The Protection Of Gsh To Rice Leaf From Proteins Carbonyl And Regulation Of Photosynthesis During Leaf Growth

Rice is a crop wildly grown in China. In agricultural production, early photosynthetic function decay usually causes the decline of crop yield. It is necessary and possible to improve photosynthesis and increase productivity by lengthening active photosynthesis duration. As one of the important antioxidants GSH can effectively decrease protein oxidative modification and up-regulate photosynthesis.Rice (LiangYou6393) was treated with lOmM GSH to increase cellular GSH level, while lOmM BSO (a nontoxic, highly specific inhibitor of γ-glutamylcys synthesis) and1OMm DEM (covalently binding GSH, thereby lowering the intracellular physiologically active levels) to reduce cellular GSH level at4th day after5th leaf full expansion, respectively. In order to explore the effect of GSH on leaf senescence, some physiological parameters were investigated. The results are as follows:(1)GSH can obviously increase the Pn of rice leaves by15%-26%, as well as increasing the content of cellular GSH and chlorophyll and soluble protein (especially Rubisco) contents;(2)GSH had effect on enhancing Fo, but on effect on Fv/Fm;(3) GSH played a important role in defending against protein carbonyls. Above results suggest that GSH can enhance rice photosynthesis through increasing soluble protein (especially Rubisco) contents and decreasing protein carbonyls.To identify the regulation of GSH at chlorophyll relative steady phase and chlorophyll sharp decline phase respectively, rice (LiangYou6393) was treated with10mM GSH at4th day and19th day after5th leaf full expansion. The results were obtained as follows:(1) A remarkable increasing of Pn of rice leaves and the content of chlorophyll and soluble protein was observed in rice leaf treated at4th day, but not obviously in rice leaf treated at19th day;(2) Fo were increased in both treatment, Fv/Fm were increased in rice leaf treated at4th day, whereas decreasing in rice leaf treated at19th day.(3)The relatively content of Rubisco LSU was increased by62%, when rice was treated at4th day. But GSH had a little effect on Rubisco LSU content in rice leaf treated at19th day. These results indicate that GSH can only markedly regulate photosynthetic function at chlorophyll relative steady phase.