TY - JOUR AU - Hedtmann, Christiane AU - Guo, Wei AU - Reifschneider, Elena AU - Heiber, Isabelle AU - Hiltscher, Heiko AU - van Buer, Jörn AU - Barsch, Aiko AU - Niehaus, Karsten AU - Rowan, Beth AU - Lortzing, Tobias AU - Steppuhn, Anke AU - Baier, Margarete PY - 2017 M3 - Original Research TI - The Plant Immunity Regulating F-Box Protein CPR1 Supports Plastid Function in Absence of Pathogens JO - Frontiers in Plant Science UR - https://www.frontiersin.org/articles/10.3389/fpls.2017.01650 VL - 8 SN - 1664-462X N2 - 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. ER -