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Since the time of Darwin, biologists have studied the origin and evolution of the Orchidaceae, one of the largest families of flowering plants. In the last two decades, the extreme diversity and specialization of floral morphology and the uncoupled rate of morphological and molecular evolution that have been observed in some orchid species have spu...
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... orchids, the number of characterized genes belonging to the C and D classes is smaller than those of the other classes (Table 1, Fig. 4). ...Context 2
... class B genes characterized in orchids are the most numerous and thoroughly studied compared with those of the other classes (Table 1, Fig. 4). A feature common to a high number of the class B MADS-box orchid genes is the expan- sion of their expression profile into the first whorl of floral organs that may be responsible for the development of peta- loid sepals in orchids (Fig. 3B). ...Similar publications
Among the major distance senses of vertebrates, the ear is unique in its complex morphological changes during evolution. Conceivably, these changes enable the ear to adapt toward sensing various physically well-characterized stimuli. This review develops a scenario that integrates sensory cell with organ evolution. We propose that molecular and cel...
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... Orchidaceae is one of the largest and most evolutionary families in the plant kingdom [1]. The flower of the orchid has evolved in concert with insects to form highly specialized structures, so the orchid is considered to be one of the ideal plants for the study of floral developmental biology in monocotyledons. ...
Orchid flowers have evolved in concert with pollinators to form highly specialized structures resulting in zygomorphy. In dicotyledons, it is widely accepted that CYC-like genes are involved in the dorsoventral polarity establishment of flowers, which determines the development of zygomorphic flowers. However, the function of TCP transcription factors involved in orchid floral development is rarely known. Here, we found 15 unigenes with TCP domain (EpTCPs) from the previously reported Erycina pusilla unigene database. The expression patterns of EpTCPs in various tissues and different floral organs were successively detected by quantitative real-time PCR. The results revealed that the CYC-like gene (EpTCP25) and CIN-like genes (EpTCP11 and EpTCP26) were highly expressed in inflorescences but lowly expressed in leaves and roots. What is more, these three genes were expressed relatively high in the dorsal labellum, and EpTCP26 showed differential expression along the dorsoventral polarity of tepals, which was high in the dorsal and low in the ventral. Ectopic expression of EpTCP25 in Arabidopsis repressed primary root growth and delayed flowering. EpTCP26 overexpression in Arabidopsis promoted primary root growth and leaf growth. In contrast, EpTCP11 overexpression repressed primary root growth and changed the radially symmetric flower to a bilaterally symmetric flower by inhibiting the elongation of one or two adjacent petals. In addition, the homeotic transition of floral organs is generated when these genes are ectopically expressed in Arabidopsis, suggesting their roles in floral morphogenesis. Altogether, our results indicate that CIN-like genes would be associated with the unique flower pattern development of Erycina pusilla.
... Orchid is one of the most diverse and geographically widespread families of angiosperms. Their evolutionary success may be attributed to various factors, including epiphytism, exceptional adaptive capacity in different habitats, highly specialized pollination strategies, and diverse flower morphology (Aceto and Gaudio 2011;Cozzolino and Widmer 2005;Tremblay et al. 2005). The lip is a central organ in orchid pollination because of its strikingly distinct morphology and its direct opposition to the gynostemium. ...
The molecular basis of orchid flower development involves a specific regulatory program in which MADS-box transcription factors play a central role. The recent ‘perianth code’ model hypothesizes that two types of higher-order heterotetrameric complexes, namely SP complex and L complex, play pivotal roles in the orchid perianth organ formation. Therefore, we explored their roles and searched for other components of the regulatory network.
Through the combined analysis for transposase-accessible chromatin with high-throughput sequencing and RNA sequencing of the lip-like petal and lip from Phalaenopsis equestris var.trilip, transcription factor-(TF) genes involved in lip development were revealed. PeNAC67 encoding a NAC-type TF and PeSCL23 encoding a GRAS-type TF were differentially expressed between the lip-like petal and the lip. PeNAC67 interacted with and stabilized PeMADS3, which positively regulated the development of lip-like petal to lip. PeSCL23 and PeNAC67 competitively bound with PeKAN2 and positively regulated the development of lip-like petal to petal by affecting the level of PeMADS3. PeKAN2 as an important TF that interacts with PeMADS3 and PeMADS9 can promote lip development. These results extend the ‘perianth code’ model and shed light on the complex regulation of orchid flower development.
Supplementary Information
The online version contains supplementary material available at 10.1186/s43897-023-00079-8.
... Normal sepal development is crucial for successful reproductive development. As the E class genes, the SEP MADSbox transcription factors are involved in the sepal identity in the ABCDE model and the quartet model during floral organ development [60,65]. In Arabidopsis, four SEP MADS-box genes, SEP1-4, cooperatively specify floral organ identity [31,32]. ...
MADS-box transcription factors have crucial functions in numerous physiological and biochemical processes during plant growth and development. Previous studies have reported that two MADS-box genes, SlMBP21 and SlMADS1, play important regulatory roles in the sepal development of tomato, respectively. However, the functional relationships between these two genes are still unknown. In order to investigate this, we simultaneously studied these two genes in tomato. Phylogenetic analysis showed that they were classified into the same branch of the SEPALLATA (SEP) clade. qRT-PCR displayed that both SlMBP21 and SlMADS1 transcripts are preferentially accumulated in sepals, and are increased with flower development. During sepal development, SlMBP21 is increased but SlMADS1 is decreased. Using the RNAi, tomato plants with reduced SlMBP21 mRNA generated enlarged and fused sepals, while simultaneous inhibition of SlMBP21 and SlMADS1 led to larger (longer and wider) and fused sepals than that in SlMBP21-RNAi lines. qRT-PCR results exhibited that the transcripts of genes relating to sepal development, ethylene, auxin and cell expansion were dramatically changed in SlMBP21-RNAi sepals, especially in SlMBP21-SlMADS1-RNAi sepals. Yeast two-hybrid assay displayed that SlMBP21 can interact with SlMBP21, SlAP2a, TAGL1 and RIN, and SlMADS1 can interact with SlAP2a and RIN, respectively. In conclusion, SlMBP21 and SlMADS1 cooperatively regulate sepal development in tomato by impacting the expression or activities of other related regulators or via interactions with other regulatory proteins.
... Orchidaceae is one of the largest families of flowering plants (Cozzolino and Widmer, 2005). Most orchid species exhibit extreme diversity and specialization in perianth morphology, which is closely related to MADS-box transcription factors, as described in the "orchid code" proposed by Aceto and Gaudio (2011) and the "P code" proposed by Hsu et al. (2015). In Phalaenopsis equestris, CIN-TCPs could act as dual-function transcription factors by regulating petal and leaf size (Lin et al., 2016). ...
TCP is a widely distributed, essential plant transcription factor that regulates plant growth and development. An in-depth study of TCP genes in Dendrobium nobile, a crucial parent in genetic breeding and an excellent model material to explore perianth development in Dendrobium, has not been conducted. We identified 23 DnTCP genes unevenly distributed across 19 chromosomes and classified them as Class I PCF (12 members), Class II: CIN (10 members), and CYC/TB1 (1 member) based on the conserved domain and phylogenetic analysis. Most DnTCPs in the same subclade had similar gene and motif structures. Segmental duplication was the predominant duplication event for TCP genes, and no tandem duplication was observed. Seven genes in the CIN subclade had potential miR319 and -159 target sites. Cis-acting element analysis showed that most DnTCP genes contained many developmental stress-, light-, and phytohormone-responsive elements in their promoter regions. Distinct expression patterns were observed among the 23 DnTCP genes, suggesting that these genes have diverse regulatory roles at different stages of perianth development or in different organs. For instance, DnTCP4 and DnTCP18 play a role in early perianth development, and DnTCP5 and DnTCP10 are significantly expressed during late perianth development. DnTCP17, 20, 21, and 22 are the most likely to be involved in perianth and leaf development. DnTCP11 was significantly expressed in the gynandrium. Specially, MADS-specific binding sites were present in most DnTCP genes putative promoters, and two Class I DnTCPs were in the nucleus and interacted with each other or with the MADS-box. The interactions between TCP and the MADS-box have been described for the first time in orchids, which broadens our understanding of the regulatory network of TCP involved in perianth development in orchids.
... Therefore, they are ideal for studying biodiversity and evolution. Orchids have specialized flower organs, mainly including three sepals, two petals, one highly specialized lip, and a gynoecium [19]. Dendrobium, the second largest genus of Orchidaceae, contains approximately 1450 species, the majority of which are characterized by a fleshy stem with abundant polysaccharides and grow in diverse habitats [20]. ...
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 TCPs in Dendrobium flower development. In this study, we used these three Dendrobium species to analyze TCPs, examining their physicochemical properties, phylogenetic relationships, gene structures, and expression profiles. A total of 50 TCPs 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 TCPs contain a conserved TCP domain, as well as the existence of fewer exons, and the cis-regulatory elements of the TCPs 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.
... Flowers have played a significant role in the field of plant developmental biology since the discovery of Mendel's laws, and research has focused on various aspects including the process of flowering, the morphology and development of flowers, and their color and scent (Alvarez-Buylla et al., 2010;Li et al., 2021a;Serena and Luciano, 2011). Orchids exhibit a rich diversity of floral structures, highly specialized morphological traits, as well as a wide range of colors and markings (Ai et al.;Li et al., 2022b). ...
Orchidaceae is one of the largest monocotyledon families and contributes significantly to worldwide biodiversity, with value in the fields of landscaping, medicine, and ecology. The diverse phenotypes and vibrant colors of orchid floral organs make them excellent research objects for investigating flower development and pigmentation. In recent years, a number of orchid genomes have been published, revealing the molecular basis of flower development and color presentation. In this article, we review transcription factors, the structural genes responsible for the floral pigment synthesis pathways, the molecular mechanisms of flower morphogenesis, and the potential relationship between flower type and flower color. This study provides a theoretical reference for the research on molecular mechanisms related to flower morphogenesis and color presentation, genetic improvement, and new variety creation in orchids.
... Although it has a vast consistency in its floral structure, they have a wide variety in the structural features of its lip and column. The lip is distinguished from the other tepals by its distinctive shape and colour pattern, as well as its ornate spurs, calli, and glands [2] . ...
... Applications of MF on plantlets have affected the proliferation of plants, as well as the growth of roots and shoots and photosynthesis. Coir fibres are utilised by tissue culture media to facilitate the straightforward in vitro germination of orchid seeds [2] . To propagate exotic variations to achieve translational success, many additional biotechnological approaches are currently being utilised. ...
Orchids are well known for their distinctive growth pattern, which adds to their popularity as aesthetic plants. Orchids are the collection of most varied and extensive group of flowering plants. These are produced commercially all over the world and with the advancements in biotechnological approaches, flower's natural life and aroma improved over the time. Orchid, the first and foremost floricultural crop was the driving force for establishment of flower business in India. The recent progress in biotechnology has contributed to betterment and development of flower type that previously are considered as exotic or foreign. Progressing from traditional breeding methods, plant tissue culture approaches, and the evolution of biotechnological interventions all aid in the cumulative process of continuous developing exotic varieties with numerous variables.
... According to structure divergence at the I domain, the MIKC-type genes are classified into two subtypes, MIKC C and MIKC* [10,11]. The majority of functionally known MADS-box genes are MIKC C -type genes [12]. ...
MIKCC-type MADS-box genes are involved in floral organ identity determination but remain less studied in the Malus lineage. Based on the conserved domains of this gene family, we identified 341 genes among 13 species. Classification results showed that the MIKCC-type were generated later than the M-type, after the formation of Chlamydomonas reinhardtii. By phylogenetic analysis, three different groups were divided among 12 plant species, and one group was an ancestral MIKCC-type MADS-box homologous gene cluster from lower moss to higher flowering plants. Comparative analysis of these genes in A. thaliana and Malus lineages revealed a similar pattern evolutionary relationship with the phylogenetic analysis. Three classes of genes of the ABC model in A. thaliana had orthologous genes in the Malus species, but they experienced different evolutionary events. Only a whole-genome duplication (WGD) event was considered to act on the expansion of ABC-model-related genes in the Malus lineage. Additionally, the expression pattern of genes showed to be involved in flowering development stages and anther development processes among different M. domestica cultivars. This study systematically traced the evolutionary history and expansion mechanism of the MIKCC-type MADS-box gene family in plants. The results also provided novel insights for ABC model research of flower development in the Malus lineage.
... The bilaterally symmetric orchid flowers exhibit an extraordinary differentiation of morphology and adaptations [32,33]. Despite their great morphological diversity, the orchid flowers share a typical structure composed of three outer tepals, two laterals inner tepals, and a highly diversified median inner tepal (lip or labellum) [34]. ...
... As in all flowering plants, the genetic program at the basis of flower organ formation in orchids is realized mainly through the action of different MADS-box transcription factors [32,[35][36][37][38][39][40][41][42][43]. In addition to this program, known as the ABCE model, an orchidspecific regulatory network involving the class B MADS-box genes DEFICIENS-like (DEFlike) and AGAMOUS-LIKE 6 (AGL6) explains lip formation and symmetry determination [32,35,44]. ...
... As in all flowering plants, the genetic program at the basis of flower organ formation in orchids is realized mainly through the action of different MADS-box transcription factors [32,[35][36][37][38][39][40][41][42][43]. In addition to this program, known as the ABCE model, an orchidspecific regulatory network involving the class B MADS-box genes DEFICIENS-like (DEFlike) and AGAMOUS-LIKE 6 (AGL6) explains lip formation and symmetry determination [32,35,44]. ...
Plant transcription factors are involved in different developmental pathways. NAC transcription factors (No Apical Meristem, Arabidopsis thaliana Activating Factor, Cup-shaped Cotyledon) act in various processes, e.g., plant organ formation, response to stress, and defense mechanisms. In Antirrhinum majus, the NAC transcription factor CUPULIFORMIS (CUP) plays a role in determining organ boundaries and lip formation, and the CUP homologs of Arabidopsis and Petunia are involved in flower organ formation. Orchidaceae is one of the most species-rich families of angiosperms, known for its extraordinary diversification of flower morphology. We conducted a transcriptome and genome-wide analysis of orchid NACs, focusing on the No Apical Meristem (NAM) subfamily and CUP genes. To check whether the CUP homologs could be involved in the perianth formation of orchids, we performed an expression analysis on the flower organs of the orchid Phalaenopsis aphrodite at different developmental stages. The expression patterns of the CUP genes of P. aphrodite suggest their possible role in flower development and symmetry establishment. In addition, as observed in other species, the orchid CUP1 and CUP2 genes seem to be regulated by the microRNA, miR164. Our results represent a preliminary study of NAC transcription factors in orchids to understand the role of these genes during orchid flower formation.
... Aceto and Gaudio (2011) developed a special developmental-genetic code known as the"orchid code." This hypothesis proposed that the diversity of the orchid perianth was caused by duplication events and modifications in the regulatory areas of the MADS-box genes, followed by sub-and neo-functionalization (Aceto and Gaudio, 2011). Similarly, the orchid perianth (P)-code model indicates that the higher-order sepal/petal complex determines sepal and petal formation, whereas the lip complex is exclusively required for lip formation (Hsu et al., 2015). ...
It is beneficial for breeding and boosting the flower value of ornamental plants such as orchids, which can take several years of growth before blooming. Over the past few years, in vitro flowering of Cymbidium nanulum Y. S. Wu et S. C. Chen has been successfully induced; nevertheless, the production of many abnormal flowers has considerably limited the efficiency of this technique. We carried out transcriptomic analysis between normal and abnormal in vitro flowers, each with four organs, to investigate key genes and differentially expressed genes (DEGs) and to gain a comprehensive perspective on the formation of abnormal flowers. Thirty-six DEGs significantly enriched in plant hormone signal transduction, and photosynthesis-antenna proteins pathways were identified as key genes. Their broad upregulation and several altered transcription factors (TFs), including 11 MADS-box genes, may contribute to the deformity of in vitro flowers. By the use of weighted geneco−expression network analysis (WGCNA), three hub genes, including one unknown gene, mitochondrial calcium uniporter (MCU) and harpin-induced gene 1/nonrace-specific disease resistance gene 1 (NDR1/HIN1-Like) were identified that might play important roles in floral organ formation. The data presented in our study may serve as a comprehensive resource for understanding the regulatory mechanisms underlying flower and floral organ formation of C. nanulum Y. S. Wu et S. C. Chen in vitro.
