The glutamate receptor-like GLR2.7 modulates insect egg-induced defense responses in Arabidopsis

Upon perception of insect eggs, Arabidopsis thaliana activates a generic immune response that culminates in cell death (hypersensitive-like response (HR-like)). While this response can subsequently impact egg survival, the molecular mechanisms are poorly understood. Through a genome-wide association study (GWAS), we identified the amino acid-gated calcium channel GLUTAMATE-LIKE RECEPTOR2.7 (GLR2.7) as an important gene controlling the extent of HR-like and accumulation of salicylic acid (SA) in response to egg extract of Pieris brassicae. Analysis of natural polymorphisms showed that two major haplotypes segregate at the species-wide level and suggests that balancing selection acts at this locus. Insect oviposition triggered a long-lasting localized cytosolic calcium accumulation that depended on GLR2.7 and was linked with egg-associated glutamate (Glu). We propose that Glu-activated GLR2.7 is involved in egg perception and early immune responses.