ANALYSIS OF GENETIC DIVERSITY IN THE CRAYFISH PLAGUE FUNGUS, APHANOMYCES-ASTACI, BY RANDOM AMPLIFICATION OF POLYMORPHIC DNA

Arbitrary primers and the DNA polymerase chain reaction (PCR) techniqu e were applied to study genetic variation between different strains of the crayfish plague fungus, Aphanomyces astaci. Eight different prime rs among 15 tested were chosen for a comparative analysis of the diffe rent A. astaci strains. On average, each primer gave rise to 5-8 bands and a majority of the bands was polymorphic for at least some strains . Two main groups among the different Swedish isolates were clearly di scernible. One group included isolates from the indigenous crayfish sp ecies Astacus astacus and one isolate from As. leptodactylus originati ng from Turkey. The other main group included fungal isolates from bot h As. astacus and the introduced North American crayfish Pacifastacus leniusculus. In this latter case it seems likely that the introduced A merican signal crayfish has served as a vector and transmitted the pat hogen to the indigenous crayfish.