''Olpidium'' is a

fungal A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as one of the tradit ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

in the family Olpidiaceae. Members of ''Olpidium'' are

zoosporic A zoospore is a motile asexual spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of tim ...

pathogen In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...

s of

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

animal Animals are multicellular, eukaryotic organisms in the Biology, biological Kingdom (biology), kingdom Animalia (). With few exceptions, animals heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, ...

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

, and

oomycete The Oomycetes (), or Oomycota, form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms within the Stramenopiles. They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction o ...

Morphology

''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 A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...

. Resting spores can be smooth or ornamented.

Ecology

''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. In higher plants, infection with ''Olpidium'' often causes little to no symptoms. An exception is '' Olpidium viciae'', which causes

broadbean ''Vicia faba'', commonly known as the broad bean, fava bean, or faba bean, is a species of vetch, a flowering plant in the pea and bean family Fabaceae. It is widely cultivated as a crop for human consumption, and also as a cover crop. Varieti ...

blister. However, ''Olpidium'' species can vector

plant virus Plant viruses are viruses that have the potential to affect plants. Like all other viruses, plant viruses are obligate intracellular parasites that do not have the molecular machinery to replicate without a host. Plant viruses can be pathoge ...

es. For example, ''

Olpidium brassicae ''Olpidium brassicae'' is a plant pathogen, it is a fungal obligate parasite. In 1983, the Alsike, Alberta area's clover (which is a major part of horses' diet) was struck by a fungus epidemic of ''Olpidium brassicae'', previously not seen in Ca ...

'' transmits big-vein virus and big-vein associated

varicosavirus ''Varicosavirus'' is a genus of plant viruses. The virus is associated with swelling in plant vein tissues. They are negative single stranded RNA viruses. The genus contains 43 species. Structure Virions consist of a non-enveloped rod-shaped ca ...

among lettuce plants, and transmits

tobacco mosaic virus Tobacco mosaic virus (TMV) is a positive-sense single-stranded RNA virus species in the genus '' Tobamovirus'' that infects a wide range of plants, especially tobacco and other members of the family Solanaceae. The infection causes characteris ...

among tobacco plants. ''

Olpidium bornovanus ''Olpidium'' is a fungi, fungal genus in the family Olpidiaceae. Members of ''Olpidium'' are zoospore, zoosporic pathogens of plants, animals, fungi, and oomycetes. Morphology ''Olpidium'' species exist as spherical zoosporangia inside the cell ...

'' or ''

Olpidium cucurbitacearum ''Olpidium'' is a fungal genus in the family Olpidiaceae. Members of ''Olpidium'' are zoosporic pathogens of plants, animals, fungi, and oomycetes. Morphology ''Olpidium'' species exist as spherical zoosporangia inside the cells of their host. ...

'' serves as a vectors for a number of curcubit viruses.

Taxonomy

The genus ''Olpidium'' was placed in the Olpidiaceae in the

Chytridiales Fungi of the order Chytridiales, like other members of its division, may either have a monocentric thallus or a polycentric rhizomycelium. When the ribosomal genes of members classified in this order were first examined using molecular techniq ...

. Later some species, notably ''O. brassicae'', were moved to the genus '' Pleotrachelus'', but these were later moved back into the genus. Based on zoospore ultrastructure, Donald J. S. Barr moved the genus into Spizellomycetales In studies using molecular

phylogenetics In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

, ''O. brassicae'', '' O. virulentus'', and ''O. bornovanus'' were found to cluster with members of the former

Zygomycota Zygomycota, or zygote fungi, is a former phylum, division or phylum of the kingdom Fungi. The members are now part of two Phylum, phyla: the Mucoromycota and Zoopagomycotina, Zoopagomycota. Approximately 1060 species are known. They are mostly t ...

not with members of

Chytridiomycota Chytridiomycota are a division of zoosporic organisms in the kingdom Fungi, informally known as chytrids. The name is derived from the Ancient Greek ('), meaning "little pot", describing the structure containing unreleased zoospores. Chytrid ...

. One researcher, has elevated ''Olpidium'' to the level of phylum (

Olpidiomycota Olpidiaceae is a fungal plant pathogen family of genera that was placed in the order Olpidiales. Taxonomy Based on the work of Philippe Silar and "The Mycota: A Comprehensive Treatise on Fungi as Experimental Systems for Basic and Applied Resear ...

) and split the genus into several genera. While nomenclaturaly valid and accepted by some researchers, others view these changes as controversial and unsupported.

References

External links

Index Fungorum
Chytridiomycota genera {{Chytridiomycota-stub