Somatic embryogenesis in macaw palm (Acrocomia aculeata) from zygotic embryos

Macaw palm (Acrocomia aculeata) is an oleaginous palm tree that is highly productive and adapted to semiarid ecosystems, which oil can be used to produce biodiesel. Such characteristics make macaw palm a potential crop to be used by farmers from semi-arid regions, but its propagation is still problematic. This paper reports the first description of somatic embryogenesis for macaw palm from zygotic embryos. The explants were cultured on Y3 medium and different combinations of plant growth regulators. After 60 days of culture, embryogenic callus were induced with 9 μM of 4-amino-3,5,6-trichloropicolonic acid (picloram) or 2,4-dichlorophenoxyacetic acid (2,4-D), combined or not with 1 μM N-phenyl N′1,2,3 thidiazol-5-yl urea (TDZ). Naphthoxy acetic acid (NOA) and 4-chlorophenoxyacetic acid (CPA) did not generate embryogenic callus. Somatic embryos were only obtained when embryogenic callus were induced with 9 μM picloram and then subcultured for 120 days on the same medium with 3.0 g l−1 activated charcoal. Anatomical sections showed that somatic embryos had a typical protoderm, procambial strands and an apical meristem. When transferred to Y3 medium +3.0 g l−1 activated charcoal, without growth regulators, half of the somatic embryos germinated, but only a few completed the germination.