Cryopreservation of highbush blueberry, strawberry, and saskatoon using V and D cryo-plate methods and monitoring of multiplication ability of regenerated shoots

Abstract

The purpose of this work was to apply V and D cryo-plate methods for cryopreservation of Vaccinium corymbosum ʻToroʼ, Fragaria × ananassa ʻCleryʼ, and Amelanchier alnifolia (Nutt.) M. Roem. and to monitor the multiplication capacity of shoots regenerated from cryopreserved explants. Shoot tips pre-cultured for 1 d at 23°C in the dark on medium containing 0.3 M sucrose were used as explants. Loading was performed in a solution containing 2 M glycerol and 0.8 M sucrose (30 min at room temperature). In the V cryo-plate, dehydration was carried out at room temperature (20 to 50 min) using the following plant vitrification solutions: original PVS2, 90% PVS2 solution, and PVS3. Regarding the D cryo-plate, dehydration was performed in closed glass containers over silica gel for 2, 2.5, or 3 h. In both protocols, rewarming was carried out in a 1.0 M sucrose solution (15 min at 25°C). Regenerated shoots were multiplied and multiplication parameters were monitored after the second subculture. Using the V cryo-plate method, the highest regrowth in highbush blueberry was obtained following 50-min treatment with all three VSs (61.7 to 80.9%). The D cryo-plate method was even more suitable with maximum regrowth of 89.4% achieved after 2.5 h of desiccation. For strawberry, 62.5% was the highest regrowth recorded using PVS3-based V cryo-plate method while 83.3% of regrowth was observed using D cryo-plate protocol. Regrowth of saskatoon reached a maximum of 50% after 50-min treatment with PVS3 while it did not exceed 40% in other treatments. By the second subculture, shoots regenerated from cryopreserved explants regained and even exceeded the multiplication capacity of shoots regenerated from non-cryopreserved explants. This study is the first to present the successful application of the V cryo-plate method in highbush blueberry, as well as the utilization of both V and D cryo-plate methods in saskatoon.