Somatic embryogenesis in sisal (Agave sisalana Perr. ex. Engelm)

A protocol has been developed for somatic embryogenesis and plant regeneration of sisal (Agave sisalana Perr. ex. Engelm). Embryogenic callus cultures were initiated from young shoots raised in vitro from the stem portion of the bulbil on medium supplemented with 1-2 mg l(-1) kinetin (KN) and 0.2-0.5 mg l(-1) alpha-naphthaleneacetic acid plus KN or 1-1.5 mg l(-1) benzylaminopurine (BAP) or 0.25-0.5 mg l(-1) 2,4-dichlorophenoxyacetic acid plus BAP or 0.5-1.0 mg l(-1) KN. Embryos at various developmental stages (globular-, heart- or torpedo-shaped) produced mature and germinating embryos on being transferred to a new medium containing 0-0.25 mg l(-1) KN. After 28 days, a maximum of 76% germinated embryos was obtained on a medium supplemented with 0.1 mg l(-1) KN. The capacity for embryogenesis remained constant in the callus upon subculturing on the same medium for more than 48 months. Histological observations showed a distinct multicellular origin for most of the somatic embryos as they developed from epidermal, sub-epidermal and inside callus cells, while a few of them originated from a superficial callus cell. Plantlets regenerated from embryos were transferred to the field where their survival rate was 100%.