Laboratory of Plant Biochemistry, Department of Biochemistry, University of Maringá, Maringá, PR, 87020-900, Brazil.
Laboratory of Biological Oxidations, Department of Biochemistry, University of Maringá, Maringá, PR, 87020-900, Brazil.
Environ Sci Pollut Res Int. 2021 Dec;28(47):67711-67723. doi: 10.1007/s11356-021-15368-2. Epub 2021 Jul 14.
Cadmium (Cd) inhibits soybean root growth, but its exact mode of action is still not completely understood. We evaluated the effects of Cd on growth, mitochondrial respiration, lipid peroxidation, total phenols, glutathione, and activities of lipoxygenase (LOX), superoxide dismutase (SOD), and catalase (CAT) in soybean roots. In primary roots, Cd stimulated KCN-insensitive respiration and KCN-SHAM-insensitive respiration, indicating the involvement of the alternative oxidase (AOX) pathway, while it decreased KCN-sensitive respiration, suggesting an inhibition of the cytochrome oxidase pathway (COX). In isolated mitochondria, Cd uncoupled the oxidative phosphorylation since it decreased state III respiration (coupled respiration) and ADP/O and respiratory control ratios, while it increased state IV respiration (depletion of exogenously added ADP). The uncoupling effect increased extramitochondrial LOX activity, lipid peroxidation, and oxidized and reduced glutathione, which induced an antioxidant response with enhanced SOD and CAT activities. In brief, our findings reveal that Cd acts as an uncoupler of the mitochondrial oxidative phosphorylation in soybean roots, disturbing cellular respiration and inducing oxidative cellular stress.
镉（Cd）抑制大豆根的生长，但它的确切作用机制仍不完全清楚。我们评估了 Cd 对大豆根生长、线粒体呼吸、脂质过氧化、总酚、谷胱甘肽、脂氧合酶（LOX）、超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性的影响。在主根中，Cd 刺激 KCN 不敏感呼吸和 KCN-SHAM 不敏感呼吸，表明涉及交替氧化酶（AOX）途径，而它降低了 KCN 敏感呼吸，表明细胞色素氧化酶途径（COX）受到抑制。在分离的线粒体中，Cd 解偶联氧化磷酸化，因为它降低了状态 III 呼吸（偶联呼吸）和 ADP/O 以及呼吸控制比，同时增加了状态 IV 呼吸（耗尽外加的 ADP）。解偶联作用增加了细胞外 LOX 活性、脂质过氧化、氧化和还原谷胱甘肽，从而诱导抗氧化反应，增强 SOD 和 CAT 活性。简而言之，我们的发现表明，Cd 作为大豆根线粒体氧化磷酸化的解偶联剂，干扰细胞呼吸并诱导氧化细胞应激。
