From research findings to educational frameworks: breeding progress and genomic insights into intermediate wheatgrass at the University of Minnesota

Abstract

Intermediate wheatgrass (IWG, Thinopyrum intermedium (Host) Barkworth & D.R. Dewey) is a perennial grain crop that has been under development for inclusion in continuous living cover systems worldwide since the 1980s and specifically at the University of Minnesota (UMN) since 2011. IWG offers multiple ecosystem benefits as a perennial grain crop and has the potential to support rural economies by offering farmers a high-value alternative to the relatively few annual crop options that dominate markets and the landscape. However, improving grain traits, developing markets, and establishing optimal agronomic practices are essential for establishing and ensuring the long-term sustainability of IWG as a grain crop in the Midwest and beyond. This dissertation sheds light on the amount of breeding progress and underlying genomic regions for key IWG traits at UMN and uses this knowledge to make recommendations for future breeding efforts. Thus, 242 parent genets (genetically unique individuals) from UMN IWG breeding cycles 2, 3, 4, and 5 were evaluated in 2 locations (St. Paul and Lamberton, MN) in 2021 and 2022. Genets were genotyped and phenotyped for a variety of domestication and agronomic traits including shattering, brittle rachis, seed size, seed weight, spike characteristics, anthesis timing, and plant height. This dissertation demonstrates that the rate of genetic gain for several traits is significant and improving across breeding cycles; floret and average shattering decreased by ~5% each cycle, and seed area increased by 1% each cycle. Moreover, 33 quantitative trait loci (QTL) for these traits were identified in a Genome-Wide Association Study (GWAS), individually explaining 13% of phenotypic variation, on average. Some QTL appeared to be in close proximity to previously identified domestication – related genes from other studies, and favorable allele frequencies for some QTL appeared to increase across cycles. With these findings, we conclude that the rate of IWG breeding progress could be increased by improved phenotyping methods, incorporation of identified QTL in genomic selection procedures, and decreased time per breeding cycle. In addition to exploring IWG breeding progress at UMN, this dissertation explores the potential to disseminate scientific research into relevant science curriculum. Here, concepts such as the integration of quantitative skills and active learning into curriculum are explored, and a framework for developing and evaluating these curricula is proposed.