Briggs et al. 2007
Tue Feb 03 2009
Linkage Mapping of Domestication Loci in a Large Maize–Teosinte Backcross Resource
An ultimate objective of QTL mapping is cloning genes responsible for quantitative traits. However,
projects seldom go beyond segments ,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 backcross (BC)1 population derived from a cross between maize (Zea
mays ssp. mays) and teosinte (ssp. par viglumis) 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.
An ultimate objective of QTL mapping is cloning genes responsible for quantitative traits. However,
projects seldom go beyond segments ,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 backcross (BC)1 population derived from a cross between maize (Zea
mays ssp. mays) and teosinte (ssp. par viglumis) 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.