Foliar-Applied Glutathione Mitigates Cadmium-Induced Oxidative Stress by Modulating Antioxidant-Scavenging, Redox-Regulating, and Hormone-Balancing Systems in Brassica napus

Abstract

The antioxidant glutathione (GSH) mitigates adverse physio-metabolic effects and defends against abiotic types of stress, such as cadmium (Cd) stress. However, its function and role in resisting Cd phytotoxicity by leveraging plant antioxidant-scavenging, redox-regulating, and hormone-balancing systems have not been comprehensively and systematically demonstrated in the Cd-hyperaccumulating plant Brassica napus L. cv. Tammi (oilseed rape). In this study, the effects of exogenously applied GSH to the leaves of B. napus seedlings exposed to Cd (10 μM) were investigated. As a result, Cd stress alone significantly inhibited growth and increased the levels of reactive oxygen species (ROS) and the bioaccumulation of Cd in the seedlings compared with those in unstressed controls. Furthermore, Cd stress induced an imbalance in plant stress hormone levels and decreases in endogenous GSH levels and GSH redox ratios, which were correlated with reductions in ascorbate (AsA) and/or nicotinamide adenine dinucleotide phosphate (NADPH) redox states. However, the exogenous application of GSH to Cd-stressed B. napus seedlings reduced Cd-induced ROS levels and enhanced antioxidant-scavenging defenses and redox regulation by both increasing seedling AsA, GSH, and NADPH concentrations and rebalancing stress hormones, thereby enhancing Cd uptake and accumulation. These results demonstrate that GSH improved plant redox status by upregulating the AsA-GSH-NADPH cycle and reestablishing normal hormonal balance. This indicates that exogenously applied GSH can mitigate Cd phytotoxicity in B. napus and possibly other plants. Therefore, GSH can potentially be applied to Cd-polluted soil for plant remediation.

Glutathione Promotes Degradation and Metabolism of Residual Fungicides by Inducing UDP-Glycosyltransferase Genes in Tomato

“…Similarly, GSSG treatment could also increase the accumulation of chlorothalonil, although there was no significant difference in NPT content between GSSG treatment and pesticide treatment alone. Jung et al (2021) also found that foliar application of glutathione could reduce cadmium-induced oxidative stress.…”

Lead exposure dose-dependently affects oxidative stress, AsA-GSH, photosynthesis, and mineral content in pakchoi (Brassica chinensis L.)

“…The effect of Pb stress on the chlorophyll content and chloroplast formation of pakchoi. oxidative stress and imbalance of the AsA-GSH cycle (Zhou et al, 2018;Jung et al, 2021). Salt-alkali mixed stress reduces the key enzymes of the AsA synthesis pathway, as well as L-galactose dehydrogenase (GDH) and L-galactose-1,4-lactone dehydrogenase (GLDH) activities, and weakens AsA-GSH cycle efficiency, thereby causing oxidative damage to naked oats (Liu et al, 2021).…”

“…The AsA-GSH system is composed of AsA (that is, vitamin C)-DHA and GSH-GSSG processes, as well as enzymes involved in these two processes, and resists environmental stresses such as low light levels ( Hu et al., 2019 ). According to reports, Cd and Cu can accumulate in plants, thereby causing the activities of MDHAR, APX and DHAR to decrease, abnormal levels of AsA and DHA, and a decreased GSH and GSSG content, leading to oxidative stress and imbalance of the AsA-GSH cycle ( Zhou et al., 2018 ; Jung et al., 2021 ). Salt-alkali mixed stress reduces the key enzymes of the AsA synthesis pathway, as well as L-galactose dehydrogenase (GDH) and L-galactose-1,4-lactone dehydrogenase (GLDH) activities, and weakens AsA-GSH cycle efficiency, thereby causing oxidative damage to naked oats ( Liu et al., 2021 ).…”

Growth, Yield, and Antioxidant Traits of Different Parts of Beetroot as Affected by Vermicompost and Glutathione

“…Moreover; it utilized in sulphur metabolism, metabolism regulation, cell protection, redox signaling, and regulation of gene expression (12). Semida et al (26) noticed that spraying glutathione mitigated salinity harmful effect and increased enzymatic and non-enzymatic antioxidants compared to control in Vicia faba L. Jung et al (15) observed significant increase in scavenging activity and significant reduction of cadmium levels when applying exogenous glutathione on Brassica napus plant. Thus, this study was aimed to the impact of vermicompost and glutathione on pigments accumulation and antioxidant potency in beetroot plant.…”