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Title: MADS-box genes in maize: Frequent targets of selection during domestication

item ZHAO, QIONG - University Of Wisconsin
item WEBER, ALLISON - University Of Wisconsin
item McMullen, Michael
item Guill, Katherine
item DOEBLEY, JOHN - University Of Wisconsin

Submitted to: Genetics Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/13/2010
Publication Date: 12/14/2010
Citation: Zhao, Q., Weber, A., McMullen, M.D., Guill, K.E., Doebley, J. 2010. MADS-box genes in maize: Frequent targets of selection during domestication. Genetics Research. 93:65-75.

Interpretive Summary: The domestication of maize (corn) greatly affected the genetic diversity available for corn improvement by breeding therefore identification of the genes most affected by domestication, i.e. the targets of domestication is important to plant breeders to understand the available diversity. In this manuscript we demonstrate that a particular class of transcription factors, MADS-box genes, was often the target of domestication and therefore have reduced genetic diversity in modern varieties of corn. These results imply that this class of genes have been critical in the evolution of maize as a crop and the study and modification of these genes by geneticists and plant breeders would be expected to affect the properties and productivity of maize.

Technical Abstract: MADS-box genes encode transcription factors that are key regulators of plant inflorescence and flower development. We examined DNA sequence variation in 32 maize MADS-box genes and 32 random loci from the maize genome and investigated their involvement in maize domestication and improvement. Using neutrality tests and a test based on coalescent simulation of a bottleneck model we identified eight genes as putative targets of the artificial selection associated with domestication. According to neutrality tests, one additional gene appears to have been under selection during modern agricultural improvement of maize. For random loci, two genes were indicated as targets of selection during domestication and four additional genes were indicated to be candidate selected loci for maize improvement. This suggests that MADS-box genes were more frequent targets of selection during domestication than genes chosen at random from the genome. Using association mapping in the wild ancestor of maize, teosinte, we were also able to identify several interesting associations between genetic variation in the domestication-candidate MADS-box genes and variation in traits hypothesized to have been under selection during domestication.