ROOT DEVELOPMENT - NEW MEANINGS FOR ROOT CANALS

During Arabidopsis root development, a radial pattern of tissues is ex tended by the meristem, These tissues form continuous layers and recen t data suggest that tissue continuity is instrumental for constraining the direction of signaling in a process termed channeling. In the gro und tissue, fate-determining signals originate from contiguous cells o f the same layer, possibly due to specific symplastic connections, Mut ant analysis supports the hypothesis that vascular tissue continuity m ay facilitate and depend on the directional transport of a vascular fa te-determining signal, possibly the phytohormone auxin.