Heat stress is a major abiotic stress which affects cool-season plants.  Plants exposed to high temperatures often experience decreases quality and performance and stress related injury.  One of the major symptoms of this heat induced damage is premature leaf senescence, the break-down and re-mobilization of cellular components.  Two of the major aspects of premature leaf senescence are the degradation of the photosynthesizing chloroplast and changes and breakdown in membrane structure.  By comparing lines of turfgrass previously shown to have differing levels of tolerance and the changes in their protein profiles and key proteins throughout heat induced senescence by using 2D-electrophoresis we can better identify important heat tolerance mechanisms and their controlling factors.  Two lines of a bentgrass mapping population previously determined to have differing tolerances to heat stress were grown in a growth chamber maintained at 38 degrees Celsius.  Tissue was harvested at Zero, Two and Four weeks of heat stress.  Differences in the protein profile, including soluble and membrane proteins, of the tolerant and sensitive line were compared using 2-D gel electrophoresis and then differential spots were indentified using mass spectrometry.  Cool-season turfgrasses are an important group of plants commonly impacted by heat stress and by understanding key proteins changes during heat induced senescence and changes in chloroplast and membrane function we can gain a better understanding of the mechanisms of premature leaf senescence and heat tolerances to counter act it, as well as the key genes and proteins involved.