The role of taurine in modulating metal accumulation and gene expression under cadmium stress in Glycyrrhiza glabra

Heavy metal pollution, particularly cadmium (Cd), poses a significant threat to the environment, human health and plant growth. Taurine is an amino acid with antioxidant properties. The effect of taurine on Cd- induced stress in licorice (Glycyrrhiza glabra L.) plants remains unexplored. Thirty-day-old seedlings were treated with Cd chloride solution (0.200 μM) and taurine (0.10 gL-1). After 2 weeks, desired factors including Cd accumulation, plant pigments, enzyme activities (peroxidase, superoxide dismutase, catalase), malondialdehyde, H2O2, and relative expression of Metl (Metallothionein) and CYP88D6 (Cytochrome P450 Family 88 Subfamily D Member 6) genes, were studied. Results revealed that licorice are able to accumulate Cd in root and shoot without any impact on growth while taurine reduced Cd accumulation significantly. Taurine increased chlorophyll and carotenoid levels, while Cd had varied effects on plant pigments. Taurine decreased malondialdehyde levels, peroxidase and superoxide dismutase activities. Taurine did not affect H2O2 content. Gene expression analysis showed increased expression of the Metl and CYP88D6 genes under taurine treatment. The results of this study indicate that taurine treatment can mitigate the toxic effects of Cd on licorice plants, leading to improved growth, reduced oxidative stress, and enhancing biosynthesis of the secondary metabolite glycyrrhizin by altering gene expression. Taurine may have potential applications in mitigating heavy metal stress in plants. Application of taurine in agricultural practices would be an efficient strategy to combat heavy metal pollution and ensure food safety.