Genetic characterization of trait architecture in multi-population half-sib families of the perennial crop intermediate wheatgrass

Authors: Bajgain, Prabin; JUNGERS, JACOB - University Of Minnesota; ANDERSON, JAMES - University Of Minnesota

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/17/2025
Publication Date: 7/26/2025
Citation: Bajgain, P., Jungers, J.M., Anderson, J.A. 2025. Genetic characterization of trait architecture in multi-population half-sib families of the perennial crop intermediate wheatgrass. Crop Science. https://doi.org/10.1002/csc2.70126.
DOI: https://doi.org/10.1002/csc2.70126

Interpretive Summary: Intermediate wheatgrass breeding programs mostly assess traits on hundreds of individual plants. Farmers, on the other hand, establish plants in closely arranged rows for large-scale grain production. A breeder's plots are thus not always representative of large commercial fields. In this experiment, we established plots in rows, as a farmer would, and measured plant performance over multiple locations and years to identify plants with stable yield as they aged. We also identified genetic regions controlling important traits such as yield, seed size, and height. Based on our findings, we recommend that row plots be evaluated regularly by breeding programs for selection and genetic improvement. Doing so will benefit growers by making the data more relatable to their farming operations.

Technical Abstract: The cool-season perennial species Thinopyrum intermedium (intermediate wheatgrass, IWG) is a forage grass recognized for its extensive root structure, high biomass, and promising grain yield potential. The University of Minnesota has been domesticating IWG as a food crop since 2011. While most breeding work is carried out in spaced-planted selection nurseries, these do not represent how the plants are grown in fields for commercial grain production. Therefore, this research evaluated half-sib families (HSFs) established in sward plots over multiple locations and years to study trends in grain production as the plant stands aged. A total of 208 HSFs were assessed for plant height, grain yield, and seed size. Principal component analysis using genetic data detected a weak but visible population structure as genotypes clustered into two groups. Across the field environments, i.e. three years and two locations in Minnesota, USA, substantial variation in trait performance was observed. Thirty-two HSFs exhibited stable grain yield across three years and both locations with no decline in grain production, a crucial finding as IWG yield typically declines after the first two years of cultivation. Trait heritability estimates were the lowest for grain yield (0.36) and plant height had the highest (0.51). A scan of the genome for marker-trait associations identified 42 genomic loci associated with the three traits. These findings suggest that HSFs can be a valuable resource in IWG breeding programs to identify maternal genotypes and sib families with stable yield performance, and should be evaluated on a regular basis.