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Gravitropism of Arabidopsis thaliana Roots Requires the Polarization of PIN2 toward the Root Tip in Meristematic Cortical Cells
Plant Cell (2010)
  • Abidur Rahman
  • Maho Takahashi
  • Kyohei Shibasaki
  • Shuang Wu
  • Takehito Inaba
  • Seiji Tsurumi
  • Tobias Baskin, University of Massachusetts - Amherst
Abstract

In the root, the transport of auxin from the tip to the elongation zone, referred to here as shootward, governs gravitropic bending. Shootward polar auxin transport, and hence gravitropism, depends on the polar deployment of the PIN-FORMED auxin efflux carrier PIN2. In Arabidopsis thaliana, PIN2 has the expected shootward localization in epidermis and lateral root cap; however, this carrier is localized toward the root tip (rootward) in cortical cells of the meristem, a deployment whose function is enigmatic. We use pharmacological and genetic tools to cause a shootward relocation of PIN2 in meristematic cortical cells without detectably altering PIN2 polarization in other cell types or PIN1 polarization. This relocation of cortical PIN2 was negatively regulated by the membrane trafficking factor GNOM and by the regulatory A1 subunit of type 2-A protein phosphatase (PP2AA1) but did not require the PINOID protein kinase. When GNOM was inhibited, PINOID abundance increased and PP2AA1 was partially immobilized, indicating both proteins are subject to GNOM-dependent regulation. Shootward PIN2 specifically in the cortex was accompanied by enhanced shootward polar auxin transport and by diminished gravitropism. These results demonstrate that auxin flow in the root cortex is important for optimal gravitropic response.

Disciplines
Publication Date
May 27, 2010
Publisher Statement

DOI: http:/​/​dx.​doi.​org/​10.​1105/​tpc.​110

The article was harvested from PubMed Central.
Citation Information
Abidur Rahman, Maho Takahashi, Kyohei Shibasaki, Shuang Wu, et al.. "Gravitropism of Arabidopsis thaliana Roots Requires the Polarization of PIN2 toward the Root Tip in Meristematic Cortical Cells" Plant Cell Vol. 22 Iss. 6 (2010)
Available at: http://works.bepress.com/tobias_baskin/23/