Cryopreservation of Serbian autochthonous Prunus spp. by droplet-vitrification

In vitro shoot tips of Serbian autochthonous plums ‘Sitnica’ (Prunus domestica L.) and ‘Crvena Ranka’ (Prunus insititia L.) were tested for recovery after cryopreservation using the droplet-vitrification technique. After 30-min loading with 1.9 M glycerol and 0.5 M sucrose, explants were dehydrated at room temperature for 10, 20, 30, 40 and 50 min with PVS A3 solution (37.5% glycerol, 15% dimethylsulfoxide, 15% ethylene glycol and 22.5% sucrose) or for 60, 90 and 120 min using PVS3 solution (50% glycerol and 50% sucrose). Rewarming was performed in unloading solution containing 0.8 M sucrose for 30 or 60 min. Duration of PVS3 treatment significantly affected survival (27.3–72.7%) and regrowth (0–18.2%) of cryopreserved explants in plum ‘Sitnica’, with the highest values of both parameters being achieved with the 90-min treatment. Also, survival of explants dehydrated with PVS A3 solution significantly varied between 18.2–73.9%, depending on duration of both dehydration and unloading treatments. However, cryopreserved explants displayed a very low regrowth capacity, the highest being 10% for 30-min dehydration in combination with 60-min unloading. ‘Crvena Ranka’ exhibited a higher regrowth capacity after cryopreservation. Duration of PVS3 treatment significantly affected survival (22.2–77.8%) and regrowth (0–30.0%) of cryopreserved explants, with the highest values of both parameters being achieved with the shortest treatment duration. As regards PVS A3 treatments, both survival and regrowth significantly varied between 27.3–81.8%, and 0–36.4%, respectively. The highest regrowth was achieved with 20- and 30-min treatment durations combined with 30-min unloading. Further optimization of the protocol is necessary to improve recovery after cryopreservation.