Journal Article

SCF(TIR1/AFB)-auxin signalling regulates PIN vacuolar trafficking and auxin fluxes during root gravitropism

Kleine-Vehn, Jürgen, Baster, Paweł, Kania, Urszula, Robert, Stéphanie, De Rybel, Bert, Friml, Jiří, Grunewald, Wim, Beeckman, Tom, Vanneste, Steffen

2013

Overview

The distribution of the phytohormone auxin regulates many aspects of plant development including growth response to gravity. Gravitropic root curvature involves coordinated and asymmetric cell elongation between the lower and upper side of the root, mediated by differential cellular auxin levels. The asymmetry in the auxin distribution is established and maintained by a spatio-temporal regulation of the PIN-FORMED (PIN) auxin transporter activity. We provide novel insights into the complex regulation of PIN abundance and activity during root gravitropism. We show that PIN2 turnover is differentially regulated on the upper and lower side of gravistimulated roots by distinct but partially overlapping auxin feedback mechanisms. In addition to regulating transcription and clathrin-mediated internalization, auxin also controls PIN abundance at the plasma membrane by promoting their vacuolar targeting and degradation. This effect of elevated auxin levels requires the activity of SKP-Cullin-F-box(TIR1/AFB) (SCF(TIR1/AFB))-dependent pathway. Importantly, also suboptimal auxin levels mediate PIN degradation utilizing the same signalling pathway. These feedback mechanisms are functionally important during gravitropic response and ensure fine-tuning of auxin fluxes for maintaining as well as terminating asymmetric growth.

• Subject: Arabidopsis - genetics / Arabidopsis - growth & development / Arabidopsis - metabolism / Arabidopsis Proteins - genetics / Arabidopsis Proteins - metabolism / Arabidopsis Proteins - physiology / F-Box Proteins - genetics / F-Box Proteins - metabolism / F-Box Proteins - physiology / Gene Expression Regulation, Plant / Gravitropism - genetics / Indoleacetic Acids - metabolism / Plant Roots - growth & development / Plant Roots - metabolism / Plant Roots - physiology / Plants, Genetically Modified / Protein Transport / Receptors, Cell Surface - genetics / Receptors, Cell Surface - metabolism / Receptors, Cell Surface - physiology / Signal Transduction - genetics / Signal Transduction - physiology / SKP Cullin F-Box Protein Ligases - genetics / SKP Cullin F-Box Protein Ligases - metabolism / SKP Cullin F-Box Protein Ligases - physiology / Vacuoles - metabolism