*2.4.1 Introduction*

The important hormone ethylene controls and mediates intricate cycles in plants that affect their growth and development as well as their ability to survive throughout their life cycle. The capacity of ethylene to ripen fruits and cause senescence is its primary use and area of scientific study. The potential to accelerate the ripening of fruits where ethylene is the primary hormone, such as tomato and banana fruits, has been the main focus for food biotechnologists. By regulating the manufacture of the ethylene hormone, food biotechnologists hope to be able to control the ripening of fruit [19].

We must first comprehend how ethylene is secreted in the tissues of a plant in order to comprehend its function. Two stages make up the metabolic process that produces ethylene [20].

It begins with a substance called SAM (S-adenosyl-L-methionine). The enzyme ACS aids in the conversion of SAM into ACC (ACC synthase). ACO is an enzyme that converts ACC to ethylene (ACC oxidase) [21].

It is important to realise that the enzymes ACS and ACO are both released by various gene coding families in synchrony with one another when conditions like drought, flood, wound, exerting pressure from the outside, and pathogen assault occur [22].
