PEROXIDASE POLYMORPHISM IN CITRUS

The enzyme peroxidase (E.C. 1.11.1.7) was found to exist in multiple molecular forms in the 30 taxa of Citrus [C. medica, C. limon, C. grandis, C. paradisi, C. aurantium, C. sinensis, C. reticulata, C. tachibana, C. macroptera, C. latipes, C. hystrix] and 3 related genera [Fortunella margarita, F. obovata, Poncirus trifoliata, Microcitrus virgata] studied. Some isoenzymes were common to most taxa, others were specific to certain taxa. Both qualitative and quantitative differences were found between and within taxa. There were also quantitative differences among individual isoenzymes in the profile of a given taxon. Certain isoenzymes, especially anodic ones, consistently showed weak activity and were poorly defined. The significance of peroxidase polymorphism in Citrus is discussed in terms of genetic and taxonomic applications, and limitations are noted.