CHARACTERIZATION OF THE EUROPEAN PATHOGEN POPULATION OF MAGNAPORTHE-GRISEA BY DNA-FINGERPRINTING AND PATHOTYPE ANALYSIS

The genetic variability among 41 isolates of the blast pathogen (Magna porthe grisea) from five European rice growing countries was studied. The genealogy of the isolates was investigated by DNA fingerprinting a nd the results compared to the degree of similarity for (a)virulence f actors. Fingerprinting grouped the isolates into five discrete lineage s, that typically showed less than 65% band similarity. Within each li neage, two or more haplotypes were detected with a band similarity of 80% or higher. Each lineage showed a characteristic virulence pattern. All isolates of lineage 'E5' belonged to the same pathotype. The othe r lineages were composed of clusters of closely related pathotypes tha t showed variation for virulence to cultivars with certain known resis tance genes, while remaining invariably (a)virulent to others. In most cases, lineage classification of an isolate could be easily inferred by its pathotype. Certain resistance genes and certain lineage-excludi ng resistance gene combinations appear to provide protection against a ll of the virulence factors sampled.