Role of nanoparticles in mitigating chromium toxicity: implications, mechanisms, andfuture prospects

Chromium (Cr) is an extremely toxic metal for all living organisms and its concentration in the environment is constantly increasing due to human activities. Plants quickly absorb Cr. Subsequently, it enters the human food chain and poses serious health risks. Chromium toxicity causes a significant reduction in plant growth by inducing oxidative damage and disturbing protein synthesis, enzyme activity, and nutrient uptake. Plants use diverse mechanisms to mitigate Cr toxicity; however, they are inadequate in the face of higher concentrations of Cr. Thus, it is essential to decrease Cr toxicity and increase the ability of plants to tolerate Cr stress. Nanoparticles (NPs) mitigate the toxicity of Cr by reducing its uptake and accumulation and improving antioxidant activities, nutrient homeostasis, photosynthetic efficiency, osmolyte synthesis, and hormonal balance. The complex interactions between NPs and microbes, signaling molecules, and hormones also significantly counter Cr toxicity. The present review discusses the various mechanisms of NPs for mitigating Cr toxicity. This review also addresses various research gaps to encourage the better utilization of NPs to mitigate Cr toxicity and improve crop growth and yield. This review offers new insights into the role of NPs in mitigating Cr toxicity.