Abstract
The MYB gene CAPRICE (CPC), one of the regulators of epidermal cell differentiation, represses the expression of the homeodomain-leucine zipper gene GLABRA2 (GL2) in root-hair cells. Analysis of CPC::CPC:GFP transgenic plants indicated that the CPC protein moves from hairless cells to root-hair cells. We expressed CPC ectopically using promoters specific for other cell-types, and showed that CPC also moved from root-hair cells to hairless cells, but not from stele to epidermis. We identified a sequence in the CPC protein which is responsible for cell-to-cell movement. Using yeast two-hybrid screening, we isolated CPC-interacting factors which might regulate the cell-to-cell movement of CPC.
We also analyzed epidermis-specific bHLH genes in Arabidopsis and demonstrated that GLABRA3 and ENHANCER OF GLABRA3 proteins moved from root-hair cells to hairless cells, where they activated GL2 expression. Our current knowledge of the regulatory network for cell-to-cell movement of proteins in Arabidopsis epidermis will be presented.
