9.C.23.  The Plant Substituted Polycyclic Aromatic Hydrocarbon Uptake (sub-PAH-U) Family 

Substituted polycyclic aromatic hydrocarbons (sub-PAHs) are highly toxic and ubiquitous (Yang et al. 2024), but the accumulation of sub-PAHs in crop roots is unclear. In the study by Yang et al. 2024, the accumulation mechanism of sub-PAHs in crop roots was systematically disclosed by hydroponic experiments from the perspectives of utilization, uptake, and elimination. The obtained results showed an interesting phenomenon that despite not having the strongest hydrophobicity among five sub-PAHs, nitro-PAHs (including 9-nitroanthracene and 1-nitropyrene) displayed the strongest accumulation potential in the roots of legume plants, including mung bean and soybean. The nitrogen-deficient experiments, inhibitor experiments, and transcriptomics analysis revealed that nitro-PAHs could be utilized by legumes as a nitrogen source, thus being significantly absorbed by active transport, which relies on amino acid transporters driven by H⁺-ATPase. Molecular docking simulation further demonstrates that the nitro group is a significant determinant of interaction with an amino acid transporter. Moreover, the depuration experiments indicate that the nitro-PAHs may enter the root cells, further slowing their elimination rates and enhancing the accumulation potential in legume roots. These results shed light on a previously unappreciated mechanism for root accumulation of sub-PAHs, which may affect their biogeochemical processes in soils (Yang et al. 2024).

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