Role of the Arabidopsis At2g21490 dehydrin gene in enhancing tolerance to copper and zinc stress in transgenic tobacco plants

We studied the role of the Arabidopsis At2g21490 (DH2) histidine-rich dehydrin gene in plant responses to copper and zinc stress. Transgenic plants overexpressing the DH2 gene were generated via Agrobacterium-mediated transformation. Progeny from both transgenic and non-transgenic (control) plants were cultivated hydroponically and subjected to short-term stress (100 µM CuCl₂ or 200 µM ZnCl₂ for 24 h) before analysis. The differences observed between transgenic and non-transgenic plants in the expression of phytochelatin synthase (NtPCS) and certain metal transporters (NtMTP1A, NtMTP1B, NtHMA_A, and NtHMA_B) suggest that the DH2 gene plays a role in immobilising excess copper, primarily in the roots, thereby mitigating its harmful effects on the aerial parts of the plant. The overexpression of the DH2 gene influenced the levels of both enzymatic (NtAPX, NtSOD, NtCAT) and nonenzymatic antioxidants, particularly by increasing polyphenolic compounds, such as chlorogenic acid by at least 12-fold and rutin by at least 3-fold. The contribution of the DH2 gene to zinc stress tolerance appears to be less significant.