Interactions of the karrikin signaling pathway with phytohormones and environmental signals in plants

<p>Karrikins (KARs), a class of butenolide compounds discovered in the smoke of burned vegetation, can mimic an unidentified phytohormone to regulate plant development and responses to environmental cues. The KAR signaling pathway is mediated by the 26S proteasome. Upon perception of KARs, the receptor of KARs, KARRIKIN INSENSITIVE 2 (KAI2), recruits the F-box protein, MORE AXILLARY GROWTH 2 (MAX2), and the repressor proteins, SUPPRESSOR OF MAX2 1 (SMAX1) and SMAX1-LIKE 2 (SMXL2), leading to the degradation of SMAX1 and SMXL2, which then reprograms the transcription of the KAR-responsive genes. This review focuses on the latest research progress regarding KAR signaling transduction, the identification of KAI2 ligands, and the crosstalk between KAR signaling, plant hormones, and environmental cues, providing new insights for future studies and applications in agriculture.</p>