Abstract
Grain protein content (GPC) and yield are of two important traits in wheat, but their negative correlation has hampered their simultaneous improvement in conventional breeding. Wild emmer wheat (Triticum turgidum ssp. dicoccoides) is an important genetic resource for wheat quality improvement. In this study, we report a genome-wide association study (GWAS) using 13116 DArT-seq markers to characterize GPC in 161 wheat lines derived from wild emmer. Using a general linear model, we identified 141 markers that were significantly associated with GPC, and grouped into 48 QTL regions. Using both general linear model and mixed linear model, we identified four significant markers that were grouped into two novel QTL regions on chromosomes 2BS (QGpc.cd1-2B.1) and 7BL (QGpc.cd1-7B.2). The two QTLs have no negative effects on thousand kernel weight (TKW) and should be useful for simultaneous improvement of GPC and TKW in wheat breeding. Searches of public databases revealed 61 putative candidate/flanking genes related to GPC. The putative proteins of interest were grouped in four main categories: enzymes, kinase proteins, metal transport-related proteins, and disease resistance proteins. The linked markers and associated candidate genes provide essential information for cloning genes related to high GPC and performing marker-assisted breeding in wheat.
Highlights
Wheat provides approximately 20% of calories and 25% of proteins in the human diet
Some recombinant inbred lines (RILs) with high grain protein content (GPC) were selected and crossed to each of low/medium-gluten common wheat varieties Mianmai 46 (MM46), Chuanmai 50 (CM50), Kechengmai 2 (KCM2), and Chuanyu 18 (CY18)/YunB 58863 (YB58863) and eight generations of self-fertilization to create a second RILs with 55 individuals (Supplementary Table S1)
The 161 RILs derived from wild emmer were phenotyped in multiple environments and genotyped using the DArT markers to dissect the genetic basis of grain protein accumulation in hexaploid wheat
Summary
Wheat provides approximately 20% of calories and 25% of proteins in the human diet. The nutritional quality of wheat grains has a significant impact on human health and well-being. The grain protein content (GPC) is an important trait for both nutritional value and end-use quality of wheat (Veraverbeke and Delcour, 2002). GWAS for Grain Protein Content wheat grains are inherently low and breeding for improvements in the nutritional quality of wheat, such as increased protein and micronutrient levels in the grain are possible and have the potential to alleviate hunger and nutrient deficiencies. The GPC was negative correlated with grain yield, where phenotypic correlations for these two traits usually range between −0.30 and −0.60 (Klindworth et al, 2009). This characteristic has hampered the simultaneous improvement of these two traits in the conventional wheat breeding. The transfer of alien genes from wheat related species has become an effective approach in the development of new wheat varieties for high GPC or yield
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