Pyrenomycetes


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Pyrenomycetes

[pī‚rē·nō·mī′sēd‚ēz]
(mycology)
The largest class in the subdivision Ascomycotina, distinguished by a single-walled ascus and the coiled branches that form on the hyphae to initiate ascocarp formation. Also known as perithecial ascomycetes.

Pyrenomycetes

 

a group of ascomycetous fungi whose fruiting bodies—perithecia—open at the apex by a pore or crack. There are about 640 genera, embracing 6,000 species (according to other data, up to 10,000 species). The fruiting bodies are formed either directly on the hyphae of the mycelium or inside a special mass of hyphae—the stroma. Sporebearing is ascous or, in many species, conidial (as in imperfect fungi). Many species in the conidial stage parasitize higher plants; after the plant dies, they develop as saprophytes and by spring form asci. Thus the fungus is able to exist under the most diverse ecological conditions.

The majority of Pyrenomycetes are saprophytes and live predominantly on plant substrates. Together with other microorganisms, they play a role in the cycle of matter. Parasitic species are extremely destructive. For example, Claviceps purpurea, whose sclerotia contain alkaloids, are toxic to man and lower animals (ergotism). Epichloë typhina is the causative agent of cattail disease, a fungus infection of grasses. Some species of Nectria, Eutypa, Nummularia, Diatrype, and Valsa cause cancer and necrosis of trees and shrubs. Species of the order Coryneliales are the causative agents of many tropical plant diseases. Ceratocystis ulmi, or Ceratostomella ulmi, causes the dessication of Ulmaceae, Calonectria graminicola causes snow mold of winter plantings, and species of Phyllachora produce leaf spot in cereals. Species of Cordyceps parasitize insect larvae and fungi, and species of Nitschkia live on some fungi. The fungi Neurospora crassa and N. sitophila, widely used in biochemical and genetic research, belong to Pyrenomycetes. Many species of Pyrenomycetes are mycobionts of lichens.

V. A. MEI’NIK

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Algunas especies de Xylaria (Pyrenomycetes, Sphaeriales) habitantes en hojarasca de bosques mexicanos.
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Key words: Tagosodes orizicolus, yeast-like symbiotes, 18S rDNA, genetic relationships, Pyrenomycetes, rice planthoppers.
These were classified among the Pyrenomycetes in the subphylum Ascomycota.
The position of YLSTo within the phylum Ascomycota was determined after aligning the complete sequence of the NS1-6 (1438 nt) clone with that of eleven ascomycete fungi: Arcoesphaera apis, Aspergyillus fumigatus, Coccidioides immitis (Class Plectomycetes); Hypomyces chrysospermus, Ophiostoma ulmi, Podospora anserina (Class Pyrenomycetes); Lecanora dispersa, Spathularia flavida, Spaenophorus globosus (Class Discomycetes); Candida albicans, Saccharomyces cerevisiae (Order Saccharomycetales) and Ustilago maydis (Class Basidiomycetes) as an outgroup (Fig.
The relationship between YLSTo with the Pyrenomycetes was determined by comparing the symbiote 1386 nt 18S rDNA segment with that from nine fungi of this class: H.
A revision of the classification of the Ascomycetes with special emphasis on the Pyrenomycetes. Mycologia 41: 99-127.
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Taxonomic Studies of Coprophilous Fungi of the Division Ascomycota (Class: Pyrenomycetes) from Zulia state, Venezuela
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Notas sobre la historia y relaciones de hospedante y distribucion del genero Xylaria (Pyrenomycetes, Sphaeriales) en Mexico.
Algunas especies dq Xylaria (Pyrenomycetes, Sphaeriales) habitantes en hojarasca de bosques mexicanos.