Cryopreservation of bitter almond (Amygdalus communis l.) shoot tips by encapsulation-dehydration and vitrification

Abstract

This study was directed towards cryopreservation of shoot tips of bitter almond (Amygdalus communis) using encapsulation-dehydration and plant vitrification solution (PVS2) techniques. For encapsulation-dehydration, microshoots were precultured on a medium containing 0.3 M sucrose and exposed to cold acclimation (5°C) for 0, 3 or 5 weeks. Shoot tips were then excised and treated with a medium containing 0.5 or 0.75 M sucrose for one day before dehydration for 4 or 6 hr. Highest survival (77 or 80%) or regrowth (50 or 60%) rates were obtained with cryopreserved shoot tips that were dehydrated for 4 or 6 hr, respectively, and pretreated with 0.75 M sucrose after 5 weeks of cold acclimation. Other microshoots were cold acclimated at 5°C for 0, 2 or 4 weeks on media supplemented with 0.3 M sucrose. Shoot tips were then treated with PVS2 for 60, 90 or 120 min at 0°C before liquid N 2 . Highest survival (93 or 1110%) and regrowth (57 or 67%) rates were obtained for shoot tips that were cold acclimated for 2 or 4 weeks, respectively, and treated with PVS2 for 120 min.