Metabolic Pathway of Natural Antioxidants, Antioxidant Enzymes and ROS Providence

Abstract

Based on the origin, we can classify different types of stress. Environmental factors, such as high light intensity, adverse temperature, drought, or soil salinity, are summarized as abiotic stresses and discriminated from biotic stresses that are exerted by pathogens and herbivores, for instance. It was an unexpected observation that overproduction of reactive oxygen species (ROS) is a common response to all kinds of stress investigated so far. With respect to applied aspects in agriculture and crop breeding, this observation allows using ROS production as a measure to rank the stress perception of individual plants. ROS are important messengers in cell signaling, but exceeding a concentration threshold causes damage. This requires fine-tuning of ROS production and degradation rates. In general, there are two options to control cellular ROS levels, (I) ROS scavenging at the expense of antioxidant consumption and (II) enzyme-controlled degradation of ROS. As antioxidants are limited in quantity, the first strategy only allows temporarily buffering of a certain cellular ROS level. This way, it prevents spells of eventually damaging ROS concentrations. In this review, we focus on the second strategy. We discuss how enzyme-controlled degradation of ROS integrates into plant metabolism. Enzyme activities can be continuously operative. Cellular homeostasis can be achieved by regulation of respective gene expression and subsequent regulation of the enzyme activities. A better understanding of this interplay allows for identifying traits for stress tolerance breeding of crops. As a side effect, the result also may be used to identify cultivation methods modifying crop metabolism, thus resulting in special crop quality.

ZmNAC074, a maize stress-responsive NAC transcription factor, confers heat stress tolerance in transgenic Arabidopsis

“…ROS is similar to a double-edged sword and ROS homeostasis is vital for plant growth, development and acclimatization against stresses ( Sachdev et al., 2021 ). Excessive ROS generated by heat stress are toxic molecules capable of causing oxidative damage to proteins, nucleic acids, carbohydrates, cell membranes, lipids, and other sites of cells ( Huchzermeyer et al., 2022 ). However, plants have evolved an antioxidant defense system including diverse antioxidants like SOD and CAT, which can protect them against oxidative damage ( Baxter et al., 2014 ).…”

Influence of Drought Stress on Physiological Responses and Bioactive Compounds in Chicory (Cichorium intybus L.): Opportunity for a Sustainable Agriculture

“…Plants may develop different morpho-physiological and adaptation mechanisms in response to environmental stresses [ 16 ]. An increase in the antioxidant systems, such as enzymes and secondary metabolites (ascorbic acid, glutathione, tocols, carotenoids, flavones, and flavonoids) has been observed to enhance drought tolerance [ 17 , 18 , 19 ], even if this behavior was found to depend on phenological stage, genotype, organs of the plants (fruits and leaves), severity and length of the stress [ 20 , 21 ]. In some studies on fruits and vegetables under water stress conditions, an increment of β-carotene and carotenoids was found [ 22 , 23 , 24 ], while, in other studies, a reduced tissue concentration of carotenoids was observed [ 25 , 26 ].…”

Damage-associated molecular patterns in vitiligo: igniter fuse from oxidative stress to melanocyte loss

“…Mediated by disturbed redox homeostasis, oxidative stress is characterized by imbalanced pro-oxidant and antioxidant levels [ 8 ], and may be considered a crucial initiator of vitiligo [ 9 ]. Reactive oxygen species (ROS) generation is an instant intracellular response when cells are exposed to an external environment [ 10 ]. There are three major ROS: superoxide anion, hydrogen peroxide, and hydroxyl radical.…”