Fatty Acid Profile of Forage Bermudagrass Changes Along a Climatic Gradient.

Cynodon dactylon (bermudagrass) is a warm-season perennial grass commonly used as forage in the southern United States. Little is known about the concentration of fatty acids in bermudagrass and how it changes with acclimation to more temperate climates. Our objectives were to analyze the concentrations of saturated and unsaturated fatty acids in bermudagrass genotypes selected for forage yield and nutritive value and to determine how they change when grown at different latitudes. We collected first cuttings from four replications of five genotypes developed for forage (B2000, Coastal, FL44, Jiggs, and Tif-85), grown at two different latitudes (27.4° N and 30.7° N). Plant samples were analyzed for fatty acid methyl esters using gas chromatography following methods described by the American Oil Chemist Society. There was no difference in concentration of total fat (percent of DM; P = 0.11). Saturated fatty acid concentration (percent of total fat) decreased with increasing latitude (P < 0.0001). Concentrations (g/kg DM) of long-chain fatty acids C12:0, C14:0, C16:0, C18:0 and C:20:0, as well as very-long-chain fatty acids, C21:0, C22:0, C23:0 and C24:0 all contributed to the decrease in saturated fatty acids in bermudagrass grown at 30.7° N. Unsaturated fatty acid concentration (percent of total fat) increased in plants grown at 30.7° N as compared to those grown at 27.4° N (P = 0.0020). Only the concentration of polyunsaturated fatty acids C18:3n3 and C20:5n3 increased in plants grown at 30.7° N as compared to those grown at 27.4° N, whereas monounsaturated fatty acids decreased with increasing latitude. Our results suggest that long- and very-long-chain saturated fatty acids, as well as polyunsaturated fatty acids C18:3n3 and C20:5n3 are important factors contributing to thermal acclimation in forage bermudagrass.