PEPTIDE PLANT HORMONE, PHYTOSULFOKINE

摘要

Plant cells retain features characteristic of totipotent stem cells. That is, they have the potential to dedifferentiate, re-differentiate, and give rise to all the organs of a new plant. However, relative rates of these cellular processes are strictly dependent on initial cell density, suggesting that cell-to-cell communication is necessary for these processes. Recent biochemical purification studies have demonstrated that phytosulfokine (PSK), a small sulfated peptide, acts as an extracellular ligand involved in the initial step of cellular dedifferentiation, proliferation and re-differentiation. Furthermore, a 120-kD leucine-rich repeat receptor kinase, specifically interacting with PSK, has been purified from plasma membranes using ligand-basedaffinity chromatography. Lines of evidence suggest that this ligand-receptor pair confers competence for dedifferentiation and re-differentiation to individual cells, rather than directly determining cellular fate. In this article, I review what is knownabout PSK signaling.