Seed dormancy and ABA signaling: the breakthrough goes on.
The seed is an important organ of higher plants regarding plant survival and species dispersion. The transition between seed dormancy and germination represents a critical stage in the plant life cycle and it is an important ecological and commercial trait. A dynamic balance of synthesis and catabolism of two antagonistic hormones, abscisic acid (ABA) and giberellins (GAs), controls the equilibrium between seed dormancy and germination. Embryonic ABA plays a central role in induction and maintenance of seed dormancy, and also inhibits the transition from embryonic to germination growth. Therefore, the ABA metabolism must be highly regulated at both temporal and spatial levels during phase of dessication tolerance. On the other hand, the ABA levels do not depend exclusively on the seeds because sometimes it becomes a strong sink and imports it from the roots and rhizosphere through the xylem and/or phloem. All theses events are discussed in depth here. Likewise, the role of some recently characterized genes belonging to seeds of woody species and related to ABA signaling, are also included. Finally, although four possible ABA receptors have been reported, not much is known about how they mediate ABA signalling transduction. However, new publications seem to shown that almost all these receptors lack several properties to consider them as such.
Rodríguez-Gacio
María del Carmen
Mdel C
Department of Plant Physiology, University of Santiago de Compostela, A Coruña, Spain.
Matilla-Vázquez
Miguel A
MA
Matilla
Angel J
AJ
D000040:Abscisic Acid / Q000235:genetics / Q000378:metabolism*; D017343:Genes, Plant; D018525:Germination / Q000235:genetics / Q000502:physiology*; D019684:Magnoliopsida / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D010937:Plant Growth Regulators / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018514:Plant Structures; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012639:Seeds / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D015398:Signal Transduction
D010937:Plant Growth Regulators; D010940:Plant Proteins; D016601:RNA-Binding Proteins; C415086:p67 protein, Raphanus sativus; D000040:Abscisic Acid