Role of arbuscular mycorrhiza in arresting reactive oxygen species (ROS) and strengthening antioxidant defense in Cajanus cajan (L.) Millsp. nodules under salinity (NaCl) and cadmium (Cd) stress
2015
Garg, Neera | Chandel, Shikha
Application of phosphate fertilizers and biosolids enhances Cd contamination in arid and semi-arid regions. Increased concentration of dissolved chloride (Cl⁻) in saline solution increases Cd solubility and bioavailability. Nodules are soft targets for NaCl and Cd stresses due to adverse effects on their functioning. Arbuscular mycorrhizal (AM) fungi enhance plant growth in contaminated sites. Greenhouse experiments were conducted to evaluate the efficacy of Funneliformis mosseae in arresting toxic ion transport and ROS generation in pigeonpea nodules and its role in improving membrane structure and antioxidant defense. Two genotypes (Sel 85N; tolerant and ICP 13997; sensitive) were subjected to NaCl (4, 6 dS m⁻¹) and Cd (CdCl₂—25, 50 mg Kg⁻¹dry soil) treatments. Results indicated higher phytotoxicity of Cd than NaCl which aggravated when NaCl was added along with Cd. Increment in toxic ions caused injury to nodular membranes and increased oxidative stress (H₂O₂and MDA), higher in ICP 13997 than Sel 85N. Significant increase in non-protein thiols (NP-SH) and PC levels was observed under Cd and NaCl + Cd treatments. The rapid generation of ROS was counteracted by AM-induced enzymatic activities (SOD, POD, CAT and GR), non-enzymatic components (GSH–GSSG cycling, their ratio and total glutathione) and glutathione-mediated PC synthesis.
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