A structural study of the interaction between the ectomycorrhizal fungus Pisolithus tinctorius and Pinus strobus roots

1983 ◽  
Vol 61 (4) ◽  
pp. 1185-1193 ◽  
Author(s):  
Y. Piché ◽  
R. L. Peterson ◽  
Melanie J. Howarth ◽  
J. André Fortin
Keyword(s):  
Light And Electron Microscopy ◽  
Cortical Cell ◽  
Middle Lamella ◽  
Pinus Strobus ◽  
Ectomycorrhizal Fungus ◽  
Pisolithus Tinctorius ◽  
Cortical Cells ◽  
Root Cells ◽  
Hartig Net ◽  
Limited Digestion

Stages in ectomycorrhizal development between the fungus Pisolithus tinctorius (Pers.) Coker & Couch and short roots of Pinus strobus L. were followed in growth pouches. Short roots from preinoculation through Hartig net formation were processed for light and electron microscopy. Fungal hyphae approaching the surface of roots have Thiéry-positive substances in their modified walls and in lomasomes, indicating the possibility of extracellular polysaccharide secretion. Hyphae grow between and beneath the flattened, tannin-filled superficial root cells and subsequently into the intercellular region of the cortex. A Hartig net several hyphae wide is formed, isolating the cortical cells from each other. Plasmodesmata were not observed in these cortical cells. Middle lamella material is always present around the intercellular hyphae, suggesting limited digestion by the hyphae. Cortical cell cytoplasm becomes necrotic in regions of mature Hartig net formation.

Structure and ontogeny of Betula alleghaniensis – Pisolithus tinctorius ectomycorrhizae

1990 ◽  
Vol 68 (3) ◽  
pp. 579-593 ◽  
Author(s):  
H. B. Massicotte ◽  
R. L. Peterson ◽  
C. A. Ackerley ◽  
L. H. Melville
Keyword(s):  
Root Hairs ◽  
Root Surface ◽  
Pisolithus Tinctorius ◽  
Initial Contact ◽  
Broad Host Range ◽  
Betula Alleghaniensis ◽  
Cortical Cells ◽  
Structural Modifications ◽  
Hartig Net ◽  
Primary Roots

The ontogeny and ultrastructure of ectomycorrhizae synthesized between Betula alleghaniensis (yellow birch) and Pisolithus tinctorius, a broad host range fungus, were studied to determine the structural modifications in both symbionts during ectomycorrhiza establishment. A number of stages, including initial contact of hyphae with the root surface, early mantle formation, and mature mantle formation, were distinguished. Interactions between hyphae and root hairs were frequent. As a paraepidermal Hartig net developed, root epidermal cells elongated in a radial direction, but wall ingrowths were not formed. Repeated branching of Hartig net hyphae resulted in extensive fine branches and the compartmentalization of hyphal cytoplasm. Nuclei and elongated mitochondria were frequently located in the narrow cytoplasmic compartments, and [Formula: see text] thickenings developed along walls of cortical cells in primary roots.

scholarly journals Domain-specific and cell type-specific localization of two types of cell wall matrix polysaccharides in the clover root tip.

1992 ◽  
Vol 118 (2) ◽  
pp. 467-479 ◽  
Author(s):  
M A Lynch ◽  
L A Staehelin
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Cellular Differentiation ◽  
Cortical Cell ◽  
Middle Lamella ◽  
Root Cap ◽  
Root Tip ◽  
Cortical Cells ◽  
Peripheral Cell ◽  
Clover Root

Using immunocytochemical techniques and antibodies that specifically recognize xyloglucan (anti-XG), polygalacturonic acid/rhamnogalacturonan I (anti-PGA/RG-I), and methylesterified pectins (JIM 7), we have shown that these polysaccharides are differentially synthesized and localized during cell development and differentiation in the clover root tip. In cortical cells XG epitopes are present at a threefold greater density in the newly formed cross walls than in the older longitudinal walls, and PGA/RG-I epitopes are detected solely in the expanded middle lamella of cortical cell corners, even after pretreatment of sections with pectinmethylesterase to uncover masked epitopes. These results suggest that in cortical cells XG and PGA/RG-I are differentially localized not only to particular wall domains, but also to particular cell walls. In contrast to their nonoverlapping distribution in cortical cells, XG epitopes and PGA/RG-I epitopes largely colocalize in the epidermal cell walls. The results also demonstrate that the middle lamella of the longitudinal walls shared by epidermal cells and by epidermal and cortical cells constitutes a barrier to the diffusion of cell wall and mucilage molecules. Synthesis of XG and PGA/RG-I epitope-containing polysaccharides also varies during cellular differentiation in the root cap. The differentiation of gravitropic columella cells into mucilage-secreting peripheral cells is marked by a dramatic increase in the synthesis and secretion of molecules containing XG and PGA/RG-I epitopes. In contrast, JIM 7 epitopes are present at abundant levels in columella cell walls, but are not detectable in peripheral cell walls or in secreted mucilage. There were also changes in the cisternal labeling of the Golgi stacks during cellular differentiation in the root tip. Whereas PGA/RG-I epitopes are detected primarily in cis- and medial Golgi cisternae in cortical cells (Moore, P. J., K. M. M. Swords, M. A. Lynch, and L. A. Staehelin. 1991. J. Cell Biol. 112:589-602), they are localized predominantly in the trans-Golgi cisternae and the trans-Golgi network in epidermal and peripheral root cap cells. These observations suggest that during cellular differentiation the plant Golgi apparatus can be both structurally and functionally reorganized.

Host microtubules in the Hartig net region of ectomycorrhizas, ectendomycorrhizas, and monotropoid mycorrhizas

2004 ◽  
Vol 82 (7) ◽  
pp. 938-946 ◽  
Author(s):  
Yukari Kuga-Uetake ◽  
Melissa Purich ◽  
Hugues B Massicotte ◽  
R. Larry Peterson
Keyword(s):  
Pinus Banksiana ◽  
Structural Changes ◽  
Close Association ◽  
Confocal Scanning Laser Microscopy ◽  
Fungal Colonization ◽  
Cortical Cells ◽  
Root Cells ◽  
Hartig Net ◽  
Confocal Scanning Laser ◽  
Wilcoxina Mikolae

Various categories of mycorrhizas are recognized primarily by the structural changes that occur between fungi and roots. In all mycorrhiza categories, cytological modifications of root cells accompany the establishment of the functional symbiosis, and among these are alterations in the organization of the cytoskeleton. Using immuno labelling combined with confocal scanning laser microscopy, this study documents changes in microtubules (MTs) in root cells of ectendomycorrhizas and monotropoid mycorrhizas; in addition, ectomycorrhizas were reinvestigated to determine the effect of fungal colonization on host root cells. In Pinus banksiana L. – Laccaria bicolor (Maire) Orton ectomycorrhizas, MTs were present in epidermal and cortical cells adjacent to the Hartig net. The remaining cortical MTs had a different organization when compared with those of cortical cells of control roots. MTs were present in Hartig net hyphae. In ectendomycorrhizas formed when roots of P. banksiana were colonized by the ascomycete, Wilcoxina mikolae var. mikolae Yang & Korf, MTs were present adjacent to intracellular hyphae and host nuclei, but few cortical MTs were present. MTs were present within Hartig net and intracellular hyphae. In field-collected roots of Monotropa uniflora L., MTs were associated with fungal pegs, intracellular extensions of inner mantle hyphae within epidermal cells. The close association between MTs and fungal pegs may be related to the formation of the highly branched host-derived wall that envelops each fungal peg. The development of exchange interfaces in the three systems studied involve changes in the organization of microtubules.Key words: cytoskeleton, microtubules, Hartig net, mycorrhizas, immunolocalization, confocal microscopy.

Technique for the observation of early morphological changes during ectomycorrhiza formation

1980 ◽  
Vol 58 (3) ◽  
pp. 361-365 ◽  
Author(s):  
J. André Fortin ◽  
Yves Piché ◽  
Maurice Lalonde
Keyword(s):  
Ectomycorrhizal Fungi ◽  
Morphological Changes ◽  
Pinus Strobus ◽  
Pisolithus Tinctorius ◽  
Hartig Net ◽  
Cenococcum Graniforme

Flat, transparent polyester growth pouches were used for synthesis of ectomycorrhizae on Pinus strobus seedlings. Typical ectomycorrhizae with mantle and Hartig net were obtained within 5 days after inoculation with Pisolithus tinctorius. An extensive extramatrical network of hyphae and hyphal strands could be observed within 15 days after ectomycorrhizae formation. The process was somewhat slower with Cenococcum graniforme. Other proven ectomycorrhizal fungi on P. strobus were unsuccessful in forming ectomycorrhizae under conditions used in these experiments.

Ontogeny of Eucalyptus pilularis – Pisolithus tinctorius ectomycorrhizae. I. Light microscopy and scanning electron microscopy

1987 ◽  
Vol 65 (9) ◽  
pp. 1927-1939 ◽  
Author(s):  
H. B. Massicotte ◽  
R. L. Peterson ◽  
A. E. Ashford
Keyword(s):  
Lateral Root ◽  
Lateral Roots ◽  
Ectomycorrhizal Fungus ◽  
Pisolithus Tinctorius ◽  
Broad Host Range ◽  
Lateral Root Development ◽  
First Order ◽  
Hartig Net ◽  
Ectomycorrhizal Roots ◽  
Eucalyptus Pilularis

Eucalyptus pilularis Sm. seedlings were grown in growth pouches and inoculated with the broad host range ectomycorrhizal fungus Pisolithus tinctorius (Pers.) Coker & Couch. External morphology and internal structure of all stages of ectomycorrhiza formation on first-order and second-order laterals were studied. The morphology of the ectomycorrhiza is dependent on the stage of lateral root development at the time of colonization by fungal hyphae. Emerging lateral roots are colonized by hyphae originating from the inner mantle of the parent root. The Hartig net does not spread internally from the parent root to the lateral root. All primary tissues of mycorrhizal lateral roots are differentiated close to the apical meristem. The epidermal cells undergo a marked increased in radial growth instead of the usual elongation in the axial plane. The hypodermis is a barrier to the penetration of hyphae so that Hartig net formation is paradermal only. Older portions of ectomycorrhizal roots show a degeneration of the epidermis, hypodermis, and cortex excluding the endodermis, and a proliferation of hyphae in these senescing tissues.

Structure and development of Pinus banksiana – Wilcoxina ectendomycorrhizae

1991 ◽  
Vol 69 (10) ◽  
pp. 2135-2148 ◽  
Author(s):  
Pamela F. Scales ◽  
R. L. Peterson
Keyword(s):  
Electron Microscopy ◽  
Pinus Banksiana ◽  
Cortical Cell ◽  
Root Surface ◽  
Cell Plasma Membrane ◽  
Cortical Cells ◽  
Hartig Net ◽  
Transmission Electron ◽  
Cell Plasma ◽  
Wilcoxina Mikolae

Seedlings of Pinus banksiana were grown in growth pouches and inoculated with Wilcoxina mikolae var. mikolae, Wilcoxina mikolae var. tetraspora, and Wilcoxina rehmii. Ectendomycorrhizae formed between P. banksiana and W. mikolae var. mikolae developed rapidly following inoculation. The mantle was of variable width, and a large amount of mucigel was evident on the root surface. Intracellular penetration of the cortical cells by hyphae occurred one to two cells distal to Hartig net formation. Both light and transmission electron microscopy revealed labyrinthic growth of Hartig net hyphae that were densely cytoplasmic during early penetration stages but became vacuolate as the association aged. Intracellular colonization of the cortex was extensive, with the hyphae highly branched and surrounded by an interfacial matrix and cortical cell plasma membrane. The external morphology and anatomy of ectendomycorrhizae formed between W. mikolae var. tetraspora and W. rehmii and P. banksiana were similar to those described for W. mikolae var. mikolae. Key words: ectendomycorrhizae, Wilcoxina, Pinus banksiana, intracellular, Hartig net, E-strain.

Infection by Phytophthora cinnamomi Rands of Roots of Eucalyptus calophylla R.Br. and Eucalyptus marginata Donn. ex Sm

1977 ◽  
Vol 25 (5) ◽  
pp. 483 ◽  
Author(s):  
N Malajczuk ◽  
AJ Mccomb ◽  
CA Parker
Keyword(s):  
Phytophthora Cinnamomi ◽  
Light And Electron Microscopy ◽  
Inhibitory Effect ◽  
Lateritic Soil ◽  
Root Damage ◽  
Mature Trees ◽  
Cortical Cells ◽  
Eucalyptus Marginata ◽  
Seedling Roots ◽  
Loam Soil

On lateritic podzolic soils in Western Australia Eucalyptus calophylla is resistant to Phytophthora cinnamomi whereas Eucalyptus marginata is susceptible and eventually killed by the pathogen. On loam soils both eucalypts are resistant. Possible mechanisms for resistance of E. calophylla in lateritic soil and the inhibitory action of loam soils were investigated. Aseptically raised eucalypt seedlings succumbed to infection in liquid culture tubes. The mechanism of infection was compared by light and electron microscopy which showed similar fungal invasion and penetration into roots of both eucalypt species. Vegetative hyphae initially penetrated intercellularly and proliferated rapidly within cortical and stelar tissue. Intracellular invasion of these tissues occurred 48hr after initial infection through dissolution of the host cell wall. Chlamydospores were formed within a number of cortical cells. Unsuberized roots of mature trees produced aseptically showed reactions to invasion similar to those of the eucalypt seedling roots. Suberized roots were not invaded. The addition of small quantities of lateritic soil to sterile sand so as to introduce soil micro-organisms without altering the chemical and physical status of the sand, and subsequent inoculation of the sand with P.cinnamomi, resulted in a reduction of root damage on both eucalypts when compared with seedlings raised in sterile sand. Roots of E.calophylla were less severely damaged than those of E.marginata. The addition of small quantities of loam soil significantly reduced root damage in seedlings of both species. These results parallel both pot experiments and field observations, and suggest that microorganisms of the rhizosphere may be an important factor in the resistance of E.calophylla to infection, and in the inhibitory effect of loam soil on P.cinnamomi.

Computing with Self-Excitatory Cliques: A Model and an Application to Hyperacuity-Scale Computation in Visual Cortex

1999 ◽  
Vol 11 (1) ◽  
pp. 21-66 ◽  
Author(s):  
Douglas A. Miller ◽  
Steven W. Zucker
Keyword(s):  
Visual Processing ◽  
Network Architecture ◽  
Early Stage ◽  
Cortical Cell ◽  
Pyramidal Cells ◽  
Direct Calculation ◽  
Formal Theory ◽  
Cortical Cells ◽  
Cell Counts ◽  
Spatiotemporal Response

We present a model of visual computation based on tightly inter-connected cliques of pyramidal cells. It leads to a formal theory of cell assemblies, a specific relationship between correlated firing patterns and abstract functionality, and a direct calculation relating estimates of cortical cell counts to orientation hyperacuity. Our network architecture is unique in that (1) it supports a mode of computation that is both reliable and efficent; (2) the current-spike relations are modeled as an analog dynamical system in which the requisite computations can take place on the time scale required for an early stage of visual processing; and (3) the dynamics are triggered by the spatiotemporal response of cortical cells. This final point could explain why moving stimuli improve vernier sensitivity.

Short-and long-term effects of cadmium on transmembrane electric potential (E m) in maize roots

Biologia ◽  
2006 ◽  
Vol 61 (1) ◽  
Author(s):  
Ján Pavlovkin ◽  
Miroslava Luxová ◽  
Ingrid Mistríková ◽  
Igor Mistrík
Keyword(s):  
Root Growth ◽  
Electric Potential ◽  
Time Course ◽  
Cumulative Effect ◽  
Significant Inhibition ◽  
Long Term Effects ◽  
Cortical Cells ◽  
Root Cells ◽  
Maize Roots ◽  
Atp Supply

AbstractIn this study, the effects of Cd on root growth, respiration, and transmembrane electric potential (E m) of the outer cortical cells in maize roots treated with various Cd concentrations (from 1 µM to 1 mM) for several hours to one week were studied. The E m values of root cells ranged between −120 and −140 mV and after addition of Cd they were depolarized immediately. The depolarization was concentration-dependent reaching the value of diffusion potential (E D) when the Cd concentration exceeded 100 µM. The values of E D ranged between −65 to −68 mV (−66 ± 1.42 mV). The maximum depolarization of E m was registered approx. 2.5 h after addition of Cd to the perfusion solution and in some cases, partial (Cd > 100 µM) or complete repolarization (Cd < 100 µM) was observed within 8–10 h of Cd treatment. In the time-dependent experiments (0 to 168 h) shortly after the maximum repolarization of E m a continuous concentration-dependent decrease of E m followed at all Cd concentrations. Depolarization of E m was accompanied by both increased electrolyte leakage and inhibition of respiration, especially in the range of 50 µM to 1 mM Cd, with the exception of root cells treated with 1 and 10 µM Cd for 24 and 48 h. Time course analysis of Cd impact on root respiration revealed that at higher Cd concentrations (> 50 µM) the respiration gradually declined (∼ 6 h) and then remained at this lowest level for up to 24 h.All the Cd concentrations used in this experiment induced significant inhibition of root elongation and concentrations higher than 100 µM stopped the root growth within the first day of Cd treatment. Our results suggest that Cd does not cause irreversible changes in the electrogenic plasma membrane H+ ATPase because fusicoccin, an H+ ATPase activator diminished the depolarizing effect of Cd on the E m. The depolarization of E m in the outer cortical cells of maize roots was the result of a cumulative effect of Cd on ATP supply, plasmalemma permeability, and activity of H+ ATPase.

Early Periderm Ontogeny in Fraxinuspennsylvanica, Ailanthusaltissima, Robiniapseudoacacia, and Pinusresinosa, Seedlings

1972 ◽  
Vol 2 (2) ◽  
pp. 135-143 ◽  
Author(s):  
G. A. Borger ◽  
T. T. Kozlowski
Keyword(s):  
Cell Layer ◽  
Cortical Cell ◽  
Cortical Cells ◽  
Mother Cells

The subepidermal cell layer was the site of origin of the first periderm in the hypocotyl and internodes of Fraxinuspennsylvanica and Ailanthusaltissima. In the hypocotyl of Robiniapsendoacacia, the first periderm arose in cortical cells near the phloem; in the internodes it originated in the subepidermal, second, or third cortical cell layer. The outermost cell layer of the pericycle gave rise to the first periderm in the hypocotyl of Pinusresinosa. In all four species, periderm appeared first near the base of the hypocotyl and developed acropetally. In A. altissima and R. pseudoaeacia, phellem mother cells were cut off by the phellogen. These subsequently divided to produce phellem cells. In F. pennsylvanica and P. resinosa, phellem cells were produced directly from the phellogen.

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