Unsnarling Plausible Role of Plant Growth-Promoting Rhizobacteria for Mitigating Cd-Toxicity from Plants: An Environmental Safety Aspect

Cadmium (Cd) is predominantly observed within the soil to cause deterioration of plant and microbial activities within rhizosphere. Cd-toxicity leads to major agricultural constraints due to its accumulation within plants and therefore entry within food chain. Plants face numerous repercussions like stunted growth, chlorosis, necrosis, inhibition of photosynthetic machinery and other physiological and biological activities. Utilization of microbial inoculants for Cd-stress tolerance from plants is lucrative for agricultural practices in order to enhance their productivity and yield. The presence of microorganisms in rhizosphere is of utmost importance as they interact with plants in direct and indirect ways through signalling mechanisms. They are quintessential in improving nutrient uptake and reducing ill effects of metal ions through detoxification, transformation and secreting certain volatile organic compounds that inhibit survival of pathogens near plants. The rhizobacteria possess plant growth-promoting characteristics in terms of improved enzyme activities, nitrogen fixation and phytohormones (Indole-3-acetic acid (IAA), gibberellins (GA), cytokinins (CK), ethylene (ET), 1-aminocyclopropane-1-carboxylate (ACC) deaminase etc.), siderophores and chelating agents. Furthermore, microbes are acquired with specific mechanisms against metal ions such as efflux, immobilization, stabilization, complexation, volatilization, sequestration and detoxification of different Cd-ions. Therefore, descriptive understanding of plant growth-promoting microorganisms (PGPM) favours their exploration as biofertilizers for sustainable agriculture through successful commercialization of strains.

Automated summary

The presence of cadmium in soil can negatively impact plant and microbial activities, affecting plant growth and leading to agricultural constraints. However, microbial inoculants can help plants tolerate cadmium stress and enhance productivity. Microorganisms in the rhizosphere interact with plants through signaling mechanisms, aiding in plant growth and improving nutrient uptake.