Carbohydrate, glutathione, and polyamine metabolism are central to Aspergillus flavus oxidative stress responses over time

Fountain, J C and Yang, L and Pandey, M K and Bajaj, P and Alexander, D and Chen, S and Kemerait, R C and Varshney, R K and Guo, B (2019) Carbohydrate, glutathione, and polyamine metabolism are central to Aspergillus flavus oxidative stress responses over time. BMC Microbiology (TSI), 19 (1). pp. 1-14. ISSN 1471-2180

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Abstract

Background The primary and secondary metabolites of fungi are critical for adaptation to environmental stresses, host pathogenicity, competition with other microbes, and reproductive fitness. Drought-derived reactive oxygen species (ROS) have been shown to stimulate aflatoxin production and regulate in Aspergillus flavus, and may function in signaling with host plants. Here, we have performed global, untargeted metabolomics to better understand the role of aflatoxin production in oxidative stress responses, and also explore isolate-specific oxidative stress responses over time. Results Two field isolates of A. flavus, AF13 and NRRL3357, possessing high and moderate aflatoxin production, respectively, were cultured in medium with and without supplementation with 15 mM H2O2, and mycelia were collected following 4 and 7 days in culture for global metabolomics. Overall, 389 compounds were described in the analysis which encompassed 9 biological super-pathways and 47 sub-pathways. These metabolites were examined for differential accumulation. Significant differences were observed in both isolates in response to oxidative stress and when comparing sampling time points. Conclusions The moderately high aflatoxin-producing isolate, NRRL3357, showed extensive stimulation of antioxidant mechanisms and pathways including polyamines metabolism, glutathione metabolism, TCA cycle, and lipid metabolism while the highly aflatoxigenic isolate, AF13, showed a less vigorous response to stress. Carbohydrate pathway levels also imply that carbohydrate repression and starvation may influence metabolite accumulation at the later timepoint. Higher conidial oxidative stress tolerance and antioxidant capacity in AF13 compared to NRRL3357, inferred from their metabolomic profiles and growth curves over time, may be connected to aflatoxin production capability and aflatoxin-related antioxidant accumulation. The coincidence of several of the detected metabolites in H2O2-stressed A. flavus and drought-stressed hosts also suggests their potential role in the interaction between these organisms and their use as markers/targets to enhance host resistance through biomarker selection or genetic engineering.

Item Type:	Article
Divisions:	Research Program : Genetic Gains
CRP:	UNSPECIFIED
Uncontrolled Keywords:	Aspergillus flavus, Aflatoxin, Drought stress, Oxidative stress, Metabolomics, Abiotic stresses
Subjects:	Others > Abiotic Stress Others > Aflatoxins
Depositing User:	Mr Ramesh K
Date Deposited:	10 Sep 2019 09:16
Last Modified:	10 Sep 2019 10:56
URI:	http://oar.icrisat.org/id/eprint/11302
Official URL:	https://doi.org/10.1186/s12866-019-1580-x
Projects:	UNSPECIFIED
Funders:	UNSPECIFIED
Acknowledgement:	We would like to thank Billy Wilson and Hui Wang for technical assistance in the laboratory. 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. The USDA is an equal opportunity employer and provider. Funding This work is partially supported by the U.S. Department of Agriculture Agricultural Research Service (USDA-ARS), USDA National Institute for Food and Agriculture (USDA-NIFA), the Georgia Agricultural Commodity Commission for Corn, the National Corn Growers Association Aflatoxin Mitigation Center of Excellence (AMCOE), the Georgia Peanut Commission, and The Peanut Foundation.
Links:	Google Scholar

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