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Ethylene and ethylene biosynthesis. The only hormone as a gas. All living and non-living organism can generates ethylene, All materials under burning produces ethylene.
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Ethylene and ethylene biosynthesis • The only hormone as a gas. • All living and non-living organism can generates ethylene, All materials under burning produces ethylene. • All fruits produces minute quantities of ethylene during development, but climacteric fruits produce much larger amounts ethylene during ripening than non-climacteric fruits. • This difference between the two classes is further exemplified by the internal ethylene concentration. • Ethylene as low as 0.1-1 µL/L for 1 day is sufficient to hasten full ripening of climacteric fruit.
Mode of action • Ethylene is a plant hormone that acts in concert with other plant hormones (auxins,gibberellins,kenitin and ABA). • Ethylene induced ripening • flower fading • Senescence • chlorophyll loss • Abscission • physiological disorders • epinasty, and various deterioration of horticultural commodities during transport and storage.
Atmospheric ethylene • Rural area 1-5 µL/L • Major city 30-700 µL/L • Supermarket 17-35 µL/L • Wholesale market 60 µL/L • Flower wholesale market 13 µL/L • Greenhouse packing 0.1-2 µL/L
Ethylene synthesis (1) • It has been hypothesized that that two different systems regulating the production of ethylene. • System I, opening in vegetative tissues and in both climacteric and non-climacteric fruits, seems responsible for basal and wound-induced ethylene production. • System II, is potentially responsible for the rapid increase in ethylene production during the ripening of climacteric fruits. In mature climacteric fruits, ethylene production is autostimulated, and inhibitors of ethylene action completely block ethylene production and fruit ripening. Autocatalytic ethylene production requires up
Ethylene synthesis (2) • Regulation by ethylene of ACC-synthesis and EFA, the enzymes involved in the rate-limiting reactions in ethylene biosynthesis. • ACC-synthesis, which catalyzes the formation 1-aminocyclopropan-1-carboxylic acid from S-adenosyl-l-methionine, is the rate-limiting enzyme in ethylene biosynthesis. • EFA-synthesis, an oxidative enzyme convert ACC to ethylene.