Regeneration of plants from embryogenic callus, cell suspensions, protoplasts, and cryopreserved cell suspension cultures of napiergrass (Pennisetum purpureum Schum)

Plants of napiergrass or elephantgrass (Pennisetum purpureum Schum.) were regenerated from embryogenic calli derived from leaf and inflorescence segments, cell suspensions, protoplasts, and cryopreserved cell suspension cultures. The induction of somatic embryogenesis in segments of young leaves was found to be under developmental control, allowing a zone of cells competent for somatic embryogenesis to be mapped along the length of young leaves. Somatic embryogenesis was also initiated in segments of immature inflorescences. Factors important for the development of embryogenic suspension cultures were investigated. The starting callus tissues and gradual change of liquid medium were found to be critical for establishing embryogenic suspension cultures, which provided a critical source of protoplasts for the regeneration of plants. Plants regenerated from suspensions as well as protoplasts isolated from them grew to maturity in the field with normal morphology and chromosome numbers. Plants were also regenerated from cryopreserved cells after two and a half years of cryogenic storage, and established in soil.