Plant Molecular Biology

, Volume 63, Issue 2, pp 273–287

Aconitase plays a role in regulating resistance to oxidative stress and cell death in Arabidopsis and Nicotiana benthamiana

  • Wolfgang Moeder
  • Olga del Pozo
  • Duroy A. Navarre
  • Gregory B. Martin
  • Daniel F. Klessig
Article

Abstract

In animals, aconitase is a bifunctional protein. When an iron-sulfur cluster is present in its catalytic center, aconitase displays enzymatic activity; when this cluster is lost, it switches to an RNA-binding protein that regulates the translatability or stability of certain transcripts. To investigate the role of aconitase in plants, we assessed its ability to bind mRNA. Recombinant aconitase failed to bind an iron responsive element (IRE) from the human ferritin gene. However, it bound the 5′ UTR of the Arabidopsis chloroplastic CuZn superoxide dismutase 2 (CSD2) mRNA, and this binding was specific. Arabidopsis aconitase knockout (KO) plants were found to have significantly less chlorosis after treatment with the superoxide-generating compound, paraquat. This phenotype correlated with delayed induction of the antioxidant gene GST1, suggesting that these KO lines are more tolerant to oxidative stress. Increased levels of CSD2 mRNAs were observed in the KO lines, although the level of CSD2 protein was not affected. Virus-induced gene silencing (VIGS) of aconitase in Nicotiana benthamiana caused a 90% reduction in aconitase activity, stunting, spontaneous necrotic lesions, and increased resistance to paraquat. The silenced plants also had less cell death after transient co-expression of the AvrPto and Pto proteins or the pro-apoptotic protein Bax. Following inoculation with Pseudomonas syringae pv. tabaci carrying avrPto, aconitase-silenced N. benthamiana plants expressing the Pto transgene displayed a delayed hypersensitive response (HR) and supported higher levels of bacterial growth. Disease-associated cell death in N. benthamiana inoculated with P. s. pv. tabaci was also reduced. Taken together, these results suggest that aconitase plays a role in mediating oxidative stress and regulating cell death.

Keywords

Aconitase Arabidopsis Cell death Nicotiana benthamiana Oxidative stress Superoxide dismutase RNA-binding VIGS 

Abbreviations

CSD2

CuZn superoxide dismutase 2

GMSA

Gel mobility shift assay

IRE

Iron responsive element

IRP-1

Iron regulatory protein 1

mt

mitochondrial

UTR

Untranslated region

VIGS

Virus-induced gene silencing

Copyright information

© Springer Science+Business Media B.V. 2006

Authors and Affiliations

  • Wolfgang Moeder
    • 1
    • 2
  • Olga del Pozo
    • 1
    • 3
  • Duroy A. Navarre
    • 4
    • 5
  • Gregory B. Martin
    • 1
  • Daniel F. Klessig
    • 1
  1. 1.Boyce Thompson Institute for Plant ResearchIthacaUSA
  2. 2.Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
  3. 3.Instituto de Bioquímica Vegetal y FotosíntesisSevillaSpain
  4. 4.Agricultural Research ServiceUSDAProsserUSA
  5. 5.Department Plant PathologyWashington State UniversityProsserUSA

Personalised recommendations