Cryopreservation of Serbian autochthonous plum ‘Crvena Ranka’ using aluminium cryo-plates

Abstract

?Crvena Ranka? is one of the oldest autochthonous plum cultivars in Serbia. However, it is endangered due to the long-term pathogen pressure and continuous suppression by commercially important cultivars and therefore faced with genetic erosion. This study was carried out to investigate the suitability of two efficient and simple cryopreservation methods using aluminium cryo-plates for its conservation. Precultured shoot tips of this genotype were embedded in alginate gel into cryo-plates wells. Osmoprotection was performed using loading solution with 1.9 M glycerol and 0.5 M sucrose (30 min at room temperature). In the V cryo-plate protocol, explants were dehydrated at room temperature for 20 or 40 min with PVS A3 (37.5% glycerol, 15% dimethylsulfoxide, 15% ethylene glycol and 22.5% sucrose) or with PVS3 (50% glycerol and 50% sucrose) for 60 min. In the D cryo-plate protocol, desiccation for 2, 2.5 or 3 h was performed over silica gel. Then, the cryo-plates were directly immersed into liquid nitrogen. Unloading was done in MS medium containing 0.8 M sucrose (30 min at room temperature). In the V cryo-plate procedure regrowth of cryopreserved explants dehydrated with PVS A3 was between 50% and 51.9%, while in those dehydrated with PVS3 it was 66.7%. As for the D cryo-plate method, regrowth of cryopreserved explants ranged between 30-40%. After regrowth, shoots were successfully multiplied and rooted. Results prove the feasibility of these new cryogenic methods for a long-term storage of this valuable Prunus genotype.