Preventing leaf identity theft with hormones.
Genetic analysis of plant development has begun to demonstrate the importance of hormone synthesis and transport in regulating morphogenesis. In the case of leaf development, for example, auxin pooling determines where a primordium will emerge and leads to the activation of transcription factors, which determine leaf identities by modulating abscisic acid (ABA) and gibberellic acid (GA) concentrations. Signal transduction studies suggest that negative regulation of transcription factors through protein turnover is commonly used as a mechanism of hormone action. Together, these findings suggest that auxin might degrade a repressor that allows the activation of genes that modulate ABA/GA ratios in emerging leaves. With our increased understanding of the molecular basis of hormone signaling, it is becoming possible to overlay important regulators onto signaling modules that determine morphological outputs.
Lumba
Shelley
S
Department of Botany, University of Toronto, Toronto, Ontario M5S 3B2, Canada.
McCourt
Peter
P
D000040:Abscisic Acid / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D063245:Plant Development; D010937:Plant Growth Regulators / Q000378:metabolism / Q000502:physiology*; D018515:Plant Leaves / Q000254:growth & development*; D015398:Signal Transduction / Q000502:physiology*
D005875:Gibberellins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D000040:Abscisic Acid