The genetics of the domestication syndrome in the perennial intermediate wheatgrass.

摘要

Contemporary agricultural production, particularly of staple grains, relies on the cultivation of annual species. Though highly productive through domestication, modern breeding, and advanced agronomic practices, the cultivation of annual plants often depletes the natural resources of habitat, clean water, soils, and nutrients. Alternatively, the cultivation of perennial species improved through targeted domestication and selection can facilitate regenerative natural systems agriculture, conserving natural resources while producing food. Thinopyrum intermedium, intermediate wheatgrass, was selected for domestication because of its relatively large seeds and high yield. Recently, its future as an economically viable crop has become more plausible with the discovery of a high yielding, non-shattering plant (seed remains attached after maturity) with free-threshing seed (seed that is easily separated from its enclosing hull during harvest). Genetic markers have been developed from three populations of intermediate wheatgrass and utilized for the construction of a consensus genetic map. These resources have been used to identify major quantitative trait loci (QTL) underlying important domestication-related traits, including free-threshing and non-shattering, in two populations and to investigate colinearity with barley. Additionally, the primary wheat domestication gene, Q, has been partially cloned in intermediate wheatgrass and the population genotyped at five tiQ alleles. Three tiQ alleles are associated with free-threshing seed, with one of the three and two additional alleles contributing to non-shattering. QTL analyses revealed three additional loci that contribute to free-threshing and three additional loci that contribute to shattering, as well as several QTL influencing important plant architecture and seed characteristics. These findings, in combination with future phenotyping and genotyping, will allow for the implementation of marker-assisted and genomic selection. This will lead to a faster development of varieties with a suite of important domestication-related traits and increase the efficiency of the intermediate wheatgrass breeding program. (Supplementary files for this dissertation, including scripts for GBS data analyses, are available online).