Abstract
CAPRICE (CPC) encodes a small protein with a R3 MYB motif and promotes root-hair cell differentiation in Arabidopsis (Wada et al., 1997). We found four additional CPC-like Myb sequences. Plant lines that overexpress these four genes had a reduction in the number of trichomes and an increase in the number of root-hairs, which is similar to an overexpressor of CPC. We also made double and triple mutants to clarify the function of each gene. These results suggest that the CPC-like R3 MYB genes cooperatively regulate epidermal cell differentiation. Unlike CPC, CPC-like Myb GFP fusion proteins did not move from cell-to-cell. Promoter-GUS analyses indicated that these CPC homolog were specifically expressed in epidermal cells, some of them were in stomate guard cells. Notably, the CPL3 gene alone has pleiotropic effects on stomata guard cell distribution, flowering development, and epidermal cell size through the regulation of endoreduplication.
