Overexpression of Zinc Finger Transcription Factor ZAT6 Enhances Salt Tolerance

The purpose of the present investigation is to examine the function of the C2H2-type zinc finger transcription factor of Arabidopsis thaliana 6 (ZAT6) in salt stress tolerance in cells of rice (Oryza sativa L.), cotton (Gossypium hirsutum L.) and slash pine (Pinus elliottii Engelm.). Cells of O. sativa, G. hirsutum, and P. elliottii overexpressing ZAT6 were generated using Agrobacterium-mediated genetic transformation. Molecular and functional analysis of transgenic cell lines demonstrate that overexpression of ZAT6 increased tolerance to salt stress by decreasing lipid peroxidation and increasing the content of abscisic acid (ABA) and GA₈, as well as enhancing the activities of antioxidant enzymes such as ascorbate peroxidise (APOX), catalase (CAT), glutathione reductase (GR), and superoxide dismutase (SOD). In rice cells, ZAT6 also increased expression of Ca²⁺-dependent protein kinase genes OsCPK9 and OsCPK25 by 5-7 fold under NaCl stress. Altogether, our results suggest that overexpression of ZAT6 enhanced salt stress tolerance by increasing antioxidant enzyme activity, hormone content and expression of Ca²⁺-dependent protein kinase in transgenic cell lines of different plant species.