DNA FINGERPRINTING FOR DIFFERENTIATING AGGRESSIVENESS GROUPS OF THE RAPE SEED PATHOGEN LEPTOSPHAERIA-MACULANS

Genomic DNA was prepared from a total of 16 different isolates of the rape seed pathogen Leptosphaeria maculans, the teleomorph of Phoma lingam. These DNA preparations were digested with the restriction endonucleases BamH I, EcoR I, Hpa II, Mbo I, Msp I and Sau3A I, separated on agarose gels and analysed by hybridization with the radioactively labelled synthetic oligonucleotides (GTG)5, (GACA)4 or (CT)8 or with labelled DNA of phage M13. These probes reveal a high degree of DNA polymorphism within the species. Although all investigated isolates can dearly and unequivocally be distinguished from each other, aggressive and non-aggressive strains appear as consistent groups with high degrees of similarity. The fingerprinting technique is thus an appropriate tool for molecular diagnosis of this important plant pathogen. In general, oligonucleotide fingerprinting may be regarded as a convenient technique to identify individual fungal strains with a reliability similar to that of mammalian systems.