Chloroplasts canmove in any direction to avoid stronglight
Chloroplasts canmove in any direction to avoid stronglight
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叶绿体可以向任何方向移动以避免强光
DOI：
10.1007/s10265-010-0364-z
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
M. Wada
中科院分区：
文献类型：
--
作者：
Tsuboi;H.;M. Wada
叶绿体对不同的光强度有反应而迁移。在弱光下，叶绿体聚集在光照区域，以最大限度地提高光吸收和光合作用速率（积累反应）。相反，叶绿体逃避强光以避免光损伤（回避反应）。参与这些现象的光感受器已经在拟南芥（Arabidopsis thaliana）和铁线蕨（Adiantum capillus-veneris）中被鉴定。叶绿体行为已被详细研究积累反应，但没有回避反应。因此，我们利用暗适应的铁线蕨配子体细胞和部分细胞照射蓝光，详细分析了叶绿体回避反应。叶绿体从照射点逃逸。这两个响应的持续时间和迁移的距离叶绿体的总剂量照射成正比。回避反应过程中的运动速度依赖于注量率，但从细胞周边朝向微束的累积反应速度是恒定的，与注量率无关。当一个叶绿体只是部分地用强微束照射时，它在几分钟内向非照射区域移动。在此回避反应期间，两个额外的微束照射施加到同一叶绿体的不同位点。在这些条件下，叶绿体在几分钟的滞后时间后改变了移动方向，而没有滚动。总的来说，这些发现表明叶绿体可以向任何方向移动，并且从来没有内在的极性。在拟南芥叶绿体中也观察到类似的现象。
Chloroplasts migrate in response to different light intensities. Under weak light, chloroplasts gather at an illuminated area to maximize light absorption and photosynthesis rates (the accumulation response). In contrast, chloroplasts escape from strong light to avoid photodamage (the avoidance response). Photoreceptors involved in these phenomena have been identified inArabidopsis thalianaandAdiantum capillus-veneris. Chloroplast behavior has been studied in detail during the accumulation response, but not for the avoidance response. Hence, we analyzed the chloroplast avoidance response in detail using dark-adaptedAdiantumcapillus-venerisgametophyte cells and partial cell irradiation with a microbeam of blue light. Chloroplasts escaped from an irradiated spot. Both duration of this response and the distance of the migrated chloroplasts were proportional to the total fluence irradiated. The speed of movement during the avoidance response was dependent on the fluence rate, but the speed of the accumulation response towards the microbeam from cell periphery was constant irrespective of fluence rate. When a chloroplast was only partially irradiated with a strong microbeam, it moved away towards the non-irradiated region within a few minutes. During this avoidance response two additional microbeam irradiations were applied to different locus of the same chloroplast. Under these conditions the chloroplast changed the moving direction after a lag time of a few minutes without rolling. Taken together, these findings indicate that chloroplasts can move in any direction and never have an intrinsic polarity. Similar phenomenon was observed in chloroplasts ofArabidopsisthalianapalisade cells.