# Genome-Wide Identification of the ABF/AREB/ABI5 Gene Family in Ziziphus jujuba cv. Dongzao and Analysis of Its Response to Drought Stress

## TL;DR

This study identifies and analyzes the ABF/AREB/ABI5 gene family in jujube, revealing their roles in drought stress and plant development.

## Contribution

The first genome-wide characterization of ZjABF genes in Ziziphus jujuba cv. Dongzao, revealing their structural and functional roles in abiotic stress.

## Key findings

- Seven ZjABF genes were identified and localized to five chromosomes with conserved bZIP domains.
- Phylogenetic analysis grouped ZjABF proteins into three clades, with distinct expression patterns in roots and fruits.
- Four ZjABF genes showed differential expression under drought stress, with ZjABF2 being highly responsive.

## Abstract

Abscisic acid (ABA), a pivotal phytohormone regulating plant growth and stress adaptation, orchestrates abiotic stress responses through the ABA-responsive element-binding factors ABF/AREB/ABI5. Nevertheless, the functional characterization of ABF/AREB/ABI5 homologs in Z. jujuba cv. Dongzao remains unexplored. In this study, we identified seven ZjABF genes distributed across five chromosomes. Domain analyses revealed high structural conservation, particularly within the basic leucine zipper (bZIP) DNA-binding domain. Subcellular localization confirmed nuclear targeting of all seven ZjABF proteins. Phylogenetic classification resolved these factors into three clades (A–C). Cis-regulatory element profiling implicated the involvement of the ZjABFs in hormone signaling, abiotic stress transduction, and photoregulatory pathways. Synteny analyses identified three segmental duplication events within the gene family. Tissue-specific expression patterns indicated critical roles for ZjABF2 and ZjABF3 in fruit maturation, and most of the ABF/AREB/ABI5 genes were highly expressed in the root. Under drought stress, four ZjABF genes exhibited differential expression, with ZjABF2 demonstrating pronounced sensitivity. These findings establish a molecular framework for understanding ZjABF-mediated abiotic stress responses in non-model woody perennials.