Hormones and tomato seed germination

Y. Liu

Research output: Thesisinternal PhD, WU


Using GA- and ABA-deficient mutants, exogenous gibberellins (GAs), abscisic acid (ABA) and osmoticum, we studied the roles of GAs and ABA in the induction of cell cycle activities, internal free space formation and changes in water relations during seed development and imbibition in tomato. First of all, it was demonstrated that endogenous ABA plays an important role in induction of primary dormancy, prevention of viviparous germination and arresting cell cycle activities of the radicle-tip cells in G <sub><font size="-2">1</font></sub> phase upon maturation. Secondly, the flow cytometric analysis of seeds of the three genotypes upon imbibition in water, GA <sub><font size="-2">4+7</font></sub> or ABA solutions, revealed that GAs influence germination of intact seeds by acting upon the processes that precede cell cycle activation, or in other words, the weakening of the endosperm opposite radicle tip, induced by GAs, promotes cell growth and subsequently induces nuclear replication activity upon imbibition, while ABA affects growth by acting upon the processes that follow cell cycle activation. Studies with the controlled deterioration test (CD) show that, after osmotic priming, the advancement of germination of seeds, expressed as the ratio of 4C nuclei of radicle-tip calls, is positively related with the germination rate, and negatively related with the storability of the treated seeds. In addition, the determination of water relations illustrates that the absence of GAs and ABA during development and imbibition may alter water relations of both fruit and seed tissues, which certainly contributes to the mechanism preventing precocious and viviparous germination. Finally, it is concluded that exogenous GAs and ABA can relieve or strengthen the mechanical restraint imposed by the tissues surrounding the embryo, upon embryo water uptake, resulting in promoting or inhibiting germination by GAs and ABA respectively.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Karssen, C.M., Promotor
  • Luo, Z., Co-promotor, External person
  • Bino, R.J., Co-promotor, External person
  • Hilhorst, Henk, Co-promotor
Award date10 Jun 1996
Place of PublicationS.l.
Print ISBNs9789054855545
Publication statusPublished - 1996


  • germination
  • seed germination
  • seed dormancy
  • plant physiology
  • plant development
  • fruits
  • ripening
  • solanum lycopersicum
  • tomatoes
  • plant growth regulators


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