How does the nectar of stomata-free nectaries cross the cuticle?

Paiva, Élder Antônio Sousa

doi:10.1590/0102-33062016abb0444

Cited by 40 publications

(23 citation statements)

References 27 publications

(37 reference statements)

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“…The enlargement of the subepithelial cells of the secretory canals disposed on the adaxial side of the spathe reduces the size of the lumen of the canal and causes rupture of subepidermal layers, forming pockets that force the epidermis to rupture, similar to the mechanism of rupture of the subcuticular pockets described by Paiva (2017). Lorio & Hodges (1968) observed that the oil-resin exudation pressure in Pinus taeda reaches 10atm.…”

Section: Discussionmentioning

confidence: 70%

Floral resins of Philodendron adamantinum (Araceae): secretion, release and synchrony with pollinators

2018

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Philodendron is the only genus of Araceae in which resin release occurs in the inflorescence. The resinous secretion adheres to the smooth body surface of the pollinating scarab beetles and allows attachment of pollen grains, making its transport possible. In order to understand the process of resin synthesis and release to the external environment, we used structural, ultrastructural and histochemical analyses at different stages of development of the inflorescences of Philodendron adamantinum. Two types of secretory canals were observed in the spathe: small caliber canals near the abaxial face, and larger caliber canals in the adaxial region. Only the latter canals release secretion into the external environment. The secretory epithelium in these canals is formed by a layer of cuneiform cells, and exhibits secretory activity throughout the development of the spathe. Resin exudation is a peculiar characteristic of these canals and appears to result from pressure exerted by the secretory epithelium and by structural modifications in the wall of cells adjacent to the epidermis, which allow the formation of a separation zone whereby the resin is released. The observed synchrony between anther dehiscence and resin exudation of P. adamantinum enhances the role of this secretion in the pollination process.

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Section: Discussionmentioning

confidence: 70%

Floral resins of Philodendron adamantinum (Araceae): secretion, release and synchrony with pollinators

2018

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“…Although such a model largely presupposes that the cell wall is responsible for restricting secretion reflux, the present study suggests that the radial “strands” of lipophilic material in the nectariferous tissue may also play a role—see further on. Paiva (2017) mentions that in stomata-free nectaries, cuticular pores (hydrophilic pathways) and cuticle rupture or detachment provide the main means by which nectar can be exuded. Although the tests with Sudan III in the present study were carried out on chemically fixed material which may have affected the results, the cuticle stained the same as the “strands” of material traversing the EFN.…”

Section: Discussionmentioning

confidence: 99%

Foliar secretory structures in Ekebergia capensis (Meliaceae)

Tilney

Nel

Wyk

2018

Heliyon

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Ekebergia capensis is a medium-sized to large evergreen to deciduous tree ranging from southern Africa to Ethiopia. Two morphologically-distinct variants of E. capensis, southern and northern, may be recognized in southern Africa. Despite its wide distribution range there appear to be no published reports on the secretory structures occurring on the leaves. In very young leaves, colleters on the petiolules, adjacent portions of the rachis and the midrib of the adaxial leaflet surfaces, secrete fluid which at least partly covers these developing areas. This is the first record of colleters in Meliaceae. In addition, several extrafloral nectaries (EFNs) are found in variable positions on the abaxial side of the leaflets. No stomata are associated with the EFNs. The glandular tissue of active EFNs is surrounded by druse crystals of calcium oxalate and consists of secretory cells some of whose walls are separated by “strands” of amorphous lipophilic material, especially in a radial orientation. EFNs on developing leaves are inconspicuous but with time, frequently become more easily visible due to the accumulation of pinkish/reddish anthocyanins. Even on senescent leaves, shed in autumn, large droplets of nectar are frequently visible on the EFNs. The secretory tissue originates from protoderm and ground tissues. Slight differences in abundance, size, shape, position and structure exist between the EFNs of the southern and northern forms. Varying proportions of glucose, fructose and sucrose were detected in the rather viscous nectar with the most abundant sugar usually being fructose. Ants were only rarely observed feeding on the nectar. This finding is in conflict with the generally accepted idea that EFNs provide food for ants which in turn protect the plant from herbivores. More detailed studies of the chemistry of the nectar, which is relatively copious, may provide clues as to the function.

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“…In the cuticular layer of head cells in the examined Pinguicula, there were polysaccharide micro-canals, which are hydrophilic pathways that most probably form pathways for the release of secretions (Paiva 2016(Paiva , 2017. Such a structure has been described in the cells of various nectary types in many species (e.g.…”

Section: Discussionmentioning

confidence: 96%

Flower nectar trichome structure of carnivorous plants from the genus butterworts Pinguicula L. (Lentibulariaceae)

et al. 2019

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Pinguicula (Lentibulariaceae) is a genus comprising around 96 species of herbaceous, carnivorous plants, which are extremely diverse in flower size, colour and spur length and structure as well as pollination strategy. In Pinguicula, nectar is formed in the flower spur; however, there is a gap in the knowledge about the nectary trichome structure in this genus. Our aim was to compare the nectary trichome structure of various Pinguicula species in order to determine whether there are any differences among the species in this genus. The taxa that were sampled were Pinguicula moctezumae, P. moranensis, P. rectifolia, P. emarginata and P. esseriana. We used light microscopy, histochemistry, scanning and transmission electron microscopy to address those aims. We show a conservative nectary trichome structure and spur anatomy in various Mexican Pinguicula species. The gross structural similarities between the examined species were the spur anatomy, the occurrence of papillae, the architecture of the nectary trichomes and the ultrastructure characters of the trichome cells. However, there were some differences in the spur length, the size of spur trichomes, the occurrence of starch grains in the spur parenchyma and the occurrence of cell wall ingrowths in the terminal cells of the nectary trichomes. Similar nectary capitate trichomes, as are described here, were recorded in the spurs of species from other Lentibulariaceae genera. There are many ultrastructural similarities between the cells of nectary trichomes in Pinguicula and Utricularia.

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How does the nectar of stomata-free nectaries cross the cuticle?

Cited by 40 publications

References 27 publications

Floral resins of Philodendron adamantinum (Araceae): secretion, release and synchrony with pollinators

Floral resins of Philodendron adamantinum (Araceae): secretion, release and synchrony with pollinators

Foliar secretory structures in Ekebergia capensis (Meliaceae)

Flower nectar trichome structure of carnivorous plants from the genus butterworts Pinguicula L. (Lentibulariaceae)

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