Study On The Physiological Response And The Regulation Of Phospholipase D In Chorispora Bungeana Under Drought Stress

Chorispora bungeana Fisch. and C.A. Mey?Chorispora bungeana? is a rare alpine subnival perennial herbage plant species that has a strong resistance to external environment. By using PEG-6000 to imitate drought stress, We firstly explored the mechanism of biochemical and physiological responses of Chorispora bungeana including lipid peroxidation, active oxygen and free radical metabolism, and osmotic adjustment substances. T he photosynthetic characteristic of Chorispora bungeana was studied under drought stress with exogenous glycine. Then by adding exogenous PA,Ca²⁺, and n-butyl alcohol to the plantlets of Chorispora bungeana, we studied the relationship of PA ? Ca²⁺ and PLD under drought stress. The main results are as follows:?1? Under drought stress, both the MDA content and the relative electrical conductivity increased compared with the control, indicating the cell membrane was damaged because of membrane lipid peroxidation and active oxygen. The balance of the active oxygen is broken, so it makes active oxygen and free radicals rapidly accumulating in plant. The activities of SOD, POD, CAT and APX peaked before ROS. But, at the end of treatment, O^2-? and H₂O₂ accumulated greatly that may be caused by the low level of antioxidant enzyme synthesis or the high level of antioxidant enzyme decomposition. The changes of free proline content and soluble protein content revealed that they participated the regulation of permeability. The contents of K+, Na+ and Ca²⁺ increased under light and moderate drought stress, but decreased under heavy drought stress.?2? Under drought stress with exogenous glycine, the photosynthetic system of Chorispora bungeana was affected significantly. In this study, drought stress influenced the chlorophyll content, chlorophylla, chlorophyllb, chlorophylla/b,Mg²⁺, Fe³⁺, q N, PS?, NPQ, NO, Fm', and ETR, especially in 20%PEG-6000.The exogenous glycine?10 m M? relieved the damage of PS?. However, the high level of exogenous glycine would restain PS?and synthesis of photosynthetic pigments.?3? Drought stress induced the increase of PLD activity and the intracellular Ca²⁺ content. They showed the same trend. The PLD activity is promoted by exogenous Ca²⁺ When PLD activity was inhibited, the intracellular Ca²⁺ content decreased. There was a correlation between PLD activity and Ca²⁺. PA may participate the drought stress responding pathway of PLD by increasing the intracellular Ca²⁺.