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  • 1
    Electronic Resource
    Electronic Resource
    The paraveinal mesophyll of soybean leaves in relation to assimilate transfer and compartmentation (1983)
    Springer
    Planta 157 (1983), S. 422-431 
    Details
    ISSN: 1432-2048
    Keywords: Assimilate compartmentation ; Glycine (paraveinal mesophyll) ; Paraveinal mesophyll ; Vacuolar protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrogen and carbohydrate assimilates were temporally and spatially compartmented among various cell types in soybean (Glycine max L., Merr.) leaves during seed filling. The paraveinal mesophyll (PVM), a unique cell layer found in soybean, was demonstrated to function in the synthesis, compartmentation and remobilization of nitrogen reserves prior to and during the seed-filling stages. At anthesis, the PVM vacuoles contain substantial protein which completely disappears by two weeks into the seed filling. Distinct changes in the PVM cytoplasm, tonoplast and organelles were correlated with the presence or absence of the vacuolar material. Microautoradiography following the accumulation of several radiolabeled sugars and amino acids demonstrated the glycoprotein nature of the vacuolar material. Incorporation of methionine, leucine, glucose, and glucosamine resulted in heavy labelling of the PVM vacuole, in contrast to galactose, proline, and mannose which resulted in a much reduced labelling pattern. In addition, starch is unequally compartmented and degraded among the various leaf cells during seed filling. At the end of the photoperiod at the flowering stage, the highest starch accumulation was in the second palisade layer followed by the spongy mesophyll and the first (uppermost) palisade layer. Starch in the first palisade layer was completely degraded during the dark whereas the starch in the second palisade and spongy mesophyll was not remobilized to any appreciable extent. By mid-podfilling (approximately five weeks postanthesis) starch was absent in the first palisade layer at the end of the photoperiod while the second palisade and spongy mesophyll layers contained substantial starch. Starch was remobilized from these latter cells during the remainder of seed filling when current photosynthetic production is low. Structural changes associated with cell senescence first appear in the upper palisade layer and then progress (excluding the PVM) to the second palisade and spongy mesophyll layer. The PVM and phloem appear to retain their structural integrity into the leaf yellowing stage. Reducing sink capacity by pod removal resulted in a continued accumulation of vacuolar protein, an increase in cytoplasmic volume, and fragmentation of the vacuole in the PVM. Pod removal also resulted in an increased amount of accumulated starch (which did not turn over) in all mesophyll layers, and an increase in cell size and cell-wall thickness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397199
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  • 2
    Electronic Resource
    Electronic Resource
    The paraveinal mesophyll of soybean leaves in relation to assimilate transfer and compartmentation (1983)
    Springer
    Planta 157 (1983), S. 411-421 
    Details
    ISSN: 1432-2048
    Keywords: Assimilate compartmentation ; Dictyosome ; Glycine (paraveinal mesophyll) ; Paraveinal mesophyll ; Translocation (assimilates) ; Vacuolar protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The paraveinal mesophyll (PVM) is a unique and specialized, one-cell-thick tissue spanning the vascular bundles at the level of the phloem in soybean (Glycine max) (L.) Merr.) leaves. Its position within the leaf dictates that all photosynthate produced in the palisade and spongy mesophyll must pass through this specialized layer enroute to the phloem. Symplastic continuity, via plasmodesmata, exists between the PVM and bundle sheath, palisade parenchyma and spongy mesophyll. During leaf ontogeny the PVM is the first tissue to differentiate and at maturity these cells are six to eight times larger than other mesophyll cells, are highly vacuolate, and are interconnected by tubular arms. The PVM undergoes several unique structural and metabolic modifications during leaf development. The PVM cytoplasm, in vegetative plants, is dense, enriched in rough endoplasmic reticulum and dictyosomes, but contains few, small starch-free chloroplasts and few microbodies. Unlike the tonoplast of mesophyll cells, the tonoplast of the PVM is unusually thick and dense-staining. During leaf development the vacuoles of PVM cells accumulate a glycoprotein derived from the dictyosomes which reacts with the protein staining reagents, mercuric bromophenol blue and sulfaflavine, and is degraded by Pronase. Both the vacuolar material and tonoplast are also stained by phosphotungstic acid, which at low pH is relatively selective for glycoprotein. A unique role of the PVM in the transport and compartmentation of nitrogen reserves in soybeans is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397198
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Specialized cellular arrangements in legume leaves in relation to assimilate transport and compartmentation: comparison of the paraveinal mesophyll (1983)
    Springer
    Planta 159 (1983), S. 415-422 
    Details
    ISSN: 1432-2048
    Keywords: Assimilate translocation ; Leguminosae (paraveinal mesophyll) ; Paraveinal mesophyll ; Vacuolar protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Leaves of eight species of Leguminosae-Papilionoideae were examined for the presence of a highly specialized cell layer called the paraveinal mesophyli (PVM). Three species, Glycine max (L.) Merr, Psophocarpus tetragonolobus D.C. and Vigna radiata L., contained PVM; five (Medicago sativa L., Phaseolus vulgaris L., Pisum sativum L., Vicia faba L., Vigna unguiculata L.) did not. The PVM of G. max and P. tetragonolobus was anatomically identical and consisted of large, interconnected, multiarmed cells forming a network, one cell thick, spanning the region between vascular bundles and abutting the bundle sheath at the level of the phloem. The PVM of V. radiata differed in that elaborate extensions of individual bundle-sheath cells comprised the entire intervascular network. The PVM cells of all three species were large, contained a dense, thin peripheral layer of cytoplasm, and a large central vacuole. The cytoplasm contained few small chloroplasts and few microbodies, but was enriched in rough endoplasmic reticulum. Plasmodesmata were common in crosswalls between adjacent PVM cells and between PVM cells and other cell types abutting them. Vacuolar material was present in all three species, but was variable in appearance. That of G. max was present in large amounts, semifibrillar and finely dispersed. That of P. tetragonolobus was also present in large amounts but primarily as large aggregates, although some fibrillar material was also present. Vigna radiata had small amounts of vacuolar material evenly distributed between small aggregates and dispersed fibrils. Removal of flowers or young pods resulted in further increase of the vacuolar material in G. max PVM and increase of the fibrillar material in P. tetragonolobus, but had no appreciable affect on the vacuolar material in V. radiata. Histochemical staining indicated the vacuolar material in G. max and P. tetragonolobus was proteinaceous.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392077
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanism of transport of vegetative storage proteins to the vacuole of the paraveinal mesophyll of soybean leaf (1997)
    Springer
    Protoplasma 200 (1997), S. 174-185 
    Details
    ISSN: 1615-6102
    Keywords: Glycine max ; Golgi ; Paraveinal mesophyll ; Protein targeting ; Vegetative storage protein ; Vesicle trafficking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Microscopy techniques were used to identify the pathway of transport of soybean leaf vegetative storage proteins (VSPα/β and VSP94) to the vacuoles of a specialized cell type, the paraveinal mesophyll (PVM), where they accumulate. PVM cells are enriched in endoplasmic reticulum and Golgi bodies relative to surrounding mesophyll cells. The margins of medial and trans Golgi cisternae had attached or closely associated noncoated vesicles with densely staining membranes and lumenal contents of the same appearance as material that accumulated in the vacuole. These vesicles appeared to be transported preferentially to the tonoplast, where fusion with the membrane released the granular contents into the vacuole. Cytochemical staining with phosphotungstic acid and silver methenamine supported this interpretation as both the Golgi vesicles and the tonoplast stained intensely with these reagents, unlike the tonoplast of mesophyll cells which do not accumulate VSP. Immunocytochemical localization for VSPα/β labeled the Golgi bodies and associated vesicles, and vacuolar material in PVM cells, but not in mesophyll. Similar labeling was seen in PVM of another legume species previously found to accumulate antigenically similar VSPs. Immunolocalization for VSP94, a lipoxygenase, labeled the PVM cytosol and material in the PVM vacuole, but not the Golgi or vesicles. The results of this study demonstrate that the Golgi pathway is utilized for transport of VSPα/β in the PVM, which follows the mechanism of deposition demonstrated for certain seed storage proteins. VSP94 appeared to follow a separate path for accumulation in PVM vacuoles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01283293
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    Paper (German National Licenses)
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