Selenium Toxicity in Plants and Environment: Biogeochemistry and Remediation Possibilities

Abstract

Selenium (Se) is a widely distributed trace element with dual (beneficial or toxic) effects for humans, animals, and plants. The availability of Se in the soil is reliant on the structure of the parental material and the procedures succeeding to soil formation. Anthropogenic activities affect the content of Se in the environment. Although plants are the core source of Se in animal and human diet, the role of Se in plants is still debatable. A low concentration of Se can be beneficial for plant growth, development, and ecophysiology both under optimum and unfavorable environmental conditions. However, excess Se results in toxic effects, especially in Se sensitive plants, due to changing structure and function of proteins and induce oxidative/nitrosative stress, which disrupts several metabolic processes. Contrary, Se hyperaccumulators absorb and tolerate exceedingly large amounts of Se, could be potentially used to remediate, i.e., remove, transfer, stabilize, and/or detoxify Se-contaminants in the soil and groundwater. Thereby, Se-hyperaccumulators can play a dynamic role in overcoming global problem Se-inadequacy and toxicity. However, the knowledge of Se uptake and metabolism is essential for the effective phytoremediation to remove this element. Moreover, selecting the most efficient species accumulating Se is crucial for successful phytoremediation of a particular Se-contaminated area. This review emphasizes Se toxicity in plants and the environment with regards to Se biogeochemistry and phytoremediation aspects. This review follows a critical approach and stimulates thought for future research avenues.

The Defensive Role of Endogenous H2S in Brassica rapa against Mercury-Selenium Combined Stress

“…Hg 2+ has strong affinity to -SH groups in functional proteins [ 41 ]. Cys in proteins can be easily replaced by SeCys [ 8 ]. Both actions are detrimental to the proteins.…”

“…However, Se application with excess concentration shows synergistic toxic effect with Hg [ 7 ]. Excessive Se is an emerging environmental problem [ 8 ]. Se and Hg frequently coexist in the environment [ 9 ].…”

Ethylene Suppresses Abscisic Acid, Modulates Antioxidant System to Counteract Arsenic-Inhibited Photosynthetic Performance in the Presence of Selenium in Mustard

“…Selenium (Se) is well-known as a beneficial element, functioning in the control of growth and development under normal and stressful conditions at lower concentration (Khan et al, 2015 ; Hasanuzzaman et al, 2022 ). Selenium enhances the metals/metalloids toxicity tolerance in plants (Hasanuzzaman et al, 2020a , b , 2022 ; Zhang et al, 2020 ). It has been shown to detoxify ROS through upregulating the activity of antioxidant enzymes (Hasanuzzaman and Fujita, 2011 ; Srivastava et al, 2016 ; Hasanuzzaman et al, 2020a , b ), leading to the protection of photosynthetic and growth capabilities (Khan et al, 2015 ).…”

“…Selenium enhances the metals/metalloids toxicity tolerance in plants (Hasanuzzaman et al, 2020a , b , 2022 ; Zhang et al, 2020 ). It has been shown to detoxify ROS through upregulating the activity of antioxidant enzymes (Hasanuzzaman and Fujita, 2011 ; Srivastava et al, 2016 ; Hasanuzzaman et al, 2020a , b ), leading to the protection of photosynthetic and growth capabilities (Khan et al, 2015 ). Supplying exogenous Se to Brassica napus improves enzymatic and non-enzymatic antioxidant processes and increases GSH content, enhancing plant immunity to Cd-induced oxidative harm (Hasanuzzaman et al, 2012 ).…”

In Vitro Evaluation of the Inhibitory Activity of Different Selenium Chemical Forms on the Growth of a Fusarium proliferatum Strain Isolated from Rice Seedlings

“…In addition to humans and animals, Se is also beneficial to plants when applied at low concentrations [5][6][7][8]. For example, Se contributes to the control of water status [9], prevents oxidative stress, delays senescence, and promotes growth [10].…”