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Location of the nectary in G. nivalis flowers (a,b,f LM; c-e FM). a Nectary located at the apex of the inferior ovary between the bases of the tepals and the style; visible projections of whitish nectariferous tissue between the filaments. b Nectary disc with visible shimmering nectar (arrow) accumulated in the concavities surrounding the filaments and the style. c,d Longitudinal section of the floral nectary at the initial phase of nectar secretion; visible outer layers of the gland, blue (c) and green (d) fluorescence of the gland layers (stage II); FM. e More intense fluorescence of the nectary layer in an older flower (stage IV); FM. f Protrusion of the nectary tissues between the style base and the filament; visible orange-stained cutinized layers. c-e After application of the DAPI filter (c), after addition of auramine O and using the FITC filter (d), autofluorescence (e), after treatment with Sudan III (f). f-filament; n-nectary; o-ovary; s-style; t-tepal.
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In Poland Galanthus nivalis L. is partially protected. The flowers of this species are one of the first sources of nectar and pollen for insects from February to April. The aim of this study was to present the flowering biology as well as the topography, anatomical, and ultrastructural features of the floral nectary. The flower lifespan, the breedi...
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... nectary of the Galanthus nivalis flowers (Fig. 3a) was located at the top of the in- ferior ovary between the tepals and the style. The green whitish nectary layer was situ- ated above the green tissues of the ovary (Fig. 3a,b). Nectary tissues formed conical convexities between the filaments and style (Fig. 3e, Fig. 4a) and circular concavities filled with nectar at their bases (Fig. ...
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... nectary of the Galanthus nivalis flowers (Fig. 3a) was located at the top of the in- ferior ovary between the tepals and the style. The green whitish nectary layer was situ- ated above the green tissues of the ovary (Fig. 3a,b). Nectary tissues formed conical convexities between the filaments and style (Fig. 3e, Fig. 4a) and circular concavities filled with nectar at their bases (Fig. 3a,b). The outer walls of the nectary epidermal cells viewed in SEM were characterized by striated cuticular ornamentation, which was well visible already in the pre-secretory ...
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... nectary of the Galanthus nivalis flowers (Fig. 3a) was located at the top of the in- ferior ovary between the tepals and the style. The green whitish nectary layer was situ- ated above the green tissues of the ovary (Fig. 3a,b). Nectary tissues formed conical convexities between the filaments and style (Fig. 3e, Fig. 4a) and circular concavities filled with nectar at their bases (Fig. 3a,b). The outer walls of the nectary epidermal cells viewed in SEM were characterized by striated cuticular ornamentation, which was well visible already in the pre-secretory phase. The undulating, parallel, densely arranged striae in adjacent cells often exhib- ited ...
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... flowers (Fig. 3a) was located at the top of the in- ferior ovary between the tepals and the style. The green whitish nectary layer was situ- ated above the green tissues of the ovary (Fig. 3a,b). Nectary tissues formed conical convexities between the filaments and style (Fig. 3e, Fig. 4a) and circular concavities filled with nectar at their bases (Fig. 3a,b). The outer walls of the nectary epidermal cells viewed in SEM were characterized by striated cuticular ornamentation, which was well visible already in the pre-secretory phase. The undulating, parallel, densely arranged striae in adjacent cells often exhib- ited varied orientation. They were more loosely arranged at the cell borders ...
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... to nectar secretion, the nectary epidermis exhibited light green epifluorescence after the treatment with auramine O and the use of the FITC filter (Fig. 3d), or bright blue epifluorescence when the DAPI filter was used (Fig. 3c). As shown by fluores- cence microscopy, the layer of the nectary glandular cells was distinguished from the ovary and receptacle tissues by distinct fluorescence (Fig. 3e). The outer walls of the epidermal cells exhibited the presence of a cutinized layer after the ...
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... to nectar secretion, the nectary epidermis exhibited light green epifluorescence after the treatment with auramine O and the use of the FITC filter (Fig. 3d), or bright blue epifluorescence when the DAPI filter was used (Fig. 3c). As shown by fluores- cence microscopy, the layer of the nectary glandular cells was distinguished from the ovary and receptacle tissues by distinct fluorescence (Fig. 3e). The outer walls of the epidermal cells exhibited the presence of a cutinized layer after the application Tab. 4 Outcrossing index and breeding system of Galanthus ...
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... exhibited light green epifluorescence after the treatment with auramine O and the use of the FITC filter (Fig. 3d), or bright blue epifluorescence when the DAPI filter was used (Fig. 3c). As shown by fluores- cence microscopy, the layer of the nectary glandular cells was distinguished from the ovary and receptacle tissues by distinct fluorescence (Fig. 3e). The outer walls of the epidermal cells exhibited the presence of a cutinized layer after the application Tab. 4 Outcrossing index and breeding system of Galanthus ...
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... Sudan III (Fig. 3f, Fig. 5c). Nectar drops were visible in the cross sections of fresh nectary tissues (Fig. 5c), which corresponds with our SEM observations. The nectary gland in the flowers of G. nivalis is composed of one layer of epidermal cells, 7-10 layers of glandular parenchymal cells, and several layers of sub-nectary parenchyma (Fig. 5a). These layers ...
Citations
... With respect to floral exudates, a number of recent studies have quantified changes in exudate composition in floral secretions in relation to environment (Buchmann, 1987;Roshchina and Roshchina, 1993;Bernardello et al., 1999;Nicolson et al., 2007;Devoto et al., 2006;Cosacov et al., 2012;Ferreiro et al., 2015;Mittelbach et al., 2015;Roy et al., 2017;Domingos-Melo et al., 2020;Saddhe et al., 2021). Research has shown that temperature, salinity, soil nutrients, light, and water, may increase or decrease the volume of secreted floral exudates or even the amounts of certain nectar constituents (Schneider and McNally, 1992;Pacini et al., 2003;Galetto and Bernardello, 2004;Brandenburg et al., 2009;Weryszko-Chmielewska and Chwil, 2016;Aleixo et al., 2017;Graves et al., 2017;Saddhe et al., 2021). ...
Resource allocation in floral exudate composition is a trade-off between energy cost to the plant and pollinator reward. For example, carbohydrates offer less reward to pollinators but at less cost to the plant when compared with lipids. We suggest plant and community allocation to carbohydrates and lipids may vary across environmental gradients, with plants in resource-limited communities able to allocate fewer resources to higher-cost compounds in floral exudates. Plant and community resource allocation is important for understanding the behavior of pollinators and understanding how it relates to environment may help predict changes in behavior in response to climate change. In this study, we characterized the composition of floral exudates across three sites across a water resource availability gradient. Our results allow us to reject the hypothesis that fewer resources are allocated to pollinator reward in water-poor environments and we suggest that this may be due to increased pollinator competition. Our results also highlight the prevalence of pectins in floral exudates in drier environments, supporting the hypothesis that pectins are required to prevent exudates from crystallizing in drier environments.
... Few studies have discussed nectaries and nectar in the Galanthus genus. Some older studies reported [36] that nectar is secreted from a nectary pad on the top of an inferior ovary and that Galanthus has two types of nectaries: one on the inside of perigon flowers (epidermal cells) ( Figure 2) and the other in the shape of a disc on the flower base ( Figure 3). Otherwise, the latest studies only confirmed one type. ...
... Otherwise, the latest studies only confirmed one type. On the top of the inferior ovary, between the base of the perigon leaves and the style, the nectariferous layer forms a bright area in contrast with a green receptacle fused with the ovary [34,36]. G. nivalis grows in forests, on forest edges, between bushes, and on meadows from the lowlands to the lower mountains. ...
... This species also plays an important role in bees' li known that this species has a lot of pollen, but it is not so known for its nec studies have discussed nectaries and nectar in the Galanthus genus. Some older reported [36] that nectar is secreted from a nectary pad on the top of an inferior ov that Galanthus has two types of nectaries: one on the inside of perigon flowers (ep cells) ( Figure 2) and the other in the shape of a disc on the flower base ( Figure 3) wise, the latest studies only confirmed one type. On the top of the inferior ovary, the base of the perigon leaves and the style, the nectariferous layer forms a brigh contrast with a green receptacle fused with the ovary [34,36]. ...
Floral nectar is mainly a reward in the form of food for pollinators. In early spring, when snow can still be present, pollinators have trouble finding food. The composition and productivity of nectar in flowers play an important role in a pollinator’s life. It is known that low temperatures and lower humidity cause lower nectar secretion. Some studies have also shown that the quality of nectar can differ because of lower temperatures. In our research, we analysed whether abiotic factors affect nectar secretion, as well as the nectar composition of the early spring plant species Galanthus nivalis L. and Helleborus niger L. in February 2024. The study was conducted in two locations in nature. Nectar from H. niger was sampled in Tomišelj, Slovenia, whereas nectar from G. nivalis was sampled in Ljubljana, Slovenia. On four different days at three different times of day, we sampled nectar from flowers using microcapillaries. In total, we sampled 48 nectar samples from one species. We analysed soil humidity and temperature, air temperature and humidity, and UVB radiation. Our results show that nectar productivity is highest in the morning for both species. H. niger has sucrose-dominant nectar, while G. nivalis has hexose-dominant nectar. Proline, which is an important amino acid for bees, has the highest level in both species, as does the phenolic compound rutin. Environmental factors do affect nectar secretion. Soil and air temperature affect G. nivalis nectar secretion, while soil humidity affects H. niger nectar secretion. Soil and air temperature also have an effect on higher levels of sugars in both researched nectars. UVB, air humidity, and air and soil temperature seem to have an effect on phenolic compounds, but abiotic factors do not affect amino acids.
... G. nivalis in Poland occurs mainly in the southern and central parts of the country, but it can also be found in the Lublin region. It is a species characteristic of deciduous forests [28]. L. vernum occurs naturally in the Lower Silesian Voivodeship-Trzebnickie Hills and Oleśnicka Plain [29], as well as the Carpathian Mountains [30]. ...
The protection of biological diversity in nature and in agriculture, including the production of ornamental crops, has become increasingly important in Poland as well as worldwide. The Convention on Biological Diversity, signed in 1992 at the Earth Summit of the UN in Rio de Janeiro and ratified by the Polish government in 1995, imposed new regulations related to the protection of nature and the genetic resources of cultivated crops in Poland. The conservation of the genera, varieties and cultivars of ornamental geophytes—a group of plants of great interest from a botanical and physiological, but also a horticultural point of view—takes place in situ (both in nature and in the places of cultivation) and through the establishment of ex situ gene banks and collections. The natural genetic resources of ornamental geophytes include species from the genera Allium, Fritillaria, Gladiolus, Iris, Leucojum, Lilium and Muscari, among others, and more than a dozen species are protected by law due to varying degrees of threats. Botanical gardens play an essential role in the conservation of endangered species. Their activities focus on genus monitoring, managing ex situ gene banks (including National Collections), developing propagation methods and carrying out their reintroduction. In order to protect the national genetic resources of cultivated plants, the National Centre for Plant Genetic Resources at the Plant Breeding and Acclimatisation Institute—National Research Institute, under the auspices of the Ministry of Agriculture and Rural Development, was established. Concerning ornamental geophytes, the National Centre coordinates two field collections of cultivars of the genera Gladiolus, Lilium, Narcissus and Tulipa, which are of great economic importance and have a long tradition of breeding in Poland. The first one is located at the National Institute of Horticultural Research in Skierniewice (central Poland), and the second one is at the Experimental Substation of Variety Testing in Lisewo (northern Poland). The history of tulip collections in Poland dates back to the 1960s. At that time, the first breeding work for this species began. The collection of bulbous crops in Skierniewice is currently one of the largest in Poland, with a total of 934 accessions. Most of them are tulips (522) and lilies (222). Other plants in the collection in Skierniewice are gladiolus and narcissus. The most valuable accessions are grown under special protection (tunnels with dense nets) to guard against insects and maintain a mild climate inside. The genetic resources of the ornamental bulb plant collection in Lisewo currently consist of 611 accessions, mainly tulips (358), daffodils (121) and gladioli (132). All bulbous crops in both collections (Skierniewice and Lisewo) are grown in accordance with all principles of agrotechnics (negative field selection, fertilisation, soil maintenance). A particularly important task of botanical gardens, universities, research institutes and the National Centre is leading research on the methods of storage for survival organs, in vitro cultures and cryopreservation. We have discovered that the various activities for the species conservation of ornamental geophytes require a great deal of constantly deepening knowledge and extraordinary measures, including frequent monitoring of the effects of the applied measures.
... Their height was in the range of 2.8-3.3 µm in several species of the genus Prunus [60]. Similar protuberances were described in representatives of the genera Aesculus, Galanthus, Prunus, and Rhododendron [20,60,[75][76][77]. ...
... Horner et al. [101] and García et al. [102] reported the presence of smooth and rough endoplasmic reticulum in nectary epidermis and parenchyma cells in Glycine max and Passiflora spp. In turn, rough endoplasmic reticulum was found in nectary cells in Citharexylum myrianthum, Erythrina speciosa, Prunus laurocerasus, Prunus persica, and Robinia viscosa [72,76,[103][104][105][106], whereas a smooth endoplasmic reticulum was observed in Geranium macrorrhizum and G. phaeum and several species from the families Anacardiaceae and Orchidaceae [82,96,106,107]. Different types of endoplasmic reticulum membranes in nectary cell protoplasts have been described. ...
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.
... Although ants are a major selective force toward seed dispersal by arthropods (e.g., [11]), we observed low rates of diaspore dispersal in three myrmecochorous early flowering plants interacting with two ant species of small and moderate size. These results are particularly surprising for the snowdrop, because this plant is at least partly self-compatible [52] and selfing plants are expected to invest more in seed dispersal relative to plants with a high outcrossing rate [53]. ...
Simple Summary
Myrmecochory is seed dispersal of numerous plant species mediated by ants. We investigate ant–plant interactions under field conditions across two study sites in Central Europe. Three obligatory myrmecocohrous plants are chosen for the experiments: snowdrop Galanthus nivalis, hollow root Corydalis cava and European wild ginger Asarum europaeum. We experimentally alter diaspore morphology and record seed removal rates across five treatments: elaiosomes without seeds, diaspore without elaiosome, 1/2 elaiosome + diaspore, 1/2 diaspore + elaiosome and control. Elaiosomes of European wild ginger constitute about 30% of diaspore weight, elaiosomes of snowdrop constitute 13% and elaiosomes of hollow root constitute only 7.5%. Diaspore/elaiosome removal rates are highest in European wild ginger (34%), followed by hollow root (26%) and snowdrop (10%). Only two ants interact with diaspores, the acorn ant Temnothorax crassispinus and the red ant Myrmica ruginodis. Ants respond to elaiosome/seed ratio by removing elaiosomes without diaspores most frequently, followed by 1/2 diaspore + elaiosome, control, diaspores without elaiosomes and 1/2 elaiosome with diaspore. Plants do not effectively manipulate ant behavior and no dispersal benefits from interactions with ants are observed.
Abstract
Interactions between ants and plants vary from being occasionally beneficial to neutral and negative. Ant-mediated dispersal of obligatory myrmecochorous plants is considered mutualistic interaction, providing benefits to plants in terms of seed dispersal. Ants are rewarded by providing elaiosome, sugar, lipid and protein-rich appendages attached to seeds (diaspores). We experimentally examine rates of diaspore removal rates among three species of plants (snowdrop Galanthus nivalis, hollow root Corydalis cava and European wild ginger Asarum europaeum) under field conditions in two study sites in Central Europe. Diaspore morphology is altered by manipulating both elaiosome and seed size. The small-sized acorn ant Temnothorax crassispinus interacts with the snowdrop and hollow root and the moderately-sized red ant Myrmica ruginodis interacts with European wild ginger. Experimental manipulation with elaiosomes yields largely non-significant results. Diaspore removal rates are generally low (snowdrop 10%, hollow root 26%, European wild ginger 34%) probably due to the small size of ants relative to heavy diaspores. Many ants are observed to consume elaiosomes in situ (cheating). We conclude that ant–plant relationships in this case are not mutualistic but rather neutral/slightly negative, because the plants do not obtain any apparent benefits from their interactions with ants.
... 35 Several reports suggested that snowdrops have green patterned inner tepals attracting and guiding pollinators with visual and/or olfactory displays. [36][37][38][39] To our best knowledge, however, no study investigated the role of green marks of snowdrop flowers in pollinator attraction experimentally. Moreover, snowdrop has a consistent downward floral orientation, but its significance in pollinator attraction remains unclear. ...
... Green marks on abaxial snowdrop tepals were hypothesized to guide/attract pollinators. 38,39 Laboratory tests showed that naïve bumblebees prefer model flowers with contrasting colors over monochromatic models. 49 This suggests that conspicuous tepal spots may be easier to detect, and thus be effective in attracting pollinators, 26 a character that is beneficial to the plant, because spots are placed close to the location of rewards. ...
... Green marks on both sides of the inner tepals produce odorous substances that are predicted to attract pollinators. 39 We suggest that these odor scents help the flower to guide pollinators to their rewards after the pollinator approaches the flower. Odor scents appear to play no significant role in experimentally altered flowers with upward corollas. ...
Flower shapes, colors, sizes and fragrances are shaped mostly for pollinator attraction. Flower phenotypes are, however, subjected to conflicting selection directed by both pollinators and non-pollinating agents. We investigated flower attractiveness to a model pollinator in the snowdrop (Galanthus nivalis L.) under laboratory conditions. Naïve bumblebees (Bombus terrestris L.) showed strong, innate preferences for experimentally altered upward positioned flowers, suggesting that the natural, downward orientation did not evolve to attract pollinators. Experimentally treated green marks on inner tepals decreased pollinator attraction compared with flowers expressing intact marks, suggesting that green marks serve to guide/ attract pollinators. Attractiveness of green marks was significantly compromised by flower orientation; green marks were attractive only for untreated downward-oriented flowers, but they did not improve the attractiveness of upward-oriented flowers. Our results suggest that downward flowers in snowdrop evolved under conflicting selection directed by biotic and abiotic factors, and that green marks on inner tepals could evolve later to enhance flower attractiveness.
... Secretion release in plants generally requires (except for exudates released through the stomata) the accumulation of secretory products in the subcuticular space and subsequent exudation via cuticular ruptures [57]. In most known cases, hydrophilic pathways throughout the cuticle appear as channels of cell wall elements crossing the cuticle, rather than true ducts delimiting empty lumens [57][58][59]. Nevertheless, cuticle pores resembling those observed in T. cyanea have been described for, at least, nectaries of Abutilon [60] and Spathodea campanulata [57]. ...
Bromeliad scales have been investigated extensively due to their recognition as a key ecological and evolutionary feature of Bromeliaceae. However, much remains unknown about such trichomes and only recently mucilage exudation was described for them in a species of the subfamily Bromelioideae. The present study aimed to investigate the secretion present in inflorescences of Tillandsia cyanea Linden ex K. Koch (Tillandsioideae) to determine whether the scales of this species also produce and release secretions. Samples of young and mature portions of inflorescences were collected and prepared according to standard methods for light and electron microscopy. Anatomical and ultrastructural results indicate that the secretion is produced by the wing portion of typical peltate trichomes on the adaxial surface of bracts. The secretory activity begins in the early stages of trichome expansion and characteristically occurs in cells exhibiting a porous cuticle and dense cytoplasm with numerous mitochondria and dictyosomes. Histochemical tests confirmed mucilage secretion and revealed proteins in the exudate. These data comprise the first record of mucilage exudation by trichomes within Tillandsioideae and indicate that this capacity may be more relevant to bromeliad biology than previously considered. Functional aspects and colleter-like activity are also discussed.
... Hydrophilic bridges formed by wall elements and pectin appear to be nectar release routes, allowing passage through the cuticle, as pointed-out by Paiva (2017). Similar hydrophilic pathways crossing the cuticle have been described for stomata-free floral nectaries in Orchidaceae (Stpiczynska, 2003) and other plant families (Antón and Kamińska, 2015;Weryszko-Chmielewska and Chwil, 2016). Considering this hypothesis, nectar flow must be slow and continuous toward the petal surface because it needs to pass through countless ramifications of hydrophilic projections within the cuticular layer (Paiva, 2017). ...
The specialised mutualism between Tococa guianensis and ants housed in its leaf domatia is a well-known example of myrmecophily. A pollination study on this species revealed that flowers in the bud stage exude a sugary solution that is collected by ants. Given the presence of this unexpected nectar secretion, we investigated how, where, and when floral buds of T. guianensis secret nectar and what function it serves. We studied a population of T. guianensis occurring in a swampy area in the Cerrado of Brazil by analyzing the chemical composition and secretion dynamics of the floral-bud nectar and the distribution and ultrastructure of secretory tissues. We also measured flower damage using ant-exclusion experiments. Floral bud nectar was secreted at the tip of the petals, which lack a typical glandular structure but possess distinctive mesophyll due to the presence of numerous calcium oxalate crystals. The nectar, the production of which ceased after flower opening, was composed mainly of sucrose and low amounts of glucose and fructose. Nectar was consumed by generalist ants and sporadically by stingless bees. Ant exclusion experiments resulted in significantly increased flower damage. The floral nectar of T. guianensis is produced during the bud stage. This bud-nectar has the extranuptial function of attracting generalist ants that reduce florivory. Pollen is the unique floral resource attracting pollinators during anthesis. Tococa guianensis, thus, establishes relationships with two functional groups of ant species: specialist ants acting against herbivory and generalist ants acting against florivory.
... The flowers of G. nivalis are one of the first sources of nectar and pollen for insects from February to April. The lifespan of unpollinated flowers is 20-30 days, while that of pollinated flowers is much shorter (3-15 days) (Weryszko-Chmielewska and Chwil, 2016). ...
... The flower of G. nivalis is adapted to the early spring thermal conditions (Erdelská, 2018). Weryszko-Chmielewska and Chwil (2016) show that the phenology of the snowdrop takes place in a thermal regime ranging from −0.8°C to +8.5°C; on most days remaining in the range of 4-7°C. At 7−8°C bees were observed collecting nectar and pollen from the G. nivalis flowers. ...
The present research studies the pollen biology of snowdrop (Galanthus nivalis L.), from the point of view of pollen’s germinating potential and length growth of pollen tubes at two temperatures: 18 °C and 4 °C. The germination was conducted “in vitro” on nutritive mediums containing different concentrations of sucrose (0, 5, 10, 15, 20, 25, 40, 50, 70, 100%). The pollen germination was optimum (more than 90 %) on nutritive mediums containing 15 % and 20 % sucrose, at both studied temperatures, after 24 h. In parallel with germination potential, the adaptation of male gametophytes to the two temperatures was analyzed. The longest pollen tubes were formed on 10–25% sucrose mediums at 18 °C and on 10–15% sucrose mediums at 4 °C, and they were maintained also after 120 h since pollen inoculation. For these concentrations, the pollen tube length was similar at both temperatures. In conclusion, 18 °C is suitable for long tubes formation using a largest range of sucrose concentration than 4 °C. In fact, in most plant species, low temperatures not only inhibit pollen tube growth, but also induce flowers abortion. Present results bring new evidences that the snowdrop’s male gametophyte is genetically settled to have a normal development at low temperatures. The optimal germination rate and pollen tube growth at 4 °C highlight the vernal character of the pollen of G. nivalis.
... Such a structure has been described in the cells of various nectary types in many species (e.g. Stpiczyńska 2003;Wist and Davis 2006;Rocha and Machado 2009;Antoń and Kamińska 2015;Weryszko-Chmielewska and Chwil 2016) as well as in other plant glandular structures-osmophores (García et al. 2007;Płachno et al. 2010;Kowalkowska et al. 2012Kowalkowska et al. , 2014Kowalkowska et al. , 2017Paiva et al. 2019), collectors (Tresmondi et al. 2017) and trichomes, which produce a lipophilic secretion Muravnik et al. 2019). Interestingly, we found polysaccharide micro-canals in the cuticular layer of the spur papillae. ...
Pinguicula (Lentibulariaceae) is a genus comprising around 96 species of herbaceous, carnivorous plants, which are extremely diverse in flower size, colour and spur length and structure as well as pollination strategy. In Pinguicula, nectar is formed in the flower spur; however, there is a gap in the knowledge about the nectary trichome structure in this genus. Our aim was to compare the nectary trichome structure of various Pinguicula species in order to determine whether there are any differences among the species in this genus. The taxa that were sampled were Pinguicula moctezumae, P. moranensis, P. rectifolia, P. emarginata and P. esseriana. We used light microscopy, histochemistry, scanning and transmission electron microscopy to address those aims. We show a conservative nectary trichome structure and spur anatomy in various Mexican Pinguicula species. The gross structural similarities between the examined species were the spur anatomy, the occurrence of papillae, the architecture of the nectary trichomes and the ultrastructure characters of the trichome cells. However, there were some differences in the spur length, the size of spur trichomes, the occurrence of starch grains in the spur parenchyma and the occurrence of cell wall ingrowths in the terminal cells of the nectary trichomes. Similar nectary capitate trichomes, as are described here, were recorded in the spurs of species from other Lentibulariaceae genera. There are many ultrastructural similarities between the cells of nectary trichomes in Pinguicula and Utricularia.
