Capacity for somatic embryogenesis of adult oil palm genitors (Elaeis guineensis, var. Pisifera) from immature leaf tissues

Abstract Admittedly, Pisifera genotypes are less responsive to somatic embryogenesis than other genotypes, such as inter- or intra-specific oil palm hybrids. However, clonal propagation of Pisifera plants can be useful for increasing the number of male parents to cross with the Dura variety for mass producing the Tenera commercial varieties. The capacity for somatic embryogenesis (SE) of Brazilian Pisifera genitors was therefore investigated using achlorophyllous leaf explants from four field growing genotypes (A251424, A251427, A251512, A251513). A Murashige & Skoog (MS) medium supplemented with 0.5 gL−1 glutamine, 0.5 gL−1 casein, 2.5 gL−1 activated charcoal, 450 µM Picloram and 2.5 gL−1 Phytagel was used for the induction. A251424 showed the higher capacity for SE induction with 45.8% of callus formation compared to 11.3% for A251427, 7.7% for A251513 and 0.6% for A251512. The materials remained in these conditions for up to 360 days, being subcultured every 150 days before transfer for 90 days onto the multiplication medium (MM), containing 40 μM Picloram and 10 μM 2-isopentenyladenine (2iP). Callus fresh biomass increased approximately fivefold in these MM conditions. The calli were then placed onto the somatic embryo differentiation medium (DM), composed of 12.3 μM 2iP and 0.54 μM naphthalene acetic acid (NAA) until the formation of the first somatic embryo clusters. These were transferred to the somatic embryo regeneration medium (RM) totally lacking growth regulators but with 2.5 gL−1 activated charcoal. Histocytological observations indicated that cells showing the greater concentration of starch granules could be considered as embryogenic with the higher capacity for SE. To our knowledge, this is the first report on the successful use of immature leaf explants for producing SE from Pisifera genitors of Elaeis guineensis.