Exogenous strigolactone improves the cadmium accumulation in Solanum nigrum var. humile

The effects of exogenous strigolactone (using strigolactone analog GR24) on the cadmium (Cd) accumulation in Solanum nigrum var. humile were studied by a pot experiment. The Cd treatment (0.1 mg/L) inhibited the growth of S. nigrum var. humile, indicating that 0.1 mg/L produced the stress to S. nigrum var. humile. Spraying GR24 at 1 mu mol/L did not change plant dry biomass, increased the photosynthetic pigment content and catalase activity, and decreased the peroxidase activity under Cd stress. By contrast, spraying GR24 at 2 mu mol/L had no significant effects on these parameters. The superoxide dismutase activity was decreased by GR24 at 1 mu mol/L, but increased by GR24 at 2 mu mol/L. Nevertheless, both GR24 at 1 and 2 mu mol/L increased the Cd contents, bioconcentration factors, and Cd extractions in various plant organs. Compared to Cd treatment, GR24 at 1 and 2 mu mol/L increased the shoot Cd extraction by 20.0% and 14.5%, respectively. So, application of exogenous strigolactone could improve the phytoremediation capacity of S. nigrum var. humile. Correlation and grey relational analyses showed that the root Cd content, shoot Cd content, and root Cd extraction were the top three parameters closely related to the shoot Cd extraction. These findings suggest that exogenous strigolactone can effectively promote the Cd accumulation in S. nigrum var. humile, presenting a promising solution to enhance its phytoremediation capacity.