NTRASPECIFIC GENETIC DIVERSITY OF Phytophthora cryptogea AND P. drechsleri

Phytophthora drechsleri and P. cryptogeaare phylogenetically closely related oomyceteous plant pathogens. In order to evaluate genetic variation among these species, isolates of P. drechsleri and P. cryptogeafrom various hosts and localities. Also some isolates of another close taxon, P. erythroseptica,were characterized by the random amplified microsatellites (RAMS) technique using three degenerated anchored primer: VHV(GT)₇G, DDB(CCA)_­5 and DHB(CGA)₅. Two different banding patterns were observed among isolates consisting of 26 RAMS markers among P. cryptogea and P. erythroseptica isolates and 18 among P. drechsleri isolates. UPGMA-analysis of RAMS markers showed that P. cryptogea has considerable molecular variability and illustrates intraspecific variations. There are at least three distinct genetic groups within P. cryptogea populations worldwide with average similarity of 54-60% between groups. P. erythroseptica isolates produced almost the same RAMS polymorphic markers as P. cryptogea and interspersed as a divergent lineage of P. cryptogea in the P. cryptogea UPGMA dendrogram. It seems that P. erythroseptica isolates are much similar to two of the P. cryptogea groups than the third group to the others. There was no evidence for biogeographically structured lineages which could be as a consequence of wide host range and transglobal transposition of lineages associated with worldwide movement of agricultural and horticultural plants. Data showed that P. drechsleriis a more homogenous species but there are some lineages that seem to reflect the geographic distribution. The RAMS analysis did not reveal any trends for host specificity between different lineages of these two species.