Somatic Embryogenesis in Multiple Purpose Tree (Jojoba; Arizona Cultivar) by Direct and Indirect Techniques

Although Jojoba [Simmondsia chinensis] belongs to the Simmondsiaceae family, which is an evergreen perennial and salt tolerant shrub but developing of this plant in horticultural farming system by seed is not easy except by producing hybrid seeds with very high costs. In order to produce the vegetative seedlings, the indirect somatic embryogenesis (ISE) and direct somatic embryogenesis (DSE) from jojoba leaf explants were investigated. In indirect trial the leaf explants were cultured on Murashige and Skoog (MS) medium for one month and then were supplemented with various concentrations of plant growth regulators such as 2,4-D (0.45, 2.26 and 4.52 μM) and salicylic acid (SA: 0, 10, 100, 500 μM). After 30 days calli begun to grow, then were subcultured on the same medium. Results showed high callogenesis and somaclonal variation on 4.52 μM of 2,4-D plus 100 μM of SA supplemented medium,therefore, for callus production from jojoba leaf explants, it is recommended to use the treatment of 2.26 μM 2,4-D and 10 μM of SA for embryo formation on maturation medium. The results of direct somatic embryogenesis of jojoba leaf explants on ½MS medium with all treatments showed the effects of thidiazuron (TDZ) and acetyl salicylic acid (ASA) on embryos production directly from leaf wound surfaces without an intervening callus phase. The results also indicated that both TDZ and ASA have significant effects on number of embryos produced in 10 μM of ASA plus 50 μM of TDZ as the best treatment.