多金属富集植物李氏禾根系对铜吸收机理的研究

李氏禾（Leersia hexandra Swartz）是一种多金属富集植物，通过研究其根系吸收铜的途径和方式，有助于解释李氏禾对铜的富集现象，为开发李氏禾修复铜污染土壤的植物修复技术提供科学依据。本文在温室水培条件下，利用钙离子通道抑制剂（LaCl3）和钾离子通道抑制剂（TEA），研究了李氏禾根系铜吸收与钙、钾离子通道的关系；同时，在研究 ATP 酶抑制剂、解偶联剂和低温作用对铜吸收影响的基础上，探讨了李氏禾根系铜吸收与能量代谢的关系。结果表明，在1 mmol＆#183;L-1钙离子通道抑制剂的作用下，李氏禾根对铜的吸收明显被抑制了（p＜0.05）。处理48 h后，李氏禾根中铜的浓度较对照下降了39.2%。这说明李氏禾根吸收铜与钙离子通道密切相关。在5 mmol＆#183;L-1钾离子通道抑制剂的作用下，李氏禾根对铜的吸收与对照没用显著差异。这表明，李氏禾根系对铜的吸收可能不是通过钾离子通道进行的。ATP酶抑制剂钒酸钠（Na3VO4）显著地抑制李氏禾根对铜的吸收（p＜0.05）。25μmol·L^-1和50μmol·L^-1 Na3VO4处理48 h后，李氏禾根中铜的浓度较对照分别下降了26.2%和31.0%。由此，推测李氏禾根系对铜的吸收是一个消耗能量的过程。该结果与解偶联剂抑制实验结果相一致。在25μmo·L^-1和50μmol·L^-1解偶联剂2,4-二硝基苯酚（DNP）作用下，李氏禾根系中的铜浓度较对照分别下降了25.8%和42.7%。低温处理对李氏禾根吸收铜的抑制作用较解偶联剂和ATP酶抑制剂更为明显。2℃下暴露48 h，李氏禾根中铜的浓度较对照（25℃）下降了60.1%。这进一步证明了，李氏禾根系对铜的吸收存在消耗能量的主动过程。

Mechanisms of Cu Uptake in a Multi-metal Accumulating Plant Leersia hexandra Swartz

Leersia hexandra Swartz is a multi-metal accumulating plant. The study on the mechanisms of Cu uptake by roots of L. hexandra will help to understand how plants accumulate copper. Additionally, understanding Cu uptake mechanisms in plants is also valuable for phytoremediation of Cu-contaminated soil by L. hexandra. In the present work, a series of greenhouse hydroponic experiments were carried out to study the relationship of Cu2＋uptake with Ca2＋and K＋channels using a calcium ion channel blocker （LaCl3） and a potassium ion channel blocker （TEA）. Effects of ATPase inhibitor, uncoupler, and low temperature on Cu2＋uptake by roots of L. hexandra were also studied, respectively. Based on these experiments, Cu uptake mechanisms in L. hexandra were discussed. The results showed that Ca2＋channel blocker significantly limited the Cu uptake （p〈0.05）. After 48 h treatment with 1 mmol·L^-1 LaCl3, Cu concentration in the roots was decreased by 39.2%as compared to the control group, which indicated that Cu uptake by roots of L. hexandra was closely related to Ca2＋ channel. Conversely, K＋ channel blocker did not inhibit Cu uptake, suggesting that Cu2＋did not pass through potassium ion channels. ATPase inhibitor （Na3VO4） significantly limited the Cu uptake （p〈0.05）. Cu concentrations in the roots exposed to 25 μmol·L^-1 and 50 μmol·L^-1 Na3VO4 for 48 h were decreased by 26.2% and 31.0%, respectively. Therefore, the Cu uptake by the roots of L. hexandra may need energy consumption. This was supported by the observation that Cu uptake was significantly limited by an uncoupler, 2, 4-dinitrophenol （DNP）. Cu concentrations in roots were decreased by 25.8% and 42.7% compared to control after 48 h exposure to 25 μmol·L^-1 and 50 μmol·L^-1 DNP. Effects of low temperature on Cu uptake were more pronounced than those of ATPase inhibitor and uncoupler. Cu concentration in roots was decreased by 60.1% at 2 ℃ for 48 h. The result confirmed that the Cu uptake by roots of L. hexandra was a