title: Polyamines, IAA and ABA during germination in two recalcitrant seeds: Araucaria angustifolia (Gymnosperm) and Ocotea odorifera (Angiosperm).
abstract: OBJECTIVE
  Plant growth regulators play an important role in seed germination. However, much of the current knowledge about their function during seed germination was obtained using orthodox seeds as model systems, and there is a paucity of information about the role of plant growth regulators during germination of recalcitrant seeds. In the present work, two endangered woody species with recalcitrant seeds, Araucaria angustifolia (Gymnosperm) and Ocotea odorifera (Angiosperm), native to the Atlantic Rain Forest, Brazil, were used to study the mobilization of polyamines (PAs), indole-acetic acid (IAA) and abscisic acid (ABA) during seed germination.
  
  
  METHODS
  Data were sampled from embryos of O. odorifera and embryos and megagametophytes of A. angustifolia throughout the germination process. Biochemical analyses were carried out in HPLC.
  
  
  RESULTS
  During seed germination, an increase in the (Spd + Spm) : Put ratio was recorded in embryos in both species. An increase in IAA and PA levels was also observed during seed germination in both embryos, while ABA levels showed a decrease in O. odorifera and an increase in A. angustifolia embryos throughout the period studied.
  
  
  CONCLUSIONS
  The (Spd + Spm) : Put ratio could be used as a marker for germination completion. The increase in IAA levels, prior to germination, could be associated with variations in PA content. The ABA mobilization observed in the embryos could represent a greater resistance to this hormone in recalcitrant seeds, in comparison to orthodox seeds, opening a new perspective for studies on the effects of this regulator in recalcitrant seeds. The gymnosperm seed, though without a connective tissue between megagametophyte and embryo, seems to be able to maintain communication between the tissues, based on the likely transport of plant growth regulators.
authors.affiliation: Instituto de Biociências, Universidade de São Paulo, Rua do Matão 05422-970 São Paulo, Brazil.
authors.forename: Fernanda P
authors.initials: FP
authors.lastname: Pieruzzi
authors.forename: Leonardo L C
authors.initials: LL
authors.lastname: Dias
authors.forename: Tiago S
authors.initials: TS
authors.lastname: Balbuena
authors.forename: Claudete
authors.initials: C
authors.lastname: Santa-Catarina
authors.forename: André L W
authors.initials: AL
authors.lastname: dos Santos
authors.forename: Eny I S
authors.initials: EI
authors.lastname: Floh
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D001938:Brazil; D056727:Endangered Species; D018525:Germination / Q000502:physiology*; D007210:Indoleacetic Acids / Q000378:metabolism*; D027444:Ocotea / Q000254:growth & development / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism; D012639:Seeds / Q000254:growth & development / Q000378:metabolism*; D064028:Tracheophyta / Q000254:growth & development / Q000378:metabolism*
chemical_list: D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; C030737:indoleacetic acid; D000040:Abscisic Acid