Root economic spectrum indicates fluoranthene uptake and removal by regulating rhizosphere microflora

Plants exhibit species-specific variations in their ability to uptake and remove polycyclic aromatic hydrocarbons (PAHs), but simple and reliable evaluation metrics remain lacking. The root economic spectrum (RES) reflects the trade-offs plants make in resource acquisition. In this study, eight different plants were selected to investigate whether RES could serve as a potential indicator for PAH uptake and removal, as well as to explore the underlying mechanisms. Fluoranthene (Flu) was selected as the representative PAH. Results revealed that acquisitive and conservative plants, classified according to the RES, exhibited completely different trends in Flu uptake and removal. Acquisitive plants accumulated considerably more Flu (22.59-55.50 μg/pot) than conservative plants (6.38-11.30 μg/pot), attributed to their greater specific root length (SRL), higher root tip numbers and enrichment of functional microorganisms such as Massilia, Olpidium and Erysiphe. Conversely, conservative plants exhibited higher Flu removal rates (95.42 %-96.91 %) than acquisitive plants (82.48 %-93.19 %), due to their higher root tissue density (RTD), larger root diameter (RD) and enrichment of PAH-degrading microorganisms including Nitrosospira, Sporosarcina and Funneliformis. These findings suggest a plant resource-use strategy based on root functional traits that may serve as an indicator for PAH restoration or plant protection.