What is ethylene biosynthesis?

ethylene is a compound of carbon and hydrogen with chemical formula C h _{4 . It is a colorless gas with a sweet odor that the petrochemical industry produces on a large scale for use mainly in the production of plastics. Ethylene is also produced by plants and acts as a hormone that affects key plant processes in many ways. It is unusual that such a small molecule is active as a hormone. The ethylene biosynthesis in plants takes place in response to various stress, including the attack of pests and diseases, drought and tissue damage.}

The effects of ethylene on plants are many and diverse. Its best known effect is to accelerate the maturation of some fruits, such as apples, bananas and tomatoes, but not citrus fruit. Since then, at least the time of ancient Egyptians has been known that some fruit could be ripened faster with bruises; Often it is only necessary to bruise or cut one fruit to accelerate the ripe number stored in the same container. Ethylene has not been identified as the cause of this runtil 1901, and only at the end of the 20th century were details of the process of ethylene biosynthesis in the tissue of plant tissue.

ethylene inhibits the production of flowers in most plants, but promotes seed germination and can affect the development of seedlings in an interesting way, known as "triple response". Seedlings grown in dark conditions and exposed ethylene show a characteristic amplification and shortening of the stem and increased curvature of the apical hook - a structure that protects the growing center at the tip of the stem. Ethylene also promotes the destruction of chlorophyll, the production of pigments called anthocyanins - associated with autumn colors - and aging and release of leaves. Because the compound is gas and - like most hormones - is effective at very low concentrations can easily disperse through plant tissue, and thus the production of this compound can affect others in the vicinity. Ethylene fromPlants can also affect industrial sources and cars.

The starting point for ethylene biosynthesis in plants is methionine, essential amino acid produced in chloroplasts. This responds with adenosine triposphate (ATP) to form S-enenosyl-l-methionine (SAM), also known as S-Adomet, catalyzed by an enzyme called Sam synthetase. Other reactions are converted by SAM into 1-amino-cyclopropan-1-carboxylic acid (ACC), catalyzed by ACC synthase. Finally, ACC reacts with oxygen to produce ethylene, hydrogen cyanide and carbon dioxide, catalyzed by ACC enzyme. Hydrogen cyanide is converted into a harmless compound by another enzyme, so the biosynthesis of ethylene does not release any toxic chemicals.

ACC synthase is produced by plants in response to stress, causes more ACC and then ethylene to be made. Stress may take the form of an attack of insects pests or plant diseases, or this may be caused by environmental factors such as drought, colds or nodfawn. Harmful chemicals can also lead to stress, leading to ethylene production.

Auxin plants, if present in large quantities, stimulates ethylene production. Auxinic herbicides, such as 2,4-dichlorfenoxyoctic acid (2,4-D), mimics the effect of this hormone, causing ethylene production in many plants. While the exact way of effecting these herbicides is not clear, excessive ethylene production seems to play a role in the death of plants in sensitive species.

The purpose of ethylene biosynthesis in plants has been an area of ​​active research since 2011. Due to the wide range of effects of this hormone, it is likely that it has more roles. In the case of seedlings, it seems that it is produced in response to resistance from the soil to developing seedlings and to start the growth of Responns, which help protect the growing center. There is also evidence that it can play a role in disease resistance; Experimental studies suggest that plants lacking ethylene reaction are more susceptible to some diseases.