Multi-Omics Analysis Reveals the Mechanism by Which RpACBP3 Overexpression Contributes to the Response of Robinia pseudoacacia to Pb Stress

Acyl-CoA-binding protein (<i>ACBP</i>) genes have been implicated in lead enrichment and translocation in plants; however, the mechanisms by which these genes contribute to the response to heavy metal stress in various taxa have not been determined. In this study, the molecular mechanisms underlying the response of <i>Robinia pseudoacacia</i>, an economically important deciduous tree, to Pb stress were examined using transcriptomic and metabolomic analyses. <i>RpACBP3</i> overexpression increased Pb enrichment, translocation, and tolerance. After Pb stress for 3 days, 1125 differentially expressed genes (DEGs) and 485 differentially accumulated metabolites (DAMs) were identified between wild-type and <i>RpACBP3</i>-overexpressing <i>R. pseudoacacia</i> strains; after Pb stress for 45 days, 1746 DEGs and 341 DAMs were identified. Joint omics analyses showed that the DEGs and DAMs were co-enriched in α-linoleic acid metabolism and flavonoid biosynthesis pathways. In particular, DEGs and DAMs involved in α-linoleic acid metabolism and flavonoid biosynthesis were up- and down-regulated, respectively. Moreover, <i>RpACBP3</i> overexpression enhanced the ability to scavenge reactive oxygen species and repair cell membranes under stress by regulating <i>LOX</i> gene expression and increasing the phosphatidylcholine content, thereby improving the tolerance to Pb stress. These findings lay a theoretical foundation for the future application of <i>RpACBP3 genes</i> in plant germplasm resource creation and phytoremediation of Pb contaminated soil in which <i>R. pseudoacacia</i> grow.