Author
FOUNTAIN, JAKE - University Of Georgia | |
BAJAJ, PRASAD - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India | |
PANDEY, MANISH - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India | |
NAYAK, SPURTHI - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India | |
YANG, LIMING - University Of Georgia | |
KUMAR, VINAY - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India | |
JAYALE, ASHWIN - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India | |
CHITIKINENI, ANU - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India | |
ZHUANG, WEIJIANG - Fujian Academy | |
Scully, Brian | |
LEE, R - University Of Georgia | |
KEMERAIT, ROBERT - University Of Georgia | |
VARSHNEY, RAJEEV - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India | |
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. |