Detection of the effects of exogenous signal molecules on ATP levels in Arabidopsis thaliana(L.)Heynh. using fluorescence resonance energy transfer

We used an adenosine triphosphate (ATP) fluorescence protein-sensor (Ateam1.03-nD/nA) based on fluorescence resonance energy transfer (FRET) to analyze the effects of extracellular ATP, Ca²⁺, H₂O₂, and NO on ATP levels in the cytoplasm and chloroplasts of Arabidopsis thaliana seedlings. Results showed that ATP levels were higher in the cytoplasm than in the chloroplasts. Under treatment with different concentrations of the signal molecules, the FRET ratio of plastid-localized Ateam 1.03-nD/nA fluctuated non-significantly between 1.2 and 1.8. The FRET ratio of cytosol-localized Ateam1.03-nD/nA fluctuated non-significantly between 2.2 and 3.0. These results indicate that both cytoplasmic ATP and chloroplast ATP maintained relatively stable levels upon stimulation by signal molecules at different intensities.