Phytoremediation ability and selected genetic transcription in Hydrocotyle umbellata-under cadmium stress

Cadmium (Cd) is the most toxic element which may cause serious consequences to microbial communities, animals, and plants. The use of green technologies like phytoremediation employs plants with high biomass and metal tolerance to extract toxic metals from their rooting zones. In the present work, Hydrocotyle umbellata was exposed to five Cd concentrations (2, 4, 6, 8, and 10 µmol) in triplicates to judge its phytoextraction ability. Effects of metal exposure on chlorophyll (Chl), bio-concentration factor (BCF), translocation factor (TF), and electrolyte leakage (EL) were analyzed after 10 days of treatment. Metal-responding genes were also observed through transcriptomic analysis. Roots were the primary organs for cadmium accumulation followed by stolon and leaves. There was an increase in EL. Plants showed various symptoms under increasing metal stress namely, chlorosis, browning of the leaf margins, burn-like areas on the leaves, and stunted growth, suggesting a positive relationship between EL, and programmed cell death (PCD). Metal-responsive genes, including glutathione, expansin, and cystatin were equally expressed. The phytoextraction capacity and adaptability of H. umbellata L. against Cd metal stress was also demonstrated by BCF more than 1 and TF less than 1.