REGENERATION OF SOMATIC HYBRID PLANTS OBTAINED BY ELECTRICAL FUSION BETWEEN SATSUMA MANDARINE (CITRUS-UNSHIU) AND ROUGH LEMON (C-JAMBHIRI) OR YUZU (C-JUNOS)

Electrical fusion of protoplasts was used to produce somatic hybrids between satsuma mandarin cultivar 'Saruwatari' (Citrus unshiu MARC.) and rough lemon (C. jambhiri LUSH.) or yuzu (C. junos SIEB, ex TANAKA). The optimum parameters of electrical fields were identified, however, these parameters depend on species, cell lines or cell conditions used. The final fusion efficiency (rates of binuclear heterokaryons) were around 15%. The fusion products were cultured using the method of OHGAWARA et al. (1985) and embryoids were grown according to our shuttle callus system (HIDAKA and OMURA 1989). The rDNA analysis confirmed that the somatic hybrid from these two combinations have genomes from both parents. Root tip cells of regenerated plants had the tetraploid chromosome number (2n = 36) as expected. The electrical fusion system described here is simple and more efficient than the polyethylene glycol method for producing somatic hybrids of citrus.