Unlocking the Green Solution: Synergistic Effects of Progesterone and Brassinosteroids in Enhancing Progesterone Phytoremediation and Antioxidant Capacity of Solanum nigrum L.

Abstract Aims Progesterone (PROG) has been detected in various concentrations in the environment, with adverse effects on humans and wildlife. So, approaches for reducing the accumulation of this steroid in the environment must be studied. This work aimed at evaluating the phytoremediation potential of PROG by Solanum nigrum L. plants and to understand if 2,4 epibrassinolide (24-EBL) could enhance this species’ tolerance or remediation capacities. Methods Three treatments were assembled: 1) control; 2) plants grown in the presence of 0.8 µM PROG; and 3) plants that grew in the presence of 0.8 µM PROG were pre-treated with a foliar application of 10 µM 2,4-EBL (PROG/24 EBL). PROG levels in the nutrient solution, and several antioxidant-related biochemical and molecular endpoints in roots and shoots, were evaluated after 20 days of treatment. Results HPLC-DAD analysis showed that no PROG was detected in the nutrient solution after 20 days of treatment. Lipid peroxidation significantly decreased in response to PROG in shoots and roots and the pretreatment with 24 EBL was even more effective for both organs. Also, a decrease in H2O2 levels was observed in both treatments for shoots and roots. Plus, the exogenous application of both steroid hormones increased the plants’ antioxidant system both at the biochemical and gene expression levels. Conclusions These results show that S. nigrum can rapidly phytoremediate PROG per se with no negative effects to its growth and that the use of 24 EBL synergistically decreases oxidative damage and enhances the PROG removal ability of the plants.