Accuracy of genomic selection for growth and wood quality traits in two control-pollinated progeny trials using exome capture as genotyping platform in Norway spruce

A genomic selection (GS) study of growth and wood quality traits is reported based on control-pollinated Norway spruce families established in two Northern Swedish trials at two locations using exome capture as a genotyping platform. Non-additive effects including dominance and first-order epistatic interactions (including additive-by-additive, dominance-by-dominance, and additive-by-dominance) and marker-by-environment interaction (MxE) effects were dissected in genomic and phenotypic selection models. GS models partitioned additive and non-additive genetic variances more precisely than pedigree-based models. In addition, predictive ability (PA) in GS was substantially increased by including dominance and slightly increased by including M´E effects when these effects are significant. For velocity, response to GS (RGS) per year increased 78.9/80.8%, 86.9/82.9%, and 91.3/88.2% compared with response to phenotypic selection (RPS) per year when GS was based on 1) main marker effects (M), 2) M + M´E effects (A), and 3) A + dominance effects (AD) for sites 1 and 2, respectively. This indicates that including MxE and dominance effects not only improves genetic parameter estimates but also when they are significant may improve the genetic gain. For tree height, Pilodyn, and modulus of elasticity (MOE), RGS per year improved up to 68.9%, 91.3%, and 92.6% compared with RPS per year, respectively