Somatic embryogenesis from sepal explants in Sapindus trifoliatus, a plant valuable in herbal soap industry

Somatic embryogenesis and complete plant regeneration were achieved in callus cultures derived from sepal explants of Sapindus trifoliatus, an important and valuable tree used in saponin and herbal soap industry. Embryogenic calli were induced on MS medium containing 5.0 mg l−1 2, 4-D and 0.1 mg l−1 Kin. Explant orientation markedly influenced on somatic embryogenesis. The calli induced on medium supplemented with 2, 4-D and Kin showed the formation of whitish or greenish nodular embryogenic structure on MS basal medium containing l-glutamine. These nodular embryogenic structures gave rise to somatic embryos or secondary nodular embryogenic structures or both. Nodular embryogenic structures separated from embryogenic calli and transferred to MS medium containing 200 mg l−1l-glutamine produced maximum number of globular, heart and cotyledonary stage somatic embryos. Histological studies have revealed the development of different stages of somatic embryos from nodular embryogenic structure. The embryogenic competence of the culture could be maintained by recurrent production of nodular embryogenic structures and somatic embryos. Somatic embryos were germinated and converted into plantlet on MS basal medium containing 2% sucrose. Plants propagated in vitro from somatic embryos were hardened and successfully established in field condition. The improved and promising regeneration method reported here for the S. trifoliatus may be valuable in herbal soap industry.