The lexA(DBD)::CIBN hemidriver contains the DNA-binding domain from the Escherichia coli lexA gene (ECOGENE:EG10533) fused via a flexible linker to an N-terminal portion (amino acids 1-171) of Arabidopsis thaliana CIB1 (TAIR:130033). lexA(DBD)::CIBN forms one half of a light-regulated split lexA system when combined in vivo with a hemidriver containing a transcriptional activation domain fused to the Arabidopsis thaliana CRY2 gene (TAIR:28374). Upon illumination with blue light, CRY2 undergoes a conformational change and can bind the CIBN peptide, bringing the two hemidrivers together and reconstituting a functional transcriptional activator that can drive transcription of a downstream gene of interest. Since transcription is only activated at the intersection of the expression patterns of the two hemidrivers and upon activation by light, this system can be used to drive expression in a restricted pattern. The reconstituted transcriptional activator binds specifically to the lexAop regulatory sequence due to the presence of the lexA DNA-binding domain (FBrf0229642).