Quantitative phosphoproteomics of tomato mounting a hypersensitive response reveals a swift suppression of photosynthetic activity and a differential role for Hsp90 isoforms

I.J.E. Stulemeijer, M.H.A.J. Joosten, O.N. Jensen

Research output: Contribution to journalArticleAcademicpeer-review

36 Citations (Scopus)

Abstract

An important mechanism by which plants defend themselves against pathogens is the rapid execution of a hypersensitive response (HR). Tomato plants containing the Cf-4 resistance gene mount an HR that relies on the activation of phosphorylation cascades, when challenged with the Avr4 elicitor secreted by the pathogenic fungus Cladosporium fulvum. Phosphopeptides were isolated from tomato seedlings expressing both Cf-4 and Avr4 using titanium dioxide columns and LC-MS/MS analysis led to the identification of 50 phosphoproteins, most of which have not been described in tomato before. Phosphopeptides were quantified using a label-free approach based on the MS peak areas. We identified 12 phosphopeptides for which the abundance changed upon HR initiation, as compared to control seedlings. Our results suggest that photosynthetic activity is specifically suppressed in a phosphorylation-dependent way during the very early stages of HR development. In addition, phosphopeptides originating from four Hsp90 isoforms exhibited altered abundances in Cf-4/Avr4 seedlings compared to control seedlings, suggesting that the isoforms of this chaperone protein have a different function in defense signaling. We show that label-free relative quantification of the phosphoproteome of complex samples is feasible, allowing extension of our knowledge on the general physiology and defense signaling of plants mounting the HR.
Original languageEnglish
Pages (from-to)1168-1182
JournalJournal of Proteome Research
Volume8
Issue number3
DOIs
Publication statusPublished - 2009

Keywords

  • dependent protein-kinase
  • highly selective enrichment
  • plant-pathogen interactions
  • innate immune-responses
  • programmed cell-death
  • heat-shock-protein
  • cladosporium-fulvum
  • mass-spectrometry
  • plasma-membrane
  • functional-analysis

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