Ethylene stimulation

Ethylene is a colorless, flammable gas with a boiling point of-104 °C. More than 22 billion kilograms of ethylene are produced annually in the United States, making it one of the top five industrial chemicals. The manufacture of plastics (polyethylene is the most common example) consumes 75% of this output, and much of the rest is used to make antifreeze. Because ethylene stimulates the breakdown of cell walls. It Is used commercially to hasten the ripening of fruit, particularly bananas. 

The ripening of nonclimacteric fruits is usually considered as a process that as a whole does not require ethylene. Nevertheless, endogenous ethylene is involved at some steps of development of these fruits. In general, chlorophyll degradation in nonclimacteric fruits is believed to be ethylene stimulated, whereas the synthesis of pigments can depend on ethylene action or not. ... 

El-Kereamy, A. et al., Exogenous ethylene stimulates the long term expression of genes related to the anthocyanin synthesis in grape berries. Physiol. Plant 119, 1, 2003. 

Davies, K.M., Hobson, G.E. Grierson, D. (1988). Silver ions inhibit the ethylene-stimulated production of ripening-related mRNAs in tomato. Plant, Cell and Environment 11, 729-38. 

Maunders, M.J., Holdsworth, M.J., Slater, A., Knapp, J.E., Bird, C.R., Schuch, W. Grierson, D. (1987). Ethylene stimulates the accumulation of ripening-related mRNAs in tomatoes. Plant, Cell and Environment 10, 177-87. 

Ethylene as a stimulator of growth and development. The most observed actions of ethylene on growing plants involves growth inhibition, or acceleration of senescence. These actions are especially evident in the antagonism or opposition of ethylene to auxins, gibberellins and cytokinins (27), as already outlined above. Actually ethylene stimulates growth in many types of cells, especially in water plants (Table II). When ethylene acts to stimulate cell elongation, as in water plants, auxins and CC>2 enhance the ethylene effect (38,39). This interaction is the reverse of that observed on land plants wherein ethylene opposes the effects of auxin, GA3 and cytokinins. 

Figure 1. Effect of ethylene on respiration of climacteric and nonclimacteric fruit. Ethylene causes greatest response in climacteric fruit when applied to mature fruit prior to the climacteric rise. In nonclimacteric fruit high concentrations of ethylene stimulate respiration for short time periods. This stimulation is observed at any time upon application of ethylene (3).

Ethylene is a hydrocarbon plant hormone that comes from the methionyl moiety of S-adenosylmethionine. Ethylene stimulates fruit n 2 ripening and the aging of flowers, and it inhibits seedling growth. It also redirects auxin transport (another plant hormone) to promote transverse, rather than longitudinal, growth of plants. 

I. Subthreshold Plasma Ignition of Ethylene Stimulated by Excited Molecules Effect of NO... 

Finally, two case studies were presented briefly to give a better feel for what research and development activities are all about. Vinyl chloride monomer production showed how the availability of cheap raw materials (e.g. ethylene) stimulated the development of processes to utilize these, and how continuing research and development led to new, even better processes. It also emphasized the importance of reading the chemical literature. Development and production of CFC replacements demonstrated what an enormous R D effort can achieve in such a short time. Great emphasis on research and development is a key characteristic of high technology industries like the chemical industry. 

Ethylene increases rapidly but differently in the case of climacteric fruits. The maximum values for some fruits are given in Table 18.35. However, nonclimacteric fruits produce only a little ethylene (Table 18.35). This gaseous compound increases membrane permeability and thereby probably accelerates metabolism and fruit ripening. With mango fruits, for example, it has been demonstrated that before the climacteric stage, ethylene stimulates oxidative and hydrolytic enzymes (catalase, peroxidase and amylase) and inactivates inhibitors of these enzymes. 

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