Integrated Biochemical and Ultrastructural Responses of Tanacetum vulgare L. to Multi-Metal Stress

Coal combustion at power stations is a significant source of heavy metal accumulation in plants and soil, posing risks to ecosystems and human health. The objective of the study was to investigate the adaptive strategies of common tansy (Tanacetum vulgare L.) exposed to heavy metal pollution in the impact zone of the Novocherkassk State Power Station (Russia). In the impact zone, soil concentrations of Cd, Pb, Ni, Cr, Cu, Zn, and Mn exceeded background levels by 1.4–8.2 times. An analysis of heavy metal translocation revealed selective accumulation mechanisms. The Cd translocation factor increased by 5.6-fold and Pb by 6-fold, correlating with a 14- and 22-fold enrichment of mobile compounds of Cd and Pb in the rhizosphere. T. vulgare demonstrated a coordinated antioxidant response: the activity of superoxide dismutase (+27%), guaiacol peroxidase (+375%), catalase (+348%), as well as the content of glutathione (+11%), increased in shoots. However, the polyphenol content in the shoots decreased by approximately 22%. Despite severe ultrastructural damage, T. vulgare maintained high biomass productivity. This selective translocation phenotype, combined with high biomass productivity, makes the species a promising candidate for the phytoremediation of coal-contaminated soils.