Acts as a receptor of SCOOP peptides from Brassicaceae plants regulating multiple processing including plant growth, development and stress responses. Perception of SCOOP peptides induces the association of MIK2 with the coreceptors BAK1/SERK3 and SERK4 and relays the signaling through the activation of receptor-like cytosolic kinases (RLCKs) BIK1 and PBL1. Also able to detect SCOOP-like proteins (SCOOPL) present in fungal Fusarium spp. and bacterial Comamonadaceae to elicit various immune responses, including growth inhibition, ROS production, calcium Ca(2+) influx, MAPK activation and MYB51 promoter activation in roots, thus being required for resistance to several root pathogens. Involved in the pollen tube perception of the female signal. Required to trigger defense responses toward generalist herbivores such as Spodoptera littoralis, probably via the activation of jasmonate and indole glucosinolate biosynthesis