Effect of Water Stress on Photochemical Activity of Chloroplast from Wheat

Wheat seedling was osmotic stressed in-0. 2 MPa PEG solution for 24 hours. It was observed that the ratio of chlorophyll emission fluorescence F685/F735 of thylakoid membrane rised; the relative electron transport activity of PS I in chloroplast decreased significantly; and the chlorophyll-protein complex of PS I was degraded remarkably as well. It indicated that there might be a relationship between decreasing of PS I activity and degradation of PS I chlorophyll-protein complex. At the same time, the activities of Ca2+-ATPase and Mg2+-ATPase in chloroplast increased obviously under water stress.