Endosomal trafficking and signaling in plant defense responses

• Leucine-rich-repeat receptors mediate defense responses in several plant systems.
• Endocytosis has been shown to be involved in this process.
• Here we summarize recent findings concerning endosomal trafficking, in particular during defense.
• We also address the concept of plant endosomal signaling.

Plant defense responses are initiated by ligand–receptor recognition. The receptor may contain a motif for endocytosis and endocytosis is important for defense signaling in some cases.Recently, endosomal trafficking during defense has begun to be elucidated. In some cases, defense receptors are internalized into early endosomes, recycled back to the plasma membrane (PM) on recycling endosomes, and targeted for degradation via the late endosome pathway in an ESCRT dependent manner.Endosomal signaling has been proposed for several receptors. Defense receptors have been shown to reside on endosomes during the signaling time window. Increasing the endosomal presence of a receptor can cause a concomitant increase in signaling, while abolishing the formation of endosomes after the receptor has already been internalized can cause signaling attenuation.