Ethylene (C2H4, also known as ethene) is a gaseous organic compound that is the simplest of the alkene chemical structures (alkenes contain a carbon-carbon double bond). Ethylene is the most commercially produced organic compound in the world and is used in many industrial applications. Ethylene is also a gaseous plant hormone.
The hormone effects of ethylene on general plant growth were first noted in 1864 when leakage from gas street lighting systems caused stunting and deformation of nearby plants. In 1901 Neljubow identified the active component of the gas to be ethylene but it was not until 1934 that Gane identified that plants could synthesise ethylene and in 1935 Crocker proposed ethylene to be the hormone responsible for fruit ripening and senescence of vegetative tissues.
Research has since demonstrated that ethylene has an important role in many plant development processes, including seed germination, vegetative growth, leaf abscission, flowering, senescence and fruit ripening. Ethylene also plays a role in response to water stress, chilling and mechanical injury.