Selection and application of four QTLs for grain protein content in modern wheat cultivars

The grain protein content (GPC) is the key parameter for wheat grain nutritional quality. This study conducted a resampling GWAS analysis using 406 wheat accessions across eight environments, and identified four previously reported GPC QTLs. An analysis of 87 landraces and 259 modern cultivars revealed the loss of superior GPC haplotypes, especially in Chinese cultivars. These haplotypes were preferentially adopted in different agroecological zones and had broad effects on wheat yield and agronomic traits. Most GPC QTLs did not significantly reduce yield, suggesting that high GPC can be achieved without a yield penalty. The results of this study provide a reference for future GPC breeding in wheat using the four identified QTLs.