Markers Associated with Starch, Protein and Asparagine Content in Grain of Common Wheat

Background: Grain protein (GPC) and grain starch (GSC) content in common wheat determines suitability for further end-use processing and is an important quality factor. The level of free asparagine in grains (GFAC) significantly affects suitability for thermal processing. The aim of this genome-wide association study (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: This GWAS revealed 14 MTAs for GPC, 40 for GSC and 43 for GFAC. The new markers were identified and explained from 6.3% to 12.2% of phenotypic variation. For GPC, the region adjacent to marker 4990459 (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 the 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 the proximity of QGfac.rut.1B.1. Conclusions: These findings provide valuable insights for elucidating inheritance of GCS, and the identified MTAs provide molecular markers for the reduction of free asparagine and increase of protein content in wheat grains.