Single nucleotide polymorphism markers linked to QTL for wheat yield traits

Abstract

Continuous improvement in grain yield is one of the major challenges for wheat (Triticum aestivum L.) breeding worldwide. This study characterized quantitative trait loci (QTL) underlying wheat grain yield and its components using a high-density genetic linkage map developed from a recombinant inbred line (RIL) population derived from ‘Ning7840’ × ‘Clark’. The map consisted of 594 single nucleotide polymorphism and 404 simple sequence repeat markers covering a genetic distance of 4225.7 cM. The RIL population was evaluated for grain yield (GY), spike number per m2 (SNPM), kernel number per spike (KNPS), and thousand-kernel weight (TKW) in three Oklahoma locations from 2001 to 2003. A total of 29 additive QTL (eight for GY, two for SNPM, five for KNPS, and 14 for TKW) were mapped on 13 chromosomes. Eight pairs of epistatic QTL were detected for different yield components: four for GY, two for KNPS, and two for TKW. Four additive QTL, including two for GY and two for KNPS, showed additive × environment interactions. QTL that were repeatable in multiple environments were identified for all traits except SNPM. Positive alleles were dispersed between the two parents for all traits, with ‘Clark’ contributing slightly more. Seven pleiotropic loci were co-localized for at least two traits. Interestingly, all co-localized loci overlapped for TKW, and four of them overlapped for GY. Thus, selecting QTL for TKW may simultaneously select for or against yield or other yield components in breeding.