Abstract
The dark-grown angiosperms cannot convert protochlorophyllide (PChlide) to chlorophyll (Chl) and are etiolated in time. In etiolated chloroplasts and etioplasts, PChlide is localized in prothylakoids (PT) and prolamellar bodies (PLB), giving fluorescence peaks at 633 and 657 nm, respectively. Upon the illumination of etioplasts, PChlide is converted into Chl quickly and assembly of photosystem starts. We performed confocal microspectroscopy at 90 K to stop greening process, to clearly identify PChlide and Chl on different complexes and to study assembly of photosystems during the greening process.
We used a C4 plant Zea mays. C4 plants show different distribution of photosystem I and II between bundle sheath and mesophyll cells. It is interesting how the differentiation of pigment systems in these cells proceeds during greening. We found the ratio of PLB/PT fluorescence to be different between cells near vessel bundle and the outer surrounding cells in etiolated leaves. Two fluorescence bands at about 680 nm and 720 nm emerged after 3 h illumination, and the photosystem I 720 nm fluorescence became higher in cells around vessel bundle, suggesting the differentiation process.
