Biochemical events during germination and early growth of somatic embryos and seed of interior spruce (Picea glauca engelmannicomplex)

Utilization of lipid and protein storage reserves was examined during germination and early growth of somatic and excised seed embryosin vitro, and seed of interior spruce. High germination frequencies were recorded for somatic and excised seed embryos, and elongation of radicles and hypocotyls observed for both embryo types. Although elongation of the embryo types differed (i.e. somatic ≤ excised seed < seed), fresh weight gain was similar. Utilization of triglycerides in somatic embryos was more rapid than in excised seed and seed embryos, thus it appeared to be under embryo infuence. By contrast, depletion of storage proteins appeared to be influenced by the megagametophyte, with hydrolysis in somatic and excised seed embryos preceding that of the seed embryo by 2 days. Differential utilization of the storage reserves was temporally associated with differences in growth patterns of somatic and seed embryos. The evidence presented indicates that thein vitrogermination medium does not entirely supplant the role of the megagametophyte during germination and early growth. The relevance of these results to artificial seed technology is discussed.