Genome-wide identification of the Dof gene family in Carya illinoinensis and potential function analysis of CiDof22 in drought stress

DNA-binding with one finger (Dof) proteins are a unique class of plant-specific transcription factors that play a crucial role in regulating plant growth, development, and stress responses. Carya illinoinensis is an economically and ecologically important tree species. However, the functions of Dof transcription factors in this species remain unknown. In this study, 48 members of the Dof transcription factor family were identified from the C. illinoinensis genome and comprehensively investigated using bioinformatics. The analyses included phylogenetic relationships, chromosomal distribution, gene structure organization, conserved motif patterns, promoter cis-regulatory elements, interspecies collinearity, and evolutionary rate assessments. The integration of transcriptome data with qRT-PCR analysis revealed that CiDof22 exhibited a strong response to drought stress. CiDof22 was demonstrated as a nuclear-localized protein that lacks transcriptional self-activation activity in yeast. By transforming CiDof22 into Nicotiana benthamiana and using a 10% PEG6000 solution to simulate drought conditions for transient expression experiments, we found that both CiDof22 and drought-related genes were upregulated, confirming that CiDof22 significantly responds to drought stress. The findings of this study enhance our understanding of CiDof gene structure and function, while identifying promising gene candidates for improving drought resistance in C. illinoinensis through molecular breeding.