Progesterone and brassinosteroids synergistically enhance progesterone removal and antioxidant capacity of Solanum nigrum L.

Progesterone (PROG) has been detected at various concentrations in the environment and has adverse effects on humans and wildlife. This work evaluated the impact of PROG in Solanum nigrum L. plants, its removal capacity, and how 2,4-epibrassinolide (24-EBL) affects this process. Three treatments were used: (1) control, (2) irrigation with 0.8 µM PROG, and (3) treatment with 0.8 µM PROG after a pre-treatment with a foliar application of 1 µM 2,4-EBL (PROG/24EBL). After 20 days of treatment, no PROG was detected in the nutrient solution or plant tissues, indicating that the PROG was removed and metabolized. Lipid peroxidation significantly decreased in response to PROG in shoots and roots, and this effect was even more significant for both organs of the PROG/24EBL plants. Additionally, both treatments in both organs showed a decrease in H₂O₂ levels, and both steroid hormones increased the plants’ antioxidant system at both the biochemical and gene expression levels. In conclusion, S. nigrum can swiftly remove PROG without affecting its growth, and the use of 24-EBL synergistically decreases oxidative damage by increasing the activity of the antioxidant system and enhancing plant PROG removal ability.