Bian Jian-Lin, Guo Jun-Mei, Wang Xue-Dong, Yang Jun-Xing, Yang Jun, Chen Tong-Bin, Cao Liu, Cheng Yong-Xia, Ren Zhan-Hong, Wang Jie, Zhou Xiao-Yong
College of Resource Environment and Tourism, Capital Normal University, Beijing 100048, China.
Center for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
Huan Jing Ke Xue. 2020 Feb 8;41(2):970-978. doi: 10.13227/j.hjkx.201906175.
A hydroponic experiment was conducted to explore the differences in growth status and Cd accumulation characteristics of two L. cultivars (QY-1 and SYH) under different concentrations of cadmium (Cd) stress (0, 2, and 5 mg·L). The Cd subcellular compartmentalization and antioxidant enzyme activities were determined to elucidate the intrinsic mechanism of the differences in the Cd accumulation capacity between the two cultivars of L. Furthermore, field trials were conducted to further verify the differences in phytoremediation of the two cultivars. Results show that neither of the cultivars exhibited obvious growth inhibition under Cd stress. Under the 2 mg·L Cd condition, there were no significant differences in shoot Cd concentrations between the two cultivars. Under 5 mg·L Cd condition, however, the Cd concentrations in both shoot and root of SYH were significantly higher than that of QY-1, which increased by 32.05% and 99.57%, respectively. In addition, the bioconcentration factor (BCF) of the root in SYH is significantly higher than that of QY-1. The subcellular Cd distribution in leaves of the two cultivars of L. showed that, with an increase of Cd stress, Cd concentrations of heat stable protein (HSP) and metal-rich granule (MRG) fractions in leaves significantly increased by 143.69% and 118.91% for QY-1, and by 63.34% and 118.91% for SYH. Thus, the segregation of Cd in HSP and MRG, which was reported to be biological detoxified metal fractions (BDM), might play an important role in the detoxification of L. at a subcellular level under Cd stress. Moreover, the distribution of Cd in the cellular debris fraction might be another important factor contributing to the differences in Cd accumulation of the two L. cultivars, which was 4.41 times higher in SYH than in QY-1 under Cd stress. The results of the antioxidant enzyme activities of two L. cultivars showed that, under the 5 mg·L Cd condition, the antioxidant enzyme system may represent an important detoxification mechanism for QY-1 to cope with stress induced by high concentrations of Cd, while SYH is more effective in reducing the toxicity of Cd by separation of Cd into BDM fractions. The results of the field trial confirmed that the Cd concentrations in the above- and underground parts of SYH were 2.34 and 1.43 times higher than in QY-1, respectively. Therefore, SYH possess a higher Cd phytoextraction capacity than QY-1, and might be a good candidate for the remediation of moderate and mildly Cd-contaminated farmland.
进行了一项水培实验，以探究两个龙葵品种（QY - 1和SYH）在不同浓度镉（Cd）胁迫（0、2和5 mg·L）下的生长状况和镉积累特性差异。测定了镉的亚细胞区室化和抗氧化酶活性，以阐明两个龙葵品种镉积累能力差异的内在机制。此外，进行了田间试验以进一步验证两个品种植物修复能力的差异。结果表明，在镉胁迫下两个品种均未表现出明显的生长抑制。在2 mg·L镉条件下，两个品种地上部镉浓度无显著差异。然而，在5 mg·L镉条件下，SYH地上部和根部的镉浓度均显著高于QY - 1，分别增加了32.05%和99.57%。此外，SYH根部的生物富集系数（BCF）显著高于QY - 1。两个龙葵品种叶片中镉的亚细胞分布表明，随着镉胁迫增加，QY - 1叶片中热稳定蛋白（HSP）和富含金属颗粒（MRG）组分的镉浓度显著增加，分别增加了143.69%和118.91%，SYH分别增加了63.34%和118.91%。因此，据报道作为生物解毒金属组分（BDM）的HSP和MRG中镉的区室化可能在镉胁迫下龙葵亚细胞水平的解毒中起重要作用。此外，细胞碎片组分中镉的分布可能是导致两个龙葵品种镉积累差异的另一个重要因素，在镉胁迫下SYH中该组分的镉含量比QY - 1高4.41倍。两个龙葵品种抗氧化酶活性的结果表明，在5 mg·L镉条件下，抗氧化酶系统可能是QY - 1应对高浓度镉诱导胁迫的重要解毒机制，而SYH通过将镉分离到BDM组分中在降低镉毒性方面更有效。田间试验结果证实，SYH地上部和地下部的镉浓度分别比QY - 1高2.34倍和1.43倍。因此，SYH比QY - 1具有更高的镉植物提取能力，可能是中度和轻度镉污染农田修复的良好候选品种。
