Fluorescence Emission Spectra of Etiolated Leaves Measured at 296 and 77 K during the First Seconds of Continuous Illumination

Abstract

In the literature it is already well established that the illumination of an etiolated leaf results in the photoreduction of protochlorophyll(ide) P_{657 – 650} ^* to two forms of chlorophyll(ide) P_{676 – 668} (present in minor amounts) and P_{688 – 676} (6, 7, 12). The latter is subsequently transformed into P_{695 – 682} (4, 10, 11) which then undergoes the Shibata shift (8) to P_{680 – 672}. These maximum shifts have already been described also for etiolated Raphanus cotyledons (3) after illumination with one flash. During continuous illumination at room temperature the fluorescence intensity of an etiolated leaf shows a fast rise and a subsequent slow decline (1, 2, 6). This decline was explained by a continuously decreasing fluorescence yield of P_{695 – 682} (6).