SOMATIC EMBRYOGENESIS IN CITRUS FROM STYLES CULTURE

Styles (including the stigma) of Citrus aurantium L. (cvs. 'AA 12', 'AA 30' and 'AA 31'), C. deliciosa Tenore (cvs. 'Avana' and 'Tardivo di Ciaculli'), C. paradisi Macf. (cvs. 'Marsh seedless' and 'Star Ruby') and C. sinensis (L.) Osb. (cvs. 'Bonanza', 'Brasiliano 92', 'Sanguinello' and 'Valencia') were cultured for induction of somatic embryogenesis. Explants were excised from flower buds which were collected during full bloom, and cultured on Murashige and Skoog (MS) basal medium supplemented with 146 mM sucrose, 500 mg/l malt extract and 13.3 mu M 6-benzylaminopurine (BAP) as well as the same medium without BAP. Callus development was observed from the style base 4 weeks after treatment initiation, and embryogenesis occurred 2-3 months later. Embryogenesis has been induced from the style-derived callus of all the cultivars tested except for the cultivars 'Avana' and 'Star Ruby'. The best results for callus growth and embryo regeneration was obtained from explants of 'Brasiliano 92' cultured on medium containing BAP. Somatic embryos were isolated from callus and placed on MS medium supplemented with 146 mM sucrose, 500 mg/l malt extract and 0.27 mu M alpha-naphthaleneacetic acid (NAA) where they formed entire plants. Two months later plants were successfully established in soil.