Ontogênese, diversidade genotípica de respostas e análise proteômica de etapas envolvidas na embriogênese somática de dendezeiro (Elaeis guineensis JACQ.)

Abstract

This study aims to evaluate genotypic responses during somatic embryogenesis from zygotic embryos of oil palm (Elaeis guineensis Jacq.) as well as to evaluate the ontogeny and identify proteins differentially expressed during different stages of embryogenesis. Zygotic embryos were used in nine genotypes: C2001, C2328, C2301, C3701, CM1115, C7201, C2528, C2501 and CN1637. Initially, the zygotic embryos were inoculated in culture medium for callus induction (450 μM Picloram), with subcultures every 30 days. After 150 days, callus were transferred to two culture media in orderto differentiation and maturation of somatic embryos: MTD -1 (0.6μM NAA and 12.3 μM 2-iP) and MTD-2 (40 μM Picloram). After 90 days, the callus with somatic embryos were transferred to regeneration medium devoid of growth regulators. At all stages the explants were kept in growth room with temperature 25 ± 2° C and dark conditions. The analysis was performed anatomical mold during the embryogenic process. Since the proteomic samplewere collected from zygotic embryos (E1), with swollen explants 14 days (E2) in induction medium, primary callus (E3) and callus pro-embryogenic (E4). It was found that the genotypes have different morphogenic responses in vitro. In the induction phase, genotypes C2501, C2001, C7201, C2528, C2328 and C3701 showed better results in the formation of embryogenic callus, with values between 90 and 100%. After 90 days of regeneration, the genotypes that showed the best results in the formation and regeneration of somatic embryos were C2328 and CM1115. The anatomical analysis allowed notice to 14 days in induction medium the formation of the first divisions procambium cells and perivasculary. This region has progressed to the formation of meristematic masses after 21 days, indicating their procambial and perivasculary. Primary callus appeared after 45 days of culture, followed by progression to embryogenic callus at 90 days. The formation of proembrions from meristematic cells, occurred after 135 of cultivation. The proembrions presented them selves isolated from the tissue of origin, by thickening the cell wall, indicating their unicellular origin. When transferred to the maturation phase in culture MTD -1 (0.6 μM NAA and 12.3 μM 2-iP) and MTD-2 (40 μM picloram), we observed the regeneration of somatic embryos at different stages development (globular-torpedo). The embryos were differentiated protoderm, strands of procambium and plumule. They were then transferred to culture medium free of growth regulators (regeneration phase plants), which was observed in the conversion of embryos into plants. The accumulation of starch during the process of somatic embryogenesis was concentrated near the centers of intense cell division, and the cortex of primary and embryogenic callus. However, in different stages of somatic embryos was not observed the accumulation of starch. Already proteomic analysis has identified proteins involved in the acquisition of embryogenic competence. Proteins were categorized into seven groups according to their biological function as well as by participating in different metabolic pathways: 1) proteins expressed in stress conditions, 2) proteins involved in cell cycle, 3) proteins involved in the accumulation of starch, 4) energy metabolism proteins, 5) protein of nitrogen metabolism, 6) processing of proteins and 7) proteins of zygotic embryo. Knowledge of the in vitro reconstitution of the events, physiological, genotypic ontogenetic and biochemical factors involved in somatic embryogenesis in E. guineensis enable a greater understanding of the kind of cloning, whether for the production of seedlings in scale, is to accelerate breeding programs of culture.