title: Oxidative stress and carbon metabolism influence Aspergillus flavus transcriptome composition and secondary metabolite production.
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 H2O2to 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.
authors.affiliation: Department of Plant Pathology, University of Georgia, Tifton, GA, USA.|USDA-ARS Crop Protection and Management Research Unit, Tifton, GA, USA.
authors.forename: Jake C
authors.initials: JC
authors.lastname: Fountain
authors.affiliation: International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, India.
authors.forename: Prasad
authors.initials: P
authors.lastname: Bajaj
authors.affiliation: International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, India.
authors.forename: Manish
authors.initials: M
authors.lastname: Pandey
authors.affiliation: International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, India.
authors.forename: Spurthi N
authors.initials: SN
authors.lastname: Nayak
authors.affiliation: Department of Plant Pathology, University of Georgia, Tifton, GA, USA.|USDA-ARS Crop Protection and Management Research Unit, Tifton, GA, USA.
authors.forename: Liming
authors.initials: L
authors.lastname: Yang
authors.affiliation: International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, India.
authors.forename: Vinay
authors.initials: V
authors.lastname: Kumar
authors.affiliation: International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, India.
authors.forename: Ashwin S
authors.initials: AS
authors.lastname: Jayale
authors.affiliation: International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, India.
authors.forename: Anu
authors.initials: A
authors.lastname: Chitikineni
authors.affiliation: Fujian Agricultural and Forestry University, Fuzhou, Fujian, China.
authors.forename: Weijian
authors.initials: W
authors.lastname: Zhuang
authors.affiliation: USDA-ARS US Horticultural Research Laboratory, Fort Pierce, FL, USA.
authors.forename: Brian T
authors.initials: BT
authors.lastname: Scully
authors.affiliation: Department of Crop and Soil Sciences, University of Georgia, Tifton, GA, USA.
authors.forename: R Dewey
authors.initials: RD
authors.lastname: Lee
authors.affiliation: Department of Plant Pathology, University of Georgia, Tifton, GA, USA.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Kemerait
authors.affiliation: International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana, India.
authors.forename: Rajeev K
authors.initials: RK
authors.lastname: Varshney
authors.affiliation: USDA-ARS Crop Protection and Management Research Unit, Tifton, GA, USA.
authors.forename: Baozhu
authors.initials: B
authors.lastname: Guo
mesh_terms: D001231:Aspergillus flavus / Q000235:genetics / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism*; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects*; D059467:Transcriptome / Q000187:drug effects*
chemical_list: D005656:Fungal Proteins; D002244:Carbon; D006861:Hydrogen Peroxide