Explant origin and culture media factors drive the somatic embryogenesis response in Acrocomia aculeata (Jacq.) Lodd. ex Mart., an emerging oil crop in the tropics

The explant origin and the factors in the culture medium are responsible for the response to somatic embryogenesis in most plant species, including palms. Acrocomia aculeata is a neotropical palm currently undergoing domestication due to its sustainability and profitability as an alternative oil crop. The attainment of productive cultivars of this palm may be speed up by somatic embryogenesis. Thus, this study sought to refine an existing somatic embryogenesis cloning protocol for A. aculeata and to investigate the possible genetic influence on the in vitro propagation response, using zygotic embryos from 19 matrices or open-pollinated families. The embryos were inoculated in modified induction media. The following characteristics were evaluated in this phase: swollen embryos, percentage of zygotic embryos that formed callus, embryogenic calli and oxidation. Afterwards the resulting pro embryogenic masses were subsequently cultivated in modified multiplication, maturation and gemination media. In those phases the open-pollinated families' response was measured by the growth of their embryogenic mass and the quantity of regenerated and germinated somatic embryos. The refined micropropagation protocol was successful in establishing embryogenic lines and maintaining their cyclic multiplication for a long period; all without the loss of their potential to maturate and regenerate somatic embryos. In general, the multiplication of pro embryogenic masses was effective even in the lowest dose of Picloram (18 μM). The addition of activated charcoal in the medium favored the maturation of somatic embryos. Plantlets regeneration, although defective in some lineages, was promoted by GA3 (0.55 μM). The zygotic embryos' responsiveness to somatic embryogenesis varied according to their matrices, indicating that if micropropagation is to be used as a mass propagation technique for the species, the explant́s genotype must be considered.