Abstract
It has been well known that photosystem II and photosystem I are concentrated in the stacked and unstacked part of thylakoid membranes, respectively, in the case of plant chloroplasts. Since color-selected fluorescence microscopic images of chloroplasts may partially differentiate distribution of PSI from that of PSII due to their different colors, we have made efforts to characterize fluorescence spectra in the case of near infrared laser excitation. We have found that fluorescence microscopy based on a near infrared laser in the continuous wave mode can show chloroplast images in Zea mays with a high contribution from photosystem I even in mesophyll chloroplasts, which was explained by a one-photon excitation mechanism. The same setup applied to the identical chloroplasts in the case of femtosecond pulsed oscillation mode at the same laser wavelength generated images rich in photosystem II fluorescence. We have obtained highly pure fluorescence spectra of photosystem I and II, and used them for preparing photosystem selective images in the intrachloroplast space.
