SIMULTANEOUS MEASUREMENT OF CHANGES IN RED AND BLUE FLUORESCENCE IN ILLUMINATED ISOLATED-CHLOROPLASTS AND LEAF PIECES - THE CONTRIBUTION OFNADPH TO THE BLUE FLUORESCENCE SIGNAL

A newly developed nitrogen laser fluorimeter insensitive to actinic il lumination was used to follow simultaneously the light induced changes in red and blue fluorescence of intact isolated spinach chloroplasts and leaf pieces. The recorded variable blue fluorescence was linked to a water soluble component of intact isolated chloroplasts, depended o n Photosystem I, and was related to changes in carbon metabolism. From the comparison of changes in intact and broken chloroplasts and from fluorescence spectra under different conditions, it was concluded that the variation in NADPH was the major cause for the changes in blue fl uorescence. This study opens a path towards continuous and non-destruc tive monitoring of NADPH redox state in chloroplasts and leaves.