Abstracts
Abstract
Light and transmission electron microscopy observations of staghorn sumac plants inoculated or naturally infected with Fusarium oxysporum f. sp. callistephi are reported. One aspect of infection was the presence of large intercellular masses of opaque matter (OM) in middle lamellae between ray cells and/or fibres, often bypassing several intercellular areas; similar OM confluent with the intercellular OM also occurred in secondary walls and in the periphery of numerous cells. A gradual increase in the abundance of the OM in host tissues vertically from the inoculation point and then radially was noted over infection time and was related to host wall and cell alterations. In the region of recently deposited tissue, the OM was associated with pronounced cell hyperplasia and hypertrophy. The OM was delimited by thin, compact bands, and when it was less compact, displayed opaque particles and other fine structures. No indications were obtained that it contained or had contained intact or altered organelles. The DNA probe bound to OM in middle lamellae and in cell periplasmic areas, and to material of a similar texture lining vessel walls. Samples from Fusarium-infected plants, incubated on an agar medium before fixing to determine from which elements the pathogens could develop, displayed bodies as the sole elements present in mature xylem cells and in intercellular areas. These bodies were delimited by membranous structures and profiles of a wall layer and contained opaque particles and areas of fine structures. Certain inter- or intracellular fungal cells in the same tissue frequently had similar content. In the light of these observations it is proposed that the OM is primarily of a pathogen rather than of a host origin.
Keywords:
- DNA labelling with a complexed monoclonal antibody,
- fungal wall irregularities,
- Fusarium wilt,
- vessel wall lining material
Résumé
On rapporte des observations en microscopie (photonique et électronique à transmission) de l’infection de plants de vinaigrier inoculés ou naturellement infectés par le Fusarium oxysporum f. sp. callistephi. L’un des aspects étudiés concerne la présence de matière opaque (MO) s’étant infiltrée dans les lamelles mitoyennes divisant les cellules de rayons et des fibres ou entre celles-ci, y longeant plusieurs espaces intercellulaires. Des liens ont été observés entre la MO intercellulaire et celle présente à l’occasion dans les parois secondaires et les espaces périplasmiques des cellules hôtes. Il y a eu augmentation graduelle de la MO vers l’écorce comme vers le sommet de la tige, et des altérations pariétales et cellulaires reliées à cette matière en fonction du temps après l’inoculation. On a noté dans la zone externe du xylème, en présence de la MO, l’hypertrophie et l’hyperplasie des cellules. La MO était encadrée par des lamelles minces et compactes, et, lorsque moins dense, elle est révélée contenir des particules opaques et autres fines structures; aucun indice de la présence antérieure ou actuelle d’organites intacts ou altérés dans la MO n’a été relevé. Cette MO, comme celle d’apparence semblable accolée aux parois vasculaires, a capté l’anticorps monoclonal contre l'ADN complexée à l’or colloïdal. Dans les plants atteints de la fusariose, placés sur un milieu de culture gélosé avant d’être fixés pour y déceler les formes particulières de l’agent pathogène présentes, seuls des corps bien définis se trouvaient dans les cellules du xylème rendu à maturité et dans les espaces intercellulaires. Ces corps étaient entourés de structures membranaires ou d’amorces de parois et pourvus de particules opaques et d’îlots de fines structures. Certaines cellules du champignon présentes dans ou entre les cellules dans le même tissu, montraient le même genre de contenu. C0 la faveur de ces observations, nous postulons que la matière en question provient d’abord de l’agent pathogène et non de l’hôte.
Mots clés:
- Anomalies de la paroi fongique,
- fusariose,
- marquage cytochimique pour l'ADN avec un anticorps monoclonal,
- recouvrements des parois vasculaires.
Appendices
References
- Atsatt, P.R. 2003. Fungus propagules in plastids: the mycosome hypothesis. Int. Microbiol. 6 : 1-21.
- Carothers, Z.B. 1973. Studies of spermatogenesis in the Hepaticae. IV. On the blepharoplast of Blasia. Am. J. Bot. 60 : 819-828.
- Chamberland, H. 1994. Gold labeling methods for the ultrastructural localization of host wall and pathogen components. Pages 1-11 in O. Petrini and G.B. Ouellette (eds.), Host wall alterations by parasitic fungi. APS Press, The American Phytopathological Society, St. Paul, MN, USA.
- Chamberland, H., and G.B. Ouellette. 1977a. Formes d’inclusions osmiophiles dans les cellules de Ceratocystis ulmi. Can. J. Bot. 55 : 695-710.
- Chamberland, H., and G.B. Ouellette. 1977b. Caractéristiques ultrastructurales de Ceratocystis ulmi en milieux naturel et artificiel. Can. J. Bot. 55 : 1579-1598.
- Charest, P.M., G.B. Ouellette, P. Blais, and H. Chamberland. 2004. Irregular growth forms and cell wall modifications, polygalacturonase detection, and endocell formation in Fusarium oxysporum f.sp. radicis-lycopersici infecting tomato plants, as studied ultrastructurally and cytochemically. Mycol. Prog. 3 : 137-150.
- Garrison, F., F. Mariat, K.S. Boyd, and H. Fromentin. 1977. Ultrastructural observations of an unusual osmiophilic body in the hyphae of Sporothrix schenckii and Ceratocystis stenoceras. Ann. Microbiol. (Institut Pasteur) 128B : 319-337.
- Nicole, M., K. Ruel, and G.B. Ouellette 1994. Fine morphology of fungal structures involved in host wall alteration. Pages 13-30 in O. Petrini and G.B. Ouellette (eds.), Host wall alterations by parasitic fungi. APS Press, The American Phytopathological Society, St. Paul, MN, USA.
- Ouellette, G.B. 1978. Light and electron microscope studies on cell wall breakdown in American elm xylem tissues infected with Dutch elm disease. Can. J. Bot. 56 : 2666-2693.
- Ouellette, G.B., and R.P. Baayen. 2000. Peculiar structures occurring in vessel walls of the susceptible carnation cultivar Early Sam infected with Fusarium oxysporum f. sp. dianthi. Can. J. Bot. 78 : 270-277.
- Ouellette, G.B., and D. Rioux. 1992. Anatomical and physiological aspects of resistance to Dutch elm disease. Pages 257-307 in R.A. Blanchette and A.R. Biggs (eds.), Defense mechanisms of woody plants against fungi. Springer-Verlag, Berlin, Germany.
- Ouellette, G.B., and D. Rioux. 1993. Alterations of vessel elements and reactions of surrounding tissues in the DED syndrome. Pages 255-292 in M.B. Sticklen and J.L. Sherald (eds.), Dutch elm disease research: cellular and molecular approaches. Springer-Verlag, New York, USA.
- Ouellette, G.B., N. Méthot, H. Chamberland, C. Côté, and J.-G. Lafontaine. 1995. Cytology of irregular growth forms of Ophiostoma ulmi and Ophiostoma novo-ulmi growing through millipore filter membranes and sterilized elm wood sections. Can. J. Microbiol. 41: 1095-1110.
- Ouellette, G.B., H. Chamberland, A. Goulet, M. Lachapelle, and J.-G. Lafontaine. 1999a. Fine structure of the extracellular sheath and cell walls in Ophiostoma novo-ulmi growing on various substrates. Can. J. Microbiol. 45 : 582-597.
- Ouellette, G.B., R.P. Baayen, M. Simard, and D. Rioux. 1999b. Ultrastructural and cytochemical study of colonization of xylem vessel elements of susceptible and resistant Dianthus caryophyllus by Fusarium oxysporum f. sp. dianthi. Can. J. Bot. 77 : 644-663.
- Ouellette, G.B., R.P. Baayen, M. Simard, and D. Rioux. 2002. Reactions of paratracheal cells of resistant and susceptible carnation (Dianthus caryophyllus) cultivars to vascular invasion by Fusarium oxysporum f.sp. dianthi. New Phytol. 156 : 113-128.
- Ouellette, G.B., D. Rioux, M. Simard, and M. Cherif. 2004a. Ultrastructural and cytochemical studies of hosts and pathogens in some fungal wilt diseases: retro- and introspection towards a better understanding of DED. In L. Gil, A. Solla, and G.B. Ouellette (eds.), New approaches to elm conservation. Investig. Agrar.: Sist. Recur. For. 13 : 119-143.
- Ouellette, G.B., R.P. Baayen, D. Rioux, and M. Simard. 2004b. Peculiar ultrastructural characteristics of fungal cells and of other elements apposed to and in vessel walls in plants of a susceptible carnation cultivar, infected with Fusarium oxysporum f.sp. dianthi race 2. Phytoprotection 85 : 121-138.
- Ouellette, G.B., D. Rioux, M. Simard, and R.P. Baayen. 2004c. Occurrence of paracrystalloids and their particles in resistant and susceptible carnation plants infected with Fusarium oxysporum f.sp. dianthi race 2. Phytoprotection 85 : 139-151.
- Ouellette, G.B., D. Rioux, M. Simard, H. Chamberland, M. Cherif, and R.P. Baayen. 2004d. Ultrastructure of the alveolar network and its relation to coating on vessel walls in elms infected with Ophiostoma novo-ulmi and in other plants affected with similar wilt diseases. In L. Gil, A. Solla, and G.B. Ouellette (eds.), New approaches to elm conservation. Investig. Agrar.: Sist. Recur. For. 13 : 147-160.
- Ouellette, G.B., M. Cherif, M. Simard, and L. Bernier. 2005. 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. Phytoprotection 86 : 157-174.
- Park, P., H. Ishii, Y. Adachi, S. Kanematsu, H. Ieki, and S. Umemoto. 2000. Infection behavior of Venturia nashicolai, the cause of scab on Asian pear. Phytopathology 90 : 1209-1216.
- Renzaglia, K.S., S.B. Dengate, S.J. Schmitt, and J.G. Duckett. 2002. Novel features of Equisetum arvense spermatozoids insights into pteridophyte evolution. New Phytol. 154 : 159-174.
10.7202/010906ar