Nitrate modulates stem cell dynamics in Arabidopsis shoot meristems through cytokinins

Significance Plants generate organs throughout their life as a consequence of the maintenance of postembryonic stem cell niches in meristems. The molecular mechanisms controlling stem cell homeostasis and organ emergence in shoot meristems have been well described, but the manner in which environmental signals influence them to generate plasticity is largely unknown. Using the shoot apical meristem of Arabidopsis as a model system, we show that plants can adapt their organogenesis rate to changes in the availability of nitrate in the soil within a few days, thanks to long-range signaling by cytokinin hormone precursors that travel through the plant, are converted to active hormones at the shoot meristem, and modulate the expression of WUSCHEL , a key regulator of stem cell homeostasis.