Surface Charge Densities and Membrane Fluidities in Thylakoids with Different Degrees of Thylakoid Appression After Norflurazon Treatment

Autor: Clas Dahlin
Rok vydání: 2003
Předmět:
Zdroj: Photosynthetica. 41:635-639
ISSN: 1573-9058
0300-3604
DOI: 10.1023/b:phot.0000027532.55335.a7
Popis: Wheat seedlings (Triticum aestivum L.) develop plastids (etioplasts and chloroplasts) which exhibit alterations in inner membrane organisation after treatment with Norflurazon (NF), an inhibitor of carotenoid biosynthesis. In dark-grown plants, results in a decreased amount of partitions (contact zones) between prothylakoids. In weak red light, the results in plants containing chloroplasts devoid of grana. Assays have been performed to investigate the membrane surface charge density in these membranes, and relate possible differences to the absence of (pro-)thylakoid overlap after NF teatment. Using the fluorescent probe 9- amino acridine (9-AA), the average surface charge density of isolated PTs was -21.8±3.2 mC m-2 and - 27.4±2.6 mC m-2 in the control and after, respectively. Thylakoid membranes isolated from plants grown in weak red light exhibited slightly more negative values, -23.5±2.9 mC m-2 and -29.0±2.1 mC m-2, in control and after, respectively. The surface charge density of destacked thylakoids from greenhouse-grown untreated plants, containing extensive grana stacking, was -34.3±2.5 mC m-2. Assays using the fluorescent probe of DPH (1,6- diphenyl- 1,3,5- hexatriene) showed that this probe exhibits a higher polarisation value when incorporated into thylakoids from NF- treated plants compared to untreated plants grown in weak red light. The highest polarisation value was found in untreated plants grown in the greenhouse. This indicates a lower rotation transition of the probe in the lipid environment of thylakoids after NF treatment, which can be interpreted as more rigid membranes. These results suggest that the surface charge density and the mobility of membrane components may play a major role for the formation of partitions in dark-grown plants and in the formation of grana in plants grown in weak red light. 23 Additional key words: chloroplasts; etioplasts; (pro-)thylakoids; Triticum; stacking; wheat; 9- amino acridine.
Databáze: OpenAIRE
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