THE USE OF ISOENZYME POLYMORPHISMS AS AN AID FOR CULTIVAR IDENTIFICATION IN STRAWBERRY

The study was intended to uniquely classify 32 strawberry cultivars an d two breeders' selections, mostly of Northern European origin, using four polymorphic enzyme systems: phosphoglucoisomerase (PGI), phosphog lucomutase (PGM), esterase (EST) and leucine amino peptidase (LAP). Th ree of these (PGI, PGM and LAP) had been used previously for this purp ose by workers in North America. The techniques of both starch (SGE) a nd polyacrylamide gel electrophoresis (PAGE) were used. Consistent ban ding patterns were obtained for PGI, PGM and LAP while EST produced a large number of sharp bands but the patterns were inconsistent. The th ree stable enzymes only were thus used for cultivar characterisation. Banding patterns were divided phenotypically to produce three regions for PGI and two for PGM and LAP, Nine different banding categories wer e observed for PGI, 13 for PGM and 10 for LAP. In combination these th ree enzyme systems permitted 30 of the 34 clones examined to be unique ly characterised. Although much of the material is closely related, e. g. nine of the cultivars have Gorella as one parent, the technique off ers a high level of discrimination. In the two cases where it was not possible to separate cultivars no common ancestors for at least three generations exist. The procedure will assist greatly in cases of misid entification where a particular clone is known to be one of a small nu mber of alternatives. Also, the banding patterns could be used as an a dditional criterion for identification, alongside various morphologica l characteristics, when publishing cultivar descriptions.