# Comprehensive Identification of HD-Zip Family Genes in Coix lacryma-jobi L. and Their Potential Roles in Response to Abiotic Stress

## TL;DR

This study identifies 40 HD-Zip genes in Coix lacryma-jobi L. and explores their roles in stress response, particularly under salt, drought, and high-temperature conditions.

## Contribution

The first comprehensive identification and analysis of the HD-Zip gene family in Coix lacryma-jobi L., including their potential roles in abiotic stress response.

## Key findings

- Forty HD-Zip genes were identified in Coix lacryma-jobi L., grouped into four subfamilies with distinct gene structures and conserved motifs.
- ClHDZ4 showed significant upregulation under salt, drought, and high-temperature stress and enhanced yeast growth under these conditions when ectopically expressed.

## Abstract

HD-Zip (homeodomain-leucine zipper) transcription factors play a crucial role in plant growth, development, and stress response; however, the HD-Zip gene family of Coix lacryma-jobi L. has not been identified. In this study, a total of 40 HD-Zip gene family members were identified in the genome of Coix. According to phylogenetic analysis, the Coix HD-Zip gene was divided into four subfamilies (I–IV), of which the HD-Zip I subfamily can be further divided into five branches. Moreover, HD-Zip members of the same subfamily usually share similar gene structures and conserved motifs. The transcription factor binding site enrichment analysis showed that there are many motifs for binding with transcription factors such as ERF (Ethylene responsive factor), MYB (v-myb avian myeloblastosis viral oncogene homolog), and ARF (Auxin Response Factor) in the promoter region of the ClHDZ genes. The results of qPCR (Quantitative Polymerase Chain Reaction) and expression profile analysis showed that ClHD-Zip I genes showed different levels of expression under different stress treatments. Among them, ClHDZ4 was located in the nucleus, and its expression pattern was significantly upregulated under salt, drought, and high-temperature stress. In addition, ectopic expression of ClHDZ4 enhanced the growth of yeast strains under drought, salt, or high-temperature treatment. In summary, these results laid a foundation for further research on the resistance function of the Coix HD-Zip gene.