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

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.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...

Histological Changes in Mango Seedlings Following Infection with Ceratocystis manginecans, the Cause of Mango Decline

“…1999; Rajput and Rao 2007). Invasion of xylem by fungal mycelium and subsequent production of tyloses have been reported for many fungal–host interactions, including Ceratocystis species (Hessburg and Hansen 1987; Ouellette et al. 2006; Rajput and Rao 2007).…”

“…Discolouration of wood is common following infection and colonization by some pathogens (Ballard et al 1984;Uzunovic et al 1999;Rajput and Rao 2007). Invasion of xylem by fungal mycelium and subsequent production of tyloses have been reported for many fungal-host interactions, including Ceratocystis species (Hessburg and Hansen 1987;Ouellette et al 2006;Rajput and Rao 2007).…”

Tissue invasion and alteration in eggplant infected with Verticillium dahliae: A light and transmission electron microscopy study

“…The still labelled outer pit membrane region indicates that breakdown products or adsorption of other components did not interfere with the reaction, as was the case for the walls of altered and reacting cells showing increased opacities. Hence, if the opaque vessel occluding components or VWLM corresponded to breakdown products of pit membranes, they would still label for cellulose, a fact that was observed only once in infected staghorn sumac (Ouellette et al 2005a). Otherwise, the cellulose-labelled substrate in vessel lumina had a more lucent appearance, which in the present case was traceable to detached or broken portions of secondary wall thickenings.…”

“…These were characterized by three demarcated layers: a shredded one, unlabelled for cellulose, a more compact and opaque cellulose-labelled layer, and the unlabelled VWLM layer. This type of alteration mirrored that of pit membranes of half-bordered pits in the metaxylem in DED affected elms and Fusariuminfected carnations (Ouellette 1978a(Ouellette , 1978bOuellette et al 1999Ouellette et al , 2004bOuellette et al , 2004cOuellette and Rioux 1993) and often of intertracheary pit membranes in staghorn sumac (Ouellette et al 2005a). In all instances, the term "swelling of pit membranes" should not apply, in our opinion, when it is primarily attributed to covering layers of extraneous matter, likely of a pathogen origin in most cases.…”

Tissue specific reactions of sorghum roots to the mycoherbicideFusariumoxysporumf. sp.strigaeversus the pathogenicF. proliferatum

“…This was unlike in the case of F. oxysporum f. sp. callistephi race 3 on staghorn sumac (Rhus typhina) where cell wall thickenings and tyloses in vessels were observed as cell reactions to invasion (Ouellette, Cherif, and Simard 2006).…”