Induction of proembryos in liquid culture increases the efficiency of plant regeneration from Alstroemeria calli

There have been some reports of the regeneration of Alstroemeria plants in tissue culture, but progress toward micropropagation and genetic transformation of this genus has been slow. In this study, we developed an efficient procedure for plant regeneration from calli of Alstroemeria by somatic embryogenesis. Suspension cells were maintained in Murashige and Skoog's (MS) medium supplemented with 1 mg/l picloram and then used for either solid or liquid culture. Friable embryogenic calli formed in liquid half-strength MS medium supplemented with 0.5 mg/l naphthaleneacetic acid (NAA) and 0.5 mg/l benzyladenine (BA). The friable calli developed proembryos after transfer to solidified half-strength MS medium without growth regulators. Plantlets developed from the proembryos directly or via secondary embryos after they were cultured on solidified half-strength MS medium supplemented with 0-2 mg/l BA. In contrast, organogenesis occurred at high frequency on solidified half-strength MS medium supplemented with 0.5 or I mg/l NAA and 0.5 mg/l kinetin. About 90 regenerated plantlets were obtained from I g of callus after 8 months of culture by organogenesis, whereas about 450 regenerated plantlets were developed from the same amount of callus after 3 months of culture by embryogenesis. Thus, the system for regeneration of plants via somatic embryogenesis was better than that via organogenesis in terms of the reduced culture time and more regenerants. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.