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

Nitrate (NO) uptake and distribution are critical to plant life. Although the upstream regulation of NO uptake and downstream responses to NO in a variety of cells have been well studied, it is still not possible to directly visualize the spatial and temporal distribution of NO 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 distribution in . This biosensor tracked the spatiotemporal distribution of NO along the primary root axis and disruptions by genetic mutation of transport (low NO uptake) and assimilation (high NO accumulation). The developed biosensor effectively monitors NO concentrations at the cellular level in real time and spatiotemporal changes during the plant life cycle.