A comparative evaluation of the application of somatic embryogenesis, rooting of cuttings, and organogenesis of conifers

Abstract

Vegetative propagation of conifers has found large-scale industrial application via somatic embryogenesis (SE), rooting of cuttings, and organogenesis. Genetic gain is achieved with all of these methods but is the highest with SE, primarily because SE cultures can be cryopreserved. This allows for plants derived from part of each cell line to be field tested over a long period while the rest of each cell line is kept in a juvenile state by cryopreservation for later use. This makes it possible to select the best performers within the best families. For rooting of cuttings and organogenesis, genetic gain is generally based on family average, which is less powerful. However, SE has its limitations, primarily because its initiation, maturation, or germination rates are too low to be effective for many species. Consequently, for many species, the preferred clonal propagation option is still rooting of cuttings or organogenesis. If better methods can be developed to keep ortets used for rooting of cuttings and organogenesis in a prolonged juvenile state, or if future developments in marker technology reach a point where within-family selection becomes possible without the aid of cryopreservation, rooting of cuttings and organogenesis will achieve the same genetic gain as SE.