Current Genetics

, Volume 53, Issue 3, pp 163–174

Functional analysis of a fungal endophyte stress-activated MAP kinase

  • Carla J. Eaton
  • Isabelle Jourdain
  • Simon J. Foster
  • Jeremy S. Hyams
  • Barry Scott
Research Article

DOI: 10.1007/s00294-007-0174-6

Cite this article as:
Eaton, C.J., Jourdain, I., Foster, S.J. et al. Curr Genet (2008) 53: 163. doi:10.1007/s00294-007-0174-6

Abstract

The ability of fungi to sense and respond rapidly to environmental stress is crucial for their survival in the wild. One of the most important pathways involved in this response is the stress-activated MAP (mitogen-activated protein) kinase pathway. We report here on the isolation of the stress-activated MAP kinase, sakA, from the fungal endophyte Epichloë festucae. Complementation of the stress sensitivity and cell cycle defects of an Schizosaccharomyces pombe sty1Δ mutant with sakA confirmed it encodes a functional MAP kinase. Analysis of an E. festucae ΔsakA mutant revealed sakA is essential for growth under conditions of temperature and osmotic stress in culture, and for sensitivity to the fungicide fludioxonil. However, the ΔsakA mutant shows no increased sensitivity to hydrogen peroxide. Given sakA can rescue the sty1Δ mutant from sensitivity to oxidative stress, SakA has the potential to sense and transduce oxidative stress signals. The ΔsakA mutant is also defective in conidia formation, suggesting a role for SakA in asexual development of E. festucae. The detection of elevated hydrogen peroxide production in the ΔsakA mutant suggests there may be a link between MAP kinase and ROS (reactive oxygen species) signalling pathways in E. festucae.

Keywords

MAP kinase S. pombe E. festucae Hog1 Sty1 SakA NADPH oxidase Reactive oxygen species 

Supplementary material

294_2007_174_MOESM1_ESM.doc (40 kb)
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294_2007_174_MOESM3_ESM.tif (364 kb)
Amino acid sequence alignment of fungal MAP kinases. The predicted amino acid sequence of E. festucae SakA (EfSakA) is aligned with stress MAP kinases from F. graminearum (FGSG_09612), N. crassa (NcOs-2), M. grisea (MgOSM1), and S. pombe (SpSty1); and two non-stress activated MAP kinases from F. graminearum (FGSG_06385 and FGSG_10313). Dashed black boxing indicates regions to which degenerate primers sak1 and sak2 were designed. Solid boxing indicates the position of the highly conserved TGY lip
294_2007_174_MOESM4_ESM.tif (661 kb)
Agarose gel electrophoresis of sakA RT-PCR products. RT-PCR amplification with primers sak24 and sak39 was performed on cDNA isolated from sty1D expressing sakA gDNA (lane 1), no RT control (lane 2), E. festucae genomic DNA (lane 3) and E. festucae cDNA (lane 4). M, 1 kb plus ladder (Invitrogen)
294_2007_174_MOESM5_ESM.tif (789 kb)
An E. festucae sakA C-terminal GFP fusion protein rescues the S. pombe sty1Δ mutant from its osmosensitivity defect. Wild-type and the sty1Δ mutant carrying pREP81-GFP or sakA-GFP were streaked on minimal media (EMM) containing either no stress agents (A) or 1.5 M sorbitol (B)

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Carla J. Eaton
    • 1
    • 2
  • Isabelle Jourdain
    • 1
  • Simon J. Foster
    • 1
    • 3
  • Jeremy S. Hyams
    • 1
  • Barry Scott
    • 1
    • 2
  1. 1.Institute of Molecular BioSciencesMassey UniversityPalmerston NorthNew Zealand
  2. 2.National Centre for BioProtectionMassey UniversityPalmerston NorthNew Zealand
  3. 3.The Sainsbury LaboratoryJohn Innes CentreNorwichUK

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