Recent advances in the genetics underlying wheat grain protein content and grain protein deviation in hexaploid wheat

Wheat is one of the most important global crops and selection for better performance has been ongoing since ancient times. As a quantitative trait controlled by the interplay of several genomic loci and under the strong influence of the environment, grain protein content (GPC) is of major interest in breeding programs. Here, we review the most recent contributions to the genetics underlying wheat GPC and grain protein deviation (GPD, representing the relationship between grain protein content and yield), together with the performance of genomic prediction models characterizing these traits. A total of 364 significant loci related to GPC and GPD are positioned on the hexaploid wheat genome, highlighting genomic regions where significant independent QTL overlap, with special focus on two regions located on chromosomes 3A and 5A. Some of the corresponding homoeologous sequences co-locate with significant independent QTL reported on the B and D subgenomes. Overlapping independent QTL from different studies are indicative of genomic regions exhibiting stability across environments and genotypes, with promising candidates for improving grain quality.