Increased Sensitivity of Photosynthesis to Anaerobic Conditions Induced by Targeted Inactivation of the Chloroplast ndhB Gene
Increased Sensitivity of Photosynthesis to Anaerobic Conditions Induced by Targeted Inactivation of the Chloroplast ndhB Gene
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叶绿体 ndhB 基因定向失活诱导光合作用对厌氧条件的敏感性增加
DOI：
10.1007/978-94-011-3953-3_459
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
G. Peltier
中科院分区：
文献类型：
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作者：
T. Joët;Z. Cerovic;D. Rumeau;L. Cournac;G. Guedeney;E. Horvàth;P. Medgyesy;G. Peltier
据报道，高等植物的质体基因组含有11个ndh基因，这些基因最近被证明编码NADH脱氢酶（NDH）复合物（1，2）。NDH复合物被认为参与了PSI（3）周围循环电子流或氯呼吸过程中质体醌的还原。ndh基因的失活已通过烟草中的质体转化实现（4）。ndhC、ndhK和ndhJ基因的失活揭示了该复合物是功能性的并且催化PQ池的光照后减少（4）。然而，NDH复合物在光反应过程中的可能参与，特别是参与循环电子流，作者没有显示。先前已经报道，由于NAD（P）/NAD（P）H比率的充分氧化还原平衡（6）以及由于缺少通过Mehler反应排出的电子（7），在厌氧条件下刺激了循环电子流（5）。我们假设，在缺氧条件下，可能会观察到光合活性的差异，在ndh破坏的植物中，循环电子流预计将被刺激。通过质体转化烟草实现了质体indhB基因的靶向失活。同质转化子的分析表明，thatndhB失活导致NDH复合物的消失。虽然在有氧条件下进行的黑暗到光明的过渡过程中，没有观察到控制和失活的ndhB转化体（ndhB-）之间的叶绿素荧光的差异，我们观察到显着减少的电子转移活性在厌氧条件下ndhB-叶。
The plastid genome of higher plants has been reported to contain 11ndhgenes which have been recently shown to encode a NADH dehydrogenase (NDH) complex (1, 2). The NDH complex has been suggested to be involved in the reduction of plastoquinones occurring during cyclic electron flow around PSI (3) or during chlororespiration. Inactivation ofndhgenes has been achieved by plastid transformation in tobacco (4). Inactivation ofndhC,ndhK andndhJ genes revealed that this complex is functional and catalyzes the post-illumination reduction of the PQ pool (4). However, a possible participation of the NDH complex during light reactions and particularly an involvement in cyclic electron flow was not shown by the authors. It has been previously reported that cyclic electron flow was stimulated under anaerobic conditions (5) due to an adequate redox poise of the NAD(P)/NAD(P)H ratio (6) and also to the lack of electrons draining by the Mehler reaction (7). We hypothesized that differences in photosynthetic activity might be observed inndh-disrupted plants in anaerobiosis conditions where cyclic electron flow is expected to be stimulated. Targeted inactivation of the plastidicndhB gene was achieved by plastid transformation of tobacco. Analysis of homoplasmic transformants showed thatndhB inactivation leads to a disappearance of the NDH complex. Although no difference in chlorophyll fluorescence was observed between control and inactivated ndhB transformants (ndhB-) during a dark to light transition performed under aerobic conditions, we observed a significant reduction of electron transfer activity under anaerobic conditions in ndhB-leaves.