''Olpidium'' is a

fungal A fungus ( : fungi 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 a kingdom, separately from th ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

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

pathogen In biology, a pathogen ( el, πάθος, "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 ...

s of

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclu ...

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

fungi A fungus ( : fungi 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 a kingdom, separately from ...

, and

oomycete Oomycota forms a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms, called oomycetes (). They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction of an oospore is the resul ...

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 (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have f ...

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

plant virus Plant viruses are viruses that 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 pathogenic to higher plants. ...

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 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 characteri ...

among tobacco plants. '' Olpidium bornovanus'' or '' Olpidium cucurbitacearum'' 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 Division or divider may refer to: Mathematics *Division (mathematics), the inverse of multiplication *Division algorithm, a method for computing the result of mathematical di ...

. 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 Spizellomycetales is an order of fungi in the Chytridiomycetes Chytridiomycetes () is a class of fungi. Members are found in soil, fresh water, and saline estuaries. They are first known from the Rhynie chert. It has recently been redefined ...

In studies using molecular

phylogenetics In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups ...

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

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