Inoculation with a bacterial consortium alleviates the effect of cadmium overdose in soybean plants

Abstract

Inoculating plants that have inefficient antioxidant systems with plant-associated bacteria allows them to overcome heavy metal intoxication. We monitored protein oxidation, the activity of plant defense system enzymes, and the phenolics content in soybean (Glycine max L.) during a prolonged exposure to cadmium (Cd). The assistance of the bacterial consortium reduced the bioavailability of Cd in a soil containing 10 times the metal's Standard Maximum Value (SMV). This reduced the accumulation of Cd in the soybeans' roots and seeds. At 100 SMV, bacterial inoculation resulted in increased Cd bioavailability, which enhanced cadmium uptake by the soybean plants. At both Cd concentrations, oxidative stress was more prolonged in the soybean's roots than its leaves. In cadmiumpolluted soil, glutathionе peroxidase activity changed more rapidly in the roots of plants when they had been inoculated. Inhibition of the peroxidases' activities strengthened the activity of glutathione-S-transferase; increased the phenolics content in plant roots; and alleviated stress in inoculated soybean plants compared to untreated plants. The bacterial consortium may be recommended for a plant protection at 10 SMV Cd in the soil, and for phytostabilization at 100 SMV.© Versita Sp. z o.o.

Microbial Fortification Improved Photosynthetic Efficiency and Secondary Metabolism in Lycopersicon esculentum Plants Under Cd Stress

“…However, an increase in the level of total phenolics was also observed by inoculation of P. aeruginosa in wheat plants exposed to Zn stress as a protective action [80]. The induced antioxidant mechanism through higher accumulation of total phenols was also found in soybean plants under Cd exposure [81]. They revealed that accumulation of phenolic compounds in leaves and roots are mainly due to oxidative polymerization of enzymes involved in phenylpropanoid pathway that further alters the permeability of cell wall [81].…”

“…The induced antioxidant mechanism through higher accumulation of total phenols was also found in soybean plants under Cd exposure [81]. They revealed that accumulation of phenolic compounds in leaves and roots are mainly due to oxidative polymerization of enzymes involved in phenylpropanoid pathway that further alters the permeability of cell wall [81]. The most possible mechanism involved behind the microbe-mediated stimulation of phenolic compounds in the present study is that microbes actively participate in shikimate pathway of phenol biosynthesis during stressed conditions [82].…”

<i>Pantoea agglomerans</i>: a mysterious bacterium of evil and good. Part IV. Beneficial effects

“…According to Xiong et al [151], with permission a high adsorption capacity for heavy metal ions Cr(VI), Cd(II) and Cu(II), creating a promising perspective for the effective treatment of wastewater polluted with toxic metals. P. agglomerans was also among 7 strains which were proved by Zaets et al [163] to be effective in the protection of soybean plants against accumulation of toxic cadmium present in soil. Similarly, Pishchik et al [164] demonstrated that inoculation of P. agglomerans into soil highly contaminated with toxic cadmium and lead resulted in a decrease of their content by 2-3 times and 4-5 times, respectively, and furthermore, caused a significant increase of the oats yield which exceeded even the yield noted in soils not contaminated with heavy metals.…”

Recent progress on the microbial mitigation of heavy metal stress in soybean: overview and implications

“…The plants were protected from heavy metal stress due to the activation of phenolic compounds and glutathione-S-transfers. The results suggest that microbial inoculation significantly enhanced the antioxidant activity of 10 SMV in Cd soil ( Zaets et al., 2010 ).…”