Indirect somatic embryogenesis from mature embryo cultures of pistachio, Pistacia vera L.

Induction of somatic embryogenesis, proliferation and development of somatic embryos was obtained through different culture passages with respect to plant growth regulators. Callus cultures were initiated on callus induction medium (CIM) containing Murashige and Skoog (MS) salts with Gamborg vitamins supplemented with 2.0 mg l(-1)2,4-dichlorophenoxyacetic acid (2,4-D) and 40 g l(-1) sucrose from mature zygotic embryo of pistachio. Embryogenic tissue with globular somatic embryos was obtained when the calli were initiated on Murashige and Skoog (MS) medium with Gamborg vitamins supplemented with 1-4 mg l(-1) 2,4-D or its combination with 6-benzylaminopurine (BAP). The embryogenic cultures were maintained on an embryogenesis induction medium (EIM), which contains 1-2 mg l(-1) BAP for 4 weeks. These cultures were regularly subcultured every three or four weeks on EIM. After transfer of the embryogenic tissues into the somatic embryo maturation medium (ENM) containing 0.5 mg l(-1) BAP, with various concentrations of abscisic acid (ABA) and sucrose, somatic embryos appeared. On the media with 0.5 mg P ABA and 6% sucrose the highest number of somatic embryos (42 per 250 mg of fresh weight) was formed. Adventive stages of somatic embryos were manually separated from the friable embryogenic tissues. Separated somatic embryos germinated on solidified MS medium without growth regulators, developed into plantlets.