Histone deacetylase family in balloon flower Platycodon grandiflorus: Genome-wide identification and expression analysis under waterlogging stress

Histone deacetylases (HDACs) play a pivotal role in epigenetic regulation, affecting the structure of chro- matin and gene expression across different stages of plant development and in response to environmental stresses. Although the role of HDACs in Arabidopsis and rice has been focused on in extensive research, the role of the HDAC gene family in various medicinal plants remains unclear. In the genome of the balloon flower Platycodon grandiflorus, we identified 10 putative P. grandiflorus HDAC (PlgHDAC) proteins, which were classified into the three families (RPD3/HDA1, SIR2, and HD2 HDAC families) based on their domain compositions. These HDACs were predicted to be localized in various cellular compartments, indicating that they have diverse functions. In addition, the tissue- specific expression profiles of PlgHDACs differed across different plant tissues, indicating that they are involved in various developmental processes. Furthermore, the expression levels of all PlgHDACs were upregulated in leaves after waterlogging treatment, implying their potential role in coping with waterlogging-induced stress. Overall, our findings provide a comprehensive foundation for further research into the epigenetic regulation of PlgHDACs, and particularly, on their functions in response to environmental stresses such as waterlogging. Understanding the roles of these HDACs in the development and stress responses of balloon flower could have significant implications for improving crop yield and the quality of this important medicinal plant.