Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2006
Publication Date: 8/10/2006
Citation: Carbone, I., Jakobek, J.L., Ramirez-Prado, J.H., Horn, B.W. 2006. The roles of recombination and selection in the evolution of the aflatoxin gene cluster. Phytopathology. Interpretive Summary: Not required for abstract only.
Technical Abstract: The aflatoxin pathway is one of the most intensely studied and well characterized of the polyketide pathways. Here we show for the first time the power in merging macro- and micro-scale analyses in the examination of evolutionary processes acting on the aflatoxin gene cluster in Aspergillus. Macro-scale comparative analyses revealed strong conservation of gene order and copy number among Aspergillus species for modules with two or more pathway genes. The existence of shared ancestral polymorphisms and common haplotypes among closely related species is evidence of trans-species evolution and balancing selection acting on the ancestor of extant Aspergillus species. Population genetic analyses in A. parasiticus indicate both ongoing recombination over the past one million years and positive selection acting to maintain specific terminal pathway chemotypes. These data implicate chemotype-specific strains as driving recombination in populations of A. parasiticus and possibly maintaining aflatoxigenicity. The association of recombination blocks with aflatoxin regulation also indicates an adaptive role of blocks in gene regulation.