Metallothionein (MT) is a cysteine-rich, low-molecular-weight protein that can bind to cadmium ions and reduce their toxicity to plants. In this study, we cloned the PaMT3-1 gene encoding an unstable protein of 63 amino acids from the cadmium hyperaccumulator Phytolacca americana. The gene was inserted into a plant expression vector and introduced into tobacco plants. The cadmium content of the transgenic plants was measured after treatment with 100 mM CdCl₂ for 7 days. Transgenic and wild-type roots had similar cadmium contents, whereas the cadmium content of transgenic leaves was 66.28–78.70% of the wild type. The transport coefficient of cadmium in transgenic plants was decreased by 23.31–35.52% relative to the wild type. According to various physiological indexes, including malondialdehyde content, relative electrolyte leakage, root activity, and soluble sugar content, the transgenic plants performed better than the wild type. The PaMT3-1 gene can significantly improve plant resistance to cadmium and has potential as an important gene resource in phytoremediation. Our findings could also contribute to an understanding of complex processes and mechanisms involved in phytoremediation.

金属硫蛋白（MT）是富含半胱氨酸的低分子量蛋白质，可以与镉离子结合并降低其对植物的毒性。在这项研究中，我们从镉超富集的美国商陆植物中克隆了编码63个氨基酸的不稳定蛋白的PaMT3-1基因。该基因被插入植物表达载体中并被引入烟草植物中。在用100 mM CdCl ₂处理后测量转基因植物的镉含量7天。转基因和野生型根的镉含量相似，而转基因叶片的镉含量为野生型的66.28-78.70％。相对于野生型，镉在转基因植物中的转运系数降低了23.31–35.52％。根据各种生理指标，包括丙二醛含量，相对电解质渗漏，根系活性和可溶性糖含量，转基因植物的表现要优于野生型。该PaMT3-1基因可以显著提高镉植物抗性，具有作为植物修复的重要基因资源潜力。我们的发现也可能有助于理解植物修复涉及的复杂过程和机制。