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  • 11
    Electronic Resource
    Electronic Resource
    Accumulation of potassium by differentiating metaxylem elements of maize roots (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 69 (1987), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The previous demonstration that the large late metaxylem vessels of field-grown maize (Zea mays L. cv. Rosella) roots do not lose their crosswalls until they are 20–30 cm from the tip, and that the presence of a soil sheath outside the root was indicative of immature vessels within, greatly strengthened the hypothesis that ion accumulation into these roots was by uptake into living xylem element vacuoles. Proposals that salt movement into the xylem was by leakage or secretion into dead vessels became much less plausible. Potassium concentration in the vacuoles of late metaxylem elements was measured by X-ray microanalysis in unetched fracture faces of bulk, frozen-hydrated pieces of sheathed roots, and found to be in the range 150–400 mM. Potassium concentration in open vessels of bare roots, measured both with the microprobe and by spectrophotometry of aspirated sap, was in the range of 5 to 25 mM. It is concluded that uptake of potassium (and possibly other ions) is into living xylem elements, and that its release to the transpiration stream occurs by the breakdown of their crosswalls and the addition of their vacuoles to the solution in the vessels above.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1987.tb01947.x
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  • 12
    Electronic Resource
    Electronic Resource
    Water efflux from the surface of field-grown grass roots. Observations by cryo-scanning electron microscopy (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 95 (1995), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Field-grown roots of maize, oats, barley and crabgrass collected at different times of day and night have been examined by cryo-scanning electron microscopy. Droplets and blobs (their high water content confirmed by X-ray microanalysis) were observed on the young root surfaces and within interstices of the rhizosheaths of guttating plants, particularly in the early morning. Plants collected at midday and in the afternoon had very few or none of these watery deposits. I propose that water released from the root surface during the night allows the expansion of root-cap mucilage into the surrounding soil. When transpiration resumes, the mucilage is dried and binds tightly to the surrounding soil particles, thus stabilizing the coherent rhizosheath. This nocturnal water effflux may also facilitate nutrient uptake into the root when transpiration resumes. The water efflux to the rhizosheaths may be driven by root pressure and thus differs from the passive water loss from the root thought to occur during hydraulic lift.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1995.tb00830.x
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  • 13
    Electronic Resource
    Electronic Resource
    Localisation of translocated 14C in roots and root exudates of field-grown maize (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 65 (1985), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The roots of a mature, field-grown maize plant are dimorphic: the primary root and those from the oldest nodes are bare with a heavily lignified cortex arid sloughed epidermis; those from younger nodes, except for a bare elongation zone, have an intact epidermis surrounded by a persistent soil sheath. Sheathed roots consistently have more layers of cortical cells, but the ratio of volumes of cortex to stele (ca 4) and the cross-sectional area of phloem (ca3× 10−2 mm2) are similar in each type. Assimilated carbon (from 14C applied to a small area of one leaf) was translocated to all roots and actively metabolized in cortex and stele of both types. After 1 to 2 days the proportion of 14C exuded from a given length of mature root into its soil sheath, or into the adjacent unattached soil in the case of bare roots, was the same (5%) in both root types when compared with the ethanol-soluble 14C in the tissues of this length. Up to 75% of the ethanol-soluble label in the roots was in a cationic fraction (amino acids and unidentified compounds), ca 1% was in an anionic fraction and the remainder was in a neutral fraction (sugars). Approximately equal amounts of soluble 14C were found in the stele, cortex and laterals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1985.tb08661.x
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  • 14
    Electronic Resource
    Electronic Resource
    The expansion of maize root-cap mucilage during hydration. 2. Observations on soil-grown roots by cryo-scanning electron microscopy (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 97 (1996), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Expansion of root-cap mucilage during hydration was followed by cryo-scanning analytical microscopy of soil-grown roots of diploperennis and Zea mays. Roots examined directly from the soil have no expanded mucilage. Their condensed, unexpanded mucilage is in three domains, periplasmic, intercellular and peripheral to the cap tissue. Carbon concentration is the same in the three domains. During hydration there is no change in carbon concentration as the condensed mucilage moves through these three domains; however there is a sharp drop at the periphery where a gel phase transition occurs. The rate of expansion of the mucilage blob around the root tip is limited by the rate of this gel phase transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1996.tb00503.x
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  • 15
    Electronic Resource
    Electronic Resource
    Evaluation of the specificity of lectin binding to sections of plant tissue (1985)
    Springer
    Histochemistry and cell biology 83 (1985), S. 265-277 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Hand sections of young corn root tips have been used in a study of problems encountered in the binding of fluorescently-labelled lectins to plant tissue. It was found, surprisingly, that with lectins specific for a sugar known to be present (Lotus andUlex lectins forl-fucose), with a lectin specific for a sugar thought not to be present (wheat-germ agglutinin for N-acetylglucosamine), with non-lectin glycoprotein and protein (γ-globulin and bovine serum albumin) and with basophilic dyes (alcian blue and toluidine blue), a coincidental binding pattern similar to the pattern of autofluorescence in the same tissue was obtained. Corn root tissues include cell walls composed of complex polysaccharides esterified with ferulic acid residues, as well as mucilages which are highly hydrated and expanded. In such material, neither standard inhibition controls with haptens nor the use of a wide range of lectin concentrations are adequate to distinguish clearly specific and non-specific binding of fluorescently-labelled lectin. Therefore, lectins are not the simple test probes they have been supposed. Before interpreting results obtained in using fluorescently-labelled lectins on any tissue sections, all available information (biochemical as well as histochemical) about the tissue must be considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00953995
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  • 16
    Electronic Resource
    Electronic Resource
    Evaluation of colour transparency films for photomicrography of fluorescent structures (1981)
    Springer
    Histochemistry and cell biology 73 (1981), S. 121-129 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ability of 17 commercial colour transparency films to record a range of colours (reds through pale blue) of fluorescent structures in plant tissues is examined. For faint, fleeting fluorescence Ektachrome Professional EPD 200 processed for ASA 400 is best. For more intense and/or stable fluorescence Ektachrome ER 64 processed for ASA 125 is best.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00493138
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  • 17
    Electronic Resource
    Electronic Resource
    The rhizosphere in Zea: new insight into its structure and development (1982)
    Springer
    Planta 156 (1982), S. 45-61 
    Details
    ISSN: 1432-2048
    Keywords: Cells, detached ; Mucilage ; Rhizosphere ; Root, structure and development ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Some of the nodal roots of field-grown Zea mays L. bear a persistent soil sheath along their entire length underground except for a glistening white soil-free zone which extends approximately 25 mm behind the root cap. These roots are generally unbranched. The histology of the surface and the rhizosphere of the sheathed roots has been examined by correlated light and electron microscopy. All mature peripheral tissues including root hairs, are largely intact and apparently alive where enclosed by the soil sheath. The sheath is permeated by extracellular mucilage which is histochemically distinct from the mucilage at the epidermal surface, but similar to that produced by the root cap. Isolated cells resembling those sloughed from the sides of the root cap persist in the soil sheath along the length of these roots. Fresh whole mounts of the sheath show that these detached cells may be alive and streaming vigorously even at some distance from the root cap. Rhizosphere mucilage is associated with the isolated cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393442
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  • 18
    Electronic Resource
    Electronic Resource
    Mild temperature “stress” and callose synthesis (1977)
    Springer
    Planta 136 (1977), S. 65-70 
    Details
    ISSN: 1432-2048
    Keywords: Callose ; Temperature stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seedlings of Zea mays L., Sorghum vulgare, Pisum sativum L., Phaseolus aureus, Glycine max L. and Lycopersicum esculentum were grown at 20°C and at 26°C. The seedlings were fixed in glutaraldehyde and sections were examined for aniline-blue-induced fluorescence, which is supposedly indicative of β-1,3-glucans or callose. There was much more aniline-blue fluorescence in Zea, Glycine and Phaseolus seedlings grown at 20°C compared with 26°C whereas Pisum and Lycopersicum seedlings grown at 26°C showed more fluorescence than those grown at 20°C. In Zea, large deposits of fluorescent material were particularly noticeable in the walls of elongating cells around the shoot apex and in root-cap cells, and appeared to be closely associated with a few of the pitfields. The remaining pitfields showed the normal, low level of aniline-blue fluorescence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387927
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  • 19
    Electronic Resource
    Electronic Resource
    Regeneration of vascular tissue in wounded pea roots (1979)
    Springer
    Planta 145 (1979), S. 167-173 
    Details
    ISSN: 1432-2048
    Keywords: Pisum ; Regeneration ; Root (regeneration) ; Vascular tissue ; Wound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Severance of the stele of young main roots of pea (Pisum sativum L.) results in formation of a bridge of vascular tissue in the remaining cortex. Cell divisions occur close to the severed vascular tissues on both the proximal and distal sides of the cut within 24 h. Differentiation of new vascular strands subsequently begins in the same locations and progresses from both sides of the wound into the remaining cortex and also back along the original vascular strands. Most of the vascular tissue which forms the bridge through the cortex differentiates in the acropetal direction. Continuous strands composed of single sieve elements bypass the wound somewhat sooner than the first complete xylem strands; the latter in 60–70% of the cases, are present by 3 d. Cambial activity subsequently adds more xylem and phloem. Vascular regeneration is not affected by removal of the epicotyl or the root tip; it is greatly reduced but not prevented by removal of the cotyledons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388713
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  • 20
    Electronic Resource
    Electronic Resource
    An investigation of the role of solutes in the xylem sap and in the xylem parenchyma as the source of root pressure (2000)
    Springer
    Protoplasma 211 (2000), S. 183-197 
    Details
    ISSN: 1615-6102
    Keywords: Cell turgor ; Guttation ; Osmotic potentials ; Root pressure ; Xylem sap ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Solute osmotic potentials (Ψx) in the vessels of hydroponically grown maize roots were measured to assess the osmotic-xylem-sap mechanism for generating root pressure (indicated by guttation). Solutes in vessels were measured in situ by X-ray microanalysis of plants frozen intact while guttating. Osmotic potentials outside the roots (Ψo) were changed by adding polyethylene glycol to the nutrient solution. Guttation rate fell when Ψo was decreased, but recovered towards the control value during 3–5 days when Ψo was greater than or equal to −0.3 MPa, but not when Ψo was equal to −0.4 MPa. In roots stressed to Ψo = −0.3 MPa, Ψx, was always more positive than Ψo, and Ψx changed only slightly (ca. 0.05 MPa). Thus the adjustment in the roots which increased root pressure cannot be ascribed to Ψx, contradicting the osmotic-xylem-sap mechanism. An alternative driving force was sought in the osmotic potentials of the vacuoles of the living cells (Ψv), which were analysed by microanalysis and estimated by plasmolysis. Ψv showed larger responses to osmotic stress (0.1 MPa). Some plants were pretreated with abundant KNO3 in the nutrient solution. These plants showed very large adjustments in Ψv (0.4 MPa) but little change in Ψx (0.08 MPa). They guttated by 4 h after Ψo was lowered to −0.4 MPa. It is argued that turgor pressure of the living cells is a likely alternative source of root pressure. Published evidence for high solute concentrations in the xylem sap is critically assessed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01304486
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