The flexible plant mitochondrial electron transport chain with cytochrome c oxidase (COX) and alternative oxidase (AOX) pathways is known to be modulated by abiotic stress conditions. The effect of salinity stress on the mitochondrial electron transport chain and the importance of COX and AOX pathways for optimization of photosynthesis under salinity stress conditions is not clearly understood. In the current study, importance of COX and AOX pathways for photosynthetic performance of pea plants (Pisum sativum L. Pea Arkel cv) was analysed by using the mitochondrial electron transport chain inhibitors Antimycin A (AA) and salicylhydroxamic acid (SHAM) which restrict the electron flow through COX and AOX pathways respectively. Salinity stress resulted in decreased CO₂ assimilation rates, leaf stomatal conductance, transpiration and leaf intercellular CO₂ concentration in a stress dependent manner. Superimposition of leaves of salt stressed plants with AA and SHAM caused cellular H₂O₂ and O₂⁻ accumulation along with cell death. Additionally, aggravation in decrease of CO₂ assimilation rates, leaf stomatal conductance, transpiration and leaf intercellular CO₂ concentration upon superimposition with AA and SHAM during salinity stress suggests the importance of mitochondrial oxidative electron transport for photosynthesis. Increased expression of AOX1a and AOX2 transcripts along with AOX protein levels indicated up regulation of AOX pathway in leaves during salinity stress. Chlorophyll fluorescence measurements revealed enhanced damage to Photosystem (PS) II in the presence of AA and SHAM during salinity stress. Results suggested the beneficial role of COX and AOX pathways for optimal photosynthetic performance in pea leaves during salinity stress conditions.

已知具有细胞色素c氧化酶（COX）和替代氧化酶（AOX）途径的灵活植物线粒体电子传递链受到非生物胁迫条件的调节。盐度胁迫对线粒体电子传递链的影响以及 COX 和 AOX 途径在盐度胁迫条件下优化光合作用的重要性尚不清楚。在当前的研究中，通过使用限制线粒体电子传递链抑制剂抗霉素A（AA）和水杨基异羟肟酸（SHAM）来分析COX和AOX途径对豌豆植物（ Pisum sativum L. Pea Arkel cv）光合性能的重要性。电子分别流经COX和AOX途径。盐度胁迫导致CO ₂同化率、叶片气孔导度、蒸腾作用和叶片细胞间CO ₂浓度以胁迫依赖性方式降低。盐胁迫植物的叶子与AA和SHAM的叠加导致细胞H ₂ O ₂和O ₂ ^-积累以及细胞死亡。此外，盐胁迫期间叠加AA和SHAM后CO ₂同化率、叶片气孔导度、蒸腾作用和叶片细胞间CO ₂浓度的下降加剧，表明线粒体氧化电子传递对于光合作用的重要性。 AOX1a和AOX2转录物的表达增加以及 AOX 蛋白水平表明盐胁迫期间叶片中 AOX 途径的调节上调。 叶绿素荧光测量表明，在盐度胁迫期间，在 AA 和 SHAM 存在的情况下，光系统 (PS) II 的损伤增强。结果表明，COX 和 AOX 途径在盐胁迫条件下对豌豆叶片的最佳光合作用性能具有有益作用。