A fundamental question in developmental biology is how cells communicate positional information to pattern the tissues of an organ. Here, the patterning of a plant's xylem tubes, which transport water and solutes from root to shoot, is studied. A new bidirectional signalling pathway is discovered, whereby a transcription factor moves from cell to cell in one direction, and microRNAs move in the other direction. The result is a differential distribution of target mRNA in the vascular cylinder, determining xylem cell types.
- Annelie Carlsbecker
- Ji-Young Lee
- Philip N. Benfey
