Biology Department, Faculty of Science, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
Plant Sci. 2013 Sep;210:177-82. doi: 10.1016/j.plantsci.2013.05.016. Epub 2013 Jun 7.
Chloroplast movement is important for plant survival under high light and for efficient photosynthesis under low light. This review introduces recent knowledge on chloroplast movement and shows how to analyze the responses and the moving mechanisms, potentially inspiring research in this field. Avoidance from the strong light is mediated by blue light receptor phototropin 2 (phot2) plausibly localized on the chloroplast envelop and accumulation at the week light-irradiated area is mediated by phot1 and phot2 localized on the plasma membrane. Chloroplasts move by chloroplast actin (cp-actin) filaments that must be polymerized by Chloroplast Unusual Positioning1 (CHUP1) at the front side of moving chloroplast. To understand the signal transduction pathways and the mechanism of chloroplast movement, that is, from light capture to motive force-generating mechanism, various methods should be employed based on the various aspects. Observation of chloroplast distribution pattern under different light condition by fixed cell sectioning is somewhat an old-fashioned technique but the most basic and important way. However, most importantly, precise chloroplast behavior during and just after the induction of chloroplast movement by partial cell irradiation using an irradiator with either low light or strong light microbeam should be recorded by time lapse photographs under infrared light and analyzed. Recently various factors involved in chloroplast movement, such as cp-actin filaments and CHUP1, could be traced in Arabidopsis transgenic lines with fluorescent protein tags under a confocal laser scanning microscope (CLSM) and/or a total internal reflection fluorescence microscope (TIRFM). These methods are listed and their advantages and disadvantages are evaluated.
叶绿体运动对于植物在高光下的生存和在低光下的高效光合作用都很重要。本综述介绍了叶绿体运动的最新知识，并展示了如何分析响应和运动机制，这可能会激发该领域的研究。避免强光是通过可能定位于叶绿体包膜上的蓝光受体光受体 2（phot2）介导的，而在弱光照射区域的积累是由定位于质膜上的光受体 1（phot1）和光受体 2（phot2）介导的。叶绿体通过叶绿体肌动蛋白（cp-actin）丝运动，这些丝必须由叶绿体异常定位 1（CHUP1）在移动叶绿体的前侧聚合。为了理解叶绿体运动的信号转导途径和机制，即从光捕获到产生动力的机制，应该根据不同的方面采用各种方法。通过固定细胞切片观察不同光照条件下的叶绿体分布模式虽然有些过时，但却是最基本和最重要的方法。然而，最重要的是，应该通过红外光下的延时照片记录和分析使用弱光或强光微光束的辐照器对细胞进行部分辐照后，叶绿体在诱导运动期间和刚刚之后的精确行为。最近，在共聚焦激光扫描显微镜（CLSM）和/或全内反射荧光显微镜（TIRFM）下，通过带有荧光蛋白标签的拟南芥转基因系，可以追踪到涉及叶绿体运动的各种因素，如 cp-actin 丝和 CHUP1。这些方法被列出，并评估了它们的优缺点。
