Mapping QTL for End-Use Quality in Soft Winter Wheat.

Soft wheat is used to make a wide variety of products and thus variation for quality parameters is important to breed soft wheat cultivars suitable for different uses.  Breeders need more knowledge about the genetics of soft wheat quality and systems for marker-assisted selection (MAS).  MAS is best for loci and alleles that have positive effects on the trait over multiple genetic backgrounds.  The Wheat CAP project mapped soft wheat quality using seven biparental mapping populations, each with at least 150 RILs, 250 markers, and tested in four environments for eight quality parameters.  The quality traits include solvent retention capacity (SRC) tests for pentosan, starch damage, gluten strength, and water absorption along with flour yield, flour protein, test weight, and softness equivalent.  Forty-two trait-population combinations were mapped.  Multiple QTL were noted, although QTL with large effects were common.  In 20% of the trait/population combinations the maximum R² value exceeded 0.30 and it exceeded 0.15 in 80% of the combinations.  Sixteen chromosome regions had QTL with R² > 0.15 in 1 or more populations.  Of the 16 regions, four appeared to have broad utility for MAS in most populations, five were clearly populations specific, and seven needed more data.  Broad QTL for gluten strength and SRC traits were located on 1B near the centromere and likely reflect the effects of the rye translocation as well as Glu-B1.  A region of 2B near the centromere produced large effects on milling and SRC traits in all six populations.  DArT analysis of an association mapping panel of 182 soft winter wheat cultivars confirmed some of the QTL of the biparental crosses but also supported that quality traits rarely map independent of other traits.  QTL affect most often affect both milling and flour quality.