IN VITRO REGENERATION AND SOMATIC EMBRYOGENESIS IN CITRUS

Plant regeneration through somatic embryogenesis was investigated in Washington navel orange, Satsuma mandarin, Lemon, Variegated lemon, Lime, Citron, Pummelo, Rough lemon , Sour orange , Volkamer lime and Rangpur lime using stigma, style and ovary as explants. Explants were cultured on Murashige and Skoog( MS )medium supplemented with50 gl-1 sucrose, 500 mgl-1 malt extract and 3 mgl-1 Benzyl adinen (BA). Two months later, somatic embryos were induced from embryogenic callus. The percentage of embryo formation and number of embryo germinated depended on the explants type and genotype. Best results were obtained when stigma explants of variegated lemon and Citron were used. After ten months, somatic embryos developed into plantlets at a frequency ranged from13.3% for Lime to 66.7 % for Lemon. Virus presence was tested by ELISA and RT-PCR . The obtained results indicated that the plantlets regenerated through somatic embryogenesis were CTV-free. RAPD analysis was used to asses the genetic stability of obtained plantlets as compared to the mother plants. Results indicated that most plantlets were belonging to the respective mother plants andthe polymorphism percentage was genotype and explant- dependant.Abbreviations: BA – Benzyladenine; CTV – citrus tristiza virus; TCL – Thin cell layer ; CPsV – citrus pserosis virus; GA3 – Gibrillic acid.