Genomic Selection for the Traits Expressed after Pollination in Allogamous Plants

Mass selection, a breeding method commonly used to improve allogamous crops, is characterized by low efficiency, especially when a target trait is expressed after pollination. The trait cannot be observed before pollination. Therefore, pollen from unselected plants contributes to the next generation. Genomic selection (GS) enables prediction of the genetic potential of plants from marker genotypes and selection of good pollen parents before pollination. This study investigated the potential of GS in mass selection of a trait expressed after pollination via breeding simulations with annual allogamous plants. We compared GS and phenotypic selection (PS) in traits expressed before and after pollination. Genetic gain attained by PS breeding was much lower than the gain by GS breeding in a trait expressed after pollination. Genetic gain attained by GS breeding was almost equal between traits expressed before pollination and after, except when the breeding cycle was once per year. High efficiency of GS breeding in a trait expressed after pollination was attributable to the high selection accuracy of chromosomes derived from a pollen parent at GS immediately after selection with model update, where we did not select pollen parents because of phenotype requirements. It engendered increased population size and prevented depletion of genetic variation in a breeding population. Results show that GS is effective for improvement of a trait expressed after pollination.