Development of a Metabolomics-Assisted Selection Tool for Breeding Cool-Season Turfgrass Species.

Traditional screening methods used for identifying germplasm with improved tolerance to abiotic and biotic stresses can be time and labor intensive.  Recently, metabolomics-assisted selection has emerged as a technique for improving speed and precision of phenotyping plants and is centered around the selection of traits based on chemical biomarkers.  Although this technique has been utilized in breeding forage grass species, information is lacking on the use of this tool for breeding cool-season turfgrass species. Therefore, the objective of this research was to develop a metabolomics-assisted screening method that can be used to guide our breeding efforts and facilitate the selection of cool-season grasses with enhanced stress tolerance levels.  Metabolic profiles were developed for perennial ryegrass (Lolium perenne L.) plants varying in both freezing tolerance levels and crown rust susceptibility (caused by Puccinia coronata f.sp. lolii Brown) using reversed phase-ultra performance liquid chromatography (RP-UPLC) coupled to mass spectrometry (MS).   We identified ten potential biomarkers for freezing tolerance in plants acclimated at 2°C for 2 weeks along with 35 potential biomarkers in plants with improved crown rust resistance.   Presence of the metabolites was confirmed in an additional set of perennial ryegrass plants that varied in susceptibility to both freezing temperatures and crown rust.  Of the total 45 metabolites identified, two were associated with both freezing tolerance and rust resistance.  Consequently, these biomarkers can be used in a plant-breeding program to select for perennial ryegrass plants with improved winter hardiness and superior crown rust resistance.