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Francisco A, Ascensão L. Osmophore Structure and Labellum Micromorphology in Ophrys speculum (Orchidaceae): New Interpretations of Floral Features and Implications for a Specific Sexually Deceptive Pollination Interaction. PLANTS (BASEL, SWITZERLAND) 2024; 13:1413. [PMID: 38794483 PMCID: PMC11125028 DOI: 10.3390/plants13101413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 05/12/2024] [Accepted: 05/14/2024] [Indexed: 05/26/2024]
Abstract
Pollination by sexual deception specifically attracts male insects, through the floral scent and particular morphological features of the flower that serve as visual and tactile stimuli. The unique bond between the Ophrys speculum orchid and the male Dasyscolia ciliata wasp primarily stems from a few distinctive semiochemicals that mimic the female wasp's sex pheromone, although the floral scent comprises a variety of compounds. An osmophore producing highly volatile compounds has been documented in four close relatives of O. speculum and is now being also investigated in this species. Given the existing debates regarding the structure of the labellum and stigmatic cavity in O. speculum, this study details their micromorphology. Additionally, comparisons of O. speculum flowers and female D. ciliata wasps under stereomicroscopy and scanning electron microscopy are conducted to seek new evidence of visual and tactile mimicry. The findings confirm that (i) an osmophore is present at the apical margin of the labellum in O. speculum flowers; (ii) the labellum features a distinct basal field homologous to those found in other Ophrys species; and (iii) the basal labellum region closely mimics the female wasp's thorax and wings. The implications of these novel floral features are discussed within an evolutionary context.
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Affiliation(s)
- Ana Francisco
- Centro de Estudos do Ambiente e do Mar (CESAM Lisboa), Faculdade de Ciências da Universidade de Lisboa (FCUL), C2, Campo Grande, 1749-016 Lisboa, Portugal
| | - Lia Ascensão
- Centro de Estudos do Ambiente e do Mar (CESAM Lisboa), Faculdade de Ciências da Universidade de Lisboa (FCUL), C2, Campo Grande, 1749-016 Lisboa, Portugal
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Yuan B, Yuan JK, Huang CG, Lian JR, Li YH, Fan XM, Yuan DY. Pseudopollen in Camellia oleifera and its implications for pollination ecology and taxonomy. FRONTIERS IN PLANT SCIENCE 2022; 13:1032187. [PMID: 36466242 PMCID: PMC9712735 DOI: 10.3389/fpls.2022.1032187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 10/24/2022] [Indexed: 05/24/2023]
Abstract
BACKGROUND AND AIMS In 1997, Tsou described the special differentiation of the connective tissues of some species of Theaceae to produce single-celled powders with unique patterns called pseudopollen. The purpose of this study was to investigate the morphological structure of the pseudopollen of Camellia oleifera (Theaceae) and to study the morphology of pseudopollen in seven other Camellia species. METHODS Scanning electron microscopy, paraffin section, light microscopy, transmission electron microscopy, histochemistry. KEY RESULT C. oleifera pseudopollen was similar to normal pollen in macroscopic morphology but different microscopically. The normal pollen was starch-rich and yellow, with mostly reticulate exine ornamentation. In contrast, the pseudopollen was a white powder, single-celled and rich in protein, with parallel unbranched ridge lines on the outer wall, and originated from the parenchyma of the connective tissues. There are also differences in the micro-characteristics of normal and pseudopollen among different species in Camellia. CONCLUSION There are great differences in morphological structure between C. oleifera and other species in Camellia normal pollen and pseudopollen; these results may indicate that the pseudopollen can be used as a taxonomic basis for Camellia, and the macroscopic similarity between pseudopollen and pollen and histochemical characteristics of pseudopollen can be a pollination strategy.
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Affiliation(s)
- Bin Yuan
- Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, Changsha, China
- Key Laboratory of Non-Wood Forest Products of State Forestry Administration, Central South University of Forestry and Technology, Changsha, China
| | - Jing-Kun Yuan
- Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, Changsha, China
- Key Laboratory of Non-Wood Forest Products of State Forestry Administration, Central South University of Forestry and Technology, Changsha, China
| | - Cheng-Gong Huang
- Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, Changsha, China
- Key Laboratory of Non-Wood Forest Products of State Forestry Administration, Central South University of Forestry and Technology, Changsha, China
| | - Jia-Rui Lian
- Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, Changsha, China
- Key Laboratory of Non-Wood Forest Products of State Forestry Administration, Central South University of Forestry and Technology, Changsha, China
| | - Yi-Huan Li
- Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, Changsha, China
- Key Laboratory of Non-Wood Forest Products of State Forestry Administration, Central South University of Forestry and Technology, Changsha, China
| | - Xiao-Ming Fan
- Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, Changsha, China
- Key Laboratory of Non-Wood Forest Products of State Forestry Administration, Central South University of Forestry and Technology, Changsha, China
| | - De-Yi Yuan
- Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, Changsha, China
- Key Laboratory of Non-Wood Forest Products of State Forestry Administration, Central South University of Forestry and Technology, Changsha, China
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Huang H, Kuo YW, Chuang YC, Yang YP, Huang LM, Jeng MF, Chen WH, Chen HH. Terpene Synthase-b and Terpene Synthase-e/f Genes Produce Monoterpenes for Phalaenopsis bellina Floral Scent. FRONTIERS IN PLANT SCIENCE 2021; 12:700958. [PMID: 34335666 PMCID: PMC8318001 DOI: 10.3389/fpls.2021.700958] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 06/21/2021] [Indexed: 05/25/2023]
Abstract
Orchids are the most species-rich plants and highly interactive with pollinators via visual or olfactory cues. Biosynthesis and emission of volatile organic compounds (VOCs) to the atmosphere facilitate the olfactory cues and ensure successful pollination. Phalaenopsis bellina is a scented orchid with monoterpenes as major VOCs, comprising linalool, geraniol, and their derivatives. Comparative transcriptomics analysis identified four terpene synthase-b (TPS-b) genes and two TPS-e/f genes with differential gene expression between scented and scentless Phalaenopsis species. Here, we confirmed their differential expression between scented and scentless Phalaenopsis orchids and excluded one TPS-b candidate. We analyzed the temporal and spatial expression and functionally characterized these TPSs. Both TPS-b and TPS-e/f genes showed an increased expression on blooming day or 3 days post-anthesis (D + 3) before the optimal emission of floral scent on D + 5, with especially high expression of PbTPS5 and PbTPS10. The TPS-b genes are expressed exclusively in reproductive organs, whereas the TPS-e/f genes are expressed in both reproductive and vegetative organs. In planta functional characterization of both PbTPS5 and PbTPS10 in tobacco and scentless Phalaenopsis plants did not produce terpenoids. Further ectopic expression in scented Phalaenopsis cultivar P. I-Hsin Venus showed that linalool was the main product, with PbTPS10 displaying 3-fold higher activity than PbTPS5. On in vitro enzyme assay with purified recombinant TPS-b proteins ectopically expressed in Escherichia coli, geraniol was the product catalyzed by PbTPS5 and PbTPS9. PbTPS3 was a linalool/(β)-cis-ocimene synthase and PbTPS4 a linalool synthase. In conclusion, both TPS-b and TPS-e/f enzymes orchestrated floral monoterpene biosynthesis in P. bellina.
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Affiliation(s)
- Hsin Huang
- Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Yi-Wei Kuo
- Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Yu-Chen Chuang
- Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Ya-Ping Yang
- Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Li-Min Huang
- Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Mei-Fen Jeng
- Orchid Research and Development Center, National Cheng Kung University, Tainan, Taiwan
| | - Wen-Huei Chen
- Orchid Research and Development Center, National Cheng Kung University, Tainan, Taiwan
| | - Hong-Hwa Chen
- Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan
- Orchid Research and Development Center, National Cheng Kung University, Tainan, Taiwan
- Institute of Tropical Plant and Microbial Sciences, National Cheng Kung University, Tainan, Taiwan
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Kowalkowska AK, Turzyński S, Kozieradzka-Kiszkurno M, Wiśniewska N. Floral structure of two species of Bulbophyllum section Cirrhopetalum Lindl.: B. weberi Ames and B. cumingii (Lindl.) Rchb. f. (Bulbophyllinae Schltr., Orchidaceae). PROTOPLASMA 2017; 254:1431-1449. [PMID: 27798718 PMCID: PMC5376396 DOI: 10.1007/s00709-016-1034-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 10/10/2016] [Indexed: 05/25/2023]
Abstract
Flowers of Bulbophyllum weberi and B. cumingii are characterized by fly-pollinated features. The secretory activity was described in dorsal sepals in both species (putative osmophores), petals in B. weberi (possible osmophores) and adaxial surface of lips in both species. In the cells of dorsal sepals and petals of B. weberi proteins, dihydroxyphenols, lipids and starch grains were detected, in lateral sepals-lipids. Whereas in dorsal sepal of B. cumingii only lipids and starch grains were noted, in lateral sepals-proteins and dihydroxyphenols and in petals-proteins and starch grains. The lips in both species differed histochemically and ultrastructurally. The epidermal cells of lip groove in B. weberi contained lipids, proteins, starch grains in cytoplasm, dihydroxyphenols in vacuoles and pectic acids/mucilage on surface. Whereas in B. cumingii-few lipids, starch grains, no proteins, no dihydroxyphenols and no mucilage were noted. Ultrastructurally, in B. weberi, the secretory material was present on surface and vesicles building into plasmalemma, while in B. cumingii-cell wall ingrowths and microchannels in cuticle. The osmiophilic irregular materials and globular, osmiophilic globules in B. weberi are probably tannin-like materials. For the first time, we described the cell wall ingrowths in Bulbophyllum species: in lip of B. cumingii and petals of B. weberi.
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Affiliation(s)
- Agnieszka K Kowalkowska
- Department of Plant Cytology and Embryology, University of Gdańsk, Wita Stwosza 59, 80-308, Gdańsk, Poland.
| | - Sławomir Turzyński
- Department of Plant Cytology and Embryology, University of Gdańsk, Wita Stwosza 59, 80-308, Gdańsk, Poland
| | | | - Natalia Wiśniewska
- Department of Plant Cytology and Embryology, University of Gdańsk, Wita Stwosza 59, 80-308, Gdańsk, Poland
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Płachno BJ, Stpiczyńska M, Davies KL, Świątek P, de Miranda VFO. Floral ultrastructure of two Brazilian aquatic-epiphytic bladderworts: Utricularia cornigera Studnička and U. nelumbifolia Gardner (Lentibulariaceae). PROTOPLASMA 2017; 254:353-366. [PMID: 26945989 PMCID: PMC5216069 DOI: 10.1007/s00709-016-0956-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 02/22/2016] [Indexed: 05/11/2023]
Abstract
Utricularia cornigera and Utricularia nelumbifolia are giant, aquatic-epiphytic species of carnivorous bladderwort from southeastern Brazil that grow in the central 'urns' of bromeliads. Both species have large, colourful flowers. The main aim of our study is to ascertain whether the prominent floral palate of U. cornigera and U. nelumbifolia functions as an unguentarius-i.e. an organ that bears osmophores. Floral tissues of both species were investigated using light microscopy, scanning electron microscopy, transmission electron microscopy and histochemistry. Floral palates of U. cornigera and U. nelumbifolia provide clear visual signals for pollinating insects. In both species, the palate possesses diverse micro-morphology, comprising unicellular, conical to villiform papillae and multicellular, uniseriate, glandular trichomes that frequently display terminal branching. The most characteristic ultrastructural feature of these papillae was the presence of relatively large, polymorphic plastids (chromoplasts) containing many plastoglobuli. Similar plastids are known to occur in the fragrance-producing (osmophores) and oil-producing (elaiophores) tissues of several orchid species. Thus, these palate papillae may play a key role in providing the olfactory stimulus for the attraction of insect pollinators. Nectariferous trichomes were observed in the floral spurs of both species, and in U. nelumbifolia, free nectar was also recorded. The location, micro-morphology, anatomy and ultrastructure of the floral palate of the two species investigated may thus indicate that the palate functions as an unguentarius. Furthermore, the flowers of these taxa, like those of U. reniformis, have features consistent with bee pollination.
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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, University of Warsaw, Botanic Garden Al. Ujazdowskie 4, 00-478, Warsaw, Poland
| | - Kevin L Davies
- School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK
| | - Piotr Świątek
- Department of Animal Histology and Embryology, University of Silesia, 9 Bankowa St., 40-007, Katowice, Poland
| | - Vitor Fernandes Oliveira de Miranda
- Departamento de Biologia Aplicada à Agropecuária, Faculdade de Ciências Agrárias e Veterinárias, Univ Estadual Paulista-UNESP, Câmpus Jaboticabal, São Paulo, Brazil
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Płachno BJ, Stpiczyńska M, Świątek P, Davies KL. Floral micromorphology of the Australian carnivorous bladderwort Utricularia dunlopii, a putative pseudocopulatory species. PROTOPLASMA 2016; 253:1463-1473. [PMID: 26497694 PMCID: PMC5069315 DOI: 10.1007/s00709-015-0900-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Accepted: 10/16/2015] [Indexed: 05/11/2023]
Abstract
Flowers of sexually deceptive taxa generally possess a set of morphological and physiological characters that mimic their insect pollinators. These characters often include a specific insect-like floral configuration, together with scent glands (osmophores) that produce fragrances which chemically resemble insect sex pheromones. Furthermore, these flowers tend not to produce pollinator food rewards. According to some authors, flowers of the Australian bladderwort Utricularia dunlopii (and species of the Utricularia capilliflora complex) resemble insects, and pollination perhaps occurs by pseudocopulation. The aims of this paper are to compare the structure and distribution of floral glandular trichomes in the Australian carnivorous plant U. dunlopii with those of closely related species assigned to the same section and to discuss their putative function. Floral tissues of U. dunlopii P. Taylor, Utricularia paulinae Lowrie, Utricularia dichotoma Labill. and Utricularia uniflora R.Br. (section Pleiochasia) were investigated using light microscopy, scanning electron microscopy, transmission electron microscopy and histochemistry. In U. dunlopii, two long, erect, filiform appendages arising from the upper lip of the corolla, together with three arising from the lower lip, bear numerous glandular trichomes that may function as osmophores. In other species, such as U. uniflora and U. paulinae, glandular papillae on the corolla palate may also function as osmophores. The floral anatomical and morphological organisation of U. dunlopii differs from that of the other investigated species, indicating that its insect pollinators are also likely to differ. Morphological and ultrastructural observations, while generally contributing to our understanding of the flower of U. dunlopii, do not refute the possibility that pollination here may occur by pseudocopulation. Further field-based investigations, however, are now necessary to test this hypothesis.
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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
- University of Warsaw, Faculty of Biology, Botanic Garden Al. Ujazdowskie 4, 00-478, Warsaw, Poland
| | - Piotr Świątek
- Department of Animal Histology and Embryology, University of Silesia, 9 Bankowa St., 40-007, Katowice, Poland
| | - Kevin L Davies
- School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK
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Weak trophic links between a crab-spider and the effective pollinators of a rewardless orchid. ACTA OECOLOGICA 2015. [DOI: 10.1016/j.actao.2014.11.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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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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