# Identification of the FtsH gene family in chrysanthemums and functional analysis of CmFtsH-15 under cadmium stress

## TL;DR

This study identifies and analyzes the FtsH gene family in chrysanthemums, focusing on how CmFtsH-15 helps plants tolerate cadmium stress.

## Contribution

The study provides the first comprehensive analysis of the FtsH gene family in Chrysanthemum morifolium and identifies CmFtsH-15 as a key gene for cadmium tolerance.

## Key findings

- CmFtsH-15 overexpression reduces cadmium accumulation and oxidative damage in chrysanthemums.
- CmFtsH-15 interacts with CmHSP70 to regulate stress response.
- The 32 CmFtsH genes show uneven chromosomal distribution and lineage-specific evolution.

## Abstract

The FtsH gene family encodes ATP-dependent zinc metalloproteases essential for protein quality control, organelle homeostasis, and stress response in plants. Nevertheless, research on the FtsH gene family in Chrysanthemum morifolium is limited. This study identified 32 CmFtsH genes through bioinformatics approaches and systematically analyzed their family members. Phylogenetic analysis clarified their evolutionary relationships, while chromosomal localization, sequence alignment, and promoter cis-element prediction were utilized to analyze gene characteristics. Tissue-specific expression profiling identified key genes, and overexpression experiments confirmed the cadmium (Cd) tolerance of the candidate gene CmFtsH-15. The analysis indicated a close evolutionary relationship with Asteraceae plants such as lettuce and sunflower, demonstrating lineage-specific differentiation. The 32 CmFtsH genes are unevenly distributed across 16 chromosomes, exhibiting significant differences in sequence length and motif composition. Promoter regions are abundant in stress and hormone response elements, indicating potential involvement in abiotic stress adaptation. CmFtsH-15 is significantly expressed in leaves, and its overexpression alleviates oxidative damage by reducing Cd accumulation, enhancing antioxidant activity, and decreasing malondialdehyde content, thereby enhancing Cd tolerance in transgenic lines. Furthermore, CmFtsH-15 interacts with the heat shock protein CmHSP70, suggesting a synergistic regulation of stress response. This study systematically explored the FtsH gene family in Chrysanthemum, highlighting the protective role of CmFtsH-15 under Cd stress, thus providing a promising candidate for developing Cd-resistant germplasm resources.