EHD2 inhibits signaling of leucine rich repeat receptor-like proteins.

Leucine-rich-repeat receptor protein (LRR-RLPs) and LRR-RLKs have been linked with signaling and defense responses in plants. EIX (ethylene-inducing xylanase) triggers a defense response via the LeEix2 receptor, while bacterial flagellin triggers plant innate immunity via the FLS2 receptor. Endocytosis has been suggested to be crucial for the process in both cases. Recently, we showed that the EIX elicitor triggers internalization of the LeEix2 receptor. Additionally, we demonstrate that plant EHD2 is an important factor in the internalization and regulation of the induction of plant immunity in the case of EIX/LeEix2 but does not appear to be involved in the flg/FLS2 system. Here we show that EHD2 is also involved in the signaling of the Cf4 and Cf9 receptors, causing inhibition of hypersensitive response (HR) and ethylene biosynthesis upon overexpression of EHD2. Our results suggest that different endocytosis pathways are involved in the induction of plant defense responses.