# Comprehensive Analysis of the Poplar DREB A4 Subfamily and the Role of PtrDREB4 in Response to Drought Stress

## TL;DR

This study explores the DREB A4 gene subfamily in poplar and shows that one gene, PtrDREB4, helps plants tolerate drought stress.

## Contribution

The study identifies and functionally characterizes the DREB A4 subfamily in poplar, revealing the role of PtrDREB4 in drought tolerance.

## Key findings

- 29 DREB A4 genes were identified in the poplar genome, with 19 undergoing segmental duplication.
- PtrDREB4 overexpression in Arabidopsis and yeast enhanced drought tolerance.
- DREB A4 genes showed distinct expression patterns and stress-related promoter elements.

## Abstract

The dehydration response element binding protein (DREB) family of the AP2/ERF superfamily functions as a key regulatory component in plant adaptation to water-deficit conditions. However, studies on the DREB A4 subfamily in poplar (Populus trichocarpa) are insufficient. In this study, members of the DREB A4 subgroup in poplar were identified and analyzed via bioinformatic analysis. A pCAMBIA-2300-PtrDREB4 expression vector was constructed and transformed into Arabidopsis, followed by phenotypic analysis of transgenic plant in response to drought stress. A total number of 29 DREB A4 members were identified in the poplar genome. Synteny analysis revealed that 19 gene pairs went through segmental duplication at least 12.84 million years ago. Their promoter regions were enriched with cis-elements related to stress resistance, hormone regulation, and growth and development. Upstream regulator analysis of poplar DREB A4 genes identified 425 transcription factor genes, which belonged to 39 families. Gene expression analysis demonstrated distinct expression patterns of DREB A4 genes in leaves, roots and stems with a notable response to drought stress. Ectopic expression of PtrDREB4 in yeast and Arabidopsis increased the drought tolerance of transformants, indicating the positive role of PtrDREB4 in response to drought stress. These findings collectively established a theoretical foundation for further functional exploration of DREB A4 genes in poplar.