<b>Molecular genetic characterization of</b><b>CASEIN KINASE 1-LIKE 12</b><b>in</b><i><b>Arabidopsis</b></i>

The CASEIN KINASE 1 (CK1) family plays diverse roles in the development, physiology, and disease in eukaryotes. In Arabidopsis thaliana, the CASEIN KINASE 1-LIKE (CKL) family has 13 members, but to date, the roles of these kinases remain largely unclear. Here, we characterize several insertion mutants, finding that CKL12 may contribute to hypocotyl and primary root growth. Differential effects of insertions at various parts of the gene suggest that the 3′ end of the transcript may be important for CKL12 function. We provide evidence that CKL12 may be a transcriptional target of brassinosteroid (BR) signaling. The CKL12 promoter contains in vitro binding sites for BR-related transcription factors. Knock-down of these transcription factors using RNA interference reduces CKL12 transcript. Together, these data suggest that CKL12 may act downstream of BR signaling to regulate seedling growth.