Bougainvillea spp., a tropical and subtropical woody plant of the family Nyctaginaceae, is highly valued for its ornamental traits, particularly its vibrant and diverse bracts. Despite its widespread horticultural applications, the molecular mechanisms governing bract development, flower color variation, and other floral traits remain largely unresolved. Recent advances in genome sequencing and multi-omics technologies have significantly advanced biological research on Bougainvillea. This review provides a systematic summary of recent progress, focusing on three aspects: (1) the hormonal regulatory network involved in bract development, including gibberellin and cytokinin signaling pathways and their interactions with key genes such as YABBY, KNOX, and ARP; (2) the formation of floral color, emphasizing the independent roles of betalain and flavonoid metabolic pathways and their interactions through substrate competition and transcriptional regulation; and (3) floral trait variation, integrating classical physiological and biochemical studies to highlight the functional diversification of MADS-box genes in the development of double-flowered forms. Collectively, this review establishes a comprehensive framework from phenotype to molecular mechanisms, providing a theoretical foundation for the molecular breeding and genetic improvement of Bougainvillea.
Three taxa of R. rugosa (Chinese Group), three taxa of R. centifolia, and one R. × damascena (Worldwide Group) were used to detect their volatile organic compound (VOC) contents using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. A total of 146 VOCs were detected, including 73 terpenoids, 18 phenylpropanoids/benzenoids, 50 fatty acid derivatives, and 5 other compounds. The contents of terpenoids were increasing with flower development, while the contents of fatty acid derivatives were decreasing. Heatmap cluster analysis (HCA) and Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) revealed that seven roses can be divided into Chinese and Worldwide groups, and α-farnesene, 9-nonadecene, 3-methyl-2-(2-methyl-2-butenyl)-furan, heptadecane, methyleugenol, β-myrcene, α-pinene, propanoic acid, 2-methyl-,1-(1,1-dimethylethyl)-2-methyl-1,3-propanediyl ester, pentadecane, and 2,2,4-Trimethyl-1,3-pentanediol diisobutyrate were the marker compounds for two groups. Sensory and incense tone compound evaluation showed that the aromas were mainly composed of floral, rosy, and sweet notes. However, the aroma of seven roses had a stronger spicy, woody, and citrus note in buds (S3) or full-blooming flower stages (S5), which were mainly caused by high contents of methyleugenol, β-myrcene, and β-pinene. In this study, the VOC profile and aromatic characteristics of oil-bearing roses were systematically compared between Chinese and Worldwide genotypes using metabolic pathway analysis and aroma evaluation, providing a more comprehensive reference for fragrant rose breeding.
Paeonia section Moutan DC is a group of economically significant plants in China, valued for their ornamental, medicinal, and industrial uses. As molecular studies on tree peony advance rapidly, identifying suitable reference genes for normalization of its real-time quantitative polymerase chain reaction (qRT-PCR) data has become increasingly important. In this study, petals collected at full bloom from 21 early-flowering and 21 late-flowering tree peony cultivars, as well as petals sampled across floral bud differentiation and flower development stages from the early-flowering cultivar Paeonia ostii "FengDan" and the late-flowering cultivar Paeonia suffruticosa "Lianhe", were used to systematically evaluate the stability of reference genes. The expression stability of 23 candidate reference genes was assessed using geNorm, NormFinder, BestKeeper, and RefFinder algorithms. Among these candidates, PPC was identified as the most suitable reference gene for both early- and late-flowering cultivars at the full-bloom stage. During floral bud differentiation and flower development, GTP exhibited high expression stability and was therefore deemed appropriate as a reference gene. The expression levels of all candidate genes were calibrated and normalized, providing a robust foundation for the accurate quantification of gene expression associated with flowering-time regulation in tree peony.
True blue flower coloration remains a rare and highly coveted trait in ornamental horticulture. Its natural occurrence is less than 10% of angiosperm species. The delphinidin derivatives provide the chromophoric basis for blue coloration; however, their structural stability is governed by intricate intramolecular and intermolecular interactions. To preserve blue hues, plants have evolved sophisticated stabilization mechanisms, including the formation of polyacylation, copigmentation, and metalloanthocyanin, as observed in Gentiana, Lamiaceae, and Delphinium. In this review, we integrate the current knowledge of biochemical mechanisms underlying natural blue pigments and evaluate the genetic engineering strategies aimed at creating blue flowers. These efforts to create blue flowers can be classified into three paradigms: (1) First-generation substrate engineering focused on introducing flavonoid 3',5'-hydroxylase (F3'5'H), which often yielded violet rather than true blue phenotypes due to vacuolar instability; (2) second-generation stabilization engineering incorporated endogenous copigments and successfully achieved stable blue coloration, as demonstrated in chrysanthemum; and (3) the emerging third-generation strategy seeks the autonomous reconstruction of complete stabilization modules. We highlight recent advances in synthetic biology that underpin this transition, including mitochondrial pH regulation via PhDC, manipulation of metal ion homeostasis, and the de novo assembly of polyacylation complexes, such as the Cineraria module. Together, these developments mark a shift from single-gene introduction toward rational metabolic design, providing a promising roadmap for overcoming evolutionary constraints in traditionally nonblue crops, such as roses and orchids.
Chinese orchids (Cymbidium spp.) are high-value ornamental plants, renowned for their elegant flowers, leaf variegation, and distinctive fragrance. However, their low transformation efficiency and prolonged regeneration periods have hindered the functional characterization of key genes in Cymbidium. To address these challenges, we developed a Tobacco rattle virus (TRV)-mediated virus-induced gene silencing (VIGS) system and a highly efficient Agrobacterium-mediated transient expression system using the Ruby reporter. These systems facilitate efficient transient gene silencing and overexpression in Cymbidium, enabling functional characterization of target genes. Phytoene desaturase (PDS), a visual marker commonly used for VIGS, and the Ruby reporter were selected to validate the system's efficiency. Infiltration with pTRV2-GFP confirmed that TRV can establish systemic infection and movement within Cymbidium plants. Furthermore, inoculation with pTRV2-CsPDS induced distinct photobleaching in leaves, and quantitative real-time polymerase chain reaction analysis confirmed the successful silencing of the endogenous PDS gene. We further optimized the VIGS conditions and identified the optimal parameters as an optical density at 600 nm (OD600) of 1.0 under a negative pressure of 0.06 MPa, followed by dark incubation at 25 degrees C for 24 h, which yielded the highest infiltration efficiency and plant survival rate. Using the Ruby reporter system, we also demonstrated efficient transient overexpression in Cymbidium petals and fleshy rhizomes. Additionally, we established that the optimal infiltration conditions for rhizomes were an Agrobacterium density of OD600 = 0.6 and a 10-min infiltration period. Collectively, the TRV-based VIGS system and the Ruby-based transient expression system offer reliable tools for comparative functional studies, enabling the dissection of molecular mechanisms that underlie key biological processes in Cymbidium.
Rosa is considered one of the most challenging and difficult groups in taxonomy and phylogenetics due to its wide distribution, extensive variability, and high hybridization potential, which leads to unclear interspecific boundaries. This paper summarizes and analyzes the progress in the distribution, survey, and classification of Rosa resources in China, based on years of research on the genus and a review of relevant literature. The latest distribution data for Rosa in China was updated, highlighting two key diversity centers where species richness is highest—regions with favorable hydrothermal conditions, minimal seasonal climatic variation, and high habitat heterogeneity. Additionally, 22 previously unpublished Rosa taxa (19 varieties and three forms) and 17 significant cultivars have been introduced. A new identification key for the genus Rosa in China has also been given. We also address issues in the classification of Rosa, offering fresh perspectives on interspecific boundaries, classification methods, and key taxonomic groups. This provides theoretical support for the identification, classification, and evolutionary research of Rosa species, and offers valuable references for the conservation and utilization of Rosa resources.
Plants of the order Nymphaeales are representative tropical and subtropical ornamental aquatic species, valued for their diverse flower colors, distinctive floral scents, and strong environmental adaptability. Although extensive studies have reported their chemical constituents, the roles of secondary metabolites in shaping ornamental traits remain insufficiently integrated. In this review, relevant literature published up to September 2025 was systematically retrieved from PubMed and Web of Science, and the major classes of secondary metabolites reported in representative genera (Nymphaea, Brasenia, and Nuphar) were summarized, with particular emphasis on their contributions to flower color and scent formation. Distinct chemotaxonomic patterns were identified: Nymphaea and Brasenia are predominantly enriched in flavonoids, polyphenols, and polysaccharides, whereas Nuphar is characterized by unique sulfur-containing sesquiterpene alkaloids. Accumulating evidence indicates that differential accumulation of specific anthocyanin derivatives underlies flower color diversification, while the composition and relative abundance of volatile organic compounds (VOCs) determine floral scent profiles among species and cultivars. These metabolite-based insights provide valuable targets for ornamental trait improvement, including flower color modification and fragrance-oriented breeding. In addition, the bioactive metabolites enriched in Nymphaeales support their further development as functional ornamental plants and value-added horticultural resources. This review highlights the integrative potential of linking metabolite diversity with ornamental trait formation to advance the sustainable utilization of tropical ornamental aquatic plants.
Melastoma species, widely distributed across tropical and subtropical areas, exhibit remarkable morphological diversity and environmental adaptability, with significant horticultural, ecological, and medicinal value in China. Recent genomic and multi-omics advances have made an initial contribution to the molecular bases of key traits, including hetero-morphic stamen regulation, aluminum hyper-accumulation, stress tolerance, and growth habit determination. The application of chromosome-level reference genomes, integrated with metabolomic and transcriptomic, have provided candidate genes and regulatory networks underpinning these traits. However, challenges remain, including limited sequenced species, insufficient functional validation, and the absence of robust breeding systems. Future efforts can focus on pan-genome construction, multi-omics integration, and functional studies to enable targeted molecular breeding, elite germplasm improvement, and sustainable utilization. These advances will facilitate the rational exploitation of Melastoma species for horticultural, medicinal, and ecological applications.
Madagascar periwinkle (Catharanthus roseus [L.] G. Don) is a valuable medicinal and ornamental plant, prized for its diverse alkaloid compounds and aesthetic traits. While extensively studied for pharmaceutical applications, its current understanding of preliminary genetic inheritance of ornamental traits and ornamental breeding research are less advanced compared to other horticultural crops. This review systematically examines the germplasm resources, genetic diversity, and breeding advancements in ornamental periwinkle, covering the utilization of wild and cultivated varieties, mutation and polyploidy breeding, and recent genomic sequencing efforts. The potentially genetic mechanisms underlying key ornamental characteristics such as flower color, flower type, and plant architecture are discussed, and emerging approaches evaluated, including marker-assisted selection, interspecific hybridization, and CRISPR-based editing integrated with multi-omics platforms, for trait decoding and precision breeding. Strategies are also highlighted to enhance resistance to prevalent diseases such as die-back and root rot. Finally, future research directions aimed at developing resilient, high-alkaloid cultivars suitable for sustainable ornamental horticulture are proposed. This work provides a comprehensive resource for accelerating molecular breeding and improving ornamental traits in C. roseus.
Rosa rugosa hips are a valuable resource rich in flavonoids with significant health benefits, though the regulatory mechanisms underlying flavonoid biosynthesis remain unclear. In R. rugosa hip, the chlorophyll content decreased significantly during hip ripening from the green (F0) to the yellow (F1) and red (F2) stages. In contrast, total flavonoid content peaked at the F1 stage, while anthocyanin and carotenoid levels showed a concomitant increase. To investigate the regulatory mechanisms, we performed integrated transcriptomic and metabolomic analyses of wild R. rugosa hips at the F1 and F2 stages. Transcriptomic data revealed 4,329 DEGs, which were predominantly enriched in 'Metabolic pathways' and 'Biosynthesis of secondary metabolites' by KEGG pathway enrichment analysis. Notably, 62 upregulated DEGs were assigned to specific flavonoid-related biosynthesis pathways. Meanwhile, metabolomic profiling identified 729 flavonoids, 308 of which were differentially accumulated metabolites (DAMs). Importantly, anthocyanin content increased upon ripening, while most other flavonoids decreased. Association analysis highlighted critical genes in anthocyanin biosynthesis, including upregulated BZ1, AOMT, 3MaT1, and 3MaT2, which correlated with the accumulation of specific derivatives like cyanidin 3-0-(6-027 malonyl)-beta-D-glucoside and peonidin 3-glucoside, contributing to the hip's red color. Similarly, CYP81E genes were linked to isoflavonoid accumulation, while downregulated CYP75B1 genes corresponded to decreased quercetin levels. These findings systematically elucidate the transcriptional and metabolic landscape of flavonoid biosynthesis during R. rugosa hip ripening, providing crucial insights for future genetic engineering aimed at enhancing flavonoid content and hip quality.
Low temperature is a key environmental cue governing floral transition and inflorescence development in nobile-type Dendrobium, and chilling treatments are routinely applied in horticultural practice to manipulate flowering time. Nevertheless, a robust genetic strategy for modulating flowering independent of temperature signals has yet to be established in this genus. To elucidate the molecular framework through which plants perceive and respond to chilling, we integrated cytological analyses with RNA sequencing (RNA-seq) to characterize transcriptional dynamics and chilling-responsive pathways under different low-temperature regimes. Continuous exposure to chilling markedly hastened floral induction, advancing flowering by nearly 1 month relative to plants maintained under standard growth conditions. Comparative transcriptomic analysis identified 13,708 differentially expressed genes (DEGs) between chilled and control plants. KEGG enrichment revealed strong overrepresentation of pathways related to photosynthesis and plant hormone signal transduction. Further analyses indicated that chilling triggered extensive reprogramming of hormone-related, cold-responsive, and floral-developmental genes. Specifically, low temperature reshaped hormonal homeostasis by elevating transcripts associated with CK and ABA catabolism, stimulating GA biosynthetic enzymes, and repressing JA biosynthesis. Concurrently, chilling suppressed FRI expression, while activating key cold-responsive genes, floral integrators, and meristem identity regulators, including LEA, FT, LFY,AP1, and CAL, collectively accelerated floral transition and organ initiation. These results not only offered actionable insights for horticultural control of flowering time, but also provided a valuable genetic resource for understanding chilling-induced flowering in nobile-type Dendrobium.
Flower color is a key trait determining the commercial value of ornamental plants. As changes in flower color are increasingly appealing to home gardening consumers, they have become a key trendsetter for future breeding. However, the molecular mechanism underlying flower color change during the postflowering stage in flowers remains unclear. In this study, the chrysanthemum cultivar 'f23' (exhibiting deepening flower color with flower aging) was used to explore post-flowering flower color change via an integrated approach of HPLC and transcriptomic analyses. HPLC results showed that two cyanidin glycosides accumulated significantly in ray florets during the post-flowering stage, whereas the total flavonoid content decreased. Transcriptomic analysis revealed that differentially expressed genes were mainly enriched in flavonoid biosynthesis and plant hormone signal transduction pathways. Notably, the ABA signal transduction gene CmSnRK2.6 was identified as a hub gene regulating anthocyanin biosynthesis during the post-flowering stage. Overexpression of CmSnRK2.6 in tobacco resulted in deepened flower color and increased anthocyanin accumulation, accompanied by significant upregulation of core anthocyanin biosynthetic genes. Yeast two-hybrid (Y2H) assays verified a direct physical interaction between CmSnRK2.6 and CmbHLH2.1. Yeast one-hybrid (Y1H) and dual-luciferase assays further confirmed that CmbHLH2.1 directly binds to the promoter of CmDFR and activates its transcription. This study provides a theoretical basis and abundant genetic resources for molecular breeding aimed at flower color improvement in chrysanthemums.
Fragrance is an important ornamental trait in Clematis (Ranunculaceae), yet rapid and standardized evaluation methods are still lacking. In this study, we established an electronic nose (E-nose)-based protocol for efficient fragrance detection in Clematis and characterized the volatile response profiles across diverse germplasm. Using an orthogonal experimental design, we optimized E-nose operating conditions by analysis of variance (ANOVA) and multiple comparisons. Three factors significantly affected sensor responses: flowering stage, headspace equilibration time, and sample temperature. The optimal detection combination was A(3)B(1)C(3), i.e., sampling at the late full flowering stage, and equilibrating for 6 h at 20 degrees C. Among the sensors, W2W, W1W, and W1S showed significantly higher response values than the others (p < 0.05). It indicated that Clematis floral scent is likely dominated by aromatic sulfides, alkanes, and other S-containing compounds. We then applied the optimized system to 97 Clematis germplasm resources from 11 horticultural groups. They were classified into three E-nose fragrance types: (1) high-response/complex type; (2) medium-response/balanced type; and (3) low-response/simple type. Finally, 15 germplasm resources with outstanding fragrance performance were identified. This work establishes a rapid, reproducible, E-nose detection system for Clematis floral scent and provides a practical tool for early selection of fragrant parents in breeding. The fragrance fingerprints generated here further suggest that sulfides and alkanes are key discriminating volatiles in Clematis based on sensor characteristics, supporting both cultivar classification and aroma-oriented breeding.
Anthocyanins are vital secondary metabolites in plants, playing key roles in defending against diverse biotic and abiotic stresses. WRKY transcription factors are known to participate in stress-induced anthocyanin accumulation; however, the mechanism by which WRKY transcription factors regulate anthocyanin biosynthesis in rose (Rosa chinensis) remains unreported. In this study, we identified RcWRKY71, a Group IIc WRKY transcription factor containing the conserved WRKYGQK heptapeptide and a C2H2-type zinc finger motif.Subcellular localization analysis revealed that RcWRKY71 is localized in the nucleus and possesses transcriptional activation activity. Functional characterization demonstrated that RcWRKY71 promotes anthocyanin accumulation in rose petals and enhances drought tolerance. Further mechanistic studies showed that RcWRKY71 activates anthocyanin biosynthesis by directly binding to the promoters of three R2R3-MYB transcription factors: RcMYB1, RcMYB113c, and RcMYB114a. Additionally, RcWRKY71 forms homodimers via its leucine (Leu) zipper domain, which is essential for its functional enhancement. Our findings reveal a novel regulatory mechanism by which WRKY transcription factors modulate anthocyanin accumulation and confer drought resistance in rose, highlighting the role of Leu zipper-mediated homodimerization in enhancing transcriptional activity.
Plant height is a critical trait for ornamental plants, directly affecting their aesthetic value and commercial applications. Viola tricolor exhibits a compact growth habit due to its shortened internodes, which grant it significant advantages in landscaping. However, the molecular mechanisms regulating internode elongation in this species remain unclear. This study conducted a comparative transcriptomic analysis of the long-internode inbred line (08H) and the short-internode inbred line (JP) of V. tricolor before and after jointing. The results revealed significant differences in gibberellin (GA) signaling pathways, with exogenous GA3 application promoting internode elongation, particularly in JP. Among the differentially expressed genes, the DELLA family transcription factor VtRGL1 (Vtr06G053680) was identified as a key candidate. Subcellular localization confirmed its nuclear and cytoplasmic distribution, and overexpression of VtRGL1 in Arabidopsis thaliana resulted in delayed bolting and reduced plant height, consistent with its inhibitory effect on GAmediated growth. Co-expression network analysis further supports its regulatory function in the GA signaling pathway. These findings provide new insights into the genetic regulation of plant morphology in V. tricolor, and offer a promising target for molecular breeding of compact ornamental varieties.
The MYB proteins represent one of the most prevalent transcription factors in plants that play critical roles in various biological processes. The Cymbidium species occupy a dominant role in global floriculture markets due to their high ornamental value. In this study, a genome-wide identification and characterization of MYB proteins in C. sinense, C. haematode, and other closely related Cymbidium species were performed. A total of 170 MYB proteins (CysMYBs) were identified in C. sinense. Phylogenetic analysis classified these CysMYBs into 33 subfamilies, with 23 members from S4, S5, S6, S7, and S9 subfamilies that are potentially involved in anthocyanin regulation. Chromosomal distribution revealed uneven gene clustering, and 23 pairs of syntenic relationships, indicating gene expansion through fragment or tandem duplication events. Transcriptome and qRT-PCR analyses demonstrated functional divergence and species-specific regulation of anthocyanin synthesis in C. sinense, and its close relative C. haematodes. In particular, CysMYB72 and CysMYB114 exhibited species-specific roles in anthocyanin synthesis in C. sinense flowers, whereas CysMYB131 and CysMYB88 were proposed as key regulators of anthocyanin accumulation in C. haematodes. Cyanidin derivatives were identified as the primary anthocyanins in floral tissues, with the abundance correlating with CysMYB expression patterns. In conclusion, this study elucidates the functional divergence of MYB transcription factors in orchids and provides foundational insights into the molecular mechanisms underlying anthocyanin biosynthesis in Orchidaceae species.
Continuous cropping obstacle (CCO) severely limits the sustainable production of high-value cut flowers like lisianthus (Eustoma grandiflorum), primarily driven by species-specific negative plant-soil feedback (PSF). Although autotoxic compounds are implicated, the mechanisms behind this specificity remain elusive. This study investigated the role of extracellular self-DNA (sDNA) as a species-specific autotoxic stress in mediating negative PSF under a prolonged exposure scenario. This study first demonstrated that the growth-inhibitory effect of fragmented extracellular DNA is phylogenetically dependent, with conspecific DNA causing the strongest suppression, followed by DNA from closely related Gentiana species. Chronic exposure to lisianthus sDNA induced a concentration-dependent ecotoxic response, including significant reactive oxygen species (ROS) accumulation, disruption of root cellular architecture, and overall growth inhibition, with a half-maximal effective concentration (EC50) of 51.0 mu g/mL (R2 = 0.816). Transcriptomic profiling further indicated that longterm sDNA exposure activated defense pathways akin to pathogen-associated molecular pattern (PAMP) responses (e.g., 'response to chitin', 'response to fungus', and 'defense response to fungus'), while concurrently repressing genes involved in primary metabolism. To investigate the paradox of sDNA acting as both a defense elicitor and a growth suppressor, a pathogen challenge assay was conducted. Pretreatment with sDNA for 24 h significantly enhanced the susceptibility of lisianthus to the soil-borne pathogen Fusarium oxysporum, suggesting that the sDNA-induced physiological damage may outweigh its potential defensive benefits. The present findings propose that sDNA drives negative PSF through a self-reinforcing cycle, in which monoculture-induced sDNA accumulation directly impairs root health and plant vigor, which in turn predisposes the plant to pathogen infection, further exacerbating root decay and sDNA release. This mechanistic cycle highlights a key pathway underpinning the persistent soil sickness in the continuous cropping system of lisianthus.
This study established a market-oriented evaluation framework for selecting elite cut peony (Paeonia lactiflora) cultivars by integrating 15 key traits across five dimensions: ornamental quality, stem commercial traits, yield potential, vase performance, and management ease. Using the Analytic Hierarchy Process (AHP), the most influential criteria were identified as ornamental quality (31.90%), stem commercial traits (25.95%), and vase performance (18.31%). Consumer preference analysis, based on K-means clustering, revealed that pink-white and soft pink colors, as well as semi-double flower types, were the most favored by consumers. Traditional grading standards for vase life failed to distinguish between cultivars; therefore vase life was reclassified using K-means clustering, and the opening rate was incorporated to enhance accuracy. The integrated AHP-K-means approach classified 78 cultivars into three performance levels, and identified 25 elite varieties with superior floral traits, upright stems, and extended vase life. This framework effectively links consumer preference with quantitative trait evaluation, and provides a practical tool for breeding and selecting high-quality cut peony cultivars.
