Impact of graphene oxide disturbance on the structure and function of arbuscular mycorrhizal networks

With the widespread application of graphene oxide (GO), its potential toxicity has received increasing attention. The extraradical mycelium of arbuscular mycorrhizal fungi (AMF) can extend from the roots of one plant to those of another, forming complex common mycorrhizal networks (CMNs) for the transfer of nutrients and infochemicals. However, the impact of GO on the structure and transfer function of CMNs remains unknown. In this study, controlled compartments with designated donors and receptors were established to form CMNs after inoculation of Festuca arundinacea plants with Rhizophagus irregularis. GO was found to inhibit host plant growth and decrease AMF colonization, nitrogen and phosphorus uptake, and signal transmission capability in the recipient plants. Specifically, exposure to 5 % GO resulted in decreases of 27.5 % and 35.0 % in shoot and root weights, respectively, and a 38.1 % reduction in AMF colonization. The shoot nitrogen and phosphorus contents were reduced by 41.0 % and 32.3 %, respectively, and the root nitrogen and phosphorus contents were reduced by 12.4 % and 38.6 %, respectively, in response to 5 % GO. Additionally, the upregulation of key genes, such as aquaporin (Rir-AQP2), nitrogen transporter (GiNT), urease (GiURE), and phosphorus transporter (GintPT) in Rhizophagus irregularis was observed in the roots of the recipient plants under the GO treatments, with maximum increases of 192.7 %, 182.6 %, 162.1 %, and 125.8 %, respectively. The differential expressed genes (DEGs) were notably enriched in processes such as the spliceosome and endocytosis, the pentose phosphate pathway, glycolysis and secondary metabolism, and amino acid metabolism. These findings strongly indicate that GO has a significant effect on the structure and functionality of CMNs.