Native and atrazine-induced fluorescence of chloroplasts from palisade and spongy parenchyma of beech ( Fagus Sylvatica l.) leaves

Abstract

Native and atrazine-induced fluorescence of chloroplasts from palisade and spongy parenchyma of european beech ( Fagus sylvatica L.) leaves are investigated by high-resolution laser-scanning microscopic imaging and 3D-image processing software. The effects of light as environmental factor for leaf morphology (sunny and shade leaves) and atrazine as a D-protein receptor blocker of the chloroplast-thylakoid antenna protein complex on chlorophyll fluorescence are studied by successive z-scans (depth scan). Significant differences in chlorophyll fluorescence intensities of sunny and shade leaves are observed. The diffuse and nondiffuse chlorophyll fluorescence of sunny leaf are higher than those of the shade leaf at each z-depth. Strong fluorescence of grana stacks from palisade parenchyma chloroplast due to atrazine treatment indicates a high number of DI protein binding sites at the grana stacks of palisade parenchyma chloroplast at each z-depth. It seems that a shutterlike arrangement of Dl-D2-Cytochrome b559-CP43-CP47 complexes exists, and apparently it regulates the light absorption, photosynthetic quantum conversion, and the fluorescence and protects the PSII antenna structures from thermal disturbances. As compared to chlorophyll fluorescence at atrazine bound sites, the generation of native chlorophyll fluorescence is suggested to take place at other than D1-associated chlorophyll protein complexes.