Genetic Determinants of Starch, Protein and Asparagine in Common Wheat

Background: Protein (GPC) and starch (GSC) content in common wheat grains determines suitability for further end-use processing and is important quality factor. The level of free asparagine in grains (GFAC) significantly affects suitability for thermal processing. The aim of this genome-wide association studies (GWAS) was to identify markers associated (MTA) with the levels of GPC, GSC and GFAC in elite winter wheat breeding lines, and to identify candidate genes. Methods: In total, 344 winter wheat lines were phenotyped and genotyped with DArTseq markers. Results: GWAS analyses revealed 14 MTAs for GPC, 40 for GSC and 43 for GFAC. New markers have been identified and explained from 6.3% to 12.2% of phenotypic variation. For GPC, region adjacent to 4990459 marker (QGpc.rut.2D) explained 10.2% of the variation and was stable between two years. The novel gene TraesCS7A03G037500, encoding sucrose synthase involved in starch biosynthesis, was identified in proximity of QGsc.rut.7A.2. The TraesCS1B03G0736700 gene, coding NAD(P)H dehydrogenase subunit H involved in the mitochondrial electron transport chain was found in proximity of QGfac.rut.1B.1. Conclusions: These findings provide valuable insights for elucidating inheritance of GCS, and identified MTAs provide molecular markers for reduction of free asparagine and increase of protein content in wheat grains.