Metabolic Profiling for Metabolites Associated with Heat Tolerance in Perennial Grass Species.

Supraoptimal temperatures limit turfgrass growth, particularly for cool-season grasses. Heat stress on a plant leads to the modification of metabolism that could contribute to induced stress tolerance. The objective of this study was to determine the effects of short-term (6 d) and long-tem (18 d) of heat stress on metabolites changes for cool-season (C3) Kentucky bluegrass (cv. ‘Midnight’) and warm-season (C4) bermudagrass (cv. ‘Tifdwarf’). Plants of each species were subjected to two treatments for 18 d: control - plants were maintained at 20/15 ^oC for Kentucky bluegrass and 30/25 ^oC for bermudagrass; heat stress - plants were exposed to 35/30 ^oC for Kentucky bluegrass and 45/40 ^oC for bermudagrass. Heat stress injury was evaluated by turf quality, photochemical efficiency (Fv/Fm) and electrolyte leakage (EL). At short term heat stress, Bermudagrass had significantly higher turf quality and significantly lower EL than Kentucky bluegrass. At long term heat stress, Bermudagrass had significantly higher turf quality, Fv/Fm and significantly lower EL than Kentucky bluegrass. The type and content of polar metabolites in leaf samples were analyzed using GC/MS. Our results indicated that differential responses of C3 and C4 plants to heat stress mainly exhibited in the metabolism of organic acids, amino acids, sugars and sugar alcohols. Most metabolites showed higher accumulation in bermudagrass compared with Kentucky bluegrass under heat stress, especially at 18 d of heat stress.