EVERYDAY SCIENCE

Detailed explanation-1: -Ethylene is a plant hormone which is present in gaseous form. It is formed by the breakdown of methionine, which is in all cells. Thus, methionine is called as the precursor of ethylene hormone.

Detailed explanation-2: -This is because methionine is the immediate precursor of S-adenosylmethionine (AdoMet), which plays numerous roles of being the major methyl-group donor in transmethylation reactions and an intermediate in the biosynthesis of polyamines and of the phytohormone ethylene.

Detailed explanation-3: -The gaseous hormone ethylene plays a key role in plant growth and development, and it is a major regulator of stress responses. It inhibits vegetative growth by restricting cell elongation, mainly through cross-talk with auxins.

Detailed explanation-4: -First, sulfur-containing metabolite, methionine, is a precursor of ethylene and is a rate limiting metabolite for ethylene synthesis; the methionine cycle contributes to both sulfur and ethylene metabolism.

Detailed explanation-5: -Despite their diverse chemical structures, most of the known plant hormones are derived from three main types of metabolic precursors: amino acids, isoprenoid compounds, and lipids. The amino acids tryptophan and methionine serve as precursors for IAA (indole-3-acetic acid) and ethylene, respectively.