Optimization of in vitro sterilization for pistachio (Pistacia vera L.) rootstocks

Pistachio (Pistacia vera L.) is one of the leading edible nut consumed all over the World due to its nutritional values. The plant is cultivated in most of the countries alongwith Turkey which is one of the the leading grower of pistachio. In Turkey, the rootstock material is currently propagated through traditional methods and there is a need of propagating plant material using modern biotechnological techniques like plant tissue culture. The provision of contaminated free explants with minimum or no phenolic compounds in the culture medium is the prerequisite of in vitro regeneration protocol. The plant material used in this study was collected at different physiological stages during different months like April- June and Sep-October. The plant material was cut into 2-3 cm long nodal segments followed by cleaning with different agents like water, soap and fungicide prior to subjected to sterilizing agents. Different sterilizing agents used in this study were HgCl2, Huwa-san (H2O2) and commercial bleach (NaOCl) for both rootstocks (UCB-1 and Buttum) with different exposure time. Sterilized explants were cultured on MS basal medium containing plant growth regulators and subcultured once a week for three weeks. Results revealed that HgCl2 as sterilizing agent was more superior than other sterilizing agents for both rootstocks. Among rootstocks, UCB-1 was more responsive than Buttum and relatively more sterilized plants were attained. On the other hand, plant material collected during June responded better and 90.0% and 50.0% sterilzied plants were attained for UCB-1 and Buttum respectively. The results revealed the significant impact of collection time, sterilizing agent type, concentration and exposure time on sterilization of P. vera rootstocks.