Enhancement of somatic embryogenesis in Norway spruce (Picea abies L.).

Embryogenic callus developed in 55% of the mature embryo explants of Norway spruce (Picea abies L.) growing on a LP medium minus the amino acids and sugars (except sucrose). This is the highest reported yield of embryogenic callus from mature embryos of P. abies that has ever been reported. Callus induction from either the middle or the end of the hypocotyl of the embryos began after 2-3 weeks. Three types of calli were recovered: (a) globular, (b) light green-compact, (c) white mucilaginous. Only the white mucilaginous calli were embryogenic. The globular and light green-compact calli never become embryogenic, even after several subcultures. The development of somatic embryos was accomplished on half-strength macro-elements of NSIII medium containing 1 μM α-naphthaleneacetic acid, 1 μM abscisic acid, and 3% sucrose. The addition of 10(-7) M buthionine sulfoximine to the medium increased the development of somatic embryos by three fold. These results suggest that there is a great potential for increasing the frequency and development of somatic embryos in P. abies. Careful selection of the genotype and modification of the culture medium is required.