Metabolomic insights into sulfate-enhanced manganese remediation in Polygonum lapathifolium Linn

Abstract

Our previous studies have demonstrated that sulfate can enhance the accumulation of manganese (Mn) in Polygonum lapathifolium Linn (P. lapathifolium L.). However, the underlying mechanisms, particularly the regulatory mechanisms at the metabolic level, remain unclear. This study systematically investigates the mechanism of sulfate on Mn accumulation in P. lapathifolium L. using metabolomics. We analyzed the plant's growth characteristics, Mn accumulation, photosynthetic pigment content, and metabolite composition after 55 days of cultivation. The results show that Mn treatment increased plant weight and root length, decreased plant height, and increased lateral branches significantly (P < 0.05). Sulfate addition further influenced growth indicators, suggesting a complex role in plant growth regulation. Mn accumulation was highest in leaves, and sulfate addition significantly increased Mn concentrations in all plant parts. Bioconcentration and translocation factor analyses showed improved Mn translocation from roots to above-ground parts with sulfate treatment. PCA and OPLS-DA revealed significant differences in metabolite composition between treatment groups, notably in flavonoids, organooxygen compounds, and carboxylic acids and derivatives. KEGG enrichment analysis indicated significant enrichment of flavonoid biosynthesis, propanoate metabolism, and ABC transporters, suggesting their crucial role in Mn stress response. Mantel Test revealed significant correlations between environmental factors and metabolites, with available potassium (AK), available phosphorus (AP), and soil Mn significantly influencing key metabolite synthesis. These findings enhance the understanding of P. lapathifolium L.‘s metabolic response to Mn stress, showing that sulfate enhances Mn tolerance and remediation by regulating metabolite synthesis and transport, providing a basis for improved phytoremediation techniques.