EFR-Mediated Innate Immune Response in is a Useful Tool for Identification of Novel ERQC Modulators.

Plants offer a simpler and cheaper alternative to mammalian animal models for the study of endoplasmic reticulum glycoprotein folding quality control (ERQC). In particular, the () innate immune response to bacterial peptides provides an easy means of assaying ERQC function in vivo. A number of mutants that are useful to study ERQC have been described in the literature, but only for a subset of these mutants the innate immune response to bacterial elicitors has been measured beyond monitoring plant weight and some physio-pathological parameters related to the plant immune response. In order to probe deeper into the role of ERQC in the plant immune response, we monitored expression levels of the Phosphate-induced 1 ( and reticulin-oxidase homologue ( genes in the ER α-Glu II and the UGGT mutant plants, in response to bacterial peptides elf18 and flg22. The elf18 response was impaired in the but not completely abrogated in the mutant plants, raising the possibility that the latter enzyme is partly dispensable for EF-Tu receptor (EFR) signaling. In the mutant, seedling growth was impaired only by concomitant application of the ER α-Glu II B-DNJ inhibitor at concentrations above 500 nM, compatibly with residual activity in this mutant. The study highlights the need for extending plant innate immune response studies to assays sampling EFR signaling at the molecular level.