Characteristics of Extracellular Adhesions Produced During<i>Saprolegnia Ferax</i>Secondary Zoospore Encystment and Cystospore Germination

Durso, Lisa M.; Lehnen, Larry P.; Powell, Martha J.

doi:10.1080/00275514.1993.12026328

Cited by 8 publications

(14 citation statements)

References 20 publications

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“…Cytochemical studies have localized carbohydrates within smaller vesicles in the peripheral cytoplasm of zoospores of Chytriomyces species (Dorward andPowell 1983, Powell 1994) indicative of vesicles capable of forming an encasement layer or releasing adhesion material at encystment. While the function of these vesicles remains unclear, we hypothesize they might play a role in cellular adhesion to a substrate before zoospore encystment (Durso et al 1993).…”

Section: Discussionmentioning

confidence: 99%

“…Ecology.-The diverse organisms of Chytridiales occupy specific ecological niches, including soils, aquatic systems, the terrestrial/aquatic interface (Willoughby 1961) and epiphytic mats of soil-like material in the canopy of temperate and tropical rainforests (Powell 1993, Longcore 2005. R. phycophilum is a soil chytrid, but its apparent association with a green alga raises questions about potential roles for chytrids in terrestrial habitats.…”

Section: Discussionmentioning

confidence: 99%

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Rhizidium phycophilum, a new species in Chytridiales

Picard¹,

Letcher²,

Powell

2009

Mycologia

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Molecular and ultrastructural investigations are revealing unrealized diversity among chytrids as the taxonomic revision of order Chytridiales (Chytridiomycota) progresses. During a biodiversity survey of soil-inhabiting chytrids in Australia an undescribed chytrid was isolated from a soil sample collected in a cool temperate rainforest of New South Wales, Australia. Combined zoospore ultrastructure analysis and molecular phylogenetic analyses of partial LSU rRNA and ITS1-5.8S-ITS2 sequences demonstrated this chytrid was a new species within Chytridiales and possessed distinctive zoospore architecture previously unknown. Herein we delineate a new Rhizidium species in Chytridiales based on molecular monophyly and unique subcellular organization of the zoospore.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Rhizidium phycophilum, a new species in Chytridiales

Picard¹,

Letcher²,

Powell

2009

Mycologia

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“…Selective encystment, germination, and appressorium formation by zoospores, the infective stage of the parasite, largely determines its host range, as is the case with many zoosporic parasites (Deacon and Donaldson 1993). Like many oomycetes (Durso et al 1993) L. giganteum zoospores drop their flagella following the induction of encystment. General features of the external morphology of this parasite (Brey and Lebrun 1987) were confirmed in this report.…”

Section: Discussionmentioning

confidence: 99%

Regulation of attachment, germination, and appressorium formation by zoospores ofLagenidium giganteum and related oomycetes by chitin, chitosan, and catecholamines

et al. 1997

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Summary. Lagenidium giganteum (Oomycetes: Lagenidiales), a facultative parasite of mosquito larvae, infects the larval stage of most species of mosquitoes and a very limited number of alternate hosts. Host infection by this and other members of Oomycetes is initiated by motile, laterally biflagellate zoospores. Chemical bases for the various degrees of host specificity exhibited by these parasites is not known, but presumably involves receptors on the zoospore surface recognizing compounds either secreted by or on the surface of their hosts. Surface topography had no detectable effect on L. giganteum encystment or appressorium formation. Scanning electron microscopy documented the detachment of flagella during zoospore encystment. Bulbous knobs at the basal end of the detached flagellum were interpreted as encysting zoospores dropping the axoneme and/or the basal body and associated structures to which flagella are attached. Multiple signals appear to be involved in the initial steps ofL. giganteum host invasion. Zoospores of this parasite did not encyst on powdered preparations of chitin or chitosan (deacetylated chitin). Upon dissolution of chitosan in dilute acid followed by drying these solutions to form thin, transparent films, zoospores readily encysted. The degree of reacetylation of these films and the spacing of acetylated and deacetylated residues had no significant effect on zoospore encystment. Zoospores of a strain of Lagenidiurn myophilurn isolated from marine shrimp, that also infects mosquito larvae, encysted on chitosan films. No encystment of spores of the plant parasite Phytophthora capsici was observed on chitin or chitosan films. Simulation of cuticle sclerotization by incubating chitosan films with different catecholamines and tyrosinase significantly reduced zoospore encystment. Zoospores that encysted on chitosan films did not germinate in distilled water. Germination could be induced by adding microgram quantities of bovine serum albumin or proteins secreted by motile zoospores into the water, and to a lesser degree by some amino acids, but not by various cations. Zoospores encysted and germinated on the pupal stage of some mos-*Correspondence and reprints: Botany Department, Box 351330, University of Washington, Seattle, WA 98195, U.S.A. quito species. Appressoria were occasionally fort-ned, but most subsequently sent out another mycelial branch, apparently without attempting to pierce the pupal cuticle. Methylation of pupal exuviae with ethereal diazomethane or methanol/HC1 significantly increased zoospore encystment. Modification of chitin by catecholamines, lipids and protein on the epicuticular larval surface all affected host invasion.

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“…33) and does not bind lectins. In Saprolegnia a similar adhesive pad is derived from the kinetosome-associated vesicles (K2-bodies; Powell 1989, 1991 ;Durso et al 1993;Burr and Beakes 1994). The latter contain proteinaceous material, sulphydryl bond containing carbohydrates and release a material that binds the lectin wheat germ agglutinin (WGA), specific for N-acetyl glucosamine containing sugars Powell 1988, 1989).…”

Section: Species Specificmentioning

confidence: 98%

The application of spore surface features in defining taxonomic versus ecological groupings in oomycete fungi

Beakes¹,

Burr²,

Wood³

et al. 1995

Can. J. Bot.

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The origin and structure of cyst surface components in oomycete fungi are described in relation to evaluating their use as taxonomic markers. The ontogeny, biochemistry, and morphological variations in the populations of peripheral vesicles that occur in the zoospores of members of the Peronosporomycetidae and Saprolegniomycetidae, which are discharged upon encystment to give rise to spore surface components, are reviewed. The use of the ornamentation of the cyst coat to define genera within the Saprolegniomycetidae and as an indicator of geographical and host-specific clones within a species of Saprolegnia are reviewed. The cyst coat of the fish pathogen Saprolegnia parasitica shows considerable morphological diversity that appears to be independent of the geographic origin of isolates. There is an indication that a group of isolates with variable, relatively short, spines form a separate clone from those with larger hooped bundles. The monoclonal antibody probes that have been generated to spore surface components of Saprolegnia parasitica, Pythium aphanidermaturn, and Phytophthora cinnamomi are summarized and their use in defining taxonomic groups reviewed. The antibodies show different levels of specificity ranging from isolate-to order-specific reactions. The degree of specificity can be influenced in some cases by the immunoassay method used. These studies indicate that surface structures and molecules provide extremely versatile and valuable markers for use in oomycete taxonomy and phylogeny.Resume : Les auteurs dCcrivent l'origine et la structure des constituants de la surface des kystes chez les champignons oomycktes, en relation avec 1'Cvaluation de leur utilisation comme marqueurs taxonomiques. Les auteurs revoient l'ontogknie, la biochimie et les variations morphologiques des populations des vCsicules pCriphCriques qui surviennent chez les zoospores des membres des pCronosporomycCtideae et des saprolCgniomycCtideae, lesquelles sont reldchCes au moment de l'enkystement pour donner naissance aux composantes de la surface des spores. 11s revoient Cgalement l'utilisation des ornementations de l'enveloppe des kystes pour dCfinir les genres de saprolCgniomycCtideae et comme indicateur des clones giographiques et spCcifiques l'hbte, pour une espkce de Saprolegnia donnCe. L'enveloppe des kystes du pathogkne des poissons, le Saprolegnia parasitica, montre une diversit6 morphologique considkrable qui semble indipendante de l'origine gkographique des souches. 11 y a une indication qu'un groupe d'isolats munis de spinules variables et relativement courtes forme un clone distinct de ceux qui portent des faisceaux en arceaux. On rCsume les sondes i anticorps monoclonaux qui ont Ct C gCnCrCes pour les composantes de la surface sporale du Saprolegnia parasitica, du Pythium aphanidermaturn et du Phytophthora cinnamomi et on revoit leur utilisation pour la definition de groupes taxonomiques. Les anticorps montrent diffkrents niveaux de spCcificitC allant de reactions spCcifiques i l'isolat jusqu'i celle qui sont spCcif...

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Characteristics of Extracellular Adhesions Produced DuringSaprolegnia FeraxSecondary Zoospore Encystment and Cystospore Germination

Cited by 8 publications

References 20 publications

Rhizidium phycophilum, a new species in Chytridiales

Rhizidium phycophilum, a new species in Chytridiales

Regulation of attachment, germination, and appressorium formation by zoospores ofLagenidium giganteum and related oomycetes by chitin, chitosan, and catecholamines

The application of spore surface features in defining taxonomic versus ecological groupings in oomycete fungi

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