Accumulation of Flavonols over Hydroxycinnamic Acids Favors Oxidative Damage Protection under Abiotic Stress

Abstract

Efficient detoxification of reactive oxygen species (ROS) is thought to play a key role in enhancing the tolerance of plants to abiotic stresses. Although multiple pathways, enzymes, and antioxidants are present in plants, their exact roles during different stress responses remain unclear. Here, we report on the characterization of the different antioxidant mechanisms of tomato plants subjected to heat stress, salinity stress, or a combination of both stresses. All the treatments applied induced an increase of oxidative stress, with the salinity treatment being the most aggressive, resulting in plants with the lowest biomass, and the highest levels of H2O2 accumulation, lipid peroxidation, and protein oxidation. However, the results obtained from the transcript expression study and enzymatic activities related to the ascorbate-glutathione pathway did not fully explain the differences in the oxidative damage observed between salinity and the combination of salinity and heat. An exhaustive metabolomics study revealed the differential accumulation of phenolic compounds depending on the type of abiotic stress applied. An analysis at gene and enzyme levels of the phenylpropanoid metabolism concluded that under conditions where flavonols accumulated to a greater degree as compared to hydroxycinnamic acids, the oxidative damage was lower, highlighting the importance of flavonols as powerful antioxidants, and their role in abiotic stress tolerance.

Reactive oxygen species, abiotic stress and stress combination

“…From the standpoint of ROS involvement, a number of studies have shown that ROS levels, the expression of different ROS‐scavenging enzymes and the level of different antioxidants display a unique pattern during stress combination that is different than that found to be induced by each of the different stresses applied separately. These changes were reflected in levels of O 2 .‐ , H 2 O 2 , byproducts of lipid peroxidation, expression of enzymes such as SOD, APX, CAT, AOX, peroxidases, glutathione‐S‐transferase, glutathione reductase and GPX, accumulation of antioxidants such as ascorbate, GSH, flavonols, phenolic compounds, alkaloids, tocopherol and carotenoids, and accumulation of osmoprotectants such as proline, glycine betaine, trehalose and sucrose (Keleş and Öncel, ; Rizhsky et al ., ; Rizhsky et al ., ; Giraud et al ., ; Vile et al ., ; Prasch and Sonnewald, ; Rasmussen et al ., ; Li et al ., ; Rivero et al ., ; Suzuki et al ., ; Vuleta et al ., ; Jin et al ., ; Pandey et al ., ; Carvalho et al ., ; Martinez et al ., ). Because the combination of two different stresses imposes on plants a unique set of physiological restrains, it is likely that the ROS signature generated under conditions of stress combination is unique (Figure ).…”

A class B heat shock factor selected for during soybean domestication contributes to salt tolerance by promoting flavonoid biosynthesis

“…Previous studies have shown that flavonoids are powerful antioxidants involved in abiotic stress responses (Nakabayashi et al, 2014;Martinez et al, 2016). Flavonols inhibit the ABA-dependent ROS burst to regulate stomatal movement (Watkins et al, 2017).…”

Reduced nitrogen supply enhances the cellular antioxidant potential of phenolic extracts through alteration of the phenolic composition in lettuce (Lactuca sativa L.)

“…This is probably explained by the fact that 2–3 days of LN treatment, as was the case in the present study, is adequate to stimulate the synthesis of phenolic compounds in lettuce. This increased production of phenolic compounds probably occurs via a mechanism that enables plants to resist the oxidative stress resulting from nitrogen deficiency …”

“…This increased production of phenolic compounds probably occurs via a mechanism that enables plants to resist the oxidative stress resulting from nitrogen deficiency. 31,32 Phenolic compounds have also been proved to counteract the harmful effects of excess ROS in the human body, which is closely linked to oxidative stress and eventually causes persistent or reversible cellular damage. 3,33 In the present study, the viability of Caco-2 cells decreased in a dose-dependent manner after treatment with H 2 O 2 for 6 h (Fig.…”