Overview
Pleurotus is a genus of gilled mushrooms with species known as oyster, abalone, or tree mushrooms. It includes some of the most commonly cultivated edible mushrooms in the world, such as P. ostreatus. Additionally, some species have been used in the mycoremediation of pollutants.
Description
The caps may be laterally attached (with no stipe). If there is a stipe, it is normally eccentric and the gills are decurrent along it. The term pleurotoid is used for any mushroom with this general shape.
Taxonomy
The classification of species within the genus Pleurotus is difficult due to high phenotypic variability across wide geographic ranges, geographic overlap of species, and ongoing evolution and speciation. Early taxonomic efforts placed the oyster mushrooms within a very broad Agaricus as Agaricus ostreatus (Jacq. 1774). Paul Kummer defined the genus Pleurotus in 1871; since then, the genus has been narrowed with some species reclassified to other genera, such as Favolaschia, Hohenbuehelia, Lentinus, Marasmiellus, Omphalotus, Panellus, Pleurocybella, and Resupinatus. See Singer (1986) for an example of Pleurotus taxonomy based on morphological characteristics.
Phylogeny
More recently, molecular phylogenetics has been utilized to determine genetic and evolutionary relationships between groups within the genus, delineating discrete clades. Pleurotus, along with the closely related genus Hohenbuehelia, has been shown to be monophyletic. Tests of cross-breeding viability between groups have been used to further define which groups are deserving of species rank, as opposed to subspecies, variety, or synonymy. If two groups of morphologically distinct Pleurotus fungi are able to cross-breed and produce fertile offspring, they meet one definition of species. These reproductively discrete groups, referred to as intersterility groups, have begun to be defined in Pleurotus. Many binomial names used in literature are now being grouped together as species complexes using this technique, and may change.
Phylogenetic species
The following species list is organized according to 1. phylogenetic clade, 2. intersterility group (group number in Roman numerals) or sub-clade, and then 3. any older binomial names that have been found to be closely related, reproductively compatible, or synonymous, although they may no longer be taxonomically valid. This list is likely to be incomplete. , USA , Philippines * P. ostreatus clade ** I. P. ostreatus (oyster or pearl oyster mushroom) – North America and northern Eurasia *** P. florida ** II. P. pulmonarius (phoenix or Indian oyster mushroom) – North America, Eurasia, and Australasia *** P. columbinus *** P. sapidus ** III. P. populinus – North America ** VI. P. eryngii (king oyster mushroom) – Europe and the Middle East *** P. ferulae *** P. fossulatus – Afghanistan *** P. nebrodensis ** XII. P. abieticola – Asia ** XIII.
P. albidus – Caribbean, Central America, South America *P. djamor-cornucopiae clade ** IV. P. cornucopiae (branched oyster mushroom) – Europe *** P. citrinopileatus (golden oyster mushroom) – eastern Asia *** P. euosmus (tarragon oyster mushroom) ** V. P. djamor (pink oyster mushroom) – pantropical *** P. flabellatus *** P. salmoneo-stramineus *** P. salmonicolor ** XI. P. opuntiae – North America, New Zealand ** XVI. P. calyptratus * P. cystidiosus clade ** VII. P. cystidiosus (abalone mushroom) – global *** P. abalonus – Taiwan *** P. fuscosquamulosus – Africa, Europe *** P. smithii – Mexico ** IX. P. dryinus – North America, Europe, and New Zealand * VIII. Lentinus levis – subtropical to tropical, moved to genus Lentinus. * X. P. tuber-regium (king tuber mushroom) – Africa, Asia, Australasia * XIV. P. australis (brown oyster mushroom) – Australia and New Zealand * XV.
P. purpureo-olivaceus – Australia and New Zealand ** P. rattenburyi
Incertae sedis species
* P. parsonsii * P. velatus
Former species
* P. gardneri was reclassified to the genus Neonothopanus in 2011. * P. levis was reclassified to the genus Lentinus. * P. sajor-caju was reclassified to the genus Lentinus. * P. nidiformis was reclassified to the genus Omphalotus in 1994.
Etymology
The genus name Pleurotus refers to the mushroom caps being laterally attached to the substrate. It is derived of the Ancient Greek word : pleurón rib, side.
Ecology
Pleurotus fungi are found in both tropical and temperate climates throughout the world. Most species of Pleurotus are white-rot fungi on hardwood trees, although some also decay conifer wood. Pleurotus eryngii is unusual in being a weak parasite of herbaceous plants, and P. tuber-regium produces underground sclerotia. In addition to being saprotrophic, all species of Pleurotus are also nematophagous, catching nematodes by paralyzing them with a toxin. In the case of the carnivorous mushroom Pleurotus ostreatus, it was shown that small, fragile lollipop-shaped structures (toxocysts) on fungal hyphae contain a volatile ketone, 3-octanone, which disrupts the cell membrane integrity of nematodes, leading to rapid cell and organismal death, hypothetically either to defend themselves and/or to acquire nutrients.
Culinary
Oyster mushrooms are some of the most commonly cultivated edible mushrooms. They are often used in vegetarian cuisine. The crew of the Fram2 orbital mission are planning to grow oyster mushrooms in space for the first time. The code name for this experiment is Mission MushVroom, and is led by FOODiQ Global, an Australian company. If successful, these mushrooms could provide a sustainable food source during lengthy space missions.
Bioremediation
Pleurotus fungi have been used in the mycoremediation of pollutants, such as petroleum and polycyclic aromatic hydrocarbons. After the 2017 Tubbs Fire in California, oyster mushrooms were grown to help remediate toxic ash run-off.
See also
* Antromycopsis – an anamorphic form of Pleurotus * List of Pleurotus species
External links
* Pleurotus Genus on the Mushroom, the Journal of Wild Mushrooming site * Oysters: Pleurotoid Mushrooms at MushroomExpert.com *