EN
The genetic similarity of three species: Septoria tritici, Stagonospora nodorum and Stagonospora avenae f. sp. triticea - important pathogens in many cereal production areas worldwide was assessed by random amplified polymorphic DNA (RAPD) assay. In preliminary research DNA of 14, 9, and 7 monopyenidios- pore isolates of S. nodorum, S. tritici, and S. a. tritícea, respectively, were amplified by PCR with four primers. Afterwards the research was focused on three mono- pyenidiospore isolates from each species studied. The isolates of each species selected for the study varied in pathogenicity and were diverse geographically. PCR with the set of 14 selected primers resulted in 99 different bands, ranged from 180 to 2500 base pairs in length. Most primers in PCR (especially RAD11, RAD31, RAD32, RAD33) revealed uniform bands for isolates of S. a. tritícea, that allow to identify this species among the others. The cluster analysis using Unweighed Pair-Group Method with Averaging (UPGMA) revealed interspecies disagreement among the isolates ranging from 32 to 53%. The intraspecies disagreement ranges were 17-20%, 38-43%, 42-44% for S. avenae f. sp. triticea, S. nodorum and S. tritici, respectively. Cluster analysis classified isolates into three homogeneous clusters. Each cluster grouped isolates of one species according to their current taxonomie ranks based on spore size, colony morphology and host ranges. In addition, two of the clusters represented by isolates of S. nodorum and S. a. tritícea were distinctly separated at a lower linkage distance from the third one comprising isolates of S. tritici. A slight inconsistency found in grouping some isolates indicates that such groupings should be done with caution. The present study indicates that the PCR- RAPD assay is of a potential use in taxonomy of Stagonospora spp. and Septoria tritici as well as in molecular identification of casual disease agents.