Heterologous Expression of Haloarchaeal Transporter Genes in Nicotiana Tabacum under Salt and Drought Stresses

Abstract

Climate change and human activities impose severe biotic and abiotic stresses that threaten plant survival. To cope with these extreme conditions, plants have evolved various resistance mechanisms. In recent years, genetic approaches have been increasingly employed to enhance abiotic stress tolerance and develop stress-resistant plants. In this study, we introduced three transporter-related genes from extreme haloarchaea, which thrive in saturated NaCl environments, into the Nicotiana tabacum genome to improve its salt and drought tolerance mechanisms. The U2845, U3508, and CL165 genes were subcloned into the pIPKb004 vector, which includes the cauliflower mosaic virus 35S (CaMV35S) promoter and a hygromycin phosphotransferase II ( hptII ) selection marker, using Gateway cloning. The recombinant vector was introduced into the N. tabacum genome via Agrobacterium-mediated transformation. Wild-type and transgenic plants were cultivated under 150 mM NaCl and 200 mM mannitol, along with a no-stress control. The effects of these genes were evaluated through morphological examination, germination rate analysis, proline and malondialdehyde accumulation measurements, and antioxidant enzyme activity assays. The transgenic lines demonstrated enhanced stress tolerance, as evidenced by improved germination rates, increased proline accumulation, and elevated antioxidant enzyme activities. These findings underscore the potential of haloarchaeal genes as valuable genetic resources for developing stress-tolerant plants.