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Floral nectary anatomy and ultrastructure in mycoheterotrophic plant, Epipogium aphyllum Sw. (Orchidaceae).

Święczkowska E, Kowalkowska AK - ScientificWorldJournal (2015)

Bottom Line: The floral analysis provides strong evidence to conclude that nectar is secreted on the upper surface of pink-coloured papillate ridges and epidermal (adaxial) cells at different place in spur, especially at the apex.The nectar secretion is not dependent on the colour form of E. aphyllum blooming shoots.The floral biology and ultrastructure differ from mycoheterotrophic plants known up to date.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Taxonomy and Nature Conservation, University of Gdansk, Wita Stwosza 59, 80-308 Gdańsk, Poland.

ABSTRACT
Epipogium aphyllum is a European-Asian obligatory mycoheterotrophic orchid containing no chlorophyll. Flowers are not resupinate with a sack-shape spur and cordate lip, which is divided into two parts: the basal (hypochile) and distal one (epichile). The floral analysis provides strong evidence to conclude that nectar is secreted on the upper surface of pink-coloured papillate ridges and epidermal (adaxial) cells at different place in spur, especially at the apex. The exudation on papillae has been observed through the entire anthesis and it has been stained on polysaccharides, proteins, and lipids. The dense cytoplasm of papillae contains profuse endoplasmic reticulum, plentiful vesicles (bigger ones with tannin-like materials), numerous mitochondria, sometimes dictyosomes, starch grains, and plastids with tubular structures. The large electron-dense bodies in cell walls are structurally the same as tannin-like materials from vesicles that are in contact with plasmalemma. The rupture of thin layer of swelled cuticle is caused by pressure of gathered substances exuded due to granulocrine secretion. The idioblasts with raphides occur mainly in tepals tissue. The dynamic changes of the nectar exudation, released through endocrine secretion, have been noticeable during the anthesis: both on the lip and inside the spur. The nectar secretion is not dependent on the colour form of E. aphyllum blooming shoots. The floral biology and ultrastructure differ from mycoheterotrophic plants known up to date.

No MeSH data available.


Related in: MedlinePlus

Ultrastructure of papillae (TEM). (a) Dense cytoplasm with profuse rough or smooth endoplasmic reticulum, plentiful vesicles (bigger ones with tannin-like materials), numerous mitochondria, and dictyosomes. Notice the vesicles with tannin-like materials in contact with plasmalemma (white arrows) and structurally the same electron-dense bodies (asterisks) in cell wall. The thin layer of swelled cuticle (black arrow). (b) Dense cytoplasm of papillae with spherical mitochondria, plastids with tubular structures, and tannin-like materials. (c) Magnification of (a), vesicle with tannin-like materials in contact with plasmalemma (white arrows), the electron-dense bodies (asterisk) in cell wall, thin layer of cuticle, small vesicles present in cytoplasm and in cell wall. (d) Magnification of (a), the electron-dense body (asterisk) in cell wall. (e, f) In cytoplasm plentiful vesicles are present. (bigger ones with tannin-like materials). Notice the vesicles with tannin-like materials in contact with plasmalemma (white arrows) and structurally the same electron-dense body (black arrow) after building into plasmalemma. The ruptured, thin layer of swelled cuticle caused by pressure of gathered substances. (g) Cell wall structure with visible numerous vesicles and secretion gathered under the cuticle. (h, i) More vacuolated (va: vacuole) cells of outgrowth under the papillae with starchless plastids with tubular structures (c: cuticle, cw: cell wall, d: dictyosomes, ER: profiles of endoplasmic reticulum, m: spherical mitochondria, p: plastids, pl: plasmalemma, se: secretion, t: tannin-like materials, and ve: vesicles).
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fig4: Ultrastructure of papillae (TEM). (a) Dense cytoplasm with profuse rough or smooth endoplasmic reticulum, plentiful vesicles (bigger ones with tannin-like materials), numerous mitochondria, and dictyosomes. Notice the vesicles with tannin-like materials in contact with plasmalemma (white arrows) and structurally the same electron-dense bodies (asterisks) in cell wall. The thin layer of swelled cuticle (black arrow). (b) Dense cytoplasm of papillae with spherical mitochondria, plastids with tubular structures, and tannin-like materials. (c) Magnification of (a), vesicle with tannin-like materials in contact with plasmalemma (white arrows), the electron-dense bodies (asterisk) in cell wall, thin layer of cuticle, small vesicles present in cytoplasm and in cell wall. (d) Magnification of (a), the electron-dense body (asterisk) in cell wall. (e, f) In cytoplasm plentiful vesicles are present. (bigger ones with tannin-like materials). Notice the vesicles with tannin-like materials in contact with plasmalemma (white arrows) and structurally the same electron-dense body (black arrow) after building into plasmalemma. The ruptured, thin layer of swelled cuticle caused by pressure of gathered substances. (g) Cell wall structure with visible numerous vesicles and secretion gathered under the cuticle. (h, i) More vacuolated (va: vacuole) cells of outgrowth under the papillae with starchless plastids with tubular structures (c: cuticle, cw: cell wall, d: dictyosomes, ER: profiles of endoplasmic reticulum, m: spherical mitochondria, p: plastids, pl: plasmalemma, se: secretion, t: tannin-like materials, and ve: vesicles).

Mentions: On the cross-section of a lip, the cells of furrow were often collapsed (Figures 2(b), 3(a), and 3(c)) and intensively stained in water-insoluble polysaccharides (Figures 3(a) and 3(c)) and proteins (not illustrated). The 3–5 vascular bundles were noted in parenchyma under the furrow and under the outgrowths with papillate ridges (Figure 3(a)). The tiny starch grains were noted in all lip cells, especially close to the vascular bundles of outgrowths forming ridges with papillae (Figures 3(a) and 3(b)). The presence of starch was various in flowers, without regularity. At the end of anthesis, the starch grains were visible only in outer (abaxial) lip epidermis (Figure 3(d)). The exudation on papillae (Figure 3(e)) was noted through the whole anthesis and was stained on proteins (Figure 3(f)) and lipids (not illustrated). During the secretion process, the enlarged cell nuclei were observed. The staining with Auramina O revealed that the cuticle was very thin (Figure 3(g)). The tissue of other tepals was homogeneous (Figure 3(h)) and was stained on proteins (Figure 3(i)) with tiny starch grains (Figure 3(j)) and with no secretion on their surface. TEM studies of papillae displayed features of secretory activity. The dense cytoplasm contained profuse profiles of rough or smooth endoplasmic reticulum (ER), plentiful vesicles (bigger ones with tannin-like materials), and numerous spherical mitochondria, sometimes dictyosomes and starchless plastids with tubular structures (Figures 4(a), 4(b), 4(e), and 4(f)). The vesicles with tannin-like materials were in contact with plasmalemma (Figures 4(a), 4(c), 4(e), and 4(f)). The electron-dense bodies visible in cell wall structurally resembled the tannin-like material. Moreover, the small vesicles were visible close to irregular plasmalemma and in the cell wall structure (Figures 4(c), 4(e), and 4(f)). The secretion was gathered underneath the thin cuticle (Figures 4(a), 4(e), 4(f), and 4(g)) and caused its rupture (Figures 4(e) and 4(f)). The cells of the outgrowth under the papillae were more vacuolated than papillate cells (Figures 4(g) and 4(h)). Like in papillae (Figure 4(b)), the starchless plastids with tubular structures were visible also in these cells (Figure 4(h)).


Floral nectary anatomy and ultrastructure in mycoheterotrophic plant, Epipogium aphyllum Sw. (Orchidaceae).

Święczkowska E, Kowalkowska AK - ScientificWorldJournal (2015)

Ultrastructure of papillae (TEM). (a) Dense cytoplasm with profuse rough or smooth endoplasmic reticulum, plentiful vesicles (bigger ones with tannin-like materials), numerous mitochondria, and dictyosomes. Notice the vesicles with tannin-like materials in contact with plasmalemma (white arrows) and structurally the same electron-dense bodies (asterisks) in cell wall. The thin layer of swelled cuticle (black arrow). (b) Dense cytoplasm of papillae with spherical mitochondria, plastids with tubular structures, and tannin-like materials. (c) Magnification of (a), vesicle with tannin-like materials in contact with plasmalemma (white arrows), the electron-dense bodies (asterisk) in cell wall, thin layer of cuticle, small vesicles present in cytoplasm and in cell wall. (d) Magnification of (a), the electron-dense body (asterisk) in cell wall. (e, f) In cytoplasm plentiful vesicles are present. (bigger ones with tannin-like materials). Notice the vesicles with tannin-like materials in contact with plasmalemma (white arrows) and structurally the same electron-dense body (black arrow) after building into plasmalemma. The ruptured, thin layer of swelled cuticle caused by pressure of gathered substances. (g) Cell wall structure with visible numerous vesicles and secretion gathered under the cuticle. (h, i) More vacuolated (va: vacuole) cells of outgrowth under the papillae with starchless plastids with tubular structures (c: cuticle, cw: cell wall, d: dictyosomes, ER: profiles of endoplasmic reticulum, m: spherical mitochondria, p: plastids, pl: plasmalemma, se: secretion, t: tannin-like materials, and ve: vesicles).
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig4: Ultrastructure of papillae (TEM). (a) Dense cytoplasm with profuse rough or smooth endoplasmic reticulum, plentiful vesicles (bigger ones with tannin-like materials), numerous mitochondria, and dictyosomes. Notice the vesicles with tannin-like materials in contact with plasmalemma (white arrows) and structurally the same electron-dense bodies (asterisks) in cell wall. The thin layer of swelled cuticle (black arrow). (b) Dense cytoplasm of papillae with spherical mitochondria, plastids with tubular structures, and tannin-like materials. (c) Magnification of (a), vesicle with tannin-like materials in contact with plasmalemma (white arrows), the electron-dense bodies (asterisk) in cell wall, thin layer of cuticle, small vesicles present in cytoplasm and in cell wall. (d) Magnification of (a), the electron-dense body (asterisk) in cell wall. (e, f) In cytoplasm plentiful vesicles are present. (bigger ones with tannin-like materials). Notice the vesicles with tannin-like materials in contact with plasmalemma (white arrows) and structurally the same electron-dense body (black arrow) after building into plasmalemma. The ruptured, thin layer of swelled cuticle caused by pressure of gathered substances. (g) Cell wall structure with visible numerous vesicles and secretion gathered under the cuticle. (h, i) More vacuolated (va: vacuole) cells of outgrowth under the papillae with starchless plastids with tubular structures (c: cuticle, cw: cell wall, d: dictyosomes, ER: profiles of endoplasmic reticulum, m: spherical mitochondria, p: plastids, pl: plasmalemma, se: secretion, t: tannin-like materials, and ve: vesicles).
Mentions: On the cross-section of a lip, the cells of furrow were often collapsed (Figures 2(b), 3(a), and 3(c)) and intensively stained in water-insoluble polysaccharides (Figures 3(a) and 3(c)) and proteins (not illustrated). The 3–5 vascular bundles were noted in parenchyma under the furrow and under the outgrowths with papillate ridges (Figure 3(a)). The tiny starch grains were noted in all lip cells, especially close to the vascular bundles of outgrowths forming ridges with papillae (Figures 3(a) and 3(b)). The presence of starch was various in flowers, without regularity. At the end of anthesis, the starch grains were visible only in outer (abaxial) lip epidermis (Figure 3(d)). The exudation on papillae (Figure 3(e)) was noted through the whole anthesis and was stained on proteins (Figure 3(f)) and lipids (not illustrated). During the secretion process, the enlarged cell nuclei were observed. The staining with Auramina O revealed that the cuticle was very thin (Figure 3(g)). The tissue of other tepals was homogeneous (Figure 3(h)) and was stained on proteins (Figure 3(i)) with tiny starch grains (Figure 3(j)) and with no secretion on their surface. TEM studies of papillae displayed features of secretory activity. The dense cytoplasm contained profuse profiles of rough or smooth endoplasmic reticulum (ER), plentiful vesicles (bigger ones with tannin-like materials), and numerous spherical mitochondria, sometimes dictyosomes and starchless plastids with tubular structures (Figures 4(a), 4(b), 4(e), and 4(f)). The vesicles with tannin-like materials were in contact with plasmalemma (Figures 4(a), 4(c), 4(e), and 4(f)). The electron-dense bodies visible in cell wall structurally resembled the tannin-like material. Moreover, the small vesicles were visible close to irregular plasmalemma and in the cell wall structure (Figures 4(c), 4(e), and 4(f)). The secretion was gathered underneath the thin cuticle (Figures 4(a), 4(e), 4(f), and 4(g)) and caused its rupture (Figures 4(e) and 4(f)). The cells of the outgrowth under the papillae were more vacuolated than papillate cells (Figures 4(g) and 4(h)). Like in papillae (Figure 4(b)), the starchless plastids with tubular structures were visible also in these cells (Figure 4(h)).

Bottom Line: The floral analysis provides strong evidence to conclude that nectar is secreted on the upper surface of pink-coloured papillate ridges and epidermal (adaxial) cells at different place in spur, especially at the apex.The nectar secretion is not dependent on the colour form of E. aphyllum blooming shoots.The floral biology and ultrastructure differ from mycoheterotrophic plants known up to date.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Taxonomy and Nature Conservation, University of Gdansk, Wita Stwosza 59, 80-308 Gdańsk, Poland.

ABSTRACT
Epipogium aphyllum is a European-Asian obligatory mycoheterotrophic orchid containing no chlorophyll. Flowers are not resupinate with a sack-shape spur and cordate lip, which is divided into two parts: the basal (hypochile) and distal one (epichile). The floral analysis provides strong evidence to conclude that nectar is secreted on the upper surface of pink-coloured papillate ridges and epidermal (adaxial) cells at different place in spur, especially at the apex. The exudation on papillae has been observed through the entire anthesis and it has been stained on polysaccharides, proteins, and lipids. The dense cytoplasm of papillae contains profuse endoplasmic reticulum, plentiful vesicles (bigger ones with tannin-like materials), numerous mitochondria, sometimes dictyosomes, starch grains, and plastids with tubular structures. The large electron-dense bodies in cell walls are structurally the same as tannin-like materials from vesicles that are in contact with plasmalemma. The rupture of thin layer of swelled cuticle is caused by pressure of gathered substances exuded due to granulocrine secretion. The idioblasts with raphides occur mainly in tepals tissue. The dynamic changes of the nectar exudation, released through endocrine secretion, have been noticeable during the anthesis: both on the lip and inside the spur. The nectar secretion is not dependent on the colour form of E. aphyllum blooming shoots. The floral biology and ultrastructure differ from mycoheterotrophic plants known up to date.

No MeSH data available.


Related in: MedlinePlus