Multi-omics analysis of the rhizosphere effects and molecular mechanisms of Ageratum conyzoides linn. at different stages of Cd, Pb, and Zn co-stress.

Ageratum conyzoides Linn. is a promising candidate for multi-metal remediation. This study examined the rhizosphere microecology and molecular regulation of A. conyzoides under Cd, Pb, and Zn co-stress after 21 and 50 days of exposure. The ethanol-extracted fraction was found to be the predominant form of Cd, Pb, and Zn in the roots, whereas the NaCl-, HCl-, and HAc-extracted fractions prevailed in the shoots. Heavy metals were mainly distributed in the cell wall and soluble fractions. Metabolome and microbiome analyses revealed dynamic changes in rhizosphere exudate metabolic profiles and bacterial community composition in the rhizosphere soil after 21 and 50 days of exposure to stress. After 21 days of stress, increased exudation of oxalic acid, L-valine, and L-glutamate was correlated with the enrichment of Clostridium_sensu_stricto_12 and norank_p_FCPU426. After 50 days of stress, significantly increased exudation of jasmonic acid, gibberellin A24, and 4-hydroxynonenal was correlated with the enrichment of Bauldia, Candidatus_Udaeobacter, and norank_f_Anaerolineaceae. Transcriptome analysis revealed that prolonged stress upregulated the expression of SEC61A2, Uggt, Ggt7, gss, and PRX1 in A. conyzoides leaves; the differentially expressed genes were found to be significantly enriched in the protein processing in the endoplasmic reticulum pathway and glutathione metabolic pathway. Overall, these findings provide a theoretical foundation for optimizing phytoremediation using A. conyzoides.