Evaluation of a high grain protein QTL from Triticum turgidum L. var. dicoccoides in an adapted durum wheat background

Grain protein concentration (GPC) is an important component of durum wheat (Triticum turgidum L, var. durum) quality. The 'Langdon'-Triticum turgidum L. var. dicoccoides chromosome 6B substitution line [LDN(DIC-6B)] contains the high GPC quantitative trait locus "QGpc.ndsu.6Bb," We evaluated the eff ect of this quantitative trait locus on GPC, grain yield, and other agronom ic traits in an adapted durum wheat background, verified its location on ch romosome 6B and determined its relationship to the GPC locus previously ide ntified. A recombinant inbred population consisting of 110 lines segregatin g for high GPC was developed from the LDN(DIC-6B) with two doses of adapted germplasm. This population was evaluated in the field for GPC at two locat ions in 1995, and for GPC, grain yield, and other agronomic characteristics at three locations in 1996, Segregation analysis for GPC shelved a bimodal distribution, indicating a single genetic factor or a tightly linked gene cluster controlling high GPC, This high GPC locus was insensitive to enviro nmental conditions, Grain protein concentration was not correlated with pla nt height, but was loosely correlated with grain yield and heading date. Qu antitative trait locus analysis using simple regression and interval mappin g procedures identified a locus flanked by Xcdo365 and Xmwg79 on chromosome 6B as having a major effect on GPC. This high GPC locus, which explained u p to 72% of the phenotypic variance, accounted for a 15 g kg(-1) increase i n average GPC, Selection for the two markers flanking the GPC QTL would be highly effective in introgressing this QTL into durum wheat breeding progra ms.