A domain swap approach reveals a role of the plant wall-associated kinase 1 (WAK1) as a receptor of oligogalacturonides

Abstract

Oligogalacturonides (OGs) released from the plant cell wall are active both as damage-associated molecular patterns (DAMPs) for the activation of the plant immune response and regulators of plant growth and development. Members of the Wall-Associated Kinase (WAK) family are candidate receptors of OGs, due to their ability to bind in vitro these oligosaccharides. Because lethality and redundancy have hampered the study of WAKs by reverse genetics, we have adopted a chimeric receptor approach to elucidate the role of Arabidopsis WAK1. In a test-of-concept study, we first defined the appropriate chimera design and demonstrated that the Arabidopsis pattern recognition receptor (PRR) EFR is amenable to the construction of functional and resistanceconferring chimeric receptors carrying the ectodomain of another Arabidopsis PRR, FLS2. After, we analyzed chimeras derived from EFR and WAK1. Our results show that, upon stimulation with OGs, the WAK1 ectodomain is capable of activating the EFR kinase domain. On the other hand, upon stimulation with the cognate ligand elf18, the EFR ectodomain activates the WAK1 kinase, triggering defense responses that mirror those normally activated by OGs and are effective against fungal and bacterial pathogens. Finally, we show that transgenic plants overexpressing WAK1 are more resistant to Botrytis cinerea.damage-associated molecular patterns | elongation factor tu receptor | pectin-mediated signaling | plant immunity | chimeric receptors

Sequencing of the genus Arabidopsis identifies a complex history of nonbifurcating speciation and abundant trans-specific polymorphism

“…8) and were significantly (FDR-corrected P = 0.006; Online Methods) enriched for genes involved in response to virus, suggesting that selection may indeed have contributed to maintaining some of the ancestral polymorphisms. We identified a total of four virus-response genes with haplotypes shared across all four species: CYCT1;4 (TAIR locus AT4G19600), which is involved in transcriptional activation of viral genes; GRIK1 (TAIR locus AT3G45240), which has a role in the metabolic regulation of virus-infected cells 26,27 ; NIG (TAIR locus AT4G13350), which is involved in nucleocytoplasmic trafficking of viral proteins 28 ; and WAK1 (TAIR locus AT1G21250), which activates an immunity response to damaged cell walls 29 .…”

Arabidopsis MPK3 and MPK6 Play Different Roles in Basal and Oligogalacturonide- or Flagellin-Induced Resistance against Botrytis cinerea

“…Activation of defense responses by OGs increases resistance of Arabidopsis (Arabidopsis thaliana) and grape (Vitis vinifera) leaves against the necrotrophic fungus Botrytis cinerea (Aziz et al, 2004;Ferrari et al, 2007). Recently, the wallassociated kinase WAK1 has been identified as a receptor of OGs (Brutus et al, 2010;De Lorenzo et al, 2011).…”

Arabidopsis PECTIN METHYLESTERASEs Contribute to Immunity against Pseudomonas syringae

“…The elicitor activity of OGs depends on their length and degree of esterification (Osorio et al, 2008;Ferrari et al, 2013). It has been shown that pectic fragments can be perceived by WALL-ASSOCIATED KINASE1 (WAK1) and WAK2 (Kohorn et al, 2009;Brutus et al, 2010). Recognition of OGs activates downstream defense responses including reactive oxygen species production, ethylene production, and callose deposition (Ferrari et al, 2013).…”