The Effect Of Endophyte On Physiological Characters Of Tall Fescue Under Drought Stress

Research was conducted to determine the soluble carbohydrate and the activities of protective enzyme of endophyte-infected Crossfire II Tall Fescue and endophyte-uninfected Crossfire II Tall Fescue under sustained drought stress in greenhouse. 1. The contents of total soluble carbohydrate in endophyte-infected Crossfire II were significantly higher than that of in endophyte-uninfected Crossfire II when soil relative water content was reduce to 8.993%(P<0.0 1). Among all soluble carbohydrate determined, the change of sucrose content were most obvious, and fructose, glucose were not steady, but the trend of the change illustrated that the remarkable effect of endophyte on the content of fructose and glucose can be showed only under extreme drought stress ( soil relative water content reduce to 6.062%). 2. The activities of the protective enzymes in membrane system of Crossfire II endophyte-infected and endophyte-uninfected were different in drought stress. The activities of CAT in sheath and leaf of endophyte-infected were significantly higher than that of endophyte-uninfected (P<0.05), and the differences of CAT in sheath were more remarkable (P<0.0 1). However, the activities of POD in plants endophyte-infected were lower remarkably than that of in plants endophyte- uninfected (P<0.05). This phenomenon can be explain or supposed from two aspects: First, endophyte induced the activities of CAT to increase under drought stress, and the activities of CAT increased inhibited the activities of POD: Second. endophyte or its metabolite inhibited the activities of POD. But the phenomenon need to be explained from the molecular biology in order to explore the effect of endophyte on enzyme. 3. The morphological characters of drought tolerance of endophyte-infected Crossfire II Tall Fescue were much better than that of endophyte-uninfected Crossfire II. The recovery rate of endophyte-infected plants was above 70% when the treat of drought stress finished, but the recovery rate of plants endophyte- uninfected was lower than 2%.