Insights into Cadmium Uptake and Changes in Morphophysiological and Biochemical Characteristics of Eclipta alba L., Plants Exposed to Elevated Cadmium in Soil
摘要
Eclipta alba L., a medicinal herb stands out as a valuable source of therapeutic compounds, playing a pivotal role in the treatment of numerous diseases. Accumulation of cadmium (Cd) in various cellular parts could potentially elevate and impact the biochemical, physiological and morphological traits of E. alba, cultivated in Cd-enriched soil under dry tropical climate of India. The present study focuses on understanding the growth dynamics, Cd uptake and its subcellular distribution in E. alba exposed to elevated Cd in soil. A randomized block design experiment was conducted and test plant was treated with Cd doses ranging from 0 to 20 mg L−1 at an interval of a week till the 70 days after the plant transplant (DAT). Enzymatic activities i.e. ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), and superoxide dismutase (SOD), along with non-enzymatic activities such as total phenolics and flavonoids content, lipid peroxidation, proline, and ascorbic acid, significantly increased in Cd-treated plants as compared to the control. Cd primarily accumulated in the cell wall, followed by cytoplasm and least in cell organelles, with proportions of 93%, 11%, and 5%, respectively. In E. alba plants, Cd levels increasing correspondingly with soil Cd and were found highest in the roots (13.4 mg kg−1 dw), followed by the leaves (11.1 mg kg−1 dw) and the stems (9.1 mg kg−1 dw). The root, shoot and total biomass of E. alba were decreased by 58.3%, 51.1% and 52.6%, at 40 DAT under 20 mg Cd kg⁻1 dw, with losses, rising to 68%, 60.2%, and 62.3%, respectively at 70 DAT. Leaf Cd was positively and significantly linked with changes in morpho-physiological and biochemical attributes of E. alba plants. E. alba grows rapidly and yields a large amount of biomass, effectively indicates an environmental pollution by heavy metals, particularly Cd, because it flourishes in high densities along highways polluted with heavy metals in tropical wastelands. The extent of Cd accumulation in E. alba is directly influenced by soil Cd levels and the plant’s uptake and storage mechanisms. This research reveals differential Cd accumulation across the plant tissues, providing key insights into these processes. These findings pave the way for future studies on how Cd impacts the medicinal properties of E. alba, with implications for its use in phytoremediation and sustainable cultivation in contaminated environments.
Graphical Abstract