Phenolic Compounds: Introduction (original) (raw)

Plant Phenolics: A Biochemical and Physiological Perspective

Cheynier/Recent Advances in Polyphenol Research, 2012

The plant polyphenols are a very heterogeneous group, some universally and others widely distributed among plants, and often present in surprisingly high concentrations. During the evolutionary adaptation of plants to land, the biosynthesis of different phenolics classes in plants has evolved in response to changes in the external environment. Besides a bulk of phenolic substances having cell wall structural roles, a great diversity of non-structural constituents was also formed, having such various roles as defending plants, establishing flower colour and contributing substantially to certain flavours. The accumulation of phenolics in plant tissues is considered a common adaptive response of plants to adverse environmental conditions, therefore increasing evolutionary fitness. In addition, these secondary metabolites may still be physiologically important as a means of channelling and storing carbon compounds, accumulated from photosynthesis, during periods when nitrogen is limiting or whenever leaf growth is curtailed.

Response of Phenylpropanoid Pathway and the Role of Polyphenols in Plants under Abiotic Stress

Molecules

Phenolic compounds are an important class of plant secondary metabolites which play crucial physiological roles throughout the plant life cycle. Phenolics are produced under optimal and suboptimal conditions in plants and play key roles in developmental processes like cell division, hormonal regulation, photosynthetic activity, nutrient mineralization, and reproduction. Plants exhibit increased synthesis of polyphenols such as phenolic acids and flavonoids under abiotic stress conditions, which help the plant to cope with environmental constraints. Phenylpropanoid biosynthetic pathway is activated under abiotic stress conditions (drought, heavy metal, salinity, high/low temperature, and ultraviolet radiations) resulting in accumulation of various phenolic compounds which, among other roles, have the potential to scavenge harmful reactive oxygen species. Deepening the research focuses on the phenolic responses to abiotic stress is of great interest for the scientific community. In th...

Plant Physiological Aspects of Phenolic Compounds

Plant Physiological Aspects of Phenolic Compounds, 2019

MicroRNAs (miRNAs) are noncoding RNAs that play an important role in the regulation of the genetic expression in animals and plants by targeting mRNAs for cleavage or translational repression. Several miRNAs regulate the plant development, the metabolism, and the responses to biotic and abiotic stresses. Characterization of an miRNA has helped to show its role in fine tuning the mechanisms of posttranscriptional gene regulation. Although there is a lot of information related to miRNA regulation of some processes, the role of miRNA involved in the regulation of biosynthesis of secondary plant product is still poorly understood. In this chapter, we summarize the identification and characterization of miRNAs that participate in the regulation of the biosynthesis of secondary metabolites in plants and their use in the strategies to manipulate a controlled manipulation.

Carbon Fluxes between Primary Metabolism and Phenolic Pathway in Plant Tissues under Stress

International Journal of Molecular Sciences, 2015

Higher plants synthesize an amazing diversity of phenolic secondary metabolites. Phenolics are defined secondary metabolites or natural products because, originally, they were considered not essential for plant growth and development. Plant phenolics, like other natural compounds, provide the plant with specific adaptations to changing environmental conditions and, therefore, they are essential for plant defense mechanisms. Plant defensive traits are costly for plants due to the energy drain from growth toward defensive metabolite production. Being limited with environmental resources, plants have to decide how allocate these resources to various competing functions. This decision brings about trade-offs, i.e., promoting some functions by neglecting others as an inverse relationship. Many studies have been carried out in order to link an evaluation of plant performance (in terms of growth rate) with levels of defense-related metabolites. Available results suggest that environmental stresses and stress-induced phenolics could be linked by a transduction pathway that involves: (i) the proline redox cycle; (ii) the stimulated oxidative pentose phosphate pathway; and, in turn, (iii) the reduced growth of plant tissues.

Role and Regulation of Plants Phenolics in Abiotic Stress Tolerance: An Overview

2018

Plants are exposed to multifarious abiotic stresses in constantly changing environments that are unfavorable for growth and development (Zhu, 2016). These abiotic stresses include water (drought and flooding), heavy metals, salinity, excess or deficiency of nutrients, high and low temperatures (chilling and freezing), extreme levels of light (high and low), radiation (UV-B and UV-A; ultraviolet, UV), ozone, sulfur dioxide, mechanical factors, and other less frequently occurring stressors (Pereira, 2016). Plants being rooted in the environment they grow in have to adapt with the changing conditions due to abiotic stresses and the accumulation of phenolics in plant tissues are considered as an adaptive response of plants to these adverse environmental conditions (Pereira, 2016; Lattanzio, 2013).

Phenolic compounds in plant disease resistance

Phytoparasitica, 1988

We propose that an important first line in plant defense against infection is provided by the very rapid synthesis of phenolics and their polymerization in the cell wall. This rapid synthesis, which leaves no time for de novo enzyme synthesis, is regulated by the extreme pH-dependence of the hydroxylase, catalyzing the formation of caffeoyl-CoA from 4-coumaroyl-CoA. We further propose that elicitor treatment or infection causes rapid membrane changes leading to a decrease in cytoplasmic pH. This decrease would have the effect of activating the hydroxylase.

Role of phenolics in the resistance mechanisms of plants against fungal pathogens and insects

2006

Plant phenolics are secondary metabolites that encompass several classes structurally diverse of natural products biogenetically arising from the shikimate-phenylpropanoids-flavonoids pathways. Plants need phenolic compounds for pigmentation, growth, reproduction, resistance to pathogens and for many other functions. Therefore, they represent adaptive characters that have been subjected to natural

Role of Polyphenols in the Resistance Mechanisms of Plants Against Fungal Pathogens and Insects

Phytochemistry

Plant phenolics are secondary metabolites that encompass several classes structurally diverse of natural products biogenetically arising from the shikimate-phenylpropanoids-flavonoids pathways. Plants need phenolic compounds for pigmentation, growth, reproduction, resistance to pathogens and for many other functions. Therefore, they represent adaptive characters that have been subjected to natural Correspondence/Reprint request: Prof.