强光胁迫下银杏叶片的光抑制及其防御机制  

Photoinhibition and Photoprotection Mechanisms in Ginkgo biloba Leaves under Strong Light Stress

作　　者：李新国[1] 孟庆伟[2] 赵世杰[2] 

机构地区：[1]山东省农业科学院高新技术研究中心,济南250100 [2]山东农业大学生命科学学院,泰安271018

出　　处：《林业科学》2004年第3期56-59,共4页Scientia Silvae Sinicae

基　　金：国家重点基础研究发展规划项目 (G19980 10 10 0 );国家自然科学基金 ( 3 0 0 70 45 8);山东省自然科学基金 (Q99D10 )资助项目

摘　　要：为探讨强光对银杏叶片光合特性的影响 ,对银杏叶片进行强光 (12 0 0 μmolphotons·m- 2 s- 1 )胁迫 5h ,通过分析叶绿素a荧光参数和叶黄素循环组分研究了强光胁迫下银杏叶片的光抑制以及相关的光破坏防御机制。强光胁迫过程中 ,银杏叶片的PSⅡ最大光化学效率 (Fv Fm)明显下降 ,胁迫结束时 ,Fv Fm 接近 0 3。而初始荧光(Fo)则在整个胁迫过程中呈上升趋势。PSⅡ实际光化学效率 (ФPSⅡ)和表观光合电子传递速率 (ETR)均大幅度下降 ,而非光化学猝灭 (NPQ)和天线热耗散 (HDR)明显上升 ,叶黄素循环关键组分玉米黄质 (Z)的相对含量则随着强光处理时间的延长而增加 ,由处理前的 3%上升到胁迫结束时的 6 6 %。结果表明 ,强光胁迫过程中 ,银杏叶片发生了严重的光抑制 ,依赖于叶黄素循环的非光化学猝灭和天线热耗散起到了有效耗散过剩光能的作用 ,但是PSⅡ反应中心可逆失活是银杏叶片Fv Fm 下降的主要原因。In order to study the effect of strong light on photosynthetic characteristics of Ginkgo biloba leaves, the photoinhibition and photoprotection mechanisms were investigated by analyzing chlorophyll a fluorescence parameters and pigment composition of the xanthophyll cycle when G. biloba leaves were exposed to strong light (1 200?μmol photons·m -2 s -1). During 5 h strong light stress, maximal photochemical efficiency of PSⅡ (F v/F m) in G. biloba leaves decreased markedly, with the value of 0.3 for F v/F m at the end of stress. On the contrary, initial fluorescence yield (F o) increased obviously during the whole stress. Both non cyclic electron transport efficiency (Ф PSⅡ) and apparent electron transport rate (ETR) decreased markedly under strong light (1 200?μmol photons·m -2s -1). Hot dissipation of antenna (HDR) increased during the stress. The increase of non|photochemical quenching (NPQ) was accompanied by the increase of relative contents of zeaxanthin (Z) during the time course of stress. The results showed that severe photoinhibition occurred in G. biloba leaves, HDR and the xanthophyll cycle dependent NPQ were valid to alleviate strong light damage by dissipating excess energy efficiently in G. biloba leaves. However, reversible inactivation of PSⅡ centers was the main factor causing the decrease of F v/F m.

关 键 词：强光胁迫 银杏 叶片 光抑制 防御机制 叶黄素循环 光合“午休”现象 气孔限制 

分 类 号：S567.19[农业科学—中草药栽培] S792.95[农业科学—作物学]