摘要
以Tiron为自旋探针,检出了越冬针叶叶绿体指示超氧阴离子自由基产生的TH~·ESR信号。此信号可由紫外辐射,也可由光合有效辐射产生。以单位叶绿素量为基数计算的信号强度比已报道的其它植物材料大2～3个数量级。红松叶绿体信号又大于其它针叶树。此信号可被外源SOD,抗坏血酸、乙醇和N_2抑制;随光照增加而增强,12月到次年5月期间又随时间而增强。上述结果表明红松针叶的冬季光氧化伤害与叶绿体中过量超氧阴离子自由基的产生有关。
Tiron semiquinone TH·ESR signal representing O_2^- production was detected from chloroplasts isolated from wintering needles of Korean Pine (Pinus koraiensis), Mongolian. Scotch Pine (Pinus sylvestris var. mongolica) and Korean Spruce (Picea koraiensis). The signal induced by UV or PAR was 2-3 order of magnitude stronger than that reported for other plant materials. It was inhibited by exogenous SOD, vitamin C, ethanol or N_2 and was enhanced by higher irradiance or DCMU. The chloroplasts from Korean Pine seedlings that are most allergic to winter photooxidation gave TH' signals apparently stronger than that of Korean Spruce and Mongolian Scotch Pine sampled during March. This month is critical for the needle injury. In May, when the needles of Korean Pine seedlings had sustained severe injury, their chloroplasts gave TH· signals even stronger than that in March while the signals from chloroplasts of trees of the same species that had recovered from winter declined from March to May. The results support the theory that O_2^- produced by illuminated chloroplasts is related to winter photooxidation injury of Korean Pine seedlings and the injury enhances O_2^- production. A new signal representing another free radical species formed when TH· was inhibited by adding ethanol or vitamin C is also reported.
基金
国家自然科学基金
关键词
超氧阴离子
针叶树
红松
光氧化
superoxide free radical
Korean Pine
photooxidation
