Sveta Thakur

Plant-driven removal of heavy metals from soil: uptake, translocation, tolerance mechanism, challenges, and future perspectives

Increasing heavy metal (HM) concentrations in the soil have become a significant problem in the modern industrialized world due to several anthropogenic activities. Heavy metals (HMs) are non-biodegradable and have long biological half lives; thus, once entered in food chain, their concentrations keep on increasing through biomagnification. The increased concentrations of heavy metals ultimately pose threat on human life also. The one captivating solution for this problem is to use green plants for HM removal from soil and render it harmless and reusable. Although this green technology called phytoremediation has many advantages over conventional methods of HM removal from soils, there are also many challenges that need to be addressed before making this technique practically feasible and useful on a large scale. In this review, we discuss the mechanisms of HM uptake, transport, and plant tolerance mechanisms to cope with increased HM concentrations. This review article also comprehensively discusses the advantages, major challenges, and future perspectives of phytoremediation of heavy metals from the soil.

Lead induced oxidative stress and alteration in the activities of antioxidative enzymes in rice shoots

Physiological responses of Oryza sativa L. to lead excess (10 and 50 μM) were studied in a hydroponic system after 48- and 96-h exposure. Accumulation of Pb in stressed rice shoots was concomitant with an increased metal concentration in the growth media and duration of exposure. The Pb stress resulted in an enhanced lipid peroxidation accompanied by altered activities of antioxidants. A substantial increase in α-tocopherol content of the Pb stressed rice shoots was observed suggesting its important role as an antioxidant. Among the antioxidant enzymes studied, activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) increased in the Pb-treated rice shoots, whereas that of catalase (CAT) declined. Activity of an important ascorbate-glutathione cycle enzyme, glutathione reductase (GR), also increased significantly in the Pb-treated shoots. The results suggest that Pb toxicity resulted in induction of oxidative stress in rice shoots, and α-tocopherol accumulation and upregulation of SOD, APX, and GR activities play an effective role in acclimatization to Pb stress.