The biological role of primary and secondary plants metabolites

Abstract

Metabolism consists of closely coordinated series of enzyme-mediated chemical reactions that take place in the plant organism, resulting in the synthesis and use of a wide variety of molecules in the category of carbohydrates, amino acids, fatty acids, nucleotides and polymers derived from them (polysaccharides, proteins, lipids, DNA, RNA, etc.). All these processes are defined as primary metabolism and the respective compounds, which are essential for the survival of the plant, are described as primary metabolites. In addition to the primary metabolites, which play a role in maintaining the viability of the plant (proteins, carbohydrates and lipids), a number of compounds such as terpenes, steroids, anthocyanins, anthraquinones, phenols and polyphenols, which belong to the "secondary metabolism", are also synthesized. Secondary metabolites (SMs) are present only in certain species, often manifesting specificity of organ or tissue, can be identified only at a certain stage of growth and development within a species, or can be activated only during periods of stress caused by the attack. microorganisms or nutrient depletion. Their synthesis seems to have no direct significance for the synthesizing cell, but may be decisive for the development and functioning of the body as a whole. Their synthesis is not a vital part of the gene expression and developmental program, these metabolites are not simple catabolic products, have a diversified structure and can be frequently re-included in metabolic processes. The boundary between primary and secondary metabolism is uncertain, as many primary metabolism intermediates play similar roles in secondary metabolism. Some obscure amino acids are infallibly SMs, while sterols are essential structural compounds of many organisms and should therefore be considered primary metabolites.