Genotypic variation of rice plants exposed to cadmium (109Cd): nutritional, biochemical and ultrastructural assessment

Abstract

Cadmium (Cd) is a toxic element to plants, animals and humans. Cd is particularly dangerous due to its relatively high mobility in soils and transfer to plants. Moreover, plants growing in contaminated soils can accumulate Cd in edible tissues in large quantities without any visible signs. Due to the increasing concern about the intake of Cd in foods, the risks of its potential entry into the food chain need to be carefully considered. The objectives of this research are: (i) to identify rice genotypes that are more tolerant to the toxic effects of Cd and exhibit less potential for its accumulation into the grain and (ii) to characterize and relate the nutritional, biochemical and ultrastructural parameters in rice cultivars exposed to Cd using the radioisotope 109Cd as a tracer in the soil-plant system. Two experiments will be carried out in a greenhouse using three rice cultivars with characteristics of low (Cateto seda), medium (BRSMG Talento) and high (BRSMG Relâmpago) capacity of Cd uptake, cultivated in pots filled with 3 kg of Oxisol samples. The cultivars will be exposed to five levels of Cd (0.65, 1.3, 3.9, 6.5, and 11.7 mg kg-1) in the first experiment and two levels of Cd (1.3 and 11.7 mg kg-1) in the second experiment. A control treatment (no Cd addition) will be included in each experiment. In this project, the growth and distribution of Cd in parts of the rice plants and the concentration of nutrients, lipid peroxidation, hydrogen peroxide, ascorbic acid, reduced glutathione, activity of antioxidant enzymes and ultrastructural analysis of leaf tissues will be compared. The experiment will be arranged in a completely randomized block design with four replicates. The data will be statistically analyzed using analysis of variance, Tukey's test, correlation, and polynomial regression.