ABSTRACT
In-vitro induction of somatic embryogenesis and regeneration ability of jojoba [Simmondsia chinensis [Link] Schneider] plant were investigated using two different types of explants, i.e., immature zygotic embryos and leaf disks, and different culture media. Compact embryogenic callus was induced on Murashige and Skoog [MS] medium supplemented with various concentrations of 2, 4-dichlorophenoxyacetic acid [2, 4-D] and sucrose. Embryogenic callus was developed from immature zygotic embryos on MS medium containing 1.0 mg/l 2, 4-D, 0.1 mg/l 6-benzyl aminopurine [BA] and 4% sucrose. Induced calli were subcultured on MS medium supplemented with [4% or 6%] sucrose and 0.1, 0.5 and 1.0 mM kinetin for plant regeneration. Somatic embryos at the globular, heart-shaped, torpedo, and cotyledonary stages were developed. Embryogenic callus and hence different stages of somatic embryos were developed from leaf segments on MS medium supplemented with 3%, 4% or 6% sucrose, 1.0 mg/l 2, 4-D and 0, 0.1, 0.5 or 1.0 mg/l BA. Leaf-derived embryogenic calli did not mature on any of the maturation/germination media examined even after 4 weeks of culture. Random amplified polymorphic DNA [RAPD] technique was used to investigate the patterns and distribution of genetic variability in natural field-grown cuttings of jojoba plants. Five oligonucleotide primers were used to screen five randomly selected jojoba samples for analysis. Total DNA extracted from field-grown cutting leaves was used as template in the PCR reaction. The five primers used showed a highly polymorphic nature of the studied plants. It is concluded that jojoba plants in the natural habitate of Egypt may belong to different genotypes, none of them could differentiate to complete plantlets by tissue culture