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

Fountain, J C and Bajaj, P and Pandey, M K and Nayak, S N and Yang, L and Kumar, V and Jayale, A S and Chitikineni, A and Zhuang, W and Scully, B T and Lee, R D and Kemerait, R C and Varshney, R K and Guo, B (2016) Oxidative stress and carbon metabolism influence Aspergillus flavus transcriptome composition and secondary metabolite production. Scientific Reports, 6 (38747). pp. 1-12. ISSN 2045-2322

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Contamination of crops with aflatoxin is a serious global threat to food safety. Aflatoxin production by Aspergillus flavus is exacerbated by drought stress in the field and by oxidative stress in vitro. We examined 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 secondary metabolite production, carbon source, and oxidative stress. We found that toxigenic and atoxigenic isolates employ distinct mechanisms to remediate oxidative damage, and that carbon source affected the isolates’ expression profiles. Iron metabolism, monooxygenases, and secondary metabolism appeared to participate in isolate oxidative responses. The results suggest that aflatoxin and aflatrem biosynthesis may remediate oxidative stress by consuming excess oxygen and that kojic acid production may limit iron-mediated, non-enzymatic generation of reactive oxygen species. Together, secondary metabolite production may enhance A. flavus stress tolerance, and may be reduced by enhancing host plant tissue antioxidant capacity though genetic improvement by breeding selection.

Item Type: Article
Divisions: Research Program : Genetic Gains
CRP: CGIAR Research Program on Grain Legumes
Uncontrolled Keywords: Maize, Peanut, Aflatoxins, Transcriptome sequencing, Atoxigenic isolates, Toxigenic isolates
Subjects: Others > Genetics and Genomics
Depositing User: Mr Ramesh K
Date Deposited: 14 Apr 2017 06:08
Last Modified: 14 Apr 2017 06:08
URI: http://oar.icrisat.org/id/eprint/9963
Official URL: http://dx.doi.org/10.1038/srep38747
Acknowledgement: We thank Billy Wilson, Hui Wang, Xiaohong Guo, and Xiangyun Ji for technical assistance in the laboratory. This work is partially supported by the U.S. Department of Agriculture Agricultural Research Service (USDAARS), the Georgia Agricultural Commodity Commission for Corn, the Georgia Peanut Commission, the Peanut Foundation, and AMCOE (Aflatoxin Mitigation Center of Excellence). This work has been also undertaken as part of the CGIAR Research Program on Grain Legumes and the USAID University Linkages Program between USDA-ARS and ICRISAT. ICRISAT is a member of CGIAR Consortium. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA.
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