Zoospore Ultrastructure of Monoblepharis polymorpha

Mollicone, Marilyn R. Noyes; Longcore, Joyce E.

doi:10.2307/3760531

Cited by 15 publications

(8 citation statements)

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“…Zygorhizidium willei has two types of banded structures between the kinetosome and the large vesicle. These structures are similar to the rhizoplast observed in some chytrids in Rhizophlyctidales (Letcher et al 2008) or striated disk observed in some chytrids belonging to Monoblepharidales in Monoblepharidomycetes (Fuller & Reichle 1968, Reichle 1972, Mollicone & Longcore 1994, 1999. Both structures are distinct from the banded structures of Zygor.…”

Section: Zygorhizidium Sensu Latosupporting

confidence: 80%

Taxonomic revision of the genus Zygorhizidium: Zygorhizidiales and Zygophlyctidales ord. nov. (Chytridiomycetes, Chytridiomycota)

Seto

Wyngaert

Degawa

et al. 2020

Fungal Systematics and Evolution

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During the last decade, the classification system of chytrids has dramatically changed based on zoospore ultrastructure and molecular phylogeny. In contrast to well-studied saprotrophic chytrids, most parasitic chytrids have thus far been only morphologically described by light microscopy, hence they hold great potential for filling some of the existing gaps in the current classification of chytrids. The genus Zygorhizidium is characterized by an operculate zoosporangium and a resting spore formed as a result of sexual reproduction in which a male thallus and female thallus fuse via a conjugation tube. All described species of Zygorhizidium are parasites of algae and their taxonomic positions remain to be resolved. Here, we examined morphology, zoospore ultrastructure, host specificity, and molecular phylogeny of seven cultures of Zygorhizidium spp. Based on thallus morphology and host specificity, one culture was identified as Z. willei parasitic on zygnematophycean green algae, whereas the others were identified as parasites of diatoms, Z. asterionellae on Asterionella, Z. melosirae on Aulacoseira, and Z. planktonicum on Ulnaria (formerly Synedra). According to phylogenetic analysis, Zygorhizidium was separated into two distinct order-level novel lineages; one lineage was composed singly of Z. willei, which is the type species of the genus, and the other included the three species of diatom parasites. Zoospore ultrastructural observation revealed that the two lineages can be distinguished from each other and both possess unique characters among the known orders within the Chytridiomycetes. Based on these results, we accommodate the three diatom parasites, Z. asterionellae, Z. melosirae, and Z. planktonicum in the distinct genus Zygophlyctis, and propose two new orders: Zygorhizidiales and Zygophlyctidales.

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Section: Zygorhizidium Sensu Latosupporting

confidence: 80%

Taxonomic revision of the genus Zygorhizidium: Zygorhizidiales and Zygophlyctidales ord. nov. (Chytridiomycetes, Chytridiomycota)

Seto

Wyngaert

Degawa

et al. 2020

Fungal Systematics and Evolution

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“…4). 4), the most parsimonious phylogeny groups the Monoblepharidales closer to the "core chytrid clade" than the Blastocladiales, in agreement with both ultrastructural data (Barr 1981;Mollicone and Longcore 1994) and the phylogenies of Paquin et al (1997). Although the placement of the Monoblepharidales within the fungal phylogeny is not supported by bootstrap analysis (Fig.…”

Section: Relationship Of the Chytridiomycota To Other Fungisupporting

confidence: 66%

Molecular phylogenetics of the Chytridiomycota supports the utility of ultrastructural data in chytrid systematics

James¹,

Porter²,

Leander³

et al. 2000

Can. J. Bot.

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The chytrids (Chytridiomycota) are morphologically simple aquatic fungi that are unified by their possession of zoospores that typically have a single, posteriorly directed flagellum. This study addresses the systematics of the chytrids by generating a phylogeny of ribosomal DNA sequences coding for the small subunit gene of 54 chytrids, with emphasis on sampling the largest order, the Chytridiales. Selected chytrid sequences were also compared with sequences from Zygomycota, Ascomycota, and Basidiomycota to derive an overall fungal phylogeny. These analyses show that the Chytridiomycota is probably not a monophyletic group; the Blastocladiales cluster with the Zygomycota. Analyses did not resolve relationships among chytrid orders, or among clades within the Chytridiales, which suggests that the divergence times of these groups may be ancient. Four clades were well supported within the Chytridiales, and each of these clades was coincident with a group previously identified by possession of a common subtype of zoospore ultrastructure. In contrast, the analyses revealed homoplasy in several developmental and zoosporangial characters.Résumé : Les chytrides (Chytridiomycota) sont des champignons aquatiques morphologiquement simples qui se caractérisent par la présence de zoospores typiquement munies d'un unique flagelle dirigé vers l'arrière. Cette étude porte sur la systématique des chytrides en présentant une phylogénie basée sur les séquences de l'ADN ribosomale du gène codant pour la petite sous-unité, chez 54 chytrides, en mettant l'accent sur un échantillonage de l'ordre le plus important, les Chytridiales. Les auteurs ont également comparé des séquences sélectionnées de chytridiales avec des séquences provenant de Zygomycota, d'Ascomycota, et de Basidiomycota afin d'obtenir une phylogénie générale. Ces analyses montrent que le Chytridiomycota n'est probablement pas un groupe monophylétique; les Blastocladiales se regroupent avec le Zygomycota. L'analyse ne définit pas les relations entre les ordres de chytrides, ou entre les clades parmi les Chytridiales, ce qui suggère que les moments de divergences entre ces groupes pourraient être anciens. Quatre clades sont bien définis au sein des Chytridiales, et chacun de ces clades coïncide avec un groupe précédemment identifié par la possession d'un sous-type commun d'ultrastructures zoosporales. A l'opposé, les analyses révèlent la présence d'homoplasie chez plusieurs caractères au niveau du développement et des zoosporanges.

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“…Previous ultrastructural studies of Monoblepharidomycetes have focused on zoospores to infer phylogenetic relationships (Fuller and Reichle 1968;Reichle 1972;Gauriloff et al 1980a, b;Mollicone andLongcore 1994, 1999). Dolan and Fuller (1985) studied mitosis in Monoblepharella sp.…”

Section: Introductionmentioning

confidence: 99%

Cytology and molecular phylogenetics of Monoblepharidomycetes provide evidence for multiple independent origins of the hyphal habit in the Fungi

Dee

Mollicone²,

Longcore

et al. 2015

Mycologia

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The evolution of filamentous hyphae underlies an astounding diversity of fungal form and function. We studied the cellular structure and evolutionary origins of the filamentous form in the Monoblepharidomycetes (Chytridiomycota), an early-diverging fungal lineage that displays an exceptional range of body types, from crescent-shaped single cells to sprawling hyphae. To do so, we combined light and transmission electron microscopic analyses of hyphal cytoplasm with molecular phylogenetic reconstructions. Hyphae of Monoblepharidomycetes lack a complex aggregation of secretory vesicles at the hyphal apex (i.e. Spitzenkörper), have centrosomes as primary microtubule organizing centers and have stacked Golgi cisternae instead of tubular/fenestrated Golgi equivalents. The cytoplasmic distribution of actin in Monoblepharidomycetes is comparable to the arrangement observed previously in other filamentous fungi. To discern the origins of Monoblepharidomycetes hyphae, we inferred a phylogeny of the fungi based on 18S and 28S ribosomal DNA sequence data with maximum likelihood and Bayesian inference methods. We focused sampling on Monoblepharidomycetes to infer intergeneric relationships within the class and determined 78 new sequences. Analyses showed class Monoblepharidomycetes to be monophyletic and nested within Chytridiomycota. Hyphal Monoblepharidomycetes formed a clade sister to the genera without hyphae, Harpochytrium and Oedogoniomyces. A likelihood ancestral state reconstruction indicated that hyphae arose independently within the Monoblepharidomycetes lineage and in at least two other lineages. Cytological differences among monoblepharidalean and other fungal hyphae are consistent with these convergent origins.

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Zoospore Ultrastructure of Monoblepharis polymorpha

Cited by 15 publications

References 0 publications

Taxonomic revision of the genus Zygorhizidium: Zygorhizidiales and Zygophlyctidales ord. nov. (Chytridiomycetes, Chytridiomycota)

Taxonomic revision of the genus Zygorhizidium: Zygorhizidiales and Zygophlyctidales ord. nov. (Chytridiomycetes, Chytridiomycota)

Molecular phylogenetics of the Chytridiomycota supports the utility of ultrastructural data in chytrid systematics

Cytology and molecular phylogenetics of Monoblepharidomycetes provide evidence for multiple independent origins of the hyphal habit in the Fungi

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