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A survey of mucilage cells in vegetative organs of the dicotyledons
... In Malvaceae, secretory canals/ducts and cavities, idioblasts, trichomes, and nectaries are very frequent and, in general, have mucilage as the main exudate, which is observed in both vegetative and reproductive organs (Metcalfe & Chalk 1957;Scott & Bystrom 1970;Gregory & Baas 1989;Sawidis 1991Sawidis , 1998. Some studies point out that secretory structures constitute synapomorphies for the order Malvales (Alverson et al. 1998(Alverson et al. , 1999Judd et al. 2009); the which first anatomical description was made for Althaea (L.) (Malvaceae) by Meyer in 1837 (Gregory & Baas 1989). ...
... In Malvaceae, secretory canals/ducts and cavities, idioblasts, trichomes, and nectaries are very frequent and, in general, have mucilage as the main exudate, which is observed in both vegetative and reproductive organs (Metcalfe & Chalk 1957;Scott & Bystrom 1970;Gregory & Baas 1989;Sawidis 1991Sawidis , 1998. Some studies point out that secretory structures constitute synapomorphies for the order Malvales (Alverson et al. 1998(Alverson et al. , 1999Judd et al. 2009); the which first anatomical description was made for Althaea (L.) (Malvaceae) by Meyer in 1837 (Gregory & Baas 1989). ...
... Nonetheless, the secretory structures identified in the species of Ceiba studied here included mucilaginous, crystalliferous and phenolic idioblasts, clavate-type glandular trichomes, and extrafloral nectaries. Such structures are ordinary and follow the records found in the literature, both for Malvaceae and Bombacoideae (Gregory & Baas 1989;Pimentel et al. 2011;Rocha et al. 2011), except for extrafloral nectaries, which, to the best of our knowledge, is the first record for the genus. The term idioblast defines cells that differ from others by their shape, size, or content (Fahn 1979;Crang et al. 2018). ...
The description of secretory structures in Malvaceae is controversial, and results in conflicting interpretations. Amid conflicting interpretations, therefore, the present study aims to describe the ontogeny diversity and histochemistry in Ceiba, emphasizing the secretory structures in leaves of C. erianthos, C. jasminodora, C. pentandra, and C. speciosa. All analyzed species present mucilaginous, crystalliferous, and phenolic idioblasts. These structures are randomly arranged in the mesophyll, epidermis, petiole cortex, and parenchymatic tissue of the midrib. However, in C. jasminodora and C. pentandra, secretory structures are only found in the midrib area. The development of mucilaginous idioblasts is asynchronous and, when mature, they coalesce forming large structures full of mucilage. Clavate-type pluricellular glandular trichomes were also detected scattered randomly on both leaf surfaces. Their ontogeny is described, and histochemical tests showed the presence of lipophilic substances. Extrafloral nectaries were observed in the middle third of the midrib, on the abaxial side of the leaflets. They originate from the protoderm and ground meristem of the midrib cortex. It is expected that these results will help consolidate knowledge of secretory structures in Malvaceae, leading, in turn, to the elucidation of phylogenetic relationships.
... The presence of phenolic compounds is referred to as a group of substances of great importance in protection against herbivores, microorganisms, excess ultraviolet radiation and also to help the cell protoplast to maintain its integrity when subjected to water stress [25] . Pharmacologically, phenolic substances have astringent, healing, antiseptic, antioxidant, vasoconstrictor, hemostatic and anti-inflammatory properties [23,26] [27] . These substances can perform different functions in plants, including the protection of developing structures and organs, water retention, carbohydrate reserves, reduction of transpiration, protection against radiation by scattering or reflecting incident light, protection against herbivory, lubricating root apices, insect capture in insectivorous plants, as an adhesive in seed dispersal and in the regulation of seed germination [10,27] . ...
... Pharmacologically, phenolic substances have astringent, healing, antiseptic, antioxidant, vasoconstrictor, hemostatic and anti-inflammatory properties [23,26] [27] . These substances can perform different functions in plants, including the protection of developing structures and organs, water retention, carbohydrate reserves, reduction of transpiration, protection against radiation by scattering or reflecting incident light, protection against herbivory, lubricating root apices, insect capture in insectivorous plants, as an adhesive in seed dispersal and in the regulation of seed germination [10,27] . ...
... The mucilage present in the secretory trichomes and idioblasts of the studied species is composed of acidic and neutral polysaccharides and phenolic substances. suggests that in Althaea officinalis L. different fractions of mucilage have different functions [27] . Water storage is carried out by the acid fraction, which has its production peak in the summer months and the storage of carbohydrates is done by the neutral fraction, which has its maximum production during the winter. ...
Paullinia é um gênero monofilético de lianas com distribuição neotropical, abrangendo aproximadamente 220 espécies. No Brasil, existem 102 espécies ocorrendo principalmente nos domínios fitogeográficos da Mata Atlântica e Amazônia. As espécies deste gênero possuem diversos usos como psicotrópicos, bactericidas, antioxidantes, venenos de peixes, estimulantes e para fins ritualísticos. O gênero é, no entanto, pouco estudado do ponto de vista anatômico e histoquímico. No presente estudo, foram feitas investigações morfoanatômicas e histoquímicas das folhas de Paullinia dasygonia Radlk., P. micrantha Cambess. e P. trigonia Vell. As espécies estudadas possuem caracteres foliares muito semelhantes, o que dificulta sua identificação. As folhas apresentam estrutura dorsiventral, apresentam feixes vasculares colaterais e tricomas tectores e glandulares que variam nas espécies quanto à forma, comprimento e distribuição. Os tricomas glandulares possuem polissacarídeos neutros e compostos fenólicos. Além disso, foram observados laticíferos contendo gotículas lipídicas, alcalóides, proteínas e compostos fenólicos em diversas regiões da folha. As saponinas, características da família, foram observadas nos tricomas secretores e geralmente no mesofilo e nervura central. Os resultados obtidos fornecem evidências que justificam a investigação farmacológica dessas três espécies, bem como outras do gênero.
... These heteropolysaccharides are not dissimilar in composition to the hemicelluloses and pectins of the cell wall. Mucilage is present in several botanical orders (e.g., Caryophyllales, Fabales, Malvales, Asparagales, Brassicales) [1,2], often in the seed coat or the roots. In these tissues, it is relatively straight forward to identify and isolate the mucilage, as it exudes in the presence of water, forming a viscous layer that can help retain moisture, immobilize nutrients, create a beneficial rhizosphere, or counteract biotic attacks, among others [3]. ...
... While this facilitates the identification and isolation of the mucilage, the question of its role in planta becomes more complicated, as the large size of the mucilage hinders its mobility in the tissue. Among its proposed functions are drought [6] and frost [7] resistance and/or as a carbohydrate reserve [2]. ...
... Confidence interval calculated at 95% (n = 4).2 Recreated compositions, calculated from the monosaccharide content and yield for each fraction. ...
Opuntia joconostle is a semi-wild cactus cultivated for its fruit. However, the cladodes are often discarded, wasting the potentially useful mucilage in them. The mucilage is composed primarily of heteropolysaccharides, characterized by their molar mass distribution, monosaccharide composition, structural features (by vibrational spectroscopy, FT IR, and atomic force microscopy, AFM), and fermentability by known saccharolytic commensal members of the gut microbiota. After fractionation with ion exchange chromatography, four polysaccharides were found: one neutral (composed mainly of galactose, arabinose, and xylose) and three acidic, with a galacturonic acid content from 10 to 35%mol. Their average molar masses ranged from 1.8 × 10⁵ to 2.8 × 10⁵ g·mol⁻¹. Distinct structural features such as galactan, arabinan, xylan, and galacturonan motifs were present in the FT IR spectra. The intra- and intermolecular interactions of the polysaccharides, and their effect on the aggregation behavior, were shown by AFM. The composition and structural features of these polysaccharides were reflected in their prebiotic potential. Lactobacilli and Bifidobacteria were not able to utilize them, whereas members of Bacteroidetes showed utilization capacity. The obtained data suggest a high economic potential for this Opuntia species, with potential uses such as animal feed in arid areas, precise prebiotic, and symbiotic formulations, or as the carbon skeleton source in a green refinery. Our methodology can be used to evaluate the saccharides as the phenotype of interest, helping to guide the breeding strategy.
... The compartmentalization of the secretory epidermal cells is described in Lythraceae as well as in species belonging to other families (Bredenkamp and Van Wyk 1999;Seixas et al. 2021) and is linked to the formation of a wall-like septum (Gregory and Baas 1989). Our transmission electron microscopy analyses revealed that this septum consists of a true cellulosic cell wall. ...
... The subcellular sites of mucilage deposition detected here differ from those considered by Klider et al. (2020), who described the epidermal cells in the leaves of C. calophylla as containing mucilage on the periclinal external wall. Epidermal cells with mucilage have been reported in several plant groups (Solereder 1908;Metcalfe and Chalk 1950;Gregory and Baas 1989;Matthews and Endress 2006) as cells with a mucilaginous inner cell wall and distinct cytoplasm or entirely mucilaginous cells with an indistinct cytoplasm (Metcalfe and Chalk 1950;Napp-Zinn 1973). In the majority of cases, mucilage is deposited between the cell wall and the plasmalemma, and in exceptional cases, mucilage is considered to accumulate in vacuoles (Gregory and Baas 1989and references therein). ...
... The association with phenolic compounds is reported here for the first time in Cuphea species. This association, as seen in our results, is frequently described for mucilaginous secretory cells (Gregory and Baas 1989;Bredenkamp and Van Wyk 1999;Kumar et al. 2018;Seixas et al. 2021), because of the potential for tannins to absorb mucilage (Radlkofer 1875, apud Gregory and Baas 1989). Phenolic compounds play an important role as natural antioxidants, capturing excess reactive oxygen species, and deleterious ions (Bredenkamp and Van Wyk 1999;Kumar et al. 2018) and can also protect plants against UVB radiation (Windsor et al. 2000). ...
Cuphea calophylla Cham. & Schltdl. is a Lythraceae subshrub that occurs in different environmental conditions. The aerial portions of this plant have medicinal properties and are used for soap production. We assessed the structure, ultrastructure, and histochemistry of the secretory cells and tissues in C. calophylla leaves and stems to further understand its secretory system. Hydathodes with epithem, tracheary elements, and water pores occur at the leaf border and are here described for the first time for a Cuphea species. Glandular appendages occur in leaves and stems and are characterized by a wide basis and a narrower apical portion that exuded sticky material. Ontogenetical analysis showed that these appendages are glandular emergences; phenolic compounds, mucilage, and lipids were produced in their cells which exhibited Golgi bodies, vesicles, smooth endoplasmic reticulum, oil drops, and plastids. The epidermis of the leaf blade has bi-compartmentalized secretory cells divided by a cellulosic septum in their equatorial region. These cells contain phenolic compounds in the upper compartment and mucilage in the lower compartment. Our results shed light on the sites producing bioactive compounds in C. calophylla and expand the knowledge on the secretory system in Lythraceae, promoting a reclassification and an identification of new structures.
... Nos dias atuais, as pesquisas farmacológicas têm demonstrado interesse por extratos dessa planta no tratamento da diabetes melito (Sales et al., 2014) e, em tratamentos de infecções no estômago, pois estimula a produção de muco gástrico (Basting et al., 2014). (Jensen, 1962) para lipídeos totais, vermelho de rutênio para mucilagem ácida (Gregory & Baas, 1989), cloreto férrico para compostos fenólicos (Johansen, 1940 (Fisher, 1968) para identificar a presença de compostos de natureza protéica, com vermelho de rutênio para mucilagem ácida (Gregory & Baas, 1989), com o reagente PAS (Periodic Acid-Schiff´s) para polissacarídeos totais (Mcmanus, 1948) e com o cloreto férrico para compostos fenólicos (Johansen, 1940 ...
... Nos dias atuais, as pesquisas farmacológicas têm demonstrado interesse por extratos dessa planta no tratamento da diabetes melito (Sales et al., 2014) e, em tratamentos de infecções no estômago, pois estimula a produção de muco gástrico (Basting et al., 2014). (Jensen, 1962) para lipídeos totais, vermelho de rutênio para mucilagem ácida (Gregory & Baas, 1989), cloreto férrico para compostos fenólicos (Johansen, 1940 (Fisher, 1968) para identificar a presença de compostos de natureza protéica, com vermelho de rutênio para mucilagem ácida (Gregory & Baas, 1989), com o reagente PAS (Periodic Acid-Schiff´s) para polissacarídeos totais (Mcmanus, 1948) e com o cloreto férrico para compostos fenólicos (Johansen, 1940 ...
... Diferentes regiões dos sistemas subterrâneos de três indivíduos por espécie ainda frescos foram seccionadas no plano transversal em micrótomo de deslize com navalhas de aço descartáveis para identificação da estrutura anatômica e realização dos testes histoquímicos. Para os testes as seções foram submetidas aos seguintes corantes e reagentes: Sudan IV (Jensen, 1962) e Sudan Black B (Pearse, 1953) para lipídios totais; azul de metileno para mucilagem básica (Johansen, 1940); vermelho de rutênio para mucilagem ácida (Gregory & Baas, 1989); cloreto de zinco iodado para grãos de amido (Strasburger, 1899) e cloreto férrico para compostos fenólicos (Johansen, 1940). Seções controles foram realizadas conforme procedimento padrão para confirmação dos testes histoquímicos. ...
A área de Cerrado escolhida para o estudo está em regeneração na Estação Ecológica de Santa Bárbara, localizada no município de Águas de Santa Bárbara, SP. Nesta área o Pinus, que estava sob cultivo desde os anos 70, foi retirado em 2012 e, em 2014, foi realizada uma queimada. As espécies Eugenia dysenterica (Mart.) DC. e E. punicifolia (Kunth) DC. foram escolhidas devido ao elevado número de indivíduos que rebrotaram na área. O objetivo geral do projeto foi conduzir análises morfoanatômicas e químicas das estruturas relacionadas ao potencial de rebrotamento. Foram realizadas: a contagem das gemas subterrâneas nos primeiros 10 centímetros abaixo do nível do solo, as análises químicas das raízes e análises anatômicas na região terminal de ramos aéreos e no sistema subterrâneo. Nas duas espécies, além da gema apical dos ramos aéreos, nas três regiões nodais subsequentes, acima da gema axilar ocorre uma gema acessória. Em todas as gemas, observam-se estruturas de proteção, pois junto ao meristema apical caulinar (MAC) ocorrem coléteres e cristais. Além disso, o MAC é protegido por primórdios foliares com cavidades de óleo, muitos cristais e tricomas unicelulares não glandulares que possuem espessamento parietal em celulose e podem acumular compostos fenólicos. Nos sistemas subterrâneos, o número de gemas, localizadas preferencialmente nos primeiros cinco centímetros do solo, variou entre os três indivíduos da mesma espécie: E. dysenterica 162, 17 e 253, E. punicifolia 24, 40 e 109. Esta variação deveu-se ao grau de desenvolvimento das estruturas subterrâneas as quais certamente formaram-se antes do período da retirada do Pinus. O sistema subterrâneo das espécies é formado por um eixo lenhoso cuja porção superior é caulinar e emite vários ramos aéreos enquanto a porção inferior é constituída por uma raiz axial espessada que pode atingir até um metro de profundidade em E. dysenterica. Em E. punicifolia o sistema subterrâneo ocupa uma região mais superficial do solo e, assim como o caule, as raízes axial e adventícias são distribuídas num plano mais horizontal. O tecido de revestimento nas raízes de E. punicifolia e no caule e raízes de E. dysenterica, apresenta camadas alternadas de células de paredes suberizadas e de células com espessamentos parietais em pectina; no caule de E. punicifolia há esclereides que se alternam com as células suberizadas. Em E. punicifolia o espessamento resulta de divisões anticlinais e expansão tangencial das células do parênquima floemático. Há floema interno e parênquima medular nos caules subterrâneos de ambas as espécies. Compostos fenólicos e grãos de amido estão presentes nas células parenquimáticas de regiões mais espessadas dos caules e raízes. Os teores de carboidratos totais, hemicelulose, celulose e lignina não diferem significativamente nas duas espécies. No entanto, as concentrações de flavonoides totais e de compostos fenólicos totais foram superiores nas raízes de E. punicifolia. O grau de proteção das gemas aéreas, o elevado número de gemas e o acúmulo de compostos de reserva (amido) e de proteção (fenóis, flavonoides, lignina) nas estruturas subterrâneas podem ter favorecido o seu rebrotamento após a retirada do Pinus e a sua permanência das espécies na área.
... Sticky secretions, such as mucilage, are common in this region of plants and are generally associated with the presence of colleters, glandular trichomes, cavities, ducts, and idioblasts (Fahn 1979;1988;Appezzato-da-Glória & Carmello-Guerreiro 2022). Mucilage is mainly composed of acidic and/or neutral heteropolysaccharides, but it can also contain proteins and phenolic substances, forming colloidal solutions that become viscous upon contact with water (Gregory & Baas 1989;Roshchina & Roshchina 1993). Due to its hygroscopic nature, mucilage can perform various functions within the plant body, which include protecting developing structures and organs, retaining water, reducing transpiration, providing protection against herbivory, regulating seed germination, lubricating root tips, and serving as a strategy for capturing insects in carnivorous plants (Fahn 1979;Baas & Gregory 1985;Thomas 1991;Roshchina & Roshchina 1993;Paiva 2009;Mayer et al. 2011;Dalvi et al. 2014;Tresmondi et al. 2017;. ...
... Although exuded, mucilage too remains within intercellular spaces and substomatal chambers in B. curtii. Typically, internal mucilage is associated with storing water, protecting against high irradiance, herbivory defense upon mechanical injury, and acting as a carbohydrate reserve (Fahn 1979;Gregory & Baas 1989;Costa et al. 2021;Fortuna-Perez et al. 2021). Given mucilage's hygroscopic properties, its secretion by internal mucilage-producing structures is linked to mechanisms of water acquisition and allocation (Ballego-Campos et al. 2023), potentially adapting it to the characteristics of high-altitude fields, the natural habitat of B. curtii (Fortuna-Perez et al. 2021). ...
The stem apical meristems (SAM) are essential for the primary growth of plants and possess protective mechanisms to safeguard their fragile structures, including stipules and chemical secretions such as mucilage. This study examines Begonia curtii, focusing on the origin and composition of its protective sticky secretions. The research is set within the Atlantic Forest—a biodiversity hotspot—highlighting the plant's adaptive survival strategies. Samples of leaves and stipules at three stages of development were collected and analyzed using micromorphological, anatomical and histochemical techniques. The stem apices of B. curtii are covered by large, green stipules, which protect developing leaves and stipules with a mucilaginous secretion produced by trichomes and idioblasts present in both organs. Mucilage, originating from idioblasts present in the stipules, accumulates in the substomatal chambers and is released by the stomata, an atypical phenomena. The exudate from the hydathodes increases the volume of secretion to hydrate young organs and meristematic regions, protecting them from desiccation. The adult stipules remain attached to the stem, become dry, and without secretions, while the multiple epidermis and idioblasts, in adult leaves, store water and mucilage, respectively. The morphological and chemical differences between the leaves and stipules of B. curtii at different stages of development, reinforce both their physical and chemical protective roles in the face of biotic and abiotic factors typical of the Atlantic Forest’s rocky outcrops.
... The mucilage consists of high-molecular-weight acidic polysaccharides, which can be produced by secretory idioblasts, cavities, or ducts (Fahn 1988). It has been reported in leaves (West 1969;Metcalfe and Chalk 1950, 1979, 1983Napp-Zinn 1973;Metcalfe 1987;Mariani et al. 1988;Gregory and Baas 1989;Bakker and Gerritsen 1992b;Bakker and Baas 1993;Bredenkamp and Van Wyk 1999;Fortuna-Perez et al. 2021) and in flowers Igersheim 1997, 1999;Igersheim and Endress 1997;Merino Sutter et al. 2006;Matthews and Endress 2006;De Barros et al. 2017, De Barros et al. 2023) of different groups of plants. ...
... Scale bars: 20 μm: e, l; 50 μm: c, f, h, i, k 100 μm: a, b, d, g, j were found in many genera of Leguminosae such as Dimorphandra Schott (De Barros et al. 2017), Poiretia Vent., Zornia J.F.Gmel., Adesmia D.C., Nissolia Jacq., Pterocarpus Jacq. (Fortuna-Perez et al. 2012; 2021), Piptadenia Benth., Leucaena Benth., Anadenanthera Speg., Stryphnodendron Mart.(Pedersoli et al. 2023), as well as in more than 100 families of Angiosperms(Gregory and Baas 1989) within the orders Asterales, Austrobaileyales, Canellales, Caryophyllales, Celastrales, Dilleniales, Geraniales, Laurales, Magnoliales, Malpighiales, Malvales, Myrtales, Nymphaeales, Oxilidales, Rosales, Santalales, Sapindales, Vitales, Zygophyllales(Metcalfe and Chalk 1950;Bakker and Gerritsen 1992; Plachno et al. 2017;De Barros et al. 2023). ...
Mucilage cells are secretory structures associated with energy reserve and osmotic regulation, acting as a drought resistance mechanism. They are commonly found in legume species and can also contain phenolic compounds. Since they were previously identified in the sepals of one Mimosa species, the objective of the present study was to investigate the occurrence and location of mucilage and phenolic-secreting cells in the floral and leaf organs of species of this genus. We compare vegetative and reproductive organs, providing a detailed understanding of the distribution of these secretory structures throughout the plant body and proposing putative functions for them. Samples of foliar and floral organs of 13 species of Brazilian Mimosa were processed for anatomical analysis. Mucilage cells were found in the leaflet blade, petiole, rachis, rachilla, bract, sepal, and petal of all the species studied. In addition, M. caesalpiniifolia and M. sensitiva appeared to have mucilage cells also in the anther and ovary, and M. pudica in the filament and ovary. These cells occur throughout the entire epidermis of the organ or groups of cells, but may also occur in the mesophyll or in the cortical parenchyma. In most organs and species, mucilage cells usually also include phenolic compounds. Considering the close affinity between the production and accumulation of mucilage and phenolics, these two compounds may operate synergistically for plant protection and/or reproduction in Mimosa.
... Mucilaginous idioblasts were classified based on their shape and mode of mucilage deposition according to the nomenclature proposed by Matthews and Endress (2006), with adaptations if necessary. The following reagents were used for histochemical analysis: toluidine blue (modified from O'Brien et al. 1964) for the identification of mucilage; ruthenium red (Gregory and Baas 1989) for the identification of pectin and mucilage, and ferric chloride ( Johansen 1940) for the identification of non-structural phenolic compounds. As controls, reference material (Ventrella et al. 2013) was used for comparison in the histochemical tests, as well as unstained sections and sections not submitted to any test (blank). ...
... However, broader species sampling is necessary. The simultaneous presence of pectic (mucilage) and phenolic compounds in the same trichome cells in M. floridum is similar to the description of Orbenstein (apud Gregory and Baas 1989). This unique condition in M. floridum trichomes possibly represents a diagnostic character of the species. ...
Taxonomic and phylogenetic studies of Machaerium species have demonstrated overlapping morphological characters that delimit sections and/or clades, such as width, length, and overall shape of the leaflets and venation pattern. We conducted a comparative analysis of the morphoanatomical characters of Machaerium leaflets. We aimed to evaluate the usefulness of leaflet anatomical characters for Machaerium systematics, to assess whether these characters support the monophyly of the Lineata clade, to identify leaflet anatomical synapomorphies for the Lineata clade, and to evaluate secretory structures present in the leaflets regarding the type, location, distribution, and chemical nature of their exudates. Subterminal leaflets from 26 Machaerium species were examined by light and scanning electron microscopy. Phylogenetic and ancestral character state reconstruction analyses were performed for all members of the Lineata clade. Characters such as secondary venation pattern, type of stomata, presence of a subepidermal layer at the leaflet margin (hypodermis), trichome morphology, and the type and location of mucilaginous idioblasts are relevant at the species level. Secretory structures such as secretory-base trichomes, mucilaginous idioblasts, and phenolic idioblasts are confirmed for the species. Craspedodromous venation, papillose epidermis and marginal vascular bundles are shared by species of the Lineata clade and are considered a possible synapomorphy for the group. Our data reveal new useful characters for taxonomy of Machaerium species, reinforce the recognition of the monophyly of the Lineata clade, and support future studies focused on the systematics of the genus.
... Meanwhile, conceptual differences caused by structural variability in the inflorescences of Malvaceae, as well as their diverse secretory structures on the reproductive axis, provide an additional rationale for the present study. In that context, we note that such diversity includes extrafloral and floral nectaries, as well as secretory trichomes, idioblasts, channels, and secretory cavities (Gregory and Baas 1989;Sawidis 1998;Scott and Bystrom 1970). Moreover, ant foraging is common in extrafloral and floral nectaries (Pacini and Nicolson 2007), and since this behavior in flowers with articulated axes and potential secretory structures remains poorly studied, we herein describe the development of secretory structures related to ant foraging, along with position details and histochemical characterization. ...
... Section 0.5 μm thick were adhered to slides with a heating plate. Then, the following tests were carried out: ruthenium red for acidic polysaccharides/mucilage (Gregory and Baas 1989); Periodic acid-Schiff (PAS) for neutral polysaccharides (McManus 1948); Lugol's iodine for starch (Johansen 1940); Sudan III for lipids (Johansen 1940); Wagner's reagent for alkaloids (Furr and Mahlberg 1981); and Nadi's reagent for essential oils and oleoresins (David and Carde 1964). ...
In the Malveae tribe (Malvaceae), the axis supporting the flower has a joint at the upper third. This axis can be considered as an articulated pedicel, peduncle, peduncle-pedicel, or anthopodium. Such disparity in terminology reveals a duality in interpretation since this structure is classified as part of the inflorescence or part of the flower. In an effort to reach a consensus, this study aims to evaluate axes supporting the flowers of species from the Malveae tribe through ontogenetic, morphological, and histochemical analyses, using light microscopy and scanning electron microscopy. Ontogenetic analyses indicated that the axis supporting the flower is an articulated pedicel, which is divided into proximal and distal parts owing to the presence of the constriction (joint). Simultaneously, the articulated pedicel arises from the floral meristem, along with the establishment of the calyx and androecium. As development progresses, we observed frequent abscissions of the floral bud, along with the distal portion of the pedicel, at the joint. After this, the remaining proximal portion of the pedicel becomes secretory, as an extrafloral nectary, often foraged by ants of the genus Wasmannia. Thus, this ontogenetic analysis of the articulated pedicel helps in understanding its functionality and morphological variability, highlighting the importance of standardized terminology since it would lead to conceptual clarity in different studies. Additionally, this study, for the first time, reveals the presence of extrafloral nectaries on articulated pedicels in Malveae, a previously undocumented feature in Malveae and Malvaceae.
... To detect wall compounds in GTS cells, the following histochemical tests were performed -in freehand sections-: Periodic acid reaction -Schiff reagent /PAS (McManus 1948) for general characterization of polysaccharides, linked to the presence from the vic-glycol group (-CHOH-CHOH) or related groups (does not react with cellulose and callose); ruthenium red for the detection of pectins (Johansen 1940) and mucilages (Gregory & Baas 1989); alcian blue and neutral red (Ruzin 1999) for the presence of acid mucopolysaccharides; alcian blue and PAS (Ruzin 1999) to detect acid mucopolysaccharides and general polysaccharides; acid phloroglucine (Johansen 1940) to detect lignin; Sudan III (Johansen 1940) to stain fats, and Lugol to verify amyloplasts in the cytoplasm (Johansen 1940). ...
... Histochemical tests on cross-sections of the stem of P. vaginatum showing the ground tissue of the stele (GTS) -a. lugol, showing amyloplasts in the cytoplasm (dark blue); b. acid phloroglucine, detecting lignin (orange) in sclerenchyma cells and the absence of lignin in GTS (*); c. alcian blue and neutral red (contrasting) with negative reaction to acidic mucopolysaccharides; d. alcinane blue/PAS with negative reaction to acidic mucopolysaccharides and positive to general polysaccharides (magenta); e. periodic acid reaction -Schiff reagent (PAS) with positive reaction to general polysaccharides (magenta); f. ruthenium red(Johansen 1940), detecting pectin in the cell wall (intense pink to red); g. ruthenium red solution(Gregory & Baas 1989) with negative reaction to mucilages; h. tannic acid/ferric chloride with negative reaction to mucilage. ...
Paspalum vaginatumis a halophyte plant found along coastal plains, which presents cells with atypically thickened walls in the ground tissue of the stem stele (GTS). The tolerance of this species to high salinity and water stress led us to investigate whether the thickened walls could be related to adaptation to the coastal environment. Thus, we sought to characterize the cell walls that make up the GTS ofP. vaginatum, describe the tissue, and verify the influence of the water resource on the thickening of the walls and a possible function related to the reserve of substances. For this, analyses were carried out using light microscopy, transmission electronic microscopy, and histochemical tests. The samples were collected in the field during low and high rainfall periods.Paspalum vaginatumGTS cells have pectic-cellulosic primary walls. In most basal internodes, these cells presented thickened walls formed in two to three layers. Statistical analysis demonstrated that the level of precipitation is directly related to cell wall thickening. The data suggest the storage and mobilization of substances through the cell wall of the specialized parenchyma.
... Many functions have been attributed to mucilage cells (carbohydrate and water storage, transpiration reduction, protection against radiation, and protection against herbivores), but experimental evidence is lacking, and since the review by Gregory and Baas [124], their functions remain mostly unexplained. Oil cells occur in many Lauraceae woods, including Nectandra grandis, in some species of Ocotea spp., and in Phoebe porosa. ...
... Many functions have been attributed to mucilage cells (carbohydrate and water storage, transpiration reduction, protection against radiation, and protection against herbivores), but experimental evidence is lacking, and since the review by Gregory and Baas [124], their functions remain mostly unexplained. ...
Hardwoods are complex heterogeneous and orthotropic structures that have evolved to the present day, adapting to successive climate episodes to prosper on Earth. Attributing a specific functionality to individual hardwood elements is difficult because of their interconnection in this heterogeneous three-dimensional network. However, tree physiology research is helping to enhance knowledge in this field. This work is a short review of the possible functionalities of hardwood elements, in some cases supported by experimentation and in others by comparative anatomy. It is intended for students or researchers starting out in the world of hardwood anatomy to aid their understanding of the functionality of hardwood elements.
... The distribution of phenolic idioblasts in all plant organs of H. lupulus, primarily within the subepidermis of leaves and the stem parenchyma, along with the variety of morphological shapes, is also reported in other plant groups, such as ferns, gymnosperms, and angiosperms, including Apocynaceae, Euphorbiaceae, Fabaceae, Pinaceae, Primulaceae and Pteridaceae [75][76][77][78][79][80][81][82][83]. In closely related families to Cannabaceae, phenolic idioblasts can also be found in Ulmaceae, Moraceae, and Urticaceae [76]. ...
... The distribution of phenolic idioblasts in all plant organs of H. lupulus, primarily within the subepidermis of leaves and the stem parenchyma, along with the variety of morphological shapes, is also reported in other plant groups, such as ferns, gymnosperms, and angiosperms, including Apocynaceae, Euphorbiaceae, Fabaceae, Pinaceae, Primulaceae and Pteridaceae [75][76][77][78][79][80][81][82][83]. In closely related families to Cannabaceae, phenolic idioblasts can also be found in Ulmaceae, Moraceae, and Urticaceae [76]. The presence of phenolic idioblasts in all plant organs of H. lupulus, and a wide range of secondary metabolites in their secretion, indicate a probable important role in plant defense still not fully comprehended. ...
Cannabaceae species garner attention in plant research due to their diverse secretory structures and pharmacological potential associated with the production of secondary metabolites. This study aims to update our understanding of the secretory system in Hops (Humulus lupulus L.), an economically important species especially known for its usage in beer production. For that, stems, leaves, roots, and inflorescences were collected and processed for external morphology, anatomical, histochemical, ultrastructural and cytochemical analyses of the secretory sites. Our findings reveal three types of secretory structures comprising the secretory machinery of Hops: laticifer, phenolic idioblasts and glandular trichomes. The laticifer system is articulated, anastomosing and unbranched, traversing all plant organs, except the roots. Phenolic idioblasts are widely dispersed throughout the leaves, roots and floral parts of the species. Glandular trichomes appear as two distinct morphological types: capitate (spherical head) and peltate (radial head) and are found mainly in foliar and floral parts. The often-mixed chemical composition in the secretory sites serves to shield the plant from excessive UVB radiation, elevated temperatures, and damage inflicted by herbivorous animals or pathogenic microorganisms. Besides the exudate from peltate glandular trichomes (lupulin glands), latex and idioblast content are also likely contributors to the pharmacological properties of different Hop varieties, given their extensive presence in the plant body.
... More rarely they are to be found in the leaf abaxial epidermis, the mesophyll, the midrib cortex and the petiole. These results are consistent with a previous study (Gregory and Baas 1989). It is worth emphasizing that the exclusive location of mucilage cells in the palisade parenchyma is being described here for the first time for Lauraceae. ...
... Thus, the presence of mucilage in the aerial organs could be interpreted as an adaptation to a harsh environment associated with water retention and ionic balance, prevention of desiccation and favoring organ growth and also as a protective mechanism against herbivory and pathogens (Lusa et al. 2014). Mucilage may also be important as a reserve carbohydrate for use in lean times of the year (Gregory and Baas 1989). Lastly, it is worth considering that (based on our own observation) mucilage idioblasts can release their contents onto the leaf surface, thus changing the water-permeability properties of the leaves (Paiva et al. 2022). ...
This study compares oil and mucilage idioblasts occurring together in the vegetative organs of Ocotea pulchella, a Lauraceae species. Our focus is specifically on the ontogeny and developmental cytology of these secretory cells. Both types of idioblasts originate from solitary cells located in the fundamental meristem, underlying the protodermis. The growth of both types of idioblasts is asynchronous, with the oil idioblasts developing first, but their initiation is restricted to the early stages of organ development. Mucilaginous idioblasts occur exclusively in the palisade parenchyma, while oil idioblasts are scattered throughout the mesophyll, midrib, and petiole of the leaves. The lamellar secretion of mucilage idioblasts is mostly made up of polysaccharides, while the secretion of oil idioblasts is made up of terpenes and lipids. Cupule occurred only in the oil idioblasts, while suberized layers occurred in both types of cells. We found that immature oil idioblasts that are close to each other fuse; mature mucilage idioblasts have labyrinthine walls arranged in a reticulate pattern; the cells close to the oil idioblasts have a pectin protective layer; and the oil idioblasts have a sheath of phenolic cells. In contrast to previous reports, the two types of secretory idioblasts were recognized during the early stages of their development. The results emphasize the importance of combining optical and electron microscopy methods to observe the ontogenetic, histochemical and ultrastructural changes that occur during the development of the secretory idioblasts. This can help us understand how secreting cells store their secretions and how their walls become specialized.
... Nevertheless, mucilage exudation through the stomata would not explain any significative contribution of these structures to the secretion observed on the adaxial side. Mucilage retention in the interior of the plant body, either inside the cells or in internal spaces, is not uncommon among plants (Fahn 1979;Gregory and Baas 1989;Barros et al. 2023). Internal mucilage is usually associated with water storage, protection from high irradiance, protection against herbivory (upon mechanical damage) and carbohydrate storage (Fahn 1979;Gregory and Baas 1989;Costa et al. 2021;Fortuna-Perez et al. 2021). ...
... Mucilage retention in the interior of the plant body, either inside the cells or in internal spaces, is not uncommon among plants (Fahn 1979;Gregory and Baas 1989;Barros et al. 2023). Internal mucilage is usually associated with water storage, protection from high irradiance, protection against herbivory (upon mechanical damage) and carbohydrate storage (Fahn 1979;Gregory and Baas 1989;Costa et al. 2021;Fortuna-Perez et al. 2021). Due to the hygroscopic capacities of mucilage, the mucilaginous tissue could function similarly to the water-storage tissue, retaining water and avoiding desiccation. ...
Bromeliaceae display many water-use strategies, from leaf impounding tanks to CAM photosynthesis and absorbing trichomes. Recent studies show that trichomes in inflorescences of bromeliads can exude viscous secretions, protecting against various stresses, including excessive water loss. In light of this, and considering the knowledge gap regarding inflorescence trichomes in bromeliads, we aimed to investigate the presence, source, and chemical nature of inflorescence secretions in species of the Tillandsioideae (Bromeliaceae) and to describe the anatomy of their floral bracts focusing on trichome structure and position.We conducted a prospection of secretory activity and anatomy in floral bracts in 52 species of Tillandsioideae and one early-divergent Bromeliaceae species. We used histochemical tests to investigate the presence and nature of secretion combined with standard light microscopy methods. Secretion appears in all studied species of tribe Vrieseeae, in Guzmania species, Wallisia cyanea, Tillandsia streptopylla (Tillandsieae), and Catopsis morreniana (Catopsideae). It is absent in Vriesea guttata (Vrieseeae), Racinaea crispa, and various Tillandsia species (Tillandsieae). Secretion is produced by peltate trichomes on the adaxial surface of young bracts and comprises hydrophilic and lipophilic substances. Bract anatomy revealed an internal mucilage-secreting tissue with wide distribution within subtribe Vrieseinae. Our results point to a broad occurrence of secretion associated with bracteal scales in inflorescences of Tillandsioideae. Secretory function is strongly related to trichomes of the adaxial surface, whereas the indumentum of the abaxial side is lacking or likely associated with water absorption; the latter case is especially related to small, xeric plants. Exudates might engage in colleter-like roles, protecting against desiccation, high-radiation, and herbivores. Directions for future research are presented.
... The presence of mucilage is a condition shared by several groups of plants (Gregory and Baas 1989). Thus, we also reviewed here the distribution of mucilage cells in vegetative and reproductive organs of species of the Rosales order (Table 2, Supplementary material). ...
... The Leguminosae family belongs to the Fabales order, a sister group of the clade composed of Rosales, Fagales, and Cucurbitales (APG IV 2016). In this family, mucilage cells also have a wide distribution in the stem and leaves, mainly in the epidermis (Gregory and Baas 1989;Matthews and Endress 2006;Fortuna-Perez et al. 2021), whereas few studies about mucilage cells in flowers have been reported (Matthews and Endress 2006;De Barros et al. 2017). On the other hand, mucilagesecreting cavities were also reported for species of this family (Fortuna-Perez et al. 2021). ...
The presence of mucilage cells in plants, studied mainly in vegetative organs, is a condition shared by several taxonomic groups and aspects related to their diversity have been discussed with systematic purposes. This study explores the flower distribution and classification of mucilage cells in Rosales species, with inferences about flower functions. Floral buds from fifty-seven species representing seven of nine families recognized in the Rosales were sampled and processed for light and transmission electron microscopy. Mucilage cells were found in about 40% of the studied species of Cannabaceae, Rhamnaceae, Ulmaceae, and Urticaceae families, whereas no floral mucilage cells were found in species of Elaeagnaceae, Moraceae, and Rosaceae. Mucilage cells were found in the epidermis and internal tissues of many organs of different floral morph types. There is a great diversity of forms of presentation of mucilage in cells, from smaller individualized single cells to very bulky cells and to completely filled mucilage reservoirs. In some cases, cells with mucilage apparently in the cell wall and others with mucilage in the vacuole seem to occur side by side. This diversity challenges the existing classifications of mucilage cells and reinforces the importance of ontogenetic and ultrastructural studies following the path of mucilage in cells in order to propose a more natural classification and to elucidate the evolution of mucilage cells in plants.
... This method stains acidic mucilages, pectins [20,21], and nucleic acids magenta or red (Fig. 2a). ...
... The procedure and control for this observation in fluorescence are the same as previously described for this stain. 21. In the case of paraffin and PEG, the embedding medium should be removed prior observation. ...
Histochemical analysis is essential for the study of plant secretory structures whose classification is based, at least partially, on the composition of their secretion. As each gland may produce one or more types of substances, a correct analysis of its secretion should be done using various histochemical tests to detect metabolites of different chemical classes. Here I describe some of the most used methods to detect carbohydrates, proteins, lipids, phenolic compounds, and alkaloids in the secretory structures.
... Subsequently, the obtained material was stained with 0.05% toluidine blue in phosphate buffer and citric acid with a pH of 4.52 (Sakai 1973). Histochemical tests were performed using ferric chloride for total phenolic compounds (Johansen 1940), ruthenium red for detection of acid mucilage (Gregory and Baas 1989), Sudan IV (Jensen 1962), and Sudan Black B (Gersh 1953) for total lipids and Lugol (Johansen 1940) for starch grains. Sections unstained or stained with Calcofluor White were analyzed using a DAPI autofluorescence filter. ...
This study aimed to investigate the potential of Silicon (SiO2NPs and Na2SiO3) to mitigate Hg absorption, accumulation, and toxicity in transgenic soybean plants. By analyzing Hg speciation, total Hg content, physiological characteristics, anatomical structures, and the homeostasis of macro (P, S, Ca, K, and Mg) and micro (Cu, Fe, Mn, Zn) nutrients, the impact of Si against Hg-induced stress was assessed. Plants were cultivated under six treatments: water, SiO2NPs, Na2SiO3, Na2SiO3 + HgCl2, SiO2NPs + HgCl2, and HgCl2. The addition of silicon to the soil, both in the form of nanoparticles and in its soluble form, did not negatively impact plant development. SiO2 NPs reduced Hg concentration in roots by 17% (RR) and 29% (INTACTA) and Na2SiO3 by 15% and 37%. In leaves, Hg reductions were 25% with SiO2NPs and 22% with Na2SiO3 for RR variety, while INTACTA showed decreases of 14% and 34%. Only Hg(II) species were found, indicating no Hg methylation in soil or plants. PCA revealed that Hg, alone or with Si, altered nutrient absorption. Morphological analyses showed that SiO2NPs and Na2SiO3 reduced Hg toxicity at the cellular level, highlighting their potential to mitigate heavy metal contamination in crops.
... For the general characterisation of the exudate, the following histochemical tests were carried out only in the samples fixed in FAA and FNT: ferric chloride for total phenolic compounds (Johansen 1940); hydrochloric vanillin for tannins (Mace and Howell 1974); Sudan black for total lipids (Pearse 1960); ruthenium red for acid mucilage (Gregory and Baas 1989); Wagner reagent for alkaloids (Furr and Mahlberg 1981); xylidine ponceau for proteins (Vidal 1970); and PAS for total polysaccharides (McManus 1948). Standard control procedures were carried out simultaneously as required for each test. ...
... They were mounted in glycerol, and observations were made. A color spectrum ranging from pink to red indicated a positive reaction (Gregory and Baas, 1989;Demarco, 2017). ...
... c, d, Psidium grandifolium plants (arrows) observed in the regenerating area, where it is evident that these individuals were fully exposed to sunlight. black B (Pearse 1953) for total lipids, ruthenium red for acidic mucilage (Gregory and Baas 1989), zinc chloride iodine (Strasburguer 1913) and Lugol's solution (Johansen 1940) for starch grains, and ferric chloride for phenolic compounds (Johansen 1940). Sections were also subjected to Nile red fluorochromes for lipids (Greenspan et al. 1985) under a Leica I3 filter (excitation: BP 400-490 nm; emission: 530-575 nm); for autofluorescence of phenolic compounds, unstained sections were analyzed under a Leica L5 filter (excitation: BP 460-500 nm; emission: 512-542 nm; Cardoso-Gustavson et al. 2018). ...
Disturbance-prone ecosystems, such as the world’s savannas, are predominantly composed of plant species thatdeveloped several morphoanatomical adaptations that grant them high resilience to natural and anthropogenicdisturbances. An essential adaptation is the protection of aboveground buds, which play a crucial role in the forma-tion of new photosynthetic organs and enable colonization of these areas. Our study aims to assess whether the pro-tection mechanisms of aboveground buds of Psidium grandifolium Mart. ex DC. are affected by environmentalstressors in two distinct environments: a natural Cerrado area and a Cerrado area under regeneration after decadesof use as a pine plantation. Aerial branches were collected from both environments and processed using standardmethodologies for light, fluorescence, and scanning microscopy analyses. Our observations revealed the presenceof hairy leaf primordia with phenolic compounds and secretory cavities covering the buds in both areas. Additionally,crystals, brachysclereids, and colleters were consistently found near the buds in all analyzed nodes. In the plants fromthe regenerating area, the buds increased hairiness and deposition of epicuticular waxes on both surfaces of expandedleaves as a response to the intense sunlight exposure. Our findings highlight that belowground resprouting speciesalso invest in aboveground bud protection and morphological adaptations to enhance their adaptability and resil-ience in disturbance-prone ecosystems, such as the Cerrado.
... Histochemical analyses were performed from BNF fixed samples. Hand free sections were tested using the following reagents: ferrous sulphate in neutral formalin and metachromasia with toluidine blue were used to reveal phenolic compounds; NADI's reagent (David and Carde 1964) for oil-resins; Coomassie blue (Fisher 1968) and Xylidine Ponceau (Clark 1981) for proteins; Ruthenium red (Gregory and Baas 1989) for acid mucilage and/ or pectins; Schiff Reagent and periodic acid (McManus 1948) for total polysaccharides; and Fehling's reagent for reducing sugars (Purvis et al. 1964). The presence of glucose in bracteole and sepal gland exudate was tested by urinalysis tape (DFI CO Ltd. ...
The presence of diverse secretory structures is emblematic of Malpighiaceae, such as the presence of nectaries secreting sugary nectar and elaiophores secreting oil-resin. Recent studies have demonstrated the morphoanatomical and chemical similarities between these two glands but, in general, there are no comparative morphoanatomical analysis on inflorescence glands. The Galphimioid clade is an excellent model for studies on the presence of secretory tissue due to the variation found among genera with regards to both their bracteole and sepal glands. In this work, we describe the morphoanatomy and histochemistry of bracteole and sepal glands in species of Lophanthera. Furthermore, we update the species geographic distribution map and explore the morphological diversity of both sepal and bracteole glands in the Neotropical Galphimioid clade. Samples collected in the field and obtained from herbarium specimens were processed under usual anatomical techniques. The bracteole glands varied in surface shape, while the calyx glands varied mainly in size. Anatomically, both types of gland have palisade secretory epidermis and vascularized secretory parenchyma. The presence of proteins, polysaccharides, phenolic compounds, and reducing sugar was detected by histochemical tests. The bracteole glands of the inflorescences in Lophanthera were characterized as nectaries that produce a hydrophilic secretion. The sepal glands were identified as elaiophores by the presence of lipids and fixed oil. The results reinforce the functional role of floral nectaries of bracteoles and elaiophores of sepals according to the nature of the secretion, its potential visitors, and reported literature. The morphofunctional diversity reported in this work is unprecedented for the clade and is fundamental in the adaptive evolution of the family.
... The sections obtained were stained with 0.05% (v/v) toluidine blue in phosphate buffer and citric acid with a pH of 4.52 21 for structural analysis. For the detection of different chemical groups, the sections were subjected to the following dyes and reagents: Sudan IV 22 and Sudan Black B 23 for total lipids, ruthenium red for acid mucilage, 24 Lugol for starch grains, 25 and ferric chloride for phenolic compounds. 25 Sections stained with Calcofluor White 25 and unstained were analyzed using a DAPI autofluorescence filter (example: BP 350−365 nm, in 445−450 nm). ...
This study investigated the effect of AgNPs and AgNO3, at concentrations equivalent, on the production of primary and secondary metabolites on transgenic soybean plants through an NMR-based metabolomics. The plants were cultivated in a germination chamber following three different treatments: T0 (addition of water), T1 (addition of AgNPs), and T2 (addition of AgNO3). Physiological characteristics, anatomical analyses through microscopic structures, and metabolic profile studies were carried out to establish the effect of abiotic stress on these parameters in soybean plants. Analysis of the ¹H NMR spectra revealed the presence of amino acids, organic acids, sugars, and polyphenols. The metabolic profiles of plants with AgNP and AgNO3 were qualitatively similar to the metabolic profile of the control group, suggesting that the application of silver does not affect secondary metabolites. From the PCA, it was possible to differentiate the three treatments applied, mainly based on the content of fatty acids, pinitol, choline, and betaine.
... The main chemical classes of compounds in the secretion were detected using the following histochemical tests: Sudan black B and Sudan IV for lipids, 54 Nile blue for acidic and neutral lipids, 55 copper acetate and rubeanic acid for fatty acids, 56,57 ferric chloride for phenolic compounds, 51 Aniline blue black for proteins, 58 periodic acid-Schiff's (PAS) reaction for carbohydrates, 59 Ruthenium red for acidic mucilage 60 and tannic acid and ferric chloride for mucilage. 61 Autofluorescence under UV was also used for detection of phenolic compounds. ...
Nuptial glands are very diverse and associated with different pollination mechanisms. The greater the specifici-ty in the pollen transfer mechanism from anther to stigma, the greater the morphological elaboration of flowers and functional complexity of the nuptial glands. In Apocynaceae, pollination mechanisms reached an extreme specificity, a fact that was only possible due to an extreme morphological synorganization and a profusion of floral glands. Although these glands are of different types, the vast majority have secretory cells only in the epi-dermis. In general, these epidermal cells produce many different compounds at the same time, and previous studies have demonstrated that in the style head, the functional complexity of epidermis has become even greater. Four types of style head are found in the family, which have different degrees of functional complexity in relation to the secretion produced and pollen dispersal mechanism. The secretion is fluid in types I, II and III, and the pollen is dispersed and adhered to the pollinator by the secretion produced by the style head. In type IV, the secretion hardens and acquires a specific shape, moulded by the spatial constraints of the adjacent floral organs. This evolutionary alteration is accompanied by changes in the structure and arrangement of the secre-tory cells, as well as in pollen aggregation and position of stigma. Histochemical analysis has shown that the secretion is mixed and highly complex, especially in the style head type IV, where the secretion, called translator , is formed by a rigid central portion, which adheres to the pollinator, and two caudicles that attach to two pollinia. The translator has a distinct composition in its different parts. Further studies are needed to answer the new questions that have arisen from the discovery of this highly functional complexity of the secretory tissue.
... À microscopia óptica, a mucilagem permanece hialina ou forma estrias típicas deste material 61,62 . É característico nas Malvales a presença de células e, até mesmo, cavidades contendo predominantemente mucilagem 62,63,64 . Na realidade, já foi demonstrado que numerosas estruturas participam da secreção de mucilagem: idioblastos, cavidades, ductos, superfícies epidérmicas em muitas espécies e inclusive nas Sterculiaceae ocorrem cavidades lisígenas preenchidas com mucilagem na raiz, caule, flores e folhas 52,65,66 . ...
Os estudos sobre as reservas das sementes do gênero Theobroma referem-se sobretudo de T. cacao L, até hoje a única fonte da matéria prima do chocolate. Essas pesquisas abordaram as mudanças bioquímicas ocorridas na semente durante a fermentação, secagem, torração ou seja das etapas de produção do chocolate. Mais recentes são os trabalhos com sementes de T. grandiflorum (cupuaçu), utilizadas na elaboração do cupulate, produto com algumas características do chocolate. Por esse motivo, os especialistas em Theobroma estão ampliando as análises com as reservas das sementes para as espécies T. grandiflorum (Willd. Ex Spreng.) Schum, T. subincanum Mart, T. obovatum Bern., T. bicolor H. & B., T. microcarpum Mart e T. speciosum Mart. Como o interesse é voltado à possibilidade de ampliar as fontes de chocolate, as características estudadas nesta revisão são comparadas com T. cacao L. O mesofilo cotiledonar é semelhante em todas as espécies aqui estudadas devido a predominância de reserva lipídica e protéica. As células do cotilédone imaturo demonstram capacidade para sintetizar todas as reservas; na maturidade demonstram predominância de reservas lipídicas, protéicas ou de mucilagem ou de polifenóis.
... In general xerophytic ferns adapted to dry habitats present microphylly (reduction and high division of their leaf surface), thick cuticles, epidermal appendages, a reduction in the stoma size and density, vascular bundles surrounded by sclereids, suberized endodermis, sclerenchyma in the cortex of exposed roots and a predominance of palisade parenchyma in the mesophyll (Pandé 1935;Hevly 1963;Schneider 1997;Tejero-Diez et al. 2009Leroux et al. 2011;Hernández et al. 2011Hernández et al. , 2013. The leaf tissues are rich in phenolic compounds which act as antioxidants, as protection against ultraviolet light radiation, and as chemical defense against the attack of herbivores, bacteria and fungi (Orhan et al. 2010;Negri et al. 2014;Hasanuzzaman 2020), and in mucilaginous polysaccharides which may work as gels that can absorb and retain water (Gregory & Baas 1989;Ghanem et al. 2010). ...
... For anatomical analyses, some sections were clarified in a commercial solution of 20% sodium hypochlorite (v/v) diluted to 2.5% (w/w) and subsequently rinsed in distilled water, stained with safranin and Alcian blue (Bukatsch 1972) and mounted in glycerol 50% (v/v, glycerol/alcohol). In other sections, the following reagents and dyes were applied to characterize and locate the reserve substances: periodic acid-Schiff reagent (PAS) to detect general polysaccharides (McManus 1948), zincchloride iodide for starch grains (Strasburger 1913), xylidine ponceau for proteins detection (O'Brien and McCully 1981), Sudan IV (Jensen 1962) or Sudan black B (Pearse 1985) for total lipids detection, ferric chloride for phenolic compounds (Johansen 1940), ruthenium red for pectin and mucilage (Gregory and Baas 1989). The images were digitally captured with a Leica DFC310 Fx camera coupled to a Leica microscope (Leica, Wetzlar, Germany). ...
The presence of belowground organs with buds and carbohydrate storage is typical of perennial plants in fire-prone ecosystems. The bud-bearing storage organs allow regeneration after fire, and they may lose their regeneration capacity if the disturbance is excluded, because of the depletion in the bud bank. We assessed the morphology, anatomy, and storage of carbohydrates in the belowground organs of eight perennial species from open savannas and analyzed their bud banks at different fire frequencies (annual, biennial, and exclusion). Xylopodium was found in all the study species as bud-bearing organ, associated with proliferated storage parenchyma tissue, often in the tuberous roots. We found that bud bank size varied according to different fire frequencies for only half of the studied species (most forbs), and a tendency for lower bud bank sizes in fire-excluded areas was found for all shrub species. Our study highlights the significance of bud-bearing storage organs, particularly xylopodium, and that the species-specific responses of bud bank size to different fire frequencies underscore the need to consider individual plant strategies when analysing fire effects, emphasizing the critical role of belowground organs in sustaining these ecosystems.
... The main chemical classes of the constituents of nectar were investigated using the following histochemical tests in the embedded nectaries: periodic acid-Schiff's (PAS) reaction for carbohydrates [65], ruthenium red for acidic mucilage [66], tannic acid and ferric chloride for mucilage [67], Lugol's reagent for starch [62], aniline blue black for proteins [68], Sudan black B and Sudan IV for lipids [69], Nile blue for acidic and neutral lipids [70], copper acetate and rubeanic acid for fatty acids [71,72], ferric chloride and fixation in ferrous sulphate-formalin for phenolic compounds [62], and Dragendorff's [73] and Wagner's [74] reagents for alkaloids. Standard control procedures were carried out according to Demarco [23]. ...
Sapindales is a large order with a great diversity of nectaries; however, to date, there is no information about extrafloral nectaries (EFN) in Sapindaceae, except recent topological and morphological data, which indicate an unexpected structural novelty for the family. Therefore, the goal of this study was to describe the EFN in Sapindaceae for the first time and to investigate its structure and nectar composition. Shoots and young leaves of Urvillea ulmacea were fixed for structural analyses of the nectaries using light and scanning electron microscopy. For nectar composition investigation, GC-MS and HPLC were used, in addition to histochemical tests. Nectaries of Urvillea are circular and sunken, corresponding to ocelli. They are composed of a multiple-secretory epidermis located on a layer of transfer cells, vascularized by phloem and xylem. Nectar is composed of sucrose, fructose, xylitol and glucose, in addition to amino acids, lipids and phenolic compounds. Many ants were observed gathering nectar from young leaves. These EFNs have an unprecedented structure in the family and also differ from the floral nectaries of Sapindaceae, which are composed of secretory parenchyma and release nectar through stomata. The ants observed seem to protect the plant against herbivores, and in this way, the nectar increases the defence of vegetative organs synergistically with latex.
... Samples were dehydrated in an ethylic series (70-100% ethanol) and then infiltrated in plastic resin (Leica Historesin®), sectioned transversely and longitudinally in a rotary microtome (Leica®) with thickness of 5-7 µm, and stained with 0.05% toluidine blue in citrate buffer at pH 4.5 [76]. To identify different chemical groups, leaf sections were submitted to different reagents: Sudan IV and Sudan Black B for lipids [49,70]; red ruthenium for acid mucilage [41]; zinc chloride for starch grains [85] and ferric chloride for phenolic compounds [50]. Samples were submitted to Nile red fluorochromes for lipids [40], over filter (ex: BP 400-490 nm; em: 530-575 nm), and for auto-fluorescence of phenolic compounds, unstained sections were analysed under filter (ex: BP 460-500 nm; em: 512-542 nm) [17]. ...
This study is the first to investigate the speciation and spatial distribution patterns of manganese (Mn) accumulated at elevated concentrations in Eucalyptus leaves by X-ray fluorescence (µ-XRF) and absorption near-edge spectroscopy (µ-XANES). Eucalyptus tereticornis is a tree species with great economic value and potential to accumulate and tolerate high Mn despite not being considered a hyperaccumulator. Seedlings grown under glasshouse conditions were irrigated with two Mn treatments: control Mn (9 µM) and high Mn solution (1000 µM). Biomass and total nutrient concentrations were assessed in roots, stems and leaves. Manganese, calcium (Ca) and potassium (K) spatial patterns were imaged by µ-SXRF in different foliar structures, and Mn speciation was conducted in these compartments by µ-XANES. Under high supply, Mn was distributed across the leaf mesophyll suggesting vacuolar sequestration in these cells. High Mn decreased cytosolic Ca by almost 50% in mesophyll cells, but K remained unaltered. Speciation suggests that a majority of the Mn fraction was complexed by organic ligands modeled as Mn-bound malate and citrate, instead of as free aqueous Mn2+ or oxidised forms. These two detoxification mechanisms: effective vacuolar sequestration and organic acid complexation, may be responsible for the impressively high Mn tolerance found in eucalypts.
... Additionally, not all rehydrated materials resulted in suitable samples for anatomical/histochemical analyses, aside from the reduced number of flowers in this study. To detect the main classes of compounds in the glands' exudate, we used copper acetate/rubeanic acid for fatty acids (Ganter and Jolles 1969), PAS reaction for total polysaccharides (McManus 1948), and ruthenium red or tannic acid and ferric chloride for mucilage (Gregory and Baas 1989;Pizzolato 1977). The digital images were acquired with an Olympus BX53 compound microscope equipped with an Olympus I-Colour 5 digital camera and Image Pro Express 6.3 software. ...
Connective glands are important morphological characters for the taxonomy of some genera of Malpighiaceae, with few recent studies having just elucidated these glands' anatomical and ecological functions. In order to test the systematic relevance of connective glands to the currently accepted phylogenetic informal clades of Malpighiaceae, we characterised the anatomy and/or histochemistry of two-thirds of Malpighiaceae genera and ten species from nine families of Malpighiales to test: 1. Do connective glands occur in the flowers of all informal clades of Malpighiaceae?; and 2. Are they taxonomically relevant to characterise those clades? We sampled 25 genera and 26 species of Malpighiaceae, processing their anthers using traditional anatomical methods and characterising their glands using light microscopy and SEM imaging. Selected species were subjected to histochemical tests, and an additional 21 genera and 33 species of Malpighiaceae and nine families (ten species) of Malpighiales were included in our sampling from the literature. Three anatomical characters were scored, coded and mapped using Maximum Likelihood methods onto the molecular phylogeny of Malpighiaceae. All sampled species of Malpighiaceae showed connective glands characterised as epidermal or trichomal elaiophores. Our character-mapping analyses recovered connective elaiophores as a new synapomorphy for Malpighiaceae. Different types of epidermal or trichomal elaiophores were recovered as homoplasies for the Christianella and Banisteriopsis clades and the genera Byrsonima, Camarea and Cottsia. Our analyses also recovered the glands' place of insertion in the stamen and the exudate type as potential new synapomorphies or homoplasies for the families of Malpighiales sampled. Our results propose the connective elaiophores as a new synapomorphy for Malpighiaceae and hypothesise the role that different staminal glands might play in the systematics of Malpighiales. Further comprehensive anatomical studies are still needed for the staminal glands of most families of this order to shed new light on the patterns recovered in our study. Citation: de Almeida RF, Arévalo-Rodrigues G, de Morais IL, Cardoso-Gustavson P (2023) Evolution of connective glands reveals a new synapomorphy for Malpighiaceae and the hidden potential of staminal glands for Malpighiales systematics. PhytoKeys 232: 109-131. https://doi.
... Essa coloração é típica de mucilagem em cortes frescos corados com esse corante (RIBEIRO & LEITÃO, 2020). É característico para os representantes Malvaceae a ocorrência de células, cavidades e ductos mucilaginosos em diversos órgãos do corpo da planta (BAYER & KUBITZKI, 2003), o que pode ser considerado uma sinapomorfia (GREGORY & BAAS, 1989) para o grupo. No caso de P. aquatica, foi observado em cortes longitudinais no presente trabalho que essas estruturas secretoras ocorrem na forma de fileiras de células, podendo assim ser interpretadas como ductos septados. ...
Pachira aquatica é uma árvore nativa da América do Sul utilizada na alimentação, obtenção de madeira e arborização urbana. Embora relativamente bem estudada, falta uma descrição estrutural detalhada dessa espécie. Portanto, o presente trabalho teve como objetivo descrever a anatomia dos órgãos vegetativos aéreos de P. aquatica crescendo no Semiárido Bahiano. Para este fim, foi utilizada metodologia usual em anatomia vegetal. A folha é palmaticomposta, hipoestomática, heterobárica, com mesofilo dorsiventral onde o parênquima lacunoso possui espaços intercelulares muito amplos. A nervura principal se projeta para ambas as faces e a de 2ª ordem apenas para a face adaxial. Na nervura principal ocorre uma fenda com tricomas secretores, tratando-se possivelmente de um nectário extrafloral. O pecíolo tem contorno circular em corte transversal. A vascularização consiste de um anel tetralobado de feixes vasculares colaterais. O caule em estrutura primária é pentalobado e possui braquiesclereides no córtex. Seus feixes vasculares são justapostos delimitando medula amilífera. Quando em estrutura secundária, o sistema axial do floema se organiza em grupos triangulares separados por raios centrifugamente mais abertos, quando observado em corte transversal. O lenho possui parênquima axial apotraqueal difuso a difuso em agregados. Os raios são uni ou multisseriados e heterocelulares. Ocorrem cristais do tipo drusa em todos os órgãos analisados. Também, idioblastos mucilaginosos longitudinalmente enfileirados nas nervuras de 1ª a 3ª ordem e no córtex e na medula do pecíolo e do caule. Conclui-se que P. aquatica tem características anatômicas adaptadas a ambientes úmidos bem como mais secos e seus órgãos em estrutura primária produzem abundante mucilagem. Sua madeira é aparentemente susceptível a trincas. Os órgãos analisados, pela facilidade no seccionamento a mão livre e pela variedade de estruturas interessantes, são um ótimo material para aulas práticas em anatomia vegetal.
... Essa coloração é típica de mucilagem em cortes frescos corados com esse corante (RIBEIRO & LEITÃO, 2020). É característico para os representantes Malvaceae a ocorrência de células, cavidades e ductos mucilaginosos em diversos órgãos do corpo da planta (BAYER & KUBITZKI, 2003), o que pode ser considerado uma sinapomorfia (GREGORY & BAAS, 1989) para o grupo. No caso de P. aquatica, foi observado em cortes longitudinais no presente trabalho que essas estruturas secretoras ocorrem na forma de fileiras de células, podendo assim ser interpretadas como ductos septados. ...
Resumo: Pachira aquatica é uma árvore nativa da América do Sul utilizada na alimentação, obtenção de madeira e arborização urbana. Embora relativamente bem estudada, falta uma descrição estrutural detalhada dessa espécie. Portanto, o presente trabalho teve como objetivo descrever a anatomia dos órgãos vegetativos aéreos de P. aquatica crescendo no Semiárido Bahiano. Para este fim, foi utilizada metodologia usual em anatomia vegetal. A folha é palmaticomposta, hipoestomática, heterobárica, com mesofilo dorsiventral onde o parênquima lacunoso possui espaços intercelulares muito amplos. A nervura principal se projeta para ambas as faces e a de 2ª ordem apenas para a face adaxial. Na nervura principal ocorre uma fenda com tricomas secretores, tratando-se possivelmente de um nectário extrafloral. O pecíolo tem contorno circular em corte transversal. A vascularização consiste em um anel tetralobado de feixes vasculares colaterais. O caule em estrutura primária é pentalobado e possui braquiesclereídes no córtex. Seus feixes vasculares são justapostos delimitando medula amilífera. Quando em estrutura secundária, o sistema axial do floema se organiza em grupos triangulares separados por raios centrifugamente mais abertos, quando observado em corte transversal. O lenho possui parênquima axial apotraqueal difuso a difuso em agregados. Os raios são uni ou multisseriados e heterocelulares. Ocorrem cristais do tipo drusa em todos os órgãos analisados. Também, idioblastos mucilaginosos longitudinalmente enfileirados nas nervuras de 1ª a 3ª ordem, no córtex e na medula do pecíolo e do caule. Conclui-se que P. aquatica tem características anatômicas adaptadas a ambientes úmidos bem como mais secos e seus órgãos em estrutura primária produzem abundante mucilagem. Sua madeira é aparentemente susceptível a trincas. Os órgãos analisados, pela facilidade no seccionamento a mão livre e pela variedade de estruturas interessantes, são um ótimo material para aulas práticas em anatomia vegetal. Palavras-chave: Árvore, estrutura, madeira, órgãos vegetativos, planta medicinal.
... Also, it allowed the identification of the chemical nature of the secretion, which is mucilaginous and composed mainly of neutral polysaccharides. Considering that the mucilage in eudicots is predominantly formed by acidic polysaccharides [41], the discussion about the presence of neutral polysaccharides in some monocots seems relevant and deserves attention. In Orchidaceae, in some rare reports of colleters in monocots, neutral polysaccharides in the exudates of these glands are reported for Rodriguezia venusta (Lindl.) ...
Araceae comprises a diverse group of plants that grow in various habitats, ranging from submerged aquatics to lithophytes. Thus, aroids are likely to show diverse glands acting in several plant–environment interactions, including colleters that protect young shoots. Based on this premise and the lack of studies regarding secretory structures in Araceae, we employed standard light and electron microscopy methods to test the hypothesis that colleters are present in Anthurium. Our main goals were to identify mucilage glands in A. andraeanum by conducting a detailed anatomical study of their structure, ultrastructure, and secretory activity. We found finger-like colleters in the apex of young leaves, spathes, and unexpanded cataphylls as well as secreting zones at the apex of expanded cataphylls, at the margins of non-fused cataphylls, and throughout the keels in two-keeled cataphylls. The colleters develop precociously and senesce shortly afterwards. Ultrastructural data and histochemistry confirmed the production of a polysaccharide-rich secretion that fills the spaces within the developing shoot. As far we know, this is the first time that colleters have been reported for Araceae. The functional roles of the secretion and the position of finger-like colleters concerning the ‘precursor tip’ of monocotyledons are discussed. Future research correlating secretory activity in colleters of species from different habitats might reveal a great diversity of mucilage glands with ecological and evolutionary significance to the family.
... Additionally, the mucilaginous idioblasts of Discolobium pulchellum have elongated forms extending to the mesophyll (Bento et al. 2023), distinct from the mucilaginous idioblasts observed in the other genera of the Pterocarpus clade. The presence of mucilage in leaflet epidermal cells can be useful in taxonomic approaches (Gregory and Baas 1989;Potgieter and Wessels 1998). Mucilaginous cells with a thin periclinal cell wall which divides the cell form a double layer in Acosmium cardenasii, as well as in the Chamaecrista (L.) Moench sect. ...
The Pterocarpus clade includes 23 genera previously attributed to different Fabaceae tribes. The recent rearrangements of many genera in the clade do not recognize morphological synapomorphies. This study aimed to identify new synapomorphies for the Pterocarpus clade, to identify characters supporting inter-generic relationships currently resolved only by molecular data and to identify diagnostic characters at the genus and species levels. Subterminal leaflets of the studied genera were selected and analyzed using light and scanning electron microscopy. Ancestral reconstruction was performed using morphological and anatomical characters of 16 genera of the Pterocarpus clade. The convex epidermal relief in the region of the main vein indicated the relationship among all genera of the group. Anchor-like multicellular trichomes are features shared by Brya and Cranocarpus, which are the sister group to the other genera of the clade. Subepidermal layers are features shared by the Centrolobium, Etaballia, Paramachaerium, Pterocarpus and Tipuana genera, and the sclerenchyma sheath in the leaflet margin is reported in the Discolobium, Riedeliella and Platymiscium genera. Bulbous based glandular trichomes and vesicular glandular trichomes are diagnostic at the species level in Centrolobium and Pterocarpus, respectively. The leaflet characters investigated can be useful for the taxonomic delimitation at both the genus and species levels of the Pterocarpus clade. Our dataset provides new synapomorphies, elucidates the inter-generic relationships and reinforces the phylogenetic classification of the Pterocarpus clade resolved by molecular data.
... The blocks were sectioned in a rotary microtome (RM 2045, Leica Biosystems, Heidelberg, Germany) at 5-7 μm thickness. Sections on slides were stained with ruthenium red for pectins and polysaccharides [47] and mounted with synthetic resin (Entellan ® , Merck, Darmstadt, Germany) to analyze the epidermis and its outer cell walls. Sudan IV was used to detect lipids to delimit the cuticle [48]. ...
The epidermis and cuticle play an important role in reducing dehydration and protecting the cashew pseudofruit in both the production environment and the postharvest stage. This study analyzes the alterations on the epidermis and cuticle of CCP 76 cashew pseudofruits harvested in five developmental and maturation stages (S1, S2, S3, S4, and S5). The epidermis and cuticle of the samples were analyzed under light microscopy (LM) (quantitative analysis), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The epidermal cells at S3 reached maximum outer periclinal wall thickness, which reduced during ripening (S4 and S5), while the cuticle increased in thickness during the same period. These changes coincided with the rapid initial growth of the cashew pseudofruit when the epidermis and cuticle need to accompany the expansion of internal tissues. At the ultrastructural level, lipid material is transported via vesicles through the cell wall to the cuticle, increasing its thickness. Epicuticular waxes, previously deposited as plates and globules, began to develop an amorphous shape during maturation. This process possibly occurs due to changes in wax composition that can be related to the development of greasiness on the fruit skin. These findings provide a better understanding of cashew pseudofruit skin, which will aid future studies and strategies to preserve quality during the postharvest stage.
... We investigated the presence of secretory tissues by immersing fresh flowers in 0.1 % (w/v) aqueous neutral red for 20 min (Vogel, 1962;time adapted). To detect mucilage location, we immersed the fresh flowers in ruthenium red for 5 min (Gregory and Baas, 1989; time adapted). We submitted longitudinal handmade cuts from flower samples to histochemical tests to detect chemical compounds related to pollination process. ...
Background and Aims
Trap flowers are fascinating cases of adaptation, often linked to oviposition site mimicry systems. Some trap flowers do not imprison pollinators for a pre-determined period, but rather force them to move through a specific path, manipulating their movements in a way that culminates in pollen transfer, often as they leave through a secondary opening.
Methods
We investigated the previously unknown pollination system of the lady’s slipper orchid Phragmipedium vittatum and assessed the function of micro-morphological traits of its trap flowers.
Key Results
Our observations revealed that P. vittatum is pollinated by females of two hoverfly species (Syrphidae). Eggs laid by flies on or near raised black spots on the flowers indicate that the orchid mimics aphids which serve as food for their aphidophagous larvae. Dark elevated aphid-like spots appear to attract the attention of hoverflies to a slipping zone. This region has downward projecting papillate cells and mucilage secretion that promote slipperiness, causing potential pollinators to fall into the labellum. They then follow a specific upward route towards inner aphid-like spots by holding onto upward oriented hairs that aid their grip. As hoverflies are funneled by the lateral constriction of the labellum, they pass the stigma, depositing pollen they may be carrying. Later, they squeeze under one of the articulated anthers which places pollen smears onto their upper thorax. Then, they depart through one of the narrow lateral holes by holding onto hairs projecting from the petals.
Conclusions
This study confirms the system of aphid mimicry in Phragmipedium and highlights the sophisticated micro-morphological traits used by trap flowers in pollinator attraction, trapping, guidance, and release, thus promoting precise pollen transfer.
... For histochemical analyses, sections were subjected to tests with Sudan IV (Jensen 1962), Sudan Black B (Pearse 1968) and Nile blue sulphate (Cain 1947) for lipids; methylene blue for basic mucilage (Johansen 1940); ruthenium red for acidic mucilage (Gregory & Baas 1989); ferric chloride for phenolic compounds (Johansen 1940); and PAS reagent for total polysaccharides (Periodic Acid-Schiff) (McManus 1948). Fresh material (not fixed) and sections of historesin-embedded samples containing colleters were also tested for acidic mucilage and phenolic compounds, as described above, and for proteins using 1% xylidine ponceau (pH 2.5; Vidal 1970). ...
Location and degree of protection of aerial buds are important functional traits in disturbance‐ or stress‐prone environments since aerial buds ensure the development of new organs under favourable growing conditions. This study was carried out in a Brazilian Cerrado area under regeneration after long‐term Pinus cultivation, where the trees were clear‐cut in 2012 and the remaining material was burned in 2014.
After the fire treatment, several species resprouted from belowground organs and their aboveground organs were directly exposed to full sunlight. We collected 15 terminal branches with fully expanded leaves from three individuals of each of three Eugenia species to investigate if those with well‐developed belowground organs invest in bark for aboveground bud protection. The samples were analysed using light and electron microscopy.
In addition to terminal and axillary buds, all species presented accessory buds, and the number varied according to the node analysed. None of the aerial buds were protected by bark, but all were well protected by cataphylls and densely pubescent leaf primordia. There were also inter‐ and intra‐petiolar colleters that released a mucilaginous protein exudate. The distance between the shoot apical meristem and the outer surface was longer in the terminal bud than in axillary buds. The bud leaf primordia covering the shoot apical meristem had a thick cuticle, unicellular non‐glandular trichomes that accumulate phenolic and lipophilic compounds, and secretory cavities.
Our study shows that all three Eugenia species studied here had highly protected aerial buds allocated from belowground organs. These morphological traits may improve the chances of the species' persistence in areas subjected to frost events, low relative humidity, high irradiance and harmful UV levels.
... Interestingly, these mucilaginous idioblasts found in B. graminifolia also have chloroplasts; however, they are less developed than those found in typical chlorophyll cells, reinforcing the primary role of these cells in the synthesis and distribution of mucilaginous content. According to Gregory and Baas (1989), in this context, the mucilage, including carbohydrates, in the mucilaginous cells of the vegetative organs would be reabsorbed at different periods. ...
Barbacenia graminifolia is a Velloziaceae species endemic to the campos rupestres in Serra do Cipó, Minas Gerais state (Brazil). This biome is characterised by high irradiance and limited water conditions. Unlike other resurrection plants, B. graminifolia can maintain a high hydric status (> 80%) after 28 days of water suppression before desiccation. We investigated the physiological and metabolic mechanisms associated with structural changes that allow B. graminifolia to maintain hydration under a prolonged water deficit and to recover after desiccation. After 30 days of water deficit, desiccated plants exhibited chlorophyll degradation, a 178.4% and 193.7% increase in total carotenoids and MDA, respectively, and twice the CAT and APX activity compared to hydrated plants. The metabolite profile showed increased amino acids, carbohydrates, saturated fatty acids, and benzoic acids during dehydration, while TCA cycle acids were higher in hydrated and rehydrated plants. Anatomical and ultrastructural data corroborated the physiological and metabolic changes and revealed the presence of mucilaginous cells with high water retention capacity. Our data indicated that combined strategies of assimilatory metabolism shutdown, accumulation of compatible solutes and antioxidant compounds, increase in hydrophilic molecules, changes in the composition of membrane lipids, and remodelling of cell organelles conditioned the efficiency of B. graminifolia in delaying water loss, tolerating further desiccation, and quickly recovering after rehydration. These attributes evidence that this species is well adapted to cope with adverse environmental conditions, mainly directing the metabolism to an efficient antioxidant response and improving its capacity to retain water during the dry season.
Nectaries in Malvaceae are in general trichomatous glandular structures usually aggregated in cushions. However, little is known on the diversity of nectaries in the Bombacoideae subfamily. Pseudobombax argentinum presents two contrasting types of nectaries in the flower that were investigated for the first time using light, confocal laser and scanning electron microscopy, and field observations. Sepal nectaries are elevated glands on the abaxial side of the calyx tube. The exuded nectar was exclusively consumed by ants in the period between the flower bud development and the anthesis. The nectaries consist of secretory epidermis, nectary, and subnectary parenchyma. The two latter tissues are vascularized by phloem and xylem. Nectar release could occur both through the rupture of the cuticle or through the papillae. Histochemical tests indicated that secretions on the epidermis presented polysaccharides, pectins, and proteins. The second type of nectary corresponds to secreting areas on the external side of the staminal tube, which were active when the flower opening was initiated in the early evening and for 2 days. Bees and hummingbirds searched for this nectar in daylight hours. These nectaries are non-structural, with nectarostomata probably involved in the nectar release. Our findings suggest that the primary function of sepal nectaries is to attract and feed ants, while staminal nectaries play a role in rewarding pollinators. Both nectaries are non-trichomatous. The evaluation of variations in nectaries may be useful to determine evolutionary changes of this trait and its systematic importance. Thus, a comparison of nectary types across the Malvaceae groups is presented.
This research was performed at the greenhouse facilities of the Department of Horticulture Engineering at Samarra University during the 2023–2024 growing season, under the Faculty of Agriculture. The study aimed to determine the response of Fragaria ananassa Duch to salicylic acid and sugar alcohol spray. This investigation consisted of three elements: The initial factor to examine is the soil type: S1, mixed; S2, gypsum; The second ingredient pertained to three tiers of sugar alcohols, solely water. T0 and sugar alcohols at a concentration of 3 ml L ⁻¹ T2 containing six milliliters. T3 L ⁻¹ The third component is salicylic acid, which possesses three levels of comparative treatment. C0 with salicylic acid at a dosage of 20 mg.L ⁻¹ C1 at 40 mg.L ⁻¹ C2.Specifically at 6 ml. liters ⁻¹ , the application of sugary alcohols resulted in an average growth increase.12.33 μm, 10.67 μm, 6.17 μm, 5.67 μm, 156.1 mm ² in the dimensions of the gaps on the lower and upper surfaces 12.33 μm, 10.67 μm, 6.17 μm, 5.67 μm. Moreover, salicylic acid application, particularly at a dosage of 40 mg, was most effective L ⁻¹ C demonstrated a significant enhancement in the examined parameters, encompassing the leaf gap frequency on both sides and the expansion rate of the length and width of gaps on both the upper and bottom surfaces. 11.94, 10.50 μm, 5.50, 5.00 μm, 161.0, 5.17 mm ² .Bilateral and triangular interactions among salicylic acid, sugar alcohols, and various soil types exhibited significant discrepancies across all examined parameters.
The anatomical and cytological characteristics of the mucilage secretory system have been widely studied in Malvaceae. However, conflicting information regarding the morphological nature of secretory structures exists, and some remain poorly understood. In this sense, some secretory structures in Malvaceae are not characterized as typical isolated idioblasts, canals, or cavities. Here, we describe a novel component of the mucilage-secretory apparatus in the Malvaceae family. Samples of the shoot apex, mature stem, and fully expanded leaves were obtained from adult Peltaea polymorpha, which grow in the Cerrado (Brazilian savanna). The samples were processed using standard light and transmission electron microscopy methods. Mucilage cells occurred in the cortex and pith of petioles and stems, and in the midrib of leaves. These cells originate early in the stem apex from successive divisions of cells of the fundamental meristem, resulting in a row of interconnected secretory cells enveloped by a sheath of parenchyma cells devoid of secretory activity. Mucilage is stored in both protoplast and apoplast. In a same row, some cells filled with mucilage become very swollen and compress the neighboring idioblasts that become flattened. This phenomenon results in a sandwich panel structure consisting of the swollen transversal walls of adjacent cells. As the differentiation progresses, the transversal walls of the rowed mucilage cells became very swollen, multilayered, and porous. Cytoplasmic strands cross such transversal walls connecting rowed cells. Mucilage-secreting cells in P. polymorpha are interconnected idioblasts and represent a novel component of the mucilage-secretory apparatus in Malvaceae. These findings open new avenues for understanding the structure and dynamics of mucilage-secreting cells from a functional perspective.
Aiming to verify whether the diversity of secretory structures with their respective exudates are or not responsible for the attendance of floral visitors in Miconia species, the floral secretory structures of two Amazonian species of Miconia were described and interpreted from the functional perspectives and observations of floral visitors. Flowers and floral visitors were collected in the field for 16 months. The flowers were subjected to standard anatomical analyzes using light and scanning electron microscopy, and the secretory structures were evaluated using histochemical tests. The insects were photographed, collected and identified by a specialist. Floral secretory structures (stigmatic papillae and trichomes at the apex of the ovary) were found in M. alata and M. ciliata. Trichomes were found at the hypanthium of M. alata, and of the sepals and receptacles in M. ciliata. In both species, different hydrophilic compounds were detected in the exudates. Only phenolic compounds were found in the trichomes of the M. ciliata receptacle. This study provides information that confirms the hypothesis that other secretory structures and exudates are related to floral visitors, and adds new informations about the features of the secretory structures in Miconia.
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4934318
Halophytes are characterized by their ability to survive in environments with high salinity, and many of these species eliminate excess salts through secretory structures, such as salt glands or bladders. Rhizophora mangle, however, is a halophyte that does not have specialized structures for eliminating salts, but it does have lenticels located on the lower surface of the leaves. These lenticels are not only involved in oxygenating plant tissues, but they can also eliminate toxic substances. Thus, we hypothesized that the lenticels could act as structures involved in the elimination of excess salts. In this study, we used light microscopy to observe the occurrence of lenticels on the stipules and both young and adult leaves of R. mangle. Using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), we also analyzed the composition of chemical elements found in the extrusion content of lenticels. The origin of lenticels, both stipular and foliar, is stomatal, and, at the end of development, the stomatal complex is degraded, generating the opening pore. Sea salt was observed on the surface of leaf lenticels, as evidenced by EDX-SEM. The most representative elements on the surface of the lenticels were Cl, Ca, and Na, respectively. In this way, we suggest that the lenticels in R. mangle act as pores through which minerals, such as Na, Cl, Ca, K, Mg, P, S, and Si, can be eliminated by the leaves, an important strategy to maintain the osmotic balance of a typical mangrove species growing in a tropical region.
Dalea purpurea , an herbaceous papilionoid legume of the North American Great Plains, has floral characteristics that are highly atypical within subfamily Papilionoideae, such as organs reduction, low differentiation among petals, with keel absence, adnation between petals and stamens and presence of anther glands. This study aims to elucidate the ontogenetic processes responsible for its atypical architecture. Floral buds and flowers were processed by scanning electron microscope (SEM) and light microscope (LM). Five sepals initiate in a modified unidirectional order, followed by five petals simultaneously. The five antesepalous stamens initiate in a bidirectional order. No antepetalous stamens primordia were initiated, suggesting that the presumed evolutionary reduction from ten to five stamens in Dalea was due to ontogenetic pathway organ absence since the initiation. The single and central carpel is precocious, emerges concomitantly with the first stamen primordium. The hypanthium is short, and the ovary is superior, with a short stipe. The five anthers are dorsifixed and rimose, with elongated glandular dorsal and apical appendages. The petals are clawed, and positioned like a hood above the reproductive whorls during development. We found an adnation of the basal region of the filaments to the petal claws, forming a stemonozone. The structure, on the abaxial side, forms an elongated sheath through the adnation of the stamens to four weakly differentiated petals to the height of the calyx lacinia. The adaxial petal (banner) is free for the most part, with adnation only at the base of the stemonozone, forming the apron. The peculiar feature absence of the typical staminal tube seems to be circumvented by the adnation of the five stamens to the five petals and the position of the adaxial petal in D. purpurea , which looks like it performs a similar function to that of the diadelphous staminal tube of other Papilionoideae. The diversity and distribution of floral secretory structures indicate that this species, which lost part of its floral specialization, might be using chemical defenses as protection against the predation of the reproductive organs. Thus, we conclude that the atypical Dalea pupurea ’s floral architecture is due to some ontogenetic events associated with evolutionary and environmental pressures.
Brazil is one of the main centers of biological heterogeneity of the Cactaceae family vegetables, representing around 33% of the world’s genera (Zappi et al. 2015). These cacti, especially their cladodes, are usually purposed as animal fodder (Sousa 2017). New studies, however, present some species, such as Opuntia fícus-indica L. (palm), Cereus jamacaru D.C. (mandacaru), Pilosocereus gounellei (xique-xique), and Pilosocereus pachycladusr (facheiro), as sources for useful substances, like mucilages (Vieira et al. 2021).
Abstract Rocky outcrops are known for low humidity, rainfall and high solar radiation, factors that limit the development of some vegetables. However, some species of the genus Anemia occurring in these environments. Thus, understanding the anatomical characters present in these vegetables are important for botanical and biodiversity knowledge in rock fields. We described the leaf anatomy of six species of Anemia to identify characters adapted to rocky outcrops for ferns. Herbarium samples were rehydrated. Field-collected leaves, were also sampled, the material was subjected to standard anatomical study by light microscopy, and secretions were evaluated by histochemical of the secondary compounds, with ruthenium red, tannic acid, ferric chloride, lugol, Sudan black B, vanillin/hydrochloric acid, Dragendorff’s reagent and ponceau xylidine. Histochemical tests were positive for phenolic compounds, alkaloids, polysaccharides, and proteins in A. buniifolia, A. oblongifolia, A. presliana, and A. trichorhiza. Our findings revealed that several structural and histochemical characters of Anemia with trichomes, conical stegmatas, phenolic compounds, mucilages and alkaloids are related to reducing water loss, providing an adaptive value to species in extreme environments, such as rocky outcrops, in addition to new data relevant to the group taxonomy, such as the presence of amphistomatic leaves in A. trichorhiza.
Mayer's stain for animal mucins was found to be selective for the mucilages of Tilia, imparting to them a black color. Embedded stem sections and the slimy secretions of cut stems were treated with 5% aqueous tannic acid for 10 min, washed, treated with 3% aqueous ferric chloride for 1 min, washed, and dried. Because of the scarcity of histochemical techniques selective for plant mucilages, Mayer's stain for mucins merits further testing among other plants which synthesize mucilages.
Maihuenia, a genus of pulviform cacti endemic to southern South America, is anatomically described for the two putative species. Stems of both species have medullary and cortical mucilage reservoirs, no collenchymatous hypodermis, and an unusual epidermis with tangentially thickened primary walls. Unlike Opuntioideae, Maihuenia lacks stellate druses in the outermost cortex. The small, terete leaves have a central mucilage reservoir surrounded by a vascular reticulum, large mucilage cells within the chlorenchyma, and an epidermis similar to that of the stem. Stem secondary xylem is at first nonfibrous, composed of very short and narrow vessel elements and vascular tracheids with secondary thickenings and unlignified fusiform parenchyma cells. Older stems produce clusters of short libriform fibers in discontinuous concentric bands, pitted vessel elements, few, if any, vascular tracheids, and unlignified fusiform parenchyma cells. Wood fiber production occurs earlier in decumbent stems than in basal stems, but fibers are evidently more abundant in basal portions. The main root is highly succulent and produces no wood fibers, whereas large secondary and very thin adventitious roots are progressively less succulent and produce fibers. Ontogenetic changes in xylem cell types and lateral walls in Maihuenia are more easily understood from analyses of differences in growth regulator concentrations rather than arguments based solely on plant-water relationships and mechanical considerations. Vegetative features of Maihuenia negate its inclusion in Opuntioideae and suggest that Maihuenia shares ancestry with certain large-leaved, fruticose species of Pereskia endemic to the Andes.
Neben der Geschichte und dem medizinischen Gebrauch von Borago officinalis wird die Anatomie der Blätter und Blüten beschrieben.