Organogenesis response of six selected half-sibling families of stone pine (Pinus pinea L.) has been evaluated, showing genotype-dependent behaviour. The caulogenic phase was characterized by high values of Survival and Organogenesis, while the rooting phase (the bottleneck of many coniferous species) showed great variability among families. Provenance influence was also studied, and the rhizogenesis protocol was optimized for the selected families. The highest values were obtained with family 36, with 100% of Organogenesis, a Bud Formation Capacity (BFC) Index of 6.54 and 38.44% of Rooted Shoots; on the other hand, family 61 presented the worst results, with 83.64% Organogenesis, a BFC Index of 3.01 and a 29.69% Rooting Rate. According to these results, both families will be used in further experiments looking for the underlying bases of the different organogenic behaviour between both families under the same culture conditions. In addition to this, and for the first time in this species, random amplified polymorphism DNA (RAPD) analysis has been carried out to determine whether somaclonal variation had occurred. The results suggested an absence of variation during the whole in vitro process, although more thorough studies would be required for a conclusive answer.
