# Genome-Wide Analysis of GRETCHEN HAGEN3 Genes and Characterization of IAA-Amido Synthetase Gene CsGH3.1 in Rhizome Proliferation in Cymbidium sinense ‘Qijianbaimo’

## TL;DR

This study explores GH3 genes in Cymbidium sinense, focusing on CsGH3.1's role in rhizome growth and auxin regulation.

## Contribution

The study identifies and characterizes CsGH3.1 as a key regulator of rhizome proliferation in Cymbidium sinense.

## Key findings

- Seven GH3 genes were identified and classified into two subfamilies in Cymbidium sinense.
- CsGH3.1 and CsGH3.2 are upregulated by NAA, suggesting roles in auxin homeostasis during rhizome proliferation.
- Overexpression of CsGH3.1 in Arabidopsis reduced growth and callus proliferation, confirming its regulatory role.

## Abstract

This study systematically identified and functionally analyzed the GRETCHEN HAGEN 3 (GH3) gene family in Cymbidium sinense ‘Qijianbaimo’ (CSQ). Seven GH3 genes (CsGH3.1–CsGH3.7) were identified using genomic and transcriptomic data. Phylogenetic analysis revealed that CsGH3s are divided into two subfamilies, with CsGH3.1–CsGH3.4 belonging to subfamily II and CsGH3.5–CsGH3.7 to subfamily I. Gene structure analysis showed that CsGH3s contain one to four exons, and their promoter regions feature auxin and jasmonic acid response elements. CsGH3.1 and CsGH3.2 were significantly upregulated in response to naphthaleneacetic acid (NAA) during rhizome proliferation, indicating their pivotal role in auxin homeostasis regulation. The overexpression of CsGH3.1 in Arabidopsis led to restricted growth and a significant reduction in callus proliferation rates, further confirming its role in regulating cell proliferation and auxin homeostasis. This study provides new insights into the function of the CsGH3.1 gene in the rhizome proliferation of Cymbidium sinense and lays a foundation for future research on the molecular mechanism of micropropagation in Cymbidium.