Photorespiration, an essential component of plant metabolism, was upregulated under abiotic stress conditions, such as high light or drought. One of the signals for such upregulation was the rise in reactive oxygen species (ROS). Photorespiration was expected to mitigate oxidative stress by reducing ROS levels. However, it was unclear if ROS levels would increase when photorespiration was lowered. Our goal was to examine the redox status in leaves when photorespiratory metabolism was restricted under low O₂ (medium flushed with N₂ gas) or by adding aminooxyacetic acid (AOA), a photorespiratory inhibitor. We examined the impact of low O₂ and AOA in leaves of Arabidopsis thaliana under dark, moderate, or high light. Downregulation of typical photorespiratory enzymes, including catalase (CAT), glycolate oxidase (GO), and phosphoglycolate phosphatase (PGLP) under low O₂ or with AOA confirmed the lowering of photorespiratory metabolism. A marked increase in ROS levels (superoxide and H₂O₂) indicated the induction of oxidative stress. Thus, our results demonstrated for the first time that restricted photorespiratory conditions increased the extent of oxidative stress. We propose that photorespiration is essential to sustain normal ROS levels and optimize metabolism in cellular compartments of Arabidopsis leaves.

光呼吸是植物代谢的重要组成部分，在非生物胁迫条件下（例如强光或干旱）上调。这种上调的信号之一是活性氧（ROS）的增加。光呼吸有望通过降低活性氧水平来减轻氧化应激。然而，尚不清楚当光呼吸降低时，ROS 水平是否会增加。我们的目标是检查当光呼吸代谢在低 O ₂ （用 N ₂气体冲洗的介质）或通过添加氨氧乙酸 (AOA)（一种光呼吸抑制剂）时受到限制时，叶子中的氧化还原状态。我们研究了暗光、中光或高光下低 O ₂和 AOA 对拟南芥叶片的影响。在低 O ₂或 AOA 条件下，典型光呼吸酶的下调，包括过氧化氢酶 (CAT)、乙醇酸氧化酶 (GO) 和磷酸乙醇酸磷酸酶 (PGLP)，证实了光呼吸代谢的降低。 ROS 水平（超氧化物和 H ₂ O ₂ ）显着增加表明氧化应激的诱导。因此，我们的结果首次证明，限制光呼吸条件会增加氧化应激的程度。我们认为光呼吸对于维持正常的活性氧水平和优化拟南芥叶细胞区室的新陈代谢至关重要。