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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

Lip spur: (a) adaxial (inner) surface of spur with places of secretion (yellow) at the apex of the spur, the 6th day of anthesis (SEM). (b) Places of secretion inside spur, 4th day (SEM). (c) Secretion on the adaxial surface of spur, 2nd day (TBO). (d) Secretion on the adaxial surface of spur stained for proteins; notice large nuclei, 2nd day (ABB). (e) Secretion inside spur stained for polysaccharides insoluble in water, starch grains visible in cells, 5th day (PAS). (f) Secretion on the adaxial surface of spur, stained for lipids (SBB). (g-h) Secretion on the adaxial surface of spur (TEM) (cw: cell wall; se: secretion).
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fig6: Lip spur: (a) adaxial (inner) surface of spur with places of secretion (yellow) at the apex of the spur, the 6th day of anthesis (SEM). (b) Places of secretion inside spur, 4th day (SEM). (c) Secretion on the adaxial surface of spur, 2nd day (TBO). (d) Secretion on the adaxial surface of spur stained for proteins; notice large nuclei, 2nd day (ABB). (e) Secretion inside spur stained for polysaccharides insoluble in water, starch grains visible in cells, 5th day (PAS). (f) Secretion on the adaxial surface of spur, stained for lipids (SBB). (g-h) Secretion on the adaxial surface of spur (TEM) (cw: cell wall; se: secretion).

Mentions: The SEM results and the cross-sections of spur from different days revealed that the exudation was irregularly present in few places along its whole length (Figures 5(a), 5(b), 6(a), and 6(b)). The secretion was noted on some cells of adaxial (inner) epidermis along the entire length of spur (Figures 5(c), 5(d), 5(e), 5(f), and 5(g)), but in a larger amount at the apex of spur (Figures 5(c) and 5(d)). Though the spur was in the upper position, the nectar was not dripping down. The exudation (Figure 6(c)) was stained on proteins (Figure 6(d)) and slightly on water-insoluble polysaccharides (Figure 6(e), compared with labellar papillae Figures 3(b), 3(e), and 3(f)). The enlarged nuclei were visible in secretory cells (Figures 5(e) and 6(d)), whereas the nuclei were significantly smaller after cessation of secretion.


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

Święczkowska E, Kowalkowska AK - ScientificWorldJournal (2015)

Lip spur: (a) adaxial (inner) surface of spur with places of secretion (yellow) at the apex of the spur, the 6th day of anthesis (SEM). (b) Places of secretion inside spur, 4th day (SEM). (c) Secretion on the adaxial surface of spur, 2nd day (TBO). (d) Secretion on the adaxial surface of spur stained for proteins; notice large nuclei, 2nd day (ABB). (e) Secretion inside spur stained for polysaccharides insoluble in water, starch grains visible in cells, 5th day (PAS). (f) Secretion on the adaxial surface of spur, stained for lipids (SBB). (g-h) Secretion on the adaxial surface of spur (TEM) (cw: cell wall; se: secretion).
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig6: Lip spur: (a) adaxial (inner) surface of spur with places of secretion (yellow) at the apex of the spur, the 6th day of anthesis (SEM). (b) Places of secretion inside spur, 4th day (SEM). (c) Secretion on the adaxial surface of spur, 2nd day (TBO). (d) Secretion on the adaxial surface of spur stained for proteins; notice large nuclei, 2nd day (ABB). (e) Secretion inside spur stained for polysaccharides insoluble in water, starch grains visible in cells, 5th day (PAS). (f) Secretion on the adaxial surface of spur, stained for lipids (SBB). (g-h) Secretion on the adaxial surface of spur (TEM) (cw: cell wall; se: secretion).
Mentions: The SEM results and the cross-sections of spur from different days revealed that the exudation was irregularly present in few places along its whole length (Figures 5(a), 5(b), 6(a), and 6(b)). The secretion was noted on some cells of adaxial (inner) epidermis along the entire length of spur (Figures 5(c), 5(d), 5(e), 5(f), and 5(g)), but in a larger amount at the apex of spur (Figures 5(c) and 5(d)). Though the spur was in the upper position, the nectar was not dripping down. The exudation (Figure 6(c)) was stained on proteins (Figure 6(d)) and slightly on water-insoluble polysaccharides (Figure 6(e), compared with labellar papillae Figures 3(b), 3(e), and 3(f)). The enlarged nuclei were visible in secretory cells (Figures 5(e) and 6(d)), whereas the nuclei were significantly smaller after cessation of secretion.

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