ZmNPF7.10 confers potassium and nitrogen distribution from node to leaf in maize.

In graminaceous plants, nodes play vital roles in nutrient allocation, especially for preferential nutrient distribution to developing leaves and reproductive organs. However, the molecular mechanisms underlying this distribution remain poorly understood. In this study, we identified a transporter named ZmNPF7.10 that is involved in potassium (K) and nitrogen (N) distribution in maize nodes. In Xenopus oocytes, ZmNPF7.10 showed NO and K transport activity in a pH-dependent manner. ZmNPF7.10 is predominantly expressed in the nodes at the reproductive growth stage, and preferentially expressed in the xylem parenchyma cells of enlarged vascular bundles (EVBs) in nodes. Disruption of ZmNPF7.10 resulted in the decline of K and N in leaves, but accumulation of K and N in nodes, suggesting ZmNPF7.10 conducts K and N distribution from nodes to leaves in maize. We identified a natural variant of 7.1-kb InDel in the promoter region that was significantly associated with ZmNPF7.10 transcript level in nodes, leaf K and N concentration, as well as grain yield. These findings demonstrate that ZmNPF7.10 functions as a dual role transporter that mediates K and N distribution in nodes. This study provides important insights into the molecular mechanisms of nutrient distribution in maize.