engleski

Thylakoid system disassembly during bleaching of aurea mutant of maple Acer negundo Hassk. var. Odessanum

Biogenesis of chloroplast photosynthetic membranes is still not a very well understood series of molecular events. Apart from performing reactions of photosynthesis, these specialized biomembranes possess the ability to rearrange itself to adapt to ever-changing light environment. In this work we have used aurea mutant of a free living maple trees to study events, which lead to damage and disassembly of thylakoid membranes during the vegetation season. We have monitored plastid ultrastructural changes, changes in the composition of photosynthetic pigments and proteins, as well as the efficiency of photosystem II. We concluded that strong photoinhibitory processes, coupled with the degradation of proteins, are responsible for the relatively fast reduction of photosynthetic membranes in aurea-type chloroplasts. It is evident that lipid constituents of thylakoid membranes are less susceptible to degradation processes. Once severely damaged, photosynthetic membranes of aurea-type leaves are no longer able to reconstitute intertwined and functionaly intact internal membrane system.

carotenoids ; light harvesting complex ; photoinhibition ; pulse amplitude fluorimetry

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