Quantitative trait loci associated with physiological traits for heat tolerance in creeping bentgrass

Abstract

Identification of heat-stress-related quantitative trait loci (QTL) is important for selecting heat-tolerant germplasm. The aim of this study was to identify QTL markers by associating major physiological traits related to heat tolerance to specific regions of the genome in a popula­tion of creeping bentgrass (Agrostis stolonifera L.) with linkage maps and genetic variability for heat tolerance. Phenotypic variation in visual turf quality (TQ) ratings, leaf chlorophyll con­tent (CHL), leaf membrane stability, and canopy temperature depression (CTD) were evaluated under heat-stress conditions in 2-yr field trials (2008 and 2009), greenhouses, and controlled-environmental growth chambers. Phenotypic assessment demonstrated the segregation and variation of heat tolerance in the population and allowed for the association of traits in specific regions of the genome. Quantitative trait loci for every trait were found across the two paren­tal linkage maps, with a total of 32 QTL for all traits. A number of QTL regions were associated with multiple traits, such as on linkage groups 2.2, 4.1, and 4.2 of the L93-10 linkage map and linkage groups 3.1 and 5.1 of the 7418-3 link­age map. Quantitative trait loci identified in this study may be implemented in future studies to identify markers for use in marker-assisted selection to improve heat tolerance or to help elucidate mechanisms regulating heat tolerance in creeping bentgrass.