Genotypic and media factors affecting stabilization of polyembryogenic cultures in norway spruce (Picea abies (L.) Karst.).

Embryonal-suspensor mass lines (ESM lines) from mature embryos of three open-pollinated families of Norway spruce [Picea abies (L.) Karst.] were stabilized on several culture media varying in nutrient composition. A pattern of relationship between parameters of polyembryogenic culture performance and medium composition was genetically determined. Stabilized ESM lines could be classified into two phenovariants: (i) lines of homogenous ESM composed entirely of somatic proembryos, and (ii) lines of heterogeneous ESM composed of a mixture of nonembryogenic callus and aggregates of somatic proembryos. The formation of one or the other phenovariant was independent of genotype, but strongly determined by the medium composition.