Separation by Protein Electrophoresis of Six Species ofPhytophthoraAssociated with Deciduous Fruit Crops

Abstract

Polyacrylamide gel electrophoresis was employed to compare the patterns of native and sodium dodecyl sulfate dissociated proteins obtained from mycelia of six species of Phytophthora isolated primarily from deciduous fruit crops grown in the Great Lakes states. The intraspecific variation in banding patterns among isolates identified as P. cactorum, P. cambivora, and P. syringae was less than that among isolates identified as P. megasperma, P. cryptogea, and P. drechsleri. When native proteins were analyzed, the number of distinct subgroups distinguished were two in P. cactorum, two in P. syringae, one in P. cambivora, two in P. drechsleri, three in P. cryptogea, and six in P. megasperma. When dissociated proteins were analyzed, P. cactorum, P. syringae, and P. cambivora each formed single, distinct groups: P. cryptogea and P. drechsleri each formed two subgroups, one of which was common to isolates of both species. Most isolates of P. megasperma from deciduous fruit crops, when compared with isolates representing the six protein subgroups previously established for isolates P. megasperma, had protein patterns belonging to the "broad host range" group, whereas the remaining few belonged to the "apple, cherry, apricot" group. The results obtained with electrophoresis support the use of this approach as an aid in distinguishing the species and subgroups within species of Phytophthora encountered on deciduous fruit crops.