Looking BAK again: Is an old acquaintance of innate immunity involved in the detection of herbivores?

The membrane-based receptor-like kinase BAK1 has been reported to interact with a number of other membrane-based receptors to contribute to a variety of signaling responses to exogenous and endogenous cues. These include brassinosteroid hormones as well as conserved microbe-derived and endogenous patterns. More recently, several lines of evidence have been reported to expand this concept also to the detection and deterrence of insect herbivores. We hereby present results that further support this hypothesis as they show that in Arabidopsis thaliana, herbivore oral secretions trigger two hallmark responses of plant innate immunity and that these responses are significantly reduced in plants that lack functional BAK1 receptors.