Abdelmalek El Meskaoui 1 *, Yves Desjardins 2 and Francine M. Tremblay 3

1 Institut National des Plantes Médicinales et Aromatiques, Taounate, Université Sidi Mohammed Ben Abdellah, Fès, Maroc
2 Centre de Recherche en Horticulture, Envirotron, Université Laval, Québec, Qc, Canada, G1K 7P4
3 Centre de Recherche en Biologie Forestière, Pavillon C.-E. Marchand, Université Laval, Québec, Qc, Canada, G1K 7P4.

Abstract

The objective of the current study was to determine the effects of the gaseous environment on conifer somatic embryos and to understand how the gaseous environment in the culture tissue system may influence the maturation. At the first time, the effect of confined and vented gaseous microenvironments (tightly sealed and vented containers) on the maturation of somatic embryo of white spruce was examined. The results showed that confined microenvironment promoted a higher production and uniformity of mature somatic embryos and prevented the precocious germination in comparison to vented environment. Reducing air exchange may be useful to synchronize the maturation stage. The headspace gas analyses of confined environment revealed a marked CO 2 accumulation (33.6 %), correspondent O 2 consumption (2.3 %) and C 2 H 4 accumulation (7 µl/l). To determine how the gaseous environment influenced the somatic embryo maturation, the effects of oxygen, and carbon dioxide were evaluated during the maturation stage of black spruce and white spruce. The results show that the addition of 5% CO 2 or 10% O 2 promoted somatic embryos in both spruce species. The beneficial effect of these gases on somatic embryo formation might be explained by their action on ethylene biosynthesis pathway since reduced oxygen concentration resulted in a marked increase of the endogenous levels of 1- aminocyclopropane-1-carboxylic acid (ACC) in embryogenic tissues of white spruce. Abbreviations — ABA, abscisic acid; ACC, 1-aminocyclopropane-1-carboxylic acid; FID, flame ionization detector; GC, gas chromatography; HLM, half Litvay's medium.