Membrane Composition and Membrane Proteins Associated with Heat Tolerance in Hard Fescue.

High temperature is an important abiotic stress leading to deterioration in hard fescue quality during summer months. Heat injury is characterized by leaf senescence and loss of membrane stability and integrity. The objective of this study is to investigate whether different membrane sterol, fatty acids or membrane protein composition is related to the different level of leaf senescence and membrane stability among hard fescue cultivars differing in heat tolerance. Two cultivars of hard fescue differing in heat tolerance were exposed to high temperature at 38/33 °C(day/night temperatures), and the same two cultivars of hard fescue were also exposed to optimal temperature at 22/18 °C as the controls. The degree of heat-induced leaf senescence was assessed by measuring chlorophyll content and photochemical efficiency. Leaf membrane damages were determined by measuring the electrolyte leakage. The result showed that different fatty acid, sterol and membrane protein profile could contribute to the variation of heat tolerance.