MOLECULAR CHARACTERIZATION OF PHYTOPHTHORA ISOLATES WITH NONPAPILLATE SPORANGIA CAUSING ROOT-ROT OF RASPBERRY USING MTDNA RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISMS

The main focus of this study was a group of Phytophthora isolates with nonpapillate sporangia, pathogenic on raspberry, that have been assigned either to P. erythroseptica, atypical P. megasperma, or P. fragariae by different authors. A numerical analysis of their mitochondrial DNA (mtDNA) restriction fragment length polymorphisms revealed that these problematic isolates did not show a close genetic relationship to isolates of either P. erythroseptica or P. megasperma. However, mtDNA banding patterns did exhibit a 54-55 % similarity with P. fragariae isolates from strawberry, indicating that these raspberry isolates might possibly share a common ancestor with species. Additional P. megasperma isolates from raspberry, previously characterized as P. Megasperma var. megasperma (Duncan, Kennedy & Seemuller, 1987) and belonging to the 'BHR' subgroup of P. megasperma (Hansen et al., 1986), were placed into two discrete molecular groups.