ABSTRACT
High temperature damage impairs the growth of tall fescue by inhibiting secondary metabolites. Little is known about the regulation pattern of the fatty acids and carbohydrate metabolism at the whole-transcriptome level in tall fescue under high temperature stress. Here, two tall fescue genotypes, heat tolerant PI578718 and heat sensitive PI234881 were subjected to high temperature stress for 36 h. PI 578718 showed higher SPAD chloroplast value, lower EL and leaf injury than PI 234881 during the first 36 h high-temperature stress. Furthermore, by transcriptomic analysis, 121 genes were found to be induced during the second energy production phase in tall fescue exposed to high-temperature conditions, indicating that there may be one energy-sensing system in cool-season turfgrass to adapt high-temperature conditions. PI 578718 showed higher differentially expressed unigenes involved in fatty acids and carbohydrate metabolism compared with PI 234881 for 36 h heat stress. Interestingly, a metabolomic analysis using GC-MS uncovered that the sugars and sugar alcohol accounted for more than 65.06% of the total 41 metabolites content and high-temperature elevated the rate to 82.89-91.16% in PI 578718. High-temperature damage decreased the rate of fatty acid in the total 41 metabolites content and PI 578718 showed lower content than in PI 234881, which might be attributed to the down-regulated genes in fatty acid biosynthesis pathway in tall fescue. The integration of deep transcriptome and metabolome analyses provides systems-wide datasets to facilitate the identification of crucial regulation factors in cool-season turfgrass in response to high-temperature damage.
