Kasahara Masahiro, Kagawa Takatoshi, Oikawa Kazusato, Suetsugu Noriyuki, Miyao Mitsue, Wada Masamitsu
Division of Biological Regulation and Photobiology, National Institute for Basic Biology, Okazaki 444-8585, Japan.
Nature. 2002;420(6917):829-32. doi: 10.1038/nature01213.
When plants are exposed to light levels higher than those required for photosynthesis, reactive oxygen species are generated in the chloroplasts and cause photodamage. This can occur even under natural growth conditions. To mitigate photodamage, plants have developed several protective mechanisms. One is chloroplast avoidance movement, in which chloroplasts move from the cell surface to the side walls of cells under high light conditions, although experimental support is still awaited. Here, using different classes of mutant defective in chloroplast avoidance movement, we show that these mutants are more susceptible to damage in high light than wild-type plants. Damage of the photosynthetic apparatus and subsequent bleaching of leaf colour and necrosis occur faster under high light conditions in the mutants than in wild-type plants. We conclude that chloroplast avoidance movement actually decreases the amount of light absorption by chloroplasts, and might therefore be important to the survival of plants under natural growth conditions.
当植物暴露于高于光合作用所需的光照强度时，叶绿体中会产生活性氧并导致光损伤。即使在自然生长条件下，这种情况也可能发生。为了减轻光损伤，植物已经发展出了几种保护机制。一种是叶绿体回避运动，即在高光条件下，叶绿体从细胞表面移动到细胞侧壁，不过仍有待实验支持。在这里，我们使用在叶绿体回避运动方面存在缺陷的不同类型突变体，表明这些突变体在高光下比野生型植物更容易受到损伤。在高光条件下，突变体中光合装置的损伤以及随后叶片颜色的漂白和坏死比野生型植物发生得更快。我们得出结论，叶绿体回避运动实际上减少了叶绿体吸收的光量，因此可能对植物在自然生长条件下的存活至关重要。
