Pyrenophora graminea

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Pyrenophora graminea

Kingdom:	Fungi
Phylum:	Ascomycota
Class:	Ascomycetes
Order:	Pleosporales
Family:	Pleosporaceae
Genus:	Pyrenophora
Species:	P. graminea

Binomial name

Pyrenophora graminea
S. Ito & Kurib. 1931

Synonyms

Brachysporium gracile var. gramineum (Rabenh.) Sacc.
Drechslera graminea (Rabenh. ex Schltdl.)
Drechslera teres subsp. graminea (Rabenh. ex Schltdl.)
Helminthosporium gramineum Rabenh. ex Schltdl
Napicladium hordei Rostr.
Pleospora graminea Died.
Pyrenophora teres subsp. graminea (S. Ito & Kurib.)
Pyrenophora graminea S. Ito & Kurib.

Pyrenophora graminea is the causal agent of barley stripe.

[edit] Identification

Asexual stage: Pycnidia are rarely observed in nature. They are 70-176 μm in diameter, globose to pear-shaped, and develop superficially or partly submerged. The wall is thin and fragile and is yellow to brown, with a short ostiole. Pycnidiospores are 1.4-3.2 x 1.0-1.6 μm, spherical or ellipsoidal, hyaline, and nonseptate.^[1]

Sexual stage: Perithecia are rare in nature, they occur in barley straw in the autumn. The perithecia are 576-728 x 442-572 μm. They are supeficial to partly submerged and are elongate, with rigid setae on the surface. Acsi are club-shaped or cylindrical, clearly bitunicate, and rounded at the apex, with a short stalk at the base. Ascospores are 43-61 x 16-28 μm, light yellow-brown, ellipsoidal, and rounded at both ends, with transverse septa and one, occasionally two, septum in the median cells but never in the terminal cells.

Conidia are borne laterally and terminally on conidiophores, which usually occur in clusters of three to five. The conidia are straight with rounded ends and measure 11-24 x 30-100 μm. They are subhyaline to yellow-brown and have up to seven transverse septa.

In culture, mycelium is gray to olivaceous and is often sterile. Conidia may be formed when infected barley pieces as placed on water agar and incubated under diurnal light conditions followed by a period of chilling.