Repetitive somatic embryogenesis in Medicago truncatula ssp. Narbonensis and M-truncatula Gaertn cv. Jemalong

Medicago truncatula ssp Narbonensis and four genotypes of hi. truncatula Ga ertn cv. Jemalong were rested for their somatic embryogenesis potential usi ng a two-step protocol. In the first step, embryogenic callus was induced i n folioles isolated from shoots grown in vitro and cultured on Murashige an d Skoog (MS) medium supplemented with 2,4-dichlorophenoxyacetic acid and ze atin. In the second step, somatic embryos were allowed to develop from the induced callus in MS growth-regulator-free medium. Individual somatic embry os were then isolated and transferred again to growth regulator free medium where they formed secondary somatic embryos in repetitive cycles. Conversi on of somatic embryos into plantlets was achieved by isolating late-torpedo -phase somatic embryos with distinct cotyledons and reculturing them onto M S growth regulator free medium, The system of repetitive somatic embryogene sis in M. truncatula described here represents a permanent source of embryo genic material that can be used for the genetic modification of this specie s.