title: Control of macaw palm seed germination by the gibberellin/abscisic acid balance.
abstract: The hormonal mechanisms involved in palm seed germination are not fully understood. To better understand how germination is regulated in Arecaceae, we used macaw palm (Acrocomia aculeata (Jacq.) Lodd. Ex Mart.) seed as a model. Endogenous hormone concentrations, tocopherol and tocotrienol and lipid peroxidation during germination were studied separately in the embryo and endosperm. Evaluations were performed in dry (D), imbibed (I), germinated (G) and non-germinated (NG) seeds treated (+GA3 ) or not treated (control) with gibberellins (GA). With GA3 treatment, seeds germinated faster and to a higher percentage than control seeds. The +GA3 treatment increased total bioactive GA in the embryo during germination relative to the control. Abscisic acid (ABA) concentrations decreased gradually from D to G in both tissues. Embryos of G seeds had a lower ABA content than NG seeds in both treatments. The GA/ABA ratio in the embryo was significantly higher in G than NG seeds. The +GA3 treatment did not significantly affect the GA/ABA ratio in either treatment. Cytokinin content increased from dry to germinated seeds. Jasmonic acid (JA) increased and 1-aminocyclopropane-1-carboylic acid (ACC) decreased after imbibition. In addition, α-tocopherol and α-tocotrienol decreased, while lipid peroxidation increased in the embryo during germination. We conclude that germination in macaw palm seed involves reductions in ABA content and, consequently, increased GA/ABA in the embryo. Furthermore, the imbibition process generates oxidative stress (as observed by changes in vitamin E and MDA).
authors.affiliation: Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: E M
authors.initials: EM
authors.lastname: Bicalho
authors.affiliation: Departamento de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Pintó-Marijuan
authors.affiliation: Departamento de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Morales
authors.affiliation: Departamento de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Müller
authors.affiliation: Departamento de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Munné-Bosch
authors.affiliation: Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Q S
authors.initials: QS
authors.lastname: Garcia
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D028023:Arecaceae / Q000502:physiology*; D003517:Cyclopentanes / Q000378:metabolism; D003583:Cytokinins / Q000378:metabolism; D018525:Germination / Q000502:physiology; D005875:Gibberellins / Q000378:metabolism*; D015227:Lipid Peroxidation; D054883:Oxylipins / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism*; D012639:Seeds / Q000502:physiology; D024508:Tocotrienols / Q000378:metabolism; D024502:alpha-Tocopherol / Q000378:metabolism
chemical_list: D003517:Cyclopentanes; D003583:Cytokinins; D005875:Gibberellins; D054883:Oxylipins; D010937:Plant Growth Regulators; D024508:Tocotrienols; C011006:jasmonic acid; D000040:Abscisic Acid; C082032:tocotrienol, alpha; D024502:alpha-Tocopherol
keywords: Abscisic acid; auxin; cytokinin; gibberellin; lipid peroxidation; tocopherol