Overexpression of NTPCS1 Enhances Zn Tolerance in Tobacco

Phytochelatins (PCs) are well-characterized for their role in detoxifying non-essential metals like cadmium (Cd), but their role in zinc (Zn) homeostasis remains underexplored. In this study, we investigated the role of the <i>Nicotiana tabacum</i> phytochelatin synthase 1 (<i>NtPCS1</i>) in counteracting Zn toxicity in plants. qRT-PCR data showed that the transcript level of the <i>NtPCS1</i> gene was upregulated by ZnSO₄, leading to increased PC production in the wild-type tobacco plants. Functional complementation assays in <i>Arabidopsis thaliana</i> revealed that overexpression of <i>NtPCS1</i> rescued the Zn hypersensitivity of the <i>Atpcs1</i> mutant, with the N-terminal region being indispensable for Zn tolerance. In addition, transgenic tobacco plants overexpressing <i>NtPCS1</i> (PCS1 lines) exhibited superior root elongation under ZnSO₄ stress compared to the wild-type plants, particularly when supplemented with glutathione (GSH). The observed phenotypic advantage is attributed to <i>NtPCS1</i>-mediated overproduction of PCs, which facilitated Zn chelation and enabled cellular detoxification. These findings highlight the important role of NtPCS1 in Zn tolerance via GSH-linked PCs synthesis, offering insights into <i>PCS</i>-mediated Zn detoxification and a genetic strategy for developing Zn-resistant plants.