Abstract
In Arabidopsis, root epidermal cells differentiate either to hair cells or to hairless cells. CAPRICE (CPC) is a positive regulator of the hair-cell differentiation and is preferentially transcribed in the hairless cells. To determine the cis-regulatory elements in the CPC promoter responsible for hairless-cell-specific expression, we examined the promoter activities of truncated CPC promoters. The region between -267 and -336 was revealed to be required for the specific transcription. This region includes two putative Myb-binding sites and when these sites were mutated, the hairless-cell-specific expression was abolished. Two Myb proteins are known to be involved in root-epidermis differentiation; CPC and WEREWOLF (WER). CPC transcription was decreased in the wer mutant. We found that WER could bind to the CPC promoter in yeast. These results suggest that WER directly binds to the CPC promoter and thereby activates its transcription in the hairless cells.
