The list of primers used in this study.

<div><p>Plants have developed precise defense mechanisms against cadmium (Cd) stress, with vacuolar compartmentalization of Cd<sup>2+</sup> being a crucial process in Cd detoxification. The transport of Cd into vacuoles by these cation / H<sup>+</sup> antiporters is powered by the pH gradient created by proton pumps. In this study, the full-length cDNA of a vacuolar H<sup>+</sup>-pyrophosphatase (V-PPase) gene from <i>Boehmeria nivea</i> (ramie), <i>BnVP1</i>, was isolated using the rapid amplification of cDNA ends (RACE) method. The open reading frame (ORF) of <i>BnVP1</i> is 2292 bp, encoding a 763 amino acid V-PPase protein with 15 predicted transmembrane domains. Sequence alignment and phylogenetic analysis revealed that <i>BnVP1</i> belongs to the Type I V-PPase family. Quantitative RT-PCR assays demonstrated that <i>BnVP1</i> expression was significantly higher in ramie roots than in shoots. Cd treatments markedly induced <i>BnVP1</i> expression in both roots and leaves of ramie seedlings, with a more pronounced effect in roots. Additionally, <i>BnVP1</i> expression was significantly upregulated by the plant hormone methyl jasmonate (MeJA). Heterologous expression of <i>BnVP1</i> in transgenic <i>Arabidopsis</i> significantly enhanced V-PPase activity in the roots. The growth performance, root elongation, and total chlorophyll content of transgenic plants with high tonoplast H<sup>+</sup>-PPase (V-PPase) activity were superior to those of wild-type plants. Overexpression of <i>BnVP1</i> reduced membrane lipid peroxidation and ion leakage, and significantly increased Cd accumulation in the roots of transgenic <i>Arabidopsis</i> seedlings. This study provides new genetic resources for the phytoremediation of Cd-contaminated farmland.</p></div>