ANTIOXIDANT DEFENSE RESPONSE OF ARBUSCULAR MYCORRHIZAL FUNGI AND SETARIA VIRIDIS

Setaria viridis inoculate with Funneliformis mosseae was studied for examining the effects of arbuscular mycorrhizal fungi (AMF) on the growth, antioxidant enzyme activity and metabolites of Setaria viridis under Cadmium stress. The growth index, including root length, plant height and biomass of S. viridis inoculated with F. mosseae under Cd stress were higher than those of S. viridis without inoculation. Inoculation with F. mosseae can increase activities of CAT, SOD, POD and APX in shoot and decrease the activities of NADPH oxidase in root and shoot. The expression of SvRbohF gene encoding NADPH oxidase was down-regulated in roots but up-regulated in shoots. It showed that inoculation with F. mosseae induced the shoot of Setaria viridis to obtain higher antioxidant enzyme activity and scavenge more reactive oxygen species, thus further weakening the oxidative stress response of shoot and maintaining higher shoot biomass. The GSH and Cd content significantly increased in root inoculated with F. mosseae under Cd stress, but the MDA and Cd content in shoot significantly decreased. The changes increasing yield of phytochelatin, immobilizing Cd in root as much as possible, and reducing Cd content in shoot and lipid peroxidation products may be one of the mechanisms of AMF promoting the resistance of Setaria viridis to Cd stress. In addition, two-factor interaction analysis showed that Cd stress and AMF had significant interaction effects on aboveground biomass, CAT and other enzyme activities and Cd content of Setaria viridis. It confirmed that AMF could reduce the damage of Setaria viridis to Cd and promote the growth of Setaria viridis by regulating antioxidant defense system.