# Identification, Characterization and Expression Profiles of Xylogen-like Gene Family in Kiwifruit in Different Developmental Tissues and Under Various Abiotic Stresses

## TL;DR

This study identifies and analyzes 28 XYLP genes in kiwifruit, revealing their roles in growth, development, and stress responses.

## Contribution

Systematic identification and characterization of the XYLP gene family in kiwifruit, including their expression and stress response roles.

## Key findings

- 28 AcXYLP genes were identified and grouped into five clades through phylogenetic analysis.
- AcXYLP genes are involved in growth, development, and abiotic stress responses, with three genes (AcXYLP13, AcXYLP15, AcXYLP27) playing central roles.
- Segmental duplication was the main driver of AcXYLP gene family expansion.

## Abstract

This study investigates the XYLP gene family in kiwifruit, focusing on its roles in growth, development, phytohormone response, and abiotic stress. A total of 28 AcXYLP gene family members were identified and categorized into five clades. Most AcXYLPs are alkaline, predominantly hydrophobic, and tend to be structurally unstable. All the AcXYLPs are in silico predicted to be localized to the cell membrane. The 28 AcXYLP genes exhibit uneven distribution, with segmental duplication as the major driving force during gene family expansion. Transcriptome analysis, complemented by qRT-PCR validation, confirmed the involvement of XYLP genes in organ development, fruit ripening, and responses to phytohormones and abiotic stresses. This study lays a foundation for future investigations into the biological functions of XYLP genes in kiwifruit.

The XYLP family is reported to be essential for the regulation of growth and development, mediating plant hormone signals, and promoting adaptation to environmental stresses across various plant species. Although the XYLP family in Actinidia chinensis (kiwifruit) enhances the understanding of developmental processes and abiotic stress responses, a systematic analysis of this gene family remains lacking. In this study, 28 AcXYLP genes were identified in the kiwifruit genome, which were classified into five clades based on a phylogenetic tree. Collinearity analysis revealed that the expansion of AcXYLP genes was predominantly influenced by segmental genome duplication events. Gene ontology and protein–protein interaction network analysis indicated that AcXYLP genes were involved in pathways related to plant growth, developmental process, and abiotic stresses responses. The promoter regions harboring cis-acting elements associated with plant growth and development, phytohormones, and stress responses, highlighting the significant roles of the AcXYLP gene family. Expression profile analysis of 28 AcXYLP genes in different tissues revealed their tissue-specific functions. Notably, AcXYLP13, AcXYLP15 and AcXYLP27 were identified as top-ranked nodes in STRING-predicted network protein involved in plant growth and abiotic stress responses, indicating their central roles in coordinating developmental signaling and stress responses. This study facilitated further exploration of the functional characteristics of AcXYLP genes.