Photoinhibitory printing on leaves, visualised by chlorophyll fluorescenceimaging and confocal microscopy, is due to diminished fluorescence from grana

By analogy with the starch printing technique, it was hypothesised that pho toinhibition could be used to print images on leaves that would be invisibl e to the eye, but easily revealed by chlorophyll fluorescence imaging. We f irst illustrate the process of chlorophyll fluorescence printing on leaves of the shade plant, Cissus rhombifolia, using photographs of artefacts from starch printing experiments in the laboratory of Molisch. We then use port raits of current leaders in chlorophyll fluorescence research to demonstrat e the stability of these images in living tissues. Text printing from micro film of Ewart's pioneering studies in photoinhibition shows the resolution of the method with the fixed-focus, portable, imaging system used here. The stability of images, as well as quenching analysis of images and of leaves , suggests that localised photoinactivation, rather than sustained photopro tection, is responsible for the detail displayed by fluorescence printing. Electron micrograph positives of stained thylakoids can be printed to creat e an illusion of what is imagined to be the source of chlorophyll fluoresce nce at the membrane level. Individual chloroplasts in adjacent cells under the grid pattern of granal stacks printed on leaves were also examined usin g a confocal microscope. Compared with chloroplasts in the shaded parts of the grid, those in the photoinactivated parts of the grid show greatly redu ced chlorophyll autofluorescence. Moreover, these chloroplasts have lost th e localised bright fluorescence from grana. Comparisons of fluorescence yie lds show that relative chlorophyll autofluorescence from grana observed in the confocal microscope parallels that determined in leaves. Our experiment s provide direct visual evidence that fluorescence from grana is lost follo wing photoinactivation of photosystem II in vivo.