Adverse effects promoted by inadequate manganese (Mn) supply (deficiency or toxicity) causes inefficiency of the antioxidant system and degradation of chlorophylls. However, 24-epibrassinolide (EBR) is a natural steroid that exhibits beneficial effects on antioxidant metabolism, chlorophyll levels and stress indicators. Therefore, this research aims to evaluate whether EBR application via spray can alleviate oxidative stress in soybean plants exposed to different Mn concentrations and to determine possible contributions of the antioxidant enzymes and photosynthetic pigments. Experiment followed a completely randomized factorial design with two concentrations of 24-epibrassinolide (0 and 100 nM EBR, described as − EBR and + EBR, respectively) and three Mn doses (0.25, 25 and 2500 µM Mn, described as low, control and high supply of Mn, respectively). Plants treated with low and high concentrations of Mn + EBR exhibit significant increases in all enzymes evaluated (superoxide dismutase, catalase, ascorbate peroxidase and peroxidase). To superoxide dismutase (SOD), EBR spray promoted increments of 77%, 38% and 76% under low, control and high Mn supplementation, respectively, compared to same treatment in absence of EBR. Clearly intense activity is linked to SOD contributed by dismutation of superoxide into hydrogen peroxide, being subsequently decomposed by other enzymes (catalase, ascorbate peroxidase and peroxidase). Concomitantly, plants with Mn deficiency and toxicity sprayed with 100 nM EBR presented maintenance of chlorophylls and carotenoids due to reduction of superoxide and hydrogen peroxide and consequently reduced chloroplast membrane damages as indicated by malondialdehyde levels and electrolyte leakage.

中文翻译：

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24-表油菜素内酯对暴露于不同锰供应的大豆植物氧化应激的缓解：抗氧化酶的上调和光合色素的维持

由锰 (Mn) 供应不足（缺乏或毒性）引起的不利影响会导致抗氧化系统效率低下和叶绿素降解。然而，24-表布拉西内酯 (EBR) 是一种天然类固醇，对抗氧化代谢、叶绿素水平和压力指标显示出有益的影响。因此，本研究旨在评估通过喷雾施用 EBR 是否可以减轻暴露于不同锰浓度的大豆植物的氧化应激，并确定抗氧化酶和光合色素的可能贡献。实验遵循完全随机的析因设计，使用两种浓度的 24-表油菜素内酯（0 和 100 nM EBR，分别描述为 - EBR 和 + EBR）和三种 Mn 剂量（0.25、25 和 2500 µM Mn，描述为低、对照和Mn 的高供应量）。用低浓度和高浓度 Mn + EBR 处理的植物表现出所有评估的酶（超氧化物歧化酶、过氧化氢酶、抗坏血酸过氧化物酶和过氧化物酶）的显着增加。对于超氧化物歧化酶 (SOD)，与没有 EBR 的相同处理相比，EBR 喷雾在低、对照和高 Mn 补充下分别促进了 77%、38% 和 76% 的增量。显然，强烈的活性与由超氧化物歧化为过氧化氢、随后被其他酶（过氧化氢酶、抗坏血酸过氧化物酶和过氧化物酶）分解的 SOD 有关。同时，