Two-Component Signaling Systems in Plants

Two-component systems, consisting of a histidine (His) protein kinase that senses a signalinput and a response regulator that mediates the output, are involved in various signal transductionpathways in many prokaryotes, fungi, slime molds, and plants. While in plants, there also exist morecomplex signaling systems that include a hybrid His kinase, a phosphorelay intermediate and aresponse regulator, which is referred to as multiple step two component systems. Recent studiesindicated that two-component systems play important roles in signal transduction in response toenvironmental stimuli and growth regulators (such as ethylene, cytokinin), light and osmotic stress.