Somatic embryogenesis from zygotic embryos and shoot-tips of the Chilean tree Gomortega keule

Abstract

The endangered Chilean tree Gomortega keule (Mol.) Baillon produces edible fruit, making it a potential crop. However, its cultivation from seed or cuttings is extremely difficult. This paper reports the induction of somatic embryogenesis and the initiation of liquid cultures in this species. Callus was induced from zygotic embryos and field-collected shoots. Somatic embryogenesis on zygotic embryos occurred at a low frequency. Induction of somatic embryogenesis was accomplished on micropropagated shoots after 6.5 months on semi-solid Murashige and Skoog (MS) medium with 30 g/l sucrose, 1.0 mg/l 2,4-dichlorophenoxyacetic acid and 1.0 mg/l 6-(γ,γ-dimethylallylamino) purine (2iP). Liquid cultures of compact callus and small aggregates were obtained and showed optimum proliferation in MS medium with 20 g/l sucrose, 0.01 mg/l α-naphthaleneacetic acid and 0.1 mg/l 2iP. The proliferation of friable embryogenic callus was observed in liquid medium and will allow the propagation of selected genotypes of this tree on a large scale. Genetic variation in two embryogenic genotypes cultured in vitro was not detected in an assessment using microsatellites; this approach is suitable for tracing genotypes.