Assessment of the Cadmium and Copper Phytoremediation Potential of the <i>Lobularia maritima Thioredoxin 2</i> Gene Using Genetically Engineered Tobacco
2023
Rania Ben Saad | Walid Ben Romdhane | Narjes Baazaoui | Mohamed Taieb Bouteraa | Anis Ben Hsouna | Avinash Mishra | Sanja Ćavar Zeljković
Rapid global modernization, urbanization, and industrialization have accelerated the release of heavy metals, causing soil pollution. These highly noxious environmental pollutants induce oxidative stress in plants via stimulation of the production of reactive oxygen species (ROS). Thioredoxin (Trxs) is a highly conserved disulfide reductase that plays a crucial role in intracellular redox homeostasis in both eukaryotes and prokaryotes. Herein, the presence of heavy metals highly upregulated <i>LmTrxh2</i> transcription in <i>Lobularia maritima</i> seedlings and its overexpression-conferred tolerance to Cd, Cu, Mn, and Zn in <i>Saccharomyces cerevisiae</i>. In addition, <i>LmTrxh2</i>-overexpressing tobacco plants had higher seedling survival rates than non-transgenic plants (NT), with enhanced root length and biomass production and reduced ROS accumulation, following Cd and Cu stress. These plants also accumulated more Cd, Cu, and Mn than the NT plants. Moreover, <i>LmTrxh2</i> overexpression stimulated the transcription of genes encoding metallothioneins (<i>Met-1</i>, <i>Met-2</i>, <i>Met-3</i>, and <i>Met-4</i>), a copper transport protein, a Snakin/GASA protein (<i>Snakin-2</i>), and ROS-scavenging enzymes (<i>SOD</i>, <i>APX1</i>, and CAT), which might contribute to heavy metal tolerance in tobacco plants. These results suggest that <i>LmTrxh2</i> overexpression helps to improve heavy metal tolerance by stimulating antioxidant capacities and the expression of several stress-responsive genes in plants.
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