1、Nitrogen assimilation in plants: current status and future prospects

In this review, we summarize the function and regulation of these enzymes reported in three major crops—rice, maize, and wheat, also in the model plant Arabidopsis, and we highlight their application in improving NUE of crops via manipulating N assimilation.

2、intersection of nitrogen nutrition and water use in plants: new paths

In this review, we explore the intricate relationship between water and nitrogen transport in plants, from transpiration-driven mass flow in the soil to uptake by roots via membrane transporters and channels and transport to aerial organs.

3、Root Nitrogen Acquisition and Assimilation

This review covers the molecular mechanisms that the plant uses for accessing these soil N pools and briefly includes consideration of the root N assimilatory pathways that exist in the plant.

4、Nitrogen Journey in Plants: From Uptake to Metabolism, Stress Response

Plants uptake and assimilate nitrogen from the soil in the form of nitrate, ammonium ions, and available amino acids from organic sources. Plant nitrate and ammonium transporters are responsible for nitrate and ammonium translocation from the soil into the roots.

Microbe‐dependent and independent nitrogen and phosphate acquisition

Direct and indirect uptake pathways for plants to obtain nitrogen and phosphorus. The plants directly absorb N and P from the soil through root epidermal cells, called the direct uptake pathway. There are many ways for plants to obtain nutrients indirectly, called the micobe-dependent pathway.

Nitrogen sensing and root development in plants

To adapt to changes in nitrogen availability in the soil, plants employ complex signaling pathways to finely regulate root system architecture to optimize nitrogen uptake efficiency.

Nitrogen Journey in Plants: From Uptake to Metabolism, Stress

Plants uptake and assimilate nitrogen from the soil in the form of nitrate, ammonium ions, and available amino acids from organic sources. Plant nitrate and ammonium transporters are responsible for nitrate and ammonium translocation from the soil into the roots.

Nitrogen acquisition by roots: physiological and developmental

In this review, we aim at detailing recent advances in the identification of molecular mechanisms responsible for physiological and developmental responses of root N acquisition to changes in N availability. These mechanisms are now unravelled at an increasing rate, especially in the model plant Arabidopsis thaliana L..

How Plant Root Exudates Shape the Nitrogen Cycle

Root exudates that specifically inhibit soil nitrification have been identified in important crop species, including rice, wheat, and sorghum, while others have been shown to stimulate root nodulation and N 2 fixation, even in neighboring plants.

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

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.

The process by which plant roots absorb nitrogen fertilizer and nitrogen-containing water is a complex biochemical reaction involving multiple enzymes and transport proteins. Below is a detailed explanation of how plants absorb nitrogen and nitrogen-based solutions:

1. Nitrogen Absorption: Nitrogen is an essential nutrient for plant growth, development, and yield. Plants absorb nitrogen from the soil primarily through nitrate reductase in their roots, which converts soil nitrate (NO₃⁻) into ammonium ions (NH₄⁺).

2. Transport of Ammonium Ions: After absorption, ammonium ions enter the xylem and are transported through the xylem’s vascular system to various parts of the plant. During this process, ammonium ions are further converted into ammonia (NH₃), the directly usable form of nitrogen for plants.

3. Utilization of Ammonia: Inside the plant, ammonia is transformed into amino acids, which serve as raw materials for protein synthesis and participate in various life activities. Ammonia can also act as an energy source, releasing energy through respiration.

4. Use of Nitrogen Fertilizers: In agriculture, chemical fertilizers are applied to supplement soil nitrogen, improving crop yields. Nitrogen in fertilizers mainly exists in ammonium form, which is easily absorbed by plants. When fertilizers are added to soil, their nitrogen reacts with organic matter to produce ammonium ions for plant uptake.

5. Application of Nitrogen-Containing Water: Nitrogen-containing water refers to aqueous solutions with a certain nitrogen concentration, often used for irrigation. After application, nitrogen in the water reacts with soil organic matter to form ammonium ions, which are absorbed by plants. Additionally, nitrifying bacteria may convert this nitrogen into nitrates for plant absorption.

6. Plant Nitrogen Requirements: A plant’s nitrogen needs depend on factors like species, growth stage, and climate. Gramineous plants typically require more nitrogen, while legumes prioritize phosphorus. Nitrogen demands also vary by growth phase: seedlings need less nitrogen, while flowering and fruiting stages require more.

7. Nitrogen Fixation: Under certain conditions, plants can reduce atmospheric nitrogen gas (N₂) into ammonia through nitrogen fixation, reducing reliance on external nitrogen sources. This process is common in legumes, which convert atmospheric nitrogen into usable ammonium ions.

8. Nitrogen Cycling: Nitrogen in plants circulates within ecosystems. Some nitrogen returns to the soil through decaying plant residues, nourishing future crops. Animals (e.g., insects, birds) also introduce nitrogen into ecosystems by consuming plants or other animals, helping maintain ecological nitrogen balance.

plants absorb soil nitrogen through roots, convert it into ammonium ions, and transport it via the xylem. Ammonia is used for amino acid synthesis, energy release, or converted into nitrates for other organisms. In agriculture, fertilizers and nitrogen-containing water effectively supplement soil nitrogen, promoting crop growth.