Three-Dimensional Seed Size and Shape QTL in Hexaploid Wheat (Triticum aestivum L.) Populations

Seed size and shape are important traits that have been altered during domestication and are monitored in wheat (Triticum aestivum L.) breeding programs because they may impact yield and milling quality. Quantitative trait loci (QTL) for seed morphology were mapped in two doubled-haploid (DH) wheat populations using three seed axes and elliptic Fourier descriptors of shape. In the Synthetic W7984 x Opata M85 (SynOpDH) population, 31 QTL were detected on all chromosomes except 3D, 4D, 5D, 6B, and 7B. Seed shape QTL in SynOpDH were independent of genes Q, Gpc-B1, Ser5B, S1, S2, S3, and markers for rice (Oryza sativa L.) GW2 and GS3. Environmentally stable QTL on 1A and 2D, as well as a pleiotropic QTL on 5A were detected. QTL on chromosome 1A conditioned uniformly widened grains, 2D affected width, and 5A width and thickness. In the Cayuga x Caledonia DH population, 30 QTL affecting kernel morphology were detected on all chromosomes except 3A, 5D, 6A, 6B, 7A, and 7B. The most significant QTL in this population were on 3D affecting seed length and on 1D and 3B affecting uniform widening. Marker-assisted selection of these QTL for complex dimensions of seed shape may assist in breeding cultivars with improved yield or quality.