博落回对铅的耐性、富集及生理响应研究

以草本植物博落回（Macleaya cordata）为供试植物，采用沙培盆栽实验研究其对重金属铅（Pb）的耐性、富集及生理响应机制。结果表明：博落回能耐受500 mg/L的Pb胁迫而其生长发育不受影响，高于此浓度时植株生长发育受到抑制。不同组织对Pb的富集能力表现为根>茎>叶，博落回对Pb的富集与转运能力皆随Pb胁迫浓度的升高而减弱。Pb胁迫引起丙二醛（Malondialdehyde, MDA）在植物体内累积。低于500 mg/L的Pb促进叶绿素、可溶性蛋白的合成和抗氧化酶活性的提高，高于此浓度时，则表现为抑制，且导致膜脂过氧化与生物膜的损伤。Pb主要以迁移活性低的化学形态存在于细胞壁和可溶性组分中，浓度升高会导致Pb向迁移毒性强的形态转化。透射电子显微镜（TEM）观察到高浓度的Pb胁迫会损害细胞壁结构，使Pb进入细胞内部，对细胞造成毒害。傅里叶红外光谱仪（FTIR）分析表明，Pb胁迫会提高细胞内-OH、-COOH等基团和有机酸、蛋白质的含量，在低浓度时可与Pb结合，削弱其对博落回的毒性。

Investigation on tolerance, accumulation and physiological responses of Macleaya cordata to lead

The mechanisms of herb Macleaya cordata on the tolerance to lead (Pb) were studied via a sand culture experiment. The results showed that the growth of M. cordata was not affected by 500 mg/L Pb but was inhibited by > 500 mg/L Pb. The Pb accumulation and transportation capacity of M. cordata decreased with the increasing Pb concentrations. The exposure of Pb caused the accumulation of malondialdehyde (MDA) in plants, but < 500 mg/L Pb promoted the synthesis of chlorophyll and soluble protein and the activity of antioxidant enzymes, which were inhibited when the Pb concentration was higher than 500 mg/L, and led to membrane lipid peroxidation and membrane damage. Pb was mainly accumulated in the cell wall and soluble components in the form of low migration speciation. The increase in Pb exposure concentrations resulted in the more transformation of Pb to the chemical forms with a strong migration capacity. Transmission Electron Microscope (TEM) analysis showed that high exposure concentrations of Pb damaged the structure of cell wall, and led to more entrance of Pb into cells, causing toxicity to the cells. Fourier Transform infrared spectroscopy (FTIR) analysis showed that Pb exposure increased the contents of -OH, -COOH, organic acids and proteins in this plant, which might combine with Pb to reduce the toxicity of Pb to M. cordata.