Cytokinin-CLAVATA cross-talk is an ancient mechanism regulating shoot meristem homeostasis in land plants.

SignificancePlants grow from their tips. The gametophore (shoot-like organ) tip of the moss is a single cell that performs the same functions as those of multicellular flowering plants, producing the cells that make leaves and regenerating new stem cells to maintain the shoot tip. Several pathways, including CLAVATA and cytokinin hormonal signaling, regulate stem cell abundance in flowering plants and in mosses, although the mechanisms whereby these pathways regulate stem cell abundance and their conservation between these plant lineages is poorly understood.