水稻叶片中过氧化氢与核酮糖-1,5-二磷酸羧化酶/加氧酶降解的关系

Degradation of Ribulose-1, 5-Bisphosphate Carboxylase/Oxygenase in Rice Leaves Under Oxidative Stress Induced by Methyl Viologen

甲基紫精 (MV)处理水稻植株能快速诱导核酮糖 1,5 二磷酸羧化酶 /加氧酶 (Rubisco ,EC 4.1.1.39)及其它可溶性蛋白的降解。MV浓度越高 ,降解速率越高。MV能诱发叶片内源H2 O2 迅速积累。光合电子传递抑制剂DCMU (15 0 μmol/L)能显著抑制MV(10 0 μmol/L)诱导的Rubisco及其它可溶性蛋白的降解 ;活性氧清除剂抗坏血酸 (5mmol/L)、甘露醇 (10mmol/L)、苯甲酸钠 (10mmol/L)均能不同程度地缓解MV诱导的Rubisco及其它可溶性蛋白的降解 ,其中以抗坏血酸的效果为最佳。以上结果表明 :依赖光合电子传递链的活性氧产生可能主导着MV诱导的Rubis

The degradation mechanism of ribulose 1, 5 bisphosphate carboxylase/oxygenase (Rubisco,EC 4.1.1.39) was investigated in leaves of hybrid rice ( Oryza sativa L.) under oxidative stress induced by methyl viologen (MV). Rubisco and other soluble protein contents decreased rapidly when the plants were treated with different concentrations of MV (50, 100, 150 μmol/L)(Figs.1,2). The decrease rate was positively proportional to MV concentration. Hydrogen peroxide (H 2O 2 ) content increased about 24% within 2 h in leaves treated with MV 100 μmol/L (Fig.3). Degradation of Rubisco and other soluble proteins could be inhibited by DCMU(150 μmol/L), an inhibitor of photosynthetic electron transport acting at the site of Q A (Fig.4). When MV was applied together with any of the free radical scavengers, i.e. ascorbate (5 mmol/L), mannitol (10 mmol/L), and sodium benzoate (10 mmol/L), the degradation was obviously attenuated(Fig.5). Based on the above results, it can be concluded that active oxygen species play a key role in the degradation of Rubisco and other soluble proteins in rice leaves induced by MV.