Suetsugu Noriyuki, Wada Masamitsu
Division of Photobiology, National Institute for Basic Biology, Okazaki 444-8585, Japan.
Biol Chem. 2007 Sep;388(9):927-35. doi: 10.1515/BC.2007.118.
Chloroplasts gather in areas irradiated with weak light to maximize photosynthesis (the accumulation response). They move away from areas irradiated with strong light to minimize damage of the photosynthetic apparatus (the avoidance response). The processes underlying these chloroplast movements can be divided into three parts: photoperception, signal transduction, and chloroplast movement. Photoreceptors for chloroplast movement have been identified recently in various plant species. A blue light receptor phototropin (phot) mediates chloroplast photorelocation movement in the seed plant Arabidopsis thaliana, the fern Adiantum capillus-veneris, the moss Physcomitrella patens and possibly the green alga Mougeotia scalaris. A chimeric photoreceptor between phytochrome and phototropin, neochrome (neo), was found in some advanced ferns and in the green alga M. scalaris. While the mechanism of chloroplast movement is not well understood, it is known that actin filaments play an important role in this process. To understand the molecular mechanisms associated with chloroplast movement, several mutants were isolated in A. thaliana (jac1 and chup1) and the corresponding genes were cloned. In this review, recent progress in photoreceptor research into chloroplast movement in various plant species and the possible factors functioning in signal transduction or the regulation of actin filaments identified in A. thaliana is discussed.
叶绿体聚集在弱光照射区域以最大化光合作用（积累反应）。它们从强光照射区域移开以最小化光合机构的损伤（回避反应）。这些叶绿体运动背后的过程可分为三个部分：光感知、信号转导和叶绿体运动。最近在各种植物物种中已鉴定出叶绿体运动的光受体。蓝光受体向光素（phot）介导种子植物拟南芥、蕨类植物铁线蕨、苔藓小立碗藓以及可能还有绿藻丝状鼓藻中的叶绿体光定位运动。在一些高等蕨类植物和绿藻丝状鼓藻中发现了一种植物色素和向光素之间的嵌合光受体，新色素（neo）。虽然叶绿体运动的机制尚未完全了解，但已知肌动蛋白丝在这一过程中起重要作用。为了了解与叶绿体运动相关的分子机制，在拟南芥中分离出了几个突变体（jac1和chup1）并克隆了相应的基因。在这篇综述中，讨论了各种植物物种中叶绿体运动光受体研究的最新进展以及在拟南芥中鉴定出的可能在信号转导或肌动蛋白丝调节中起作用的因素。
