Planta

, Volume 226, Issue 1, pp 57–71

Silencing of PR-10-like proteins in Medicago truncatula results in an antagonistic induction of other PR proteins and in an increased tolerance upon infection with the oomycete Aphanomyces euteiches

  • Frank Colditz
  • Karsten Niehaus
  • Franziska Krajinski
Original Article

DOI: 10.1007/s00425-006-0466-y

Cite this article as:
Colditz, F., Niehaus, K. & Krajinski, F. Planta (2007) 226: 57. doi:10.1007/s00425-006-0466-y

Abstract

Recent studies on the root proteome of Medicago truncatula (Gaertn.) showed an induction of pathogenesis-related (PR) proteins of the class 10 after infection with the oomycete pathogen Aphanomyces euteiches (Drechs.). To get insights into the function of these proteins during the parasitic root–microbe association, a gene knockdown approach using RNAi was carried out. Agrobacterium rhizogenes-mediated transformation of M. truncatula roots led to a knockdown of the MedicagoPR10-1 gene in transgenic in vitro root cultures. Proteomic analyses of the MtPr10-1i root cultures showed that MtPr10-1 was efficiently knocked down in two MtPr10-1i lines. Moreover, five additional PR-10-type proteins annotated as abscisic acid responsive proteins (ABR17s) revealed also an almost complete silencing in these two lines. Inoculation of the root cultures with the oomycete root pathogen A. euteiches resulted in a clearly reduced colonization and thus in a suppressed infection development in MtPr10-1i roots as compared to that in roots of the transformation controls. In addition, MtPr10-1 silencing led to the induction of a new set of PR proteins after infection with A. euteiches including the de novo induction of two isoforms of thaumatin-like proteins (PR-5b), which were not detectable in A. euteiches-infected control roots. Thus, antagonistic induction of other PR proteins, which are normally repressed due to PR-10 expression, is supposed to cause an increased resistance of M. truncatula upon an A. euteiches in vitro infection. The results were also further confirmed by detecting increased PR-5b induction levels in 2-D gels of a previously analyzed M. truncatula line (F83.005-9) exhibiting increased A. euteiches tolerance associated with reduced PR-10 induction levels.

Keywords

AphanomycesMedicagoPathogenesis-related protein 5b (PR-5b)Pathogenesis-related protein 10 (PR-10)ProteomicsRNAi

Abbreviations

ALP

Alkaline phosphatase

Avr

Avirulence

CBB

Coomassie Brilliant Blue

dpi

Days post inoculation

EST

Expressed sequence tag

MALDI-TOF/MS

Matrix-assisted laser desorption/ionization-time of flight/mass spectrometry

MtGI

Medicago truncatula Gene Index

PMF

Peptide mass fingerprinting

PR proteins

Pathogenesis-related proteins

TC

Tentative consensus sequence

RNAi

RNA interference

TIGR

The Institute for Genome Research, Rockville, MD, USA

2-DE

Two-dimensional electrophoresis

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Frank Colditz
    • 1
  • Karsten Niehaus
    • 1
  • Franziska Krajinski
    • 2
  1. 1.Department 7, Proteome and Metabolome ResearchUniversity of BielefeldBielefeldGermany
  2. 2.Institute of Plant Genetics, Department of Molecular GeneticsUniversity of HannoverHannoverGermany