Rising to the Challenge: Developing Biosensors to Study Nitrogen Transport in Plants

Abstract

Nitrogen (N) plays a crucial role in plant development and growth, which is why high concentrations of N in the form of fertilizers are commonly used in agricultural crops. However, the excess N present in fertilizers is predominantly leached into groundwater, resulting in contamination of one of the largest sources of drinking water and posing a significant threat to the environment and public health. It is therefore essential to comprehend the assimilation, transport, and biosynthesis of nitrogen compounds, in order to improve plant growth and development. Unfortunately, many of the biological and metabolic processes that occur at the cellular and subcellular levels in different organs, tissues, cells, and compartments in plants remain unknow due to the lack of tools available for real-time monitoring.

The assimilation of inorganic and organic nitrogen is a complex process that involves numerous transporter systems present in plant cell membranes. These low/high affinity and low/high capacity transporters have been studied in different experimental plant models, but it is still unknown how they are distributed throughout the plant, as well as their modus operandi in each cellular type or intracellular compartment.

In this study, we suggest creating and utilizing dual ratiometric biosensors equipped with fluorescent proteins in various subcellular compartments. Our proposal is based on previous findings on glutamate sensors in plants, which were tested in diverse cellular compartments (Castro-Rodriguez et al., 2021). To generate these biosensors, we identified promising candidates such as the ammonium transporter PpAMT1.3 (Castro-Rodriguez et al., 2016) and the amino acid permease PpAAP1 from a conifer plant model, Pinus pinaster (Llebres et al., 2022).