title: Receptor-like cytoplasmic kinase MARIS functions downstream of CrRLK1L-dependent signaling during tip growth.
abstract: Growing plant cells need to rigorously coordinate external signals with internal processes. For instance, the maintenance of cell wall (CW) integrity requires the coordination of CW sensing with CW remodeling and biosynthesis to avoid growth arrest or integrity loss. Despite the involvement of receptor-like kinases (RLKs) of the Catharanthus roseus RLK1-like (CrRLK1L) subfamily and the reactive oxygen species-producing NADPH oxidases, it remains largely unknown how this coordination is achieved. ANXUR1 (ANX1) and ANX2, two redundant members of the CrRLK1L subfamily, are required for tip growth of the pollen tube (PT), and their closest homolog, FERONIA, controls root-hair tip growth. Previously, we showed that ANX1 overexpression mildly inhibits PT growth by oversecretion of CW material, whereas pollen tubes of anx1 anx2 double mutants burst spontaneously after germination. Here, we report the identification of suppressor mutants with improved fertility caused by the rescue of anx1 anx2 pollen tube bursting. Mapping of one these mutants revealed an R240C nonsynonymous substitution in the activation loop of a receptor-like cytoplasmic kinase (RLCK), which we named MARIS (MRI). We show that MRI is a plasma membrane-localized member of the RLCK-VIII subfamily and is preferentially expressed in both PTs and root hairs. Interestingly, mri-knockout mutants display spontaneous PT and root-hair bursting. Moreover, expression of the MRI(R240C) mutant, but not its wild-type form, partially rescues the bursting phenotypes of anx1 anx2 PTs and fer root hairs but strongly inhibits wild-type tip growth. Thus, our findings identify a novel positive component of the CrRLK1L-dependent signaling cascade that coordinates CW integrity and tip growth.
authors.affiliation: Biocenter, Botanical Institute, University of Cologne, 50674 Cologne, Germany; Institute of Plant Biology, University of Zurich, 8008 Zurich, Switzerland; Zurich-Basel Plant Science Center, University of Zurich, 8008 Zurich, Switzerland aboisson@uni-koeln.de.
authors.forename: Aurélien
authors.initials: A
authors.lastname: Boisson-Dernier
authors.affiliation: Biocenter, Botanical Institute, University of Cologne, 50674 Cologne, Germany; Institute of Plant Biology, University of Zurich, 8008 Zurich, Switzerland; Zurich-Basel Plant Science Center, University of Zurich, 8008 Zurich, Switzerland.
authors.forename: Christina Maria
authors.initials: CM
authors.lastname: Franck
authors.affiliation: Institute of Plant Biology, University of Zurich, 8008 Zurich, Switzerland; Zurich-Basel Plant Science Center, University of Zurich, 8008 Zurich, Switzerland.
authors.forename: Dmytro S
authors.identifier: http://orcid.org/0000-0003-0543-0758
authors.initials: DS
authors.lastname: Lituiev
authors.affiliation: Institute of Plant Biology, University of Zurich, 8008 Zurich, Switzerland; Zurich-Basel Plant Science Center, University of Zurich, 8008 Zurich, Switzerland.
authors.forename: Ueli
authors.initials: U
authors.lastname: Grossniklaus
mesh_terms: D029681:Arabidopsis Proteins / Q000378:metabolism*; D030008:Catharanthus / Q000201:enzymology*; D003593:Cytoplasm / Q000201:enzymology*; D007091:Image Processing, Computer-Assisted; D008857:Microscopy, Interference; D018517:Plant Roots / Q000201:enzymology* / Q000254:growth & development; D053205:Pollen Tube / Q000201:enzymology* / Q000254:growth & development; D011494:Protein Kinases / Q000378:metabolism*; D054557:Receptor-Like Protein Tyrosine Phosphatases / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; C000604170:MARIS protein, Arabidopsis; D011494:Protein Kinases; D054557:Receptor-Like Protein Tyrosine Phosphatases
keywords: Arabidopsis; cell wall integrity; pollen tube; receptor-like kinase signaling; root hair