Measurement of the pH and Electric Field Developed Across Arabidopsis Thylakoids in the Light

Measurement of the different components of the proton motive force (pmf) gives information about the coupling of proton movement within thylakoids to chemiosmotic processes such as photophosphorylation and protein transport, as well as that relating to the overall quality of a thylakoid preparation. The techniques to assess the pmf have been known for many years, as they have been applied to the most popular model plants for photosynthetic research. The emergence of Arabidopsis thaliana as the prominent model plant in developmental and genetics research prompted us to apply these techniques to thylakoids isolated from Arabidopsis chloroplasts. We describe here two spectroscopic techniques to measure the transmembrane pH gradient and electric field developed in the light in Arabidopsis thylakoids.