SOMATIC EMBRYOGENESIS AND PLANT-REGENERATION IN FLORIBUNDA ROSE (ROSA-HYBRIDA L) CVS TRUMPETER AND GLAD TIDINGS

Somatic embryogenic callus was initiated from in vitro-derived petiole and root explants, but not leaves, of the Floribunda rose cultivars T rumpeter and Glad Tidings following repeated subculture of callus on S chenk and Hildebrandt (SH) medium containing 2,4-dichlorophenoxyacetic acid (2,4-D). The use of a high auxin pretreatment increased the freq uency of somatic embryogenesis, whilst L-proline, as a media supplemen t, had a critical role in enhancing somatic embryogenesis in the early stages of culture but increased the frequency of abnormal embryo form ation when used in the later stages of culture. Maturation of somatic embryos was achieved by transfer to SH medium with reduced concentrati ons of 2,4-D and incorporation of abscisic acid (ABA) and 6-benzylamin opurine (BAP). The use of SH medium containing BAP and indole-3-butyri c acid (IBA) facilitated embryo germination which was also enhanced by cold treatment. Phenotypically normal plants were recovered from germ inated somatic embryos and successfully transferred to the glasshouse for flowering.