The Response of Antioxidant Enzymes in Cellular Organelles in Cucumber (Cucumis sativus L.) Leaves to Methyl Viologen-induced Photo-oxidative Stress
The Response of Antioxidant Enzymes in Cellular Organelles in Cucumber (Cucumis sativus L.) Leaves to Methyl Viologen-induced Photo-oxidative Stress
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DOI：
10.1007/s10725-006-0023-5
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发表时间：
2006-05
影响因子：
4.2
通讯作者：
X. Song;Chun Lan Tiao;K. Shi;W. Mao;J. Ogweno;Y. Zhou;Jingquan Yu
中科院分区：
文献类型：
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作者：
X. Song;Chun Lan Tiao;K. Shi;W. Mao;J. Ogweno;Y. Zhou;Jingquan Yu
为了阐明不同细胞器抗氧化系统对光氧化胁迫的响应，研究了甲基紫精(MV)处理黄瓜叶片叶绿体、线粒体和细胞质中超氧化物歧化酶(SOD)活性和抗坏血酸-谷胱甘肽(AsA-GSH)循环酶活性的变化。MV的光氧化处理显著降低了叶片的净光合速率(Pn)，增加了光系统II的量子效率(PSⅡ)与固定CO2的量子效率(ΦCO_2)之比，提高了Φ的活性，增加了叶绿体、线粒体和细胞质中的AsA-GSH循环酶的活性。然而，这些增加在叶绿体中最为显著。脱氢抗坏血酸(DHA)、还原型谷胱甘肽(GSH)和氧化还原型谷胱甘肽(GSSG)含量也显著增加，但叶绿体和细胞质中抗坏血酸(ASA)含量略有下降，影响不大。但对线粒体内GSSG和胞质中GSH的影响不大。这些细胞器中的抗坏血酸氧化酶(AO)活性与MV处理无关，而线粒体中的L-半乳糖基-1，4-内酯脱氢酶(GLDH)活性受MV处理的轻微抑制。这些结果表明，MV对叶绿体电子传递的干扰通过串扰信号系统影响整个细胞的代谢，AsA-GSH循环在维持AsA水平方面起主要作用。
In order to clarify the response of antioxidant systems in various cellular organelles to photo-oxidative stress, the activities of superoxide dismutase (SOD) and enzymes of the ascorbate–glutathione (AsA-GSH) cycle were investigated in chloroplasts, mitochondria and cytosol of cucumber leaves subjected to methyl viologen (MV) treatment. Photo-oxidation by MV resulted in significant reductions in net photosynthetic rate (Pn) and increases in the ratio of the quantum efficiency of photosystem II (PSII), ΦPSIIto that of the quantum efficiency of CO2fixation (ΦCO2), followed by increased activities of SOD, and a general increase of AsA-GSH cycle enzymes in chloroplasts, mitochondria and cytosol. These increases were however, most significant in chloroplasts. There were also significant increases in dehydroascorbate (DHA), reduced glutathione (GSH), and oxidized glutathione (GSSG) except that the content of ascorbate (AsA) in chloroplasts and cytosol was slightly decreased and little effected, respectively. However, GSSG in mitochondria and GSH in cytosol were little influenced by the MV treatment. The activity of ascorbate oxidase (AO) in these organelles was independent of the MV treatment while the activity ofl-galactono-1,4- lactone dehydrogenase (GLDH) in mitochondria was slightly inhibited by MV treatment. These results indicate that disturbance of electron transport in chloroplasts by MV influenced the metabolism of whole cell by a crosstalk signaling system and that the AsA-GSH cycle played a primary role in sustaining the levels of AsA.