Title: Identification of QTL mitigating negative impact of semidwarf habit on end-use quality in hard red spring wheat Authors
|Sherman, J -|
|Nash, Deanna -|
|Lanning, S -|
|Martin, J -|
|Blake, N -|
|Talbert, L -|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 27, 2014
Publication Date: N/A
Interpretive Summary: Wheat breeding has influenced bread-making quality in two ways. First, breeders have selected for higher quality through crosses and selection. Second, selection for improved agronomic characteristics, such as grain yield, may lead to changes in end-use quality. In particular, a negative correlation between grain yield and grain protein is common, and thus genes that improve yield may lower protein. Conversely, lines selected for high protein and end-use quality tend to be deficient for grain yield. This interaction is a constant challenge for wheat breeding programs, leading to an interest in genes for improved quality that are independent of grain yield. Genes for semidwarf habit were introduced into hard red spring wheat grown in the Northern Great Plains in the 1960s, and are currently found in most commercial cultivars. The results reported in this study show that the introduction of Rht-D1b into hard red spring wheat breeding germplasm is likely to have had a negative impact on end-use quality traits important in bread-making. The Rht-D1b allele from McNeal caused reduced grain protein and lowered many characteristics associated with dough strength relative to RIL containing the Rht-B1a allele from Thatcher. However, alleles from McNeal at other QTL tended to counteract the negative effect of Rht-D1b. The general negative relationship between end-use quality traits and grain yield is a challenge for developing high end-use quality hard red spring cultivars containing alleles for semidwarf growth habit.
Technical Abstract: The goal of this project was to determine the genetic basis for quality differences between a modern semidwarf spring wheat cultivar ‘McNeal’ and a historically important standard height cultivar ‘Thatcher’. McNeal is higher yielding with lower grain protein than Thatcher, yet has stronger gluten properties important in bread-making. Grain from a total of 160 recombinant inbred lines including 80 semidwarf and 80 standard height lines grown in three environments was tested for bread-making quality. A genetic map of 609 markers was used to identify bread-making quality QTLs including grain protein, flour protein, mixing and baking properties. The McNeal allele for semidwarf habit at Rht-D1 had the largest impact on end-use quality parameters, including grain protein and loaf volume. The primarily negative impact of this allele on quality in McNeal was mitigated by alleles for increased dough strength at other QTL. The allele with the greatest effect on strength was at Gli-B1. Other alleles for increased end-use quality, especially alleles impacting grain protein, tended to be negatively associated with previously identified alleles for grain yield and its components. In sum, this paper shows that the introduction of the Rht alleles for semidwarf habit have presented a challenge to the maintenance of superior end-use quality in modern hard red spring wheat cultivars.