Culture of triploid tissue from the endosperm of an endangered Chilean tree speciesGomortega keule

The endangered Chilean tree species Gomortega keule (Mol.) Baillon produces an edible fruit, but is not cultivated at present. Recent advances in micropropagation may allow the further development of this species as a fruit crop. Triploid plants have been regenerated from the endosperm of seed of a number of species. This is the first report on in vitro culture of the seed endosperm of G. keule in order to obtain triploid plants. Callus was formed from endosperm after 1.5 months on 1.0× Murashige and Skoog medium supplemented with 2,4-dichlorophenoxyacetic acid and 6-(γ,γ-dimethylallylamino) purine. Shoot primordia developed and produced shoots that could be cultured on Rugini medium containing 0.1 mg l–1 α-naphthaleneacetic acid and 1 mg l–1 6-benzyladenine. Shoot primordia cultured on Rugini medium containing 2 g l–1 activated charcoal produced longer shoots and longer leaves compared to diploid genotypes. Flow cytometry and chromosome observations indicated that the callus tissue and plantlets derived from the seed endosperm were triploid. Endosperm culture represents a feasible method to regenerate triploid plantlets of this tree species within 18 months. Such material may be of value for the genetic improvement and future development of G. keule as a commercial fruit tree species.