Updated project metadata. Karrikins (KARs) are a class of butenolide molecules found in smoke. KARs regulate many aspects of plant development and environmental responses, including Seed germination, hypocotyl elongation, leaf shape, root development, and resistance to drought, salt, and heat stress. The transcriptional repressor proteins SUPPRESSOR OF MAX2 1 (SMAX1) and SMAX1-like2 (SMXL2) integrate karrikin signaling by repressing gene expression through direct binding to promoters or through inhibiting activities of transcription factors. To elucidate the mechanism by which SMAX1 and SMXL2 mediate KAR signaling, we performed immunoprecipitation followed by mass spectrometry (IP-MS) analysis and identified peptides in transgenic seedlings that overexpress GFP, SMAX1-GFP, and SMXL2-GFP, respectively.