Frontiers in Plant Science (Sep 2017)

The Plant Immunity Regulating F-Box Protein CPR1 Supports Plastid Function in Absence of Pathogens

  • Christiane Hedtmann,
  • Wei Guo,
  • Elena Reifschneider,
  • Isabelle Heiber,
  • Heiko Hiltscher,
  • Jörn van Buer,
  • Aiko Barsch,
  • Karsten Niehaus,
  • Beth Rowan,
  • Tobias Lortzing,
  • Anke Steppuhn,
  • Margarete Baier

DOI
https://doi.org/10.3389/fpls.2017.01650
Journal volume & issue
Vol. 8

Abstract

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The redox imbalanced 6 mutant (rimb6) of Arabidopsis thaliana was isolated in a genetic screening approach for mutants with defects in chloroplast-to-nucleus redox signaling. It has an atypically low activation status of the 2-Cys peroxiredoxin-A promoter in the seedling stage. rimb6 shows wildtype-like germination, seedling development and greening, but slower growth and reduced biomass in the rosette stage. Mapping of the casual mutation revealed that rimb6 carries a single nucleotide polymorphism in the gene encoding CONSTITUTIVE EXPRESSER OF PATHOGENESIS RELATED (PR) GENES 1, CPR1 (At4g12560), leading to a premature stop codon. CPR1 is known as a repressor of pathogen signaling and regulator of microtubule organization. Allelism of rimb6 and cpr1 revealed a function of CPR1 in chloroplast stress protection. Expression studies in pathogen signaling mutants demonstrated that CPR1-mediated activation of genes for photosynthesis and chloroplast antioxidant protection is, in contrast to activation of pathogen responses, regulated independently from PAD4-controlled salicylic acid (SA) accumulation. We conclude that the support of plastid function is a basic, SA-independent function of CPR1.

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