Investigating heavy metal accumulation and oxidative stress tolerance of non-accumulators and hyperaccumulators in the Brassicaceae plant family

Physiological and enzymatic analysis indicated that the non–accumulator A. thaliana showed an oxidative stress response in all assays except for protein carbonylation. Other non–accumulator plant species showed a significant difference in oxidative stress response in the TBARS assay, however, for some assays no stress response was evident. The hyperaccumulator plant species showed no significant difference in oxidative stress as indicated by the all of the assays with the exception of T. montanum var. montanum which showed an oxidative stress response in the SOD assay. Basal catalase enzyme activity was notably higher in the hyperaccumulators T. montanum var. montanum and T. montanum var. siskyiouense as compared to the non-accumulator A. thaliana. Results of the oxidative stress assays were also compared to the levels of nickel present in the various plant species. These experiments show that hyperaccumulators may have additional mechanisms that allow them to resist oxidative stress more effectively than non-accumulators.