Blumeria graminis
Encyclopedia
Blumeria graminis is a fungus that causes powdery mildew
on grasses, including cereal
s (called barley powdery mildew or corn mildew). It is the only species in the genus Blumeria. It has also been called Erysiphe graminis and (by its anamorph) Oidium monilioides or Oidium tritici.
,
but the molecular
studies have placed it into a clade
of its own.
Blumeria differs from Erysiphe in its digitate haustoria and in details of the conidial wall.
Eight special forms or formae speciales (ff.spp.) of B. graminis have been distinguished, each of which is parasitic on a particular genus of grasses. Those that infect crop plants are B. graminis f.sp. tritici, which causes powdery mildew of wheat
and infects other grasses in the genera Triticum and Aegilops
, f.sp. hordei on barley
, f.sp. avenae on oats
and f.sp. secalis on rye
. Other formae speciales are pathogenic on wild grasses, including agropyri on grasses in the genera Agropyron
and Elymus
, bromi on Bromus
spp., poae on Poa
spp. and lolii on Lolium spp. (ryegrass).
can cover the plant surface almost completely, especially the upper sides of leaves. Ascocarp
is dark brown, globose with filamentous appendages, asci
oblong. Ascospore
s hyaline, ellipsoid, 20-30 x 10-13 µm in size. Anamorph produces on hyaline conidiophores catenate conidia of oblong to cylindrical shape, not including fibrosin bodies, 32-44 x 12-15 µm in size. Haustoria are palmate.
Powdery mildew
Powdery mildew is a fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of fungi in the order Erysiphales. It is one of the easier diseases to spot, as its symptoms are quite distinctive. Infected plants display white powdery spots on the...
on grasses, including cereal
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...
s (called barley powdery mildew or corn mildew). It is the only species in the genus Blumeria. It has also been called Erysiphe graminis and (by its anamorph) Oidium monilioides or Oidium tritici.
Systematics
Previously B. graminis was included within the genus ErysipheErysiphe
Erysiphe is a genus of fungi in the Erysiphaceae family. Many of the species in this genus are plant pathogens which cause powdery mildew....
,
but the molecular
Molecular phylogeny
Molecular phylogenetics is the analysis of hereditary molecular differences, mainly in DNA sequences, to gain information on an organism's evolutionary relationships. The result of a molecular phylogenetic analysis is expressed in a phylogenetic tree...
studies have placed it into a clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
of its own.
Blumeria differs from Erysiphe in its digitate haustoria and in details of the conidial wall.
Eight special forms or formae speciales (ff.spp.) of B. graminis have been distinguished, each of which is parasitic on a particular genus of grasses. Those that infect crop plants are B. graminis f.sp. tritici, which causes powdery mildew of wheat
Wheat
Wheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...
and infects other grasses in the genera Triticum and Aegilops
Aegilops
Aegilops is a genus of plants generally known as goatgrasses and belonging to the grass family, Poaceae. There are about 23 species and numerous sub species in the genus. Various members of the genus are classed as agricultural weeds. Growing through the winter, they resemble winter wheat...
, f.sp. hordei on barley
Barley
Barley is a major cereal grain, a member of the grass family. It serves as a major animal fodder, as a base malt for beer and certain distilled beverages, and as a component of various health foods...
, f.sp. avenae on oats
OATS
OATS - Open Source Assistive Technology Software - is a source code repository or "forge" for assistive technology software. It was launched in 2006 with the goal to provide a one-stop “shop” for end users, clinicians and open-source developers to promote and develop open source assistive...
and f.sp. secalis on rye
Rye
Rye is a grass grown extensively as a grain and as a forage crop. It is a member of the wheat tribe and is closely related to barley and wheat. Rye grain is used for flour, rye bread, rye beer, some whiskeys, some vodkas, and animal fodder...
. Other formae speciales are pathogenic on wild grasses, including agropyri on grasses in the genera Agropyron
Agropyron
Agropyron is a genus of grasses , native to Europe and Asia. Species in the genus are commonly referred to as crested-wheat grasses...
and Elymus
Elymus (genus)
Elymus is a genus of perennial grasses in the tribe which contains many of the main cereal grains. Plants of this genus are known generally as wildrye or wheatgrass...
, bromi on Bromus
Bromus
Bromus is a large genus of the grass family . Estimates in the scientific literature of the number of species have ranged from 100 to 400, but plant taxonomists currently recognize around 160–170 species...
spp., poae on Poa
Poa
Poa is a genus of about 500 species of grasses, native to the temperate regions of both hemispheres. Common names include meadow-grass , bluegrass , tussock , and speargrass. "Poa" is Greek for fodder...
spp. and lolii on Lolium spp. (ryegrass).
Morphology
The myceliumMycelium
thumb|right|Fungal myceliaMycelium is the vegetative part of a fungus, consisting of a mass of branching, thread-like hyphae. The mass of hyphae is sometimes called shiro, especially within the fairy ring fungi. Fungal colonies composed of mycelia are found in soil and on or within many other...
can cover the plant surface almost completely, especially the upper sides of leaves. Ascocarp
Ascocarp
An ascocarp, or ascoma , is the fruiting body of an ascomycete fungus. It consists of very tightly interwoven hyphae and may contain millions of asci, each of which typically contains eight ascospores...
is dark brown, globose with filamentous appendages, asci
Ascus
An ascus is the sexual spore-bearing cell produced in ascomycete fungi. On average, asci normally contain eight ascospores, produced by a meiotic cell division followed, in most species, by a mitotic cell division. However, asci in some genera or species can number one , two, four, or multiples...
oblong. Ascospore
Ascospore
An ascospore is a spore contained in an ascus or that was produced inside an ascus. This kind of spore is specific to fungi classified as ascomycetes ....
s hyaline, ellipsoid, 20-30 x 10-13 µm in size. Anamorph produces on hyaline conidiophores catenate conidia of oblong to cylindrical shape, not including fibrosin bodies, 32-44 x 12-15 µm in size. Haustoria are palmate.