Physio-anatomical modifications and element allocation pattern in Alternanthera tenella Colla. associated with phytoextraction of chromium

Abstract

Intensive industrial activities increased the concentration of chromium in the environment especially in the soil and water, which pose serious threat due to its cytotoxic and carcinogenic nature. Phytoremediation has evolved as an eco-friendly, cost-effective alternative for the decontamination of pollutants, and an attempt has been made to reveal the potential of Cr remediation by an invasive plant, Alternanthera tenella Colla in the present study. The morphological, anatomical and physiological modifications of plant tissues in response to 240 µM of K2Cr2O7 is studied, with reference to the elemental distribution pattern and bioaccumulation potential. Assessment of growth parameters showed that Cr adversely affects the elongation of root and shoot, leaf area, and dry biomass weight. Cr influence the macro and micro-elemental distribution in plant tissues specially in roots and leaves. Plants exhibited structural modifications like increase in the thickness and diameter of the xylem walls in the root, stem and leaf tissues of Cr treated A. tenella. Presence of cell structural distortions and Cr deposit inclusions in the xylem wall and the inner parenchyma cells were distinct. Cr stress induced the reduction in pigment content and metabolites like proteins and soluble sugars, while proline, phenol and malondialdehyde marked a significant increase. With BCF and TF values greater than 1 and the mechanisms to cope with the metal stress, A. tenella proves to be an ideal candidate for phytoextraction of Cr.