PROTOPLAST TECHNOLOGY FOR THE BREEDING OF TOP-FRUIT TREES (PRUNUS, PYRUS, MALUS, RUBUS) AND WOODY ORNAMENTALS

Until recently, temperate fruit trees and woody ornamentals have been regarded as recalcitrant to biotechnological breeding approaches based on protoplasts. This however should no longer be the case, as procedu res are now available, not only for the regeneration of complete plant s from protoplasts of various tissues of such species, but also for th e exploitation of protoplast technology for their genetic manipulation . This paper will examine the recent advances and state of the art in this domain, with particular attention to the use of protoplast techno logy as a novel tool in the breeding of rosaceous top-fruit tree speci es and woody ornamentals. Problems and their solutions within the cont ext of regenerating plants from isolated protoplasts of stone (Prunus spp.), pome (Pyrus spp., Malus spp.) and small (Rubus spp.) fruits, an d of several shrubby ornamental genotypes (Lonicera spp., Weigela spp. , Forsythia spp., Cotoneaster spp.) will be addressed. Interspecific ( Prunus spinosa + Prunus cerasifera) and intergeneric (Forsythia spp. Syringa spp.) somatic hybridization within this group of species, as well as the use of protoplasts for host/pathogen interaction studies ( Pyrus/Erwinia amylovora) will also be discussed.