Pyrenophora graminea

Pyrenophora graminea
Scientific classification
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. Barley stripe is disease of barley that once caused significant crop yield losses in many areas of the world.^[1]

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.

Sources

• Index Fungorum
• USDA ARS Fungal Database

External links

Research articles

• Tekauz, A. (1983). "Reaction of Canadian barley cultivars to Pyrenophora graminea, in the incitant of leaf stripe". CJPP 5: 294–301. http://www.cps-scp.ca/download/cjpp-archive/Vol5/CJPP5(4)294-301(1983).pdf. 
• Tekauz, A. (1990). "Determination of barley cultivar reaction to Pyrenophora graminea using disease nurseries". CJPP 12: 57–62. http://www.cps-scp.ca/download/cjpp-archive/Vol12/CJPP12(1)57-62(1990).pdf. 
• Tekauz, A.; A.W. Chiko (1980). "Leaf stripe of barley caused by Pyrenophora graminea: Occurrence in Canada and comparisons with barley stripe mosaic". CJPP 2: 152–158. http://www.cps-scp.ca/download/cjpp-archive/Vol2/CJPP2(3)152-158(1980).pdf. 
• Tekauz, A.; F.R. Harper, J.G.N. Davidson (1985). "Effect of date of seeding and seed treatment fungicides on infection of barley by Pyrenophora graminea". CJPP 7: 408–416. http://www.cps-scp.ca/download/cjpp-archive/Vol7/CJPP7(4)408-416(1985).pdf. 

References

1. ^ ^{a b} Mathre, D.E. (1997). Compendium of barley diseases. American Phytopathological Society. pp. 120 pp.