Changes in competence for somatic embryogenesis in Norway spruce zygotic embryo segments

Embryogenic capacity of Norway spruce zygotic embryo sections was drastically altered by a preinduction transfer to hormone-free medium for 7 or 14 days. An increase in competence for somatic embryogenesis was found with the cotyledons, while the hypocotyl sections completely lost their competence. These changes in competence were not dependent on physical contact between plant sections, and could not be correlated to the developmental stage of each section. The increase of competence in cotyledonary material was due not only to an increase of genotypes initiating somatic embryos, but also to an increase in embryogenicity of cotyledons.