Emails: Andrew.sharpe@gifs.ca; lingling.jin@cs.usask.ca

Hybrid Wheatgrass (HWG) is an important, palatable, perennial forage crop cultivated in Saskatchewan and other Western provinces. It results from crosses between quackgrass (QG; Elymus repens, 2n = 6x = 42 SSSSHH) and North American and Eurasian bluebunch wheatgrasses (BBG; Pseudoroegneria spp., 2n = 1x = 14 SS, and 2n = 2x = 28 SSSS). QG is a hardy species with a weedy and invasive nature, but also valuable for wheat improvement programs, capable of crossing with wheat to produce introgression lines with enhanced resistance to Fusarium head blight and stripe rust. Similarly, BBG plays a crucial role in ecosystem stability, soil conservation, and providing forage, but its genetic diversity remains underexplored.

In this study, we conducted a comprehensive analysis of genetic diversity in BBG using single nucleotide polymorphisms (SNPs) across a collection of 145 accessions. First, single nucleotide polymorphisms (SNPs) were mapped using Bowtie, and subsequently identified with GATK, and after filtering, a total of 61,101 (61K) high-quality SNPs were retained for further analysis. SNP density analysis revealed significant variation on chromosomes 2 and 7.

Population structure analysis indicated three major genetic groups, reflecting significant differentiation among populations. Principal component analysis (PCA) highlighted significant axes of variation, with PC1 and PC2 explaining 14.35% and 6.88% of the variation, respectively. Phylogenetic analysis showed well-supported clades, with Pseudoroegneria spicata forming major clades, suggesting high conservation.

Genetic differentiation (FST) and neutrality tests (Tajima's D) indicated substantial genetic divergence between populations. Our results provide new insights into the genetic diversity and structure of BBG, with significant implications for conservation and management efforts.

While this study focuses on the genetic analysis of BBG we are also currently developing reference genomes for HWG, BBG, QG and sequencing selected wheat introgression lines, serving as a valuable resource for advancing wheat pre-breeding programs and contributing to sustainable agriculture.