杂交酸模叶片线粒体交替氧化酶呼吸途径在光破坏防御中的作用

以杂交酸模(Rumex K-1)为试材,研究了不同光强下线粒体交替氧化酶呼吸途径(AOX途径)对酸模叶片光破坏的防御作用.结果表明:在200 μmol·m-2·s-1弱光下,用水杨基羟肟酸抑制AOX途径后,Rumex K-1叶片的PSⅡ实际光化学效率、光合线性电子传递速率以及光合放氧速率均显著下降,非还原性QB反应中心显著升高,加重了叶片的光抑制,而活性氧清除机制上调,避免了活性氧的过量积累,部分缓解了Rumex K-1叶片的光抑制；在800 μmol·m-2·s-1强光下,AOX途径受抑,导致Rumex K-1叶片发生严重的光抑制,而此时活性氧清除机制的上调不足以缓解活性氧过量的积累.无论在强光还是弱光下,AOX途径在Rumex K-1叶片的光破坏防御过程中都起着重要作用,而且在强光下,AOX途径对叶片的光破坏防御作用是叶绿体内其他光破坏防御途径所不能代替的.

Role of mitochondrial alternative oxidase(AOX) pathway in photoprotection in Rumex K-1 leaves

Taking Rumex K-1 leaves as test materials,this paper studied the role of mitochondrial alternative oxidase(AOX) pathway in photoprotection under different light intensities.Under low light intensity(200 μmol·m-2·s-1),and after treated with salicylhydroxamic acid to inhibit the AOX pathway,the leaf actual photochemical efficiency of PSⅡ,linear electron transport rate of photosynthesis,and photosynthetic O2 evolution rate all decreased significantly while the non-QB reducing reaction center had a significant increase,indicating that under low light,the photoinhibition was aggravated while the scavenging enzymes of reactive oxygen species(ROS) increased,which avoided the over-accumulation of ROS and partially alleviated the photoinhibition of Rumex K-1 leaves.Under high light intensity(800 μmol·m-2·s-1),the inhibition of AOX pathway caused more severe photoinhibition,and the increased activities of ROS scavenging enzymes were insufficient to prevent the over-accumulation of ROS.This study demonstrated that AOX pathway played an important role in the photoprotection in Rumex K-1 leaves under both high and low light intensities,and the role of AOX pathway in photoprotection under high light could be irreplaceable by the other photoprotection pathways in chloroplast.