Genome-wide identification and expression analysis of the bZIP gene family in silver birch (Betula pendula Roth.)

Abstract

Basic Leu zipper (bZIP) genes play pivotal, versatile roles in abiotic or biotic stress responses and in other biological processes. Knowledge on the evolutionary relationships and patterns of gene expression of bZIP family members in woody plants, however, has been limited. Here we identified and characterized 47 BpbZIP genes across the silver birch (Betula pendula Roth.) genome. With reference to bZIP classifications for Arabidopsis thaliana, all BpbZIP proteins clustered among 10 groups in phylogeny. The bZIP domains were divided into five patterns based on intron positions and splicing phases. A total of 24 conserved motifs were detected in BpbZIPs with high group specificity. We also analyzed the protein structure of the BpAREB/ABF/ABI5 subfamily, the most important subfamily in the bZIP family. Expression analyses demonstrated that BpbZIP genes were widely involved in abscisic acid, salt, drought, and heat stress responses, with BpbZIP07/ABF4 and BpbZIP21/ABF2 most highly expressed. Our results on genome-wide identification, evolutionary relationships, gene structure, and motif and promoter element identification for BpbZIP family members in silver birch provide a comprehensive understanding of bZIP transcription factors in birch and will lead to a deeper understanding of their evolution and potential biological functions.

Keywords

Basic Leu zipper gene / Birch / Abscisic acid / Abiotic stress / Gene expression