Changes of Time Courses of Delayed Fluorescence and Prompt Fluorescence during in vivo and in vitro Photoactivation of the Oxygen-evolving System in Dark-grown Spruce Seedlings

Abstract

Photoactivation of the oxygen-evolving system in intact leaves and in isolated chloroplasts of dark-grown spruce (Picea abies) seedlings was studied by measuring the transient time courses of the delayed and prompt fluorescence of chlorophyll. The delayed fluorescence (measured between 0.5 and 12.5 msec after 15 msec illumination) as well as the prompt fluorescence of intact leaves increased in intensity when the oxygen-evolving system was activated by a short period of illumination. After illumination of chloroplasts isolated from the dark-grown seedlings, the long-lived component of delayed fluorescence (> 100 msec) was enhanced, but not that in the millisecond time range. An analysis of the ionic dependencies of the intensities of prompt and delayed fluorescence showed that the thylakoid membranes of chloroplasts isolated from dark-grown seedlings had almost the same electrostatic properties as those of mature angiosperm chloroplast membranes.