Plant stem cell niches: from signalling to execution

The shoot and root meristems contain small populations of stem cells that constantly renew themselves while providing precursor cells to build all other plant tissues and organs. Cell renewal, growth and differentiation in the meristems are co-ordinated by networks of transcription factors and intercellular signals. The past two years have revealed how auxin and cytokinin signals are integrated with each other and with regulatory genes in the shoot and root meristems. Small RNAs have also emerged as novel intercellular signals. Downstream of meristem regulatory genes, links have been made to cell division control and chromatin function. Protection of genome integrity, partly through programmed cell death after DNA damage, has recently been revealed as a specialised function in plant stem cells.

Research highlights▶ Advances in signalling and gene regulation in plant stem cell niches are reviewed. ▶ The integration of auxin and cytokinin signals in the meristems has been clarified. ▶ Small RNAs have emerged as novel intercellular signals. ▶ Meristem regulators control cell division and hormone responses. ▶ Chromatin modification and genome integrity are key downstream targets.