Genetic Components Associated with Cold Tolerance and Turf Quality-Related Traits in St. Augustinegrass.

Although St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is well-adapted for home lawns and commercial landscapes across the southern US, its use in the transition zone is marginal due to insufficient winter hardiness. ‘Raleigh’ is a popular cultivar in this region due to its superior cold tolerance compared to other cultivars, but it possesses several poor aesthetic characteristics such as coarser leaf texture and long inter-node lengths. Therefore, improvement of winter hardiness in combination with superior turf quality remains an important goal for St. Augustinegrass breeders. In the present study, a pseudo-F₂ mapping population of 129 Raleigh x Seville individuals was developed in order to identify quantitative trait loci (QTL) associated with winter hardiness and turf quality-related traits. A total of two hundred simple sequence repeat (SSR) markers were mapped to nine linkage groups. The newly developed linkage map was used to scan for associations with winterkill, spring green-up, turf density, genetic color, leaf texture, and establishment rates. Additionally, freeze tolerance and cold-acclimation ability collected from laboratory-based freeze tests were also evaluated. Putative QTL were identified for each trait using composite interval mapping. Ultimately, identifying associations between phenotypes and DNA markers will improve the speed and efficiency of selecting for winter hardiness and other important quality traits in future breeding lines.