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Mature flowers and petals with pseudonectaries in four species of Eranthis. A–CEranthis stellata. D–FEranthis lobulata. G–IEranthis pinnatifida. J–LEranthis hyemalis. White arrows indicate pseudonectaries, and black arrows indicate nectaries located at the base of the nectary grooves. C, carpels; P, petals; S, sepals; St, stamens. Scale bars: A–B, D–E, G–H, J–K = 1 cm; C, F, I, L = 1 mm
Source publication
Flowers are an innovative characteristic of angiosperms, and elaborate petals usually have highly specialized structures to adapt to different living environments and pollinators. Petals of Eranthis have complex bilabiate structures with nectaries and pseudonectaries; however, the diversity of the petal micromorphology and structure is unknown. Pet...
Citations
... The petals in Ranunculales are complex in shape of lobes, protuberances, sacs, and spurs. The elaborate petals are usually associated with nectar tissue (Endress and Matthews 2006;Damerval and Nadot 2007), for example, petal sacs or spurs of Epimedium (Berberidaceae), Aquilegia, Delphinium, and Helleborus (Ranunculaceae) have the function as nectar productions and nectar holders (Vesprini et al. 1999;Kramer and Hodges 2010;Antoń and Kamińska 2015;Xie et al. 2022;Zhu et al. 2023); some petals have prominent pseudonectaries that function as visual attractants and nectar guides, such as Eranthis and Nigella (Ranunculaceae) (Liao et al. 2020;Huang and Zhang 2022). The petals in Papaveraceae can recognize as two types: flat petals (Papaveroideae) and elaborate petals with wings, crests, or spurs (Fumarioideae), and the outer petals may have the function as nectar holders, with the staminal nectaries located at the base of the filaments in Fumarioideae Wang et al. 2023). ...
Main conclusion
Petal developmental characteristics in Fumarioideae were similar at early stages, and the specialized nectar holder/pollen container formed by the outer/inner petals. The micro-morphology of these two structures, however, shows diversity in seven species.
Abstract
Elaborate petals have been modified to form different types, including petal lobes, ridges, protuberances, and spurs, each with specialized functions. Nectar holder and pollen container presumably have a function in plant–pollinator interactions. In Fumarioideae, four elaborate petals of the disymmetric/zygomorphic flower present architecture forming the “nectar holder” and “pollen container” structure at the bottom and top separately. In the present study, the petals of seven species in Fumarioideae were investigated by scanning electron microscopy, light microscope, and transmission electron microscopes. The results show that petal development could divided into six stages: initiation, enlargement, adaxial/abaxial differentiation, elaborate specializations (sacs, spurs, and lobes formed), extension, and maturation, while the specialized “nectar holder” and “pollen container” structures mainly formed in stage 4. “Nectar holder” is developed from the shallow sac/spur differentiated at the base of the outer petal, eventually forming a multi-organized complex structure, together with staminal nectaries (1–2) with individual sizes. A semi-closed ellipsoidal “pollen container” is developed from the apical part of the 3-lobed inner petals fused by middle lobes and attain different sizes. The adaxial epidermis cells are specialized, with more distinct punctate/dense columnar protrusions or wavy cuticles presented on obviously thickening cell walls. In addition, a large and well-developed cavity appears between the inner and outer epidermis of the petals. As an exception, Hypecoum erectum middle lobes present stamen mimicry. Elaborate petal structure is crucial for comprehending the petal diversity in Fumarioideae and provides more evidence for further exploration of the reproductive study in Papaveraceae.
... Eranthis sect. Shibateranthis has long-lived tubers, white sepals, and bilobate or forked petal margins with pseudonectaries [7,15]. Species of this section have a natural geographic range in temperate North and East Asia, i.e., Eranthis albiflora Franch., E. byunsanensis B.Y. Sun, E. lobulata W.T. Wang, E. pinnatifida Maxim., E. pungdoensis B.U. Oh, E. sibirica DC., E. stellata Maxim., and E. tanhoensis Erst [2,4,5]. ...
Comparative karyotype analysis of four out of the six species of yellow-flowered Eranthis sect. Eranthis, i.e., E. bulgarica, E. cilicica, E. hyemalis, and E. longistipitata from different areas, has been carried out for the first time. All the studied specimens had somatic chromosome number 2n = 16 with basic chromosome number x = 8. Karyotypes of all the investigated plants included five pairs of metacentric chromosomes and three pairs of submetacentric/subtelocentric chromosomes. The chromosome sets of the investigated species differ mainly in the ratio of submetacen-tric/subtelocentric chromosomes, their relative lengths and arm ratios. A new oligonucleotide probe developed and tested to detect 45S rDNA clusters. Using this probe and an oligonucleotide probe to 5S rDNA, 45S and 5S rDNA clusters were localized for the first time on chromosomes of E. cilicica, E. hyemalis, and E. longistipitata. Major 45S rDNA clusters were identified on satellite chromosomes in all the species; in E. cilicica, minor clusters were also identified in the terminal regions of one metacentric chromosome pair. The number and distribution of 5S rDNA clusters is more specific. In E. cilicica, two major clusters were identified in the pericentromeric region of a pair of metacentric chromosomes. For E. longistipitata we observed two major clusters in the pericentromeric region of a pair of submetacentric chromosomes and two major clusters in the interstitial region of a pair of metacentric chromosomes. E. hyemalis has many clusters of different sizes, localized mainly in the pericentromeric regions. Summarizing new data on the karyotype structure of E. sect. Eranthis and previously obtained data on E. sect. Shibateranthis allowed the conclusion about clear interspecific karyological differences of the genus Eranthis.
... At the C-4 position, methoxy or hydroxyl groups can serve as a substituent; at position C-7, methoxy groups and glucose; and at position C-9, a methoxy group, or-as in 15, 17, 19, and 21-the substituent may be absent. Khellol (17) represents an aglycone of khellol glucoside (18), in which the sugar moiety is attached at position C-7. In the genus Eranthis, most research on furochromones of this subclass has been conducted on samples of the aerial parts (leaves, stems, and flowers) of E. pinnatifida Maxim., E. hyemalis, and E. longistipitata [24][25][26][27], and only compound 21 has been detected in an underground part (tubers) of E. cilicica [21]. ...
This review summarizes information about the chemical composition and beneficial properties of species of the genus Eranthis Salisb. from the world's flora. To date, seven out of ~14 species found in Asia and parts of Europe have been studied to various degrees. Here, data are presented on the diversity of sets of chromones, furochromones, triterpene saponins, coumarins, and other classes of secondary metabolites of Eranthis species according to the literature. For new compounds-isolated from Eranthis for the first time-structural formulas are also provided. Among the new compounds, chromones and coumarins predominate, as do triterpene saponins of the olean and cycloartane series and lectin. The results of pharmacological studies are presented showing anti-inflammatory, antioxidant, antiviral, and other types of biological activities found in extracts, in their fractions, and in individual compounds of the aboveground and underground organs and parts of Eranthis species. Despite the limited geographic range of Eranthis plants, it is possible to search for active substances, develop methods for biological and chemical synthesis of the isolated substances, and create a finished therapeutic substance based on them. In addition, it is feasible to obtain the desired standardized pure materials from Eranthis species grown in vitro.
... According to the work of Huang and Zhang (2022) on Eranthis, the length of the claw varies among species and several species display pseudonectaries. There is always an outgrowth on the adaxial side. ...
... Even if these structures mimic nectar that is not present on the bulge, nectar is present elsewhere on these petals, in the median or proximal zone. In this case, pseudonectaries not only attract pollinators but also help pollinators find the nectar that is sometimes hidden in a funnel-shaped outgrowth like in Eranthis (Huang and Zhang, 2022) or inside a nectar chamber like in Nigella (Weber, 1995). The expression of several genes involved in chloroplast development, cell division and wax formation have been found enriched in pseudonectary tissue in N. damascena. ...
Ranunculaceae comprise ca. 2,500 species (ca. 55 genera) that display a broad range of floral diversity, particularly at the level of the perianth. Petals, when present, are often referred to as “elaborate” because they have a complex morphology. In addition, the petals usually produce and store nectar, which gives them a crucial functional role in the interaction with pollinators. Its morphological diversity and species richness make this family a particularly suitable model group for studying the evolution of complex morphologies. Our aims are (1) to reconstruct the ancestral form of the petal and evolutionary stages at the scale of Ranunculaceae, (2) to test the hypothesis that there are morphogenetic regions on the petal that are common to all species and that interspecific morphological diversity may be due to differences in the relative proportions of these regions during development. We scored and analyzed traits (descriptors) that characterize in detail the complexity of mature petal morphology in 32 genera. Furthermore, we described petal development using high resolution X-Ray computed tomography (HRX-CT) in six species with contrasting petal forms (Ficaria verna, Helleborus orientalis, Staphisagria picta, Aconitum napellus, Nigella damascena, Aquilegia vulgaris). Ancestral state reconstruction was performed using a robust and dated phylogeny of the family, allowing us to produce new hypotheses for petal evolution in Ranunculaceae. Our results suggest a flat ancestral petal with a short claw for the entire family and for the ancestors of all tribes except Adonideae. The elaborate petals that are present in different lineages have evolved independently, and similar morphologies are the result of convergent evolution.
... Kram et al. [113] showed that the number of dictyosomes in secretory cells increased gradually before and during secretion. The ultrastructure of floral nectary exhibited the presence of Golgi apparatus and an extensive ER network in many plant species [20,68,85,113,114]. This study and literature data reported the presence of Golgi apparatus, mitochondria, ER profiles, and dictyosome vesicles in the vicinity of the plasmalemma. ...
The distinctive features of floral nectaries facilitate identification of ecological and phylogenetic links between related taxa. The structure and functioning of nectaries determine the relationships between plants, pollinators, and the environment. The aim of the study was to determine and compare the micromorphology of the epidermis in the floral nectaries of six Rubus idaeus cultivars belonging to biennial (‘Glen Ample’, ‘Laszka’, ‘Radziejowa’) and repeated fruiting (‘Pokusa’, ‘Polana’, ‘Polka’) groups. Another objective was to characterize the cuticle ornamentation and stomatal morphology, the anatomy of the nectary epidermis, parenchyma, and sub-nectary parenchyma in the initial nectar secretion phase, as well as the ultrastructure of the nectary epidermis and parenchyma cells in the initial and full nectar secretion phases. The study was carried out using light, fluorescence, scanning and transmission-electron microscopy techniques. Semi-thin and ultrathin sections were used for the microscopic analyses. The cuticular ornamentation and stomatal morphology may be helpful elements in the identification of relatedness between Rubus species. The interaction of the extensive system of endoplasmic reticulum membranes, mitochondria, and Golgi apparatus indicates high metabolic activity, and the fusion of transport vesicles with the membrane suggests granulocrine nectar secretion. The results bring new data to the biology of plants.
... The release of nectar into the perianth tube proceeded via diffusion through the polysaccharide microchannels present in the reticulate papilla cuticle. This mode of nectar release has been described in nectary glands of many mono-and dicotyledonous plant species (Margońska et al., 2021;Huang and Zhang, 2022). As shown by Stpiczyńska et al. (2021), both hydrophobic and hydrophilic nectar components are transported through cuticle microchannels. ...
The insufficient pollinator visitation is the most important limitation of fruit and seed production, which is common and ubiquitous in entomophilous angiosperms. The scent and attractive colours with flower guides and such floral rewards as nectar, pollen, and oil are important attractants for insects visiting and pollinating flowers in the family Iridaceae. The aim of this study was to investigate the morphology of flowers and the micromorphology, anatomy, and ultrastructure of floral nectaries in the rare and endangered species Iris sibirica with the use of light, scanning, and transmission electron microscopes and histochemical assays. Osmophores in the form of papillae were located on the adaxial surface of outer tepals and on the abaxial surface of the stylodium channel. The nectaries were located on the inner surface of the perianth tube and were composed of a single-layered epidermis with papillae and several layers of glandular parenchyma with vascular bundles. I. sibirica nectaries represent the presecretory starch-accumulating type, where nectar is released for a short time immediately after flower opening. Nectar was produced throughout the flower lifespan in both male and female stages. It was secreted in the granulocrine mode and released through microchannels in the reticulate cuticle of nectary papillae. Transport of pre-nectar components proceeded via symplastic and apoplastic pathways. The nectary epidermal cells with papillae and glandular parenchyma cells contained total lipids, acidic lipids, and polysaccharides, whereas the epidermal cells with papillae additionally contained neutral lipids and polyphenol compounds. The nectaries and nectar production in I. sibirica flowers share the common location and follow several secretion patterns characteristic for the nectaries in some members of the family Iridaceae and the subfamily Iridoideae. Nevertheless, the mode of nectar release through the cuticle of epidermal papillae has been described in Iridaceae family for the first time. The visual, aromatic, and food attractants characteristic of I. sibirica flowers probably stimulate potential visits by pollinators, but the short nectar secretion period may limit the effectiveness of pollinators and sexual reproductive success.
Trollius europeus L. flowers produce nectar available to various groups of insects. No anatomical studies of these floral nectaries have been conducted to date. This study presents the structure of nectaries at different levels of organisation and the characteristics of petaloids, nectary leaves (petals), and stamens, including their micromorphology. The analyses of the nectaries were carried out with the use of light, fluorescence, scanning electron, and transmission electron microscopy techniques.
The nectary located in a small cavity on the nectary leaf consists of the epidermis, nectar-producing parenchyma, and subnectary parenchyma, which has three large vascular bundles containing phloem and xylem. Amyloplasts with starch granules are present only in the parenchyma surrounding the vascular bundles. The other cells of the nectary parenchyma contain only chromoplasts with large plastoglobules. Since there are no chloroplasts, sugars required for nectar production are assumed to originate from phloem sap. The numerous plasmodesmata in the cell walls indicate a symplastic route of pre-nectar. Nectar is secreted onto the nectary surface in the holocrine mode. After disorganisation of the cytoplasmic structure, the epidermal cell wall is disrupted and the cell contents along with the nectar are released into the depression on the nectary leaf. The secretion of nectar from cells is non-synchronous and lasts 4-5 days. The content of nectar proteins and lipids derived from the cytoplasm of epidermal cells increases the nutritional value of the secretion, which may be important for pollinators.
