水稻剑叶衰老期Rubisco活化酶对Rubisco活力和光合速率的调节

为明确Rubisco活化酶在叶片衰老期间是否对Rubisco羧化活性和光合速率起调节作用，本文研究了水稻剑叶衰老过程中叶片光合速率、可溶性蛋白含量、Rubisco初始羧化活力及含量，Rubisco活化酶活力及含量。结果表明:净光合速率与Rubisco初始羧化活力和Rubisco活化酶的活力间分别为r2=0.966 3和r2=0.702,Rubisco初始羧化活力与Rubisco活化酶的活力和含量间分别为r2=0.810 3和r2=0.814 3, Rubisco活化酶含量与Rubisco和可溶性蛋白间分别为r2=0.925 7和0.867 5, Rubisco活化酶的活力与含量间r2=0.758 7。Rubisco活化酶的含量占Rubisco含量的0.5%～1.0%,占叶片可溶性总蛋白质的0.5%～0.6%,随着剑叶衰老Rubisco活化酶所占的比值加速下降。这表明水稻剑叶衰老期间，Rubisco活化酶对维持Rubisco初始羧化活力和净光合速率有重要调节作用。

Regulation of Rubisco Carboxylation Activity and Photosynthetic Rate by Rubisco Activase during Leaf Senescence in Rice

Photosynthetic rate , contents of soluble protein, chlorophyll, Rubisco and Rubisco activase, activities of Rubisco initial carboxylation and Rubisco activase were traced to clarify whether Rubisco activase regulates Rubisco activity and photosynthetic rate during flag leaf senescence. There were highly positive correlation between Rubisco activase activity and Rubisco initial carboxylation activity (r2=0.810 3), and between Rubisco activase activity and photosynthetic rate (r2=0.702), between Rubisco activase content and Rubisco activase activity (r2=0.814 3) as well as between Rubisco initial carboxylation activity and photosynthetic rate (r2=0.966 3). The ratio of Rubisco activase to Rubisco content (0.5%-1.0%) or soluble protein content (0.5%-0.6%) was higher in young leaf than in old leaf. It can be suggested that Rubisco activase play an important role in controlling Rubisco initial activity and Pn in process of leaf senescence in rice plant.