Lateral relocation of auxin efflux regulator PIN3 mediates tropism in Arabidopsis Journal Article

Author(s): Friml, Jiří; Wiśniewska, Justyna; Benková, Eva; Mendgen, Kurt; Palme, Klaus
Article Title: Lateral relocation of auxin efflux regulator PIN3 mediates tropism in Arabidopsis
Abstract: Long-standing models propose that plant growth responses to light or gravity are mediated by asymmetric distribution of the phytohormone auxin. Physiological studies implicated a specific transport system that relocates auxin laterally, thereby effecting differential growth; however, neither the molecular components of this system nor the cellular mechanism of auxin redistribution on light or gravity perception have been identified. Here, we show that auxin accumulates asymmetrically during differential growth in an efflux-dependent manner. Mutations in the Arabidopsis gene PIN3, a regulator of auxin efflux, alter differential growth. PIN3 is expressed in gravity-sensing tissues, with PIN3 protein accumulating predominantly at the lateral cell surface. PIN3 localizes to the plasma membrane and to vesicles that cycle in an actin-dependent manner. In the root columella, PIN3 is positioned symmetrically at the plasma membrane but rapidly relocalizes laterally on gravity stimulation. Our data indicate that PIN3 is a component of the lateral auxin transport system regulating tropic growth. In addition, actin-dependent relocalization of PIN3 in response to gravity provides a mechanism for redirecting auxin flux to trigger asymmetric growth.
Keywords: Mutation; Molecular Sequence Data; Phenotype; Protein Transport; Gene Expression Regulation, Plant; Genes, Plant; Arabidopsis; Arabidopsis Proteins; Indoleacetic Acids; Hypocotyl; Exons; Gravitation; Introns; Physical Chromosome Mapping
Journal Title: Nature
Volume: 415
Issue 6873
ISSN: 0028-0836
Publisher: Nature Publishing Group  
Date Published: 2002-02-14
Start Page: 806
End Page: 809
DOI: 10.1038/415806a
Open access: no