EDTA reduces cadmium toxicity in mustard (Brassica juncea L.) by enhancing metal chelation, antioxidant defense and glyoxalase systems

Abstract

To investigate the possible role of EDTA in mitigating cadmium (Cd) toxicity, we treated mustard (<em>Brassica juncea</em> L.) seedlings with CdCl<sub>2</sub> (0.5 mM and 1.0 mM, 3 days) alone and in combination with 0.5 mM EDTA in a semihydroponic medium. In the absence of EDTA, mustard seedlings accumulated Cd in their roots and shoots in a concentration dependent manner. Overaccumulation of Cd boosted generation of hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) and superoxide anions (O<sub>2</sub><sup>•−</sup>), increased lipoxygenase (LOX) activity, lipid peroxidation, and cytotoxic methylglyoxal (MG) content. It also disturbed components of the antioxidant defense and glyoxalase systems. Furthermore, Cd stress decreased growth, leaf relative water content (RWC) and chlorophyll (chl) content but augmented the proline (Pro) content. On the other hand, EDTA supplemented Cd-stressed seedlings improved the constituents of the AsA-GSH cycle with the upregulated activities of ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione peroxidase (GPX), superoxide dismutase (SOD), and catalase (CAT). Moreover, addition of EDTA to the Cd-stressed seedlings notably enhanced Gly I activity in contrast to the stress treatment. Ethylenediaminetetraacetic acid decreased Cd accumulation in the both shoots and roots, as well as increased other nonprotein thiols (NPTs) in leaves, including the phytochelatin (PC) content. It also decreased H<sub>2</sub>O<sub>2</sub> and O<sub>2</sub><sup>•−</sup> generation, lipid peroxidation and MG content but enhanced RWC, chl and Pro contents in the leaves, which confirmed the improved growth of seedlings. The findings of the study suggest that exogenous application of EDTA to the Cd-treated seedlings reduces Cd-induced oxidative injuries by restricting Cd uptake, increasing NPTs concentration and upregulating most of the components of their antioxidant defense and glyoxalase systems.

Biostimulants for the Regulation of Reactive Oxygen Species Metabolism in Plants under Abiotic Stress

“…The supplementation of EDTA increased the GSH levels by 11% in both levels (0.5 and 1.0 mM Cd) of stress and reduced the GSSG levels by 21% and 18% under 0.5 and 1.0 mM Cd stress, respectively, compared with Cd stress alone. Upregulation of antioxidant enzyme (APX, DHAR, MD-HAR, GR, SOD, CAT, and GPX) activities was also observed due to EDTA application [149]. Two levels of CA co-treatment on mustard plants exposed to two levels of Cd stress also showed almost similar results [148].…”

“…Organic acids like ethylenediaminetetraacetic acid (EDTA), γ-aminobutyric acid (GABA), maleic acid, citric acid, FA, and HA are gaining popularity among scientists and have been proven effective against HM stress. Mahmud et al [146][147][148][149] used Brassica juncea L. as the test crop and exposed it to Cd stress for 3 days. When exposed to 0.5 mM EDTA, 25.6, 26.1, and 27.6% reductions in thiobarbituric acid reactive substances (TBARS), H 2 O 2 content, and LOX activity, respectively, were observed in Cd (1.0 mM)-stressed seedlings compared with seedlings receiving only Cd treatment.…”

Regulation of Ascorbate-Glutathione Pathway in Mitigating Oxidative Damage in Plants under Abiotic Stress

“…The biosynthesis of PCs is accomplished by the enzyme PC synthase (PCS), which requires GSH as a substrate. The enzyme is crucial for metal detoxification, metal homeostasis, and stress tolerance [137].…”

Expression of Antioxidant Enzymes and Changes in Some Physiological Parameters Following the Short-term Heavy Metal Application in Wheat

“…[25]. In many studies, high concentrations of heavy metals are similarly said to cause decreases in seed germination, root and stem lengths and root-stem weights in plants [22,[26][27][28][29].…”