Ultrastructural studies on the developing secretory nodules of Hypericum perforatum

Onelli, Elisabetta; Rivetta, Alberto; Giorgi, Annamaria; Bignami, Mauro; Cocucci, M.; Patrignani, G.

doi:10.1078/0367-2530-00019

Cited by 34 publications

(45 citation statements)

References 33 publications

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“…Chloroplasts are known to contain an extremely active acetyl CoA synthetase, and Ohlrogge and Browse (1995) proposed that the synthesis of acetyl CoA in the mitochondria was followed by transport into the chloroplast. However, the absence of chloroplasts and the presence of only a few mitochondria in the dark gland cells (Onelli et al, 2002) make it unlikely that these steps can take place in the dark glands. …”

Section: Discussionmentioning

confidence: 99%

“…The presence of ribosomes may indicate the production of cytoplasmic proteins such as enzymes for active transport of metabolites. Onelli et al (2002) also showed the presence of numerous plasmodesmata in the outer flat cells of dark glands, suggesting an intense symplastic transport of photosynthates into the glandular cells.…”

Section: P H O T O S Y N T H E S Ismentioning

confidence: 99%

“…Moreover, the dark canals located in different organs (Figs 10 and 11), also known to be associated with veins (Curtis and Lersten, 1990), could be a route of transport as proposed by Williams (1954). Multi-vesicular structures in outer flat cells of developed dark glands were investigated by Onelli et al (2002), who showed that the content is similar to the cytoplasm, with ribosome-like structures. The presence of ribosomes may indicate the production of cytoplasmic proteins such as enzymes for active transport of metabolites.…”

Section: P H O T O S Y N T H E S Ismentioning

confidence: 99%

“…However, there is no experimental evidence that Hy-G or their precursors are synthesized or accumulated in dark glands, or that they are transported from dark glands to different organs or vice versa, nor is there any information on the mechanisms of transport. In contrast, extensive research has been conducted on the anatomical and histological characterization of the dark glands on leaves and petals, starting in the 19th Century (Green, 1884, and references therein; Onelli et al, 2002, Maggi et al, 2004. In several studies, dark glands are proposed as the site where biologically active substances accumulate (McKey, 1979;Curtis and Lersten, 1990;Fornasiero et al, 1998), although no direct evidence of chemical analysis has been presented.…”

Section: Introductionmentioning

confidence: 99%

“…Morphologically, H. perforatum plants are characterized by the presence of several types of secretory structures, including translucent glands, dark glands and secretory canals (Curtis and Lersten, 1990;Fornasiero et al, 1998;Bottega et al, 1999). Dark glands, probably first named by Green (1884), are also known as 'nodules' (Curtis and Lersten, 1990) or 'black nodules' (Onelli et al, 2002;Maggi et al, 2004). This gland is the most important secretory structure in H. perforatum plants.…”

Section: Introductionmentioning

confidence: 99%

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Plant–Environment Interactions: Accumulation of Hypericin in Dark Glands of Hypericum perforatum

et al. 2006

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Background and Aims Hypericum perforatum is a perennial herbaceous plant and an extract from this plant has a significant antidepressant effect when administered to humans. The plant is characterized by its secretory glands, also known as dark glands, which are mainly visible on leaves and flowers. The current study evaluates the influence of several environmental factors and developmental stages of the plant on the accumulation and synthesis of hypericin and pseudohypericin (Hy-G), the major bioactive constituents, in H. perforatum plants.Methods The appearance of dark glands on different parts of the plant, under several environmental conditions, was monitored by microscopy. Hy-G concentrations were quantified by high-performance liquid chromatography.Key Results A significant presence of dark glands accompanying the highest concentrations of Hy-G was observed in the stamen tissues more than in any other organ of H. perforatum. A linear relationship between the number of dark glands and net photosynthetic rate of the leaf and Hy-G concentration in the leaf tissue was also established. A very high concentration of Hy-G was measured in the dark-gland tissues, but in the tissues without any dark glands it was almost absent. The presence of emodin, a precursor of Hy-G, at a high concentration in the dark-gland tissues, and its absence in the surrounding tissues was also observed, suggesting that the site of biosynthesis of Hy-G is in the dark-gland cells. A significantly low concentration of Hy-G (occasionally non-detectable) was measured in the xylem sap of the stem tissues. The dark-gland tissues collected from leaves, stems or flowers contained similar concentrations of Hy-G.Conclusions The concentration of Hy-G in various organs of H. perforatum plants is dependent on the number of dark glands, their size or area, not on the location of the dark glands on the plant. The study provides the first experimental evidence that Hy-G is synthesized and accumulates in dark glands.

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Section: Discussionmentioning

confidence: 99%

Section: P H O T O S Y N T H E S Ismentioning

confidence: 99%

Section: P H O T O S Y N T H E S Ismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Plant–Environment Interactions: Accumulation of Hypericin in Dark Glands of Hypericum perforatum

et al. 2006

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Harnessing Fungal Endophytes for Plant and Human Health

Deka

Tayung

Jha

2017

Sustainable Development and Biodiversity

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Hypericaceae

Stevens

2007

Flowering Plants · Eudicots

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Evergreen or sometimes deciduous herbs, shrubs or trees; glands or canals in most parts of the plant; xanthones widespread; hairs uni-or multicellular, eglandular, colleters common; terminal bud scaly or naked; leaves opposite, occasionally whorled or alternate, entire, estipulate; inflorescences terminal, more or less cymose, rarely axillary or flowers single, flowers polysymmetric, perfect, usually with prophylls; sepals free, (2-)4-5; petals (3)4-5, free; stamens (9-)∞, free or variously fasciculate or connate, anthers < 1(-1.2) mm long, dithecate, extrose, opening by slits, connective often with glands, staminodes alternipetalous or 0; nectary absent; ovary superior, 3-5-locular, placentation axile to parietal, ovules 1-∞/carpel, anatropous, bitegmic, tenuinucellate; stylodia free or basally more or less fused or style single, stigmas more or less expanded, smooth and sticky or ± punctate and papillate; fruit baccate or capsular, rarely a drupe; seeds small, winged or not, exotegmen lignified, with sinuous anticlinal walls; embryo straight or rarely curved; endosperm initially nuclear, often absent at maturity; germination epigeal, phanerocotylar.A family with 9 genera and 540 species; ± worldwide.Vegetative Morphology. Hypericaceae are mostly shrubs to trees, but there are some annual herbs (Hypericum). Taxa growing in drier regions (Hypericum, Psorospermum [= Harungana]) tend to develop a lignotuber, from which they sprout after fire or drought; root suckering occurs in Hypericum (Hagemann 1989 and references therein;Hagemann and Meusel 1984) and Vismia. Architectural models within Vismia vary (Vester 1999).

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Ultrastructural studies on the developing secretory nodules of Hypericum perforatum

Cited by 34 publications

References 33 publications

Plant–Environment Interactions: Accumulation of Hypericin in Dark Glands of Hypericum perforatum

Plant–Environment Interactions: Accumulation of Hypericin in Dark Glands of Hypericum perforatum

Harnessing Fungal Endophytes for Plant and Human Health

Hypericaceae

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