The Effect of Low Temperature on Membrane Lipid Composition in the Leaves of Bermudagrass.

There has been significant progress in developing freezing tolerance of cultivars in bermudagrass (Cynodon spp.), however, relatively little is known about the mechanisms of injury and resistance in response to a low temperature. Some chilling-sensitive germplasms are dormant very soon when exposed to chilling stress and have freezing tolerance characteristics. Membrane lipid composition plays an important role in low temperature tolerance in plant by changing its content and the degree of fatty acid unsaturation. Our objectives were to quantitatively profile membrane lipid molecule species in three bermudagrass leaves under a chilling stress, discover inter-relationships between specific lipid compositions and low temperature tolerance, and identify specific membrane lipid molecules as potential biomarkers for a low temperature tolerance in bermudagrass. Grasses included a chilling tolerance ‘Tifway’, a standard ‘Celebration’, and a sensitive to chilling stress ‘OKC1131’ with excellent performance under freezing stress. The experiment was a completely randomized experimental design with five replications. The leaf samples were taken 3 times which included before treatment, chilling stress (8ºC day/2 ºC night with a light intensity of 680 μmol·m^-2·s^-1 over a 10-h photoperiod) for 14 days, and chilling stress for 42 days. When greening up under optimum temperature conditions after the chilling stress, the fourth set of leaf samples will be collected. Total 60 lipid samples will be profiled using an automated electrospray ionization tandem mass spectrometry (ESI-MS/MS) approach. Results will be updated in the presentation.