Eriophorum angustifolium and Lolium perenne metabolic adaptations to metals- and metalloids-induced anomalies in the vicinity of a chemical industrial complex

Abstract

As plants constitute the foundation of the food chain, concerns have been raised about the possibility of toxic concentrations of metals and metalloids being transported from plants to the higher food chain strata. In this perspective, the use of important phytotoxicity endpoints may be of utmost significance in assessing the hazardous nature of metals and metalloids and also in developing ecological soil screening levels. The current study aimed to investigate the role of glutathione (GSH) and its associated enzymes in the metabolic adaptation of two grass species namely Eriophorum angustifolium Honck. and Lolium perenne L. to metals and metalloids stress in the vicinity of a chemical industrial complex (Estarreja, Portugal). Soil and plant samples were collected from contaminated (C) and non-contaminated (reference, R) sites, respectively, near and away from the Estarreja Chemical Complex, Portugal. Soils (from 0 to 10 and 10 to 20 cm depths) were analyzed for pH, organic carbon, and metals and metalloids concentrations. Plant samples were processed fresh for physiological and biochemical estimations, while oven-dried plant samples were used for metals and metalloids determinations following standard methodologies. Both soils and plants from the industrial area exhibited differential concentrations of major metals and metalloids including As, Cu, Hg, Pb, and Zn. In particular, L. perenne shoot displayed significantly higher and lower concentrations of Pb and As, respectively at contaminated site (vs. E. angustifolium). Irrespective of sites, L. perenne shoot exhibited significantly higher total GSH pool, oxidized glutathione (GSSG) and oxidized protein (vs. E. angustifolium). Additionally, severe damages to photosynthetic pigments, proteins, cellular membrane integrity (in terms of electrolyte leakage), and lipid peroxidation were also perceptible in L. perenne shoot. Contrarily, irrespective of the sites, activities of catalase and GSH-regenerating enzyme, GSH reductase, and GSH-metabolizing enzymes such as GSH peroxidase and GSH sulfotransferase were significantly higher in shoot of E. angustifolium. Despite the higher total GSH content, L. perenne is vulnerable to multi-metals-induced stress in comparison to E. angustifolium as depicted by increased GSH- and protein oxidation, low reactive oxygen radical-processing potential (exhibited in terms of low catalase activity) and poor GSH pool utilization efficiency (in terms of lower GSH-associated enzymes activities). The outcome of the present study may be significant for understanding vital GSH-mediated metals and metalloids tolerance mechanisms in plants as well as their unsuitability for animal consumption due to higher metals and metalloids burdens.

Lipids and proteins—major targets of oxidative modifications in abiotic stressed plants

“…Abiotic stress, reactive oxygen species, and biomolecules Abiotic stresses (such as drought, salinity, radiations, extreme temperatures including freezing/low and high temperatures, and chemicals such as metals/metalloids) continue to have a significant impact on plant growth and development, limiting the global crop production significantly (reviewed by Mahajan and Tuteja 2005;Gill and Tuteja 2010;Cramer et al 2011;Anjum et al 2012Anjum et al , 2014aKrasensky and Jonak 2012). Normal aerobic metabolism in plants results in the generation of reactive oxygen species (ROS; such as O 2…”

Managing the pools of cellular redox buffers and the control of oxidative stress during the ontogeny of drought-exposed mungbean (Vigna radiata L.)—role of sulfur nutrition

“…Cellular membrane integrity in leaves was assayed by measuring the EL according to Anjum et al (2013). In brief, fresh leaves (1.0 g) were kept in glass vials containing 10 ml deionized water.…”

“…EL was expressed following the formula EL = EC1/EC2 × 100. Membrane lipid peroxidation was estimated in terms of thiobarbituric acid reactive substances (TBARS) contents adopting the method of Dhindsa et al (1981) as described by Anjum et al (2013). Briefly, fresh leaves (1.0 g) were ground in liquid nitrogen, mixed with 0.73% 2-thiobarbituric acid in 12% trichloroacetic acid, incubated for 30 min in boiling water, ice-cooled, centrifuged at 1000×g for 10 min at 4 • C and the absorbance measured in the supernatant at 532 nm.…”

“…Both AsA and GSH (tripeptide GSH; γ-glutamate-cysteine-glycine) are cellular redox buffers closely linked in major physiological functions. Nevertheless, in conjunction with other components of AsA-GSH pathway, both AsA and GSH together determine the lifetime of varied ROS and their reaction products within the cellular environment and provide crucial protection against oxidative damage (Anjum et al, 2010(Anjum et al, , 2012a(Anjum et al, , 2013. In recent studies, exogenous application of AsA or GSH was reported to help plants to withstand consequences caused by a range of abiotic stresses including Cd (Cai et al, 2011;Son et al, 2014), salinity (Wang et al, 2014) and high temperature (Nahar et al, 2015).…”

“…The cumulative role of mineral nutrients in modulating cellular levels of AsA and GSH, and in strengthening the plant antioxidant defense system has been discussed extensively (Anjum et al, 2010(Anjum et al, , 2012a(Anjum et al, , 2013Gill et al, 2011). Sulfur (S) is the fourth essential macronutrient for plants, after N, P and K, and plays a vital role in the regulation of plant growth, development and productivity (Hawkesford, 2000), via affecting leaf chlorophyll, N content and photosynthetic enzymes.…”