Antioxidant responses of peanut roots exposed to realistic groundwater doses of arsenate: Identification of glutathione S-transferase as a suitable biomarker for metalloid toxicity

Abstract

Arsenic (As)-polluted groundwater constitutes a serious problem for peanut plants, as roots can accumulate the metalloid in their edible parts. Characterization of stress responses to As may help to detect potential risks and identify mechanisms of tolerance, being the induction of oxidative stress a key feature. Fifteen-day old peanut plants were treated with arsenate in order to characterize the oxidative stress indexes and antioxidant response of the legume under realistic groundwater doses of the metalloid. Superoxide anion (O) and hydrogen peroxide (HO) histochemical staining along with the activities of NADPH oxidase, superoxide dismutase (SOD), catalase (CAT) and thiol (glutathione and thioredoxins) metabolism were determined in roots. Results showed that at 20 μM HAsO, peanut growth was reduced and the root architecture was altered. O and HO accumulated at the root epidermis, while lipid peroxidation, NADPH oxidase, SOD, CAT and glutathione S-transferase (GST) activities augmented. These variables increased with increasing As concentration (100 μM) while glutathione reductase (GR) and glutathione peroxidase/peroxiredoxin (GPX/PRX) were significantly decreased. These findings demonstrated that the metalloid induced physiological and biochemical alterations, being the NADPH oxidase enzyme implicated in the oxidative burst. Additionally, the strong induction of GST activity, even at the lowest HAsO doses studied, can be exploited as suitable biomarker of As toxicity in peanut plants, which may help to detect risks of As accumulation and select tolerant cultivars.

Targeting redox metabolism of the maize‐Azospirillum brasilense interaction exposed to arsenic‐affected groundwater

“…Different letters indicate significant differences between A. brasilense strains for the same As V dose. Different numbers indicate significant differences between As V doses for each inoculated strain (P < 0.05) according to a symbiotic interaction like soybean and peanut exposed to As or Cd (Bianucci et al, 2017(Bianucci et al, , 2018(Bianucci et al, , 2019Bianucci, Fabra, & Castro, 2012;Bianucci, Sobrino-Plata, et al, 2012). In this regard, previous work showed that maize inoculation with CD restrained arsenic translocation to aerial parts, limiting grain contamination when compared to Az39 (Peralta et al, 2019).…”

“…The root samples were ground in liquid nitrogen and the powder obtained was homogenized according to the enzyme evaluated. The supernatant from the homogenates for SOD (EC 1.15.1.1), CAT (EC 1.11.1.6), GPX/PRX (EC 1.11.1.9), GR (EC 1.6.4.2), and GST (EC 2.5.1.18) were obtained according to the methodology detailed by Bianucci et al (2017), and for MDHAR (EC 1.6.5.4) and DHAR (EC 1.8.5.1) as reported by Peco et al (2020). Protein concentration in plant extracts was determined according to Bradford (1976), using bovine serum albumin as standard.…”

“…In addition, the NADPH oxidase complex significantly contributes to this oxidative response (Mittler et al, 2011). Therefore, oxidative damage can occur on essential biomolecules like lipids, proteins and nucleic acids, leading to oxidative stress that is translated into a plethora of morphological, physiological, biochemical, and molecular alterations (Begum et al, 2016; Bianucci et al, 2017, 2018, 2019, 2020; Peralta et al, 2019, 2020; Shahid et al, 2017; Singh et al, 2017, b).…”

Protein and transcript profiling analysis of the response of Yarrowia lipolytica Y‐2 in the degradation of ochratoxin A

“…Glutathione S‐transferase belongs to the family of phase II detoxification enzymes with a predominant peroxidase activity (Townsend & Tew, ; Vontas, Small, & Hemingway, ). This enzyme depleted glutathione directly to detoxify organic peroxides, radicals and xenobiotics and thus regulating cells tolerance and promoting oxidising conditions (Anjum et al, ; Bianucci et al, ; Schröder, Lyubenova, & Huber, ). It was reported that cytochrome P450 monooxygenase, glutathione S‐transferase, and AKR, were all pivotal in detoxification of aflatoxin B (Hayes, Judah, & Neal, ; Knight, Primiano, Groopman, Kensler, & Sutter, ).…”

Role of glutathione in tolerance to arsenite in Salvinia molesta, an aquatic fern

“…GSTs are enzymes that are capable of catalyzing xenobiotic complexation with GSH, making the pollutant less reactive in the intracellular environment. High GST activity can be considered to be a biomarker of As tolerance in plants (Bianucci et al 2017). Although submerged leaves have experienced increases in GST activity, the arsenic amount in their tissues may have generated a stress that exceeded their tolerance ability.…”