Reduced expression of α-tubulin genes in Arabidopsis thaliana specifically affects root growth and morphology, root hair development and root gravitropism

Authors

  • Yiqun Bao,

    1. Laboratory of Plant Cell Biology, Institute of Molecular Agrobiology, 1 research link, National University of Singapore, 117604, Singapore, and
    Search for more papers by this author
  • Benedikt Kost,

    1. Laboratory of Plant Cell Biology, Institute of Molecular Agrobiology, 1 research link, National University of Singapore, 117604, Singapore, and
    Search for more papers by this author
  • Nam-Hai Chua

    Corresponding author
    1. Laboratory of Plant Molecular Biology, the Rockefeller University, 1230 York Avenue, New York, NY 10021–6399, USA
    Search for more papers by this author

For correspondence (fax +1 212 327 8327; e-mail: Chua@rockvax.rockefeller.edu).

Summary

Different α-tubulin cDNA sequences fused in an antisense orientation to a CaMV 35S promoter were introduced into Arabidopsis thaliana plants. Several independent transgenic lines that showed a moderate but clear reduction of α-tubulin gene expression (TUA6/AS lines) were obtained and phenotypically characterized. Although no apparent abnormalities were detected in the aerial parts of TUA6/AS plants, root development was severely affected. Cells in TUA6/AS root tips were found to contain aberrant microtubular structures, to expand abnormally and to be unable to undergo regular cell division. These cellular defects caused a dramatic radial expansion of the root tip and inhibited root elongation. In addition, TUA6/AS roots displayed ectopic formation of root hairs, root hair branching and a reduced ability to respond to gravitropic challenges. Our results contribute to an improved understanding of the different roles microtubules play during root development and demonstrate that reverse genetics is a powerful tool to analyze cytoskeletal functions during plant organogenesis.

Ancillary