Quantitative Trait Loci Associated with Delayed Heat-Induced Senescence in Creeping Bentgrass.

Creeping bentgrass (Agostis stolonifera) is a widely used and economically important turfgrass species which often experiences declines during summer months. Elevated temperatures result in the premature senescence and eventually death of valuable turf areas.  Therefore at present there is a great need to develop creeping bentgrass cultivars with improved heat tolerance.  Unfortunately heat tolerance, like many other abiotic stress tolerances, is a complicated trait controlled by multiple genes.  The identification of quantitative trait loci (QTL) allows specific regions of an organism’s genome to be linked to traits of interest.  Markers within these regions can then be used during marker assisted selection to improve the trait of interest in future varieties.  This approach has been used successfully in a number of important annual crop species such as corn and soybean.  A number of important physiological changes occur during heat stress as part of premature senescence including the degradation of chlorophyll and the breakdown of cellular membranes, while the maintenance of these components has been correlated with improved stress tolerance. A creeping bentgrass mapping population was subjected to heat stress trials in both environmental controlled growth chambers as well as green house trails.  Heat tolerance was assessed with several physiological parameters including chlorophyll content, photochemical efficiency, membrane thermostablity, and overall visual turf quality.  The phenotypic results were then used to generate QTL for these important stress related traits.  The identification of QTLs and associated markers corresponding with these traits will allow for the future development of bentgrass lines with delayed heat-induced senescence.