Mapping and validation of PCR-based markers associated with a major QTL for seed dormancy in wheat

Seed dormancy is one of the important factors controlling pre-harvest sprouting (PHS) resistance in wheat. We identified a major quantitative trait locus (QTL) for seed dormancy on the long arm of wheat chromosome 4A (4AL) via simple sequence repeat (SSR)-based genetic mapping using doubled haploid lines from a cross between Japanese PHS resistant variety 'Kitamoe' and the Alpine non-resistant variety Munstertaler (K/M). The QTL explained 43.3% of total phenotypic variation for seed dormancy under greenhouse conditions. SSR markers flanking the QTL were assigned to the chromosome long arm fraction length 0.59-0.66 on the basis of chromosome deletion analysis, suggesting that the gene(s) controlling seed dormancy are probably located within this region. Under greenhouse conditions, the QTL explained 28.5 and 39.0% of total phenotypic variation for seed dormancy in Haruyutaka/Leader (HT/L) and OS21-5/Haruyokoi (O/HK) populations, respectively. However, in field conditions, the effect was relatively low or not significant in both the K/M and HT/L populations. These markers were considered to be widely useful in common with various genetic backgrounds for improvement of seed dormancy through the use of marker-assisted selection. Further detailed research using near isogenic lines will be needed to define how this major QTL interacts with environmental conditions in our area.