Rhodococcus qingshengii facilitates the phytoextraction of Zn, Cd, Ni, and Pb from soils by Sedum alfredii Hance

• Published in: Journal of hazardous materials 2022-02, Vol.424 (Pt C), p.127638-127638, Article 127638
• Main Authors: Du, Shaoting, Lu, Qi, Liu, Lijuan, Wang, Yu, Li, Jiaxin
• Format: Article
• Language: English
• Subjects: Abscisic acid; Biodegradation, Environmental; Cadmium; Heavy metal; Hyperaccumulator; Lead; Phytoremediation; Rhodococcus; Sedum; Soil; Soil Pollutants - analysis; Zinc
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.127638

The enhanced heavy metal (HM) phytoextraction efficiency of hyperaccumulating plants via plant-growth-promoting microbes has been proposed as an effective strategy to remove HMs from contaminated soil. Nevertheless, it remains unclear whether catabolizing the abscisic acid (ABA) in hyperaccumulating plants via rhizobacteria can facilitate HM phytoextraction. In the present study, a hyperaccumulator, Sedum alfredii Hance, inoculated with an ABA-catabolizing bacterium Rhodococcus qingshengii, showed higher concentrations of Zn, Cd, Ni, and Pb in the contaminated paddy-grown plant shoots by 35%, 63%, 49%, and 49%, and in plants grown in mine soils by 112%, 105%, 46%, and 49%, respectively, than in the controlbacteria-free plants. However, no significant changes were observed in Cu content between these plants. Furthermore, parameters indicating phytoremediation potential, including the translocation factor (TF) and bioconcentration factor (BCF), revealed that bacterial inoculation could markedly increase the efficacy of Zn, Cd, Ni, and Pb phytoextraction from the soil. Notably, the bioavailabilities of HMs in soils were not influenced by R. qingshengii; however, the expression of transporters related to the uptake of these HMs, including SaIRT1, SaZIP1, SaZIP2, SaZIP3, SaNramp1, SaNramp3, SaNramp6, SaHMA2, and SaHMA3, was upregulated. These findings indicate that R. qingshengii inoculation could increase the HM-uptake ability of plants by catabolizing ABA and may provide a promising strategy for enhancing the phytoremediation efficacy in HM-contaminated soils. [Display omitted] •R. qingshengii enhanced Zn, Cd, Ni, and Pb levels in S. alfredii.•R. qingshengii barely affected Cu accumulation in S. alfredii.•ABA levels of S. alfredii were reduced by R. qingshengii.•R. qingshengii did not affect HM bioavailability in soils.•R. qingshengii upregulated the expression of HM-related uptake transporters.