Overexpression of the histidine kinase CKI1 results into cytokinin-independent activation of two-component signaling (TCS) pathway and cytokinin-like response in hypocotyl explants. CKI1 was found to be involved in the female gametophyte development and procambium activity during vascular tissue formation. Recent data suggest that regulation of CKI1 expression might contribute to the regulation of TCS. We used forward genetics approach to identify the factors regulating the activity of CKI1 promotor. Transgenic lines carrying ProCKI1:uidA construct were mutated by EMS and M2 seedlings were screened for changes in the GUS pattern using automated microscopy (dotSlide) system. The level of CKI1 gene expression in mutants was tested using qRT-PCR and the more detailed analysis of selected mutants is in the progress. Phenotype of these mutants and the influence of spatiotemporal changes in CKI1 expression on the TCS will be analyzed and affected genes will be identified using map-based cloning.