Evidence for early stages of somatic embryo development in a protoplast‐derived cell culture of <i>Prunus avium</i>

Abstract

In the genus Prunus , so far, somatic embryogenesis has not been reported either from cell suspensions or from their protoplast‐derived cells. Rhizogenic cell suspensions of Prunus avium L., initiated from adventitious roots developed from cotyledon‐derived callus of mature zygotic embryos, have been subcultured for more than one year without losing their morphogenic potential. A yield of 8 × 10 5 protoplasts ml −1 of packed cells with a viability of 98% has been routinely obtained. Optimum cell division frequency (around 2.5% at day 10 and 4–6% at day 15) occurs in agarose lenses, with Murashige and Skoog (1962. Physiol. Plant 15: 476–497)‐based medium supplemented with 5 μ M naphthalene acetic acid, 1 μ M benzyladenine and 0.25 μ M zeatin. Colony formation has been achieved after 35 days with a plating efficiency of 3–4%. Cell suspensions have been initiated from protoplast‐derived callus. While the older cell cultures express a rhizogenic response, the younger ones contain early stages of somatic embryo development. Ultrastructural examination confirms the polarization of these structures.