Ecotype-Specific Pathways of Reactive Oxygen Species Deactivation in Facultative Metallophyte Silene vulgaris (Moench) Garcke Treated with Heavy Metals

Abstract

This research aimed to indicate mechanisms involved in protection against the imbalanced generation of reactive oxygen species (ROS) during heavy metals (HMs) exposition of Silene vulgaris ecotypes with different levels of metal tolerance. Specimens of non-metallicolous (NM), calamine (CAL), and serpentine (SER) ecotypes were treated in vitro with Zn, Pb, and Cd ions applied simultaneously in concentrations that reflected their contents in natural habitats of the CAL ecotype (1× HMs) and 2.5- or 5.0-times higher than the first one. Our findings confirmed the sensitivity of the NM ecotype and revealed that the SER ecotype was not fully adapted to the HM mixture, since intensified lipid peroxidation, ultrastructural alternations, and decline in photosynthetic pigments’ content were ascertained under HM treatment. These changes resulted from insufficient antioxidant defense mechanisms based only on ascorbate peroxidase (APX) activity assisted (depending on HMs concentration) by glutathione-S-transferase (GST) and peroxidase activity at pH 6.8 in the NM ecotype or by GST and guaiacol-type peroxidase in the SER one. In turn, CAL specimens showed a hormetic reaction to 1× HMs, which manifested by both increased accumulation of pigments and most non-enzymatic antioxidants and enhanced activity of catalase and enzymes from the peroxidase family (with the exception of APX). Interestingly, no changes in superoxide dismutase activity were noticed in metallicolous ecotypes. To sum up, the ROS scavenging pathways in S. vulgaris relied on antioxidants specific to the respective ecotypes, however the synthesis of polyphenols was proved to be a universal reaction to HMs.

Reactive oxygen species metabolism and photosynthetic performance in leaves of Hordeum vulgare plants co-infested with Heterodera filipjevi and Aceria tosichella

“…The enzymatic machinery consists of superoxide dismutase (SOD), catalase (CAT), multifarious peroxidases and enzymes of the Foyer–Halliwell–Asada cycle (Labudda and Azam 2014 ; Muszyńska et al 2018 ; Kapoor et al 2019 ). The non‐enzymatic mechanisms are mainly based on the reduced glutathione (GSH) and ascorbate (ASA) and an abundant group of the phenol metabolites (Saxena et al 2016 ; Durak et al 2019 ; Muszyńska et al 2020 ). Among the phenols, salicylic acid (SA) is a phytohormonal molecule, which modulates many plant reactions to the environmental stresses (Morkunas et al 2011 , 2018 ; Maruri-López et al 2019 ; Formela-Luboińska et al 2020 ).…”

Functional Trait-Based Screening of Zn-Pb Tolerant Wild Plant Species at an Abandoned Mine Site in Gard (France) for Rehabilitation of Mediterranean Metal-Contaminated Soils

“…N. caerulescens is sometimes considered as a Zn-hyperaccumulator and Pb co-accumulator [ 34 ]. A previous work on N. caerulescens also shows a negative correlation between Zn content in shoot parts and Ca and Mg concentrations in shoot parts due to competition between these different cations [ 13 ]. Synergistic and antagonistic interactions for element absorption in plants is a challenging field of research and there is still a need for more knowledge.…”

“…Moreover, plant ecotypes in the mining sites are tolerant to mixed toxic metals in the soil solution and not only of a single metal such as Zn. For example, it has been recently demonstrated that Silene vulgaris ecotypes from calamine soils were fully adapted to heavy metal mixture (Zn, Pb and Cd) compared to ecotypes from both serpentine and non-metallicolous soils [ 13 ]. These adaptations depend on their capacity for reactive oxygen species scavenging and TMM compartmentalization in plant parts to avoid their toxicity [ 2 , 6 ].…”

Photosynthetic apparatus efficiency, phenolic acid profiling and pattern of chosen phytohormones in pseudometallophyte Alyssum montanum

“…Heavy metals (HMs) are one of the main abiotic stress factors that lead to multiple alterations in plant physiology and biochemistry, including water uptake, nutrient distribution, transpiration or nitrogen metabolism 1 – 3 . After exceeding the optimum threshold, accumulated HMs may also affect photosynthesis in many ways.…”