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  • 1
    Electronic Resource
    Electronic Resource
    Evidence for two pathways of phloem loading (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 90 (1994), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The minor veins of small leaf discs, punched out of mature leaves and incubated in 14C-sucrose solution, appear labeled in macro- and microautoradiographs. Discs with a labeled vein pattern and with labeled sieve tubes in microautoradiographs were found in Beta vulgaris, Vicia faba, Gomphrena globosa and Antirrhinum majus. However, in several other plant species, minor veins appeared unlabeled in macroautoradiographs when the discs were incubated in 14C-sucrose. Mesophyll cells (Acer pseudoplatanus, Juglans regia, Fagia, sylvatica, Syringa vulgaris, Laburnum anagyroides), bundle-sheath cells of major veins (Salix viminalis, Robinia pseudoacacia, Commelina communis) or epidermal layers (Ginkgo biloba, Chlorophytum comosum) appeared labeled. Lack of radioactivity in sieve tubes of this latter group was confirmed by microauto-radiography. Using 14C-glucose instead of 14C-sucrose, leaf discs of Beta vulgaris showed no labeled vein pattern and in microautoradiographs the sieve tubes appeared unlabeled. In view of the by-pass phloem loading, this study provides evidence for two pathways of phloem loading.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1994.tb02526.x
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  • 2
    Electronic Resource
    Electronic Resource
    Changes of adenine nucleotide and orthophosphate concentrations in buds of deciduous trees during spring reactivation (1986)
    Springer
    Trees 1 (1986), S. 42-46 
    Details
    ISSN: 1432-2285
    Keywords: Acer ; Adenine nucleotides ; Alnus ; Buds ; Deciduous trees ; Fagus ; Fraxinus ; Orthophosphate ; Quercus ; Reactivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Concentrations of AMP, ADP, ATP, and inorganic phosphate (Pi) were determined in buds of five deciduous tree species (Acer pseudoplatanus, Alnus glutinosa, Fagus sylvatica, Fraxinus excelsior, Quercus robur) during spring reactivation from February to the middle of May. In closed buds of diffuse-porous wood trees (Acer, Alnus, Fagus), the content of adenine nucleotides (AdN) increased temporarily between the middle of February and the middle of March. The main increase of AdN concentration appeared either when buds became swollen (Fraxinus, Fagus, Quercus), or at the time of bud-break (Acer, Alnus). Pi content in general decreased during the course of reactivation. It was almost zero in buds of Quercus at bud-break and afterwards, but in Fraxinus Pi concentration rose when bud-break took place. The extremely low AdN content in Quercus buds is contrasted by a steep increase in AdN content in Fraxinus following bud-break. The decrease of AdN content in emerging leaves of Quercus and Fagus could be related to the high age of these trees.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197023
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  • 3
    Electronic Resource
    Electronic Resource
    Displacement of frequently occurring heacy metals in autumn leaves of beech (Fagus sylvatica) (1987)
    Springer
    Trees 1 (1987), S. 164-171 
    Details
    ISSN: 1432-2285
    Keywords: Deciduous trees ; Fagus sylvatica ; Autumn leaves ; Iron ; Lead ; Manganese ; Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary By utilizing energy-dispersive X-ray microanalysis the heavy metals manganese, iron, zinc and lead were determined in different tissues of beech (Fagus sylvatica L.) autumn leaves. It was observed that all four metals were accumulated in sieve element-companion cell complexes of the leaf veins in the period from the green (2 October) to the brown (23 October) leaf coloration. Concomitantly, the concentration of these metals decreased in certain tissues of the stems subtending the leaves. The major reservoirs of heavy metals in the stems were periderm, cortex, pith and xylem rays. Since sieve element-companion cell complexes of the stems showed increasing metal concentrations during the transition from the green to the brown leaf stage, and since this temporary increase also occurred in the petiole phloem, it is inferred that symplastic transport can be used in addition to apoplastic transport for the displacement of heavy metals. It is assumed that the accumulation of heavy metals in the veins of autumn leaves indicates the deposition of surplus ions which are excluded when leaves are cast off.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193559
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  • 4
    Electronic Resource
    Electronic Resource
    Transport processes in stimulated and non-stimulated leaves of Mimosa pudica (1988)
    Springer
    Trees 2 (1988), S. 7-17 
    Details
    ISSN: 1432-2285
    Keywords: Leaf movements ; Mimosa ; Osmotic mechanisms ; Phloem translocation ; Sucrose unloading ; Turgor release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Mature leaves of Mimosa pudica L. or parts of them were exposed to 14CO2, and translocation was recorded by macroautoradiography. It was observed that considerable amounts of labelled photoassimilates were accumulated in pulvini when the leaf was stimulated. In non-stimulated leaves, no such accumulation of label was observed. Microautoradiographs of pulvinar regions of the non-stimulated leaf showed 14C- label restricted to the phloem. When stimulated, the 14C- label was unloaded from the phloem of the pulvini. Labelled photoassimilates appeared most concentrated in the walls of the collenchymatous cells and beyond in the extensor region of the motor cortex. There, label was accumulated in the apoplastic compartments. Stimulation causes a sudden phloem unloading of sucrose, and its accumulation in the apoplast lowers the water potential which eventually exceeds the osmotic potential of the extensor cells of the motor cortex. By removal of cytoplasmic water the motor cells lose turgidity which results in the closing movement of the leaflets, and — some seconds later — in the bending down of the petiole. In late afternoon night-stimulation triggers sucrose unloading in secondary pulvini. During phases of relaxation, labelled material is taken up by motor cells of the extensor, which concomitantly gain turgor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196974
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  • 5
    Electronic Resource
    Electronic Resource
    Transport processes in stimulated and non-stimulated leaves of Mimosa pudica (1988)
    Springer
    Trees 2 (1988), S. 18-24 
    Details
    ISSN: 1432-2285
    Keywords: Action potential ; Adenine nucleotides ; Aphid stylet ; Mimosa ; Orthophosphate ; Phloem ; Sucrose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Adenosine diphosphate (ADP), adenosine triphosphate (ATP) and orthophosphate were determined in non-stimulated, stimulated and relaxed pulvini of mature Mimosa pudica L. leaves. Additional determinations were made with leaflets, rhachillae, petiole and the stem in the stimulated condition. Results show that the content of adenine nucleotides is approximately twice as high in the pulvini as in the tissues between the pulvini. Orthophosphate, in contrast, occurs at higher concentrations in the connecting tissues than in the pulvini. ATP content is highest in the primary pulvini (0.8 μmol/mg dry wt.) and lowest in the tertiary pulvini. Stimulation causes consumption of ATP with a simultaneous increase in ADP content; however, the response is different in each type of pulvinus. This difference is best expressed in the ATP∶ADP ratio. Stimulation causes the most marked reduction of the ratio (9.5-1.4) in the secondary pulvini which react nyctinastically. Orthophosphate content is reduced by stimulation in all types of pulvini, and is increased during the recovery phase. By using a stylet bundle severed from a feeding aphid by a laser shot as tip for the microelectrode, changes of sieve tube membrane potentials were recorded. The changes of the electropotentials following stimulation show that the sieve tube is the pathway for the transmission of the excitation signal in the form of an action potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196975
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  • 6
    Electronic Resource
    Electronic Resource
    Transport processes in stimulated and non-stimulated leaves ofMimosa pudica (1988)
    Springer
    Trees 2 (1988), S. 7-17 
    Details
    ISSN: 1432-2285
    Keywords: Leaf movements ; Mimosa ; Osmotic mechanisms ; Phloem translocation ; Sucrose unloading ; Turgor release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Mature leaves ofMimosa pudica L. or parts of them were exposed to14CO2, and translocation was recorded by macroautoradiography. It was observed that considerable amounts of labelled photoassimilates were accumulated in pulvini when the leaf was stimulated. In non-stimulated leaves, no such accumulation of label was observed. Microautoradiographs of pulvinar regions of the non-stimulated leaf showed14C- label restricted to the phloem. When stimulated, the14C- label was unloaded from the phloem of the pulvini. Labelled photoassimilates appeared most concentrated in the walls of the collenchymatous cells and beyond in the extensor region of the motor cortex. There, label was accumulated in the apoplastic compartments. Stimulation causes a sudden phloem unloading of sucrose, and its accumulation in the apoplast lowers the water potential which eventually exceeds the osmotic potential of the extensor cells of the motor cortex. By removal of cytoplasmic water the motor cells lose turgidity which results in the closing movement of the leaflets, and — some seconds later — in the bending down of the petiole. In late afternoon night-stimulation triggers sucrose unloading in secondary pulvini. During phases of relaxation, labelled material is taken up by motor cells of the extensor, which concomitantly gain turgor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01196339
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  • 7
    Electronic Resource
    Electronic Resource
    Transport processes in stimulated and non-stimulated leaves ofMimosa pudica (1988)
    Springer
    Trees 2 (1988), S. 18-24 
    Details
    ISSN: 1432-2285
    Keywords: Action potential ; Adenine nucleotides ; Aphid stylet ; Mimosa ; Orthophosphate ; Phloem ; Sucrose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Adenosine diphosphate (ADP), adenosine triphosphate (ATP) and orthophosphate were determined in non-stimulated, stimulated and relaxed pulvini of matureMimosa pudica L. leaves. Additional determinations were made with leaflets, rhachillae, petiole and the stem in the stimulated condition. Results show that the content of adenine nucleotides is approximately twice as high in the pulvini as in the tissues between the pulvini. Orthophosphate, in contrast, occurs at higher concentrations in the connecting tissues than in the pulvini. ATP content is highest in the primary pulvini (0.8 μmol/mg dry wt.) and lowest in the tertiary pulvini. Stimulation causes consumption of ATP with a simultaneous increase in ADP content; however, the response is different in each type of pulvinus. This difference is best expressed in the ATP∶ADP ratio. Stimulation causes the most marked reduction of the ratio (9.5-1.4) in the secondary pulvini which react nyctinastically. Orthophosphate content is reduced by stimulation in all types of pulvini, and is increased during the recovery phase. By using a stylet bundle severed from a feeding aphid by a laser shot as tip for the microelectrode, changes of sieve tube membrane potentials were recorded. The changes of the electropotentials following stimulation show that the sieve tube is the pathway for the transmission of the excitation signal in the form of an action potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01196340
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  • 8
    Electronic Resource
    Electronic Resource
    Transport processes in stimulated and non-stimulated leaves of Mimosa pudica (1988)
    Springer
    Trees 2 (1988), S. 65-72 
    Details
    ISSN: 1432-2285
    Keywords: Calcium ; Chlorine ; Ion shifts ; Mimosa pudica ; Potassium ; Seismonastic movements ; X-ray microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Using energy-dispersive X-ray microanalysis, the concentrations of ions, especially potassium and chlorine, were determined in different tissues of primary and tertiary pulvini of Mimosa pudica. It was shown that stimulating the leaf was followed by ion displacements which were most striking in the outer extensor cells, resulting in turgor loss. Since Ca concentration remains relatively constant in cell walls of collapsed cells, the changes of K concentration are best described by the K:Ca ratio. After stimulation the K:Ca ratio dropped in the outer extensor of the primary pulvinus from 775.3 to 2.37 in the cytoplasm, and from 542.2 to 9.25 in the cell wall. Changes in chlorine content were less striking in the primary pulvinus. The K∶Cl ratios in some cases were lower than 1.0, which indicates that Cl content can increase, while K content is diminished. In the non-stimulated tertiary pulvini the outer extensor cells show high concentrations of Cl, but much lower Cl concentrations were found after stimulation. In contrast to the primary pulvinus the K content of the tertiary pulvini is very low. In the vascular tissues of both primary and tertiary pulvini stimulation is followed by a release of K and Cl out of the sieve element cytoplasm into the apoplast. K then appears accumulated in the cell walls of the collenchymatous tissue. These displacements lead to the assumption that the collenchymatous apoplast temporarily functions as a reservoir for K and to a lesser extent for Cl. With regard to the mechanism of leaf movement after stimulation, the accumulation of ions in the apoplast seems to be initiated by the decrease of water potential triggered by an apoplastic accumulation of unloaded sucrose (Fromm and Eschrich 1988a). The resulting turgor release in the outer extensor is accompanied by an efflux of ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196751
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  • 9
    Electronic Resource
    Electronic Resource
    Mineral partitioning in the phloem during autumn senescence of beech leaves (1988)
    Springer
    Trees 2 (1988), S. 73-83 
    Details
    ISSN: 1432-2285
    Keywords: Autumn leaves ; Fagus sylvatica ; Mineral retrieval ; Phloem transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary During the period of leaf senescence in fall, the minerals Mg, Ca, K, P, Cl, S, and Si were compared for occurrence and density in tissue compartments of leaf blade, petiole, and subtending stem of beech (Fagus sylvatica L.). Measurements were made by energy-dispersive X-ray microanalysis. The plant material was collected on 2,9, 16 and 23 October, and showed green, greenyellow, yellow, and red-brown autumn leaf coloration. Mg, K, and P were retrieved from the leaf blade prior to shedding, and deposited mainly in cortex and pith tissues of the stem. S and Ca remained in the leaf, and Si and Cl appeared to accumulate in the leaf prior to shedding. During the four stages of leaf senescence, the phloem compartments of the petiole showed considerable changes in mineral content. In addition, leaf senescence in several cases was accompanied by ion shifting from symplastic to apoplastic compartments and vice versa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196752
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  • 10
    Electronic Resource
    Electronic Resource
    The induction of sun and shade leaves of the European beech (Fagus sylvatica L.): anatomical studies (1989)
    Springer
    Trees 3 (1989), S. 1-10 
    Details
    ISSN: 1432-2285
    Keywords: Differentiation ; Leaf primordia ; Fagus sylvatica ; Sun shade leaves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Primordia from buds of sun and shade twigs of European beech (Fagus sylvatica L.) were collected six times a year for anatomical investigations. Differentiation into sun-leaf and shade-leaf primordia was first observed in early August. Sun-leaf primordia had five, and shade-leaf primordia four layers of mesophyll meristem cells. With potted graft unions of beeches possible structural changes of leaf primordia were investigated. Trees adapted to shade develop sun-leaf primordia when put into full daylight, provided the transfer happened before July. Trees adapted to full daylight developed leaf primordia which remained structurally sun-leaf primordia when the plant was kept under shade conditions. Shadeleaf branches of young beech trees cut in February in order to expose the shade buds to full daylight developed either shade leaves or intermediate shade/sun leaves. These experiments show that the subtending leaf may provide the developing axillary bud with photoassimilates, but its character, whether sun or shade leaf, has no influence on the character of the developing leaf primordia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00202394
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