Phosphate-solubilizing bacteria enhance lead extraction efficiency by Artemisia annua L.: insights into...

Phosphate-solubilizing bacteria (PSB) combined with plants for heavy metal phytoextraction is a promising remediation strategy for lead (Pb)-contaminated soils, yet the intrinsic mechanisms remain not fully elucidated. Thus, this study inoculated the PSB strain Leclercia adecarboxylata L1-5 into the rhizosphere of Artemisia annua L. to investigate its regulatory effects on soil Pb extraction. The results showed that PSB inoculation significantly enhanced the Pb extraction efficiency of A. annua L., with a 96.72% increase compared to the control group. Additionally, the above-ground biomass and root biomass of A. annua L. increased by 51.39% and 155.22%, respectively. Chlorophyll a and chlorophyll b contents increased from 0.30 mg · g⁻¹ FW and 0.44 mg · g⁻¹ FW to 1.55 mg · g⁻¹ FW and 1.50 mg · g⁻¹ FW, respectively, with a 51.56% increase of the C_a/C_b ratio, suggesting that PSB improved plant growth and chlorophyll synthesis. Transmission electron microscopy revealed that PSB inoculation reduced ultrastructural damage of the plant leaves. Furthermore, the activities of key antioxidant enzymes-superoxide dismutase, catalase, and peroxidase-increased by 155.95%, 271.23%, and 192.55%, respectively, suggesting that PSB reduced Pb-induced oxidative stress in the plants. These findings provide new insights into the proof of the combined effect of PSB and A. annua L. and underscore their promising translational potential for the sustainable remediation of heavy metal-contaminated soils.