Further steps for application of droplet vitrification for cryopreservation of Pyrus and Prunus species

Among techniques applied for cryopreservation of temperate fruit tree species there are the vitrification (V) and a modification of this method, the dropletvitrification (DV). Rosaceae family comprises a large number of fruit species, included Pyrus spp. and Prunus spp., which are of great economic importance in temperate regions. The aim of this work was to define a cryopreservation protocol, based on vitrification methods, to be applied for preserving agrobiodiversity in pear (Pyrus communis L.) and Prunus spp. In P. communis DV was compared with V applying plant vitrification solution 2 (PVS2) or plant vitrification solution 3 (PVS3) for 0, 60 or 90 min in the "Pyrus dwarf" rootstock. Regrowth was only obtained with DV and PVS3 and ranged from 9 to 41% with the immersion of the explant for 60 or 90 min, respectively. A comparison between PVS2 and PVS3 using DV was also carried out in the rootstock 'Gisela 6((R))', Prunus cerasus x Prunus canescens, applying the solutions for 0, 60, 90 or 120 min. In this hybrid PVS2 was more effective than PVS3 allowing to obtain about 40% of regrowth when applied for 120 min. These results represent the preliminary steps, performed on model genotypes, toward establishment of cryopreservation protocols for endangered Italian local varieties in Prunus and Pyrus spp.