RESTRICTION ANALYSIS OF INTERNAL TRANSCRIBED SPACERS AND THE SMALL-SUBUNIT GENE OF RIBOSOMAL DNA AMONG 4 GAEUMANNOMYCES SPECIES

The 18S rDNA and the region spanning the two internal transcribed spac ers (ITS), which includes the 5.8S rDNA, from 36 isolates of four spec ies of Gaeumannomyces (G. graminis, G. incrustans, G. cylindrosporous, and G. leptosporous) were amplified using the polymerase chain reacti on. The amplified products were subjected to restriction enzyme digest ion. The restriction patterns in the ITS regions separated both the sp ecies of Gaeumannomyces and the three varieties of G. graminis. Specif ic variation in restriction patterns of the ITS regions was observed w ithin the isolates of G. g. var. graminis. Physical maps of the restri ction sites in the ITS region were constructed. Variation among isolat es of G., g. var, tritici and G. g. var. avenae was minimal. The 3' en d and 5' end of the 18S rDNA are conserved among varieties of G. grami nis and isolates of G. incrustans. The middle region of the nuclear 18 S rDNA amplified with NS3/NS6 primers showed four different lengths, a nd based on these data the species and varieties of Gaeumannomyces wer e arranged into five different groups. Group 1 had a length of 1.6 Kb and included isolates of G. graminis var. tritici, G. graminis var. av enae, and G. graminis var. graminis isolate WF9463; group 2 (1.4 Kb) i ncluded G. graminis var. graminis isolates WF9238 and WF9469; group 3 (1.2 Kb) included isolates of G. incrustans and G. graminis var. grami nis isolates WF9236, WF9237, and WF9454; group 4 (1.0 Kb) included G. graminis var. graminis isolates WF9014, WF921, WF9452, WF9455, WF9457, WF9462, WF9470, and WF9471; and finally group 5 included G. cylindros porous and G. leptosporous with a 1.1 Kb length.