Summary
The tracer Cellufluor has been used to test the apoplastic permeability of the fungal sheath inPisonia grandis R. Br. mycorrhizas. In the tip region in the immediate vicinity of the root cap, where the sheath is not yet fully differentiated, Celluflor penetrates as far as the root epidermal cells. Behind this (i.e. just proximal to it) in differentiated regions, where the ultrastructure of both the root and fungal cells indicates that the mycorrhiza is likely to be functionally active, the sheath is impermeable to Cellufluor. During the development and differentiation of the sheath, the interhyphal spaces become filled with extracellular material. In the outer and middle regions this becomes electron opaque after fixation and staining. It is proposed that the dramatic decrease in apoplastic permeability over a short distance back from the root apex as the fungal sheath differentiates results from secretion of extracellular material by the fungus and its modification by deposition of phenolic substances. The symplastic pathway within the fungus may be very important for radial transfer of materials across the sheath. Blockage of the sheath apoplast could provide a sealed apoplastic compartment at the fungus-root interface, with resulting increase in efficiency of transfer between partners. The implications of these observations are discussed in relation to radial transfer across the sheath and transfer between partners in sheathing mycorrhizas in general.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Alexander C, Jones D, McHardy WJ (1987) Scanning electron microscopy of cryofixed mycorrhizas of sitka spruce,Picea sitchensis (Bong.) Carr.: a comparison with critical point-dried material. New Phytol 105: 613–617
Ashford AE, Allaway WG (1982) A sheathing mycorrhiza onPisonia grandis R. Br. (Nyctaginaceae) with development of transfer cells rather than a Hartig net. New Phytol 90: 511–519
— — (1985) Transfer cells and Hartig net in the root epidermis of the sheathing mycorrhiza ofPisonia grandis R. Br. from Seychelles. New Phytol 100: 595–612
Atkinson MA (1975) The fine structure of mycorrhizas. PhD Thesis, University of Oxford, England
Blasius D, Feil W, Kottke I, Oberwinkler F (1986) Hartig net structure and formation in fully ensheathed ectomycorrhizas. Nord J Bot 6: 837–842
Canny MJ, McCully ME (1986) Locating water-soluble vital stains in plant tissues by freeze-substitution and resin-embedding. J Microsc 142: 63–70
Duddridge JA, Read DJ (1984) The development and ultrastructure of ectomycorrhizas l. Ectomycorrhizal development on pine in the field. New Phytol 96: 565–573
Fischer JMC, Peterson CA, Bols NC (1985) A new fluorescent test for cell vitality using calcofluor white M2R. Stain Technol 60: 69–79
Grenville DJ, Peterson RL, Ashford AE (1986) Synthesis in growth pouches of mycorrhizae betweenEucalyptus pilularis and several strains ofPisolithus tinctorius. Aust J Bot 34: 95–102
Gunning BES, Hughes JE (1976) Quantitative assessment of symplastic transport of pre-nectar intro trichomes ofAbutilon nectaries. Aust J Plant Physiol 3: 619–637
Harley JL, Smith SE (1983) Mycorrhizal symbiosis. Academic Press, London New York
Kottke I, Oberwinkler F (1987) The cellular structure of the Hartig net: coenocytic and transfer cell-like organization. Nord J Bot 7: 85–95
Moon GJ, Peterson CA, Peterson RL (1984) Structural, chemical, and permeability changes following wounding in onion roots. Can J Bot 62: 2253–2259
Mueller WC, Greenwood AD (1978) The ultrastructure of phenolic-storing cells fixed with caffeine. J Exp Bot 29: 757–764
Nylund JE (1987) The ectomycorrhizal infection zone and its relation to acid polysaccharides of cortical cell walls. New Phytol 106: 505–516
—,Unestam T (1982) Structure and physiology of ectomycorrhizae l. The process of mycorrhiza formation in Norway sprucein vitro. New Phytol 91: 63–79
O'Brien TP, McCully ME (1981) The study of plant structure principles and selected methods. Termarcarphi Pty Ltd., Melbourne, Australia
Peterson CA (1987) The exodermal Casparian band of onion roots blocks the apoplastic movement of sulphate ions. J Exp Bot 38: 2068–2081
—,Emanuel ME, Humphreys GB (1981) Pathway of movement of apoplastic fluorescent dye tracers through the endodermis at the site of secondary root formation in corn (Zea mays) and broad bean (Vicia faba). Can J Bot 59: 618–625
—,Perumalla CJ (1984) Development of the hypodermal Casparian band in corn and onion roots. J Exp Bot 35: 51–57
Pigott CD (1982) Fine structure of mycorrhiza formed byCenococcum geophilum Fr. onTilia cordata Mill. New Phytol 92: 501–512
Pitman MG, Lüttge U (1983) The ionic environment and plant ionic relations. In:Lange OL, Nobel PS, Osmond CB, Ziegler H (eds) Physiological plant ecology III. Springer, Berlin Heidelberg New York Tokyo [Pirson A, Zimmermann MH (eds) Encyclopedia of plant physiology, vol 12 C, pp 5–34]
Reynolds ES (1963) The use of lead citrate at high pH as an electronopaque stain in electron microscopy. J Cell Biol 17: 208–212
Rose RW jr,Van Dyke CG, Davey CB (1981) Scanning electron microscopy of three types of ectomycorrhizae formed onEucalyptus nova-anglica in the southeastern United States. Can J Bot 59: 683–688
Salema R, Brandão I (1973) The use of PIPES buffer in the fixation of plant cells for electron microscopy. J Submicrosc Cytol 5: 79–96
Sands R, Theodorou C (1978) Water uptake by mycorrhizal roots of radiata pine seedlings. Aust J Plant Physiol 5: 301–309
—,Fiscus EL, Reid CPP (1982) Hydraulic properties of pine and bean roots with varying degrees of suberization, vascular differentiation and mycorrhizal infection. Aust J Plant Physiol 9: 559–569
Seviour RJ, Hamilton GA, Chilvers GA (1978) Scanning electron microscopy of the surface features of eucalypt mycorrhizas. New Phytol 80: 153–156
Spurr AR (1969) A low viscosity epoxy resin embedding medium for electron microscopy. J Ultrastruct Res 26: 31–43
Weerdenburg CA, Peterson CA (1984) Effect of secondary growth on the conformation and permeability of the endodermis of broad bean (Vicia fabd), sunflower (Helianthus annuus) and garden balsam (Impatiens balsamina). Can J Bot 62: 907–910
Willetts HJ, Bullock S (1988) Developmental biology of sclerotia. In:Read ND, Moore D (eds) Developmental biology of filamentous ascomycetes. Cambridge University Press, Cambridge
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Ashford, A.E., Peterson, C.A., Carpenter, J.L. et al. Structure and permeability of the fungal sheath in thePisonia mycorrhiza. Protoplasma 147, 149–161 (1988). https://doi.org/10.1007/BF01403343
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF01403343