Genome-Wide Identification of WOX Gene Family in Chimonanthus praecox and a Functional Analysis of CpWUS

<i>Chimonanthus praecox</i>, also known as wintersweet, is a traditional ornamental plant in China. It blooms during the cold winter months and emits a long-lasting fragrance. The WUSCHEL-related homeobox (WOX) transcription factor family is a plant-specific family of homeodomain (HD) transcription factors that plays diverse roles in plant development. We identified 13 <i>WOX</i> family genes (<i>CpWOX1-CpWOX12</i> and <i>CpWUS</i>) and systematically analysed their physicochemical properties, evolutionary relationships, conserved domains, and expression regulation characteristics. The subcellular localization prediction indicates that all CpWOX proteins are localized in the nucleus and contain a conserved homeobox domain, with the WUS clade specifically containing a WUS-box motif. Phylogenetic analysis revealed that these genes are divided into three evolutionary branches: the WUS, ancient, and intermediate clades. Promoter analysis suggests that <i>CpWOX</i> genes may be involved in hormone responses, abiotic stress, developmental regulation, and encodes a nuclear-localised protein with self-activating activity. It is highly expressed in the stamen and root and is induced by low and high temperatures, salt stress, and methyl jasmonate. This study revealed the evolutionary characteristics of the WOX family genes in wintersweet and the function of <i>CpWUS</i> in regulating flowering time and root development, providing a theoretical basis for understanding the developmental regulatory mechanisms in wintersweet.