Plant Phenolics: Their Biosynthesis, Regulation, Evolutionary Significance, and Role in Senescence

Abstract

Phenolics are one of the most abundant groups of secondary metabolites found throughout the plant kingdom. Phenolic compounds are widely distributed in plant tissues, particularly contributing to color, flavor, taste, and astringency to fruits. Phenolics are aromatic benzene ring compounds with one or more hydroxyl groups attached to it. Phenolics constitute most likely the largest group of plant secondary metabolites, varying in size from a simple structure with an aromatic ring to complex ones such as lignins. Most phenolic compounds are thought to be by-products of the metabolism of the aromatic amino acid phenylalanine. Phenolics are considered to play a vital role in the evolution of plants by providing an adaptive advantage to cope up with the changing environments. Furthermore, they are believed to be involved in leaf and petal senescence. Change in the leaf or petal color during senescence is also due to anthocyanin pigments, a kind of plant phenolics.