Submitted to: Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/9/2005
Publication Date: 5/27/2005
Citation: Wright, S., Vroh, I., Schroeder, S., Yamasaki, M., Doebley, J., Mcmullen, M.D., Gaut, B. 2005. The genomic extent of artificial selection in maize. Science. 308(5726):1310-1314. Interpretive Summary: Artificial selection is a major factor involved in crop domestication and improvement. The impact of artificial selection on genetic diversity at a genome-wide level is unknown for any crop species. By examining genetic diversity at 774 genes in current maize inbreds and in accessions of the progenitor to cultivated maize, teosinte, we were able to determine that about 2% of genes show strong evidence of selection. These genes become candidates for providing the bases of improvement of agronomic traits seen between modern maize and the wild teosintes. These results impact models of crop domestication and the candidate genes identified in this study may be exploited by plant breeders for maize improvement. Furthermore, our findings impact the thinking of evolutionary biologists and population geneticists on the genetic process of crop domestication.
Technical Abstract: Artificial selection promotes rapid phenotypic evolution, but the number of loci affected by artificial selection is unknown for any domesticated species. Further, the identification of these loci is crucial for uncovering the genetic mechanisms underlying important agronomic traits. We investigated the history of selection on the maize genome, based on single nucleotide polymorphisms at 774 randomly chosen genes in maize (Zea mays ssp. mays) and its wild progenitor teosinte (Zea mays ssp. parviglumis). Our analysis identified two classes of maize genes: genes that experienced a neutral population bottleneck during domestication and genes that retained the footprint of artificial selection. Our analysis estimates that 2% of genes fit in the selected class. Candidate selected genes, particularly those involved in plant growth, were significantly overrepresented in QTL regions mapped for phenotypic differences between maize and teosinte. We also identified candidate genes unrelated to morphological QTLs, including a number of genes associated with amino acid biosynthesis. Overall, these results suggest that ~ 1200 genes have been targeted by artificial selection during maize domestication and improvement.