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Sci Rep. 2016 Dec 12;6:38747. doi: 10.1038/srep38747.

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

Author information

1
Department of Plant Pathology, University of Georgia, Tifton, GA, USA.
2
USDA-ARS Crop Protection and Management Research Unit, Tifton, GA, USA.
3
International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, India.
4
Fujian Agricultural and Forestry University, Fuzhou, Fujian, China.
5
USDA-ARS US Horticultural Research Laboratory, Fort Pierce, FL, USA.
6
Department of Crop and Soil Sciences, University of Georgia, Tifton, GA, USA.

Abstract

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.

PMID:
27941917
PMCID:
PMC5150527
DOI:
10.1038/srep38747
[Indexed for MEDLINE]
Free PMC Article

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