A total of 26 BpDof genes were identified in birch via whole-genome analysis. The conserved Dof domain with a C(x)2C(x)21C(x)2C zinc finger motif was present in all BpDof proteins. These birch BpDofs were classified into four groups (A to D) according to the phylogenetic analysis of Arabidopsis thaliana Dof genes. BpDof proteins within the same group mostly possessed similar motifs, as detected by conserved motif analysis. The exon-intron analysis revealed that the structures of BpDof genes differed, indicating probable gene gain and lose during the BpDof evolution. The chromosomal distribution and synteny analysis showed that the 26 BpDofs were unevenly distributed on 14 chromosomes, and seven duplication events among six chromosomes were found. Cis-acting elements were abundant in the promoter regions of the 26 BpDof genes. qRT-PCR revealed that the expression of the 26 BpDof genes was differentially regulated by drought stress among roots, stems, and leaves. Most BpDof genes responded to drought stress, and BpDof4, BpDof11, and BpDof17- were significantly up-regulated. Therefore, plants overexpressing these three genes were generated to investigate drought stress tolerance. The BpDof4-, BpDof11-, and BpDof17--overexpressing plants showed promoted reactive oxygen species (ROS) scavenging capabilities and less severe cell damage, suggesting that they conferred enhanced drought tolerance in birch. This study provided an in-depth insight into the structure, evolution, expression, and function of the Dof gene family in plants.

	Year	Citations

About