The Enhancement of Abiotic Stress Tolerance in Arabidopsis via Heterologous Overexpression of TcDHN1, a Dehydrin Identified in the Recalcitrant Seeds of Taxillus chinensis

<i>Taxillus chinensis</i> (DC.) Danser is an important hemiparasitic medicinal plant whose propagation is severely limited by the desiccation sensitivity of its recalcitrant seeds. Dehydrins (DHNs), which protect plants against dehydration-induced stresses such as salinity, drought, and low temperatures, may play a critical role in protecting recalcitrant seeds. However, the role of DHNs in the seeds of <i>T. chinensis</i> remains unclear. In this study, a differentially expressed gene was identified from the seed transcriptome of <i>T. chinensis</i> and designated <i>TcDHN1.</i> Sequence alignment and phylogenetic analyses revealed that <i>TcDHN1</i> encodes a dehydrin protein. Heterologous overexpression of <i>TcDHN1</i> in <i>Arabidopsis</i> did not affect growth under normal conditions. Under salt, drought, and cold stresses, transgenic lines exhibited higher seed germination rates, longer primary roots, and improved seedling growth compared with wild-type (WT) plants. The transgenic lines showed significantly increased activities of antioxidant enzymes, including superoxide dismutase, catalase, and peroxidase. In addition, ectopic overexpression of <i>TcDHN1</i> in <i>Arabidopsis</i> conferred enhanced tolerance to abiotic stresses compared to WT plants, accompanied by increased expression of the stress-responsive genes Responsive to Desiccation 29A (<i>AtRD29A</i>) and Heat Shock Protein 70-1 (<i>AtHSP70-1</i>). The above results indicate that <i>TcDHN1</i> confers enhanced tolerance to abiotic stresses. This study provides a functional characterization of an abiotic stress-responsive gene from recalcitrant seeds and identifies a potential genetic resource for molecular breeding. This could potentially improve abiotic stress resistance in <i>T. chinensis</i> and related medicinal plants.