PEROXIDASE ISOENZYME GENES IN THE IDENTIFICATION OF APPLE CULTIVARS AND MALUS SPECIES

The peroxidase genotypes of 188 apple cultivars, rootstocks and Malus species were recorded. Four loci, PRX-2, PRX-3, PRX-4 and PRX-7 were i nvolved including 15 alleles. Using this information a clear grouping of 83 cultivars, 46 rootstocks and 59 species was achieved through kno wledge of the genetic basic of banding patterns, which consequently en abled secondary and inconsistent bands to be recognised and disregarde d as relevant factors in identification. The possible selective advant age of the PRX-2e allele recognised in descendants of 'Jonathan' (PRX- 2ce) is discussed. Triploid cultivars showed three different PRX-2 all eles including 'Ashmead's Kernel' (PRX-2bce), providing further eviden ce of the triploid nature of this cultivar.