Probable component of a transcriptional corepressor complex that acts specifically in the karrikin pathway (PubMed:26754282). Controls seedling growth redundantly with SMAX1, but is not involved in leaf morphology, shoot branching or germination control (PubMed:26754282). Interacts probably with TPL/TPR in an EAR-motif dependent manner. Expressed in seedlings and leaves. Detected in roots and axillary branches. Up-regulated by karrikins and strigolactone treatments. No visible phenotype under continuous red light (PubMed:26754282). Smax1 and smxl2 double mutants have substential reduction in hypocotyl elongation (PubMed:26754282). Belongs to the ClpA/ClpB family.