Abstract: | The gaseous hormone ethylene is an important regulator of plantgrowth and development. Using a simple response of etiolatedseedlings to ethylene as a genetic screen, genes involved inethylene signal transduction have been identified in Arabidopsis.Analysis of two of these genes that have been cloned revealsthat ethylene signalling involves a combination of a protein(ETR1) with similarity to bacterial histidine kinases and aprotein (CTR1) with similarity to Raf-1, a protein kinase involvedin multiple signalling cascades in eukaryotic cells. Severallines of investigation provide compelling evidence that ETR1encodes an ethylene receptor. For the first time there is aglimpse of the molecular circuitry underlying the signal transductionpathway for a plant hormone. Key words: Ethylene, plant growth, plant development, regulation, signal transduction, Arabidopsis |