Achievements on somatic embryo development in some conifers: what could be learnt? Where are we going?

Attempts to scale up somatic embryogenesis has been demonstrated in both conifers and broadleaved species. In recent years, many researches focused on somatic embryos development, namely maturation, an important step for subsequently producing vigorous somatic trees. Somatic embryo maturation is a complex process triggered by many parameters such as environmental conditions that are also depending on the species. Optimized conditions resulted in recovery of cotyledonary somatic embryos that are morphologically similar to the zygotic counterpart. The optimal duration of maturation has hitherto been determined mainly on the basis of these morphological features and the ability of somatic embryos to germinate and convert into plantlets. However, this empirical approach does not provide any accurate information about the intrinsic quality of harvested cotyledonary somatic embryos as demonstrated by physiological, biochemical and molecular analyses. Referring to different conifer model systems (larch, pine) we will present the achievements and some lessons that could be learnt for further refinement of cotyledonary somatic embryo developmen