Soil Sulfur Sources Differentially Enhance Cadmium Tolerance in Indian Mustard (Brassica juncea L.)

Abstract

The effect of four soil-applied sulfur (100 mg S kg−1 soil (100S) and 200 mg S kg−1 soil (200S)) in different sources (elemental S, ammonium sulfate, gypsum or magnesium sulfate) in protecting mustard (Brassica juncea L. (Czern & Coss.)) from cadmium effects was studied. Based on the observed reduction in growth and photosynthesis in plants subjected to 100 and 200 mg Cd kg−1 soil, B. juncea cv. Giriraj was selected as the most Cd-tolerant among five cultivars (namely, Giriraj, RH-0749, Pusa Agrani, RH-406, and Pusa Tarak). Sulfur applied to soil mitigated the negative impact of Cd on sulfur assimilation, cell viability, and photosynthetic functions, with a lower lipid peroxidation, electrolyte leakage, and contents of reactive oxygen species (ROS: hydrogen peroxide, H2O2, and superoxide anion, O2•−). Generally, added S caused higher activity of antioxidant enzymes (ascorbate peroxidase, catalase and superoxide dismutase), contents of ascorbate (AsA) and reduced glutathione (GSH); increases in the activities of their regenerating enzymes (dehydroascorbate reductase and glutathione reductase); as well as rises in S assimilation, biosynthesis of non-protein thiols (NPTs), and phytochelatins (PCs). Compared to the other S-sources tested, elemental S more prominently protected B. juncea cv. Giriraj against Cd-impacts by minimizing Cd-accumulation and its root-to-shoot translocation; decreasing cellular ROS and membrane damage, and improving Cd-chelation (NPTs and PCs), so strengthening the defense machinery against Cd. The results suggest the use of elemental S for favoring the growth and development of cultivated plants also in Cd-contaminated agricultural soils.

Exogenously-Sourced Salicylic Acid Imparts Resilience towards Arsenic Stress by Modulating Photosynthesis, Antioxidant Potential and Arsenic Sequestration in Brassica napus Plants

“…Additionally, GSH is the most abundant soluble antioxidant inside cells, which launches the antioxidant defense system so that they can adjust to environmental challenges and stresses [ 12 , 82 ]. Accordingly, GSH can efficaciously scavenge ROS and participate in the formation of phytochelatins (PCs), which bring about the vacuolar sequestration of metals/metalloids in plants [ 11 , 82 ]. The antioxidant GSH also helps in the protection of cell membranes from peroxidation [ 11 , 82 ].…”

“…Accordingly, GSH can efficaciously scavenge ROS and participate in the formation of phytochelatins (PCs), which bring about the vacuolar sequestration of metals/metalloids in plants [ 11 , 82 ]. The antioxidant GSH also helps in the protection of cell membranes from peroxidation [ 11 , 82 ]. Thus, the 500 mM SA application perceptibly participates in the reduction of oxidative stress by involving antioxidants that result in the protection of B. napus plants under As stress.…”

“…Once inside the plants, As instigates the robust production of reactive oxygen species (ROS) that results in the membrane lipid peroxidation and thus disrupts redox homeostasis of the cell [ 8 , 10 ]. The common ROS produced in plant cells comprises hydrogen peroxide (H 2 O 2 ), hydroxyl radicals (OH), singlet oxygen ( 1 O 2 ), and superoxide (O 2 •− ) anion [ 11 ]. Arsenic is one of the most dangerous metalloids for plant health and its detrimental effects disrupt metabolic and physiological responses in plants, such as plant growth [ 4 ], ROS accretion [ 9 ], and photosynthetic repercussions [ 9 ].…”

“…The minimization of As-accumulation, as well the as strengthening of the antioxidant system, have been suggested the two primary strategies for sustaining proper growth and development in plants under As stress [ 1 , 3 ]. Plants use and employ strategies to counter the metal/metalloid stress, including chelation (phytochelatins; PCs), osmolyte accumulation (proline), an antioxidant such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), and non-enzymatic antioxidants, including glutathione (GSH) andascorbate (AsA) [ 11 ].…”

Impact of Nitrogen and Sulfur Applications on Seed Yield, Protein, Oil Content, and Fatty Acid Composition of Canola (Brassica napus L.)

“…16,21,26 Moreover, sulfur(S) is an essential component for the growth of the Cruciferae family, particularly Brassica napus and Brassica juncea, which have high S requirements due to their high protein and glucosinolate contents. 20 S is a constituent of amino acids cysteine and methionine needed for protein synthesis in canola. 28 Also, S serves a vital environmental role for many plants via protecting them against herbivores and diseases.…”