Abstract
Aspergillus flavus is an opportunistic pathogen of plants such as maize and peanut under conducive conditions such as drought stress resulting in significant aflatoxin production. Drought-associated oxidative stress also exacerbates 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 and targets for host resistance breeding. Three isolates, AF13, NRRL3357, and K54A with high, moderate, and no aflatoxin production, were cultured in medium supplemented with varying levels of H2O2, and examined using an iTRAQ (Isobaric Tags for Relative and Absolute Quantification) approach. Overall, 1,173 proteins were identified and 220 were 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 oxidative stress tolerance, likely assisting in plant infection and microbial competition. Elevated expression of energy and cellular component production in NRRL3357 and K54A implies a focus on oxidative damage remediation. These trends explain isolate-to-isolate variation in oxidative stress tolerance and provide insights into mechanisms relevant to host plant interactions under drought stress allowing for more targeted efforts in host resistance research.
Highlights
Aspergillus flavus (Link ex Fr, Teleomorph: Petromyces flavus) is a facultative plant pathogen, which is capable of infecting maize and peanut
Given that drought stress is one of the primary predisposing factors contributing to aflatoxin contamination, understanding the interaction between host plants and A. flavus and other aflatoxigenic species is important for developing novel avenues of enhancing host resistance
In order to examine the differences in the responses of highly toxigenic, moderately toxigenic, and atoxigenic isolates of A. flavus to oxidative stress as encountered in the field during drought stress and the colonization of stressed host plant tissues, a comparative proteomic analysis was performed on select isolates following treatment with various levels of H2O2
Summary
Aspergillus flavus (Link ex Fr, Teleomorph: Petromyces flavus) is a facultative plant pathogen, which is capable of infecting maize and peanut. Given the evident relationship between oxidative stress and aflatoxin production in A. flavus and related Aspergillus spp., and the potential role of oxidative stress and ROS in communication between this pathogen and its hosts under drought stress, investigating the influence of oxidative stress on A. flavus may provide insights into the cause of exacerbated aflatoxin contamination under drought and novel means of preventing it. To begin investigating this possibility, we previously examined the transcriptomes of several field isolates of A. flavus to oxidative stress when utilizing both aflatoxin conducive or non-conducive substrates[30,31]. Post-transcriptional modifications have been suggested based on the low correlation between their RNA sequencing gene expression levels and observed fold-changes in proteins, such as in the case of A. flavus responses to temperature stress[34]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
