Effects of arbuscular mycorrhizal fungi on redox homeostasis of rice under Cd stress

Abstract

Arbuscular mycorrhizal fungi (AMF) can enhance cadmium (Cd) tolerance and decrease Cd uptake of rice plant. However, in these processes, the essential role of reactive oxygen species (ROS)-antioxidants interactions is so far not investigated. We inoculated AMF, Funneliformis mosseae (Fm) and Rhizophagus intraradices (Ri), to upland rice subjected to 0, 2 or 10 mg Cd kg−1 in soil. ROS, antioxidants, chlorophyll, mesophyll cell ultrastructure, Cd concentration and Cd transporters were measured. Results showed that the levels of ROS (i.e., superoxide, hydrogen peroxide and lipid peroxidation) were mitigated in +AMF + Cd treatments, especially in +Ri + Cd, compared with −AMF + Cd. For antioxidants, lower levels of catalase, peroxidase and superoxide dismutase, whereas higher levels of glutathione and glutathione peroxidase were observed in +AMF + Cd compared with −AMF + Cd. Chlorophyll content and mesophyll cell ultrastructure were improved by AMF. Cd concentrations in plants were significantly decreased in +AMF + Cd (10 mg Cd kg−1) treatments. AMF not only decreased Cd accumulation in rice but also regulated the ROS scavenging activities. The variations of ROS and antioxidants were restrained to smaller ranges by AMF. AMF may assist in Cd restriction and thus helping the host to release glutathione for ROS scavenging.