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Pansarin LM, Pansarin ER, Alves-Dos-Santos I, Teixeira SP. So small and so rich: diversity of floral resources in miniature Oncidiinae (Orchidaceae) and their relation to pollinators. PLANT BIOLOGY (STUTTGART, GERMANY) 2021; 23:259-266. [PMID: 33222376 DOI: 10.1111/plb.13221] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 11/11/2020] [Indexed: 06/11/2023]
Abstract
Oncidiinae is one of the most important subtribes among the Neotropical orchids, with an enormous diversity of floral morphology and secretory structures. This subtribe attracts a diverse array of pollinators which explore a variety of floral resources of its flowers. In this paper we provide a detailed investigation of the floral anatomy of 32 species of micro Oncidiinae. We applied histochemical tests in order to determine the diversity of the glands and rewards. The diversity of secretory flower structures and rewards was related to the group of pollinators known for this subtribe. We verified that half of the species (16 species, 50%) secrete oil as a resource, being pollinated by female of solitary bees. Species of some distinct nectar-secreting genera (four species, 12.5%) are pollinated by a range of nectar-searching animals. Species of the genus Notylia (four species, 12.5%) release floral perfumes that reward male Euglossini bees. Most of the investigated species (six species, 18.75%) possess osmophores that are involved in pollinator attraction. Two species of Capanemia (6.25%) do not offer any floral reward, suggesting that pollination by food deception is involved. There are strong variations in the anatomy of reward-producing structures and resources in Oncidiinae. The diversity of floral rewards affects the range of pollinators, which are related to the diversification of this subtribe throughout the Neotropics. The understanding of relationships between Oncidiinae species and their pollinators is crucial to our knowledge of the evolution of pollination systems in this huge plant family represented by the orchids.
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Affiliation(s)
- L M Pansarin
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - E R Pansarin
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - I Alves-Dos-Santos
- Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - S P Teixeira
- Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Ribeirão Preto, Brazil
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Diversity of Floral Glands and Their Secretions in Pollinator Attraction. REFERENCE SERIES IN PHYTOCHEMISTRY 2020. [DOI: 10.1007/978-3-319-96397-6_48] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Kettler BA, Solís SM, Ferrucci MS. Comparative survey of secretory structures and floral anatomy of Cohniella cepula and Cohniella jonesiana (Orchidaceae: Oncidiinae). New evidences of nectaries and osmophores in the genus. PROTOPLASMA 2019; 256:703-720. [PMID: 30470901 DOI: 10.1007/s00709-018-1330-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 11/14/2018] [Indexed: 06/09/2023]
Abstract
The morpho-anatomical structure of nectaries, osmophores, and elaiophores, and the anatomical and micromorphological features of floral pieces of Cohniella cepula Hoffmans. and Cohniella jonesiana Rchb.f. were comparatively analyzed. In both species, bracteal and sepal nectaries are structured, i.e., they present a secretory epidermis, secretory parenchyma, and vascular bundles. Nectar secretion is released through stomata. The anatomical and micromorphological traits are similar in both nectaries, which can be detected only if the nectar drops are secreted. Considering the location of these nectaries, the secreted nectar would not be a reward to pollinators. Osmophores are located at the base of both callus and laterals lobes, and consist of a layer of secretory epidermis composed of quadrangular cells and papillae. Elaiophores are found on the callus of the labellum and are of the epithelial type. The anatomical features of floral pieces are similar in both species. The anatomical analysis of sepals and petals showed a few differences, which could be of potential taxonomic value. Our results contribute valuable and novel information for the knowledge of these species and the genus, which will be useful in future taxonomic evaluations.
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Affiliation(s)
- Belén Araceli Kettler
- Centro de Ecología Aplicada del Litoral (UNNE-CONICET), Ruta 5 km 2.5, 3400, Corrientes, Argentina
- Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste, Sargento Cabral 2131, 3400, Corrientes, Argentina
| | - Stella Maris Solís
- Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste, Sargento Cabral 2131, 3400, Corrientes, Argentina
- Facultad de Ciencias Exactas y Naturales y Agrimensura, Universidad Nacional del Nordeste, Av. Libertad 5470, 3400, Corrientes, Argentina
| | - María Silvia Ferrucci
- Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste, Sargento Cabral 2131, 3400, Corrientes, Argentina.
- Instituto de Botánica del Nordeste (UNNE-CONICET), Sargento Cabral 2131, 3400, Corrientes, Argentina.
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da Silva Pereira P, de Almeida Gonçalves L, da Silva MJ, Rezende MH. Extrafloral nectaries of four varieties of Chamaecrista ramosa (Vogel) H.S.Irwin & Barneby (Fabaceae): anatomy, chemical nature, mechanisms of nectar secretion, and elimination. PROTOPLASMA 2018; 255:1635-1647. [PMID: 29704049 DOI: 10.1007/s00709-018-1253-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Accepted: 04/09/2018] [Indexed: 06/08/2023]
Abstract
Considering the importance of extrafloral nectaries (EFNs) in Fabaceae, the objectives of this research were to analyze (1) the anatomical and histochemical characteristics of the EFNs of Chamaecrista ramosa var. ramosa, C. ramosa var. curvifoliola, C. ramosa var. parvifoliola, and C. ramosa var. lucida and (2) the ultrastructure of the EFNs of C. ramosa var. ramosa. Standard techniques in plant anatomy and transmission electron microscopy were used. The anatomical analyses confirmed the characteristics described for extrafloral nectaries, evidencing three well-defined regions: epidermis, nectariferous, and subnectariferous parenchymas. Carbohydrates, proteins, pectins/mucilages, and lipids were detected by histochemical analyzes in all varieties. The ultrastructure of the EFNs of C. ramosa var. ramosa allowed the observation of microchannels at the external periclinal cell walls of the epidermis covering the secretory region. The nectariferous and subnectariferous parenchyma cells have periplasmic spaces, large plastids containing starch grains and plastoglobules, mitochondria, developed endoplasmic reticulum, large vacuoles with electron-dense contents, and membrane residues may be associated with the vacuole, suggesting the occurrence of autophagic processes. The anatomical, histochemical, and ultrastructural patterns revealed characteristics that confirm the glands of C. ramosa as extrafloral nectaries and suggest the eccrine mechanism of secretion.
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Affiliation(s)
- Priscila da Silva Pereira
- Pós-graduação em Biodiversidade Vegetal, Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Avenida Esperança, S/N, Campus Samambaia, ICB - 1, 2nd floor, room 206, Goiânia, 74690-900, Brazil.
| | - Letícia de Almeida Gonçalves
- Pós-graduação em Biodiversidade Vegetal, Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Avenida Esperança, S/N, Campus Samambaia, ICB - 1, 2nd floor, room 206, Goiânia, 74690-900, Brazil
| | - Marcos José da Silva
- Pós-graduação em Biodiversidade Vegetal, Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Avenida Esperança, S/N, Campus Samambaia, ICB - 1, 1st floor, room 114A, Goiânia, 74690-900, Brazil
| | - Maria Helena Rezende
- Pós-graduação em Biodiversidade Vegetal, Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Avenida Esperança, S/N, Campus Samambaia, ICB - 1, 2nd floor, room 206, Goiânia, 74690-900, Brazil
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Płachno BJ, Stpiczyńska M, Krajewski Ł, Świątek P, Adamec L, Miranda VFO. Flower palate structure of the aquatic bladderworts Utricularia bremii Heer and U. minor L. from section Utricularia (Lentibulariaceae). PROTOPLASMA 2017; 254:2007-2015. [PMID: 28290058 PMCID: PMC5610218 DOI: 10.1007/s00709-017-1097-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 03/01/2017] [Indexed: 05/11/2023]
Abstract
There is an enormous diversity in the structure of the flower palate of the carnivorous rootless genus Utricularia. This study aims to examine the structure of the palates in Utricularia bremii Heer and U. minor L of the Utricularia sect. Utricularia, which have a glandular palate type. In both species, the palate has only one type of glandular trichomes. Because of the occurrence of cell wall ingrowths in its glandular cells, any exudation may be transported via eccrinous secretion. It was proposed that the palate trichomes of the examined species act as scent glands and that the palate may play a role as an unguentarium. Both U. bremii and U. minor are of an open flower type. Thus, U. bremii and U. minor flowers can be penetrated by small, weak insects, which then easily have access to their generative structure. Small Hymenoptera (member of families Mymaridae and Braconidae) were observed as flower visitors of the male-sterile species Utricularia bremii.
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Affiliation(s)
- Bartosz J Płachno
- Department of Plant Cytology and Embryology, Jagiellonian University in Kraków, 9 Gronostajowa St., 30-387, Kraków, Poland.
| | - Małgorzata Stpiczyńska
- Faculty of Biology, Botanic Garden, University of Warsaw, Al. Ujazdowskie 4, 00-478, Warsaw, Poland
| | - Łukasz Krajewski
- Wetland Conservation Center, ul. Cieszkowskiego 1-3/31, 01-636, Warszawa, Poland
| | - Piotr Świątek
- Department of Animal Histology and Embryology, University of Silesia in Katowice, 9 Bankowa St., 40-007, Katowice, Poland
| | - Lubomír Adamec
- Institute of Botany of the Czech Academy of Sciences, Section of Plant Ecology, Dukelská 135, CZ-37982, Třeboň, Czech Republic
| | - Vitor Fernandes Oliveira Miranda
- Faculdade de Ciências Agrárias e Veterinárias, Jaboticabal, Departamento de Biologia Aplicada à Agropecuária, Universidade Estadual Paulista (Unesp), São Paulo, Brazil
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Pansarin ER, Alves-Dos-Santos I, Pansarin LM. Comparative reproductive biology and pollinator specificity among sympatric Gomesa (Orchidaceae: Oncidiinae). PLANT BIOLOGY (STUTTGART, GERMANY) 2017; 19:147-155. [PMID: 27860055 DOI: 10.1111/plb.12525] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 11/07/2016] [Indexed: 06/06/2023]
Abstract
The incredible pollination mechanisms displayed by orchid flowers has inspired biologists over the centuries. Based on the intriguing flower structures, the relationship among orchid species and their pollinators has been frequently regarded as very specialised. Given that visits on flowers pollinated by oil-collecting bees are regularly rare, and in Oncidiinae the flowers frequently attractexclusively species that act as effective pollinators, the comparative reproductive biology and pollinator specificity of two sympatric Gomesa (G. varicosa and G. montana; Oncidiinae) were analysedbased on records of floral morphology, production of floral rewards, pollinators and pollination mechanisms. Furthermore, experimental pollinations were carried out in order to examine the breeding systems. The results have show that in the studied population, both Gomesa are visited by several bee species, but these orchids present a specific pollination system.Pollinaria are deposited on the head of Centridini (G. varicosa and G. montana) and Epicharitini (G. varicosa) bees when landed on the central callus of the labellumto collect lipoidal substances produced by glandular elaiophores on lateral lobes of the labellum. Both species are dependent on a biotic pollen vector to set fruits. Gomesamontana is completely self-incompatible, while G. varicosa is partially self-compatible. Our results indicate that although the occurrence of self-sterile species seems to be common in Oncidiinae, in partially self-incompatible species, as is the case of G. varicosa, self-compatibility has been considered as an important factor favouring reproductive assurance in populations with low visitation frequencies, despite occurrence of inbreeding depression.
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Affiliation(s)
- E R Pansarin
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras, Universidade de São Paulo, Ribeirão Preto, Brasil
| | - I Alves-Dos-Santos
- Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brasil
| | - L M Pansarin
- Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brasil
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Guo J. Mechanisms for the evolution of complex and diversely elaborated sepals in Iris identified by comparative analysis of developmental sequences. AMERICAN JOURNAL OF BOTANY 2015; 102:819-32. [PMID: 26101409 DOI: 10.3732/ajb.1400519] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 05/11/2015] [Indexed: 05/28/2023]
Abstract
PREMISE OF THE STUDY Crested sepals, which have evolved at least five times in Iris, are adaxially elaborated with a sinuous and/or uneven median structure (crest) along the proximal-distal axis and sometimes with various lateral structures (ridges, crests, and linear protuberances) flanking the median crest. These structural elaborations are complex yet diverse in form, providing a good opportunity to investigate developmental mechanisms for the diversification of reproductive lateral organs. METHODS Morphologies of the median and lateral structures at different developmental stages from selected crested sepals representing the major types of structural elaborations were recorded using scanning electron microscopy and light microscopy. Developmental (morphogenetic) events that contribute to changes in shape (e.g., sinuousness, unevenness) between consecutive stages were recorded. Developmental sequences-trajectories that consist of a series of developmental events-were compared in a phylogenetic context. KEY RESULTS Three developmental events (development of outgrowths, greater expansion of the upper zone, and greater expansion of the lower zone), are shared across lineages, occur in the same developmental sequences, and are responsible for the changes in shape during the development of diverse structural elaborations. In addition, two novel developmental events and the development of trichomes on elaborate structures were observed within the core-crested clade. CONCLUSIONS Developmental sequences are conserved across independently evolved crested lineages. Heterochronic and heterotopic shifts of developmental events play the major role in the diversification of elaborations of crested sepals in Iris. The evolution of novel developmental events and the development of trichomes also contribute to the diversity.
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Affiliation(s)
- Jinyan Guo
- Department of Biology, Brigham Young University, Provo, Utah 84602 USA
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Davies KL, Stpiczyńska M. Labellar anatomy and secretion in Bulbophyllum Thouars (Orchidaceae: Bulbophyllinae) sect. Racemosae Benth. & Hook. f. ANNALS OF BOTANY 2014; 114:889-911. [PMID: 25122654 PMCID: PMC4171068 DOI: 10.1093/aob/mcu153] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 06/12/2014] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS Floral secretions are common in Bulbophyllum Thouars, and the labella of a number of Asian species are said to produce secretions rich in lipids that act as food rewards for insect pollinators. Although some of these reports are based on simple histochemical tests, a much greater number are anecdotal and, hitherto, neither the ultrastructure of the labellum nor the secretory process has been investigated in detail. Furthermore, sophisticated histochemical approaches have generally not been applied. Here, both the labellar structure and the secretory process are investigated for four species of Asian Bulbophyllum sect. Racemosae Benth. & Hook. f., namely Bulbophyllum careyanum (Hook.) Spreng., B. morphologorum Kraenzl., B. orientale Seidenf. and B. wangkaense Seidenf., and compared with those of unequivocal lipid-secreting orchids. METHODS Labellar, secretory tissue was investigated using light microscopy, scanning electron microscopy, transmission electron microscopy and histochemistry. KEY RESULTS The adaxial median longitudinal groove of the labellum contained secretory tissue comprising palisade-like epidermal cells, similar to those of certain lipid-secreting Oncidiinae Benth. However, these cells and their secretions gave positive results mainly for protein and mucilage, and their organelle complement was consistent with that of cells involved in protein and mucilage synthesis. Sub-cuticular accumulation of secretion resulted in cuticular distension and blistering. The sub-epidermal layer of isodiametric parenchyma contained starch and, like the epidermal cells, ultrastructure consistent with mucilage synthesis. Lipids were mainly confined to the cuticle, and hardly any intracellular lipid droplets were observed. CONCLUSIONS It is proposed that mucilage is produced by dictyosomes present in the palisade-like epidermal cells. Mucilage precursors may also be produced by these same organelles in sub-epidermal cells and are thought to pass along the symplast via plasmodesmata into the adjoining palisade-like secretory cells, which contain abundant arrays of rough endoplasmic reticulum. Here, they become chemically modified and form a protein-rich, mucilaginous secretion that, following vesicle-mediated transport across the cytoplasm, traverses the cell wall and accumulates in blisters formed from the distended cuticle. Rupture of these blisters releases the secretion onto the labellar surface. However, in certain species, there is some evidence that the secretion may traverse the cuticle via cuticular pores, and micro-channels may permit the passage of fragrance. Hydrolysis of sub-epidermal starch probably generates the carbohydrate and, together with mitochondria, much of the energy required for the secretory process. This anatomical organization resembles that found in certain lipid-secreting, Neotropical species of Bulbophyllum and Oncidiinae, but since the chemical composition of their secretions is different, and these taxa occur on a separate continent and have different insect pollinators, parallelism of floral anatomy is likely.
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Affiliation(s)
- Kevin L Davies
- School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK
| | - Malgorzata Stpiczyńska
- University of Warsaw, Faculty of Biology, Botanic Garden Al. Ujazdowskie 4, 00-478 Warsaw, Poland
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Davies KL, Stpiczyńska M, Rawski M. Comparative anatomy of floral elaiophores in Vitekorchis Romowicz & Szlach., Cyrtochilum Kunth and a florally dimorphic species of Oncidium Sw. (Orchidaceae: Oncidiinae). ANNALS OF BOTANY 2014; 113:1155-73. [PMID: 24737719 PMCID: PMC4030811 DOI: 10.1093/aob/mcu045] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 02/19/2014] [Indexed: 05/23/2023]
Abstract
BACKGROUND AND AIMS Recently, molecular approaches have been used to investigate the phylogeny of subtribe Oncidiinae, resulting in the re-alignment of several of its genera. Here, a description is given of the structure of the floral elaiophores (oil glands) of four species formerly assigned to Oncidium Sw. Those of Vitekorchis excavata (Lindl.) Romowicz & Szlach., Cyrtochilum meirax (Rchb.f.) Dalström and a species of Oncidium displaying floral dimorphism, namely O. heteranthum Poepp. & Endl. var. album, are compared with that of Gomesa longipes (Lindl.) M.W. Chase & N.H. Williams, whose epithelial elaiophores are typical of many Oncidiinae, in order to extend our understanding of elaiophore diversity within this subtribe. METHODS Floral elaiophore structure was examined and compared at anthesis for all four species using light microscopy, scanning electron microscopy, transmission electron microscopy and histochemistry. KEY RESULTS In all species investigated, with the exception of C. meirax, the floral elaiophore occurs on the labellar callus and is of the intermediate type, possessing both glabrous and trichomatous regions. By contrast, although all four species produce lipid secretions, C. meirax lacks an obvious elaiophore. In each case, the secretory tissue is represented by a single-layered epidermis of cuboidal cells (trichomatous and/or atrichomatous). Palisade cells are absent. The secretion may be wax- or oil-like and is usually produced by smooth endoplasmic reticulum (SER). However, in C. meirax, where rough endoplasmic reticulum (RER) predominates, oil accumulates as plastoglobuli within elaioplasts. These plastoglobuli are then discharged into the cytoplasm, forming oil bodies. In some species, oil usually accumulates within vesicles at the plasmalemma or in the periplasmic space before traversing the cell wall and accumulating beneath the cuticle, sometimes with distension of the latter. Gomesa longipes is unusual in its production of a heterogeneous secretion, whereas Vitekorchis excavata is equally remarkable for the protuberances found on the walls of its secretory cells. CONCLUSIONS Anatomically, the secretory tissues of all four species, despite currently being assigned to four different genera, are remarkably similar and indicative of homoplasy. This supports previous investigations of the floral elaiophore in Oncidiinae, which showed that the same elaiophore characters may be shared by different clades, but not always by species of the same genus. Consequently, elaiophores are considered to be of limited value in investigating the phylogeny of this subtribe. Furthermore, floral dimorphism does not greatly modify elaiophore structure in the fertile flowers of Oncidium heteranthum var. album. Based on the presence or absence of well-defined elaiophores, the nature of the secretion and the cell ultrastructure, it is likely that floral oil may be produced in Oncidiinae in one of two ways: by the ER (mainly SER) or by plastids, most notably elaioplasts. Once the oil is discharged into the cytoplasm as oil bodies or oil droplets, there is little difference between the subsequent stages of oil secretion; the oil traversing the cytoplasm (often vesicle-mediated) and cell wall before accumulating beneath the cuticle.
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Affiliation(s)
- Kevin L Davies
- School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK
| | | | - Michał Rawski
- University of Maria Curie-Skłodowska in Lublin, Plac Marii Curie-Skłodowskiej, 2-031 Lublin, Poland
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Blanco MA, Davies KL, Stpiczyńska M, Carlsward BS, Ionta GM, Gerlach G. Floral elaiophores in Lockhartia Hook. (Orchidaceae: Oncidiinae): their distribution, diversity and anatomy. ANNALS OF BOTANY 2013; 112:1775-91. [PMID: 24169595 PMCID: PMC3838557 DOI: 10.1093/aob/mct232] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 08/13/2013] [Indexed: 05/30/2023]
Abstract
BACKGROUND AND AIMS A significant proportion of orchid species assigned to subtribe Oncidiinae produce floral oil as a food reward that attracts specialized bee pollinators. This oil is produced either by glabrous glands (epithelial elaiophores) or by tufts of secretory hairs (trichomal elaiophores). Although the structure of epithelial elaiophores in the Oncidiinae has been well documented, trichomal elaiophores are less common and have not received as much attention. Only trichomal elaiophores occur in the genus Lockhartia, and their distribution and structure are surveyed here for the first time. METHODS Flowers of 16 species of Lockhartia were studied. The location of floral elaiophores was determined histochemically and their anatomical organization and mode of oil secretion was investigated by means of light microscopy, scanning electron microscopy and transmission electron microscopy. KEY RESULTS AND CONCLUSIONS All species of Lockhartia investigated have trichomal elaiophores on the adaxial surface of the labellum. Histochemical tests revealed the presence of lipoidal substances within the labellar trichomes. However, the degree of oil production and the distribution of trichomes differed between the three major groups of species found within the genus. All trichomes were unicellular and, in some species, of two distinct sizes, the larger being either capitate or apically branched. The trichomal cuticle was lamellate, and often appeared distended due to the subcuticular accumulation of oil. The labellar trichomes of the three species examined using transmission electron microscopy contained dense, intensely staining cytoplasm with apically located vacuoles. Oil-laden secretory vesicles fused with the plasmalemma and discharged their contents. Oil eventually accumulated between the cell wall and cuticle of the trichome and contained electron-transparent profiles or droplets. This condition is considered unique to Lockhartia among those species of elaiophore-bearing Oncidiinae studied to date.
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Affiliation(s)
- Mario A. Blanco
- Escuela de Biología, Universidad de Costa Rica, Ciudad Universitaria Rodrigo Facio, Apdo. 11501–2060, San José, Costa Rica; and research associate, Jardín Botánico Lankester, Universidad de Costa Rica, Apdo. 1031–7050 Cartago, Costa Rica
| | - Kevin L. Davies
- School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK
| | | | - Barbara S. Carlsward
- Department of Biological Sciences, Eastern Illinois University, Charleston, IL 61920-3099, USA
| | - Gretchen M. Ionta
- Department of Biology, University of Florida, Gainesville, FL 32611–8526, USA
| | - Günter Gerlach
- Botanischer Garten München-Nymphenburg, Menzinger Strasse 65, 80638 München, Germany
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Stpiczyńska M, Davies KL, Pacek-Bieniek A, Kamińska M. Comparative anatomy of the floral elaiophore in representatives of the newly re-circumscribed Gomesa and Oncidium clades (Orchidaceae: Oncidiinae). ANNALS OF BOTANY 2013; 112:839-854. [PMID: 23884394 PMCID: PMC3747802 DOI: 10.1093/aob/mct149] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 05/14/2013] [Indexed: 05/30/2023]
Abstract
BACKGROUND AND AIMS Recently, molecular approaches have been used to investigate the phylogeny of Oncidiinae. This has resulted in the transfer of taxa previously considered to be species of Oncidium Sw. into Gomesa R. Br. and the re-circumscription of both genera. In this study, the structure of the floral elaiophore (oil gland) is described and compared for Gomesa echinata (Barb. Rodr.) M.W. Chase & N.H. Williams, G. ranifera (Lindl.) M.W. Chase & N.H. Williams, Oncidium amazonicum (Schltr.) M.W. Chase & N.H. Williams and O. oxyceras (Königer & J.G. Weinm.) M.W. Chase & N.H. Williams in order to determine whether phylogenetic revision is supported by differences in its anatomy. METHODS The floral elaiophore structure was examined and compared at three developmental stages (closed bud, first day of anthesis and final stage of anthesis) for all four species using light microscopy, fluorescence microscopy, scanning electron microscopy, transmission electron microscopy and histochemistry. KEY RESULTS In all species investigated, the floral elaiophore occurs on the labellar callus and is of the epithelial type, comprising cuboidal to palisade-like, secretory epidermal cells and a layer of sub-epidermal cells, both tissues enclosing ground parenchyma supplied with collateral vascular bundles and containing idioblasts, often with raphides or phenolic contents. A bi-layered cuticle comprising an outer, lamellate and an inner, reticulate layer is present, and sub-cuticular accumulation of secreted material results in distension of the cuticle. Secretion-filled cavities are present at anthesis in the elaiophore cell walls and, in most species, the outer, tangential walls of the elaiophore have small, peg-like projections that protrude into the cytoplasm. In all taxa examined, the elaiophore organelle complement, especially the smooth endoplasmic reticulum (SER), is typical of lipid-secreting cells. CONCLUSIONS In terms of location, morphology, anatomy and ultrastructure, the floral elaiophores of both Gomesa and Oncidium species examined are very similar, and distinction between these genera is not possible based on elaiophore features alone. Furthermore, many of these elaiophore characters are shared with representatives of other clades of Oncidiinae, including the Ornithocephalus clade. Consequently, elaiophores are considered homoplasious and of limited value in investigating the phylogeny of this subtribe.
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Affiliation(s)
| | - Kevin L. Davies
- School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK
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Sanguinetti A, Buzatto CR, Pedron M, Davies KL, Ferreira PMDA, Maldonado S, Singer RB. Floral features, pollination biology and breeding system of Chloraea membranacea Lindl. (Orchidaceae: Chloraeinae). ANNALS OF BOTANY 2012; 110:1607-21. [PMID: 23071217 PMCID: PMC3503500 DOI: 10.1093/aob/mcs221] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 09/03/2012] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS The pollination biology of very few Chloraeinae orchids has been studied to date, and most of these studies have focused on breeding systems and fruiting success. Chloraea membranacea Lindl. is one of the few non-Andean species in this group, and the aim of the present contribution is to elucidate the pollination biology, functional floral morphology and breeding system in native populations of this species from Argentina (Buenos Aires) and Brazil (Rio Grande do Sul State). METHODS Floral features were examined using light microscopy, and scanning and transmission electron microscopy. The breeding system was studied by means of controlled pollinations applied to plants, either bagged in the field or cultivated in a glasshouse. Pollination observations were made on natural populations, and pollinator behaviour was recorded by means of photography and video. KEY RESULTS Both Argentinean and Brazilian plants were very consistent regarding all studied features. Flowers are nectarless but scented and anatomical analysis indicates that the dark, clavate projections on the adaxial labellar surface are osmophores (scent-producing glands). The plants are self-compatible but pollinator-dependent. The fruit-set obtained through cross-pollination and manual self-pollination was almost identical. The main pollinators are male and female Halictidae bees that withdraw the pollinarium when leaving the flower. Remarkably, the bees tend to visit more than one flower per inflorescence, thus promoting self-pollination (geitonogamy). Fruiting success in Brazilian plants reached 60·78 % in 2010 and 46 % in 2011. Some pollinarium-laden female bees were observed transferring pollen from the carried pollinarium to their hind legs. The use of pollen by pollinators is a rare record for Orchidaceae in general. CONCLUSIONS Chloraea membrancea is pollinated by deceit. Together, self-compatibility, pollinarium texture, pollinator abundance and behaviour may account for the observed high fruiting success. It is suggested that a reappraisal and re-analysis of important flower features in Chloraeinae orchids is necessary.
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Affiliation(s)
- Agustin Sanguinetti
- Laboratorio de Biología del Desarrollo de las Plantas, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EGA Ciudad de Buenos Aires, Argentina
| | - Cristiano Roberto Buzatto
- Universidade Federal do Rio Grande do Sul, Instituto de Biociências, Departamento de Botânica, Programa de Pós-graduação em Botânica, Av. Bento Gonçalves 9500, 91501-970, Porto Alegre, Rio Grande do Sul, Brazil
| | - Marcelo Pedron
- Universidade Federal do Rio Grande do Sul, Instituto de Biociências, Departamento de Botânica, Programa de Pós-graduação em Botânica, Av. Bento Gonçalves 9500, 91501-970, Porto Alegre, Rio Grande do Sul, Brazil
| | - Kevin L. Davies
- School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK
| | - Pedro Maria de Abreu Ferreira
- Universidade Federal do Rio Grande do Sul, Instituto de Biociências, Departamento de Botânica, Programa de Pós-graduação em Botânica, Av. Bento Gonçalves 9500, 91501-970, Porto Alegre, Rio Grande do Sul, Brazil
| | - Sara Maldonado
- Laboratorio de Biología del Desarrollo de las Plantas, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EGA Ciudad de Buenos Aires, Argentina
| | - Rodrigo B. Singer
- Universidade Federal do Rio Grande do Sul, Instituto de Biociências, Departamento de Botânica, Programa de Pós-graduação em Botânica, Av. Bento Gonçalves 9500, 91501-970, Porto Alegre, Rio Grande do Sul, Brazil
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Pacek A, Stpiczyńska M, Davies KL, Szymczak G. Floral elaiophore structure in four representatives of the Ornithocephalus clade (Orchidaceae: Oncidiinae). ANNALS OF BOTANY 2012; 110:809-20. [PMID: 22805528 PMCID: PMC3423815 DOI: 10.1093/aob/mcs158] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Accepted: 05/18/2012] [Indexed: 05/19/2023]
Abstract
BACKGROUND AND AIMS A significant number of species assigned to the Neotropical orchid sub-tribe Oncidiinae reward insect pollinators with oil produced in floral glands termed elaiophores. The latter may be glabrous (epithelial elaiophores) or hirsute (trichomal elaiophores). Although the detailed anatomy and ultrastructure of epithelial elaiophores have been studied for a number of genera, such as Oncidium Sw., Gomesa R. Br. and Trichocentrum Poepp. & Endl., hitherto, trichomal elaiophores have been investigated only for a single species of Oncidiinae, Ornithocephalus ciliatus Lindl. Furthermore, this is the only representative of the Ornithocephalus clade to be investigated to date. Here, an examination is made of the elaiophore anatomy and ultrastructure of a further four species currently assigned to this clade (Ornithocephalus gladiatus Hook., Phymatidium falcifolium Lindl., Zygostates grandiflora (Lindl.) Mansf. and Zygostates lunata Lindl.) and the results compared with those obtained for other Oncidiinae. METHODS Elaiophore structure was examined for all species at three stages of flower development: closed bud, first day of anthesis and final stage of anthesis, using light microscopy, fluorescence microscopy, scanning electron microscopy, transmission electron microscopy and histochemistry. KEY RESULTS Elaiophores of O. gladiatus occur upon the lateral lobes of the labellum and display characters intermediate between those of typical epithelial and trichomal elaiophores, in that they are largely glabrous, consisting mainly of cuboidal epidermal cells, but bear short, unicellular hairs proximally. By contrast, the elaiophores of all the other species investigated occur on the callus and are of the trichomal type. In P. falcifolium, these unicellular hairs are capitate. In all species, oil secretion commenced at the closed floral bud stage. Ultrastructurally, the mainly trichomal elaiophores of the four representatives of the Ornithocephalus clade closely resembled the epithelial elaiophores of other Oncidiinae, in that their cells displayed an organelle complement typical of lipid-secreting cells. However, in some taxa, a number of noteworthy characters were present. For example, the elaiophore cuticle of O. gladiatus and P. falcifolium was bi-layered, the outer layer being lamellate, the inner reticulate. The cuticle of Z. grandiflora and Z. lunata was also lamellate, but here, a reticulate layer was absent. Accumulation of secreted oil resulted in the localized distension of the cuticle. Cuticular cracks and pores, however, were absent from all species. The walls of the secretory cells of Z. grandiflora were also atypical in that they had short protuberances or ingrowths, and contained cavities which are thought to be involved in the secretory process. CONCLUSIONS Of the species investigated, most displayed similar anatomical organization, their trichomal elaiophores occurring on the labellar callus. They, thus, differ from many other members of the Oncidiinae, where epithelial elaiophores are found either on the callus, or on the lateral lobes of the labellum. However, ultrastructurally, all elaiophores, whether those of representatives of the Ornithocephalus clade, or those of other oil-secreting Oncidiinae, possessed a similar complement of organelles, regardless of whether the elaiophores were trichomal or epithelial. In view of the latter, and the similar chemical composition of oils derived from all Oncidiinae investigated to date, it is probable that position and type of elaiophore, and possibly the structure of the overlying cuticle, play an important role in pollinator selection in these oil-secreting orchids.
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Affiliation(s)
- Agata Pacek
- University of Life Sciences, Akademicka 15, 20-950 Lublin, Poland
| | | | - Kevin L. Davies
- School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK
- For correspondence. E-mail
| | - Grażyna Szymczak
- Maria Curie-Skłodowska University Botanic Garden, Sławinkowska 3, 20-810 Lublin, Poland
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Buzatto CR, Davies KL, Singer RB, Pires dos Santos R, van den Berg C. A comparative survey of floral characters in Capanemia Barb. Rodr. (Orchidaceae: Oncidiinae). ANNALS OF BOTANY 2012; 109:135-144. [PMID: 21937482 PMCID: PMC3241572 DOI: 10.1093/aob/mcr241] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 08/12/2011] [Indexed: 05/31/2023]
Abstract
BACKGROUND AND AIMS Capanemia Barb. Rodr. comprises seven species that mostly inhabit the Brazilian Atlantic Rain Forest domain. The genus currently consists of two sections: Capanemia Cogn. and Planifolia Pabst, distinguished on the basis of leaf shape. We compare the floral morphology and anatomy of all species to determine whether separation into sections is supported by floral characters. METHODS Both fresh flowers and herbarium specimens were investigated, and column and pollinarium features, together with the presence or absence of floral rewards, recorded. Anatomical features were examined using both light microscopy and scanning electron microscopy. KEY RESULTS AND CONCLUSIONS With the sole exception of Capanemia therezae, all species shared a distinctive set of floral characters. Flowers were mostly white or yellowish-white and fragrant, and column wings were positioned parallel to the labellum, concealing the stigmatic cavity. Pollinaria had proportionally long tegular stipes and clavate to reniform pollinia, whereas the labellum possessed a conspicuous indument of trichomes, but was devoid of nectar or any other secretion that might function as a food-reward. Capanemia therezae, however, was exceptional in having greenish, unscented flowers with short, rounded and divergent column wings and an exposed stigmatic cavity. Its pollinaria had proportionally short tegular stipes and round pollinia, whereas the labellum lacked trichomes. Droplets of nectar were evident on the adaxial surface of the labellum, adjacent to the callus. Floral features did not support the currently accepted sectional division of Capanemia. If ongoing phylogenetic studies demonstrate that both sections are indeed monophyletic, then these taxa should be distinguished solely on the basis of foliar features.
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Affiliation(s)
- Cristiano Roberto Buzatto
- Universidade Federal do Rio Grande do Sul, Instituto de Biociências, Departamento de Botânica, Programa de Pós-graduação em Botânica, Av. Bento Gonçalves 9500, RS 91501-970, Porto Alegre, Rio Grande do Sul, Brazil.
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Pansarin ER, Pansarin LM. Reproductive biology of Trichocentrum pumilum: an orchid pollinated by oil-collecting bees. PLANT BIOLOGY (STUTTGART, GERMANY) 2011; 13:576-581. [PMID: 21668598 DOI: 10.1111/j.1438-8677.2010.00420.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The reproductive biology, reward production and pollination mechanism of Trichocentrum pumilum were studied in a gallery forest in the interior of the State of São Paulo, southeast Brazil. The floral visitors and pollination mechanism were recorded, and experimental pollinations were carried out in order to determine the breeding system of this species. Trichocentrum pumilum blooms in spring. Each paniculate inflorescence bears an average of 85 flowers that present a central yellow callus and finger-like trichomes on the lateral lobes of the lip. A lipoidal substance is produced and stored among these trichomes. In the studied population, T. pumilum is exclusively visited and pollinated by two bee species (Tetrapedia diversipes and Lophopedia nigrispinis). Pollinaria are deposited on mouthparts of bees during collection of the lipoidal substance from the lateral lobes of the labellum. Trichocentrum pumilum is self-incompatible and pollinator-limited. Natural fruit set was low (9%, compared to 45% in experimentally cross-pollinated flowers). Potentially viable seed exceed 97% in fruits obtained through cross-pollination and in natural conditions (open pollination).
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Affiliation(s)
- E R Pansarin
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras, Universidade de São Paulo, Av. Bandeirantes 3900, Ribeirão Preto, SP, Brazil.
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