Application of Cryopreservation for Pistachio Germplasm Conservation

Pistachio (Pistacia vera L.) which has an economical importance especially for Mediterranean countries, is today under the threat of genetic erosion. Therefore, it is very important to develop efficient biotechnological strategies for the safeguard conservation of pistachio biodiversity. Currently, cryopreservation is the only technique available that enables to maintain plant germplasm without alteration or modification for a theoratically unlimited period of time. Hence, in this study experiments were conducted to develop and optimize efficient cryogenic protocols for the preservation of seeds and axillary buds of pistachio. By using dehydration and one-step freezing technique, 90% germination was obtained with decreasing the moisture content of the seeds to 11.7% (FW basis) by 8 hours drying over silica gel prior to their direct immersion in liquid nitrogen (LN). As regards the long-term preservation of axillary buds of in vitro-grown pistachio shoots, vitrification and one-step freezing technique was also tested with incubation of buds in PVS2 solution for various periods of time (0, 30, 60, 90 min) and different temperatures (0 degrees C and 25 degrees C) before immersion in LN. Following the optimization of the vitrification protocols, trials are now in progress for the development of effective cryopreservation protocols for pistachio axillary buds both by using encapsulation-vitrification and encapsulation-dehydration techniques.