Isozyme Variations of Six Evergreen Azalea Species Distributed in Kyushu, Japan

Abstract

Isozyme variations in six wild evergreen azalea species distributed in Kyushu were investigated and the effectiveness of the isozyme markers for distinguishing them was assessed. Five polymorphic loci in three enzyme systems, Gpi-2, Mdh-1, Mdh-2, Pgm-1 and Pgm-2 were surveyed. Rhododendron sataense had the widest isozyme variation among six azalea species. The allelic variation of R. kaempferi was relatively wide, whereas those of R. kiusianum, R. serpyllifolium, and R. eriocarpum were narrow. Rhododendron eriocarpum, belonging to Tsutsusi series, and R. serpyllifolium, belonging to Serpyllifolia series, were easily distinguished in Gpi-2 from other azalea species belonging to Kaempferia series ; the species belonging to Kaempferia series could not be distinguished from each other in any enzyme systems used in this study. Although we thought that the origin of flower color variation in R. sataense was the result from the natural crossings between R. kaempferi and R. eriocarpum, it appears that R. eriocarpum has little or no role in the flower color variation of R. sataense based on the results of our isozyme analysis.