Laboratory of Plant Stress Responses, Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, 2393 Ikenobe, Miki-cho, Kita-gun, Kagawa, 761-0795, Japan.
Biol Trace Elem Res. 2011 Dec;143(3):1758-76. doi: 10.1007/s12011-011-8998-9. Epub 2011 Feb 24.
In order to observe the possible regulatory role of selenium (Se) in relation to the changes in ascorbate (AsA) glutathione (GSH) levels and to the activities of antioxidant and glyoxalase pathway enzymes, rapeseed (Brassica napus) seedlings were grown in Petri dishes. A set of 10-day-old seedlings was pretreated with 25 μM Se (Sodium selenate) for 48 h. Two levels of drought stress (10% and 20% PEG) were imposed separately as well as on Se-pretreated seedlings, which were grown for another 48 h. Drought stress, at any level, caused a significant increase in GSH and glutathione disulfide (GSSG) content; however, the AsA content increased only under mild stress. The activity of ascorbate peroxidase (APX) was not affected by drought stress. The monodehydroascorbate reductase (MDHAR) and glutathione reductase (GR) activity increased only under mild stress (10% PEG). The activity of dehydroascorbate reductase (DHAR), glutathione S-transferase (GST), glutathione peroxidase (GPX), and glyoxalase I (Gly I) activity significantly increased under any level of drought stress, while catalase (CAT) and glyoxalase II (Gly II) activity decreased. A sharp increase in hydrogen peroxide (H(2)O(2)) and lipid peroxidation (MDA content) was induced by drought stress. On the other hand, Se-pretreated seedlings exposed to drought stress showed a rise in AsA and GSH content, maintained a high GSH/GSSG ratio, and evidenced increased activities of APX, DHAR, MDHAR, GR, GST, GPX, CAT, Gly I, and Gly II as compared with the drought-stressed plants without Se. These seedlings showed a concomitant decrease in GSSG content, H(2)O(2), and the level of lipid peroxidation. The results indicate that the exogenous application of Se increased the tolerance of the plants to drought-induced oxidative damage by enhancing their antioxidant defense and methylglyoxal detoxification systems.
为了观察硒（Se）与抗坏血酸（AsA）-谷胱甘肽（GSH）水平变化和抗氧化及乙二醛酶途径酶活性之间可能存在的调节关系，我们在培养皿中培养了油菜（Brassica napus）幼苗。一组 10 天大的幼苗用 25 μM Se（硒酸钠）预处理 48 h。单独施加了两种水平的干旱胁迫（10%和 20%聚乙二醇）以及施加在 Se 预处理幼苗上的干旱胁迫，处理时间为 48 h。在任何水平的干旱胁迫下，GSH 和谷胱甘肽二硫化物（GSSG）含量均显著增加；然而，仅在轻度胁迫下，AsA 含量增加。干旱胁迫未影响抗坏血酸过氧化物酶（APX）的活性。单脱氢抗坏血酸还原酶（MDHAR）和谷胱甘肽还原酶（GR）的活性仅在轻度胁迫（10%聚乙二醇）下增加。在任何水平的干旱胁迫下，脱氢抗坏血酸还原酶（DHAR）、谷胱甘肽 S-转移酶（GST）、谷胱甘肽过氧化物酶（GPX）和乙二醛酶 I（Gly I）的活性均显著增加，而过氧化物酶（CAT）和乙二醛酶 II（Gly II）的活性降低。干旱胁迫诱导过氧化氢（H₂O₂）和脂质过氧化（MDA 含量）急剧增加。另一方面，暴露于干旱胁迫下的 Se 预处理幼苗中 AsA 和 GSH 含量增加，GSH/GSSG 比值保持较高水平，APX、DHAR、MDHAR、GR、GST、GPX、CAT、Gly I 和 Gly II 的活性均高于未施 Se 的干旱胁迫植物。这些幼苗的 GSSG 含量、H₂O₂和脂质过氧化水平降低。结果表明，外源 Se 的应用通过增强抗氧化防御和甲基乙二醛解毒系统，增加了植物对干旱诱导的氧化损伤的耐受性。
