Planta

, Volume 225, Issue 6, pp 1559–1571

Activation of members of a MAPK module in β-glucan elicitor-mediated non-host resistance of soybean

  • Andrea Daxberger
  • Andrea Nemak
  • Axel Mithöfer
  • Judith Fliegmann
  • Wilco Ligterink
  • Heribert Hirt
  • Jürgen Ebel
Original Article

DOI: 10.1007/s00425-006-0442-6

Cite this article as:
Daxberger, A., Nemak, A., Mithöfer, A. et al. Planta (2007) 225: 1559. doi:10.1007/s00425-006-0442-6

Abstract

Plants recognize microbial pathogens by discriminating pathogen-associated molecular patterns from self-structures. We study the non-host disease resistance of soybean (Glycine max L.) to the oomycete, Phytophthora sojae. Soybean senses a specific molecular pattern consisting of a branched heptaglucoside that is present in the oomycetal cell walls. Recognition of this elicitor may be achieved through a β-glucan-binding protein, which forms part of a proposed receptor complex. Subsequently, soybean mounts a complex defense response, which includes the increase of the cytosolic calcium concentration, the production of reactive oxygen species, and the activation of genes responsible for the synthesis of phytoalexins. We now report the identification of two mitogen-activated protein kinases (MAPKs) and one MAPK kinase (MAPKK) that may function as signaling elements in triggering the resistance response. The use of specific antisera enabled the identification of GmMPKs 3 and 6 whose activity is enhanced within the signaling pathway leading to defense reactions. Elicitor specificity of MAPK activation as well as the sensitivity against inhibitors suggested these kinases as part of the β-glucan signal transduction pathway. An upstream GmMKK1 was identified based on sequence similarity to other plant MAPKKs and its interaction with the MAPKs was analyzed. Recombinant GmMKK1 interacted predominantly with GmMPK6, with concomitant phosphorylation of the MAPK protein. Moreover, a preferential physical interaction between GmMKK1 and GmMPK6 was demonstrated in yeast. These results suggest a role of a MAPK cascade in mediating β-glucan signal transduction in soybean, similar to other triggers that activate MAPKs during innate immune responses in plants.

Keywords

β-Glucan elicitors Glycine Mitogen-activated protein kinase (MAPK) signaling Phytophthora Protein interaction 

Abbreviations

A9C

Anthracene-9-carboxylate

DP

Degree of polymerization

DPI

Diphenyleneiodonium

EGTA

Ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid

EST

Expressed sequence tag

IMAC

Immobilized metal chelate affinity chromatography

MAPK

(MPK) mitogen-activated protein kinase

MAPKK

(MKK) MAPK kinase

MBP

Myelin basic protein

NPPB

5-Nitro-2-(3-phenylpropylamino)-benzoate

PAGE

Polyacrylamide gelelectrophoresis

SA

Salicylic acid

SSC

Standard saline citrate

Supplementary material

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  • Andrea Daxberger
    • 1
  • Andrea Nemak
    • 1
  • Axel Mithöfer
    • 2
  • Judith Fliegmann
    • 1
  • Wilco Ligterink
    • 4
  • Heribert Hirt
    • 3
  • Jürgen Ebel
    • 1
  1. 1.Department Biologie I/BotanikLudwig-Maximilians-UniversitätMünchenGermany
  2. 2.Max-Planck-Institut für Chemische ÖkologieBioorganische ChemieJenaGermany
  3. 3.Department für Pflanzenmolekularbiologie, Max F. Perutz LaboratoriesUniversity of ViennaViennaAustria
  4. 4.Laboratorium voor PlantenfysiologieBotanisch CentrumWageningenThe Netherlands

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