Early Events in Somatic Embryogenesis Induction

Abstract

In Plant Kingdom, one of the strategies for plants to survive is the spontaneous production of direct somatic embryos [1]. Examples can be found in angiosperms, both in dicots and monocots. In artificial conditions, somatic embryogenesis is achieved using different types of initial expiants and following different types of stress [for a review see, 1,8,9,11,12]. Although both direct and indirect somatic embryogenesis have been successfully achieved for many species [9], the knowledge on the early events occurring during the induction of embryogenesis is still scarce. Here, we describe some of the molecular and elemental changes occurring during the early stages of direct somatic embryogenesis using, as model plant, the woody species Camellia japonica. Our previous results shown that direct embryogenesis from camellia leaves is region specific [5]. This specificity was suggested to be related to pre-established elemental gradients, namely, of calcium, sodium and sulphur [4,6]. After the induction treatment, two types of response were detected: a “fast” and a slower one [6]. The first one, common to all parenchyma cells, was suggested to be a stress response, due to leaf excision and to the induction treatment. The following morphogenic or non-morphogenic responses, that were cell or explant-region specific, were suggested to be dependent on the cell-state of each cell at the time of leaf isolation [6]. Some data on the possible effect of stress on embryogenic induction is presented. The role of Ca2+, Mg2+ and competing polyamines (free and conjugated) on cell division and morphogenesis is also discussed.KeywordsSomatic EmbryoSomatic EmbryogenesisInduction TreatmentDirect Somatic EmbryogenesisSomatic Embryogenesis InductionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.