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ARS Home » Southeast Area » Dawson, Georgia » National Peanut Research Laboratory » Research » Publications at this Location » Publication #310482
Title: The origins of aflatoxin chemotype diversity in Aspergillus populations

Author
item CARBONE, I - North Carolina State University
item Horn, Bruce
item OLARTE, R - North Carolina State University
item MOORE, G - North Carolina State University
item WORTHINGTON, C - North Carolina State University
item MONACELL, J - North Carolina State University
item SINGH, R - North Carolina State University
item STONE, E - North Carolina State University
item HELL, K - International Institute For Tropical Agriculture
item CHULZE, S - Universidad Nacional De Cordoba
item BARROS, G - Universidad Nacional De Cordoba
item WRIGHT, G - Department Of Primary Industries
item NAIK, M - College Of Agriculture

Submitted to: International Congress of Plant Pathology Abstracts and Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/2013
Publication Date: 8/1/2013
Citation: Carbone, I., Horn, B.W., Olarte, R.A., Moore, G.G., Worthington, C.J., Monacell, J.T., Singh, R., Stone, E.A., Hell, K., Chulze, S.N., Barros, G., Wright, G.C., Naik, M.K. 2013. The origins of aflatoxin chemotype diversity in Aspergillus populations. International Congress of Plant Pathology Abstracts and Proceedings.

Interpretive Summary: none required

Technical Abstract: Species in Aspergillus section Flavi commonly infect agricultural staples such as corn, peanuts, cottonseed, and tree nuts and produce an array of mycotoxins, the most potent of which are aflatoxins, which can be classified into B and G toxin chemotype classes. Experimental matings in the laboratory revealed that sexuality has the potential to generate novel toxin chemotypes via meiosis and crossing over, but the specific adaptive processes that create and maintain aflatoxin diversity in nature are unknown. During adaptation, specific toxin genotypes may be favored and swept to fixation or be subjected to drift and frequency-dependent selection. We found that the frequency of sexual reproduction in populations of these fungi is directly correlated with the magnitude of recombination in the aflatoxin gene cluster. Moreover, clonality maintains distinct aflatoxin chemotypes in populations, whereas sexuality generates novel toxin chemotypes but tends to equalize toxin differences in populations. Results from intra- and inter-specific matings indicate that genetic exchange within the aflatoxin gene cluster can occur via crossing over between divergent chemotype lineages. Furthermore, interspecific matings suggest that aflatoxin chemotype evolution can potentially transcend species boundaries. On a contemporary time scale, the frequency of genetic exchange may be driven by differences in fertility among individuals in populations and by local environmental conditions that may directly impact the relative proportion of asexual and sexual reproduction. Our work shows that a combination of population genetic processes may influence aflatoxin chemotype diversity in these agriculturally important fungi.