Influence of Nitrogen Balance of Culture Medium on Norway Spruce [Picea abies (L.) Karst] Somatic Polyembryogenesis: High Frequency Establishment of Embryonal-Suspensor Mass Lines from Mature Zygotic Embryos

Artículo

Proliferating embryonal-suspensor masses (ESMs) were initiated from mature open-pollinated seeds of a northern Norway spruce (Picea abies (L.) Karst) family possessed a relatively low level of embryogenic activity. Different nitrogen content modifications of the half-strength von Arnold and Eriksson (~ LP) basal medium were tested for both the induction of ESM formation and the establishment of ESM lines. Both organic and inorganic nitrogen strongly affected the ESM line establishment. Amide nitrogen (asparagine or glutamine) was an obligatory prerequisite for the ESM line establishment and prolonged maintenance. The optimal ammonium! nitrate molar ratio in the presence of 3.0 mM glutamine was about 0.2. The highest frequency ESM line establishment (33 percent) was obtained with 7.5 mM ammonium, 33.8 mM nitrate and 3.0 mM glutamine. Somatic embryo maturation was determined by the combined effects of the nitrogen balances of maintenance and maturation media. After a two-step maturation procedure, mature somatic embryos were successfully germinated and transferred ex vitrum.