DEVELOPMENT AND GERMINATION OF ABIES-ALBA SOMATIC EMBRYOS

Mature zygotic embryos of Abies alba mull were placed on a modified MCM medium (basal medium - BM) with 2.2 mu M benzyladenine and 2.3 mu M kinetin to induce embryogenic suspensor masses (ESM). These ESM proliferated on induction medium supplemented with 0.2 mu M 2,4-dichlorophenoxyacetic acid. From 61 ESM lines induced, 36 are still in culture after 2 years, of which 18 show embryogenic potential indicated by spontaneous formation of globular somatic embryos on the proliferation medium supplemented with 500-1000 mg 1(-1) casein hydrolysate and 500 mg 1(-1) L-glutamine. ESMs from cell line 2/56 were conditioned 1 week on BM with 58 mM sucrose and 10 g 1(-1) activated charcoal for maturation of somatic embryos. Maturation was achieved on BM containing 20 mu M (+/-)cis-trans-abscisic acid in combination with Ill mM maltose. Organic nitrogen supplements improved the proliferation rate of cell line 2/56 as well as the maturation and vitality of the somatic embryos. Partial drying was necessary for subsequent root development. Plantlets with a root, primary needles and a terminal bud developed on BM when a combination of 30 mM sucrose and 50 mM maltose was provided as carbon source.