Utilization strategies of inorganic nitrogen in submerged macrophytes

As important components in aquatic ecosystems, submerged macrophytes can alleviate nitrogen load and improve the healthy operation of ecosystems through direct and indirect ways. Nitrogen utilization strategies of submerged macrophytes differ significantly from those of terrestrial plants. Submerged macrophytes can uptake nitrogen not only from the overlying water, but also from pore water in sediments via above-ground and below-ground parts, respectively. To adapt to the various changes in nitrogen content in aquatic environments, submerged macrophytes exhibit two directions of nitrogen translocation, namely acropetal and basipetal translocation. To avoid the toxicity caused by high nitrogen concentrations, a trade-off exists in nitrogen utilization between the above- and below-ground parts of submerged macrophytes. The GS/GOGAT cycle and GDH pathway are the primary pathways for nitrogen assimilation in submerged macrophytes. Currently, research on submerged macrophytes lags far behind that on terrestrial plants. Further exploration of the mechanisms underlying nitrogen utilization in submerged macrophytes is still needed and a suitable genetic transformation system of submerged macrophytes is required. Molecular technologies such as gene editing can be used to identify gene function, which should promote further studies on the structure and function of key proteins.