Cryopreservation of in vitro grown shoot-tips of Olea europaea L-var. Arbequina

A simple cryopreservation method is described for olive in vitro grown apic al shoot-tips. It involves preculturing the meristematic dome with 1 or 2 p airs of leaf primordia for 2 days in culture medium enriched with 0.75 M su crose, followed by dehydration in the air current of a flow cabinet for 2 h (30% moisture content), transference to cryovials, plunging into liquid ni trogen for storage and rewarming at room temperature. A progressive decreas e in survival was achieved both for control and frozen samples as the dehyd ration period was increased Shoot recovery rates were around 30% for dried and frozen samples which was equivalent to 77% of those surviving dehydrati on alone. Thermal transitions in samples cryopreserved by this procedure sh owed absence of enthalpy changes and glass transition phases occurred betwe en -45 and -55 degrees C for cooling and rewarming.