LaCl_3和PrCl_3对菠菜离体叶绿体光合磷酸化作用的影响

Effect of LaCl_3, PrCl_3 on Photophosphorylation of Spinach Chloroplasts

LaCl3,PrCl3对离体叶绿体的FeCy光还原活性,随La3+,Pr3+浓度递增而增高,动力学曲线明显呈S形;LaCl3,PrCl3处理叶绿体后,能促进循环(+PMS)和非循环(+FeCy或MV)光合磷酸化反应,提高叶绿体的偶联程度,增加ADP/O及PC比值,对叶绿体膜上的Mg2+ ATP酶及偶联因子Ca2+ ATP酶活力有一定激活作用。这表明LaCl3,PrCl3促进光合作用可能与激活偶联因子活性有关。

The experiment of rare earth(RE) in pot and field trials by spraying on leave, seed dressing and seed soaking has fully proved that the RE, as a microfertilizer, promotes obviously the growth and development of plant under similar ecological condition. The efficiency or level of phosphorylation is a decisive factor in influencing the growth and development of plants. In this paper the effects of RE on the photosynthesis mechanism of plants were studied. The results show that the photoreduction activity of chloroplast in excised leave of spinach on K3Fe(CN)6(FeCy) increases as the concentration of La3+ and Pr3+ in creasing, and the kinetic curve shapes 'S' and the Hill coefficients of the curve are respectived 2.8 and 5.0. The results indicate: (1) Both La3+and Pr3+ obviously promote the chloroplast photoreaction; (2)La3+ and Pr3+ may have the same function mechanism and function point; (3)Pr3+influences more strongly photoreaction of chloroplast to (FeCy) than La3+ does.After the chloroplast were further treated by 15 and 25 μmol·L-1 LaCl3, ADP/O rate and photosynthetic control(PC) value increased in different degree in cycle phosphorylation (+PMS) and cycle photosynthetic phosphorylation(+FeCy, +MV) under 50000 lx illumination.Treating chloroplast with suitable concentration of LaCl3 and PrCl3, the activity of Mg2+ATPase and Ca2+ATPase rised apparently and effect of LaCl3 was more distinct than PrCl3. It is suggested that LaCl3 and PrCl3 greatly enhance the photosynthesis of chloroplast and this is probaly related to these RE compounds, activating photosynthetic phosphorylation factor(CF1) and has nothing to do with transferring electron in photosynthesis.