BIOMOLECULES AND ENZYMES

Detailed explanation-1: -Primarily, aging and the dropping of leaves are controlled by the plant growth hormone named abscisic acid (ABA). It also helps to control the dormancy of the seeds and to sustain the plant in adverse conditions. Ethylene is a gaseous hormone which helps in the ripening of fruits.

Detailed explanation-2: -For example, abscisic acid (ABA) is thought to be one of the phytohormones that promote leaf senescence (11, 12). Specifically, both an up-regulation of genes associated with ABA signaling and a dramatic increase in endogenous ABA levels can be observed in many plants during leaf senescence (13).

Detailed explanation-3: -Programmed senescence seems to be heavily influenced by plant hormones. The hormones abscisic acid, ethylene, jasmonic acid and salicylic acid are accepted by most scientists as promoters of senescence, but at least one source lists gibberellins, brassinosteroids and strigolactone as also being involved.

Detailed explanation-4: -It has an essential role in multiple physiological processes of plants, such as stomatal closure, cuticular wax accumulation, leaf senescence, bud dormancy, seed germination, osmotic regulation, and growth inhibition among many others.