Anatomical and Physiological Aspects of Resistance to Dutch Elm Disease

Ouellette, G. B.; Rioux, Danny

doi:10.1007/978-3-662-01642-8_13

Cited by 51 publications

(56 citation statements)

References 86 publications

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“…Tyloses are the vascular occlusions in many infected plants, such as oak (Quercus spp.) with oak wilt (Struckmeyer et al, 1958;Blaedow and Juzwik, 2010), American elm (Ulmus americana) with Dutch elm disease (Ouellette and Rioux, 1992;Rioux et al, 1995), and hop (Humulus lupulus) infected with Verticillium spp. (Talboys, 1958).…”

Section: Impact Of Vascular Occlusions On Hydraulic Conductivity Of Gmentioning

confidence: 99%

Vascular Occlusions in Grapevines with Pierce’s Disease Make Disease Symptom Development Worse

et al. 2013

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Vascular occlusions are common structural modifications made by many plant species in response to pathogen infection. However, the functional role(s) of occlusions in host plant disease resistance/susceptibility remains controversial. This study focuses on vascular occlusions that form in stem secondary xylem of grapevines (Vitis vinifera) infected with Pierce's disease (PD) and the impact of occlusions on the hosts' water transport and the systemic spread of the causal bacterium Xylella fastidiosa in infected vines. Tyloses are the predominant type of occlusion that forms in grapevine genotypes with differing PD resistances. Tyloses form throughout PD-susceptible grapevines with over 60% of the vessels in transverse sections of all examined internodes becoming fully blocked. By contrast, tylose development was mainly limited to a few internodes close to the point of inoculation in PD-resistant grapevines, impacting only 20% or less of the vessels. The extensive vessel blockage in PD-susceptible grapevines was correlated to a greater than 90% decrease in stem hydraulic conductivity, compared with an approximately 30% reduction in the stems of PD-resistant vines. Despite the systemic spread of X. fastidiosa in PD-susceptible grapevines, the pathogen colonized only 15% or less of the vessels in any internode and occurred in relatively small numbers, amounts much too small to directly block the vessels. Therefore, we concluded that the extensive formation of vascular occlusions in PD-susceptible grapevines does not prevent the pathogen's systemic spread in them, but may significantly suppress the vines' water conduction, contributing to PD symptom development and the vines' eventual death.

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Section: Impact Of Vascular Occlusions On Hydraulic Conductivity Of Gmentioning

confidence: 99%

Vascular Occlusions in Grapevines with Pierce’s Disease Make Disease Symptom Development Worse

et al. 2013

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“…Labelling of tylosis walls for pectin and cellulose was equivalent to that observed in elms (Rioux et al 1998). The areas containing cells with very opaque content and thickened walls, surrounding groups of vessel elements, also recalled those occurring in elms (American, Siberian, and different clones) and in non-hosts inoculated with the Dutch elm disease (DED) pathogen (Et-Touil et al 2005;Ouellette and Rioux 1992;Rioux and Biggs 1994). Vessel secondary walls also appeared to be modified as in elms (Ouellette 1981b).…”

Section: Discussionmentioning

confidence: 59%

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

Ouellette

Chérif

Simard

2006

phyto

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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.Diverses réactions cellulaires ont été observées chez des plants de vinaigrier inoculés par le Fusarium oxysporum f. sp. callistephi. Ces effets ont été notés au moyen de la microscopie photonique et électronique à transmission et par des tests cytochimiques. Ainsi, on a observé la formation de nombreux canaux de latex dans le liber et de thylles dans les éléments de vaisseaux, des épaississements ou autres modifications des parois cellulaires, des cloisons adventives dans certaines cellules et de l’hyperplasie et de l’hypertrophie cellulaires dans certains tissus. Les parois des thylles se sont marquées pour la pectine et la cellulose, sauf les couches lucides apparemment subérisées présentes dans plusieurs de ces thylles. Ces couches étaient également présentes dans les cellules de la couche médullaire ainsi que dans plusieurs cellules de parenchyme et même des fibres. Des barrières de protection se sont formées et elles étaient composées de cellules de parenchyme avec des parois épaissies et à contenu de forte densité et de fibres avec des parois additionnelles dites gélatineuses. Des altérations pariétales prononcées, reliées à de la matière opaque, se trouvaient dans ces cellules ou dans les parois avoisinantes. Plusieurs particules interreliées occupaient certaines cellules infectées pourvues de seulement quelques traces de cytoplasme altéré. Tel qu’observée en microscopie photonique, une zone de prolifération de cellules plus ou moins bien différenciées était visible à la marge extérieure du xylème. Du côté de la moelle et de la couche médullaire, une multiplication accrue de cellules provenant de ces tissus a également été notée. Ces masses tissulaires inusitées avaient...

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“…observations). In line with this possibility, the blisterlike networks in vessel lumina could likewise have originated from latex configurations and differed from the alveolar networks observed in elms infected with Dutch elm disease (Ouellette and Rioux 1992;Ouellette et al 2004e). However, the networks of thin bands, free and extending into vessel lumina or as part of the VWLM, also occurred and, as the alveolar network in elms, were associated with vessel wall alterations.…”

Section: Discussionmentioning

confidence: 81%

Histopathology of Fusarium wilt of staghorn sumac (Rhus typhina) caused by Fusarium oxysporum f. sp. callistephi race 3. I. Modes of tissue colonization and pathogen peculiarities

Ouellette

Chérif

Simard

et al. 2006

phyto

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Light and transmission electron microscope studies of naturally infected or inoculated staghorn sumac plants by Fusarium oxysporum f. sp. callistephi race 3 are reported. Diverse extrinsic material (including latex in some instances) or elements occurred in vessel lumina. Some of this material labelled for pectin, often in association with tyloses, as did other opaque matter in paratracheal cells, related to alterations of their protective layer. Pronounced alterations of pit membranes of bordered pits occurred, with their outer portions disrupted into bodies of opaque matter, strongly labelled for cellulose, and their middle portions as unlabelled shreds. Similarly labelled opaque bodies occasionally occurred on vessel walls and lumina. Direct penetration of host cell secondary walls by the pathogen occurred, but these were degraded to any extent only following intramural invasion. Vessel walls, at all stages of infection, were lined with variously structured matter: in their thinnest forms, by single or paired, equidistant or widely spaced opaque bands, and in their thickest forms as alternating opaque and less opaque layers. Other thin elements, often enclosing opaque material, vesicular structures, or occasionally particles of ribosomal appearance were also delineated by similar but frequently infolded bands. These elements were sometimes observed to be confluent with fungal cells and to label for chitin. Many fungal elements were bound by only a thin or defective lucent wall layer, practically unlabelled for chitin, or by a locally thickened, labelled one; labelling for this substrate was also frequently associated with the fungal cell outer opaque wall layer or with some outer extracellular matter. Fine filamentous structures, connected to fungal cells, to the vessel lining matter, and to these other elements, extended into host walls. The lining itself generally did not label for cellulose or chitin. These observations are discussed in comparison with similar observations made regarding other wilt diseases that we have studied.

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Anatomical and Physiological Aspects of Resistance to Dutch Elm Disease

Cited by 51 publications

References 86 publications

Vascular Occlusions in Grapevines with Pierce’s Disease Make Disease Symptom Development Worse

Vascular Occlusions in Grapevines with Pierce’s Disease Make Disease Symptom Development Worse

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

Histopathology of Fusarium wilt of staghorn sumac (Rhus typhina) caused by Fusarium oxysporum f. sp. callistephi race 3. I. Modes of tissue colonization and pathogen peculiarities

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