Assessing genetic gain in an intermediate wheatgrass improvement program: A retrospective analysis
Publication: Crop Science
Research collaborators at the University of Minnesota conducted an analysis of intermediate wheatgrass, the perennial crop that produces Kernza® grain, to gather insights for breeding programs looking to improve the crop’s yield and other agriculturally significant traits.
Abstract
The perennial crop intermediate wheatgrass [IWG, Thinopyrum intermedium (Host Barkworth & D.R. Dewey] has been under development as a grain crop since 2011 at the University of Minnesota (UMN). Breeding efforts have targeted larger seed size, reduced shattering, and improved threshability, among other traits. Calculating the rate of genetic gain provides insights into breeding progress and informs adjustments in future breeding practices. In this study, materials from multiple breeding cycles of the UMN IWG breeding program were grown in 4 environments to estimate realized genetic gain of domestication and agronomic traits. A set of 242 parents from breeding cycles 2–5 were planted in an augmented experimental design and evaluated over 2 years in 2 locations. Improvement in the mean values for selected traits from cycles 2 to 5 was observed for most traits. Regression analysis used to estimate the rate of genetic gain was significant for both floret and average shattering, spikelet density, seed area and width, and 10-spike seed weight and spike weight. With this information, we make recommendations for future IWG breeding practices. For example, we recommend phenotyping the two types of shattering independently and selecting earlier anthesis genotypes to improve yield component traits. We conclude that progress for several traits may take decades to achieve desired population means, and could be improved with better phenotyping methods, genomic selection applications, and decreased time per breeding cycle. These findings are applicable to other IWG breeding programs and perennial grain domestication programs.
Plain Language Summary
Since 2011, the University of Minnesota has been developing intermediate wheatgrass as a perennial grain crop focusing on traits such as larger seed size, reduced shattering, and improved threshability. This study evaluated genetic progress across multiple breeding cycles by analyzing parent plants from 4 breeding cycles over 2 years and 2 locations. Significant improvements were observed in key traits, including shattering, seed size, and spikelet density. The study found that while progress has been made, achieving desired trait levels may take decades. Recommendations for future breeding efforts include separately phenotyping two types of shattering, selecting for earlier anthesis to improve yield components, and incorporating better phenotyping and genomic selection methods to accelerate progress. These findings not only guide the ongoing breeding program at the University of Minnesota but also offer valuable insights for other perennial grain domestication efforts worldwide.