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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #347205
Title: Proteome analysis of Aspergillus flavus isolate-specific responses to oxidative stress in relationship to aflatoxin production capability

Author
item FOUNTAIN, JAKE - University Of Georgia
item KOH, JIN - University Of Florida
item YANG, LIMING - University Of Georgia
item PANDEY, MANISH - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India
item NAYAK, SPURTHI - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India
item BAJAJ, PRASAD - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India
item ZHUANG, WEIJIAN - Fujian Agricultural & Forestry University
item CHEN, ZHI-YUAN - Louisana State University
item KEMERAIT, ROBERT - University Of Georgia
item LEE, R - University Of Georgia
item CHEN, SIXUE - University Of Florida
item VARSHNEY, RAJEEV - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India
item Guo, Baozhu

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2018
Publication Date: 2/21/2018
Citation: Fountain, J.C., Koh, J., Yang, L., Pandey, M.K., Nayak, S.N., Bajaj, P., Zhuang, W., Chen, Z., Kemerait, R.C., Lee, R.D., Chen, S., Varshney, R.K., Guo, B. 2018. Proteome analysis of Aspergillus flavus isolate-specific responses to oxidative stress in relationship to aflatoxin production capability. Scientific Reports. 8:3430. https://doi.org/10.1038/s41598-018-21653-x.
DOI: https://doi.org/10.1038/s41598-018-21653-x

Interpretive Summary: Outbreaks of aflatoxin contamination typically occur in regions prone to drought stress. Recent studies have suggested that these reactive oxygen species (ROS) and their reactive byproducts may influence aflatoxin production. We observed that isolates, which produced higher levels of aflatoxin and possessed greater tolerance to oxidative stress, exhibited less differential gene expression compared to less tolerant, atoxigenic isolates. To examine the oxidative stress responses of Aspergillus flavus at the protein/enzymatic level, we examined the proteomic responses of select field isolates of A. flavus to oxidative stress. Three isolates, AF13, NRRL3357, and K54A with high, moderate, and no aflatoxin production, and cultured in medium supplemented with varying levels of H2O2, were examined using an iTRAQ (Isobaric Tags for Relative and Absolute Quantification) approach. Overall, 1,173 proteins were identified of which 238 were found to be differentially expressed (DEPs). Observed DEPs encompassed metabolic pathways including antioxidants, carbohydrates, pathogenicity, and secondary metabolism. Increased lytic enzyme, secondary metabolite, and developmental pathway expression in AF13 was correlated with increased tolerance to oxidative stress, likely assisting in host plant infection and microbial competition. Elevated expression of energy and cellular component production in NRRL3357 and K54A implies a greater focus on oxidative damage remediation. These trends explain observed isolate-to-isolate variation in oxidative stress tolerance and provide insights into important mechanisms relevant to host plant interactions under drought stress allowing for more targeted efforts in host resistance research.

Technical Abstract: Aspergillus flavus is an opportunistic pathogen that infects host plants such as maize and peanut under conducive conditions such as drought stress resulting in significant aflatoxin production. Drought-associated oxidative stress is known to exacerbate aflatoxin production by A. flavus. The objectives of this study were to use proteomics to provide insights into the pathogen responses to H2O2-derived oxidative stress, and to identify potential biomarkers for fungal infection and targets for host resistance breeding. Three isolates, AF13, NRRL3357, and K54A with high, moderate, and no aflatoxin production, and cultured in medium supplemented with varying levels of H2O2, were examined using an iTRAQ (Isobaric Tags for Relative and Absolute Quantification) approach. Overall, 1,173 proteins were identified of which 238 were found to be differentially expressed (DEPs). Observed DEPs encompassed metabolic pathways including antioxidants, carbohydrates, pathogenicity, and secondary metabolism. Increased lytic enzyme, secondary metabolite, and developmental pathway expression in AF13 was correlated with increased tolerance to oxidative stress, likely assisting in host plant infection and microbial competition. Elevated expression of energy and cellular component production in NRRL3357 and K54A implies a greater focus on oxidative damage remediation. These trends explain observed isolate-to-isolate variation in oxidative stress tolerance and provide insights into important mechanisms relevant to host plant interactions under drought stress allowing for more targeted efforts in host resistance research.