Ultrastructure of the host–pathogen interface in Arabidopsis thaliana leaves infected by the downy mildew Hyaloperonospora parasitica

2004 ◽  
Vol 82 (7) ◽  
pp. 1001-1008 ◽  
Author(s):  
C W Mims ◽  
E A Richardson ◽  
B F Holt III ◽  
J L Dangl
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Arabidopsis Thaliana ◽  
High Pressure ◽  
Cell Wall ◽  
Host Cell ◽  
Hyaloperonospora Parasitica ◽  
Transmission Electron ◽  
Host Pathogen ◽  
Host Cell Wall

Transmission electron microscopy was used to examine the host–pathogen interface in Arabidopsis thaliana (L.) Heynh. leaves infected by the biotrophic downy mildew pathogen Hyaloperonospora parasitica (Pers.:Fr.) Constant. Both conventionally fixed as well as high-pressure frozen samples were examined. Excellent preservation of the host–pathogen interface was obtained in many of our high-pressure frozen samples and provided information not available in conventionally fixed samples. Mature haustoria of H. parasitica were distinctly pyriform in shape. A small collar of host cell wall material surrounded the neck of each haustorium near the host cell wall penetration site. The presence of callose in collars was demonstrated using immunogold labeling with a monoclonal antibody specific for (1→3)-β-glucans. The body of each haustorium was ensheathed by an invaginated portion of the invaded host-cell plasma membrane known as the extrahaustorial membrane. Lying between this membrane and the haustorial wall was a layer of electron-dense material known as the extrahaustorial matrix (EHM). The EHM typically was thicker at the distal end of a haustorium than at the proximal end. The surface of the EHM covered by the extrahaustorial membrane was highly irregular in outline. Considerable vesicular activity was observed in association with the extrahaustorial membrane.Key words: transmission electron microscopy, high-pressure freezing, haustoria, Peronospora parasitica.

Development of primary germ tubes by conidia of Blumeria graminis f.sp. hordei on leaf epidermal cells of Hordeum vulgare

2002 ◽  
Vol 80 (10) ◽  
pp. 1121-1125 ◽  
Author(s):  
H H Edwards
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Hordeum Vulgare ◽  
Host Cell ◽  
Germ Tube ◽  
Tube Wall ◽  
Blumeria Graminis ◽  
Transmission Electron ◽  
Host Cell Wall ◽  
Germ Tubes

Development of primary germ tubes from conidia of Blumeria graminis f.sp. hordei on primary leaf segments of Hordeum vulgare was investigated from 3 to 13 h postinoculation (hpi) using transmission electron microscopy. By 3 hpi, the primary germ tube wall that makes contact with the host cuticle develops a small protrusion that breaches the host cuticle and touches the host cell wall but does not penetrate any further. This protrusion is the cuticular peg. From 3 to 13 hpi, the cuticular peg swells, becomes quite electron dense, and finally develops a loose fibrillar texture. The structure of the primary germ tube with the terminal cuticular peg is consistent with the hypothesis that it allows the conidium to absorb water and solutes present in the host cell wall.Key words: powdery mildew, barley, ultrastructure.

scholarly journals Chemical composition, anatomy, lignin distribution, and cell wall structure of Malaysian plant waste fibers

BioResources ◽  
2006 ◽  
Vol 1 (2) ◽  
pp. 220-232 ◽  
Author(s):  
H. P. S. Abdul Khalil ◽  
M. Siti Alwani ◽  
A. K. Mohd Omar
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Chemical Composition ◽  
Cell Wall Structure ◽  
Wall Structure ◽  
Anatomical Characteristics ◽  
Lignin Distribution ◽  
Transmission Electron ◽  
Palm Frond

The chemical composition, anatomical characteristics, lignin distribution, and cell wall structure of oil palm frond (OPF), coconut (COIR), pine-apple leaf (PALF), and banana stem (BS) fibers were analyzed. The chemical composition of fiber was analyzed according to TAPPI Methods. Light microscopy (LM) and transmission electron microscopy (TEM) were used to observe and determine the cell wall structure and lignin distribution of various agro-waste fibers. The results revealed differences in anatomical characteristics, lignin distributions, and cell wall structure of the different types of fibers investigated. Nevertheless, transmission electron microscopy (TEM) micrographs have confirmed that the well wall structure, in each case, could be described in terms of a classical cell wall structure, consisting of primary (P) and secondary (S 1 , S 2 , and S 3 ) layers.

Colonization of Sphagnum cells by Lyophyllum palustre

1985 ◽  
Vol 63 (4) ◽  
pp. 757-761 ◽  
Author(s):  
E. Untiedt ◽  
K. Müller
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Light Microscopy ◽  
Host Cell ◽  
Cell Walls ◽  
Transmission Electron ◽  
Scanning Electron

Lyophyllum palustre (Peck) Singer, a basidiomycete (Tricholomataceae) parasitizing Sphagnum, was examined for points of contact between hyphae and Sphagnum cells with the help of light microscopy, scanning electron microscopy, and transmission electron microscopy. Results indicate that the fungus attacks Sphagnum cells by penetrating cell walls and altering host cell protosplasm. In addition, the formation of additional partitioning cell walls in attacked living Sphagnum cells was observed.

Crystal structures of high-pressure phases formed in Si by laser irradiation

Microscopy ◽  
2018 ◽  
Vol 67 (1) ◽  
pp. 30-36
Author(s):  
Hiroyuki Iwata ◽  
Daisuke Kawaguchi ◽  
Hiroyasu Saka
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Pressure ◽  
Laser Beam ◽  
Crystal Structures ◽  
Laser Irradiation ◽  
Pulse Laser ◽  
Transmission Electron ◽  
Micro Cracks ◽  
Pressure Phase

Abstract Internal modification induced in Si by a permeable pulse laser was investigated by transmission electron microscopy. A laser induced modified volume (LIMV) was a cylindrical rod along the track of a laser beam with the head at the focus of the laser beam. In the LIMV, beside voids, dislocations, micro-cracks and what had been supposed to be an unidentified high-pressure phase (hpp) of Si were observed in LIMV. The so-called ‘hpp’ was identified mostly as diamond Si.

Shock Synthesis of Nanocrystalline High -Pressure Phases in Semiconductors by High-Velocity Thermal Spray

2000 ◽  
Vol 638 ◽  
Author(s):  
R. Goswami ◽  
J. Parise ◽  
H. Herman ◽  
S. Sampath ◽  
R. Gambino ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Pressure ◽  
Thermal Spray ◽  
High Velocity ◽  
Metastable Phase ◽  
High Energy ◽  
Metastable Phases ◽  
Transmission Electron ◽  
Average Size

AbstractShock synthesis of nanocrystalline Si, Ge and CdTe was accomplished using high- velocity thermal spray. Si or Ge powders were injected into a high energy flame, created by a thermal spray gun, where the particles melt and accelerate to impact on a substrate. The shock wave generated by the sudden impact of the droplets propagated through the underlying deposits, which induces a phase transition to a high pressure form. The decompression of the high-pressure phase results in the formation of several metastable phases, as evidenced by transmission electron microscopy and x-ray diffraction studies. The peak pressure is estimated to be ≈23GPa with a pulse duration of 1-5 ns. Transmission electron microscopy revealed that the metastable phases of Si with a size range of 2 to 5 nm were dispersed within Si-I. In Ge, a metastable phase, ST-12, was observed. This is a decompression product of Ge-II which possesses the β-Sn type of structure. In the case of CdTe, a fine dispersion of hexagonal CdTe particles, embedded in cubic-CdTe with an average size of 2 nm was obtained.

Histopathology of Fusarium wilt of staghorn sumac (Rhus typhina) caused by Fusarium oxysporum f. sp. callistephi race 3. III. Host cell and tissue reactions

2006 ◽  
Vol 87 (1) ◽  
pp. 17-27 ◽  
Author(s):  
Guillemond B. Ouellette ◽  
Mohamed Cherif ◽  
Marie Simard
Keyword(s):  
Cell Wall ◽  
Fusarium Oxysporum ◽  
Host Cell ◽  
Cross Wall ◽  
Tissue Proliferation ◽  
Host Cytoplasm ◽  
Transmission Electron ◽  
Host Cell Wall ◽  
Tissue Reactions ◽  
Rhus Typhina

Abstract Various cell reactions occurred in staghorn sumac plants inoculated with Fusarium oxysporum f. sp. callistephi. Light and transmission electron microscopy observations and results of cytochemical tests showed: 1) increased laticifers and latex production in the phloem; 2) tylosis formation; 3) host cell wall modifications, including appositions or other cell wall thickenings; and 4) unusual cross wall formation in some cells, and cell hypertrophy and hyperplasia. Tylosis walls labelled for pectin and cellulose and many displayed inner suberin-like layers. These layers were also noted in cells of the medullary sheath and in many cells with dense content and thickened walls in the barrier zones that had formed. These zones also contained fibres with newly-formed gelatinous-like layers. In the vicinity of these cells, host cell walls were frequently altered, associated with opaque matter. Many small particles present in chains also occurred in some of these cells, which contained only remnants of host cytoplasm. Light microscopy observations showed that pronounced tissue proliferation and aberrant cells occurred in the outer xylem in the infected plants. Unusual neoplasmic tissue also formed from cells surrounding the pith and medullary sheath, and it spanned directly across the pre-existing xylem tissue and burst as large mounds on the stems.

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