Genome-Wide Identification and Functional Characterization of Dof Transcription Factors Involved in Salt Stress...

The DNA binding with one finger (Dof) transcription factor family plays critical roles in plant growth, development, and stress responses; however, their involvement in coordinating stress adaptation with natural rubber biosynthesis remains largely unexplored. In Taraxacum kok-saghyz, a promising alternative rubber-producing species suitable for saline environments, understanding salt-responsive regulatory mechanisms is essential for improving rubber yield stability. In this study, 33 Dof genes were systematically identified from the Taraxacum kok-saghyz genome and designated TkDof1-TkDof33 according to their chromosomal distribution. The TkDof proteins exhibited substantial variation in amino acid length, molecular weight, and physicochemical properties. Phylogenetic analysis classified the TkDofs into four distinct clades, with a notable expansion of Group II, suggesting lineage-specific diversification. Conserved motif and gene structure analyses revealed a highly conserved Dof domain alongside clade-specific variations, indicating functional divergence within the family. Promoter analysis identified numerous cis-elements associated with light, phytohormones, and abiotic stresses, implying complex transcriptional regulation. Transcriptome and quantitative real-time polymerase chain reaction (qRT-PCR) analyses revealed pronounced tissue-specific and salt-responsive expression patterns, with several TkDof genes highly expressed in latex and roots. Among these, TkDof1 and TkDof24 were predominantly localized in the nucleus. Functional analyses further demonstrated that heterologous expression of TkDof1 and TkDof24 in yeast and Arabidopsis thaliana significantly enhanced salt stress tolerance. Collectively, this study provides a comprehensive characterization of the TkDof gene family and establishes a molecular framework for understanding their potential roles in natural rubber biosynthesis and abiotic stress adaptation in T. kok-saghyz.