Norway spruce somatic embryogenesis: Membrane rafts as a compromise between liquid and solidified media

Abstract

Embryogenic cultures of Norway spruce (Picea abies) were cultivated either on solidified media, in liquid media, or on polypropylene membrane rafts (LifeRaft). The cultivation on rafts was found to be the most successful way: the number of developed somatic embryos increased, synchronization of the development was enhanced, and the time necessary for embryo development and maturation was shortened. It was shown that the process could be further improved by insertion of a pre-maturation phase on PGR-free medium between proliferation and maturation steps. Germination frequency remained unchanged. PEG 4000 added to the maturation medium increased the number of developed somatic embryos. PEG in lower concentration (1.87 % (w/v)) still had the significant beneficial effects on embryo numbers and development, but a decrease of germination frequency or increased aberrations of developing root and shoot were not found. On the other hand, PEG in the concentration 5 and 7.5 % (w/v) had a negative effect on the germination of somatic embryos and, in sensitive cell line, 7.5 % (w/v) PEG decreased somatic embryo yield.