# The Function of RcAG2 and RcFUL in the Flower Shape Change of Rosa chinensis ‘Viridiflora’

## TL;DR

This study identifies two genes, RcAG2 and RcFUL, that influence flower shape changes in Rosa chinensis 'Viridiflora', offering insights into floral development.

## Contribution

The study reveals the functional roles of RcAG2 and RcFUL in floral organ identity and development in Rosa chinensis.

## Key findings

- RcAG2 and RcFUL are involved in floral organ development and exhibit distinct phenotypic effects when overexpressed in Arabidopsis.
- The genes lack signal peptides and transmembrane domains but contain MADS-box domains and phosphorylation sites.
- Overexpression of RcFUL resulted in leaf-like petals and increased sepal number, while RcAG2 caused petal reduction and stamen exposure.

## Abstract

The floral morphology of Rosa chinensis significantly influences its ornamental value. However, the molecular mechanisms underlying specific floral types remain poorly understood. Viridiflora, a stable genetic variant of R. chinensis, exhibits homeotic transformation of floral organs into sepal-like structures, providing a valuable model for studying floral organ identity and development. In this study, Viridiflora was compared with Old Blush to elucidate floral development through morphological observation, transcriptomic profiling, and functional genetics. Four distinct developmental stages were defined, encompassing the formation of sepal, petal, stamen, and pistil primordia. Transcriptome analysis identified candidate genes associated with the Viridiflora phenotype, among which RcAGAMOUS2 (RcAG2) and RcFRUITFULL (RcFUL) were selected for in-depth functional characterization. The proteins encoded by these two genes are hydrophilic, lack signal peptides and transmembrane domains, and contain multiple phosphorylation sites. They feature typical MADS-box family domains and show close phylogenetic affinity to Rosa rugosa. Subcellular localization showed their nuclear presence. Heterologous overexpression of RcAG2 and RcFUL in Arabidopsis resulted in notable phenotypic alterations: RcAG2 caused petal reduction and stamen exposure, while RcFUL led to greenish, leaf-like petals with pigmentation gradients, increased sepal number, and failed seed set. Conclusion: These results suggest that RcAG2 and RcFUL play key roles in floral organ development through genetic regulation, providing a theoretical foundation for further research on floral development in R. chinensis.