Search Results (29)

Grindelia mutabilis (Asteraceae, Astereae), a new species from Brazil endemic to the Espinal Ecoregion of the Río de La Plata Grasslands Bioregion and Pampa Province of the Chaco Biogeographical Domain, is proposed and illustrated. The new species is characterized by a combination of traits: small, rosette cespitose habit, linear to linear–oblanceolate leaves, light-yellow to pastel salmon ray florets, three-winged ray floret cypselae bearing a pappus of two to four elements and two-winged disc floret cypselae bearing a pappus of two elements. It has a highly restricted habitat and is known exclusively within Parque Estadual do Espinilho in Rio Grande do Sul, Brazil. Preliminary conservation assessments classify the new species as Critically Endangered. We provide illustrations and photographs, as well as a distribution map with an identification key for the South American Grindelia species with winged cypselae. The intriguing morphology of this species combines characters traditionally regarded as diagnostic for Notopappus, a genus segregated from Haplopappus and Grindelia. Previously published phylogenetic studies of related taxa indicate that the recognition of Notopappus as monophyletic is not supported and render Grindelia as non-monophyletic too. Based on this combined morphological evidence and existing phylogenetic hypotheses, we reaffirm the non-monophyly of Notopappus and formally propose its synonymization under Grindelia s.l. Full article

Anthocyanins, biosynthesized through the flavonoid pathway, critically determine floral coloration and ornamental value in plants. While floral development has been extensively studied in Gerbera hybrida, the microRNA-mediated regulation of anthocyanin biosynthesis remains unclear. In this study, we identified and characterized the precursor of gerbera microRNA156 (GhmiR156), which exhibits a typical stem-loop secondary structure. The mature GhmiR156 sequence shows 93.65% similarity with miR156 from other plants. Through target prediction analysis, we identified five potential target genes of GhmiR156, all encoding SQUAMOSA Promoter-Binding Protein-Like (SPL) transcription factors. Among these, the gene c35442.graph_c0, which shares the highest similarity with AtSPL2 in Arabidopsis, was designated as GhSPL2. Expression analysis revealed an inverse correlation between GhmiR156 and GhSPL2 across different tissues and developmental stages of ray florets. This regulatory relationship was further validated by RLM-5′RACE, which showed that GhmiR156 directly targets and cleaves GhSPL2 mRNA, subsequently supported by dual-luciferase reporter assays and Western blotting analysis. Subcellular localization analysis indicated that GhSPL2 is a nuclear-localized protein, consistent with AtSPL2. Functional analyses revealed that overexpression of GhSPL2 suppressed anthocyanin accumulation by downregulating key biosynthetic genes GhPAL, GhF3H and GhUFGT. Conversely, overexpression of GhmiR156 represses GhSPL2 expression, thereby alleviating its inhibitory effect on anthocyanin accumulation in ray florets, and exhibits an increase in anthocyanin content. Collectively, our findings demonstrate that GhmiR156 fine-tunes the anthocyanin biosynthetic pathway through its target gene GhSPL2. This study provides new insights into the complex regulatory network governing anthocyanin biosynthesis in ornamental plants. Full article

The APETALA2/Ethylene-Responsive Factor (AP2/ERF) superfamily is one of the largest transcription factor families in plants, playing diverse roles in development, stress response, and metabolic regulation. Despite their ecological and economic importance, AP2/ERF genes remain uncharacterized in marigold (Tagetes erecta), a valuable ornamental and medicinal plant in the Asteraceae family known for its unique capitulum-type inflorescence with distinct ray and disc florets. Here, we conducted a comprehensive genome-wide analysis of the AP2/ERF superfamily in marigold and identified 177 AP2/ERF genes distributed across 11 of the 12 chromosomes. Phylogenetic analysis revealed their classification into the AP2 (28 genes), ERF (143 genes), RAV (4 genes), and Soloist (2 genes) families based on domain architecture. Gene structure and motif composition analyses demonstrated group-specific patterns that correlated with their evolutionary relationships. Chromosome mapping and synteny analyses revealed that segmental duplications significantly contributed to AP2/ERF superfamily gene expansion in marigold, with extensive collinearity observed between marigold and other species. Expression profiling across different tissues and developmental stages indicated distinct spatio-temporal expression patterns, with several genes exhibiting tissue-specific expression in Asteraceae-specific structures. In floral organs, TeAP2/ERF145 exhibited significantly higher expression in ray floret corollas compared to disc florets, while TeAP2/ERF103 showed stamen-specific expression in disc florets. Protein interaction network analysis revealed AP2 as a central hub with extensive predicted interactions with MADS-box and TCP family proteins. These findings suggest that AP2 family genes may collaborate with MADS-box and CYC2 genes in regulating the characteristic floral architecture of marigold, establishing a foundation for future functional studies and molecular breeding efforts to enhance ornamental and agricultural traits in this economically important plant. Full article

Background: The attractive inflorescence of Chrysanthemum morifolium, its capitulum, is always composed of ray (female, zygomorphy) and disc (bisexual, actinomorphy) florets, but the formation mechanism remains elusive. The gene diversification pattern of the ECE (CYC/TB1) clade has been speculated to correlate with the capitulum. Within the three subclades of ECE, the involvement of CYC2 in defining floret identity and regulating flower symmetry has been demonstrated in many species of Asteraceae, including C. morifolium. Differential expression of the other two subclade genes, CYC1 and CYC3, in different florets has been reported in other Asteraceae groups, yet their functions in flower development have not been investigated. Methods: Here, a CYC1 gene, CmCYC1a, was isolated and its expression pattern was studied in C. morifolium. The function of CmCYC1a was identified with gene transformation in Arabidopsis thaliana and yeast two-hybrid (Y2H) assays were performed to explore the interaction between CmCYC1 and CmCYC2. Results: CmCYC1a was expressed at higher levels in disc florets than in ray florets and the expression of CmCYC1a was increased in both florets during the flowering process. Overexpression of CmCYC1a in A. thaliana changed flower symmetry from actinomorphic to zygomorphic, with fewer stamens. Furthermore, CmCYC1a could interact with CmCYC2b, CmCYC2d, and CmCYC2f in Y2H assays. Conclusions: The results provide evidence for the involvement of CmCYC1a in regulating flower symmetry and stamen development in C. morifolium and deepen our comprehension of the contributions of ECE genes in capitulum formation. Full article

Marigold (Tagetes erecta) has a capitulum with two floret types: sterile ray florets and fertile disc florets. This distinction makes marigold a valuable model for studying floral organ development in Asteraceae, where MADS-box transcription factors play crucial roles. Here, 65 MADS-box genes were identified in the marigold genome, distributed across all 12 chromosomes. These genes were classified into type I (13 genes) and type II (52 genes) according to phylogenetic relationships. The gene structure of type I was simpler than that of type II, with fewer conserved motifs. Type I was further divided into three subclasses, Mα (8 genes), Mβ (2 genes), and Mγ (3 genes), while type II was divided into two groups: MIKC^C (50 genes) and MIKC* (2 genes), with MIKC^C comprising 13 subfamilies. Many type II MADS-box genes had evolutionarily conserved functions in marigold. Expression analysis of type II genes across different organs revealed organ-specific patterns, identifying 34 genes related to flower organ development. Given the distinct characteristics of the two floret types, four genes were specifically expressed only in the petals of one floret type, while twenty genes were expressed in the stamens of disc florets. These genes might have been related to the formation of different floret types. Our research provided a comprehensive and systematic analysis of the marigold MADS-box genes and laid the foundation for further studies on the roles of MADS-box genes in floral organ development in Asteraceae. Full article

The diversity in the petal morphology of chrysanthemums makes this species an excellent model for investigating the regulation mechanisms of petal size. However, our understanding of the molecular regulation of petal growth in chrysanthemums remains limited. The GASA (gibberellic acid [GA]-stimulated Arabidopsis) protein plays a significant role in various aspects of plant growth and development. Previous studies have indicated that GEG (a gerbera homolog of the gibberellin-stimulated transcript 1 [GAST1] from tomato) is involved in regulating ray petal growth by inhibiting cell expansion in gerberas. In this study, we successfully cloned the GASA family gene from chrysanthemums, naming it CmGEG, which shares 81.4% homology with GEG. Our spatiotemporal expression analysis revealed that CmGEG is expressed in all tissues, with the highest expression levels observed in the ray florets, particularly during the later stages of development. Through transformation experiments, we demonstrated that CmGEG inhibits petal elongation in chrysanthemums. Further observations indicated that CmGEG restricts cell elongation in the top, middle, and basal regions of the petals. To investigate the relationship between CmGEG and GA in petal growth, we conducted a hormone treatment assay using detached chrysanthemum petals. Our results showed that GA promotes petal elongation while downregulating CmGEG expression. In conclusion, the constrained growth of chrysanthemum petals may be attributed to the inhibition of cell elongation by CmGEG, a process regulated by GA. Full article

The cut chrysanthemum holds one of the most substantial segments of the global floriculture market, particularly in Korea. We conducted a detailed assessment of the genetic structures across the cut chrysanthemum breeding lines in Korea. Using standard and spray chrysanthemum breeding lines from leading Korean research institutes, we first compared the variability of 12 horticultural traits, revealing a wide range of variation for most traits. We found that the overall flower diameter (OFD) and ray floret length (RFL) showed a solid positive relationship, regardless of the type. From a multivariate approach, OFD, RFL, and ray floret width (RFW) show consistently high association. Genotypic and phenotypic coefficients of variation analyses further indicated the significant genetic control over most traits. However, certain traits, like the volume of flowers (VF) in standard types, are more influenced by environments. Lastly, our analysis demonstrated substantial variability in broad-sense heritability (H); plant height (PH) consistently showed high H in both types. But the number of side branches (NOSB) and VF exhibited inconsistent H scores. These findings highlight the need for type-specific breeding strategies and modulating environmental management to optimize the trait expressions depending on the H scores, which offers significant implications for future breeding strategies. Full article

Gerbera (Gerbera hybrida) is a widely cultivated ornamental plant. However, its genetic improvement is limited by the lack of genetic analysis and molecular markers for traits. In this study, we analyzed the phenotypic and genotypic variation of 140 F₁ progeny from two gerbera varieties with different flower types and colors. We evaluated the flower’s morphology, color, and pigment content of the F₁ population and performed cluster principal component analysis (PCA) and correlation analysis. The results showed that the main ornamental traits of the hybrid progeny varied greatly. The segregation ratios of single and double flowers and ligulate and split ray florets were both 1:1. The flower colors of the F₁ progeny were mainly red and purple-red, similar to the male parent’s color. Furthermore, we conducted a genetic analysis of the hybrid progeny using EST-SSR markers and performed association analysis with phenotypic traits. We identified 2, 2, 3, 1, and 2 loci to be associated with peduncle length (PL), ray floret length (RFL), and outer ray floret; the level of apex relative to the top of involucre (LAI); outer corolla lips (OCL); and the b* of ray floret color, respectively. Our results reveal the genetic patterns of important ornamental traits and provide a theoretical basis and practical tools for gerbera genetic breeding. Full article

The chrysanthemum is widely used as a cut flower, potted flower, and garden flower worldwide and has high ornamental, edible, and medicinal value. The flower heads, composed of ray florets and disc florets, are the most diverse in terms of morphology among ornamental plants. Here, we compared and analyzed the developmental processes of different capitulum types as well as ray florets and disc florets. Morphological differentiation of the two florets occurred on the dorsal domain of the petals at stage Ⅳ of flower development, and differences in stamen development occurred at stage Ⅴ. The dorsal domain of the ray florets and the early stage of flower development were also an essential site and period, respectively, for the differences among capitulum types. In situ hybridization revealed that CmCYC2c, whose homologs are involved in the specification of floret identity in Asteraceae, was expressed in both the dorsal and ventral domains of the ray petals in the tubular-type chrysanthemum, whereas, it was differentially transcribed in the ray petals of flat- and spoon-type chrysanthemum cultivars and had lower or no expression in the dorsal domain and higher expression in the ventral domain at stage Ⅳ. Our study indicates that the expression pattern of CmCYC2c on the dorsal domain of the ray floret at stage Ⅳ contributes to the formation of diverse flower head types in chrysanthemums. Full article

Aromatic and medicinal plants are a great source of useful bioactive compounds for use in cosmetics, drugs, and dietary supplements. This study investigated the potential of using supercritical fluid extracts obtained from Matricaria chamomilla white ray florets, a kind of industrial herbal byproduct, as a source of bioactive cosmetic ingredients. Response surface methodology to optimize the supercritical fluid extraction process by analyzing the impact of pressure and temperature on yield and the main bioactive compound groups were used. High-throughput 96-well plate spectrophotometric methods were used to analyze the extracts for total phenols, flavonoids, tannins, and sugars, as well as their antioxidant capacity. Gas chromatography and liquid chromatography–mass spectrometry was used to determine the phytochemical composition of the extracts. The extracts were also analyzed for antimicrobial activity, cytotoxicity, phototoxicity, and melanin content. Statistical analysis was performed to establish correlations between the extracts and develop models to predict the targeted phytochemical recovery and chemical and biological activities. The results show that the extracts contained a diverse range of phytochemical classes and had cytotoxic, proliferation-reducing, and antimicrobial activities, making them potentially useful in cosmetic formulations. This study provides valuable insights for further research on the uses and mechanisms of action of these extracts. Full article

Opisthopappus is a perennial, endemic herb of the Taihang Mountains in China. Two species of this genus (O. longilobus and O. taihangensis) are important wild genetic resources for Asteraceae; however, their reproductive biology has been lacking until now. This study is the first detailed report on the reproductive biology and breeding systems of two Opisthopappus species. Through field observations, the floral syndromes of O. longilobus and O. taihangensis were found to possess a similar pattern, although O. taihangensis has a relatively larger capitulum, more ray ligules, and disc florets. The flowers of both O. longilobus and O. taihangensis are protandrous, a character that can prevent autogamy at the single-flower level, and insects are required for pollination. Further, brightly ligules, brightly bisexual florets, unique fragrance, and amount of nectar suggest that these species propagate via an entomophilous pollination system. Hymenopteran and Diptera species were observed as the effective pollinators for these two species. The outcrossing index, pollen/ovule ratio and the results of hand pollination indicated that these Opisthopappus species might have a mixed mating system that combines cross-fertilization and partial self-fertilization for O. longilobus and O. taihangensis, outcrossing predominated in the breeding system, while self-pollination played an important role in seed production when insect pollination was unavailable, particularly in a harsh environment, such as the Taihang Mountains cliffs. Meanwhile, O. taihangensis might better adapt to severe surroundings with relatively complex floral syndromes, specifically through the attraction of visiting insects and a high seed set rate. The above results not only provide reference information toward a better understanding of the survival strategies of O. longilobus and O. taihangensis in the Taihang Mountains but also lay a solid foundation for further exploring the molecular mechanisms that underly their adaptation under cliff environments. Full article

Chrysanthemum is a genus in the Asteraceae family containing numerous cut flower varieties with high ornamental value. It owes its beauty to the composite flower head, which resembles a compact inflorescence. This structure is also known as a capitulum, in which many ray and disc florets are densely packed. The ray florets are localized at the rim, are male sterile, and have large colorful petals. The centrally localized disc florets develop only a small petal tube but produce fertile stamens and a functional pistil. Nowadays, varieties with more ray florets are bred because of their high ornamental value, but, unfortunately, this is at the expense of their seed setting. In this study, we confirmed that the disc:ray floret ratio is highly correlated to seed set efficiency, and therefore, we further investigated the mechanisms that underlie the regulation of the disc:ray floret ratio. To this end, a comprehensive transcriptomics analysis was performed in two acquired mutants with a higher disc:ray floret ratio. Among the differentially regulated genes, various potential brassinosteroid (BR) signaling genes and HD-ZIP class IV homeodomain transcription factors stood out. Detailed follow-up functional studies confirmed that reduced BR levels and downregulation of HD-ZIP IV gene Chrysanthemum morifolium PROTODERMAL FACTOR 2 (CmPDF2) result in an increased disc:ray floret ratio, thereby providing ways to improve seed set in decorative chrysanthemum varieties in the future. Full article

The formation mechanism of different ray floret shapes of chrysanthemum (Chrysanthemum × morifolium) remains elusive due to its complex genetic background. C. vestitum, with the basic ray floret shapes of the flat, spoon, and tubular types, is considered a model material for studying ray floret morphogenesis. In this study, the flat and tubular type lines of C. vestitum at specific stages were used to investigate the key genes that regulate morphological differences in ray florets. We found that the expression levels of genes related to auxin synthesis, transport, and response were generally higher in the tubular type than in the flat type. CvARF3 was highly expressed in the flat type, while CvARF5 and CvARF6 were highly expressed in the tubular type. Additionally, the transcription levels of Class B and E genes closely related to petal development, including CvPI, CvAP3, Cvdefh21, CvSEP3, and CvCDM77, were expressed at higher levels in the tubular type than the flat type. Based on the results, it is proposed that auxin plays a key role in the development of ray florets, and auxin-related genes, especially CvARFs, may be key genes to control the morphological difference of ray florets. Simultaneously, MADS-box genes are involved in the co-regulation of ray floret morphogenesis. The results provide novel insights into the molecular mechanism of different petal type formation and lay a theoretical foundation for the directional breeding of petal type in chrysanthemums. Full article

The essential oil of German chamomile (Matricaria recutita L.) is widely used in food, cosmetics, and the pharmaceutical industry. α-Bisabolol is the main active substance in German chamomile. Farnesyl diphosphate synthase (FPS) and α-bisabolol synthase (BBS) are key enzymes related to the α-bisabolol biosynthesis pathway. However, little is known about the α-bisabolol biosynthesis pathway in German chamomile, especially the transcription factors (TFs) related to the regulation of α-bisabolol synthesis. In this study, we identified MrFPS and MrBBS and investigated their functions by prokaryotic expression and expression in hairy root cells of German chamomile. The results suggest that MrFPS is the key enzyme in the production of sesquiterpenoids, and MrBBS catalyzes the reaction that produces α-bisabolol. Subcellular localization analysis showed that both MrFPS and MrBBS proteins were located in the cytosol. The expression levels of both MrFPS and MrBBS were highest in the extension period of ray florets. Furthermore, we cloned and analyzed the promoters of MrFPS and MrBBS. A large number of cis-acting elements related to light responsiveness, hormone response elements, and cis-regulatory elements that serve as putative binding sites for specific TFs in response to various biotic and abiotic stresses were identified. We identified and studied TFs related to MrFPS and MrBBS, including WRKY, AP2, and MYB. Our findings reveal the biosynthesis and regulation of α-bisabolol in German chamomile and provide novel insights for the production of α-bisabolol using synthetic biology methods. Full article

In this research, we have reported the valorization possibilities of Matricaria recutita white ray florets using supercritical fluid extraction (SFE) with CO₂. Experiments were conducted at temperatures of 35–55 °C and separation pressures of 5–9 MPa to evaluate their impact on the chemical composition and biological activity of the extracts. The total obtained extraction yields varied from 9.76 to 18.21 g 100 g⁻¹ DW input. The greatest extraction yield obtained was at 9 MPa separation pressure and 55 °C in the separation tank. In all obtained extracts, the contents of total phenols, flavonoids, tannins, and sugars were determined. The influence of the supercritical CO₂ extraction conditions on the extract antioxidant capacity was evaluated using the quenching activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH). The chemical composition of the extracts was identified using both gas and liquid chromatography–mass spectrometry methods, whereas analyses of major and minor elements as well as heavy metals by microwave plasma atomic emission spectrometer were provided. Moreover, extracts were compared with respect to their antimicrobial activity, as well as the cytotoxicity and phototoxicity of the extracts. The results revealed a considerable diversity in the phytochemical classes among all extracts investigated in the present study and showed that the Matricaria recutita white ray floret by-product possesses cytotoxic and proliferation-reducing activity in immortalized cell lines, as well as antimicrobial activity. To the best of our knowledge, this is the first paper presenting such comprehensive data on the chemical profile, antioxidant properties, and biological properties of SFE derived from Matricaria recutita white ray florets. For the first time, these effects have been studied in processing by-products, and the results generated in this study provide valuable preconditions for further studies in specific test systems to fully elucidate the mechanisms of action and potential applications, such as potential use in cosmetic formulations. Full article