Physiological and biochemical responses, elemental uptake and cadmium accumulation in Celosia cristata L. under cadmium stress

Cadmium (Cd) pollution poses a serious threat to ecology and human health. Many plants of Amaranthus have attracted more attention because of their high Cd enrichment capacity. However, the Cd enrichment of Celosia cristata L. (cockscomb) has not been extensively investigated. Therefore, we studied the physiological and biochemical responses, elemental uptake and Cd enrichment of cockscomb under Cd stress. The results showed that the content of total chlorophyll was proportional to Cd concentration at 10 d, but decreased significantly at 20 and 30 d. The content of oxidized glutathione increased significantly at 10 and 20 d. The bioabsorption coefficients of the mineral elements were sulfur > potassium > magnesium > phosphorus > iron >zinc > copper. The degree of DNA methylation was directly proportional to Cd concentration, reaching 17.63%, 20.34%, 25.61%, and 31.07% at 50-200 mg/kg. It showed that the tolerance mechanism of cockscomb to Cd stress may be related to its absorption of mineral elements and changes of DNA methylation. The Cd enrichment >100 mg/kg, bioconcentration factors and transfer coefficient >1, indicating that cockscomb has high Cd enrichment ability. It is proposed that cockscomb should be applied to the phytoremediation of Cd-contaminated plants, offering ornamental and economic benefits.