Armadillo-related proteins promote lateral root development in Arabidopsis

doi:10.1073/pnas.0507575103

Armadillo-related proteins promote lateral root development in Arabidopsis

^*School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom; ^‡Unité Mixte de Recherche 1098 Institut de Recherche pour le Développement, BP 64501, 911 Avenue Agropolis, 34394 Montpellier cedex 5, France; and ^§Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, United Kingdom

Edited by Enrico Coen, John Innes Centre, Norwich, United Kingdom, and approved December 5, 2005 (received for review August 31, 2005)

Abstract

Armadillo/β-catenin and related proteins have important functions during animal and Dictyostelium development, regulating cell differentiation, proliferation, and adhesion. Armadillo-repeatcontaining proteins also exist in plants, but the majority have unknown roles. The Arabidopsis genes that show greatest sequence homology to Armadillo/β-catenin are called ARABIDILLO-1 and -2. Here, we demonstrate that ARABIDILLO-1 and -2 promote lateral root development. arabidillo-1/-2 mutants form fewer lateral roots, and ARABIDILLO-1-overexpressing lines produce more lateral roots than wild-type seedlings. ARABIDILLO-yellow fluorescent protein fusions are nuclear. ARABIDILLO proteins contain an F-box motif, and thus may target other proteins for proteasomal degradation. Overexpression of ARABIDILLO-1 protein fragments, including F-box fragments, in wild-type seedlings reduces lateral root formation to the level of the arabidillo-1/-2 mutant. We have shown that plant β-catenin-related proteins regulate root development. We suggest that ARABIDILLO proteins may target an inhibitor of lateral root development for degradation and propose that Arabidopsis β-catenin-related proteins define a previously uncharacterized pathway that promotes root branching.

Footnotes

↵ † To whom correspondence should be addressed. E-mail: j.c.coates{at}bham.ac.uk.
Author contributions: J.C.C. designed research; J.C.C. and L.L. performed research; J.C.C. contributed new reagents/analytic tools; J.C.C., L.L., and J.H. analyzed data; and J.C.C. and L.L. wrote the paper.
Conflict of interest statement: No conflicts declared.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations: Arm, Armadillo; GUS, β-glucuronidase; IAA, indole-3 acetic acid; MS, Murashige and Skoog medium; NLS, nuclear-localization signal; YFP yellow fluorescent protein; 2,4D, 2,4 dichlorophenoxyacetic acid.