Cryogenic Storage of Apple (Malus domestica) Shoot Tips Using Encapsulation-dehydration

Shoot tips of apple (Malus domestica) derived from in vitro cultures were used as explants in this study. Several pretreatments prior to cryogenic storage were conducted to enhance shoot tips recovery after cryostorage. The optimal procedure was as follow: excised shoot tips were precultured on solid Murashige and Skoog Medium Supplemented (MS) with 0.3 M sucrose, encapsulated in calcium alginate beads, precultured in liquid medium with 0.75 M sucrose for 1 day, and desiccated to 15-29% moisture content (fresh weight basis), and then immersed rapidly in liquid nitrogen. The encapsulated dehydrated shoot tips cooled to -196 °C produced a high (72%) level of regrowth. This method is promising for cryogenic storage of Malus domestica shoot tips