Characterization and Validation of Molecular Markers Linked to Heat and Drought Tolerance for Marker Assisted Selection of Stress-Tolerant Creeping Bentgrass.

Creeping bentgrass (Agrostis stolonifera L.) is a cool-season turfgrass valued for its dense, fine canopy and ability to withstand low mowing heights. Unfortunately, creeping bentgrass has low to moderate stress tolerance which can limit its performance and use during periods of abiotic stress. Two major abiotic stresses affecting creeping bentgrasses are drought and heat which lead to reductions in growth, premature leaf senescence and eventual plant death. The development of elite cultivars with improved stress tolerances would allow plants to maintain greater turf quality during stress periods with fewer inputs. One way to develop improved cultivars is through the use of marker assisted selection which utilizes molecular markers linked to important traits resulting in improved selection speed and efficiency. Potential molecular markers have been identified using QTL (quantitative trait loci) analysis or through the development of candidate gene markers which correspond to genes previously implicated to play important roles in stress tolerance. Using these previously identified markers, a diverse population of creeping bentgrass germplasm consisting of 127 individuals was screened during 2014 and 2015 at both the University of Georgia and at Rutgers University for important physiological traits associated with drought and heat tolerance. These traits include leaf membrane stability, chlorophyll content, NDVI, as well as turf quality. In addition to identifying individuals with improved levels of stress tolerance, association analysis was performed to determine if the previously identified molecular markers were associated with important physiological traits for drought or heat tolerance in this new population. Markers significantly associated with important physiological traits for stress tolerance may be linked with important mechanisms for abiotic stress tolerance and be used in marker assisted selection to develop improved cultivars. The confirmation of these markers will not only support their utility for use in marker assisted selection but may also be useful for identifying key mechanisms for abiotic stress tolerance.