Scanning electron microscopy of Fusarium oxysporum f.sp. lycopersici in xylem vessels of wilt-resistant and susceptible tomato plants

1980 ◽  
Vol 58 (22) ◽  
pp. 2360-2366 ◽  
Author(s):  
Erik L. Stromberg ◽  
Malcolm E. Corden
Keyword(s):  
Electron Microscopy ◽  
Hyphal Growth ◽  
Susceptible Host ◽  
Vessel Elements ◽  
Host Pathogen ◽  
Race 1 ◽  
Perforation Plates ◽  
Susceptible Tomato ◽  
Scanning Electron ◽  
Pathogen Combinations

Vessels in stems of 'Jefferson' (race 1 resistant and race 2 susceptible) and 'Bonny Best' (race 1 and 2 susceptible) tomato cultivars inoculated with Fusarium oxysporum f.sp. lycopersici race 1 or 2 were examined by scanning electron microscopy. Four days after inoculation of Jefferson with conidia of race 1, the inoculum conidia and resultant hyphae generally were collapsed, whereas in the susceptible host–pathogen combinations the inoculum conidia and hyphae appeared normal. Neither the plants of the resistant nor the susceptible host-pathogen combinations had perforation plates or tyloses within vessel elements capable of trapping conidia or effectively blocking hyphal growth. The perforation plates of all vessel elements are reduced to slightly lipped rims and thus provide unrestricted apertures for hyphal growth and conidial movement in the transpiration stream. In the susceptible host–pathogen combinations, mycelial growth often filled the vessels, but no sporulation was noted. Frequent lateral spread of the pathogen occurred between adjacent vessels through the bordered pit-pairs. Infrequent occurrence of tyloses and a lack of occlusions by tyloses in the resistant host–pathogen combination suggest that vascular wilt resistance within the stem is not due primarily to physical containment of the pathogen in the vessels. Collapsed conidia and hyphae in the resistant host–pathogen combination suggests that fungitoxic materials in the vessels suppress the pathogen and contribute to resistance.

The Distribution and Structure of Pits Between Vessels and Imperforate Tracheary Elements in Angiosperm Woods

IAWA Journal ◽  
2008 ◽  
Vol 29 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Yuzou Sano ◽  
Tomohiro Ohta ◽  
Steven Jansen
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Field Emission ◽  
Tracheary Element ◽  
Interspecific Variation ◽  
Tracheary Elements ◽  
Bordered Pits ◽  
Vessel Elements ◽  
Scanning Electron

This study focuses on the interspecific variation in the distribution and structure of pits between vessels and imperforate tracheary elements. Specimens from the outer sapwood of eight species, in which vessel elements are frequently in contact with fibres and/or tracheids, were prepared using two different techniques and examined by field-emission scanning electron microscopy. In three species in which vessels are surrounded by vasicentric tracheids and/or fibres with distinctly bordered pits, pit pairs frequently occurred in walls between vessels and imperforate tracheary elements. In the five species in which vessels are in contact with fibres with indistinctly bordered pits, no or very few pit pairs were present, and blind pits were often found. Blind pits were exclusively present in vessel elements in some species, while they were restricted to imperforate tracheary elements in other species. The nature of vessel to imperforate tracheary element pitting appears to depend on tracheary element specialization.

Wall Sculpturing in Vessel Elements of Juglans Species of the United States

IAWA Journal ◽  
2008 ◽  
Vol 29 (2) ◽  
pp. 153-160
Author(s):  
Young Geun Eom ◽  
Ohkyung Kwon ◽  
Robert B. Hanna ◽  
Robert W. Meyer
Keyword(s):  
Electron Microscopy ◽  
United States ◽  
Scanning Electron Microscopy ◽  
Vessel Wall ◽  
The United States ◽  
Diagnostic Value ◽  
Black Walnut ◽  
Large Vessel ◽  
Vessel Elements ◽  
Scanning Electron

Wall sculpturing in the vessel elements of some Juglans species of the United States, four black walnuts (J. major, J. nigra, J. microcarpa (= J. rupestris), and J. californica) and one butternut (J. cinerea), was investigated through light and scanning electron microscopy. This feature showed various forms such as helical and reticulate thickenings, and thickening-like structures formed by coalescent pit apertures and large vessel to ray pits. Light to prominent wall sculpturing occurred regularly in black walnuts but fine and indistinctive wall sculpturing was observed rarely in butternut. Thus, vessel wall sculpturing was of some diagnostic value for separating black walnut from butternut.

SEM Studies on Vessels in Ferns. 8. Platyzoma

1999 ◽  
Vol 47 (2) ◽  
pp. 277 ◽  
Author(s):  
Sherwin Carlquist ◽  
Edward L. Schneider ◽  
Kevin F. Kenneally
Keyword(s):  
Water Availability ◽  
Secondary Wall ◽  
Selective Advantage ◽  
Wall Material ◽  
Perforation Plate ◽  
Potential Value ◽  
Wide Range ◽  
Vessel Elements ◽  
Perforation Plates ◽  
Scanning Electron

Using scanning electron microscopy (SEM), vessels are demonstrated for roots and rhizomes of Platyzoma microphyllum R.Br. Because vessels are not in simple linear series, but have tips in contact with tips of other vessels, vessel elements may have several end walls, and each of these can bear a perforation plate. Vessels in roots are narrow, but have wide perforations. In rhizomes, perforation plates have a wide range of morphology. The most notable of these involves displacement and, frequently, fusion of adjacent bars of secondary wall material, so that large perforations tend to alternate with narrow perforations or with two or three fused bars. Porose pit membranes are present in narrower perforations. The presence of wide perforations achieved by means of bar displacement characterises not merely Platyzoma, but other ferns as well: Microgramma and Phlebodium. These three genera of ferns experience marked fluctuation in water availability, so that not only are vessels of potential value for rapid conduction during brief periods of water availability, but the presence of perforation plates conducive to such rapid conduction is of theoretical selective advantage as well. Stelar fibres that bear crystals on external surfaces of walls are reported for roots of Platyzoma. Such fibres have not been reported hitherto for ferns.

A Technique for Observing the Exterior Morphology of Intact Vessel Conduits

IAWA Journal ◽  
1983 ◽  
Vol 4 (2-3) ◽  
pp. 113-117
Author(s):  
Douglas J. Gardner ◽  
Fred W. Taylor
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Vessel Elements ◽  
Scanning Electron

A technique for examining the exterior of vessels by scanning electron microscopy is described. Features of vessels such as the union of vessel elements, the association of adjacent vessels, length of vessels, and deviations of vessels from their axial course can be studied.

Pathogenesis of Human Hair Defects

1974 ◽  
Vol 32 ◽  
pp. 12-13
Author(s):  
P.S. Porter ◽  
T. Aoyagi ◽  
R. Matta
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Human Hair ◽  
Standard Techniques ◽  
Scanning Electron

Using standard techniques of scanning electron microscopy (SEM), over 1000 human hair defects have been studied. In several of the defects, the pathogenesis of the abnormality has been clarified using these techniques. It is the purpose of this paper to present several distinct morphologic abnormalities of hair and to discuss their pathogenesis as elucidated through techniques of scanning electron microscopy.

The Critical Point Drying Method Applied to Scanning Electron Microscopy of L-929 Cells

1970 ◽  
Vol 28 ◽  
pp. 278-279
Author(s):  
Charles TurnbiLL ◽  
Delbert E. Philpott
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
Surface Tension ◽  
Critical Point ◽  
Freeze Drying ◽  
Attractive Alternative ◽  
Crystal Formation ◽  
Critical Point Drying ◽  
Time Required ◽  
Scanning Electron

The advent of the scanning electron microscope (SCEM) has renewed interest in preparing specimens by avoiding the forces of surface tension. The present method of freeze drying by Boyde and Barger (1969) and Small and Marszalek (1969) does prevent surface tension but ice crystal formation and time required for pumping out the specimen to dryness has discouraged us. We believe an attractive alternative to freeze drying is the critical point method originated by Anderson (1951; for electron microscopy. He avoided surface tension effects during drying by first exchanging the specimen water with alcohol, amy L acetate and then with carbon dioxide. He then selected a specific temperature (36.5°C) and pressure (72 Atm.) at which carbon dioxide would pass from the liquid to the gaseous phase without the effect of surface tension This combination of temperature and, pressure is known as the "critical point" of the Liquid.

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