Differentiation of Gaeumannomyces graminis from other turf‐grass fungi by amplification with primers from ribosomal internal transcribed spacers

Abstract

A region comprising the 5.8S RNA gene and internal transcribed spacers 1 and 2 of the take‐all patch fungus, Gaeumannomyces graminis var. avenae, was cloned and sequenced using primers from the flanking 17S and 26S ribosomal RNA genes. The sequenced region showed 99% similarity between the two G. graminis isolates, and 70–80% similarity between these two isolates and several other species of fungi. From the sequence, oligonucleotide primers were selected which permitted specific amplification of DNA from G. graminis vars. avenae and graminis using the polymerase chain reaction (PCR). The assay could detect DNA of G. graminis strains obtained from a wide variety of hosts, but did not amplify DNA from many other fungi, including the important turf‐grass root pathogens Magnaporthe poae and Leptosphaeria korrae. The primers also did not amplify DNA from G. graminis var. tritici, M. rhizophila or Phialophora graminicola. The PCR‐based assay shows promise as a diagnostic tool for the take‐all pathogen in turf‐grass pathology.