Search

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.

The PEBP gene family plays a significant role in regulating flower development and formation. To understand its function in Dendrobium chrysotoxum and D. nobile flowering, we identified 22 PEBP genes (11 DchPEBP s and 11 DnoPEBP s) from both species. We conducted analyses on their conserved domains and motifs, phylogenetic relationships, chromosome distribution, collinear correlation, and cis elements. The classification results showed that the 22 PEBP s were mainly divided into three clades, as follows: FT, MFT, and TFL1. A sequence analysis showed that most PEBP proteins contained five conserved domains, while a gene structure analysis revealed that 77% of the total PEBP genes contained four exons and three introns. The promoter regions of the 22 PEBP s contained several cis elements related to hormone induction and light response. This suggests these PEBP s could play a role in regulating flower development by controlling photoperiod and hormone levels. Additionally, a collinearity analysis revealed three pairs of duplicate genes in the genomes of both D. chrysotoxum and D. nobile . Furthermore, RT-qPCR has found to influence the regulatory effect of DchPEBP s on the development of flower organs (sepals, petals, lip, ovary, and gynostemium) during the flowering process (bud, transparent stage, and initial bloom). The results obtained imply that DchPEBP8 and DchPEBP9 play a role in the initial bloom and that DchPEBP7 may inhibit flowering processes. Moreover, DchPEBP9 may potentially be involved in the development of reproductive functionality. PEBP s have regulatory functions that modulate flowering. FT initiates plant flowering by mediating photoperiod and temperature signals, while TFL1 inhibits flowering processes. These findings provide clues for future studies on flower development in Dendrobium.

The TCP gene family are plant-specific transcription factors that play important roles in plant growth and development. Dendrobium chrysotoxum , D. nobile , and D. huoshanense are orchids with a high ornamental value, but few studies have investigated the specific functions of TCP s in Dendrobium flower development. In this study, we used these three Dendrobium species to analyze TCP s, examining their physicochemical properties, phylogenetic relationships, gene structures, and expression profiles. A total of 50 TCP s were identified across three Dendrobium species; they were divided into two clades-Class-I (PCF subfamily) and Class-II (CIN and CYC/TB1 subfamilies)-based on their phylogenetic relationships. Our sequence logo analysis showed that almost all Dendrobium TCP s contain a conserved TCP domain, as well as the existence of fewer exons, and the cis -regulatory elements of the TCP s were mostly related to light response. In addition, our transcriptomic data and qRT-PCR results showed that DchTCP2 and DchTCP13 had a significant impact on lateral organs. Moreover, changes in the expression level of DchTCP4 suggested its important role in the phenotypic variation of floral organs. Therefore, this study provides a significant reference for the further exploration of TCP gene functions in the regulation of different floral organs in Dendrobium orchids.

The small plant-specific YABBY gene family plays key roles in diverse developmental processes in plants. Dendrobium chrysotoxum , D. huoshanense , and D. nobile are perennial herbaceous plants belonging to Orchidaceae with a high ornamental value. However, the relationships and specific functions of the YABBY genes in the Dendrobium species remain unknown. In this study, six DchYABBY s, nine DhuYABBY s, and nine DnoYABBY s were identified from the genome databases of the three Dendrobium species, which were unevenly distributed on five, eight, and nine chromosomes, respectively. The 24 YABBY genes were classified into four subfamilies (CRC/DL, INO, YAB2, and FIL/YAB3) based on their phylogenetic analysis. A sequence analysis showed that most of the YABBY proteins contained conserved C2C2 zinc-finger and YABBY domains, while a gene structure analysis revealed that 46% of the total YABBY genes contained seven exons and six introns. All the YABBY genes harbored a large number of Methyl Jasmonate responsive elements, as well as anaerobic induction cis -acting elements in the promoter regions. Through a collinearity analysis, one, two, and two segmental duplicated gene pairs were identified in the D. chrysotoxum , D. huoshanense , and D. nobile genomes, respectively. The Ka/Ks values of these five gene pairs were lower than 0.5, indicating that the Dendrobium YABBY genes underwent negative selection. In addition, an expression analysis revealed that DchYABBY2 plays a role in ovary and early-stage petal development, while DchYABBY5 is essential for lip development and DchYABBY6 is crucial for early sepal formation. DchYABBY1 primarily regulates sepals during blooming. Furthermore, there is the potential involvement of DchYABBY2 and DchYABBY5 in gynostemium development. The results of a comprehensive genome-wide study would provide significant clues for future functional investigations and pattern analyses of YABBY genes in different flower parts during flower development in the Dendrobium species.

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]