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Research Project: Molecular and Environmental Factors Controlling Aflatoxin Reduction by Non-Toxigenic Aspergillus Strains

Location: Food and Feed Safety Research

Title: Global population structure and adaptive evolution of aflatoxin-producing fungi

item Moore, Geromy
item OLARTE, RODRIGO - University Of Minnesota
item Horn, Bruce
item ELLIOTT, JACALYN - North Carolina State University
item SINGH, RAKHI - North Carolina State University
item O'NEAL, CAROLYN - North Carolina State University
item CARBONE, IGNAZIO - North Carolina State University

Submitted to: Ecology and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2017
Publication Date: 11/8/2017
Citation: Moore, G.G., Olarte, R.A., Horn, B.W., Elliott, J.L., Singh, R., O'Neal, C.J., Carbone, I. 2017. Global population structure and adaptive evolution of aflatoxin-producing fungi. Ecology and Evolution. 7:9179-9191.

Interpretive Summary: Aflatoxins produced by several species in Aspergillus section Flavi are a significant problem in agriculture and a continuous threat to human health. To provide further insights into the biology and global population structure of species in section Flavi, single field populations were sampled from major peanut-growing regions in Georgia (U.S.A.), Australia, Argentina, India and Benin (Africa). This manuscript reports our findings of extensive gene flow, despite geographic separation, among these fungi. We also observed evidence of adaptive evolution for A. flavus S-strains that may be of hybrid origin.

Technical Abstract: We employed interspecific principal component analyses for six different categories (geography, species, precipitation, temperature, aflatoxin chemotype profile, and mating type) and inferred maximum likelihood phylogenies for six combined loci, including two aflatoxin cluster regions (aflM/alfN and aflW/aflX) and four non-cluster regions (amdS, trpC, mfs, and MAT), to investigate barriers to gene flow. We found that populations of A. flavus S in Benin were genetically distinct from all other section Flavi species for the combined loci, which suggests reduced gene flow and genetic isolation of this population. Patterns of trans-speciation observed in the two examined cluster regions, whereby A. flavus S in Benin shares chemotype profiles with A. parasiticus in Australia, suggest a potential hybrid origin for these S strains.