Plant & Animal Genomes XIV Conference

January 14-18, 2006
Town & Country Convention Center
San Diego, CA

A Large Scale Screen For Artificial Selection In Maize Identifies Candidate Agronomic Loci For Domestication And Crop Improvement

Masanori Yamasaki¹ , Stephen I. Wright² , Maud I. Tenaillon³ , Irie Vroh Bi⁴ , Steve G. Schroeder¹ , Hector Sanchez-Villeda¹ , John F. Doebley⁵ , Brandon S. Gaut⁶ , Michael D. McMullen^1,7

¹  Department of Agronomy, Plant Science Unit, University of Missouri, Columbia, Missouri 65211

²  Department of Biology, York University, Toronto, Ontario M3J 1P3, Canada

³  Station de Génétique Végétale UMR C8120, Ferme du Moulon, 91190 Gif sur Yvette, France

⁴  Institute for Genomic Diversity, Cornell University, Ithaca, New York 14853

⁵  Department of Genetics, University of Wisconsin, Madison, Wisconsin 53706

⁶  Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92697

⁷  Plant Genetics Research Unit, Agricultural Research Service, U. S. Department of Agriculture, Columbia, Missouri 65211

Maize (Zea mays ssp. mays) was domesticated from its wild progenitor teosinte (Zea mays ssp. parviglumis) through a single domestication event in southern Mexico between 6,000 and 9,000 years ago. This domestication event resulted in the original maize landrace varieties, which were spread throughout the Americas by Native Americans and adapted to a wide range of environmental conditions. Starting with landraces, 20th century plant breeders selected inbred lines of maize for use in hybrid maize production. Artificial selection during domestication and crop improvement involved selection of specific alleles at genes controlling key morphological and agronomic traits, resulting in reduced genetic diversity relative to unselected genes. We are conducting an investigation of the genetic consequences of artificial selection in maize. Analysis of sequence diversity at 774 genes in teosinte and maize inbred lines indicated that 2 to 4 % of maize genes (~1200 genes) exhibit evidence of artificial selection. In an additional study to efficiently identify selected genes, 1,095 genes were sequenced in maize inbreds, and 35 genes with zero sequence diversity in maize inbreds were chosen as potential targets of selection and sequenced in diverse maize landraces and teosintes. Genes affected by artificial selection during domestication or improvement were identified by population genetics approaches. The selected genes have functions consistent with agronomic selection for plant growth, nutritional quality, maturity, and productivity. Our large scale screen for artificial selection allows identification of genes of potential agronomic importance even when gene function and the phenotype of interest are unknown.