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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Food and Feed Safety Research » Research » Publications at this Location » Publication #346315

Research Project: Genetic and Environmental Factors Controlling Aflatoxin Biosynthesis

Location: Food and Feed Safety Research

Title: Whole genome comparison of Aspergillus flavus L-morphotype strain NRRL 3357 (type) and S-morphotype strain AF70

Author
item Gilbert, Matthew
item Mack, Brian
item Moore, Geromy
item Downey, Darlene
item Lebar, Matthew
item Joarder, Vinita - J Craig Venter Institute
item Losada, Liliana - J Craig Venter Institute
item Yu, Jiujiang
item Nierman, William - J Craig Venter Institute
item Bhatnagar, Deepak

Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2018
Publication Date: 7/2/2018
Citation: Gilbert, M.K., Mack, B.M., Moore, G.G., Downey, D.L., Lebar, M.D., Joarder, V., Losada, L., Yu, J., Nierman, W.C., Bhatnagar, D. 2018. Whole genome comparison of Aspergillus flavus L-morphotype strain NRRL 3357 (type) and S-morphotype strain AF70. PLoS One. 13(7):e0199169. https://doi.org/10.1371/journal.pone.0199169.
DOI: https://doi.org/10.1371/journal.pone.0199169

Interpretive Summary: Aspergillus flavus is a fungus that infects corn, peanuts, tree nuts and other agriculturally important crops. Once the crop is infected the fungus has the potential to secrete toxins, the most carcinogenic of which is aflatoxin. Aflatoxin contaminated crops are deemed unfit for human or animal consumption, which results in both food and economic losses. Here we report on our success at determining the full genomic sequence (DNA sequence) of a particular strain of A. flavus that produces large amounts of toxins (strain AF70). We also conduct an in-depth analysis of this genome, and compare several key characteristics to another, well established A. flavus strain, NRRL 3357. We analyze the clustering of genes that are responsible for the synthesis of potentially toxic metabolites, and identify genetic mutations, called SNP's, that may account for many of the differences observed between the strains. The goal is to identify genetic sequences that could be targeted by technologies aimed at reducing A. flavus contamination of food and feed crops.

Technical Abstract: Aspergillus flavus is a saprophytic fungus that infects corn, peanuts, tree nuts and other agriculturally important crops. Once the crop is infected the fungus has the potential to secrete one or more mycotoxins, the most carcinogenic of which is aflatoxin. Aflatoxin contaminated crops are deemed unfit for human or animal consumption, which results in both food and economic losses. Within A. flavus, two morphotypes exist: the S strains (small sclerotia) and L strains (large sclerotia). Significant morphological and physiological differences exist between the two morphotypes. For example, the S-morphotypes produces sclerotia that are smaller (< 400 µm), greater in quantity, and contain higher concentrations of aflatoxin than the L-morphotypes. The morphotypess also differ in pigmentation, pH homeostasis in culture and the number of conidiophores produced. Here we report the first full genome sequence of an A. flavus S morphotype, strain AF70. We provide a comprehensive comparison of the A. flavus S-morphotype genome sequence with a previously sequenced genome of an L-morphotype strain (NRRL 3357), including an in-depth analysis of secondary metabolic clusters and the identification SNPs within their aflatoxin gene clusters.