Olpidium | |
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Scientific classification | |
Kingdom: | |
Phylum: | |
Class: | incertae sedis |
Order: | incertae sedis |
Family: | |
Genus: | Olpidium |
Type species | |
Olpidium endogenum (A. Br.) Schroet. [1] | |
Synonyms [2] | |
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Olpidium is a fungal genus in the family Olpidiaceae. Members of Olpidium are zoosporic pathogens of plants, animals, fungi, and oomycetes. [3] [4]
Olpidium species exist as spherical zoosporangia inside the cells of their host. Zoospores emerge from a single discharge tube and have a single, posterior whiplash flagellum. Resting spores can be smooth or ornamented. [4]
Olpidium species infect a wide variety of plants, animals, protists, and fungi and are fairly common in aquatic and terrestrial ecosystems. Most of what is known about the genus comes from those species that infect higher plants, especially crops. [5] [6]
In higher plants, infection with Olpidium often causes little to no symptoms. An exception is Olpidium viciae , which causes broadbean blister. [6] However, Olpidium species can vector plant viruses. [5] For example, Olpidium brassicae transmits big-vein virus and big-vein associated varicosavirus among lettuce plants, and transmits tobacco mosaic virus among tobacco plants. Olpidium bornovanus or Olpidium cucurbitacearum serves as a vectors for a number of curcubit viruses. [6]
The genus Olpidium was placed in the Olpidiaceae in the Chytridiales. [3] Later some species, notably O. brassicae, were moved to the genus Pleotrachelus , but these were later moved back into the genus. [6] Based on zoospore ultrastructure, Donald J. S. Barr moved the genus into Spizellomycetales [7] In studies using molecular phylogenetics, O. brassicae, O. virulentus , and O. bornovanus were found to cluster with members of the former Zygomycota not with members of Chytridiomycota. One researcher, has elevated Olpidium to the level of phylum (Olpidiomycota) and split the genus into several genera. [6] While nomenclaturaly valid and accepted by some researchers, [8] others view these changes as controversial and unsupported. [6]
A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word flagellate also describes a particular construction characteristic of many prokaryotes and eukaryotes and their means of motion. The term presently does not imply any specific relationship or classification of the organisms that possess flagella. However, the term "flagellate" is included in other terms which are more formally characterized.
Chytridiomycota are a division of zoosporic organisms in the kingdom Fungi, informally known as chytrids. The name is derived from the Ancient Greek χυτρίδιον (khutrídion), meaning "little pot", describing the structure containing unreleased zoospores. Chytrids are one of the early diverging fungal lineages, and their membership in kingdom Fungi is demonstrated with chitin cell walls, a posterior whiplash flagellum, absorptive nutrition, use of glycogen as an energy storage compound, and synthesis of lysine by the α-amino adipic acid (AAA) pathway.
Tombusviridae is a family of single-stranded positive sense RNA plant viruses. There are three subfamilies, 17 genera, and 95 species in this family. The name is derived from Tomato bushy stunt virus (TBSV).
Lettuce big-vein disease causes leaf distortion and ruffling in affected lettuce plants.
Tomato bushy stunt virus (TBSV) is a virus of the tombusvirus family. It was first reported in tomatoes in 1935 and primarily affects vegetable crops, though it is not generally considered an economically significant plant pathogen. Depending upon the host, TBSV causes stunting of growth, leaf mottling, and deformed or absent fruit. The virus is likely to be soil-borne in the natural setting, but can also transmitted mechanically, for example through contaminated cutting tools. TBSV has been used as a model system in virology research on the life cycle of plant viruses, particularly in experimental infections of the model host plant Nicotiana benthamiana.
Mycoviruses, also known as mycophages, are viruses that infect fungi. The majority of mycoviruses have double-stranded RNA (dsRNA) genomes and isometric particles, but approximately 30% have positive-sense, single-stranded RNA (+ssRNA) genomes.
Olpidium brassicae is a plant pathogen, it is a fungal obligate parasite. In 1983, the Alsike, Alberta area's clover was struck by a fungus epidemic of Olpidium brassicae, previously not seen in Canada.
Rhizophydiales are an important group of chytrid fungi. They are found in soil as well as marine and fresh water habitats where they function as parasites and decomposers.
Spizellomycetales is an order of fungi in the Chytridiomycetes. Spizellomycetalean chytrids are essentially ubiquitous zoospore-producing fungi found in soils where they decompose pollen. Recently they have also been found in dung and harsh alpine environments, greatly expanding the range of habitats where one can expect to find these fungi.
Blastocladiomycota is one of the currently recognized phyla within the kingdom Fungi. Blastocladiomycota was originally the order Blastocladiales within the phylum Chytridiomycota until molecular and zoospore ultrastructural characters were used to demonstrate it was not monophyletic with Chytridiomycota. The order was first erected by Petersen for a single genus, Blastocladia, which was originally considered a member of the oomycetes. Accordingly, members of Blastocladiomycota are often referred to colloquially as "chytrids." However, some feel "chytrid" should refer only to members of Chytridiomycota. Thus, members of Blastocladiomyota are commonly called "blastoclads" by mycologists. Alternatively, members of Blastocladiomycota, Chytridiomycota, and Neocallimastigomycota lumped together as the zoosporic true fungi. Blastocladiomycota contains 5 families and approximately 12 genera. This early diverging branch of kingdom Fungi is the first to exhibit alternation of generations. As well, two (once) popular model organisms—Allomyces macrogynus and Blastocladiella emersonii—belong to this phylum.
Tobacco necrosis virus A is a plant pathogenic virus of the family Tombusviridae.
In epidemiology, a disease vector is any living agent that carries and transmits an infectious pathogen to another living organism; agents regarded as vectors are organisms, such as parasites or microbes. The first major discovery of a disease vector came from Ronald Ross in 1897, who discovered the malaria pathogen when he dissected a mosquito.
Rozella is a fungal genus of obligate endoparasites of a variety of hosts, including Oomycota, Chytridiomycota, and Blastocladiomycota. Rozella was circumscribed by French mycologist Marie Maxime Cornu in 1872. Considered one of the earliest diverging lineages of fungi, the widespread genus contains 27 species, with the most well studied being Rozella allomycis. Rozella is a member of a large clade of fungi referred to as the Cryptomycota/Rozellomycota. While some can be maintained in dual culture with the host, most have not been cultured, but they have been detected, using molecular techniques, in soil samples, and in freshwater and marine ecosystems. Zoospores have been observed, along with cysts, and the cells of some species are attached to diatoms.
Marine fungi are species of fungi that live in marine or estuarine environments. They are not a taxonomic group, but share a common habitat. Obligate marine fungi grow exclusively in the marine habitat while wholly or sporadically submerged in sea water. Facultative marine fungi normally occupy terrestrial or freshwater habitats, but are capable of living or even sporulating in a marine habitat. About 444 species of marine fungi have been described, including seven genera and ten species of basidiomycetes, and 177 genera and 360 species of ascomycetes. The remainder of the marine fungi are chytrids and mitosporic or asexual fungi. Many species of marine fungi are known only from spores and it is likely a large number of species have yet to be discovered. In fact, it is thought that less than 1% of all marine fungal species have been described, due to difficulty in targeting marine fungal DNA and difficulties that arise in attempting to grow cultures of marine fungi. It is impracticable to culture many of these fungi, but their nature can be investigated by examining seawater samples and undertaking rDNA analysis of the fungal material found.
Plasmodiophora bicaudata is a marine pathogen, an obligate parasite of seagrass of the genus Zostera and the causal agent of wasting disease in the genus. These marine plants grow in fine sediment in shallow seas and the pathogen seems to have a worldwide distribution.
Synchytrium is a large genus of plant pathogens within the phylum Chytridiomycota. Species are commonly known as false rust or wart disease. Approximately 200 species are described, and all are obligate parasites of angiosperms, ferns, or mosses. Early species were mistakenly classified among the higher fungi because of their superficial similarity to the rust fungi. Anton de Bary and Mikhail S. Woronin recognized the true nature of these fungi and established the genus to accommodate Synchytrium taraxaci, which grows on dandelions, and S. succisae, which grows on Succisa pratensis. Synchytrium taraxaci is the type of the genus. The genus has been divided into 6 subgenera based on differences in life cycles.
Olpidiaceae is a fungal plant pathogen families that was placed in the order Chytridiales.
Physoderma is a genus of chytrid fungi. Described by German botanist Karl Friedrich Wilhelm Wallroth in 1833, the genus contains some species that are parasitic on vascular plants, including P. alfalfae and P. maydis, causative agents of crown wart of alfalfa and brown spot of corn, respectively. Of the chytrid genera, Physoderma is the oldest. However, species were confused with the rust fungi, the genus Synchytrium, and the genus Protomyces of Ascomycota. Members of Physoderma are obligate parasites of pteridophytes and angiosperms. There are approximately 80 species within this genus.
Chytriomyces is the type genus of fungi in the family Chytriomycetaceae. The genus was described by mycologist John Sidney Karling in 1945. The family, created by Peter Letcher in 2011, contains species with a Group I-type zoospore, distinguishing it from Chytridiaceae members, which have a Group II-type zoospore.
Dendrochytridium is a fungal genus in the order Chytridiales. The genus is monotypic, containing the single saprobic species Dendrochytridium crassum, isolated from detritus collected from an Australian tree canopy. Both the genus and species were described as new to science in 2013. Phylogenetically, Dendrochytridium crassum groups together in a clade with other fungi possessing Group II-type zoospores. These fungi, which include representatives from the genera Chytridium, Phlyctochytrium, Chytriomyces, and Polyphlyctis are classified in the family Chytridiaceae.