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The WUSCHEL-related homeobox (WOX) transcription factor plays a vital role in stem cell maintenance and organ morphogenesis, which are essential processes for plant growth and development. Dendrobium chrysotoxum , D. huoshanense , and D. nobile are valued for their ornamental and medicinal properties. However, the specific functions of the WOX gene family in Dendrobium species are not well understood. In our study, a total of 30 WOX genes were present in the genomes of the three Dendrobium species (nine DchWOXs, 11 DhuWOXs, and ten DnoWOXs). These 30 WOXs were clustered into ancient clades, intermediate clades, and WUS/modern clades. All 30 WOXs contained a conserved homeodomain, and the conserved motifs and gene structures were similar among WOXs belonging to the same branch. D. chrysotoxum and D. huoshanense had one pair of fragment duplication genes and one pair of tandem duplication genes, respectively; D. nobile had two pairs of fragment duplication genes. The cis -acting regulatory elements (CREs) in the WOX promoter region were mainly enriched in the light response, stress response, and plant growth and development regulation. The expression pattern and RT-qPCR analysis revealed that the WOXs were involved in regulating the floral organ development of D. chrysotoxum . Among them, the high expression of DchWOX3 suggests that it might be involved in controlling lip development, whereas DchWOX5 might be involved in controlling ovary development. In conclusion, this work lays the groundwork for an in-depth investigation into the functions of WOX genes and their regulatory role in Dendrobium species' floral organ development.

ZF-HD transcription factors, which are unique to land plants, are involved in the regulation of abiotic stress response and related signaling pathways, and play a crucial role in plant growth and development. Dendrobium is one of the largest genera of orchids, with a high ornamental and ecological value. However, the specific functions of the ZF-HDs in Dendrobium remain unknown. In this study, we identified a total of 53 ZF-HDs from D. chrysotoxum (17), D. catenatum (23), and D. huoshanense (13), and analyzed their physicochemical properties, phylogenetic relationships, chromosomal locations, protein structures, conserved motifs, and expression patterns. The phylogenetic relationships revealed that 53 ZF-HDs were classified into six subfamilies (ZHDI–V and MIF), and all ZF-HD proteins contained motif 1 and motif 4 conserved domains, while a minority of these proteins had exons. The analysis of cis-elements in the promoters of ZF-HDs from three Dendrobium species showed that growth- and development-related elements were the most prevalent, followed by hormone response and abiotic stress response elements. Through collinearity analysis, 14 DchZF-HDs were found to be collinear with DhuZF-HDs, and 12 DchZF-HDs were found to be collinear with DcaZF-HDs. Furthermore, RT-qPCR analysis revealed that DchZF-HDs play a regulatory role in the development of lateral organs during the flowering process. The results indicated that DchZHD2 plays a role in the unpigmented bud stage, while DchMIF8 and DchZHD16 play significant roles during the pigmented bud and initial bloom stages. Hence, this study provides a crucial basis for further exploring ZF-HDs functions in regulating the floral organs of orchids. [ABSTRACT FROM AUTHOR]