Climate change is causing soil salinization, resulting in crop losses throughout the world. The ability of plants to tolerate salt stress is determined by multiple biochemical and molecular pathways. Here we discuss physiological, biochemical, and cellular modulations in plants in response to salt stress. Knowledge of these modulations can assist in assessing salt tolerance potential and the mechanisms underlying salinity tolerance in plants. Salinity-induced cellular damage is highly correlated with generation of reactive oxygen species, ionic imbalance, osmotic damage, and reduced relative water content. Accelerated antioxidant activities and osmotic adjustment by the formation of organic and inorganic osmolytes are significant and effective salinity tolerance mechanisms for crop plants. In addition, polyamines improve salt tolerance by regulating various physiological mechanisms, including rhizogenesis, somatic embryogenesis, maintenance of cell pH, and ionic homeostasis. This research project focuses on three strategies to augment salinity tolerance capacity in agricultural crops: salinity-induced alterations in signaling pathways; signaling of phytohormones, ion channels, and biosensors; and expression of ion transporter genes in crop plants (especially in comparison to halophytes).

CeO₂NPs displayed concentration and coating property dependent effects on soybean photosynthesis and water use efficiency.

Cadmium (Cd) is a metal toxic to humans even at very low concentrations. Elevated levels of Cd in soil due to various anthropogenic activities have led to higher Cd concentrations in various crop tissues, making it a food safety concern. With the progressive production and continued accumulation of engineered nanoparticles (ENPs) in agricultural soils, understanding the effect of ENPs on the uptake and accumulation of metals by plants is imperative. The goal of this study was to determine the mutual effects of cerium oxide nanoparticles (CeO₂NPs) and Cd²⁺ on their uptake and accumulation by soybean seedlings (Glycine max (L.) Merr.) in a hydroponic system. Soybean seedlings were exposed to four treatments (1.0 mg L⁻¹ Cd²⁺, 1.0 mg L⁻¹ Cd²⁺ + 100 mg L⁻¹ CeO₂NPs, 100 mg L⁻¹ CeO₂NPs and 0 mg L⁻¹ Cd and CeO₂NPs as the control) for 10 days. At termination, plant roots and shoots were separated and the concentrations of Cd and Ce in these tissues were determined. In addition, the amounts of ionic Ce and particulate Ce within soybean roots were determined. Significant interactions between co-existing CeO₂NPs and Cd were found with regard to their accumulation in plant tissues. While CeO₂NPs did not affect the total Cd associated with soybean roots, they significantly reduced the translocation of Cd from roots to shoots by 70%. In contrast, the co-presence of Cd lowered the concentration of Ce in soybean roots by 45% but significantly increased the concentration of Ce in soybean shoots by 60%. The altered plant accumulation of co-existing Cd and Ce was attributed to various physical, chemical and biological processes that occurred in the plant rhizosphere. Specifically, the co-presence of Cd and CeO₂NPs led to higher excretion of plant root exudates, which might have altered the chemical environment in the plant rhizosphere and enhanced CeO₂NP dissolution, leading to different plant accumulation of both chemicals.