A mobile transcription factor

Location, location, location—the mantra of real estate also holds true for plant development, where the fate of a plant cell depends largely on its position rather than its lineage. In the core of a growing root, cells learn their position from their neighbors through the actions of a transcription factor that travels between cell layers, according to a study conducted at New York University, NY. This protein is novel because of its dual function: it both induces cell division and signals cell identity.Philip Benfey and colleagues report that the SHORT-ROOT protein (SHR) is made only in the innermost layer of the Arabidopsis root, but it travels to the adjacent layer. There, it stimulates cell division by turning on a growth-promoting gene called SCARECROW, and it helps establish the identity of endodermal cells,...