Biomarker responses of rice plants growing in a potentially toxic element polluted region: A case study in the Le'An Region

•Toxic element accumulation shows different capacity among different stages.•Multi-biomarker responses vary among different growing stages of paddy.•Toxic elements induce different biomarker response patterns.•Early stage is the most sensitive stage for pollutant stress.•IBRs index response well with toxic element concentrations.

Rice plants, planted and grown in the field, were chosen in this study to evaluate the potentially toxic element pollution by combining pollutant analysis and a molecular biomarker response evaluation together in the Le'An Region, a highly polluted area due to anthropogenic activities. Soils and crops at 18 sites classified into four areas based on hydrological, geological and pollutant survey results were collected during the whole growth cycle for chemical and biological analysis. Sediment quality values and pollution indexes were combined with statistical analyses to assess the hazard of potentially toxic elements and evaluate ecological risks. As effective stress-related signals, chlorophyll (Chl), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), glutathione content (GSH) and lipoperoxidation (as TBARS) were also determined during the rice plant growth period. The results revealed that heavy metal concentrations were significantly higher than corresponding background values and significantly related to those of the soils. The maximum concentration of potentially toxic elements was observed at the tillering stage, followed by the grain filling stage and heading stage. As biomarkers in field monitoring, a significant increase or decrease in Chl, SOD, POD, CAT, GSH and TBARS in crops means a potential relationship between the indexes and pollutants. This study also demonstrates that the integrated biomarker response (IBR) calculated by combining different biomarkers could be used effectively to evaluate the pollutant-induced stress levels in different areas.

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