108 2(3): 108-112 (2013) Effect of different plant growth regulators on callus induction of stem explants in Pistacia atlantica subsp. kurdica P. Aghaei, B. Bahramnejad* 1 , A. A. Mozafari 2 1 Department of Agricultural Biotechnology, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran 2 Department of Horticulture, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran *Corresponding author: b.bahramnejad@uok.ac.ir Abstract Wild pistachio (Pistacia atlantica subsp. kurdica) is one of tree species that cover much of the forest in northwest of Iran and used in industries, medicine and as food. The present study describes callus induction of the P. atlantica subsp. kurdica using seedling stem explants and the influence of different plant growth regulators including kinetin, benzyladenine (BA), thidiazuron (TDZ), 6- Benzylaminopurine (BAP) on the growth of calli. To determine the best concentration and composition of plant growth regulators to induce callus in wild pistachio, 13 treatments were compared in a completely randomized design with five replicates. Explants were excised from 7-10 days old in vitro grown seedlings and transferred to Woody Plant Medium (WPM) containing 3% sucrose and 0.7% agar supplemented different plant growth regulators. The data were collected for callus fresh weight, callus dry weight and callus induction percentage. GC-MS analysis of essential oil constituents of P. atlantica subsp. kurdica callus was performed. Results showed that concentrations and combination of various plant growth regulators had significant effect on callus induction and callus weight. The high efficient callus formation was observed in the medium containing different concentration of 6-BAP individually. The lowest and highest percentage of callus induction were in the treatment of BA 2 mg/l with NAA 1mg/1 (40%) and 6BAP 1mg/l (85%), respectively. GC-MS separated eight kinds of substances in callus. Main compositions of callus were Bornyl acetate (9.18%), Spathulenol (5.89%) and Ledol (5.37%). Keywords: Auxin, callus, cytokinin, GC-MS, Pistacia atlantica subsp. Kurdica. Abbreviations: MS_Murashige and Skoog’s medium; BA_N6-benzyladenine; BAP_6-Benzylamino-purine, NAA_1-naphthylacetic acid; IAA_indole-3-acetic acid; TDZ_Thidiazuron; WPM_woody plant medium; PGR_plant growth regulators. Introduction Wild pistachio (Pistacia) is a genus of plants in tropical Anacardiaceae family. Three Pistacia species grow naturally in Iran, including P. vera Linnaeus, P. khinjuk and P. atlantica Desf. Large populations of P. atlantica subsp. kurdica trees growing in the wild across Kurdistan province of Iran. P. atlantica subsp. kurdica, with the local name of Baneh is used for medicine, food and industrial purposes. Baneh nuts are used by the natives after grinding and mixing with other nuts. Its gum is also used in the production of chewing gum (Daneshrad and Aynehchi, 1980). The biological effects of gum compounds including anti- atherogenic, hypoglycemic, anti-inflammatory, antipyretic, antifungal, antimicrobial, anti-viral, anti-insecticide and anticancer activities for Pistacia species has been established (Rezaei et al., 2011). Plant cell and tissue culture has been used as a strategy to improve trees through somaclonal variation, germplasm conservation, and genetic transformation and also for the production of secondary metabolites. Most research has focused on the species P. vera L. and less emphasis has been placed on some of the other important species of this genus. P. atlantica subsp. kurdica is the major source of a gum in Kurdistan, Iran and has not been known well to the world. P. atlantica kurdica is a sub-species of P.atlantica because of the presence of leaf rachis wing that narrower than the type of P. atlantica (Zohary, 1952). Most works on P. atlantica were focused on gum biological and antioxidant activities ((Rezaei et al., 2011). Regeneration of P. vera L. from seed or seedling tissues has been the most successful method to date (Yang and Ludders 1993, Parfitt and Almehdi 1994, Onay et al. 1995, 1996, Onay 2000). An efficient protocol for inducing direct shoot organogenesis from mature leaf explants of P. vera L. and the subsequent recovery of the pistachio plantlets has been reported (Tilkat and Onay 2009). There have also been several previous reports on plant regeneration from seedling explants of other wild pistachio species (Onay 2000, Tilkat et al. 2005). Onay (2000) produced embryogenic mass from kernels of mature fruits of P. atlantica cultured in liquid MS) media (Murashige and Skoog (1962), supplemented with 100 mg/l casein hydrolysate, 100 mg/l l-ascorbic acid, and 6BAP. Later matured somatic embryos germinated on the maturation medium without growth regulators and developed into plantlets.Plant tissue culture systems represent a potential renewable source of valuable medicinal compounds, flavors, fragrances, and colorants, which cannot be produced by microbial cells or chemical synthesis. Advances in biotechnology particularly methods for culturing plant cell cultures, should provide new means for the commercial processing of even rare plants and the chemicals they provide So far, there are no reports on the induction of callus in P. Plant Knowledge Journal Southern Cross Publishing Group ISSN: 2200-5390 Australia EISSN: 2200-5404