Somatic embryogenesis in macaw palm (Acrocomia aculeata) from zygotic embryos Elisa Ferreira Moura a, *, Se ´ rgio Yoshimitsu Motoike a , Marı ´lia Contin Ventrella b , Adauto Quirino de Sa ´ Ju ´ nior a , Mychelle Carvalho a a Laborato ´rio de Cultura de Tecidos e Ce ´lulas Vegetais, Departamento de Fitotecnia, Universidade Federal de Vic ¸osa, Av. Ph Rholfs s/n, 36570-000 Vic ¸osa, MG, Brazil b Laborato ´rio de Anatomia Vegetal, Departamento de Biologia Vegetal, Universidade Federal de Vic ¸osa, Av. Ph Rholfs s/n, 36570-000 Vic ¸osa, MG, Brazil 1. Introduction With the world’s increasing demand for energy and unques- tionable environmental concerns in using fossil fuel, the search for new sources of energy becomes essential. Adding to this, reduction in the world oil reserves and international conflicts have contributed to an increase in fuel prices never reached before. Facing this reality, the use of biodiesel, a plant and animal oils derivative, is considered a fine alternative to replace petroleum-derived fuels due to its renewable and biodegradable character and its low emission profile. Among several plant species capable of producing crude oil, a raw material for biodiesel production, palms are considered the most promising species. Macaw palm (Acrocomia aculeata (Jacq.) Lodd. ex Martius) is a palm widely distributed in the American continent including Mexico, Antilles, Brazil, Argentina, Uruguay and Paraguay. Different from oil palm (Elaeis guineensis), which requires a hot humid tropical environment to grow, macaw palm is adapted to different environments, including cooler subtropical and drier semiarid ecosystem (Arkcoll, 1990). This palm is highly productive and its fruits can generate more than 5000 kg of oil per hectare (Tickel, 2000). Also, a significant amount of a high quality charcoal can be produced from its endocarp (Silva et al., 1986). However, macaw palm plantations in Brazil and in many places in the world are still in their primary stage. The macaw palm fruit exploitation occurs mostly by gathering in large natural popula- tions (Motta et al., 2002). Its commercial exploitation depends on the development of technology, which includes the selection of elite clones and its propagation. Superior genotypes can be selected directly among plants of natural populations, however, it is impossible to propagate macaw palm by conventional vegetative propagation techni- ques, since they do not have axillary meristem. Thus, somatic embryogenesis can be an attractive means to propagate macaw palm vegetatively. Somatic embryogenesis is the process by which single or multiple cultured cells differentiate to form somatic embryos. Somatic embryos resemble sexual embryos and develop similarly, since they go through all stages of embryogenesis to yield an embryo-like structure, which has both a root and a shoot meristems. They are genetically identical to Scientia Horticulturae 119 (2009) 447–454 ARTICLE INFO Article history: Received 28 February 2008 Received in revised form 19 August 2008 Accepted 23 August 2008 Keywords: Histological study Oleaginous plant Tissue culture ABSTRACT 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 Y 3 medium and different combinations of plant growth regulators. After 60 days of culture, embryogenic callus were induced with 9 mM of 4-amino-3,5,6- trichloropicolonic acid (picloram) or 2,4-dichlorophenoxyacetic acid (2,4-D), combined or not with 1 mM N-phenyl N 0 1,2,3 thidiazol-5-yl urea (TDZ). Naphthoxy acetic acid (NOA) and 4-chlorophenox- yacetic acid (CPA) did not generate embryogenic callus. Somatic embryos were only obtained when embryogenic callus were induced with 9 mM 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 Y 3 medium +3.0 g l 1 activated charcoal, without growth regulators, half of the somatic embryos germinated, but only a few completed the germination. ß 2008 Elsevier B.V. All rights reserved. * Corresponding author at: Embrapa Amazo ˆ nia Oriental, Trav. Ene ´ as Pinheiro s/n, Marco, 66095-100 Bele ´ m, Para ´ , Brazil. Tel.: +55 9132041158; fax: +55 9132296469. E-mail address: ferrmoura@hotmail.com (E.F. Moura). Contents lists available at ScienceDirect Scientia Horticulturae journal homepage: www.elsevier.com/locate/scihorti 0304-4238/$ – see front matter ß 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.scienta.2008.08.033