Impact of dual inoculation with Rhizobium and PGPR on growth and antioxidant status of Vicia faba L. under copper stress

Abstract

Plant-growth-promoting bacteria (PGPR) may help reduce the toxicity of heavy metals in plants in polluted environments. In this work, the effects of dual inoculation with Rhizobium and PGPR strains on the growth of Vicia faba grown under copper stress were assessed during hydroponic culture. Growth parameters, copper (Cu) accumulation and antioxidant enzyme activities were studied. Copper concentrations above 1mM damaged plant growth, but co-inoculation reduced its harmful effect. Co-inoculation of plants treated with 1mM Cu and 2mM Cu increased the dry weights as compared with Cu-treated and uninoculated plants. However, it decreased copper uptake up to 80% in the roots of 1-mM-Cu-treated plants as compared to non-inoculated control. Copper tolerance in Vicia faba is linked to the activity of antioxidant systems that are modulated by metal concentrations: both superoxide dismutase (SOD) and catalase (CAT) were higher in the presence of Cu; a lower Cu dose of 0.5mM stimulated ascorbate peroxidase (APX) and/or peroxidase (POX) activities in shoots and roots; however in nodules CAT appeared to be the main peroxidase in H2O2 scavenging. The 1mM Cu treatment enhanced SOD, CAT and APX activities in roots and only SOD and POX were activated in shoots. All enzyme activities were inhibited by inoculation of 2mM Cu. The effect of inoculation with copper-accumulating PGPRs and the status of the antioxidant enzyme system were linked to changes in the copper tolerance status of Vicia faba. Our results suggested that Vicia faba inoculation with Rhizobium and PGPR Enterobacter clocae and Pseudomonas sp. could help to alleviate copper stress under hydroponic conditions. This result should be tested under field conditions for soil fertilization and phytostabilisation purposes.

Potential of efficient and resistant plant growth‐promoting rhizobacteria in lead uptake and plant defence stimulation in Lathyrus sativus under lead stress

“…Similarly, Fatnassi et al . () and Chiboub et al . () also reported a decrease in lipid peroxidation under heavy metal stress in PGPR‐inoculated plants.…”

“…The obtained results are consistent with others indicating that co‐inoculation with Rhizobium and other PGPR could alleviate the adverse effects of Cu stress on Vicia faba growth (Fatnassi et al . ). In our work, PGPR inoculation improved SOD, GPOX and APX activities in nodules, which served as metal buffer zones, providing extra protection for the plant against invading metal ions and other soluble contaminants (Lebedev et al .…”

The potential of cadmium ion-immobilized Rhizobium pusense KG2 to prevent soybean root from absorbing cadmium in cadmium-contaminated soil

“…It is found that the rhizosphere inoculation of plant growth‐promoting bacteria can increase the SOD activity of plants under heavy metal stress (Fatnassi et al . ; Yu et al . ).…”

“…As an enzymatic scavenger of ROS, SOD provides a defence system for aerobic organisms against environmental stress (Alscher et al 2002). It is found that the rhizosphere inoculation of plant growth-promoting bacteria can increase the SOD activity of plants under heavy metal stress (Fatnassi et al 2015;Yu et al 2017). In this study, the SOD activity of the inoculated soybeans was significantly higher (P < 0Á05, n = 3) than that of the control plants in Cd-contaminated soil, suggesting that the Cd 2+ -removing R. pusense KG2 improved soybean plant tolerance against Cd.…”

HMs Induced Changes on Growth, Antioxidant Enzyme’s Activity, gas Exchange Parameters and Protein Structures in Sasa Kongosanensis f. Aureo – Striatus

“…This could be counted as an essential element in promoting plant growth. In one study, 5 ppm of Cr , and Zn +2 increased the shoot size by 13.0%, 59.0%, 35.0%, and 6.6%, respectively [1], and Ba also showed an effect in low concentrations of Cu in Vicia faba [31]. Overall, in the present study plant growth (i.e., percentage of shoot length and percentage of emerging plants) is shown to have an arc-shaped response to an excess of HMs so that at low concentrations (500 mg/kg), plant growth indexes increased, and then at high concentrations (1,000 mg/kg and 2,000 mg/kg) plant growth indexes decreased.…”