LRR-extensins; LRX proteins; Arabidopsis thaliana; cell wall; development; Ca2+ and ROS
Dünser Kai, Gupta Shibu, Herger Aline, Feraru Mugurel I, Ringli Christoph, Kleine‐Vehn Jürgen (2019), Extracellular matrix sensing by FERONIA and Leucine‐Rich Repeat Extensins controls vacuolar expansion during cellular elongation in Arabidopsis thaliana, in The EMBO Journal
, 38(7), e100353-e100353.
Schaufelberger Myriam, Galbier Florian, Herger Aline, de Brito Francisco Rita, Roffler Stefan, Clement Gilles, Diet Anouck, Hörtensteiner Stefan, Wicker Thomas, Ringli Christoph (2019), Mutations in the Arabidopsis ROL17/isopropylmalate synthase 1 locus alter amino acid content, modify the TOR network, and suppress the root hair cell development mutant lrx1, in Journal of Experimental Botany
, 70(8), 2313-2323.
Fabrice Tohnyui Ndinyanka, Vogler Hannes, Draeger Christian, Munglani Gautam, Gupta Shibu, Herger Aline G., Knox Paul, Grossniklaus Ueli, Ringli Christoph (2018), LRX Proteins Play a Crucial Role in Pollen Grain and Pollen Tube Cell Wall Development, in Plant Physiology
, 176(3), 1981-1992.
Plant cells are surrounded by cell walls provide protection against pathogens, wounding, and abiotic stresses. Typically, they are composed of cellulose, hemicellulose, pectins, and structural proteins. Plant cell growth is driven by the internal turgor pressure of the cell but is limited by the cell wall, which has to expand for successful yielding of the cell. Expansion of the cell wall requires metabolic activity in the cell to supply new wall material and the integration of this material into the expanding cell wall. Hence, a network of proteins establishing the cytoplasm - cell wall continuum is necessary to survey, control, and regulate these complex processes in a temporally and spatially coordinated fashion.Leucine-rich repeat-extensin (LRX) proteins are extracellular proteins that are anchored to the cell wall through the extensin (hydroxyproline-rich glycoprotein) domain and bind, via their LRR domain, a so far unknown interaction partner. Of the eleven LRX proteins encoded by the genome of Arabidopsis thaliana, several have been shown to influence cell wall formation. We have mutants of different Arabidopsis LRX genes that are affected in the root, the shoot, or pollen tubes, giving a choice of cellular systems to be used for the different analyses. In addition, a number of rol (repressor of lrx1) mutants were isolated that suppress the root hair growth defect of the lrx1 mutant. Whole genome sequencing of five of these mutants revealed candidate genes for the mutated rol loci, providing an insight into genes and processes that can suppress lrx1. We recently have obtained results indicating that the LRR domain of several LRX proteins associates with the plasma membrane, while the extensin domain has been shown to interact with the cell wall. We propose to investigate this observation in detail as it provides evidence for LRX proteins being plasma membrane. In parallel, we aim to identify the interaction partner(s) of the LRR domain of LRXs, which are likely to localize in or at the plasma membrane. Finally, several of the isolated rol mutants are affected in the homeostasis of reactive oxygen species (ROS). The biological relevance of this observation will be investigated in the rol mutants, while a detailed molecular analysis of the mutated genes will be limited to one or two of these lines.The proposed project will determine the contribution of LRX proteins to the regulation of Ca2+- and possibly ROS- related processes. If LRX proteins indeed represent cell-wall attached linker proteins, this should be substantiated by the planned experiments. Cytological experiments and genetic analyses should also shed light on the potential function of LRXs and their possible interaction partner(s). Together, these experiments should provide a better insight into the poorly understood function of LRX proteins.