Application of Tissue Culture to the Germplasm Conservation of Temperate Broad-Leaf Trees

Abstract

The recovery and conservation of a broad genetic pool of wild and domesticated species are essential for the maintenance of plant biodiversity. Traditionalex-situconservation systems (i.e., seed and field collections), alongsidein-situconservation, make a fundamental contribution to the preservation of plant genetic resources. Up to now these approaches have been the only reliable option for the long-term germplasm preservation of woody species, although they have several drawbacks. Numerous forest Angiosperms (e.g.,Acerspp.,Quercusspp., chestnut, horsechestnut, many tropical species) have non-orthodox (recalcitrant) seeds that quickly loose their viability or are subject to a rapid decrease in germinability during storage (Pence, 1995). Moreover, recalcitrant seeds do not tolerate the level of dessication that is commonly required to prolong conservation (Roberts, 1973). As regards temperate fruit trees, the majority of the species belonging to this group are reproduced by vegetative propagation, thus requiring the conservation in clonal orchards of huge numbers of accessions, including old and newly selected cultivars, local varieties and wild material. Table 1, for instance, gives a clear idea of the efforts required today for the preservation of the EuropeanPrunusgermplasm, kept in the field repositories of 21 countries.

Table 1 Summary of Pnmus field collections in 21 European countries (from Gass et al., 1996).