In vivo visualization of nitrate dynamics using a genetically encoded fluorescent biosensor

Nitrate (NO(3)(−)) uptake and distribution are critical to plant life. Although the upstream regulation of NO(3)(−) uptake and downstream responses to NO(3)(−) in a variety of cells have been well studied, it is still not possible to directly visualize the spatial and temporal distribution of NO(3)(−) with high resolution at the cellular level. Here, we report a nuclear-localized, genetically encoded fluorescent biosensor, which we named NitraMeter3.0, for the quantitative visualization of NO(3)(−) distribution in Arabidopsis thaliana. This biosensor tracked the spatiotemporal distribution of NO(3)(−) along the primary root axis and disruptions by genetic mutation of transport (low NO(3)(−) uptake) and assimilation (high NO(3)(−) accumulation). The developed biosensor effectively monitors NO(3)(−) concentrations at the cellular level in real time and spatiotemporal changes during the plant life cycle.