Submitted to: Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/14/2007
Publication Date: 11/1/2007
Citation: Briggs, W., Mcmullen, M.D., Gaut, B.S., Doebley, J. 2007. Linkage mapping of domestication loci in a large maize-teosinte backcross resource. Genetics. 177:1915-1928. Interpretive Summary: Identification of the genes involved in the domestication of teosinte into cultivated corn provides both a history of crop domestication and novel candidate genes for crop improvement. This study represents the most detailed QTL analysis to date of the genetic basis of domestication for any crop species. In addition, the genetic resources developed in this study will greatly aid isolation of domestication genes. The isolation of domestication genes that will follow from this study is of importance to evolutionary biologists in understanding the genetic mechanisms controlling artificial selection and for corn breeders by providing novel genes to manipulate in corn improvement programs.
Technical Abstract: An ultimate objective of QTL mapping is cloning genes responsible for quantitative traits. However, projects seldom go beyond segments narrower than 5 cM without subsequent breeding and genotyping lines to identify additional crossovers in a genomic region of interest. We report on a QTL analysis performed as a preliminary step in the development of a resource for map-based cloning of domestication and improvement genes in corn. A large BC1 population derived from a cross between maize (Z. mays ssp. mays) and teosinte (ssp. parviglumis) was grown for the analysis. A total of 1749 progenies were genotyped for 304 markers and measured for 22 morphological traits. The results are in agreement with earlier studies showing a small number of genomic regions having greater impact on the morphological traits distinguishing maize and teosinte. Despite considerable power to detect epistasis, few QTL interactions were identified. To create a permanent resource, seed of BC1 plants was archived and 1000 BC2S6 BC1-derived lines are in development for fine mapping and cloning. The identification of four BC1 progeny with crossovers in a single gene, tb1, indicated that enough derived lines already exist to clone many QTL without the need to generate and identify additional crossovers.