Cytokinin sensing systems using microorganisms.

The cytokinin class of plant hormones is perceived by transmembrane His-kinases (His-kinases) of the two-component system, otherwise known as the His-Asp phosphorelay system. When cytokinin receptors perceive cytokinins, they are autophosphorylated at a conserved His residue. The phosphoryl group is then transferred to downstream components of the His-Asp phosphorelay system. When the gene for a cytokinin receptor is introduced into yeast or Escherichia coli, the corresponding receptor feeds the phosphoryl group to the phosphorelay system of the host, in a cytokinin-dependent manner. Therefore, these microorganisms can be used as convenient cytokinin sensors, and can also be used to understand the properties of cytokinin-receptors. Furthermore, they may be used to screen for cytokinin agonists and antagonists, which would potentially be useful to regulate the growth of crops.