Scientific Reports (Aug 2017)

PRR2, a pseudo-response regulator, promotes salicylic acid and camalexin accumulation during plant immunity

  • C. Cheval,
  • M. Perez,
  • L. J. Leba,
  • B. Ranty,
  • A. Perochon,
  • M. Reichelt,
  • A. Mithöfer,
  • E. Robe,
  • C. Mazars,
  • J. P. Galaud,
  • D. Aldon

DOI
https://doi.org/10.1038/s41598-017-07535-8
Journal volume & issue
Vol. 7, no. 1
pp. 1 – 13

Abstract

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Abstract Calcium signalling mediated by Calmodulin (CaM) and calmodulin-like (CML) proteins is critical to plant immunity. CaM and CML regulate a wide range of target proteins and cellular responses. While many CaM-binding proteins have been identified, few have been characterized for their specific role in plant immunity. Here, we report new data on the biological function of a CML-interacting partner, PRR2 (PSEUDO-RESPONSE REGULATOR 2), a plant specific transcription factor. Until now, the physiological relevance of PRR2 remained largely unknown. Using a reverse genetic strategy in A. thaliana, we identified PRR2 as a positive regulator of plant immunity. We propose that PRR2 contributes to salicylic acid (SA)-dependent responses when challenged with the phytopathogenic bacterium Pseudomonas syringae. PRR2 is transcriptionally upregulated by SA and P. syringae, enhances SA biosynthesis and SA signalling responses; e.g. in response to P. syringae, PRR2 induces the production of SA and the accumulation of the defence-related protein PR1. Moreover, PRR2 overexpressing lines exhibit an enhanced production of camalexin, a phytoalexin that confers enhanced resistance against pathogens. Together, these data reveal the importance of PRR2 in plant immune responses against P. syringae and suggest a novel function for this particular plant specific transcription factor in plant physiology.