Inhibition Roles of Calcium in Cadmium Uptake and Translocation in Rice: A Review

Abstract

Cadmium (Cd) contamination in rice grains is posing a significant threat to global food security. To restrict the transport of Cd in the soil-rice system, an efficient way is to use the ionomics strategy. Since calcium (Ca) and Cd have similar ionic radii, their uptake and translocation may be linked in multiple aspects in rice. However, the underlying antagonistic mechanisms are still not fully understood. Therefore, we first summarized the current knowledge on the physiological and molecular footprints of Cd translocation in plants and then explored the potential antagonistic points between Ca and Cd in rice, including exchange adsorption on roots, plant cell-wall composition, co-transporter gene expression, and transpiration inhibition. This review provides suggestions for Ca/Cd interaction studies on rice and introduces ionomics research as a means of better controlling the accumulation of Cd in plants.

Seed Priming with Silver Ions Improves Growth and Physicochemical Features of Rice Plants (Oryza sativa L.) under Copper Stress

“…The concentrations of Ca (15.1%), Mg (10.2%), and Fe (14.9%) in the shoots of Ag10 were significantly ( p < 0.05) increased compared to Ag0, and the concentrations of Ca (21.0%), Mg (29.1%), and Mn (37.0%) in the roots of Ag10 were significantly ( p < 0.05) increased compared to Ag0 (Figure S4). Ca 2+ is an important intracellular signal transducer in rice cells that transmits stimuli due to heavy metal stress and thus promotes the initiation of plant defense responses and also is a component of the cell wall and stabilizes the pectin content of the cell wall . Increased Ca 2+ uptake enhances the response of rice cells to Cu stress as well as the chelating capacity of the cell wall for Cu (Figures b,c and S6).…”

“…Ca 2+ is an important intracellular signal transducer in rice cells that transmits stimuli due to heavy metal stress and thus promotes the initiation of plant defense responses 39 and also is a component of the cell wall and stabilizes the pectin content of the cell wall. 40 Increased Ca 2+ uptake enhances the response of rice cells to Cu stress as well as the chelating capacity of the cell wall for Cu (Figures 2b,c and S6). Given that Mg is an important component of chlorophyll and Fe is an essential cofactor of the cytochrome complex, 3,41 the higher contents of Mg and Fe in the shoots of Ag10 contributed to its higher chlorophyll content, consistent with its higher net photosynthesis rate (Figure 1b,c).…”