The Arabidopsis receptor kinase STRUBBELIG regulates the response to cellulose deficiency

Abstract

23 24 Short title: SUB mediates cell wall stress signaling 25 26 Abstract 29 Plant cells are encased in a semi-rigid cell wall of complex build. As a consequence, 30 cell wall remodeling is essential for the control of growth and development as well as 31 the regulation of abiotic and biotic stress responses. Plant cells actively sense physico-32 chemical changes in the cell wall and initiate corresponding cellular responses. 33 However, the underlying cell wall monitoring mechanisms remain poorly understood.34 In Arabidopsis the atypical receptor kinase STRUBBELIG (SUB) mediates tissue 35 morphogenesis. Here, we show that SUB-mediated signal transduction also regulates 36 the cellular response to a reduction in the biosynthesis of cellulose, a central 37 carbohydrate component of the cell wall. SUB signaling affects early increase of 38 intracellular reactive oxygen species, stress gene induction as well as ectopic lignin 39 and callose accumulation upon exogenous application of the cellulose biosynthesis 40 inhibitor isoxaben. Moreover, our data reveal that SUB signaling is required for 41 maintaining cell size and shape of root epidermal cells and the recovery of root 42 growth after transient exposure to isoxaben. SUB is also required for root growth 43 arrest in mutants with defective cellulose biosynthesis. Genetic data further indicate 44 that SUB controls the isoxaben-induced cell wall stress response independently from 45 other known receptor kinase genes mediating this response, such as THESEUS1 or 46 MIK2. We propose that SUB functions in a least two distinct biological processes: the 47 control of tissue morphogenesis and the response to cell wall damage. Taken together, 48 our results reveal a novel signal transduction pathway that contributes to the 49 molecular framework underlying cell wall integrity signaling. 50 51 52 3 53 Author Summary54 Plant cells are encapsulated by a semi-rigid and biochemically complex cell wall. This 55 particular feature has consequences for multiple biologically important processes, 56 such as cell and organ growth or various stress responses. For a plant cell to grow the 57 cell wall has to be modified to allow cell expansion, which is driven by outward-58 directed turgor pressure generated inside the cell. In return, changes in cell wall 59 architecture need to be monitored by individual cells, and to be coordinated across 60 cells in a growing tissue, for an organ to attain its regular size and shape. Cell wall 61 surveillance also comes also into play in the reaction against certain stresses, 62 including for example infection by plant pathogens, many of which break through the 63 cell wall during infection, thereby generating wall-derived factors that can induce 64 defense responses. There is only limited knowledge regarding the molecular system 65 that monitors the composition and status of the cell wall. Here we provide further 66 insight into the mechanism. We show that the cell surface receptor STRUBBELIG, 67 previously known to control organ development in Ar...

The plant cell wall: Biosynthesis, construction, and functions

“…Plant cell expansion is an important manifestation of plant growth which requires some wall polymers to become loosened and degraded and new wall components to be incorporated to increase cell volume (Chebli and Geitmann, 2017; Cosgrove, 2018). Expansins and multiple endotransglycosylase/hydrolases, such as polygalacturonases and PLs, are involved in wall extension and remodeling (Xiao et al, 2014; Cosgrove, 2015; Rui et al, 2017), leading to so‐called turgor‐driven expansion (Cosgrove, 2018).…”

“…Another CWI signaling pathway is mediated by PME inhibitor5 (PMEI5)-RLP44, which functions with the BR co-receptor BAK1 to synergistically control CWI and cell growth (Wolf et al, 2012(Wolf et al, , 2014Wolf, 2017). In addition, STRUBBELIG (SUB), an atypical receptor-like kinase, regulates isoxaben-induced cell wall stress responses (Chaudhary et al, 2020). Once additional signaling pathways are identified, perhaps the framework of the plant CWI machinery will be uncovered in the near future.…”

Plant plasma membrane‐resident receptors: Surveillance for infections and coordination for growth and development

“…Further, recent studies revealed new receptors as a critical component in regulating plant growth and development processes. For instance, the Arabidopsis STRUBBELIG (SUB) receptor is involved in tissue morphogenesis and controls the composition of the plant cell wall (Chaudhary et al, 2020). Meanwhile, the kinase-inactive RLKs MUS-TACHES (MUS) and MUSTACHES-LIKE (MUL) can control lateral root development (Xun et al, 2020).…”

Immune elicitation by sensing the conserved signature from phytocytokines and microbes via theArabidopsisMIK2 receptor

“…The ligand of MIK2 remains enigmatic. In addition, MIK2 plays a role in response to diverse environmental stresses, including cell wall integrity sensing, salt stress tolerance, and resistance to the soil-borne fungal pathogen Fusarium oxysporum [26][27][28][29] . A recent study suggested that MIK2 functions as a PRR perceiving an unknown peptide elicitor from F. oxysporum to activate plant immunity 30 .…”