Hülya Akdemir

Current status and conservation of Pistacia germplasm.

The genetic erosion of Pistacia germplasm has been highlighted in many reports. In order to emphasize this and to focus more attention on this subject, national and international (especially IPGRI and IFAR) institutions have initiated projects proposing to characterize, collect and conserve Pistacia germplasm. Therefore, this paper reviews recent research concerning conventional (in situ and ex situ) and unconventional biotechnological conservation strategies applied to the preservation of Pistacia germplasm. As regards conventional conservation, the majority of germplasm collections of Pistacia species are preserved on farms (in situ) and in seed and field genebanks (ex situ), as well as in the wild, where they are vulnerable to unexpected weather conditions and/or diseases. Hence, complementary successful unconventional in vitro methods (organogenesis, somatic embryogenesis and micrografting) and slow-growth storage conditions for medium-term preservation of Pistacia are presented together with the morphological and molecular studies carried out for the characterization of its species in this review. Moreover, special attention is additionally focused on cryopreservation (dehydration- and vitrification-based one-step freezing techniques) for the long-term preservation of Pistacia species. Possible basic principles concerning the establishment of a cryobank for the successful conservation of Pistacia germplasm are also discussed.

Novel Methods in Micropropagation of Pistachio

The focus of this paper is to describe the novel methods developed for the different stages of micropropagation: installation of mature apical shoot tips and elimination of browning exudates; forcing hardwood shoots from the lignified stem sections; forcing axenic leaves; initiation of embryogenic masses (EMS); encapsulation of somatic embryos and cryopreservation of axillary buds for storage, and the facilitation of rooting. These developed methods are not being used by commercial micropropagation laboratories yet. Exudation of phenolics is inhibited when the disinfested and rinsed explants are cut at the base of the shoot tips and washed twice for 1 h by shaking them in sterile distilled water on a shaker at 100 rpm. For shoot initiation, 15–20 cm long terminal stem sections are cut into 3–4 cm sections and placed in pots filled with peat, perlite and soil. Two or three weeks later, the developed softwood shoots are excised; or freshly harvested three to nine apical tips of 1–2 cm are disinfested and used as explants. Leaves excised from axenic shoot cultures were also used to induce organogenesis on a Murashige and Skoog (MS) medium with Gamborg vitamins supplemented with combinations of different concentrations of 6-benzylaminopurine (BA) and indole-3-asetic acid (IAA). Calcium alginate gel was used to encapsulate somatic embryos to produce synthetic seeds. The encapsulated somatic embryos can be stored under refrigerated conditions for short-term conservation. For long-term conservation, some axillary buds can also be stored by using vitrification and one-step freezing technique; however, other cryogenic techniques should also be tested. With these improved stages, application of Pistachio vera L. micropropagation in commercial clonal orchards will be feasible as an alternative to traditional propagation in the near future.

Biotechnological Approaches for Conservation of the Genus Pistacia

Climate change with the combination of increased population growth, unplanned urbanization, habitat loss and degradation, pollution and diseases, overexploitation of valuable species are the major causes of the loss of plant biodiversity. Moreover, since environment and environmental factors will change faster than the most of the plant’s adaptation, conservation strategies become critically essential for preservation of plant species. In this chapter, we described the current status of biotechnological conservation approaches for Pistacia species. Since in vitro conservation and most of cryopreservation methods rely on tissue culture-based methods, we described here micropropagation, micrografting, and somatic embryogenesis procedures in addition to in vitro conservation and cryopreservation in Pistacia species. Because there is no one ‘universal protocol,’ biotechnological conservation studies for Pistacia are still limited with a few species of the genus as described in this chapter. Development and optimization of appropriate techniques especially for long-term preservation of different Pistacia species can lead to establish cryobanks to conserve germplasm. Furthermore, the developed technologies will provide to prevent possible genetic erosion of Pistacia species.