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Electron Transport Activities of Isolated Thylakoids from Wheat Plants Grown in Salicylic Acid
Author(s) -
Sahu G. K.,
Kar M.,
Sabat S. C.
Publication year - 2002
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1055/s-2002-32336
Subject(s) - thylakoid , electron transport chain , photosystem i , photosynthesis , biology , photosystem , photosystem ii , chloroplast , cytochrome b6f complex , biophysics , biochemistry , gene
Wheat ( Triticum aestivum cv. Sonalika) plants were grown with three different concentrations of salicylic acid (SA; 50/500/1000 μM) for 7 days and the effects on the level of thylakoid photochemical activities were examined. SA treatment stimulated photosystem II‐catalyzed electron flow in all concentrations tested. Photosystem I‐associated electron transport activity was stimulated at low concentrations of SA (50 μM) but at higher concentrations (500 and 1000 μM) the electron transport activity was drastically attenuated. Thylakoids isolated from the leaves of seedlings grown with high concentrations of SA (500 and 1000 μM) showed a substantial reduction in uncoupler (NH 4 Cl)‐mediated stimulation in electron flow. In addition, they failed to support ADP‐dependent stimulation of electron transport activity and induced a significant reduction in ATPase activity. Incubation of isolated thylakoids with SA, however, had no effect on thylakoid photofunction, indicating no direct effect of SA on photoelectron transport activity. Furthermore, high concentrations of SA specifically reduce the thylakoid cytochrome f 554 level. The results suggest that SA, depending on its concentration, imparts differential effects on the photofunction of thylakoids. A low concentration of SA favours photosynthetic activity while the high concentration induces drastic attenuation of photosynthetic activity because of the decline in cytochrome f 554 .