DIFFERENTIATION OF GAEUMANNOMYCES-GRAMINIS FROM OTHER TURF-GRASS FUNGI BY AMPLIFICATION WITH PRIMERS FROM RIBOSOMAL INTERNAL TRANSCRIBED SPACERS

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