MECHANISMS OF GENETIC ISOLATION OF PHYTOPHTHORA-INFESTANS (MONT.) D BY. SPECIFIC PATHOGENIC FORMS IN SEXUAL AND ASEXUAL POPULATIONS

The paper concentrates on population level research of the mechanisms inhibiting horizontal and vertical gen transmission in Phytophthora in festans. Isolation machanisms of divergence evolution of tomato and po tato isolates can be vegetative Incompatibility, low fertility and als o undependent sources of overwintering. The greatest number of oospore s was observed in crosses of T1 x T1 races. Pairing of potato T0 with tomato T1 gave the widest barrage zone, a low number of oospores and h igh propotion of abortive oospores. These observations suggest the gen e transfer between tomato adapted (T1) and unadapted (T0) to be restri cted, promoting conservation of adaptive gene complexes.