Abstract

In vitro grown apricot (Prunus armeniaca L.) cv. El-Hamawey shoot tips were successfully cryopreserved using an encapsulation-dehydration procedure. Shoot tips were encapsulated in calcium-alginate beads before preculture on woody plant (WP) medium supplemented with different sucrose concentrations; 0.1, 0.3, 0.5, 0.75 and 1.0 M for 2, 4, 6 and 8 days at 25°C. Encapsulated shoot tips were then dehydrated by incubation in the sterile air flow of a laminar air-flow cabinet for 0.0 - 6 h and immediately plunged into liquid nitrogen (LN, -196°C). The highest survival (100%) and regrowth (92.3%) rates were obtained with encapsulated unfrozen apricot shoot tips that were precultured on WP medium containing 0.5 M sucrose for two days and followed by dehydration for 2 h. After recovering from liquid nitrogen and rapid thawing in a water bath at 38°C for 2 to 3 min, the greatest survival (74.5%) and regrowth (71.8%) were obtained and encapsulated shoot tips were precultured for two days in WP medium containing 0.75 M sucrose dehydrated for 2 h, desiccated to 19.55% moisture content and conserved three months in liquid nitrogen. After two years in liquid nitrogen storage, the greatest regrowth percentage (60.4%) was obtained when encapsulated cryopreserved shoot tips were precultured for two days in medium containing 0.75 M sucrose and also with 2 h of dehydration. This study has successfully developed a simple and effective protocol for the cryopreservation of apricot shoot tips. Genetic stability of plantlets derived from cryopreserved shoot tips was evaluated using random amplification of polymorphic DNA (RAPD) markers.

Key words: Apricot (Prunus armeniaca L), cryopreservation, encapsulation/dehydration, RAPD.

Abbreviation

RAPD,   Random   amplification   of  polymorphic   DNA;  PCR,

polymerase chain reaction; WP, woody plant; IAA, indole-3-acetic acid; IBA, indole-3-butyric acid; NAA, naphthalene acetic acid; BA, Benzyl adenine; 2iP, N6-Δ²-isopentenyl adenine; LN, Liquid nitrogen; WP, woody plant.