Beijing Key Laboratory of Farmland Soil Pollution Prevention and Remediation, Key Laboratory of Plant-Soil Interactions of the Ministry of Education, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, PR China.
Beijing Municipal Station of Agro-environmental Monitoring, Beijing 100029, PR China.
Ecotoxicol Environ Saf. 2018 Oct 30;162:571-580. doi: 10.1016/j.ecoenv.2018.07.041. Epub 2018 Jul 18.
Pak choi can readily accumulate cadmium (Cd) into its edible parts; this can pose a threat to human health. Although not essential for higher plants, selenium (Se) can be favorable for plant growth and antioxidative defense under heavy metal stress conditions. A pak choi hydroponic experiment was conducted to investigate the effect of two forms of Se on the Cd uptake kinetics and accumulation and oxidative stress. The results showed that selenite and selenate remarkably enhanced Cd uptake kinetics in pak choi. The maximum Cd uptake rate increased by more than 100% after treatment with 5 µM of selenite and selenate, and it further increased after treatment with 20 µM of both Se forms. The effects of Se on Cd content depended on the Se form, exposure time, and Cd dosage. Selenite reduced the Cd content in shoots by 41% after 3 days of treatment with 10 µM Cd, whereas selenate increased this rate by 89%. Both forms of Se decreased Cd content in the shoots by 40% after 7 days of treatment with 10 µM Cd, but they increased the Cd content by approximately 30% after treatment with 50 µM Cd. Se enhanced Cd-induced oxidative stress in pak choi. Malondialdehyde (MDA) generation was promoted by more than 33% by selenite and selenate treatments in combination with 10 µM Cd, and it was further enhanced by 106% and 185% at 50 µM Cd, respectively. Selenite also increased the HO content at both Cd doses, but selenate did not have significant effects on HO production. The effects of Se on antioxidative enzyme activity also depended on the dose of Cd. Selenite and selenate inhibited catalase activity by 11% and 29%, respectively, at 10 µM Cd, and by 13% and 42%, respectively, at 50 µM Cd. Moreover, both forms of Se increased superoxide dismutase activity after treatment with 10 µM Cd but inhibited its activity at 50 µM Cd. Therefore, Se exhibits dual effects on Cd accumulation and oxidative stress in pak choi and might cause further stress when combined with higher doses of Cd.
白菜容易将镉（Cd）积累到可食用部分，这对人类健康构成威胁。尽管硒（Se）对高等植物不是必需的，但在重金属胁迫条件下，它有利于植物的生长和抗氧化防御。进行了白菜水培实验，以研究两种硒形式对 Cd 吸收动力学和积累以及氧化应激的影响。结果表明，亚硒酸盐和硒酸盐显著增强了白菜对 Cd 的吸收动力学。用 5µM 的亚硒酸盐和硒酸盐处理后，Cd 的最大吸收速率增加了 100%以上，用两种硒形式的 20µM 处理后进一步增加。Se 对 Cd 含量的影响取决于 Se 形态、暴露时间和 Cd 剂量。用 10µM Cd 处理 3 天后，亚硒酸盐将 Cd 的含量减少了 41%，而硒酸盐则增加了 89%。两种 Se 形式均将 10µM Cd 处理 7 天后 Cd 的含量减少了 40%，但用 50µM Cd 处理后，Cd 的含量增加了约 30%。Se 增强了 Cd 诱导的白菜氧化应激。亚硒酸盐和硒酸盐处理与 10µM Cd 结合后，丙二醛（MDA）的生成增加了 33%以上，而在 50µM Cd 下，MDA 的生成分别增加了 106%和 185%。亚硒酸盐还增加了两种 Cd 剂量下的 HO 含量，但硒酸盐对 HO 生成没有显著影响。Se 对抗氧化酶活性的影响也取决于 Cd 的剂量。亚硒酸盐和硒酸盐分别在 10µM Cd 下抑制了 11%和 29%的过氧化氢酶活性，在 50µM Cd 下抑制了 13%和 42%的过氧化氢酶活性。此外，两种硒形式在处理 10µM Cd 后均增加了超氧化物歧化酶活性，但在处理 50µM Cd 时抑制了其活性。因此，Se 对白菜 Cd 积累和氧化应激表现出双重影响，当与更高剂量的 Cd 结合时可能会造成进一步的压力。
