Morpho-histological study of somatic embryo-like structures in hypocotyl cultures of Pelargonium x hortorum Bailey.

Somatic embryo-like structures were produced from the hypocotyls of ten cultivars of Pelargonium x hortorum using the protocols of Marsolais et al. (1991; Can J Bot 69:1188-1193) and Slimmon et al. (1991; Plant Cell Rep 10:587-589) and their embryonic natures evaluated. Nine cultivars responded, and 937 structures were formed. Regeneration corresponded well with published data. The somatic embryo-like structures were globular- to leaf-shaped or similar to shoots. A root pole was never visible. Histological examinations confirmed the lack of bipolarity and revealed vascular connections to the explant in the more developed structures. Therefore, these structures cannot be classified as somatic embryos. The importance of these results is discussed in terms of evaluating published protocols for the propagation of these pelargoniums by somatic embryogenesis from hypocotyls.