# Identification and Expression Profiles of Xyloglucan Endotransglycosylase/Hydrolase Family in Response to Drought Stress in Larix kaempferi

## TL;DR

This study identifies 16 XTH genes in larch and shows how they respond to drought stress in different plant parts, helping understand their role in plant resilience.

## Contribution

The study provides new insights into the organ-specific expression and functional roles of XTH genes in larch under drought stress.

## Key findings

- LkXTH genes are divided into three subfamilies with conserved motifs and structural features.
- Several LkXTH genes show increased expression in roots, leaves, and stems under drought stress.
- Heterologous expression of LkXTH1 and LkXTH17 in yeast enhances drought tolerance.

## Abstract

Xyloglucan endotransglucosylase/hydrolase (XTH) is a crucial enzyme in plant cell wall remodeling, which contributes to plant growth, development, and stress response. Based on the transcriptome data of Larix kaempferi, this study identified and analyzed 16 XTH genes. Sequence alignment and phylogenetic analysis indicated that the LkXTH gene family can be divided into three subfamilies, namely the Early Diverging Group, Group I/II, and Group III, all of which share highly conserved motifs and structural features. Expression profiling demonstrated that LkXTH genes are actively expressed in the roots, stems, and leaves of L. kaempferi. Under drought stress, the expression of LkXTH1, LkXTH2, LkXTH3, LkXTH4, LkXTH6, LkXTH14, LkXTH15, LkXTH17, and LkXTH18 increased rapidly in roots. Meanwhile, the expression levels of LkXTH5, LkXTH7, LkXTH8, and LkXTH13 exhibited significant upregulation in leaves. Notably, LkXTH11 and LkXTH16 significantly increased in both roots and leaves, with a more pronounced increase in leaves, but LkXTH10 displayed significant upregulation in the stems. Furthermore, the heterologous expression of LkXTH1 and LkXTH17 in yeast significantly enhances drought tolerance. These findings indicate that individual LkXTH genes exhibit distinct organ-specific responses to drought stress, thereby advancing our understanding of their functional roles in larch drought response.