Genetic variation in microsatellite stability of somatic embryo plants of Picea abies: A case study using six unrelated full-sib families

Clonal propagation by somatic embryogenesis is a promising approach to preserve and multiply elite genotypes in tree breeding and reforestation programmes of conifers. The principal requirement for the large-scale application of this approach is near uniformity of the plants regenerated from somatic embryos. Picea abies families varied significantly in genetic stability, as shown by allele frequencies at four variable nuclear microsatellite loci in 314 plants regenerated from somatic embryos from six families. Furthermore, in some clones only one or two plants carried the mutated allele, while in other clones all the plants carried the same mutation. Relative growth increment was not affected in somatic embryo plants carrying mutated microsatellite alleles. For comparison, seedlings from half-sib families were analysed for microsatellite variation. Mutated alleles were detected in three of the 208 seedlings analysed. The allelic distribution of microsatellites in clones derived from somatic embryos was not significantly different from that of the parents. This suggests that the procedure for somatic embryogenesis does not give any large changes in allele frequency.