Somatic embryogenesis as a regeneration method for clonal propagation of Mediterranean forest species

Abstract

Breeding programs and activities of conservation of genetic resources of forest species are years behind the equivalents in agriculture. Forest resources have been traditionally considered as mining supplies, in which extraction was the main object, leaving exclusively to natural regeneration the labour of maintenance of the stands. Nowadays, the necessary development of rural lands forces to a rational exploitation of resources to guarantee its sustainability. Because of that, the opinion that forest species can and must be harvested in specific areas is beginning to be spread.

Biological characteristics of forest species make them, sometimes, recalcitrant to the breeding and conservation techniques usually applied to agricultural species. Particularly, vegetative propagation has been highly used in woody harvests as an effective tool for achieving higher genetic gains, making use of the best genetic combinations. In forest species, especially the Mediterranean ones, this method of improvement has been hardly applied, due to the low morphogenetic ability and the great influence of maturation or phase change on this trait. Over the last few years, forest biotechnology has had a great development. Particularly, plant regeneration techniques based on in vitro tissue culture, mainly via somatic embryogenesis, are being used by different private firms and public institutions for the conservation of selected trees and for the establishment of clonal trials with different species.

Our research teams are developing protocols for the regeneration of different forest species via somatic embryogenesis. This work presents the actual state of knowledge in two typical Mediterranean species: cork oak (Quercus suber L.) and stone pine (Pinus pinea L.) highlighting the main bottle-necks for their application on a large scale.