Improve Thinopyrum Intermedium Germplasm Using Recurrent Selection and Genotyping-By-Sequencing Based Genetic Analysis.

Thinopyrum intermedium, commonly known as intermediate wheatgrass, is a perennial crop that produces large biomass and can be used for forage and biofuel. Its environmental benefits are widely recognized, including reduced soil and water erosion, reduced soil nitrate leaching, increased carbon sequestration, and reduced inputs of energy and pesticide. Intermediate wheatgrass also shows great potential to be developed as a grain crop. The goal of our study is to increase grain yield of intermediate wheatgrass through plant breeding and genetics to obtain a commercially viable perennial grain/biomass crop within the next few years. Collaborating with The Land Institute, we finished the fourth cycle of recurrent selection. The average seed size (8.03mg) of the Cycle 4 population was increased by 15.5%, compared with those from Cycle 3. The best genotypes can produce seed size as high as 15g per thousand grain, about 40% of the wheat seed size. To understand the genetic mechanism behind of agronomic traits like seed size, threshability and height, we are performing genetic analysis using genotyping-by-sequencing (GBS) to discover genome-wide SNP markers. Totally, 3,169 GBS markers from a F1 full-sib population were mapped into 21 linkage groups, which corresponded to 21 chromosomes. A total of 1,009 (32%) markers were mapped to a single site on the barley genome with a P-value cutoff of 1×e^-5. Three IWG linkage groups corresponded to one barley chromosome and the linkage groups show high synteny and colinearity with the matched barley chromosomes. Thus, GBS can be utilized in intermediate wheatgrass for de novo genotyping to develop high-density genetic maps and map QTLs. And about 4,000 high quality GBS markers were obtained from a population of 1,200 genotypes for developing a genomic selection model, which might increase genetic gain and accelerate intermediate wheatgrass population improvement.