Use of Recombinant Substitution Lines for Gene Mapping and QTL Analysis of Bread Making Quality in Wheat

Abstract

Three populations of 41 to 74 Homozygous recombinant substitution lines (RSLs) were used for RFLP mapping and quantitative trait analysis of the following parameters: total proteins (%prot), SDS-sedimentation volume (SDSsed), bread mixing time (Bmxt) and loaf volume (Blvol). The RSLs were developed from crosses between disomic substitution lines involving chromosomes lA, 1B, and 1D of the high-quality wheat cv. ‘Cheyenne’ (Cnn) substituted into the genetic background of the poor quality cv. ‘Chinese Spring’ (CS). The QTL analysis indicated regions in the three chromosomes responsible for the differences between CS and the three disomic substitution lines. The major effect detected on chromosome lA of Cnn was high SDSsed, Bmxt and Blvol associated with the H-M-W Glutenin subunit locus Glu-A1. In addition a QTL was identified distally on the long arm of chromosome lA for Bmxt and Blvol. A high %prot QTL was mapped on the long arm of chromosome 1B of CS and a high Bmxt QTL was mapped on the long arm of chromosome 1B of Cnn. Additionally, this chromosome enhanced SDSsed, Bmxt and Blvol, which were associated with the region of the gliadin and L-M-W Glutenin subunit locus Gli-B1/Glu-B3. A second more proximal region on the short arm of chromosome 1B could be involved in loaf volume. QTL analyses for % prot, showed a strong clear QTL mapped in the centromeric region (XTri/Centromere linkage group) of chromosome 1D with an apparent positive effect brought by CS. For Blvol we revealed two QTLs in opposite phase: one in the Xtri/Centromere region with a positive effect of CS allele, one in the Glu-D1 region with a positive effect of Cnn allele. This organization ‘in repulsion’ in the parental lines could explain the small difference between them for Blvol and the significant transgression observed among the RSLs. No clear candidate gene explained the positive effect of the centromeric region of CS on %prot and Blvol. Contrary to the current belief that wheat bread-making quality is determined primarily by variation at the Glu-1 locus, present results showed that the trait is under a complex control and the Glu-1 loci was only a component of the genetic control of the trait.