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ARS Home » Southeast Area » Mississippi State, Mississippi » Crop Science Research Laboratory » Corn Host Plant Resistance Research » Research » Publications at this Location » Publication #322140
Title: Identification and quantification of a toxigenic and non-toxigenic Aspergillus flavus strain in contaminated maize using quantitative real-time PCR

Author
item Mylroie, John
item OZKAN, SEVAL - Mississippi State University
item SHIVAJI, RENUKA - University Of North Carolina
item Windham, Gary
item ALPE, MICHAEL - Winfield Solutions
item Williams, William

Submitted to: Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/28/2015
Publication Date: 1/4/2016
Citation: Mylroie, J.E., Ozkan, S., Shivaji, R., Windham, G.L., Alpe, M., Williams, W.P. 2016. Identification and quantification of a toxigenic and non-toxigenic Aspergillus flavus strain in contaminated maize using quantitative real-time PCR. Toxins. 8(1):15. doi:10.3390/toxins8010015.

Interpretive Summary: Aflatoxins, which are produced by the fungus Aspergillus flavus, are toxic to humans, livestock, and pets. The value of maize (Zea mays) grain is markedly reduced when contaminated with aflatoxin which can result in loses totaling millions of dollars annually. Plant resistance and biological control using non-toxin producing strains of A. flavus are considered effective strategies for reducing aflatoxin accumulation in maize grain. Distinguishing between the toxin and non-toxin producing strains is important in determining the effectiveness of biological control strategies and inter-strain interactions. Using differences found in a gene sequence between a toxigenic (NRRL 3357) and a non-toxigenic (NRRL 21882) strain of A. flavus, we developed a set of DNA primers that allows for the identification and quantification of the toxigenic and non-toxigenic strain of A. flavus. This primer set will allow researchers to better determine how the two fungal strains compete on the maize ear and investigate the interaction between maize and the A. flavus strains. Ultimately, a better understanding of fungal/fungal and fungal/maize interactions will allow for implementation of the best biological control practices and how to effectively pair resistant maize lines with biological control strains to achieve maximum protection from aflatoxin accumulation.

Technical Abstract: Aflatoxins, which are produced by the fungus Aspergillus flavus, are toxic to humans, livestock, and pets. The value of maize (Zea mays) grain is markedly reduced when contaminated with aflatoxin. Plant resistance and biological control using non-toxin producing strains are considered effective strategies for reducing aflatoxin accumulation in maize grain. Distinguishing between the toxin and non-toxin producing strains is important in determining the effectiveness of bio-control strategies and understanding inter-strain interactions. Using polymorphisms found in the fungal rRNA intergenic spacer region (IGS) between a toxigenic (NRRL 3357) and a non-toxigenic (NRRL 21882) strain of A. flavus, we developed a set of primers that allows for the identification and quantification of a toxigenic and non-toxigenic strain of A. flavus using quantitative PCR. This primer set has been used to screen maize grain that was inoculated with the toxigenic A. flavus strain, the non-toxigenic A. flavus, and co-inoculated with both strains, and it has been shown to be effective in both the identification and quantification of both strains. Screening of co-inoculated ears from multiple resistant and susceptible genotypic crosses revealed no significant differences in fungal accumulation of either strain in the field test from 2010 and 2011. This primer set will allow researchers to better determine how the two fungal strains compete on the maize ear and investigate the interaction between maize and the A. flavus strains.