaj, P., Pandey, M., Nayak, S.N., Yang, L., Kumar, V., Jayale, A.S., Chitikineni, A., Zhuang, W., Scully, B.T., Lee, R.D., Kemerait, R.C., Varshney, R.K., Guo, B. 2016. Oxidative stress and carbon metabolism influence Aspergillus flavus transcriptome composition and secondary metabolite production. Scientific Reports. 6:38747. doi: 101038/srep38747.

Interpretive Summary: The contamination of maize and peanut with aflatoxins, the carcinogenic secondary metabolites of Aspergillus flavus, poses a threat to global food safety of human health concern and potential food security. Maize and peanut are staple food crops throughout the world with 1.02 billion and 45.65 million metric tons of production, respectively, in 2013 (FAOSTAT, 2015). These crops are particularly important in developing countries in Africa and Asia where aflatoxin contamination is most severe (Torres et al. 2014; Andrade and Caldas, 2015). Long term exposure to aflatoxin through contaminated foodstuffs results in a myriad of hepatic diseases including cirrhosis, hepatitis, and hepatocellular carcinoma along with birth defects, immune deficiencies, and acute toxicity (Williams et al. 2004; Kew, 2013).

Technical Abstract: Contamination of crops with aflatoxin is a serious threat to global food safety. Aflatoxin production by Aspergillus flavus has been shown to be exacerbated by drought stress in the field and by oxidative stress in vitro. We examined the transcriptomes of three toxigenic and three atoxigenic isolates of A. flavus in aflatoxin conducive and non-conducive media with varying levels of H2O2 to investigate the relationship of the secondary metabolite production, carbon source, and oxidative stress. We found that toxigenic and atoxigenic isolates employ distinct mechanisms to remediate oxidative damage. Carbon source affected the expression profiles of the isolates. Iron metabolism, monooxygenase activity, and secondary metabolite production appeared to participate in A. flavus oxidative stress responses. The results suggest that aflatoxin and aflatrem biosynthesis may remediate oxidative stress by consuming excess oxygen while kojic acid production may limit iron-mediated non-enzymatic generation of reactive oxygen species (ROS). Together, the production of secondary metabolites might enhance A. flavus stress tolerance in nature and during pathogenesis.