# GhTGA2, a Potential Key Regulator of Salt Stress Response: Insights from Genome-Wide Identification of TGA Family Genes Across Ten Cotton Species

## TL;DR

This study identifies and characterizes TGA genes in cotton, revealing GhTGA2 as a key regulator of salt stress tolerance, offering insights for breeding salt-resistant cotton.

## Contribution

The first genome-wide identification and functional analysis of TGA genes in ten cotton species, highlighting GhTGA2's role in salt stress response.

## Key findings

- 74 TGA homologous genes were identified across ten cotton species, showing conserved domains and five distinct evolutionary branches.
- GhTGA2 was found to be significantly upregulated under salt stress and its silencing reduced salt tolerance in cotton.
- TGA genes are implicated in growth regulation and stress adaptation through hormone-mediated signaling pathways in cotton.

## Abstract

Background: The TGACG-BINDING FACTORS (TGA) gene family, a key subgroup of bZIP transcription factors, mediates plant stress responses and developmental processes by binding to the as-1 cis-element in target gene promoters to regulate transcriptional activation or repression. Despite its functional significance, systematic characterization of TGA genes in cotton (Gossypium spp.) remains insufficient. Methods: In this study, we performed a comprehensive genome-wide identification and phylogenetic analysis of TGA members across 10 Gossypium species and verified the functions of candidate genes using VIGS technology. Results: A total of 74 TGA homologous genes with conserved DOG1 and bZIP domains were identified. Evolutionary analysis revealed that the cotton TGA gene family can be classified into five distinct branches, suggesting functional diversification. Functional prediction analyses indicated these genes in cotton growth regulation and stress adaptation, potentially through hormone-mediated signaling pathways. Expression profiling demonstrated both tissue-specific expression patterns and salt-stress responsiveness in Gossypium hirsutum TGA genes, and GhTGA2 exhibited the most significant up-regulated expression under salt stress. Virus-induced gene silencing (VIGS)-mediated GhTGA2 silencing significantly reduced the salt tolerance in cotton. Conclusions: The TGA gene family is involved in regulating cotton growth, development, and stress responses, and plays a critical role in mediating salt stress tolerance in cotton. Our results provide mechanistic insights into cotton stress adaptation and establish a valuable genetic resource for developing elite salt-tolerant cotton cultivars, with direct implications for sustainable cotton production.