GENOTYPE AND PARENTAL COMBINATION INFLUENCE EFFICIENCY OF CYBRID INDUCTION IN CITRUS BY ELECTROFUSION

Interspecific hybridizations by electrofusion of embryogenic callus ce lls from 'Seminole' tangelo (Citrus reticulata Blanco x C. paradisi Ma cf.), 'Hazzara (Abohar)', or 'Ohta' ponkan (C. reticulata Blanco) and leaf cells from 'Lisbon' lemon [C. limon (L.,) Burm, f.] or rough lemo n (C. jambhili Lush.), respectively, were performed, Electrofusion of 'Seminole' tangelo and 'Lisbon' lemon, 'Hazzara (Abohar)' and rough le mon, and 'Ohta' ponkan and rough lemon resulted in 33, 43, and 36 plan ts, respectively, Seven to 10 plants in each combination were selected randomly and used to investigate nuclear and cytoplasmic genomes, Reg enerated plants derived from electrofusion of 'Seminole' tangelo and ' Lisbon' lemon, and 'Hazzara (Abohar)' and rough lemon possessed the sa me restriction fragment pattern for nuclear rDNA as that of the mesoph yll parents and the same mitochondrial DNA (mtDNA) restriction pattern as that of the respective suspension parents, indicating that they we re cybrids, In contrast, all the plants resulting from a combination b etween 'Ohta' ponkan and rough lemon were confirmed by nuclear rDNA an d mtDNA analysis to be somatic hybrids, The analysis of chromosome num ber supported the results of Southern blot hybridization, The results suggest that specific cell lines, parental combinations, or both can i ncrease the efficiency of inducing cybrids in Citrus by electrofusion.