The Intermediate Wheatgrass Genome: A Resource for Understanding Mechanisms of Perenniality and Accelerating the Development of Perennial Crops

Thinopyrum intermedium (Intermediate wheatgrass - IWG) is a strong perennial species with prolific biomass production, relatively large seeds and high grain yield (>1,000 kg/ha) that has been targeted for domestication and improvement as a dual-use perennial grain and biomass crop. Significant efforts to improve IWG through traditional breeding have focused on traits such as seed size, free threshing seed, and early maturity. While some progress has been made, accelerating the improvement of IWG is likely possible with genomics-assisted breeding. Previously there were limited molecular breeding and genomic tools for IWG due to its large allohexaploid genome (2n = 6x = 42) and 1C genome size of 12.6 Gb. We have generated a draft genome sequence from a haploid line in collaboration with NRGene using the DeNovoMAGIC 2.0 assembly pipeline, which is being anchored using POPSEQ. Analyses of preliminary pseudochromosomes has enabled the sorting of individual chromosomes into corresponding subgenome groups and provided new information on subgenome evolution in Thinopyrum. These resources will provide vital information for ongoing breeding and molecular studies to improve intermediate wheatgrass as a perennial grain species, along with providing a comparative platform for an ongoing cross-tribe transcriptomic experiment examining the genomic landscape of perenniality across the Pooidae. Collectively, this research will shed light on the complex genetic mechanisms underlying the perennial growth habit while directly accelerating the development of perennial biofuel and grain crops.