Getting to the roots of N, P, and K uptake.

The soil contributes to the main pool of essential mineral nutrients for plants. These mineral nutrients are critical elements for the building blocks of plant biomolecules, play fundamental roles in cell processes, and act in various enzymatic reactions. The roots are the main entry point for mineral nutrients used within the plant to grow, develop, and produce seeds. In this regard, a suite of plant nutrient transport systems, sensors, and signaling proteins function in acquiring mineral nutrients through the roots. Mineral nutrients from chemical fertilizers, composed mainly of nitrogen, phosphorus, and potassium (NPK), are added to agricultural land to maximize crop yields, worldwide. However, improving nutrient uptake and use within crops is critical for economically and environmentally sustainable agriculture. Therefore, we review the molecular basis for N, P, and K nutrient uptake into the roots. Remarkably, plants are responsive to heterogeneous nutrient distribution and align root growth and nutrient uptake with nutrient-rich patches. We highlight the relationship between nutrient distribution in the growth environment and root system architecture. We discuss the exchange of information between the root and shoot systems through the xylem and phloem, which coordinates nutrient uptake with photosynthesis. The size and structure of the root system, along with the abundance and activity of nutrient transporters, largely determine the nutrient acquisition rate. Lastly, we discuss connections between N, P, and K uptake and signaling.