Evaluation of Genomic Selection in the Context of Initiating a Winter Barley Breeding Program.

To respond quickly to climate, disease, and market changes, plant breeders must implement new selection methods to release improved varieties more quickly. Breeding schemes based on phenotypic selection take five to ten years between the initial cross and the release of an improved variety. Genomic selection (GS), a relatively new method for selection in plants, is faster because lines can be evaluated in earlier generations and at multiple times per year. While spring barley has been produced in Minnesota for over a century, winter barley is envisioned as a new valuable crop that could be part of a double cropping system with soybeans. For two breeding cycles, we have chosen lines predicted by genomic marker data to have the best low temperature tolerance, malt extract, and grain yield. Also, for each cycle, a group of lines was chosen at random as a control, and in the first cycle, a group of lines was chosen by phenotypic selection. The lines have been evaluated in three locations for winter hardiness in terms of survival and vigor and for height and heading date. The objectives of this study were to 1) assess GS for rate of gain from selection and effect on phenotypic variation and 2) determine the change in allele frequencies in each cycle of selection for markers linked to known winter hardiness genes. Improvement in winter survival made steady progress between cycles one and two of GS. Rate of gain was slightly lower for GS than for phenotypic selection, but the ability to conduct multiple cycles of GS per year would make up for this. Phenotypic variation in terms of the range of trait values was consistent across the first two cycles of GS, and the population showed a wider range in phenotypic values after two cycles of GS than after one cycle of phenotypic selection. Markers for several genes known to affect winter hardiness became nearly fixed after the second cycle of GS. This empirical evaluation of the efficiency of GS will inform plant breeders who are considering whether to adopt this new breeding strategy.