Quantitative Trait Loci Associated with Drought Tolerance in Creeping Bentgrass

Abstract

Improvement in the drought tolerance of the cool‐season perennial grass species creeping bentgrass (Agrostis stolonifera L.) has significant value within the turfgrass industry. Understanding genomic regions associated with quantitative trait loci (QTL) such as drought tolerance will allow for advancement of breeding strategies to identify creeping bentgrass germplasm with improved abiotic stress tolerance. A multiyear and multienvironment study was performed to identify QTL in a mapping population of creeping bentgrass segregating for phenotypic traits associated with drought tolerance. Phenotypic data was collected during two growth chamber studies and 2 yr of a field trial. The phenotypic traits that were measured included turf quality (TQ), relative water content (RWC), canopy temperature depression (CTD), osmotic adjustment (OA), electrolyte leakage (EL), chlorophyll content (CHL), water use efficiency (WUE), and the normalized difference vegetative index (NDVI). Quantitative trait loci were identified for all traits on both parental maps except for OA and EL. Quantitative trait loci were found within all linkage groups except for group 2 in both parents. The linkage group areas that had QTL with a significant amount of overlapping for multiple traits and trials included linkage group 5.2, 7.1, and 7.2 on the drought tolerant parent ‘L‐93’ and groups 4.2 and 7.2 on the drought sensitive parent 7418–3. These and other QTL identified in this study have potential to be used in future studies that aim to more closely identify the genes associated with these QTL areas and for further investigation of their potential for use in marker‐assisted selection practices.

Quantitative Trait Loci Associated with Drought Tolerance in Brachypodium distachyon

“…Co-localization of QTLs for physiological traits and/or with agronomic traits have been reported in plants exposed to drought stress, suggesting a link between individual QTLs and multiple traits (Viger et al, 2013; Borrell et al, 2014; Kapanigowda et al, 2014; Merewitz et al, 2014; Khan et al, 2015). Overlapping QTLs for the chlorophyll fluorescence parameters and plant water status traits were identified in sunflower under drought stress (Kiani et al, 2008).…”

Association of SSR and Candidate Gene Markers with Genetic Variations in Summer Heat and Drought Performance for Creeping Bentgrass

“…Overall visual ratings of the 127 selections and cultivars ranged from 2.5 to 6.6 and from 2.0 to 6.8 during the 2014 drought period in Georgia and New Jersey respectively, and ranged from 2.0 to 6.3 and from 1.0 to 4.7 for Georgia and New Jersey, respectively, for the 2015 drought trials (Fig. These SSR markers had previously been identified in QTL regions linked to heat or drought tolerance in a bentgrass mapping population of 100 selections under both field and controlled-environment conditions (Merewitz et al, 2014;Jespersen et al, 2016). The range of values for EL was 13.0 to 37.8% relative damage among the 127 selections and cultivars in Georgia and was 19.6 to 47.3% in New Jersey for the 2014 drought trials.…”

“…Significant associations between stress tolerance traits and SSR markers were also found in this study, with 21 of the 29 SSR markers found to be significantly linked to physiologically traits. These SSR markers had previously been identified in QTL regions linked to heat or drought tolerance in a bentgrass mapping population of 100 selections under both field and controlled-environment conditions (Merewitz et al, 2014;Jespersen et al, 2016). Traits used to screen the population and subsequently mapped to QTLs included EL, NDVI, RWC, and TQ.…”

“…Previous studies in creeping bentgrass using molecular markers have largely been focused on disease resistance (Chakraborty et al, 2014;Honig et al, 2014). Several recent studies have also identified quantitative trait loci (QTLs) associated with heat and drought tolerance in creeping bentgrass (Merewitz et al, 2014;Jespersen et al, 2016). These studies identified genetic regions linked to important traits such as chlorophyll content (CHL), membrane stability, and leaf water content using a map of 445 markers, of which 200 were simple sequence repeat (SSR) markers.…”

“…A total of 70 markers were screened which included 65 SSR markers and five candidate gene markers. Of the 65 SSR markers, 29 were selected as QTL markers previously associated with either drought or heat tolerance in a creeping bentgrass mapping population (Merewitz et al, 2014;Jespersen et al, 2016). These markers were selected from QTL regions linked to important stress tolerance traits found in these aforementioned studies.…”