Grain Protein Content (GPC) and thousand kernel weight (TKW) QTLs Identified using Durum × Wild Emmer Wheat Mapping Populations Tested in a Range of Environments

Wild emmer wheat (Triticum turgidum ssp. dicoccoides, WEW) harbor high grain protein content (GPC) and therefore is regarded as an important source for improvement of cultivated wheat nutritional value. Genetic dissection of thousand kernel weight (TKW) and grain protein content (GPC) was performed using quantitative trait loci (QTL) analysis, based on a high-density genetic map. The genetic map was constructed based on a recombinant inbred line (RIL) population of 208 F₆ RILs, derived from a cross between T. durum var. Svevo and WEW acc. Y12-3. Genotyping of the RILs with a 15K wheat SNP array yielded 4,166 polymorphic SNP markers, of which 1,510 were designated as skeleton markers. A total map length of 2,169 cM was obtained with an average distance of 1.5 cM between SNPs. A total of 12 GPC QTLs and 11 TKW QTLs were identified under five different environments. No significant correlations were identified between GPC and TKW across all environments. Four major GPC QTLs with favorable alleles from WEW were identified on chromosomes 4BS, 5AS, 6BS and 7BL. The 6BS GPC QTL coincided with the physical position of the NAC transcription factor TtNAM-B1, underlying the cloned QTL, Gpc-B1. Comparisons of the physical intervals of the GPC QTLs described here with the results previously reported in other durum×WEW RIL population led to the discovery of e seven novel GPC QTLs. Therefore, our research emphasizes the importance of GPC QTL dissection in diverse WEW accessions as a source of novel alleles for improvement of GPC in cultivated wheat.