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Comparative floral spur anatomy and nectar secretion in four representatives of Ranunculaceae.

Antoń S, Kamińska M - Protoplasma (2015)

Bottom Line: Nectar in C. regalis and D. elatum is exuded through micro-channels in the cuticle, whereas in A. lycoctonum and A. vulgaris, it is released by means of cell wall disruption, indicating that the method of nectar secretion here is holocrine.It is proposed that in A. lycoctonum and A. vulgaris, disruption of the cell wall and the release of the entire cell contents into the spur cavity contribute to the composition of the nectar that the latter contains, enriching it with cytoplasmic components.We conclude that the manner of nectar exudation may vary considerably between closely related plant species, regardless of their geographical origin and phylogeny.

View Article: PubMed Central - PubMed

Affiliation: Department of Botany, University of Life Sciences in Lublin, Akademicka 15, 20-950, Lublin, Poland. seba1215@poczta.onet.pl.

ABSTRACT
Nectaries are common in Ranunculaceae. These secretory structures, however, have not been studied in detail despite their importance in plant-animal interactions, and data relating to the structure of nectary spurs, which are so characteristic of several genera of this family, remain scarce. In order to redress this imbalance, we sought, in the present paper, to analyze the anatomical and ultrastructural organization of the nectary spurs of four representatives of Ranunculaceae, i.e., Aconitum lycoctonum L., Aquilegia vulgaris L., Consolida regalis Gray, and Delphinium elatum L. Nectary spurs were examined using light, fluorescence, scanning electron, and transmission electron microscopy. The floral nectaries of A. lycoctonum and A. vulgaris are situated at the apices of the spurs, whereas in C. regalis and D. elatum, the nectary is located along the floor surface of the spurs. Nectar in C. regalis and D. elatum is exuded through micro-channels in the cuticle, whereas in A. lycoctonum and A. vulgaris, it is released by means of cell wall disruption, indicating that the method of nectar secretion here is holocrine. Structurally, the nectary of all four investigated species is quite similar, and its cells are typical of nectar-producing cells described in the literature. It is proposed that in A. lycoctonum and A. vulgaris, disruption of the cell wall and the release of the entire cell contents into the spur cavity contribute to the composition of the nectar that the latter contains, enriching it with cytoplasmic components. We conclude that the manner of nectar exudation may vary considerably between closely related plant species, regardless of their geographical origin and phylogeny.

No MeSH data available.


Related in: MedlinePlus

Scanning electron micrographs and ultrastructure of nectary spur of Consolida regalis: a–b scanning electron micrographs, c–g transmission electron micrographs. a Glabrous surface of inner epidermis. Scale bar = 100 μm. b Details of internal epidermis with highly striate cuticle and nectar residues (arrows) between rows of adjacent epidermal cells. Scale bar = 20 μm. c Details of outer tangential wall of internal epidermis with thick cuticle layer, containing numerous micro-channels. Scale bar = 2 μm. d Internal epidermal cells containing long profiles of rough endoplasmic reticulum, vesicles, large nuclei, and central vacuole, note the numerous plasmodesmata connecting the epidermal cells (arrows). Scale bar = 2 μm. e Section showing cytoplasm of internal epidermal cell containing mitochondria and numerous small vacuoles, note relatively large intercellular space (is) between these cells and adjoining nectary parenchyma. Scale bar = 2 μm. f Cytoplasm of secretory parenchyma cells, note numerous plasmodesmata connecting adjacent cells (arrows). Scale bar = 2 μm. g Secretory parenchyma with rough ER profiles and plastids containing partly hydrolyzed starch grains, note the formation of electron-translucent profile in plastids (asterisk). Scale bar = 2 μm
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Fig6: Scanning electron micrographs and ultrastructure of nectary spur of Consolida regalis: a–b scanning electron micrographs, c–g transmission electron micrographs. a Glabrous surface of inner epidermis. Scale bar = 100 μm. b Details of internal epidermis with highly striate cuticle and nectar residues (arrows) between rows of adjacent epidermal cells. Scale bar = 20 μm. c Details of outer tangential wall of internal epidermis with thick cuticle layer, containing numerous micro-channels. Scale bar = 2 μm. d Internal epidermal cells containing long profiles of rough endoplasmic reticulum, vesicles, large nuclei, and central vacuole, note the numerous plasmodesmata connecting the epidermal cells (arrows). Scale bar = 2 μm. e Section showing cytoplasm of internal epidermal cell containing mitochondria and numerous small vacuoles, note relatively large intercellular space (is) between these cells and adjoining nectary parenchyma. Scale bar = 2 μm. f Cytoplasm of secretory parenchyma cells, note numerous plasmodesmata connecting adjacent cells (arrows). Scale bar = 2 μm. g Secretory parenchyma with rough ER profiles and plastids containing partly hydrolyzed starch grains, note the formation of electron-translucent profile in plastids (asterisk). Scale bar = 2 μm

Mentions: The flowers of C. regalis are zygomorphic, dark blue to purple, and lack fragrance. The double perianth is composed of five sepals and a single, spurred nectariferous petal. The latter is three-lobed and located within the spur of the dorsal, unpaired sepal (Fig. 5a). The secretory tissue is green and located along the ventral surface of the spur (Fig. 5b). The internal epidermis is glabrous and lacks secreting structures on its surface. The cuticle overlying those epidermal cells is striate and lacks evidence of rupture or pores that would allow the release of nectar (Fig. 6a–b). Nectar residues are present on the surface of the nectariferous tissue, especially in the rows of parallel adjacent epidermal cells (Fig. 6b).Fig. 5


Comparative floral spur anatomy and nectar secretion in four representatives of Ranunculaceae.

Antoń S, Kamińska M - Protoplasma (2015)

Scanning electron micrographs and ultrastructure of nectary spur of Consolida regalis: a–b scanning electron micrographs, c–g transmission electron micrographs. a Glabrous surface of inner epidermis. Scale bar = 100 μm. b Details of internal epidermis with highly striate cuticle and nectar residues (arrows) between rows of adjacent epidermal cells. Scale bar = 20 μm. c Details of outer tangential wall of internal epidermis with thick cuticle layer, containing numerous micro-channels. Scale bar = 2 μm. d Internal epidermal cells containing long profiles of rough endoplasmic reticulum, vesicles, large nuclei, and central vacuole, note the numerous plasmodesmata connecting the epidermal cells (arrows). Scale bar = 2 μm. e Section showing cytoplasm of internal epidermal cell containing mitochondria and numerous small vacuoles, note relatively large intercellular space (is) between these cells and adjoining nectary parenchyma. Scale bar = 2 μm. f Cytoplasm of secretory parenchyma cells, note numerous plasmodesmata connecting adjacent cells (arrows). Scale bar = 2 μm. g Secretory parenchyma with rough ER profiles and plastids containing partly hydrolyzed starch grains, note the formation of electron-translucent profile in plastids (asterisk). Scale bar = 2 μm
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Fig6: Scanning electron micrographs and ultrastructure of nectary spur of Consolida regalis: a–b scanning electron micrographs, c–g transmission electron micrographs. a Glabrous surface of inner epidermis. Scale bar = 100 μm. b Details of internal epidermis with highly striate cuticle and nectar residues (arrows) between rows of adjacent epidermal cells. Scale bar = 20 μm. c Details of outer tangential wall of internal epidermis with thick cuticle layer, containing numerous micro-channels. Scale bar = 2 μm. d Internal epidermal cells containing long profiles of rough endoplasmic reticulum, vesicles, large nuclei, and central vacuole, note the numerous plasmodesmata connecting the epidermal cells (arrows). Scale bar = 2 μm. e Section showing cytoplasm of internal epidermal cell containing mitochondria and numerous small vacuoles, note relatively large intercellular space (is) between these cells and adjoining nectary parenchyma. Scale bar = 2 μm. f Cytoplasm of secretory parenchyma cells, note numerous plasmodesmata connecting adjacent cells (arrows). Scale bar = 2 μm. g Secretory parenchyma with rough ER profiles and plastids containing partly hydrolyzed starch grains, note the formation of electron-translucent profile in plastids (asterisk). Scale bar = 2 μm
Mentions: The flowers of C. regalis are zygomorphic, dark blue to purple, and lack fragrance. The double perianth is composed of five sepals and a single, spurred nectariferous petal. The latter is three-lobed and located within the spur of the dorsal, unpaired sepal (Fig. 5a). The secretory tissue is green and located along the ventral surface of the spur (Fig. 5b). The internal epidermis is glabrous and lacks secreting structures on its surface. The cuticle overlying those epidermal cells is striate and lacks evidence of rupture or pores that would allow the release of nectar (Fig. 6a–b). Nectar residues are present on the surface of the nectariferous tissue, especially in the rows of parallel adjacent epidermal cells (Fig. 6b).Fig. 5

Bottom Line: Nectar in C. regalis and D. elatum is exuded through micro-channels in the cuticle, whereas in A. lycoctonum and A. vulgaris, it is released by means of cell wall disruption, indicating that the method of nectar secretion here is holocrine.It is proposed that in A. lycoctonum and A. vulgaris, disruption of the cell wall and the release of the entire cell contents into the spur cavity contribute to the composition of the nectar that the latter contains, enriching it with cytoplasmic components.We conclude that the manner of nectar exudation may vary considerably between closely related plant species, regardless of their geographical origin and phylogeny.

View Article: PubMed Central - PubMed

Affiliation: Department of Botany, University of Life Sciences in Lublin, Akademicka 15, 20-950, Lublin, Poland. seba1215@poczta.onet.pl.

ABSTRACT
Nectaries are common in Ranunculaceae. These secretory structures, however, have not been studied in detail despite their importance in plant-animal interactions, and data relating to the structure of nectary spurs, which are so characteristic of several genera of this family, remain scarce. In order to redress this imbalance, we sought, in the present paper, to analyze the anatomical and ultrastructural organization of the nectary spurs of four representatives of Ranunculaceae, i.e., Aconitum lycoctonum L., Aquilegia vulgaris L., Consolida regalis Gray, and Delphinium elatum L. Nectary spurs were examined using light, fluorescence, scanning electron, and transmission electron microscopy. The floral nectaries of A. lycoctonum and A. vulgaris are situated at the apices of the spurs, whereas in C. regalis and D. elatum, the nectary is located along the floor surface of the spurs. Nectar in C. regalis and D. elatum is exuded through micro-channels in the cuticle, whereas in A. lycoctonum and A. vulgaris, it is released by means of cell wall disruption, indicating that the method of nectar secretion here is holocrine. Structurally, the nectary of all four investigated species is quite similar, and its cells are typical of nectar-producing cells described in the literature. It is proposed that in A. lycoctonum and A. vulgaris, disruption of the cell wall and the release of the entire cell contents into the spur cavity contribute to the composition of the nectar that the latter contains, enriching it with cytoplasmic components. We conclude that the manner of nectar exudation may vary considerably between closely related plant species, regardless of their geographical origin and phylogeny.

No MeSH data available.


Related in: MedlinePlus