Heavy Metal-Induced Differential Responses to Oxidative Stress and Protection by Mycorrhization in Sunflowers Grown in Lab and Field Scales

Abstract

Heavy metals (HM) are some of the most frequent soil contaminants and a cause for long-term loss of soils, for destruction of natural habitats, loss of agricultural and inhabitable soils, and numerous health problems for wildlife and the human population. Reactive oxygen species (ROS) are generated during the normal metabolism of plants and activated by both biotic and abiotic stressors such as HM [1]. They are key messengers in plant responses to HM stress as part of their defense and adaptation mechanisms, either directly, by disturbing electron transport, or indirectly, by disturbing metabolic reactions, inactivation, and down-regulation of stress response enzymes and depletion of antioxidant substrates [2,3]. They also affect the photosynthetic system at many levels, leading to Pol. J. Environ. Stud. Vol. 24, No. 3 (2015), [1235][1236][1237][1238][1239][1240][1241][1242][1243][1244][1245][1246][1247] AbstractThe influence of arbuscular mycorrhizal (AM) fungi (Glomus intraradices) and of heavy metal stress on the characteristics of biomass production, as well as non-enzymatic and enzymatic variables in the roots, shoots, and leaves of sunflower (Helianthus annuus L.) plants were studied at pot and field scales. The intensity of the mycorrhizal colonization (M%) and the arbuscular abundance in the root system (A%) were found to be higher in the sunflower grown at lab scale (artificially inoculated) than that grown at field scale (natively inoculated). Thus, the AM symbiosis with the sunflower root system exposed to a different degree of pollution had a differential protective effect on plants at lab and field scales. A huge biomass of sunflower was harvested from the field compared to that obtained from the lab experiment. Furthermore, after measuring the biochemical variables of the plant parts, the results indicated a decrease in field for the superoxide dismutase and peroxidase activity, for the lipid peroxidation content, and for the assimilating pigments, while all quantified variables showed almost the same pattern of variation in all three plant parts. Consequently, it can be concluded that it is possible to use biochemical response variables, which in the case of our study are consistent with the protective effect of the fungus, as environmental biomarkers for soils with moderate pollution.

Controlling Nitrate and Heavy Metals Content in Leeks (Allium porrum L.) Using Arbuscular Mycorrhizal Fungi Inoculation

“…An important role in inoculation with arbuscular mycorrhizal fungi is also played by the question of the accumulation of harmful substances, such as heavy metals or nitrates. Paun et al [21] investigated how AM fungi protect plants from toxic elements (HMs) by retaining them in their root systems, and they also have the potential to change and modify the rhizosphere environment [21]. Nitrates are not in themselves harmful until they are reduced into nitrites by bacteria living in the human digestive tract.…”

Accumulation of Heavy Metal Ions by Eichhornia Crassipes from Battery Industry Effluent under the Influence of Cattle Manure

“…TrF has a direct effect of metal ions in the contaminated medium and the metal ions accumulated by the plant. It is due to competitive nature of heavy metal ions ready to enter into plants system [27][28][29]. As most of the metal ions are already accumulated by the plant and the TrF value only increases for a specific period.…”

Signals and Machinery for Mycorrhizae and Cereal and Oilseed Interactions towards Improved Tolerance to Environmental Stresses

“…However, AMF have been shown to detoxify HMs contamination in oilseeds by improving nutrient uptake, physiological traits, and antioxidant machinery, and by decreasing MDA content and root-to-shoot HMs translocation. These mechanisms have been demonstrated in sunflower [ 109 ] and soybean [ 110 , 111 ]. For instance, R. intraradices -inoculated soybean grown under Cu, Pb, and Zn showed improved P acquisition and grain yield [ 111 ].…”

“…Furthermore, AMF bind HMs through intra- and extra-radical mycelium at the root cortex, and mycorrhizal structures store HMs in the mycelium, acting as a barrier-like strategy that prevents metal translocation to oilseed shoots and seeds. Păun et al [ 109 ] observed that the sunflower plants inoculated with R. intraradices and grown under contaminated soils had lower As, Cr, and Ni contents and improved P content compared to control non-mycorrhizal plants. It is suggested that AMF extra- and intra-radical mycelium aid in binding, adsorbing, complexing, precipitating, and crystallizing HMs against AMF hyphal walls.…”