Response of Abies alba embryonal-suspensor mass to various carbohydrate treatments.

Cultures of embryonal-suspensor mass of European silver fir (Abies alba) were screened for their response to various sucrose concentrations (29-175 mM) and to equimolar (100 or 200 mM) concentrations of glucose, fructose, galactose, sucrose, lactose and soluble starch. The higher concentrations were combined with 3.78 μM abscisic acid. While fructose was ineffective in promoting any somatic embryo maturation glucose, sucrose and galactose promoted early maturation stages. Somatic embryo development up to the torpedo stage was observed only on media with soluble starch or lactose. Lactose was superior to other carbohydrate treatments and led to more synchronized maturation and more normally structured embryos. In comparison with the pronounced carbohydrate effect abscisic acid at this concentration proved to be of less importance. A sequence of culture steps was established in order to stimulate differentiation and maturation.