The Lectin Receptor Kinase-VI.2 Is Required for Priming and Positively Regulates Arabidopsis Pattern-Triggered Immunity

Abstract

Plant cells can be sensitized toward a subsequent pathogen attack by avirulent pathogens or by chemicals such as b-aminobutyric acid (BABA). This process is called priming. Using a reverse genetic approach in Arabidopsis thaliana, we demonstrate that the BABA-responsive L-type lectin receptor kinase-VI.2 (LecRK-VI.2) contributes to disease resistance against the hemibiotrophic Pseudomonas syringae and the necrotrophic Pectobacterium carotovorum bacteria. Accordingly, LecRK-VI.2 mRNA levels increased after bacterial inoculation or treatments with microbe-associated molecular patterns (MAMPs). We also show that LecRK-VI.2 is required for full activation of pattern-triggered immunity (PTI); notably, lecrk-VI.2-1 mutants show reduced upregulation of PTI marker genes, impaired callose deposition, and defective stomatal closure. Overexpression studies combined with genome-wide microarray analyses indicate that LecRK-VI.2 positively regulates the PTI response. LecRK-VI.2 is demonstrated to act upstream of mitogen-activated protein kinase signaling, but independently of reactive oxygen production and BOTRYTIS-INDUCED KINASE1 phosphorylation. In addition, complex formation between the MAMP receptor FLAGELLIN SENSING2 and its signaling partner BRASSINOSTEROID INSENSITIVE1-ASSOCIATED KINASE1 is observed in flg22-treated lecrk-VI.2-1 mutants. LecRK-VI.2 is also required for full BABA-induced resistance and priming of PTI. Our work identifies LecRK-VI.2 as a novel mediator of the Arabidopsis PTI response and provides insight into molecular mechanisms governing priming.

The Arabidopsis LECTIN RECEPTOR KINASE-VI.2 is a functional protein kinase and is dispensable for basal resistance toBotrytis cinerea

“…8 In this report we demonstrate that LecRKVI.2 possesses a functional kinase domain. PTI, demonstrated a wild type resistance response to the necrotroph B. cinerea (Fig.…”

“…8 Here we suggest that LecRK-VI.2 possesses a functional kinase domain that is able to auto-phosphorylate. In addition, resistance to the necrotrophic Keywords: Arabidopsis thaliana, lectin receptor kinase, innate immunity, protein kinase, botrytis cinerea, chitin fungal pathogen B. cinerea and expression of PTI-responsive genes after chitin treatment were at wild-type levels in a lecrk-VI.2-1 T-DNA insertion mutant.…”

“…7 Recently, we demonstrated that the L-type lectin receptor kinase VI.2 (LecRK-VI.2) positively regulates Arabidopsis bacteria-mediated PTI. 8 Here we suggest that LecRK-VI.2 possesses a functional kinase domain that is able to auto-phosphorylate. In addition, resistance to the necrotrophic Fig.…”

Disease resistance toPectobacterium carotovorumis negatively modulated by the Arabidopsis Lectin Receptor Kinase LecRK-V.5

“…6 Moreover, a recent study using mutant and overexpression lines of LecRK-VI.2 suggested the importance of stomatal immunity in resistance against both Pcc and Pst DC3000 infection. 9 Necrotrophic and hemi-biotrophic pathogens have different lifestyles that induce a different set of defense responses in Arabidopsis. 7 However, as the first barrier against microbes, stomatal immunity is important for plant defense against pathogenic and non-pathogenic bacteria that penetrate into leaves via natural opening.…”

Bound by Fate: The Role of Reactive Oxygen Species in Receptor-Like Kinase Signaling

“…However, FLS2-dependent activation of RBOHD is not required for the activation of MPK3 and MPK6 in response to bacterial pathogens (Xu et al, 2014). By contrast, the Malectin-like/LRR-RLK IMPAIRED OOMYCETE SUSCEPTIBILITY1 (IOS1; Yeh et al, 2016), a component of the FLS2 receptor complex, and LecRK-VI.2 (Singh et al, 2012) are required for the activation of MPK3 and MPK6 but not for the ROS burst. While the identities of all complexes involving IOS1 remain to be elucidated, it is likely that IOS1 serves as a common node leading to MAPK activation.…”