Molecular mechanism of photorespiration by plastidic glutamine synthetase

植物吸收光进行光合作用，但由于光本身对植物可能是危险的，它们需要保护自己免受其破坏性影响。在这里，我们展示了光呼吸可以作为这样一种防御机制。我们构建了富含或减少胞质谷氨酰胺合成酶(GS2)的转基因烟草植株，GS2是光呼吸的关键酶。与对照相比，与对照相比，GS2含量增加一倍的转基因植株的光呼吸能力增强，对高强度光的耐受性增强，而GS2含量减少的转基因植株光呼吸能力减弱，在高强度光下受到更严重的光抑制。我们的结论是，光呼吸保护C3植物免受光抑制。

Plants absorb light for photosynthesis but as light can itself be dangerous to plants, they need to protect themselves against its damaging effects. Here, we show that photorespiration can act as such a defence mechanism. We constructed transgenic tobacco plants enriched or reduced in plastidic glutamine synthetase (GS2), a key enzyme in photorespiration. Those transgenic plants having twice the normal amount of GS2 had an improved capacity for photorespiration and an increased tolerance to high-intensity light, whereas those with a reduced amount of GS2 gad a diminished capacity for photorespiration and were photoinhibited more severely by hight-intensity light compasred with control plants. We conclude that photorespiration protects C3 plants from photoinhibition.