Rapid auxin-induced root growth inhibition requires the TIR and AFB auxin receptors.
We investigated the relation between auxin-induced gene expression and the rapid auxin-induced growth inhibition in Arabidopsis thaliana roots. The natural auxin indole-3-acetic acid (IAA) induced a strong activation of gene expression as visualized by the DR5rev::GFP reporter gene technique. This effect was specific for active auxins and was abolished in knockout mutants of the F-box auxin receptors. We measured the IAA-induced growth inhibition at high time resolution and show that the F-box auxin receptor mutants failed to display this effect. We conclude that the F-box auxin receptors are needed for the response. In hypocotyls, auxin induces an increase in elongation growth, and this effect has been earlier shown to be independent of the F-box receptors. Based on these findings, we discuss differences in the growth control modes in roots and shoots. We demonstrate that the rapid auxin-induced root growth inhibition, unlike the induction of growth in hypocotyls, requires the presence of the F-box auxin receptors.
Department of Plant Physiology, Biozentrum Flottbek of the University, Ohnhorststraße 18, 22609, Hamburg, Germany.
Katharina
K
Scheitz
Department of Plant Physiology, Biozentrum Flottbek of the University, Ohnhorststraße 18, 22609, Hamburg, Germany. h.luthen@botanik.uni-hamburg.de.
Hartwig
H
Lüthen
Department of Plant Physiology, Biozentrum Flottbek of the University, Ohnhorststraße 18, 22609, Hamburg, Germany.
Daniel
D
Schenck
D017360:Arabidopsis / Q000187:drug effects* / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D044783:F-Box Proteins / Q000235:genetics / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000494:pharmacology*; D009154:Mutation; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; D044783:F-Box Proteins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins; D011956:Receptors, Cell Surface; C501405:TIR1 protein, Arabidopsis; C046131:auxin receptor, plant
AFB; Auxin; Cell elongation; Receptor; Root growth; TIR1