ROS Homeostasis Involved in Dose-Dependent Responses of Arabidopsis Seedlings to Copper Toxicity

Abstract

As an essential element in plant nutrition, copper (Cu) can promote or inhibit plant growth depending on its concentration. However, the dose-dependent effects of copper, particularly on DNA damage associated with reactive oxygen species (ROS) homeostasis, are much less understood. In this work, we analyzed the dual effect of Cu (5, 20, and 60 μM) on the reproductive performance of Arabidopsis plants. Whereas Cu5 promoted inflorescence initiation and increased kilo seed weight, two higher concentrations, Cu20 and Cu60, delayed inflorescence initiation and negatively affected silique size. Excess Cu also induced changes in cellular redox homeostasis, which was examined by in situ visualization and measurements of ROS, including superoxide (O2•−), hydrogen peroxide (H2O2), malonyldialdehyde (MDA), and plasma membrane damage. The most dramatic increases in the production of O2•− and H2O2 along with increased activity of superoxide dismutase (SOD) and glutathione peroxidase (GPX) and decreased activity of catalase (CAT) and ascorbate peroxidase (APX) were observed in roots with Cu60. Oxidative stress also modulated the expression levels of a number of genes involved in the DNA damage response (DDR), particularly those related to DNA repair. The Cu-induced chlorosis of Arabidopsis seedlings could be alleviated by exogenous addition of glutathione (GSH) and ascorbate (Asc), as the chlorophyll content was significantly increased. Overall, internal homeostasis ROS and the associated DDR pathway and the corresponding scavenging mechanisms play a central role in the response of Arabidopsis to oxidative stress induced by inhibitory Cu concentrations. Our results have shown, for the first time, that the biphasic responses of Arabidopsis seedlings to increasing Cu concentrations involve different DNA damage responses and oxidative reactions. They provide the basis for elucidating the network of Cu-induced DDR-related genes and the regulatory mechanism of the complex ROS production and scavenging system.

Assessing the Impacts of Cu and Mo Engineered Nanomaterials on Crop Plant Growth Using a Targeted Proteomics Approach

“…This result correlated well with the high copper concentrations in leaves exposed via this route, which can lead to oxidative stress in plant cells due to the generation of reactive oxygen species (ROS). 43 The mostly downregulated proteins (root exposure: 0.35 < FC < 0.74; leaf exposure: 0.49 < FC < 0.72) observed in response to Cu exposure in leaves suggests that the plant initiated specific responses to mitigate the effects of copper-induced oxidative stress. This includes regulating the expression of enzymes like catalase (P21), a vital enzyme in the cellular defense against oxidative stress by efficiently breaking down hydrogen peroxide, to help protect cells from the damaging effects of ROS, contributing to overall cellular health and function.…”

“…However, 18 proteins (involved in 11 pathways) showed significant changes particularly in leaf tissues and when exposure was via leaves (Figure ), which indicates that Cu has a more localized impact particularly. This result correlated well with the high copper concentrations in leaves exposed via this route, which can lead to oxidative stress in plant cells due to the generation of reactive oxygen species (ROS) . The mostly downregulated proteins (root exposure: 0.35 < FC < 0.74; leaf exposure: 0.49 < FC < 0.72) observed in response to Cu exposure in leaves suggests that the plant initiated specific responses to mitigate the effects of copper-induced oxidative stress.…”

Decrypting Molecular Mechanisms Involved in Counteracting Copper and Nickel Toxicity in Jack Pine (Pinus banksiana) Based on Transcriptomic Analysis

“…Excess nickel has also been shown to elicit DNA damage and reduce DNA content, although the specific mechanisms are not well documented in plants [88,89]. The high proportion of genes associated with nuclease activity indicates different levels of DNA repair mechanisms, which may be used to mitigate the oxidative stress on DNA induced by heavy metals [90]. It implies a possible function related to DNA methylation and the epigenetic modulation of gene expression.…”