Regulation of basal resistance by a powdery mildew‐induced cysteine‐rich receptor‐like protein kinase in barley

Abstract

The receptor-like protein kinases (RLKs) constitute a large and diverse group of proteins controlling numerous plant physiological processes, including development, hormone perception and stress responses. The cysteine-rich RLKs (CRKs) represent a prominent subfamily of transmembrane-anchored RLKs. We have identified a putative barley (Hordeum vulgare) CRK gene family member, designated HvCRK1. The mature putative protein comprises 645 amino acids, and includes a putative receptor domain containing two characteristic 'domain 26 of unknown function' (duf26) domains in the N-terminal region, followed by a rather short 17-amino-acid transmembrane domain, which includes an AAA motif, two features characteristic of endoplasmic reticulum (ER)-targeted proteins and, finally, a characteristic putative protein kinase domain in the C-terminus. The HvCRK1 transcript was isolated from leaves inoculated with the biotrophic fungal pathogen Blumeria graminis f.sp. hordei (Bgh). HvCRK1 transcripts were observed to accumulate transiently following Bgh inoculation of susceptible barley. Transient silencing of HvCRK1 expression in bombarded epidermal cells led to enhanced resistance to Bgh, but did not affect R-gene-mediated resistance. Silencing of HvCRK1 phenocopied the effective penetration resistance found in mlo-resistant barley plants, and the possible link between HvCRK1 and MLO was substantiated by the fact that HvCRK1 induction on Bgh inoculation was dependent on Mlo. Finally, using both experimental and in silico approaches, we demonstrated that HvCRK1 localizes to the ER of barley cells. The negative effect on basal resistance against Bgh and the functional aspects of MLO- and ER-localized HvCRK1 signalling on Bgh inoculation are discussed.

A Secreted Protein with Plant-Specific Cysteine-Rich Motif Functions as a Mannose-Binding Lectin That Exhibits Antifungal Activity

“…The GH domains, which usually contain six Cys residues, have also been found in the extracellular regions of Arabidopsis CRKs (Supplemental Fig. S8), several members of which function in salicylic acid-dependent defense pathways, oxidative stress responses, and regulation of ABA signaling (Czernic et al, 1999;Du and Chen., 2000;Ohtake et al, 2000;Chen et al, 2003;Acharya et al, 2007;Wrzaczek et al, 2010;Rayapuram et al, 2012;Tanaka et al, 2012).…”

“…Several CRKs are involved in resistance to bacterial and fungal pathogens, hypersensitive response-related cell death, oxidative stress responses, and salicylic acid-dependent defense pathways (Czernic et al, 1999;Du and Chen., 2000;Ohtake et al, 2000;Chen et al, 2003;Acharya et al, 2007;Wrzaczek et al, 2010;Rayapuram et al, 2012). A recent study also showed that some CRKs regulate ABA signaling and osmotic stress responses (Tanaka et al, 2012).…”

Plant Innate Immunity: Perception of Conserved Microbial Signatures

“…Several additional coregulatory RKs have been implicated in the perception of conserved microbial signatures. These include AtFER (FERONIA), AtCRK20a (cysteine rich kinase 20a), HvCRK1 (cysteine rich kinase 1), and many others (57,113,115,171). An important future research focus will be to elucidate the explicit role of these predicted coregulatory RKs in PTI.…”

Novel Set of Sex-Specific PCR-Based Markers Reveals New Hypothesis of Sex Differentiation in Date Palm

“…Several CRKs are known to be involved in resistance to bacterial and fungal pathogens, hypersensitive response-related cell death, oxidative stress responses, and salicylic acid-dependent defense pathways [48,49]. A recent study also showed that some CRKs regulate ABA signaling and osmotic stress responses [50].…”