Breeding and Genomic Resources for Intermediate Wheatgrass and Perennial Agriculture

Intermediate wheatgrass (Thinopyrum intermedium) is a cool-season perennial grass used for soil conservation, grazing, and hay production, and has demonstrated potential for the development of perennial grain and biomass crops.  As a tertiary source of disease resistance genes, intermediate wheatgrass (IWG) ranks among closest perennial relatives of wheat (Triticum aestivum). Like wheat, IWG is allohexploid (2n=6x=42) and has a geographic origin, center of diversity, and adaptation range similar to wheat. A survey of 182 IWG accessions reveals two genetically distinct and diverse meta-populations, spanning Europe and Asia, which provide a valuable source of natural germplasm. Moreover, advanced genomic resources will be used to elucidate genetic differences between annual and perennial relatives of wheat and develop perennial grain, forage, and biomass crops. Molecular-genetic maps have been constructed from full-sib IWG populations, using genotype-by-sequencing (GBS) approaches, with a goal of constructing high-density maps for QTL mapping, genome sequence assembly, and genomic selection. Genome and transcriptome reference sequences from a haploid IWG plant (estimated 1C genome size of 12.6 Gb), and related population, will be assembled using a POPSEQ approach with a goal of 90X coverage from short insert paired-end and large insert mate-pair libraries. Field evaluations have been established to identify genes and QTLs controlling functionally-important seed, grain, and biomass production traits in diverse environments and management regimes including non-competitive and competitive grass-legume species mixtures. Comparisons of gene expression profiles from various tissues of annual and perennial forms of wheat, wheatgrass, and Brachypodium aim to elucidate the genetic control of perennial regrowth.