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Hao N, Yao H, Suzuki M, Li B, Wang C, Cao J, Fujiwara T, Wu T, Kamiya T. Novel lignin-based extracellular barrier in glandular trichome. NATURE PLANTS 2024; 10:381-389. [PMID: 38374437 DOI: 10.1038/s41477-024-01626-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 01/16/2024] [Indexed: 02/21/2024]
Abstract
Successful biochemical reactions in organisms necessitate compartmentalization of the requisite components. Glandular trichomes (GTs) act as compartments for the synthesis and storage of specialized compounds. These compounds not only are crucial for the survival of plants under biotic and abiotic stresses but also have medical and commercial value for humans. However, the mechanisms underlying compartmentalization remain unclear. Here we identified a novel structure that is indispensable for the establishment of compartments in cucumber GTs. Silica, a specialized compound, is deposited on the GTs and is visible on the surface of the fruit as a white powder, known as bloom. This deposition provides resistance against pathogens and prevents water loss from the fruits1. Using the cucumber bloomless mutant2, we discovered that a lignin-based cell wall structure in GTs, named 'neck strip', achieves compartmentalization by acting as an extracellular barrier crucial for the silica polymerization. This structure is present in the GTs of diverse plant species. Our findings will enhance the understanding of the biosynthesis of unique compounds in trichomes and provide a basis for improving the production of compounds beneficial to humans.
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Affiliation(s)
- Ning Hao
- College of Horticulture/Yuelu Mountain Laboratory of Hunan Province, Hunan Agricultural University, Changsha, China
- Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Hongxin Yao
- College of Horticulture/Yuelu Mountain Laboratory of Hunan Province, Hunan Agricultural University, Changsha, China
| | - Michio Suzuki
- Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Baohai Li
- MOE Key Laboratory of Environment Remediation and Ecological Health, College of Environmental and Resource Science, Zhejiang University, Hangzhou, China
| | - Chunhua Wang
- College of Horticulture/Yuelu Mountain Laboratory of Hunan Province, Hunan Agricultural University, Changsha, China
| | - Jiajian Cao
- College of Horticulture/Yuelu Mountain Laboratory of Hunan Province, Hunan Agricultural University, Changsha, China
| | - Toru Fujiwara
- Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Tao Wu
- College of Horticulture/Yuelu Mountain Laboratory of Hunan Province, Hunan Agricultural University, Changsha, China.
| | - Takehiro Kamiya
- Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan.
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2
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Pyke GH, Ren ZX. Floral nectar production: what cost to a plant? Biol Rev Camb Philos Soc 2023; 98:2078-2090. [PMID: 37461187 DOI: 10.1111/brv.12997] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 05/29/2023] [Accepted: 06/30/2023] [Indexed: 11/07/2023]
Abstract
Floral nectar production is central to plant pollination, and hence to human wellbeing. As floral nectar is essentially a solution in water of various sugars, it is likely a valuable plant resource, especially in terms of energy, with plants experiencing costs/trade-offs associated with its production or absorption and adopting mechanisms to regulate nectar in flowers. Possible costs of nectar production may also influence the evolution of nectar volume, concentration and composition, of pollination syndromes involving floral nectar, and the production of some crops. There has been frequent agreement that costs of floral nectar production are significant, but relevant evidence is scant and difficult to interpret. Convincing direct evidence comes from experimental studies that relate either enhanced nectar sugar production (through repeated nectar removal) to reduced ability to produce seeds, or increased sugar availability (through absorption of additional artificial nectar) to increased seed production. Proportions of available photosynthate allocated by plants to nectar production may also indicate nectar cost. However, such studies are rare, some do not include treatments of all (or almost all) flowers per plant, and all lack quantitative cost-benefit comparisons for nectar production. Additional circumstantial evidence of nectar cost is difficult to interpret and largely equivocal. Future research should repeat direct experimental approaches that relate reduced or enhanced nectar sugar availability for a plant with consequent ability to produce seeds. To avoid confounding effects of inter-flower resource transfer, each plant should experience a single treatment, with treatment of all or almost all flowers per plant. Resource allocation by plants, pathways used for resource transfer, and the locations of resource sources and sinks should also be investigated. Future research should also consider extension of nectar cost into other areas of biology. For example, evolutionary models of nectar production are rare but should be possible if plant fitness gains and costs associated with nectar production are expressed in the same currency, such as energy. It should then be possible to understand observed nectar production for different plant species and pollination syndromes involving floral nectar. In addition, potential economic benefits should be possible to assess if relationships between nectar production and crop value are evaluated.
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Affiliation(s)
- Graham H Pyke
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
- School of Natural Sciences, Macquarie University, Balaclava Rd, North Ryde, 2113, New South Wales, Australia
| | - Zong-Xin Ren
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
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Zhang HP, Wen SJ, Wang H, Ren ZX. Floral nectar reabsorption and a sugar concentration gradient in two long-spurred Habenaria species (Orchidaceae). BMC PLANT BIOLOGY 2023; 23:331. [PMID: 37349723 DOI: 10.1186/s12870-023-04344-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Accepted: 06/11/2023] [Indexed: 06/24/2023]
Abstract
BACKGROUND Floral nectar is the most common reward flowers offered to pollinators. The quality and quantity of nectar produced by a plant species provide a key to understanding its interactions with pollinators and predicting rates of reproductive success. However, nectar secretion is a dynamic process with a production period accompanied or followed by reabsorption and reabsorption remains an understudied topic. In this study, we compared nectar volume and sugar concentration in the flowers of two long-spurred orchid species, Habenaria limprichtii and H. davidii (Orchidaceae). We also compared sugar concentration gradients within their spurs and rates of reabsorption of water and sugars. RESULTS Both species produced diluted nectar with sugar concentrations from 17 to 24%. Analyses of nectar production dynamics showed that as flowers of both species wilted almost all sugar was reabsorbed while the original water was retained in their spurs. We established a nectar sugar concentration gradient for both species, with differences in sugar concentrations at their spur's terminus and at their spur's entrance (sinus). Sugar concentration gradient levels were 1.1% in H. limprichtii and 2.8% in H. davidii, both decreasing as flowers aged. CONCLUSION We provided evidence for the reabsorption of sugars but not water occurred in wilted flowers of both Habenaria species. Their sugar concentration gradients vanished as flowers aged suggesting a slow process of sugar diffusion from the nectary at the spur's terminus where the nectar gland is located. The processes of nectar secretion/reabsorption in conjunction with the dilution and hydration of sugar rewards for moth pollinators warrant further study.
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Affiliation(s)
- Hai-Ping Zhang
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Shi-Jia Wen
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
- College of Forestry, Hainan University, Haikou, 570228, China
- Jiangxi Key Laboratory of Plant Resources and Biodiversity, Jingdezhen University, Jingdezhen, 334000, China
| | - Hong Wang
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.
- University of Chinese Academy of Sciences, Beijing, China.
- Yunnan Lijiang Forest Biodiversity Observation and Research Station, Lijiang, 674100, China.
| | - Zong-Xin Ren
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.
- University of Chinese Academy of Sciences, Beijing, China.
- Yunnan Lijiang Forest Biodiversity Observation and Research Station, Lijiang, 674100, China.
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Arévalo-Rodrigues G, de Barros F, Davis AR, Cardoso-Gustavson P. Floral glands in myophilous and sapromyophilous species of Pleurothallidinae (Epidendroideae, Orchidaceae)-osmophores, nectaries, and a unique sticky gland. PROTOPLASMA 2021; 258:1061-1076. [PMID: 33619653 DOI: 10.1007/s00709-021-01624-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 02/12/2021] [Indexed: 06/12/2023]
Abstract
Pleurothallidinae orchids have been the focus of many multidisciplinary studies due to their challenging systematics and taxonomy. The synapomorphies already recognized in the group are mostly related to floral characters, the last proposed being the occurrence of alkanes in the floral fragrance. The composition of the floral bouquet varied significantly among the studied species, leading us to hypothesize that the variations in volatiles emitted could be linked to the structure of osmophores, especially when comparing the myophilous and sapromyophilous pollination syndromes. Sepals and labellum at different developmental stages of seven Brazilian Pleurothallidinae species were examined using light, scanning, and transmission electron microscopy. Nectar reabsorption was assessed by Lucifer Yellow CH tracer and imaged under confocal microscopy. Nectaries were restricted to the labellum of the myophilous species, whereas osmophores occurred in the dorsal and/or lateral sepals, varying according to species. In the sapromyophilous species, floral nectaries were not detected and osmophores were restricted to the labellum. Osmophore structure was correlated with the volatiles emitted, being the trichome osmophores notably present on the sepals of both myophilous species that possess nectaries. For the first time, we demonstrated reabsorption of the released nectar in Pleurothallidinae and the occurrence of a unique gland named sticky-exudate glands, which occurred in the lateral sepals and labellum of Echinosepala aspasicensis, a sapromyophilous species, that released a heterogeneous exudate composed of polysaccharides and lipids. Similar glands have been reported in Bulbophyllum, highlighting the convergence between both groups.
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Affiliation(s)
- Gustavo Arévalo-Rodrigues
- Programa de Pós-Graduação em Biodiversidade Vegetal e Meio Ambiente, Instituto de Botânica, São Paulo, SP, 04301-902, Brazil.
| | - Fábio de Barros
- Instituto de Botânica, Núcleo de Pesquisa Orquidário do Estado, São Paulo, SP, 04301-902, Brazil
| | - Arthur R Davis
- Department of Biology, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada
| | - Poliana Cardoso-Gustavson
- Programa de Pós-Graduação em Biodiversidade Vegetal e Meio Ambiente, Instituto de Botânica, São Paulo, SP, 04301-902, Brazil
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5
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Machado SR, Rodrigues TM. Apoplasmic barrier in the extrafloral nectary of Citharexylum myrianthum (Verbenaceae). PLANTA 2021; 254:19. [PMID: 34215938 DOI: 10.1007/s00425-021-03663-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 06/14/2021] [Indexed: 06/13/2023]
Abstract
The cytological changes underlying the formation of an apoplasmic barrier in the multi-layered extrafloral nectaries of Citharexylum myrianthum are compatible with the synthesis, transport and deposition of suberin. In terms of ontogenesis and function, the intermediate layers of these nectaries are homologous with the stalks of nectar-secreting trichomes. Anticlinal cell wall impregnations are common in trichomatic nectaries and their functions as endodermis-like barriers have been discussed because of possible direct effects on the nectary physiology, mainly in the nectar secretion and resorption. However, the cytological events linked to nectary wall impregnations remain little explored. This study documents the ontogenesis and the fine structure of the EFN cells, and cytological events linked to the wall impregnations of multi-layered extrafloral nectaries (EFNs) in Citharexylum myrianthum Cham. (Verbenaceae). EFNs are patelliform, and differentiated into (a) a multicellular foot, which is compound in structure and vascularised with phloem strands, (b) a bi-layered intermediate region with thickened cell walls and (c) a single-layered secretory region with palisade-like cells. EFNs are protodermal in origin, starting with a single protodermal cell and ending with the complex, multi-layered structure. The cell wall impregnations first appear in the very young EFN and increase towards maturity. Lipid patches (assumed to be suberin) are deposited on the inner faces of the primary walls, first along the anticlinal walls and then extend to the periclinal walls. On both walls, plasmodesmata remain apparently intact during the maturation of the EFNs. In the peripheral cytoplasm there are abundant polymorphic plastids, well-developed Golgi bodies often close to rough endoplasmic reticulum profiles, mitochondria and polyribosomes. Cytological events linked to the wall impregnations are consistent with suberin synthesis, transport and deposition. Our findings offer new insights into the structure-properties of specialised nectary cell walls and so should contribute to our knowledge of the physiological and protective roles of this structure in nectar glands.
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Affiliation(s)
- Silvia Rodrigues Machado
- Centre of Electron Microscopy (CME), Institute of Biosciences of Botucatu (IBB), São Paulo State University (UNESP), Botucatu, São Paulo, Brazil.
| | - Tatiane Maria Rodrigues
- Department of Biostatistics, Plant Biology, Parasitology and Zoology, Institute of Biosciences of Botucatu (IBB), São Paulo State University (UNESP), Botucatu, São Paulo, Brazil
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6
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Salvage of floral resources through re-absorption before flower abscission. Sci Rep 2020; 10:15960. [PMID: 32994459 PMCID: PMC7524801 DOI: 10.1038/s41598-020-72994-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 09/03/2020] [Indexed: 11/24/2022] Open
Abstract
Plants invest floral resources, including nectar and pigment, with likely consequent reproductive costs. We hypothesized that plants, whose flowers abscise with age, reabsorb nectar and pigment before abscission. This was tested with flowers of Rhododendron decorum, which has large, conspicuous white flowers that increasingly abscise corollas as flowers age. As this species is pollinated by bees, we also hypothesized that nectar concentration would be relatively high (i.e., > 30% wt/vol) and petals would contain UV-absorbing pigment. Floral nectar volume and concentration were sampled on successive days until abscission (up to ten days old, peak at five days) and for sub-sample of four-day-old flowers. Flowers just abscised were similarly sampled. Flower colours were measured using a modified camera, with recordings of spectral reflectance for abscised and open non-abscised flowers. Pigment content was summed values of red, green, blue channels of false color photos. As expected, flowers reabsorbed almost all nectar before abscission, separately reabsorbing nectar-sugar and nectar-water, and petals contained UV-absorbing pigment. However, flowers did not reabsorb pigment and nectar-concentration was < 30% wt/vol. That flowers reabsorb nectar, not pigment, remains unexplained, though possibly pigment reabsorption is uneconomical. Understanding floral resource reabsorption therefore requires determination of biochemical mechanisms, plus costs/benefits for individual plants.
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Borghi M, Fernie AR. Outstanding questions in flower metabolism. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:1275-1288. [PMID: 32410253 DOI: 10.1111/tpj.14814] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/29/2020] [Accepted: 05/05/2020] [Indexed: 06/11/2023]
Abstract
The great diversity of flowers, their color, odor, taste, and shape, is mostly a result of the metabolic processes that occur in this reproductive organ when the flower and its tissues develop, grow, and finally die. Some of these metabolites serve to advertise flowers to animal pollinators, other confer protection towards abiotic stresses, and a large proportion of the molecules of the central metabolic pathways have bioenergetic and signaling functions that support growth and the transition to fruits and seeds. Although recent studies have advanced our general understanding of flower metabolism, several questions still await an answer. Here, we have compiled a list of open questions on flower metabolism encompassing molecular aspects, as well as topics of relevance for agriculture and the ecosystem. These questions include the study of flower metabolism through development, the biochemistry of nectar and its relevance to promoting plant-pollinator interaction, recycling of metabolic resources after flowers whiter and die, as well as the manipulation of flower metabolism by pathogens. We hope with this review to stimulate discussion on the topic of flower metabolism and set a reference point to return to in the future when assessing progress in the field.
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Affiliation(s)
- Monica Borghi
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam, 14476, Germany
| | - Alisdair R Fernie
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam, 14476, Germany
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8
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Giampaoli P, Fernandes FF, Tavares AR, Domingos M, Cardoso-Gustavson P. Fluorescence emission spectra of target chloroplast metabolites (flavonoids, carotenoids, lipofuscins, pheophytins) as biomarkers of air pollutants and seasonal tropical climate. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:25363-25373. [PMID: 32347483 DOI: 10.1007/s11356-020-08646-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 03/27/2020] [Indexed: 06/11/2023]
Abstract
Chloroplasts have luminescent metabolites-chlorophyll being the most known one-whose fluorescence emission may be a useful tool to assess the physiological status of the plant. Some antioxidants (flavonoids and carotenoids), and byproducts of membrane rupture (lipofuscins) and chlorophyll degradation (pheophytins), are chloroplasts' fluorescent metabolites directly involved in plant response to environmental stressors and pollutants and may act as a biomarker of stress. Here we hypothesized that climatic variations and air pollutants induce alterations in the emission profile of chloroplasts' fluorescent metabolites in Tillandsia usneoides (Bromeliaceae). To test this hypothesis, an active biomonitoring study was performed during 2 years in five polluted sites located at the Metropolitan Region of Campinas (São Paulo State, Brazil), aiming to identify target chloroplasts' fluorescent metabolites acting as biomarkers of environmental stress. In situ identification and quantification of the intensity of the fluorescence emission from target metabolites (flavonoids, carotenoids, lipofuscins, and pheophytins) were performed by the observation of fresh leaf sections under confocal laser scanning microscopy. Changes in the profile of fluorescence emission were correlated with local climate and air pollution data. The fluorescence emissions of flavonoids and carotenoids varied seasonally, with significant influence of rainfall and NO2. Our results expand the use of T. usneoides as a bioindicator by using alterations in the fluorescence emission profile of chloroplast metabolites. This application may be especially interesting for NO2 biomonitoring.
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Affiliation(s)
- Patricia Giampaoli
- Programa de Pós-Graduação em Biodiversidade Vegetal e Meio Ambiente, Instituto de Botânica, Av. Miguel Stefano 3687, São Paulo, 04301-902, Brazil
| | - Francine Faia Fernandes
- Programa de Pós-Graduação em Biodiversidade Vegetal e Meio Ambiente, Instituto de Botânica, Av. Miguel Stefano 3687, São Paulo, 04301-902, Brazil
| | | | - Marisa Domingos
- Instituto de Botânica, Av. Miguel Stefano 3687, São Paulo, 04301-902, Brazil
| | - Poliana Cardoso-Gustavson
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Rua Arcturus 03, São Bernardo do Campo, 09606-070, Brazil.
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9
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Park S, Scheffler J, Scheffler B, Cantrell CL, Pauli CS. Chemical defense responses of upland cotton, Gossypium hirsutum L. to physical wounding. PLANT DIRECT 2019; 3:e00141. [PMID: 31245779 PMCID: PMC6589528 DOI: 10.1002/pld3.141] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 04/24/2019] [Accepted: 04/28/2019] [Indexed: 05/04/2023]
Abstract
Upland cotton (Gossypium hirsutum L.) produces terpenoid aldehydes (TAs) that protect the plant from microbial and insect infestations. Foliar TAs include plus (+)- and minus (-)-gossypol, hemigossypolone, and heliocides. To examine foliar TAs' response to physical wounding, the four TA derivatives of a fully glanded G. hirsutum variety JACO GL were quantified by ultra-high performance liquid chromatography. The results show that foliar heliocides increased by 1.7-fold in younger leaves after wounding. While the hemigossypolone level was not affected by the physical wounding, the level of heliocides was significantly increased up to 1.8-fold in the younger leaves. Upland cotton accumulates concentrated carbohydrates, amino acids, and fatty acids in foliar extrafloral nectar (EFN) to serve as a nutrient resource, which attracts both beneficial insects and damaging pests. To better understand the nectar physiology, particularly to determine the temporal dynamics of EFN metabolites in response to the wounding, a gas chromatograph-mass spectrometer (GC-MS) was used to perform metabolic profiling analyses of a G. hirsutum variety Deltapine 383 that has fully developed extrafloral nectaries. A total of 301 compounds were monitored, specifically 75 primary metabolites, two secondary metabolites and 224 unidentified compounds. The physical wounding treatment changed the EFN composition and lowered overall production. The accumulation of 30 metabolites was altered in response to the wounding treatment and threonic acid levels increased consistently. GC-MS combined with Kovat's analysis enabled identification of EFN secondary metabolites including furfuryl alcohol and 5-hyrdomethoxyfurfural, which both have antioxidant and antimicrobial properties that may protect the nectar against microbial pathogens. This study provides new insights into the wounding response of cotton plants in terms of cotton metabolites found in leaf glands and extrafloral nectar as well as highlighting some protective functions of secondary metabolites produced in foliar glands and extrafloral nectaries.
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Affiliation(s)
- Sang‐Hyuck Park
- Department of BiologyColorado State University‐PuebloPuebloColorado
| | - Jodi Scheffler
- Agricultural Research ServiceCrop Genetics Research UnitUSDAStonevilleMississippi
| | - Brian Scheffler
- Agricultural Research ServiceGenomics and Bioinformatics Research UnitUSDAStonevilleMississippi
| | - Charles L. Cantrell
- Agricultural Research ServiceNatural Products Utilization Research UnitUSDA, UniversityMississippi
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10
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Płachno BJ, Stpiczyńska M, Adamec L, Miranda VFO, Świątek P. Nectar trichome structure of aquatic bladderworts from the section Utricularia (Lentibulariaceae) with observation of flower visitors and pollinators. PROTOPLASMA 2018; 255:1053-1064. [PMID: 29404696 PMCID: PMC5994208 DOI: 10.1007/s00709-018-1216-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 01/26/2018] [Indexed: 05/09/2023]
Abstract
In Utricularia, the flower spur is a nectary and in this organ, nectar is produced and stored. This study aimed to examine the structure of the nectary trichomes in four Utricularia species (Utricularia vulgaris L., U. australis R.Br., U. bremii Heer and U. foliosa L.) from the generic section Utricularia. We have investigated whether species with different spur morphology had similar spur anatomy and nectary trichome structure. In Utricularia flowers, nectar is produced by spur capitate trichomes (sessile or stalked). Our results showed that regardless of the various spur morphology, trichomes have similar architecture and ultrastructure. Head cells of these trichomes are transfer cells with an eccrine nectar secretion. Examined species differed in the micromorphology of papillae in spurs. The fly Eristalis tenax was found to be a pollinator of U. vulgaris. Small Halictidae bees seem to be pollinators of U. foliosa.
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Affiliation(s)
- Bartosz J Płachno
- Department of Plant Cytology and Embryology, Jagiellonian University in Kraków, 9 Gronostajowa St, 30-387, Cracow, Poland.
| | - Małgorzata Stpiczyńska
- Botanic Garden, Faculty of Biology, University of Warsaw, Al. Ujazdowskie 4, 00-478, Warsaw, Poland
| | - Lubomír Adamec
- Section of Plant Ecology, Institute of Botany of the Czech Academy of Sciences, Dukelská 135, -37982, Třeboň, CZ, 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
| | - Piotr Świątek
- Department of Animal Histology and Embryology, University of Silesia in Katowice, 9 Bankowa St, 40-007, Katowice, Poland
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11
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Roy R, Schmitt AJ, Thomas JB, Carter CJ. Review: Nectar biology: From molecules to ecosystems. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2017; 262:148-164. [PMID: 28716410 DOI: 10.1016/j.plantsci.2017.04.012] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 04/17/2017] [Accepted: 04/19/2017] [Indexed: 05/06/2023]
Abstract
Plants attract mutualistic animals by offering a reward of nectar. Specifically, floral nectar (FN) is produced to attract pollinators, whereas extrafloral nectar (EFN) mediates indirect defenses through the attraction of mutualist predatory insects to limit herbivory. Nearly 90% of all plant species, including 75% of domesticated crops, benefit from animal-mediated pollination, which is largely facilitated by FN. Moreover, EFN represents one of the few defense mechanisms for which stable effects on plant health and fitness have been demonstrated in multiple systems, and thus plays a crucial role in the resistance phenotype of plants producing it. In spite of its central role in plant-animal interactions, the molecular events involved in the development of both floral and extrafloral nectaries (the glands that produce nectar), as well as the synthesis and secretion of the nectar itself, have been poorly understood until recently. This review will cover major recent developments in the understanding of (1) nectar chemistry and its role in plant-mutualist interactions, (2) the structure and development of nectaries, (3) nectar production, and (4) its regulation by phytohormones.
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Affiliation(s)
- Rahul Roy
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN 55108, USA
| | - Anthony J Schmitt
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN 55108, USA
| | - Jason B Thomas
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN 55108, USA
| | - Clay J Carter
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN 55108, USA.
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12
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Mack JLK, Davis AR. The relationship between cell division and elongation during development of the nectar-yielding petal spur in Centranthus ruber (Valerianaceae). ANNALS OF BOTANY 2015; 115:641-9. [PMID: 25725007 PMCID: PMC4343294 DOI: 10.1093/aob/mcu261] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
BACKGROUND AND AIMS Floral spurs are hollow, tubular outgrowths that typically conceal nectar. By their involvement in specialized pollinator interactions, spurs have ecological and evolutionary significance, often leading to speciation. Despite their importance and diversity in shape and size among angiosperm taxa, detailed investigations of the mechanism of spur development have been conducted only recently. METHODS Initiation and growth of the nectar-yielding petal spur of Centranthus ruber 'Snowcloud' was investigated throughout seven stages, based on bud size and developmental events. The determination of the frequency of cell division, quantified for the first time in spurs, was conducted by confocal microscopy following 4',6-diamidino-2-phenylindole (DAPI) staining of mitotic figures. Moreover, using scanning electron microscospy of the outer petal spur surface unobstructed by trichomes, morphometry of epidermal cells was determined throughout development in order to understand the ontogeny of this elongate, hollow tube. KEY RESULTS Spur growth from the corolla base initially included diffuse cell divisions identified among epidermal cells as the spur progressed through its early stages. However, cell divisions clearly diminished before a petal spur attained 30 % of its final length of 4·5 mm. Thereafter until anthesis, elongation of individual cells was primarily responsible for the spur's own extension. Consequently, a prolonged period of anisotropy, wherein epidermal cells elongated almost uniformly in all regions along the petal spur's longitudinal axis, contributed principally to the spur's mature length. CONCLUSIONS This research demonstrates that anisotropic growth of epidermal cells - in the same orientation as spur elongation - chiefly explains petal spur extension in C. ruber. Representing the inaugural investigation of the cellular basis for spur ontogeny within the Euasterids II clade, this study complements the patterns in Aquilegia species (order Ranunculales, Eudicots) and Linaria vulgaris (order Lamiales, Euasterids I), thereby suggesting the existence of a common underlying mechanism for petal spur ontogeny in disparate dicot lineages.
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Affiliation(s)
- Jaimie-Lee K Mack
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5E2, Canada
| | - Arthur R Davis
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5E2, Canada
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