Somatic hybrid plants from sexually incompatible woody species: Citrus reticulata and Citropsis gilletiana

Summary Allotetraploid intergeneric somatic hybrid plants between Citrus reticulata Blanco cv. Cleopatra mandarin and Citropsis gilletiana Swing. & M. Kell. (common name Gillet's cherry orange) were regenerated following protoplast fusion. Cleopatra protoplasts were isolated from an ovule-derived embryogenic suspension culture and fused chemically with leaf-derived protoplasts of Citropsis gilletiana. Cleopatra mandarin and somatic hybrid plants were regenerated via somatic embryogenesis. Hybrid plant identification was based on differential leaf morphology, root-tip cell chromosome number, and electrophoretic analyses of phosphoglucose mutase (PGM) and phosphohexose isomerase (PHI) isozyme banding patterns. This is the first somatic hybrid within the Rutaceae reported that does not have Citrus sinensis (sweet orange) as a parent, and the first produced with a commercially important citrus rootstock and a complementary but sexually incompatible, related species.Abbreviations PGM phosphoglucose mutase - PHI phosphohexose isomerase - MES 2N-morpholino] ethane sulfonic acid - BH3 protoplast culture medium (Grosser and Chandler, 1987) - PEG polyethylene glycol - MT Murashige and Tucker (1969) basal medium - NAA 1-naphthaleneacetic acid - GA3 gibberellic acid - H+H and EME citrus embryogenic cell culture media (Grosser and Gmitter, 1990b) - B embryo germination medium - RMAN rooting medium Florida Agricultural Experiment Station Journal Series No. R-00298.