L-type lectin receptor kinases in Nicotiana benthamiana and tomato and their role in Phytophthora resistance.

Yan Wang,Rob Weide,Francine Govers,Klaas Bouwmeester

doi:10.1093/jxb/erv379

Abstract

Membrane-bound receptors play crucial roles as sentinels of plant immunity against a large variety of invading microbes. One class of receptors known to be involved in self/non-self-surveillance and plant resistance comprises the L-type lectin receptor kinases (LecRKs). Previously, we reported that several Arabidopsis LecRKs play a role in resistance to Phytophthora pathogens. In this study, we determined whether homologues of these LecRKs from the Solanaceous plants Nicotiana benthamiana and tomato (Solanum lycopersicum) play similar roles in defence against Phytophthora. In genome-wide screenings, a total of 38 (Nb)LecRKs were identified in N. benthamiana and 22 (Sl)LecRKs in tomato, each consisting of both a lectin and a kinase domain. Phylogenetic analysis revealed that, in contrast to Arabidopsis, which has a LecRK family comprising nine clades, Solanaceous species have just five of these nine clades (i.e. IV, VI, VII, VIII, and IX), plus four additional clades that lack Arabidopsis homologues. Several of the Solanaceous LecRKs were selected for functional analysis using virus-induced gene silencing. Infection assays with Phytophthora capsici and Phytophthora infestans on LecRK-silenced plants revealed that N. benthamiana and tomato homologues in clade IX play a role in Phytophthora resistance similar to the two Arabidopsis LecRKs in this clade, suggesting conserved functions of clade IX LecRKs across different plant families. This study provides a first insight into the diversity of Solanaceous LecRKs and their role in plant immunity, and shows the potential of LecRKs for Phytophthora resistance breeding.

Highlights

Plant diseases caused by Phytophthora pathogens are a major constraint to the production of a large variety of Solanaceous crops (Kroon et al, 2012)
Obtained L-type lectin receptor kinase (LecRK) sequences were further analysed by comparative analysis using publicly available expressed sequence tags (ESTs), RNA sequencing (RNA-seq) data derived from Nicotiana benthamiana Genome Page of the University of Sydney and tomato RNAseq data
We investigated whether other NbLecRKs affected cell death triggered by INF1 and whether NbLecRKs play a role in cell death triggered by two other Phytophthora elicitors, CRN2 and NPP1

Summary

Introduction

Plant diseases caused by Phytophthora pathogens are a major constraint to the production of a large variety of Solanaceous crops (Kroon et al, 2012). Breeding for Phytophthora resistance has been focused largely on the introgression of resistance (R) genes encoding the intracellular nucleotide-binding leucine-rich repeat. Receptors (NLRs), which mediate effector-triggered immunity (ETI) upon recognition of cognate effectors (Vleeshouwers et al, 2011). Since Phytophthora pathogens can quickly adapt, NLR-mediated resistance is often not durable. New races emerge that have inactivated or modified effector genes and can circumvent R gene recognition (Vleeshouwers et al, 2011; Kasuga and Gijzen, 2013)

Methods

Results

Conclusion