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Title: Effects of selection for seedling vigor on the genetic variation in Leymus cinereus

item Robins, Joseph
item Bushman, Shaun
item West, Mark

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2017
Publication Date: 2/4/2017
Citation: Robins, J.G., Bushman, B.S., West, M.S. 2017. Effects of selection for seedling vigor on the genetic variation in Leymus cinereus. Rangeland Ecology and Management. doi: 10.1016/j.rama.2017.01.002.

Interpretive Summary: Although basin wildrye is an important grass species on western North American rangelands, it struggles to form adequate stands in revegetation projects. We developed four populations through selection from the cultivar Trailhead basin wildrye. These four populations were selected for increased seedling vigor (2) and randomly selected (2). We then used these four populations to determine the effects of selection for increased seedling vigor on biomass, seed production, and stand establishment. We also used molecular genetic markers to identify regions of the basin wildrye genome affected by the selection process. Overall, we found selection for seedling vigor to be effective. The second selected populations possessed over 30 % higher emergence rate. We also found the selection process had no effect on the genetic variation associated with biomass, seed production, and stand percentage. Additionally, we found the selected populations to possess slightly less genetic diversity than the random populations and identified a set of molecular marker band frequencies that exhibited differing frequencies in the select and random populations.

Technical Abstract: Basin wildrye (Leymus cinereus [Scribn. & Merr. A. Love])is a perennial grass native to western regions of North America. Despite its importance for rangelands, it lacks adequate seedling vigor and is difficult to establish stands. We undertook to increase the seedling vigor of the basin wildrye cultivar 'Trailhead' by using selection for emergence from deep seeding depth. We carried out two cycles of selection in two select populations and included two random populations, in which not selection occurred. We characterized the indirection effect of the selection on biomass, seed production, and stand percentage in these populations under field conditions. We used AFLP markers to identify regions of the genome associated with the selection by identifying allele frequency changes between the base population and the select and random populations. The second cycle select population and the first cycle random population possessed the highest total emergence from deep seeding (60 and 59 %, respectively) compared to the base population (26 %). The field evaluations showed no differences in genetic variation among the base, select, and random populations for biomass, seed production, nor stand percentage. Based on the analysis of the AFLP markers diversity increased slightly among the random populations and decreased slightly among the select populations. In the selected populations, band frequencies increased for aggcac403, actcag185, and aggcac208. The band frequencies of aggctg212 and actctc66 decreased in both random and selected cycles.