One of the most important rice pathogens is Fusarium moniliforme (perfect stage: Gibberella fujikuroi), the causal agent of the super-elongation ("bakanae") disease. Thirty-seven strains of this species from different geographical regions were analyzed for their ability to produce gibberellins (GA) and for genetic relatedness by random amplified polymorphic DNA (RAPD). All GA-producing isolates showed nearly identical RAPD patterns using 51 oligonucleotide nona- and deca-mers as arbitrary primers. On the other hand, large differences between GA-nonproducing isolates were obtained. Comparison of the RAPD patterns with those of the tester strains of the six known mating populations (A, B, C, D, E, F) of G. fujikuroi showed that all producer strains belong to mating population C and all nonproducer isolates to other mating populations. Evidence for the usefulness of the RAPD technique to distinguish between mating populations was provided by sexual crossings. Consensus phylogenetic trees based on RAPDs were constructed by the Phylogenetic Analysis Using Parsimony (PAUP) system. In combination with morphological analysis, RAPD can distinguish between different species of the genus Fusarium. These investigations may find an application in the diagnosis of unknown Fusarium spp. and in distinguishing isolates of G. fujikuroi within the section Liseola.

Oilseed rape (Brassica napus) is attacked by many parasitic fungi which often occur in mixed infections. Monitoring of these phytopathogens by morphological criteria is restricted due to their appearance especially in the later stages of disease development.We have developed molecular markers for a clear-cut differentiation of a variety of rape seed pathogenic fungi based on randomly amplified polymorphic DNA (RAPD), Twenty polymorphic fragments have been selected in Southern hybridization experiments to test their taxon-specificity. In summary, only four amplification products gave unspecific cross-hybridization patterns, one fragment corresponds to a genetic element common to three species within the gtnus Allernaria, and 15 RAPD markers were highly specific for distinct fungal species. This report demonstrates the value of the RAPD-PCR technique to amplify taxon-specific DNA fragments that can be used as hybridization probes for the diagnosis of a variety of rape seed pathogens (Aiternaria hrassieae, A. brassieicola, A. raphant, Cylindrosporium concentrieum; Fusarium moniliforme; Phoma lingam; Pythium sp.; Rhizoetonia solani: Selerotinia sclerotiorum, Verticillium dahliae, V. latericium). Zusammenfassung Auf RAPD basierende molekulare Diagnose pilzlicher Mischinfektionen bei Raps (Brassica napus); Nachweis gattungs-und artenspeziiischer Sequenzen in den Genomen der PilzeRaps (Brassica napus) wird von zahlreichen parasitischen Pilzen befallen, wobei haufig Mischinfektionen auftreten, Bei der Feststellung des Befalls durch diese Phytopathogene sind morphologische Symptome von nur begrenztem Wert, denn sie erscheinen vor allem in den spateren Stadien der Krankheitsentwicklung, Auf der Grundlage der "random amplified polymorphic DNA" (RAPD) entwickeiten wir molekulare Marker zur eindeutigen Differenzierung verschiedener rapspathogener Pilze, In Southern-Hybridisierungs-Experimenten wtirden zwanzig polymorphe Fragmente selektiert und hinsichtlich ihrer Taxon-Spezifitat geprtift, Nur vier Amplifikationsprodukte ergaben linspezifische Kretizhybridisierungsmuster, Ein Fragment entspricht einem genetischen Element, das drei Alternaria-Arten eigen ist, und fiinfzehn RAPD-Marker waren hochspezifisch fur bestimmte Pilzarten, Dieser Bericht zeigt den Wert des RAPD-PCRVerfahrens zur Amplifizierung taxon-spezifischer DNAFragmente, die als Hybridisierungssonden ftir die Diagnose verschiedener Rapspathogene (Aiternaria brassicae, A. brassicicoia, A. raphanii, Cylindrosporium concenlricum, Fusarium moniliforme, Phoma lingam, Pythium sp,, Rhizoclonia solani, Selerotinia sclerotiorum, Verticillium dahliae, V. laterieium) eingesetzt werden konnen.

Polymerase chain reaction (PCR) primers, specific for the aggressive pathogenicity group of the rape seed pathogen Leptosphaeria maculans, were obtained according to the following experimental outline: DNA bands that differentiate between aggressive (A) and nonaggressive (NA) isolates were generated by the random amplified polymorphic DNA approach (RAPD). Differential RAPD bands were checked for pathogenicity group-specificity and sequenced by a combination of chemical and dideoxynucleotide chain termination methods. Based on the DNA sequence longer and highly specific primer pairs for conventional PCR under stringent conditions were designed, which were tested on 97 isolates of L, maculans belonging to different pathogenicity groups.

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