Metabolomics reveals the potential mechanism of La(III) promoting enrichment of Sodium hydrogen arsenate and Roxarsone in Solanum nigrum L.

The rare earth element lanthanum (La(III)) has been found to effectively enhance crop yields and improve plant growth and development. Arsenic (As), as a class of toxic metals widely found in the environment, poses a serious threat to both ecological and human health. Research on the application of La(III) in phytoremediation to enhance remediation efficiency is currently lacking. This study examined the impact of La(III) on physiological and biochemical indicators of Solanum nigrum L. (S. nigrum) exposed to Sodium hydrogen arsenate (SA) and Roxarsone (ROX) treatments under hydroponic conditions. Results indicated that La(III) treatment increased S. nigrum's aboveground As transport capacity by 58.68 %-213 % compared to no La(III) application. Additionally, foliar spraying of La(III) significantly inhibited the expression of toxic metabolites in the root system of S. nigrum, reducing Benzamide by 99.79 % under SA treatment and ZON by 87.72 % under ROX treatment. La(III) is likely to promote the transport of toxins and nutrients within and out of cells by activating ABC transporters, thereby enhancing S. nigrum's arsenic tolerance and metabolic activity. These findings provide molecular-scale insights into La(III) enhancement of the resilience of hyper-enriched plants and the remediation potential of contaminated sites.