ORIGIN AND ONTOGENY OF SOMATIC EMBRYOS IN HEVEA-BRASILIENSIS (EUPHORBIACEAE)

In Hevea, currently described culture conditions allow the induction of two modes of embryogenesis in callus formed on excised portions of the internal integument of immature seeds. One mode is of unicellular origin and is transitory, only resulting in the production of globular proembryos. The other is of multicellular origin and produces embryos. Specific culture conditions appear to favor one or the other mode of development in a given genotype. The ontogenesis of embryos of multicellular origin bypasses the classical stages of zygotic embryogenesis. The structural abnormalities observed in most somatic embryos are probably responsible for the low germination rates obtained.