| Summary: | Cadmium (Cd)-induced oxidative stress detrimentally affects hyperaccumulator growth, thereby diminishing the efficacy of phytoremediation technology aimed at Cd pollution abatement. In the domain of plant antioxidant mechanisms, the role of glutathione peroxidase (GPX) in conferring Cd tolerance to tobacco (<i>Nicotiana tabacum</i>) remained unclear. Our investigation employed genome-wide analysis to identify 14 <i>NtGPX</i> genes in tobacco, revealing their organization into seven subgroups characterized by analogous conserved domain patterns. Notably, qPCR analysis highlighted <i>NtGPX8a</i> as markedly responsive to Cd<sup>2+</sup> stress. Subsequent exploration through yeast two-hybridization unveiled NtGPX8a’s utilization of thioredoxins AtTrxZ and AtTrxm2 as electron donors, and without interaction with AtTrx5. Introduction of <i>NtGPX8a</i> into <i>Escherichia coli</i> significantly ameliorated Cd-induced adverse effects on bacterial growth. Transgenic tobacco overexpressing <i>NtGPX8a</i> demonstrated significantly augmented activities of GPX, SOD, POD, and CAT under Cd<sup>2+</sup> stress compared to the wild type (WT). Conversely, these transgenic plants exhibited markedly reduced levels of MDA, H<sub>2</sub>O<sub>2</sub>, and proline. Intriguingly, the expression of <i>NtGPX8a</i> in both <i>E. coli</i> and transgenic tobacco led to increased Cd accumulation, confirming its dual role in enhancing Cd tolerance and accumulation. Consequently, <i>NtGPX8a</i> emerges as a promising candidate gene for engineering transgenic hyperaccumulators endowed with robust tolerance for Cd-contaminated phytoremediation.
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