Properties of rescued embryonal suspensor masses of Norway spruce determined by the genotype and the environment in vitro.

Fifty three genotypes of embryonal suspensor masses (ESMs) rescued from mature seeds of Norway spruce (Picea abies L. Karst.) were examined for their pattern of growth and development under standardized culture conditions in vitro. Patterns were classified according to the color of the colonies grown in darkness, clarity of cell masses and proembryos in the mucilaginous ESM, surface boundary topology of colonies, structure of suspensors, growth rate of the ESM, and recovery of mature embryos. Five distinctive major growth patterns were observed among ESM colonies under standardized culture conditions. The multiplication of proembryos and early embryos by cleavage and budding polyembryony was the main factor contributing to proliferation and colony growth and further determined the morphology of the colonies. Callus and teratological structures were induced from early embryos by changing the standardized culture conditions i.e. inadequate subculture, excessive dose of 2,4-D in the medium and premature exposure of the colonies to light. Results enable the selection of ESM genotypes for the more predictable recovery of mature somatic embryos