Cadmium accumulation, sub-cellular distribution and interactions with trace metals (Cu, Zn, Fe, Mn) in different rice varieties under Cd stress.

Rice (Oryza sativa L.) is a staple food in most Asian countries, although it serves as a significant carrier of cadmium (Cd) accumulation. Developing low-Cd accumulating rice varieties is crucial for minimizing Cd contamination in soil and rice grains while also mitigating harmful health consequences. In the present study examined the Cd accumulation and sub-cellular distribution of both high Cd (IR-50) and low Cd (White Ponni) rice varieties under Cd-treated hydroponic nutrient solutions. The results showed that under all Cd treatments, overall plant height, plant fresh and dry biomass reduced substantially in both rice varieties compared to the control. Both rice varieties accumulated more Cd in their roots than shoots, with IR-50 accumulating higher Cd levels. Iron (Fe) concentrations were higher in both roots and shoots of both rice varieties compared to other trace elements. Translocation factor (TF) values were < 1, indicating limited Cd translocation from roots to shoots. Cd was mainly distributed in the epidermis, cortex, and bulliform cells of both rice varieties roots, and shoots. The peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) enzymes activity significantly increased in both IR-50 and WP rice varieties when exposed to Cd treatment. The current study concluded that the IR-50 rice variety accumulated and distributed more Cd than the WP rice variety under different Cd treatments. As a result, WP exhibited higher Cd tolerance, while IR-50 became more susceptible to Cd stress.