Ontogeny and fine structure of effective root nodules of the autumn olive (Elaeagnus umbellata)

1987 ◽  
Vol 65 (1) ◽  
pp. 80-94 ◽  
Author(s):  
William Newcomb ◽  
Dwight Baker ◽  
John G. Torrey
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Root Nodules ◽  
Freeze Fracture ◽  
Wall Layer ◽  
Void Space ◽  
Elaeagnus Umbellata ◽  
Autumn Olive ◽  
Clear Area ◽  
Glycogen Particles

An ultrastructural study of effective root nodules of the autumn olive (Elaeagnus umbellata Thunb.) demonstrated the presence of hyphal and vesicular forms of the actinomycete endophyte. No sporangial forms of the endophyte were observed within these nodules. The hyphae contained septa, prominent nucleoid regions, and many ribosomes. The endophytic vesicles were initially nonseptate and then became multichambered as a result of the inward growth of complete and incomplete septa. Glycogen particles were numerous in nonseptate and early stages of septate endophytic vesicle formation and in adjacent hyphae but were absent in more developed stages of septate endophytic vesicles. The endophytic vesicles also contained prominent nucleoid areas, vesicular mesosomes, and crystalline-like striated bodies. A capsule, probably derived from host Golgi cisternae and profiles of dilated rough endoplasmic reticulum, surrounded both forms of the endophyte. The endophytic vesicle cell walls consisted of an outer layer continuous with the hyphal cell wall, a middle clear area or “void space,” and an electron-dense inner layer. The “void space” of the endophyte cell wall was resolved into many thin laminae by freeze–fracture microscopy. The laminae were presumed to be different from the outermost cell wall layer because they were washed out in the solvents used in preparing specimens for the TEM.

Electron microscopic observations of infection threads in driselase treated nodules of Astragalus sinicus

1986 ◽  
Vol 32 (12) ◽  
pp. 947-952 ◽  
Author(s):  
Shiro Higashi ◽  
Kazuya Kushiyama ◽  
Mikiko Abe
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Plant Cell Wall ◽  
Root Nodules ◽  
Morphological Characteristics ◽  
Enzyme Treatment ◽  
Vascular Bundles ◽  
Electron Microscopic ◽  
Astragalus Sinicus ◽  
Infection Threads

The morphological characteristics of infection threads in the root nodules of Astragalus sinicus were examined by scanning and transmission electron microscopy. The infection threads, epidermal cell walls, and vascular bundles of the nodule were not altered when a nodule was treated with driselase (a plant cell wall degrading enzyme), although the cell walls of meristematic and bacteroid-including zones were completely decomposed by the enzyme treatment. Some infection threads were funnel shaped at the site of attachment of the infection thread to the host cell wall.

High-pressure freezing improves quantitative and qualitative structural data in the actinomycete microsymbiont frankia

1993 ◽  
Vol 51 ◽  
pp. 110-111
Author(s):  
R. Howard Berg
Keyword(s):  
High Pressure ◽  
Plant Root ◽  
Root Nodules ◽  
Freeze Fracture ◽  
Freeze Substitution ◽  
High Pressure Freezing ◽  
Void Space ◽  
En Bloc ◽  
Tem Analysis

Symbiotic plant root nodules containing the nitrogen-fixing bacterium Frankia occur on a variety of woody shrubs and trees. Ever since the first micrographs of freeze substituted cells of Frankia in culture were published there has been impetus to see if freeze substitued nodule tissue will improve imaging of Frankia in vivo. High pressure freezing/freeze substitution (HPFS) accomplishes this.Frankia is an actinomycete that fixes N2 in a specialized multicellular, spherical structure termed the “symbiotic vesicle” that is surrounded by a multilamellate envelope (MLE) comprised of lipids. Early work based on MLE birefringence suggested the MLE was a O2 diffusion barrier, thereby protecting nitrogenase from O2- inactivation. Recently this has been challenged by freeze fracture data. Traditionally it has been assumed that the MLE is electrontranslucent because the lamina of the MLE are extracted by dehydration solvents, producing the “void space”--an extraction artifact hindering TEM analysis of MLE structure.En bloc staining with chromic acid stains the MLE, showing that the MLE is present after exposure to dehydration solvents and that the void space results from tissue shrinkage in the symbiotic vesicle (Figure 1).

Chemical and ultrastructural studies on the distribution of sporopolleninlike biopolymers in six genera of lichen phycobionts

1985 ◽  
Vol 63 (12) ◽  
pp. 2221-2230 ◽  
Author(s):  
Ueli Brunner ◽  
Rosmarie Honegger
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Resistant Cell ◽  
Wall Layer ◽  
Conclusive Evidence ◽  
The Other ◽  
Chemical Methods ◽  
Ultrastructural Studies ◽  
Cell Wall Polymer ◽  
Infrared Absorption Spectra

Cell walls of cultured lichen phycobionts of the genera Coccomyxa, Elliptochloris, Myrmecia, Pseudochlorella, Trebouxia, and Trentepohlia were investigated with cytological and chemical methods with regard to the presence or absence of trilaminar sheaths and (or) resistant biopolymers. Trilaminar cell wall layers occurred in Coccomyxa, Elliptochloris, Myrmecia, and (less distinctly) Pseudochlorella species. A biopolymer highly resistant to nonoxidative degradation by phosphoric acid occurred only in the isolated and vigorously extracted cell walls of Coccomyxa and Elliptochloris species. The walls of all the other phycobionts, including Myrmecia and Pseudochlorella, were totally degraded, showing that a trilaminar wall layer is not conclusive evidence for the presence of a resistant cell wall polymer. The infrared absorption spectra of the degradation-resistant cell wall polymer of Coccomyxa and Elliptochloris species were not fully identical with those of natural sporopollenins. When the widely used, but chemically less appropriate acetolysis method was applied to either entire cells or isolated but not fully extracted cell walls of Coccomyxa, Elliptochloris, Myrmecia, Pseudochlorella, Trebouxia, and Trentepohlia species, they all yielded acetolysis-resistant residues whose infrared spectra resembled natural sporopollenin.

scholarly journals Cytological Aspects of the Mycobiont–Phycobiont Relationship in Lichens

1984 ◽  
Vol 16 (2) ◽  
pp. 111-127 ◽  
Author(s):  
Rosmarie Honegger
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Wall Layer ◽  
Distinct Pattern ◽  
Homogeneous Material ◽  
Wall Surface ◽  
Surface Layers ◽  
Thin Sectioning ◽  
Cytological Features ◽  
Mother Cell Wall

AbstractCytological aspects of the mycobiont-phycobiont contact were investigated in the lichen species Peltigera aphthosa, Cladonia macrophylla, Cladonia caespiticia and Parmelia tiliacea by means of freeze-etch and thin sectioning techniques, and by replication of isolated fragments of myco- and phycobiont cell walls.In the symbiotic state of the mycobionts investigated a thin outermost wall layer with a distinct pattern was observed mainly in the hyphae contacting phycobiont cells and in the upper medullary layer. No comparable structures were noted on the hyphal surface of the cultured mycobionts of the Cladonia and Parmelia species investigated. A distinct rodlet layer was found on the hyphal surface of the mycobiont of Peltigera aphthosa, while mycobionts of Cladonia macrophylla, C. caespiticia and Parmelia tiliacea had a mosaic of small, irregular ridges, each corresponding in its size to a bundle of rodlets on the outermost wall layer. Comparable surface layers have been described in aerial hyphae of a great number of non-lichenized fungi.The rodlet layer of the mycobiont wall surface of Peltigera aphthosa adheres tightly to the outermost layer of the sporopollenin-containing cell wall of the Coccomyxa phycobiont. Mature trebouxioid phycobiont cells of the Cladonia and Parmelia species investigated in the symbiotic state had an outermost wall layer which was structurally indistinguishable from the tessellated surface layer of the mycobiont cells. A rodlet pattern was detected in the outermost wall layer of Trebouxia autospores still surrounded by the cellulosic mother cell wall. In mature Trebouxia cells the bundles of rodlets became increasingly covered by a homogeneous material, and thus attained the same tessellated pattern which was observed on the mycobiont wall surface. No comparable structures were found on the wall surface after culturing the Trebouxia phycobionts axenically in liquid media. Confluence of the tessellated surface layers of fungal and algal origin was noted at the contact sites of growing hyphal tips and young Trebouxia cells.The possible correlations between these cytological features and published immunological data on the cell surface of cultured and symbiotic lichen myco- and phycobionts are discussed.

Ultrastructure of Nocardia-like variants of Mycobacterium smegmatis and chemical composition of the basal cell wall layer

1977 ◽  
Vol 23 (12) ◽  
pp. 1723-1732 ◽  
Author(s):  
R. J. Hawley ◽  
Nora Mann ◽  
T. Imaeda
Keyword(s):  
Cell Wall ◽  
Mycobacterium Smegmatis ◽  
Freeze Fracture ◽  
Basal Layer ◽  
Wall Layer ◽  
Negative Staining ◽  
Diaminopimelic Acid ◽  
Positive Staining ◽  
Mycolic Acids ◽  
Mutant Strains

Mycobacterium smegmatis, its orange-red – pigmented (OR) variants, and back mutant strains were examined by electron microscopy using ultrathin sectioning, negative or positive staining, and freeze-fracture – etching methods. The parental and back mutant strains showed almost identical ultrastructures. Specifically, thick ramified fibers measuring about 15 nm in diameter were always visible in the positively stained cell wall, although they were not readily visualized with negative staining or freeze-fracture-etching. In contrast, the cell walls of OR variants contained fibrous networks measuring about 11 nm in diameter, which could be observed by positive and negative staining as well as freeze-fracture-etching. Although cytoplasmic structures appeared similar among the four strains examined, mesosomes were significantly more abundant in the OR variants. The basal layer of the cell wall obtained as a phenol residue consisted of a dense membranous matrix containing scattered fibrous structures in the parental and back mutant strains, and fibrous networks in the OR variants. Chemical analyses showed that the basal layers of all four strains contained the same neutral sugars, amino sugars, and amino acids, i.e., arabinose, galactose, muramic acid, glucosamine, alanine, glutamic acid, and diaminopimelic acid. The α-branched β-hydroxylated fatty acids contained in the basal layers differ among the four strains, however, with nocardomycolic acids being present in the OR variants and mycolic acids in the parental and back mutant strains. Our previous conclusion that OR variants of M. smegmatis have characteristics similar to those of nocardia is supported by the present study.

The effect of glucose concentration and light on thallospore ultrastructure in Ellisomyces anomalus (Thamnidiaceae, Mucorales)

1984 ◽  
Vol 62 (12) ◽  
pp. 2677-2687 ◽  
Author(s):  
Gordon W. Beakes ◽  
Galba M. Campos-Takaki ◽  
Massonori Takaki
Keyword(s):  
Freeze Fracture ◽  
Spore Wall ◽  
Wall Layer ◽  
Structural Differences ◽  
Low Glucose ◽  
Electron Microscopical ◽  
Gilbertella Persicaria ◽  
Effect Of Glucose ◽  
Glycogen Particles ◽  
Fracture Electron

The development of chains of thallospores in the mucoraceous fungus Ellisomyces anomalus has been examined using scanning, thin section, and freeze-fracture electron microscopical techniques. The development and cytology of spores formed on high-glucose (HG, 4.0%) and low-glucose (LG, 0.06%) media, under both light and dark conditions, have been compared. The vegetative hyphae of spores on LG media accumulate glycogen particles in their cytoplasm but contain very little lipid. The cytoplasm of HG hyphae is packed with lipid globules. The thallospores are delimited by septa, which as in most other mucoraceous fungi are perforated by plasmodesmatalike pit connections. A thick secondary (spore) wall layer is accreted as the spores swell. Although mature thallospores on LG and HG media are similar in their external morphology, they show internal differences. HG spores are thicker walled and contain abundant lipid and glycogen reserves. LG spores contain relatively little lipid and are more highly vacuolate. The only structural differences observed between the carotene-rich, light-grown spores and their dark-grown counterparts is an increase in lipid globule electron density and an overall enhancement of membrane staining properties. The mature thallospores secede from the parent hyphae by both shizolytic (septum splitting) and rhexolytic (circumcissile hyphal splitting) mechanisms. From a developmental standpoint it is suggested the thallospores of Ellisomyces resemble thallic arthric conidia (arthrospores), simiar to those produced by Mucor rouxii, more closely than true chlamydospores, such as those produced by Gilbertella persicaria and Mucor mucedo.

Sporopollenin in the cell walls of Coccomyxa and Myrmecia phycobionts of various lichens: an ultrastructural and chemical investigation

1981 ◽  
Vol 59 (12) ◽  
pp. 2713-2734 ◽  
Author(s):  
Rosmarie Honegger ◽  
Ueli Brunner
Keyword(s):  
Mother Cell ◽  
Cell Walls ◽  
Freeze Fracture ◽  
Thick Layer ◽  
Outer Wall ◽  
Wall Layer ◽  
Middle Part ◽  
Wall Structure ◽  
Thin Sections ◽  
Ir Spectrophotometry

Symbiotic and cultivated Myrmecia phycobionts of Baeomyces rufus and Coccomyxa phycobionts of five different asco- and basidio-lichens were investigated with cytological and chemical methods. The cell wall structure of the free-living type species Coccomyxa dispar was compared with that of the lichen phycobionts.Three different wall layers were observed in all Coccomyxa and Myrmecia cells investigated. An innermost, variably thick layer is amorphous in structure and is built up mainly by Golgi-derived hemicelluloses. An outer wall layer, uniformly thick, appears electron dense in thin sections and exhibits short, probably cellulosic fibrils embedded in an amorphous matrix in freeze-fracture preparations. Beyond these two wall layers is an outermost trilaminar wall layer of uniform thickness in all species investigated. It contains sporopollenin in its electron-transparent, rigid middle part; proteinlike particles are embedded in an amorphous, carbohydrate-containing matrix on its electron-dense inner and outer surfaces. IR spectrophotometry of acetolysis-resistant material yielded data comparable with those of other sporopollenin-containing algal walls, although the Coccomyxa and Myrmecia sporopollenin did not dissolve in chromic acid. The trilaminar layer is not lysed during or after autospore formation. Persistent mother cell walls were detected in all lichen thalli investigated, as well as in the culture medium of isolated phycobionts. Persistent mother cell walls were also found in the gelatinous sheath of Coccomyxa dispar.This type of wall structure affords protection against fungal parasitism and may be a significant factor in the success of some lichens and some other symbiotic systems.

scholarly journals Cell Wall Layer Induced in Xylem Fibers of Flax Upon Gravistimulation Is Similar to Constitutively Formed Cell Walls of Bast Fibers

2021 ◽  
Vol 12 ◽  
Author(s):  
Anna Petrova ◽  
Liudmila Kozlova ◽  
Oleg Gorshkov ◽  
Alsu Nazipova ◽  
Marina Ageeva ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Secondary Cell Wall ◽  
Wall Layer ◽  
Cell Wall Layer ◽  
Wall Deposition ◽  
Secondary Cell Walls ◽  
Phloem Fibers ◽  
Xylem Fibers ◽  
Cell Wall Deposition

In the fibers of many plant species after the formation of secondary cell walls, cellulose-enriched cell wall layers (often named G-layers or tertiary cell walls) are deposited which are important in many physiological situations. Flax (Linum usitatissimum L.) phloem fibers constitutively develop tertiary cell walls during normal plant growth. During the gravitropic response after plant inclination, the deposition of a cellulose-enriched cell wall layer is induced in xylem fibers on one side of the stem, providing a system similar to that of tension wood in angiosperm trees. Atomic force microscopy (AFM), immunochemistry, and transcriptomic analyses demonstrated that the G-layer induced in flax xylem fibers was similar to the constitutively formed tertiary cell wall of bast (phloem) fibers but different from the secondary cell wall. The tertiary cell walls, independent of tissue of origin and inducibility, were twice as stiff as the secondary cell walls. In the gravitropic response, the tertiary cell wall deposition rate in xylem was higher than that of the secondary cell wall. Rhamnogalacturonan I (RG-I) with galactan side chains was a prominent component in cellulose-rich layers of both phloem and xylem flax fibers. Transcriptomic events underlying G-layer deposition in phloem and xylem fibers had much in common. At the induction of tertiary cell wall deposition, several genes for rhamnosyltransferases of the GT106 family were activated in xylem samples. The same genes were expressed in the isolated phloem fibers depositing the tertiary cell wall. The comparison of transcriptomes in fibers with both inducible and constitutive tertiary cell wall deposition and xylem tissues that formed the secondary cell walls is an effective system that revealed important molecular players involved in the formation of cellulose-enriched cell walls.

Fine structure of root hair infection leading to nodulation in the Frankia–Alnus symbiosis

1986 ◽  
Vol 64 (2) ◽  
pp. 292-305 ◽  
Author(s):  
A. M. Berry ◽  
L. McIntyre ◽  
M. E. McCully
Keyword(s):  
Cell Wall ◽  
Root Hair ◽  
Root Nodules ◽  
Structural Features ◽  
Wall Layer ◽  
Transfer Cell ◽  
Wall Formation ◽  
Root Hair Cell ◽  
Successful Infection ◽  
Root Hair Infection

Root hair infection by Frankia (Actinomycetales) is the means by which nitrogen-fixing root nodules are initiated upon the actinorhizal host, Alnus rubra. Structural details of the infectious process and the changes in host root hair cells are demonstrated at the prenodule stage for the first time using light and transmission electron microscopy. The Frankia hypha is the infective agent, extending from the rhizosphere through the root hair wall in a highly deformed region of the hair. There is no evidence of pleomorphism of the Frankia hypha. The primary wall fibrils of the root hair appear disorganized at the site of penetration. There is extensive secondary wall formation in the infected hair. At the site of penetration, root hair cell wall ingrowths occur that are structurally consistent with transfer cell wall formation. The ingrowths are continuous with the encapsulating wall layer surrounding the Frankia hypha The host cytoplasm is rich in ribosomes, secretory products, and organelles, including Golgi bodies, mitochondria, plastids, and profiles of endoplasmic reticulum. In an aborted infection sequence, some structural features of the host response to Frankia are observable, while other aspects of successful infection do not occur. Limited transfer cell wall is formed at the site of near infection. The root hair cytoplasm is senescent, however, and a callosic plug appears to surround the pathway of infection.

Juvenile and Compression Wood Cell Wall Layers Differ in Lignin Structure in Norway Spruce and Scots Pine

IAWA Journal ◽  
2008 ◽  
Vol 29 (1) ◽  
pp. 47-57 ◽  
Author(s):  
Eija Kukkola ◽  
Pekka Saranpää ◽  
Kurt Fagerstedt
Keyword(s):  
Cell Wall ◽  
Norway Spruce ◽  
Scots Pine ◽  
Cell Walls ◽  
Compression Wood ◽  
Wood Cell Wall ◽  
Outer Part ◽  
Wall Layer ◽  
Mature Wood ◽  
Normal Wood

Dibenzodioxocin, an 8-ring substructure of lignin identified in the mid- 1990's, is known to occur in softwood cell walls especially in the S3-layers of normal wood. In this study the lignin substructure was immunolocalised in juvenile and mature wood as well as in different degrees of compression wood of Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.). In juvenile wood of Norway spruce, dibenzodioxocin was hardly present in the tracheid cell wall, while in Scots pine some dibenzodioxocin was found evenly distributed in the S2-layers. In mature normal wood, dibenzodioxocin was localised in the S3-layers in both Scots pine and Norway spruce. In contrast, in compression wood tracheids of Scots pine, where the S3-layer is not present, dibenzodioxocin was found in the S1-layers and in the outer part of the S2-layers, while in Norway spruce the innermost cell wall layer showed a strong signal. These findings support the idea that in mature wood the condensed dibenzodioxocin structure is formed in Norway spruce at the end of lignification, when the supply of monolignols and probably also hydrogen peroxide is diminishing. The reasons for Scots pine juvenile and compression wood showing a different pattern of dibenzodioxocin labelling is discussed.

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