Arbuscular Mycorrhizal Fungi Enhance Antioxidant Defense Systems in Sugarcane Under Soil Cadmium Stress

Cadmium (Cd) is a toxic metal that affects living organisms even at low concentrations, causing physiological alterations and biomass reduction in plants. Arbuscular mycorrhizal fungi (AMF) represent a biological strategy that increases tolerance to heavy metals, although their specific mechanisms in sugarcane remain poorly understood. To address this knowledge gap, an open-field experiment was conducted to evaluate the effects of AMF on Cd accumulation, oxidative stress, photosynthetic pigments, enzymatic antioxidant system, and non-enzymatic antioxidant compounds in sugarcane variety CC 01-1940, using a randomized block design. Results showed that AMF established symbiosis with plants, retaining Cd in the roots and reducing its translocation to leaves. Additionally, they decreased Cd-induced oxidative stress by reducing lipid peroxidation (MDA) and proline content. Although an initial decrease in photosynthetic capacity was observed, AMF helped maintain stable levels of photosynthetic pigments, preserving photosynthetic efficiency. They also activated antioxidant enzymes and increased antioxidant compounds such as reduced glutathione (GSH), non-protein thiols (NP-SH), ascorbic acid (AA), and phytochelatins (PC). These findings demonstrate that symbiosis with AMF protects sugarcane plants from cellular oxidative damage and reduces Cd concentrations in leaves. Therefore, the use of AMF represents an effective strategy to improve the antioxidant defense and resistance of sugarcane plants to cadmium stress.