ORGANOGENESIS AND SOMATIC EMBRYOGENESIS IN CALLUS-CULTURES OF ROSA-HYBRIDA AND ROSA-CHINENSIS-MINIMA

Pre-incubation of somatic tissues of the cut rose 'Carefree Beauty' an d miniature roses 'Red Sunblaze' and 'Baby Katie' in 10, 100, or 200 m u M 2,4-D induced the development of highly rhizogenic callus. Upon tr ansfer of rhizogenic callus to a regeneration medium containing 23 mu M TDZ and 3 mu M GA(3), a low frequency of shoot organogenesis (3.3%) and somatic embryogenesis (6.6%) was observed. Incubation of leaf and stem internodes in 11, 27, 54, 81, or 108 mu M NAA followed by transfe r of explants to the regeneration medium resulted in up to a 25% incre ase in shoot organogenesis from callus-derived internodal explants of 'Red Sunblaze', but no somatic embryogenesis was observed. The influen ce of glucose versus sucrose in the regeneration medium on leaf explan ts of 'Carefree Beauty' and 'Baby Katie' pre-incubated in 100 mu M 2,4 -D revealed a difference in genotypic response to shoot organogenesis and somatic embryogenesis. For 'Carefree Beauty', a concentration of 1 11 mM glucose induced higher frequencies of both organogenic (33%) and embryogenic calluses (25%) than either 59 mM or 117 mM sucrose. For ' Baby Katie', no significant difference was found for number of organog enic calluses induced on 59 mM sucrose and 111 mM glucose.