Identification of Quantitative Trait Loci Linked to Drought Tolerance in a Colonial x Creeping Bentgrass Hybrid Population

摘要

Identification of quantitative trait loci (QTL) for drought tolerance will allow for detection of important genomic regions associated with specific drought tolerance traits. This study aimed to identify QTL for drought tolerance traits in a colonial bentgrass (Agrostis capillaris L.) x creeping bentgrass (Agrostis stolonifera L.) hybrid backcross population. The traits included relative water content (RWC), turf quality (TQ), electrolyte leakage (EL), chlorophyll content (CHL), normalized difference vegetation index (NDVI), and canopy temperature depression (CTD). A colonial x creeping bentgrass hybrid backcross population segregating for drought tolerance was exposed to drought stress by withholding irrigation in three different locations or environmental conditions (two greenhouse studies in two different years, 2009 and 2010, and a growth chamber study in 2010). Phenotypic trait data were collected in these studies. Significant variation in the parents and the progenies occurred for phenotypic traits and the broad-sense heritability values indicated that the traits were polygenic in nature. A total of 32 potential QTL of varying effects (31 major and 1 minor) were detected on seven chromosomes. Significant overlap of QTL was found, particularly for CHL and CTD on 1A1, CTD, CHL, EL, and NDVI on linkage group 2A1, CTD and TQ on 2A2, TQ and RWC on 5A1 and 5A2, and TQ and CHL on 5A2. The QTL with the strongest effect for each trait (highest likelihood of the odds [LOD] and percent of phenotypic variance explained by the QTL) were CTD (4.19, 18.8%), CHL (4.23, 18.9%), EL (3.25, 14.9%), and NDVI (4.12, 22.4%) on group 2A1, RWC (3.27, 15.7%) on group 5A1, and TQ (4.38, 19.5%) on group 5A2. The analysis of potential genes in the QTL regions for these physiological traits indicate that the QTL may be linked to metabolic factors involved in N metabolism and energy metabolism such as photosynthesis and respiration. The QTL regions identified here could contain important genetic factors conferring drought tolerance in bentgrass species.