Visualizing Redox State in Plastids Using a New Biosensor

Plant metabolism consists of highly versatile reactions that must be finely regulated in real-time to ensure cellular coordination throughout the organism’s development. The regulation of these reactions involves adjusting redox activities within different cell compartments, particularly plastids, which house the entire photosynthetic chain for energy molecules. Until now, the most common method for visualizing these regulations involved cell destruction, which did not allow for a full understanding of the dynamics of these reactions over time.

To address this problem, Boon Lim’s team (University of Hong Kong), in collaboration with the team led by Marie-Edith Chabouté and Alexandre Berr, turned to fluorescent biosensors. They developed three new stable sensors (called iNAP1, iNAP4, and SoNar) genetically encoded in the model plant Arabidopsis. Using a dual green and red fluorescence system, these sensors measure the amounts of molecules involved in metabolic reactions, such as NADH, NAD+, and NADPH, in the plastids and cytosol of the cell. The measurements, which demonstrated the system’s effectiveness in visualizing the dynamics of these metabolic compounds in real-time over a few seconds, were mainly conducted in cells of plants with apical growth (such as the pollen tube and root hair) for better visualization with a confocal microscope.

The authors are confident that these new biosensors will allow for more detailed studies of plant metabolism dynamics, whether in response to various treatments or environmental stresses. The study, supported by the General Research Fund of Hong Kong, the National Natural Science Foundation of China, the National Centre for Scientific Research (CNRS), as well as the Human Frontier and the National Research Agency (ANR MecaNuc) programs, was published in The Plant Journal on May 18, 2024.