SOMATIC HYBRIDIZATION BETWEEN CITRUS RETICULATA AND CITROPSIS GABUNENSIS THROUGH ELECTROFUSION
Protoplasts were isolated from embryogenic calli of Citrus reticulata cv. Ponkan and Citropsis gabunensis, and fused in electric fields. The maximal fusion efficiency was obtained by application of AC at 75 V/cm (1.0 MHz) and DC square-wave pulse at 1.125 KV/cm for 40 usec. Fusion-treated protoplasts were cultured on MT medium without phytohormone, solidified with 0.6% agar. Colonies from the protoplasts were proliferated on MT medium with zeatin 1 mg/l and 0.9% agar. Selection of somatic hybrid callus was based on chromosome count and isoenzyme analysis. The somatic hybrids were tetraploid (2n=36). C. reticulata and C. gabunensis were both homozygous at Got-1 locus, but distinguishable easily because band of the latter migrated faster than that of the former. In zymogram of somatic hybrid, both parent bands were retained and a new hybrid band was also evident between them. Embryos from somatic-hybrid callus regenerated intact plant. The hybrid plants showed intermediate morphological characteristics of the parents.