Abstract: The acidic peroxidase isozymes in petals of 106 Citrus and Fortunella species and cultivars were studied using polyacrylamide gel electrophoresis. The results (Fig. 1; Tables 1 and 2) suggest that these isozymes be of the monomeric nature coded by a single locus. Five alleles were identified and designated as A, B, C, D and F respectively. No genetic difference in peroxidase isozymes was detected among the mandarins orignated from China, Japan and Indian. Man Ju may be a hybrid between Ponkan and Ougan. Ponkan may have not been involved in the origin of Jiao Gan. Zheng Jiang Jin Ju should be an infraspecific hybrid of C. reticulata. C. sinensis has a close relationship with some Chinese mandarins. Changshou Kumquat and Calamondin are shown to be intergeneric hybrids between Citrus andFortunella.

Key words: Peroxidase, Citrus, Fortunella, Taxonomy