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  • The EMBO Journal (2006) 25, 2007 - 2016
  • doi:10.1038/sj.emboj.7601084

Published online: 13 April 2006

Role of SGT1 in resistance protein accumulation in plant immunity

Cristina Azevedo1,a, Shigeyuki Betsuyaku2,a, Jack Peart1, Akira Takahashi1, Laurent Noël2,3, Ari Sadanandom1, Catarina Casais1, Jane Parker2 and Ken Shirasu1

  1. The Sainsbury Laboratory, John Innes Centre, Norwich, UK
  2. Max-Planck-Institut für Züchtungsforschung, Department of Plant Microbe Interactions, Köln, Germany
  3. Laboratoire de Biologie du Développement des Plantes, UMR6191 CNRS-CEA, Université Aix-Marseille II, CEN Cadarache, Saint Paul-lez-Durance Cedex, France

Correspondence to:

Jane Parker, Max-Planck-Institut für Züchtungsforschung, Department of Plant Microbe Interactions, Carl-von-Linné-Weg 10, 50829 Köln, Germany. Fax:+49 221 5062353; E-mail: parker@mpiz-koeln.mpg.de

Ken Shirasu, RIKEN Plant Science Center, 1-7-22 Suehiro, Tsurumi, Yokohama 230-0045, Japan. Tel.: +81 45503 9445; Fax: +81 45503 9573; E-mail: ken.shirasu@psc.riken.jp

aEqual first authors

Received 16 August 2005; Accepted 16 March 2006

A highly conserved eukaryotic protein SGT1 binds specifically to the molecular chaperone, HSP90. In plants, SGT1 positively regulates disease resistance conferred by many Resistance (R) proteins and developmental responses to the phytohormone, auxin. We show that silencing of SGT1 in Nicotiana benthamiana causes a reduction in steady-state levels of the R protein, Rx. These data support a role of SGT1 in R protein accumulation, possibly at the level of complex assembly. In Arabidopsis, two SGT1 proteins, AtSGT1a and AtSGT1b, are functionally redundant early in development. AtSGT1a and AtSGT1b are induced in leaves upon infection and either protein can function in resistance once a certain level is attained, depending on the R protein tested. In unchallenged tissues, steady-state AtSGT1b levels are at least four times greater than AtSGT1a. While the respective tetratricopeptide repeat (TPR) domains of SGT1a and SGT1b control protein accumulation, they are dispensable for intrinsic functions of SGT1 in resistance and auxin responses.

  • Keywords:

    • cell death,
    • chaperone,
    • CHORD,
    • HSP90,
    • TPR