Heterologous expression of water lily nitrate transporter gene NcNPF6.3-1 enhances nitrogen and phosphorus accumulation in plants and promotes nutrient removal from eutrophic water.

Abstract

Main conclusion: Heterologous expression of NcNPF6.3-1 promotes nitrogen and phosphorus accumulation in plants and improves nutrient removal efficiency in eutrophic water, indicating that this gene plays an important role in nutrient acquisition and has potential for phytoremediation applications. Nitrogen (N) and phosphorus (P) are essential mineral nutrients for plant growth. However, their excessive application can lead to water eutrophication. Aquatic plants provide an environmentally friendly and sustainable strategy for the ecological restoration of eutrophic aquatic ecosystems. Water lily (Nymphaea L.) is known to purify eutrophic water, yet the molecular mechanisms underlying its nutrient uptake remain unclear. In this study, we identified and characterized NcNRT1/PTR6.3-1 (NcNPF6.3-1), a nitrate transporter family member from Nymphaea colorata Peter, which is exclusively localized to the plasma membrane. Heterologous expression of NcNPF6.3-1 (NcNPF6.3-1-Ex) in rice (Oryza sativa L.) significantly promoted flowering and increased grain yield under moderate-N (N1: 0.27 g N/kg soil) and low-N (N2: 0.09 g N/kg soil) levels. Furthermore, NcNPF6.3-1-Ex lines exhibited enhanced total N and total P accumulation under N2 conditions. Notably, in simulated eutrophic water, NcNPF6.3-1-Ex lines showed substantially higher removal efficiencies of nitrate nitrogen (NO₃^--N), ammonium nitrogen (NH₄⁺-N), and total P compared with the wild type. These results demonstrate that NcNPF6.3-1 enhances plant nutrient absorption and accumulation while effectively reducing nutrient concentrations in eutrophic water, highlighting its potential application in phytoremediation and ecological restoration of nutrient-polluted aquatic ecosystems.