Location: Food and Feed Safety ResearchTitle: Whole genome comparison of Aspergillus flavus L-morphotype strain NRRL 3357 (type) and S-morphotype strain AF70
|JOARDER, VINITA - J Craig Venter Institute|
|LOSADA, LILIANA - J Craig Venter Institute|
|NIERMAN, WILLIAM - J Craig Venter Institute|
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.
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.