Endogenous Food-Borne Sugar Beet Molasses Carbon Dots for Alleviating the Drought and Salt Stress in Tobacco Plant

Abiotic stress resulting from climate change is still a big global challenge that threatens and heavily affects the agricultural production system leading to significant yield loss. Nanoparticles have proven to be an effective tool to prevent the adverse effects of abiotic stresses. Among them, carbon dots have been found to positively impact plant growth and mitigate the destructive effects of abiotic stresses. Herein, endogenous food-borne carbon dots derived from sugar beet molasses (MCDs) were utilized to investigate their impacts on tobacco plant growth and alleviation of drought and salt stress. For this purpose, six different concentrations of MCDs (0, 10, 25, 50, 100, and 500 mg⋅L−1) were applied to monitor their effects on tobacco plant growth under non-stress, salt, and drought stress conditions. Our findings revealed that MCDs treatment had a positive impact on tobacco growth up to 500 mg⋅L−1 MCDs. Particularly, the utilization of 50 mg⋅L−1 MCDs under drought and salt stress significantly reduced the malondialdehyde (MDA) content of the tobacco plant. The application of 50 and 100 mg⋅L−1 MCDs considerably affected the enhancement of proline content under both stress conditions. The tobacco plant showed an increase in superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), and catalase (CAT) activity with MCDs treatment under drought and salt stresses. In conclusion, MCDs demonstrated a dose-dependent improvement effect on the growth of tobacco plants under salt and drought stresses by improving the antioxidative enzymes (SOD, CAT, APX, and GR) and proline while decreasing MDA levels. Overall, this study suggests that endogenous food-borne MCDs extracted from sugar beet molasses as renewable sources could be a potential agent to protect tobacco plants against drought and salt stresses. Graphical Abstract: [Figure not available: see fulltext.].