Effective Microorganisms Improve Growth Performance and Modulate the ROS-Scavenging System in Common Bean (Phaseolus vulgaris L.) Plants Exposed to Salinity Stress

Abstract

No information is available concerning effective microorganisms’ (EM) influence on the ROS-scavenging system under saline conditions. Thus, as a first approach, the present study evaluates the effect of EM on antioxidant machinery, and also visualizes the interrelationship between EM and salinity stress response components. Phaseolus vulgaris cv. Nebraska plants were grown under non-saline or saline conditions (2.5 and 5.0 dS m−1) with and without EM application. Plants exposed to soil salinity exhibited a significant decline in growth, productivity and membrane stability index. However, the follow-up treatment with EM detoxified the stress generated by salinity and significantly improved the above parameters. The concentrations of proline and glycinebetaine, the activities of antioxidative enzymes (superoxide dismutase, peroxidase, catalase and glutathione reductase), and the contents of antioxidant molecules (glutathione, ascorbate, phenols and anthocyanins) were increased under saline conditions; these increases were more significant in salt-stressed plants treated with EM. Soil salinization induced oxidative damage through increased lipid peroxidation, electrolyte leakage and hydrogen peroxide levels. EM application altered plant physiology and significantly reduced the oxidative damage. Both the prevention of oxidative stress and the elimination of ROS can be one of the most effective mechanisms used by EM-treated plants to gain tolerance against salinity stress. Indeed, with this biological strategy plants find protection from the deleterious effects of oxidants and cope with salty soils.