Supriya Ghosh (Editor)

Tapesia yallundae

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Kingdom
  
Fungi

Order
  
Helotiales

Genus
  
Tapesia

Higher classification
  
Oculimacula

Phylum
  
Ascomycota

Family
  
Dermateaceae

Scientific name
  
Tapesia yallundae

Rank
  
Species

Similar
  
Oculimacula, Common wheat, Aegilops ventricosa, Ceratobasidium cornigerum, Rhynchosporium secalis

Tapesia yallundae is the causal agent for a variety of cereal and forage grass diseases. The anamorph o f T. yallundae is the W-type strain of Pseudocercosporella herpotrichoides. The R-type strain of Pseudocercosporella herpotrichoides is now known as Tapesia acuformis.

Contents

Morphology

Produces two types of mycelium - one vegetative, yellow-brown, linear, and branching, the other dark and stromalike. Condiophores are simple or sparingly branched. Conidia (1.5-3.5 x 37-70 μm) are hyaline, curved, and mostly five- to seven-celled. Sclerotia or sclerotialike stromatic mycelium, at first white to yellow-brown but later dark brown, may also be found on the lesions of infected plants.

Black apothecia, 0.2 to 0.5 mm of diameter, form at the base of host culms. Apothecium contain cylindric to fusoid asci, of 35 to 38 µm x 5.9 to 7.4 µm. Ascospores are hyaline, fusoid, 0-1 septate, with a rounded end and an average size of 8.9 µm (7.4 to 10.3) x 2.07 µm (1.95 to 2.34).

Growth media

Tapesia yallundae can be grown on a moist, sterile wheat and barley straw, oat kernels, and a variety of simple agar media, preferably supplemented with wheat extract. Sporulation in vitro tends to originate from loose sporodochai. Young colonies on potato-dextrose agar are gray, compact and mounded.

Molecular characterization

Polymerase chain reaction (PCR) combined with restriction enzyme digestion of an amplified ribosomal DNA fragment, are now used to characterize T. yallundae isolates. Novartis produces a polymerase chain reaction (PCR) diagnostic tool that provides cereal growers with an efficient means for checking the progression of eyespot disease in cereals. The tool reveals the presence and extent of disease before symptoms develop and can identify the different eyespot strains including the W-type (Tapesia yallundae') and R-type (Tapesia acuformis).

Host species

Aegilops cylindrica1,, Aegilops ovata1,, Aegilops sp.1,, Aegilops triuncialis1,, Agropyron cristatum1,, Agropyron dasystachyum1,, Agropyron inerme1,, Agropyron repens1,, Agropyron riparium1,, Agropyron sp.1,, Avena fatua1,, Avena sativa1,, Avena sp.1,, Balsamorhiza sp.1,, Bromus carinatus1,, Bromus inermis1,, Bromus japonicus1,, Bromus sterilis1,, Bromus tectorum1,, Delphinium sp1,., Festuca idahoensis1,, Hordeum distichon1,, Hordeum vulgare1,, Koeleria cristata1,, Lithospermum ruderale1,, Lomatium triternatum1,, Poa sandbergii1,, Poa secunda, Secale cereale, Sitanion hystrix1,, Trisetum aestivum1,, Triticum aestivum1,, Triticum dicoccum1,, Triticum durum1,, Triticum monococcum1,, Triticum sp.1,, Triticum spelta1,, Triticum vulgare1,

Main diseases

Eyespot of wheat; eyespot of barley; eyespot of rye.

References

Tapesia yallundae Wikipedia