Large-Scale Phenomics Identifies Primary and Fine-Tuning Roles for CRKs in Responses Related to Oxidative Stress

Abstract

Cysteine-rich receptor-like kinases (CRKs) are transmembrane proteins characterized by the presence of two domains of unknown function 26 (DUF26) in their ectodomain. The CRKs form one of the largest groups of receptor-like protein kinases in plants, but their biological functions have so far remained largely uncharacterized. We conducted a large-scale phenotyping approach of a nearly complete crk T-DNA insertion line collection showing that CRKs control important aspects of plant development and stress adaptation in response to biotic and abiotic stimuli in a non-redundant fashion. In particular, the analysis of reactive oxygen species (ROS)-related stress responses, such as regulation of the stomatal aperture, suggests that CRKs participate in ROS/redox signalling and sensing. CRKs play general and fine-tuning roles in the regulation of stomatal closure induced by microbial and abiotic cues. Despite their great number and high similarity, large-scale phenotyping identified specific functions in diverse processes for many CRKs and indicated that CRK2 and CRK5 play predominant roles in growth regulation and stress adaptation, respectively. As a whole, the CRKs contribute to specificity in ROS signalling. Individual CRKs control distinct responses in an antagonistic fashion suggesting future potential for using CRKs in genetic approaches to improve plant performance and stress tolerance.

A Key Role for Apoplastic H2O2 in Norway Spruce Phenolic Metabolism

“…Cys-rich receptor-like kinases (CRKs) have been shown to be involved in signaling during biotic and abiotic stresses that generate apoplastic ROS, and CRKs are potential candidates for apoplastic ROS perception and signaling (Bourdais et al, 2015). Among genes coding for CRKs, 47 and nine were up-regulated in lignin-forming conditions and when H 2 O 2 was scavenged, .…”

“…8D). CRK expression has been shown to be modulated in response to ROS-and cellular redox state-related stresses (Lehti-Shiu et al, 2009;Wrzaczek et al, 2010;Bourdais et al, 2015). Moreover, CRKs are thought to be involved in cellular redox and apoplastic ROS sensing by the presence of conserved Cys residues in their apoplastic domain.…”

“…Moreover, CRKs are thought to be involved in cellular redox and apoplastic ROS sensing by the presence of conserved Cys residues in their apoplastic domain. Thus, CRKs are potential candidates for ROS signaling and regulation (Idänheimo et al, 2014;Bourdais et al, 2015).…”

A Cysteine-Rich Protein Kinase Associates with a Membrane Immune Complex and the Cysteine Residues Are Required for Cell Death

“…The DUF26 domain possesses a conserved C-X 8 -C-X 2 -C motif (Ohtake et al, 2000;Chen, 2001). The Cys residues in each DUF26 domain are predicted to form two Cys bridges, which are hypothesized to be targeted for apoplastic redox modification (Bourdais et al, 2015). In the Arabidopsis genome, there are 46 predicted CRKs, eight plasmodesmata-located proteins (PDLPs), and more than 50 Cys-rich repeat secretory proteins that possess DUF26 domains (Chen, 2001;Amari et al, 2010;Bourdais et al, 2015).…”

“…Previous studies have demonstrated that Arabidopsis CRKs are transcriptionally induced in response to abiotic stresses, including salicylic acid, ozone, UV light, salt, and drought treatments (Chen et al, 2003(Chen et al, , 2004Wrzaczek et al, 2010;Bourdais et al, 2015;Yeh et al, 2015). A subset of CRKs is strongly induced in response to pathogens and PAMP treatment (Wrzaczek et al, 2010;Bourdais et al, 2015).…”