Metabolomic and systems biology insights into lead stress tolerance of Pennisetum purpureum bioaugmented with Enterobacter cloacae.

Lead (Pb) contamination severely affects plant growth and ecosystem health. The present study integrates systems biology and metabolomics to elucidate Pb stress tolerance mechanisms in Pennisetum purpureum bioaugmented with Enterobacter cloacae. Network based metabolite-gene mapping identified 31 plant metabolites and 65 microbial metabolites associated with Pb uptake and oxidative stress mitigation. Key compounds such as ascorbic acid, glutamine, enterochelin, and methionine were linked to target genes APX1, GLU1, entF, and metG, highlighting antioxidant and metal chelation roles. Pathway enrichment revealed activation of ascorbate, glutathione, methionine, and siderophore biosynthetic routes. Pot culture experiments confirmed enhanced plant growth and Pb tolerance in bioaugmented systems supplemented with 100 µg L⁻¹ of ascorbic acid and glutamine. Gas chromatography-mass spectrometry (GC-MS) profiling of root exudates validated these findings, detecting unique metabolites such as thiophene-3-ol and benzeneethanamine associated with improved plant vigour. These results provide a mechanistic framework for exploiting multi-biosystem metabolomics in phytoremediation and the design of effective plant-microbe strategies for Pb bioremoval.