Research on chilling-induced damage as a kind of photoinhibition

绿色植物进行光合作用。它为我们提供了大部分的生活能源和大部分的原材料。地球上所有的生物体，植物、动物和细菌，都依赖于阳光中的能量。由于光合作用的重要性，光合作用的研究由来已久，目前几乎所有参与光合作用电子传递链的结构蛋白都已被鉴定并测序。虽然我们有很好的光合装置的静态图像，我们不知道很多关于光合作用在不断变化的环境中的动态方面。例如，在叶片暴露于低温后观察到光合活性的降低。低温对光合作用的伤害具有阈值温度的存在、不可逆性和受害后出现明显症状三个特点。虽然20多年来这些特性的原因一直是个谜，但我们发现这些特性可以用光系统I的光抑制来解释。此外，我们还分离到几个突变体，这些突变体在正常生长条件下没有表现出特殊的表型，但在低温处理后表现出特殊的荧光动力学。这些突变体的特性必须是非常有用的，以了解植物的温度响应的分子机制。

Green plants undertake photosynthesis. It provides us with most of our living energy and most of our raw materials. All the living organisms on the earth, plants, animals and bacteria, depend on the energy in the sunlight. Because of its importance, the research in photosynthesis has long history, and almost all the structural proteins involved in the photosynthetic electron transport chain have been identified and their genes sequenced by now. Although we have really good static image of photosynthetic apparatus, we do not know much about the dynamic aspects of photosynthesis in ever changing environments. For example, decrease of the photosynthetic activity is observed after exposure of leaves to chilling temperatures. Chilling-induced damage to photosynthesis has three characteristics : existence of threshold temperature, irreversibility, and development of visible symptoms after worming up. Although the cause of these characteristics was enigma for more than 20 years, we found that these characteristics could be explained by the photoinhibition of Photosystem I. Furthermore, we isolated several mutants that showed no specific phenotype under usual growth condition, but peculiar fluorescence kinetics after chilling treatment. The characterization of these mutants must be very useful to understand the molecular mechanisms underlining the temperature response of plants.