Whole-Genome Characterization of Rosa Chinensis AP2/ERF Transcription Factors and Analysis of Negative Regulator RcDREB2B in Arabidopsis

Abstract Background: Rose (Rosa chinensis) is a traditional famous flower with valuable ornamental characteristics. However, drought stress restricts its growth and development, leading to abnormal phenotype. APETALA2/ethylene-responsive factor (AP2/ERF) proteins are a kind of transcription factor (TF) protein groups in the plant kingdom, which are crucially involved in the growth and stress responses of most plants. Results: Our investigation focused on exploring the genome of rose and we discovered 135 apparent AP2/ERF TFs. Phylogenic analyses revealed that RcAP2/ERF genes are categorized into DREB, Soloist, AP2, and ERF subfamilies, and further classified these into 17 groups. Analysis of the gene structure revealed that the introns ranged from 0 to 9 in number. Pattern examination demonstrated that the RcAP2/ERF predominantly had typical AP2 domains, of which the 2nd motif is the most ubiquitous. Distributions of cis-acting elements showed members of the AP2/ERF family are involved in growth development and stress response in rose species. We carried out a distribution mapping of the seven rose chromosomes which revealed that AP2/ERF class genes are dispersed among all seven chromosomes. Additionally, we isolated a novel DREB A-2 subgroup gene and named it RcDREB2B. RcDREB2B transcript accumulation was repressed under mild drought and severe drought stress in the root samples of rose. RcDREB2B was targeted to the nucleus and exhibited transactivation in yeast cells. Overexpression of RcDREB2B resulted in enhanced sensitivity to high salt concentration, ABA, and PEG at the germination and post-germination stages. Twelve putative osmotic and ABA-related genes were impaired in RcDREB2B-overexpressing plants. Conclusion: The results provide comprehensive information regarding the gene structure, phylogenic, and distribution of rose AP2/ERF family and shed insight into the complex transcriptional gene regulation of RcAP2/ERF. Findings in this study would also contribute to further understanding of the RcDREB2B gene in rose.