SOMATIC HYBRIDS OBTAINED BY FUSION BETWEEN PONCIRUS-TRIFOLIATA (2X) AND FORTUNELLA-HINDSII (4X) PROTOPLASTS

Somatic hybrids were obtained by the symmetric fusion of embryogenic c allus cells from tetraploid 'Mame' kumquat [Fortunella hindsii (Champ. ) Swing.] and mesophyll cells from diploid trifoliate orange [Poncirus trifoliata (L.) Raf.]. Southern blot analysis of three regenerants re vealed that they carried specific rDNA fragments from both fusion part ners, thereby confirming their hybridity. In contrast, mitochondrial D NA (mtDNA) and chloroblast DNA (cpDNA) were unidirectionally transmitt ed from the callus parent without any evidence of recombination. No di fferences in the restriction fragment patterns of rDNA, mtDNA or cpDNA could be detected among the regenerants. Flow cytometry showed that t wo regenerants were hexaploids; as expected, but that one was pentaplo id, probably due to elimination of chromosomes prior to the regenerati on of this plant.