Heavy metal accumulation and antioxidant properties of Nephrolepis biserrata growing in heavy metal-contaminated soil

Antioxidant defense mechanisms are crucial for plants to survive under stress conditions. We investigated the capacity of a wild fern species, Nephrolepis biserrata, growing in the vicinity of industrial land to accumulate heavy metals, and assessed its antioxidative response under metal stress. The soils in this particular area were highly contaminated with zinc followed by lead and copper. As control, N. biserrata located 10 km away from the industrial area were collected and assessed. N. biserrata from the contaminated sites accumulated metals in their tissues in similar descending order of zinc>lead>copper. The values of bioaccumulation factor between 0 to 0.1 indicate N. biserrata as a moderate accumulator for the tested metals. For the enzymatic antioxidant assays, the activities of catalase and ascorbate peroxidase were significantly higher in N. biserrata from contaminated soil compared to control, while the activity of superoxide dismutase was not differ significantly in plants from both sites. We also detected higher contents of total phenolics and total flavonoids in N. biserrata collected from contaminated site compared to control. Our HPLC analysis revealed higher levels of myricetin and kaempferol in plant samples from the contaminated area. Our study verified the capacity of N. biserrata to scavenge oxygen radicals when exposed to heavy metal stress. Such ability to tolerate stressful condition suggests that the plant is a potential metal phytoremediator.