KAI2 can do: Karrikin Receptor Function in Plant Development and Response to Abiotic and Biotic Factors.

The α/β hydrolase KARRIKIN INSENSITIVE 2 (KAI2) functions as a receptor for a yet undiscovered phytohormone, provisionally termed KAI2-ligand (KL). In addition, it perceives karrikin, a butenolide compound found in the smoke of burnt plant material. KAI2-mediated signalling is involved in regulating seed germination and in shaping seedling and adult plant morphology, both above and below ground. It also governs responses to various abiotic stimuli and stresses and shapes biotic interactions. KAI2-signalling is being linked to an elaborate cross-talk with other phytohormone pathways such as auxin, gibberellin, abscisic acid, ethylene, and salicylic acid signalling, in addition to light and nutrient starvation signalling. Further connections will likely be revealed in the future. This article summarizes recent advances in unravelling the function of KAI2-mediated signalling and its interaction with other signalling pathways.