NationMaster - Encyclopedia: Ethylene (plant hormone)

Ethylene (or Ethene) functions as a plant hormone in plants. It stimulates the ripening of fruit, the opening of flowers, and the abscission of leaves. Its biosynthesis starts from methionine with 1-aminocyclopropane-1-carboxylic acid (ACC) as a key intermediate.

Location, Characteristics and Occasions for Synthesis Induction

Directly induced by high levels of Auxin
Found in germinating seeds
Induced by root flooding
Induced by drought
Synthesized in nodes of stems
Synthesized in tissues of ripening fruits
Synthesized in response to shoot environmental, pest, or disease stress
Synthesized in senescent leaves and flowers
Rapidly diffuses
Inhibiting effects of Ethylene on shoot growth (more specifically on stem elongation) reduced in the presence of light. Also Ethylene levels are decreased by light
Released in mature cells when they do not have enough minerals and water to support both themselves and any dependent cells
Released by all cells when they are experiencing conditions which would normally cause a mature shoot cell to produce Ethylene

Effects

Stimulates leaf and flower senescence
Induces leaf abscission mainly in older versus younger leaves.
Induces seed germination
Induces root hair growth – this increases the efficiency of water and mineral absorption
Stimulates Epinasty – leaf petiole grows out, leaf hangs down and curls into itself
Stimulates fruit ripening
Induces the growth of adventitious roots during flooding
Usually inhibits growth - just shoot growth
Affects neighboring individuals
Disease/wounding resistance
Triple response when applied to seedlings – root ? and shoot growth inhibition and pronounced hypocotyl hook bending
Inhibits stem swelling ? (Contradictory to the finding below – contradictory sources)
Stimulates cell broadening (and lateral root growth)
Interference with Auxin transport (when hormone levels are increasing)
Directly or indirectly induces Auxin at high levels
(From Theory II of plant hormones) Inhibits the rate of metabolism of cells in the shoot (who are not already at their lowest metabolism rates) in response to an decrease in the levels minerals and/or water

Plant hormones	edit (http://en.wikipedia.org/w/wiki.phtml?title=Template:Plant_hormones&action=edit)
Auxins - Cytokinins - Ethylene - Gibberellins - Abscisic acid - Brassinosteroids - Jasmonates - Salicylic acid

Categories: Plant hormones

Results from FactBites:

Ethylene (422 words)
	Ethylene, unlike the rest of the plant hormone compounds is a gaseous hormone.
	It is produced in all higher plants and is usually associated with fruit ripening and the tripple response (Arteca, 1996; Mauseth, 1991; Raven, 1992; Salisbury and Ross, 1992).
	Ethylene is produced in all higher plants and is produced from methionine in essentially all tissues.

Definition of Plant hormone (632 words)
	Plant hormones (or plant growth regulators, or PGRs) are internally secreted chemicals in plants that are used for regulating their growth.
	The first assumption in both theories is that plants are interested in growing larger during the vegetative period of their life and this growth requires both good environmental conditions and an amount of the four basic nutrient groups that exceeds that needed to keep the plant at its current size.
	Stress hormones, in contrast, may be made in mature cells that are faced with a scarcity of nutrients and to a much lesser extent in young and meristematic cells faced with the same scarcity.

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