Protection of winter rape photosystem 2 by 24-epibrassinolide under cadmium stress
Janeczko, A.(Polish Academy of Sciences, Krakow (Poland). Inst. of Plant Physiology)E-mail:[email protected] | Koscielniak, J.(Agricultural Univ., Krakow (Poland). Dept of Plant Physiology) | Pilipowicz, M.(Polish Academy of Sciences, Krakow (Poland). Inst. of Plant Physiology) | Szarek-Lukaszewska, G.(Polish Academy of Sciences, Krakow (Poland). W. Szafer Inst. of Botany) | Skoczowski, A.(Polish Academy of Sciences, Krakow (Poland). Inst. of Plant Physiology)
Seedlings of winter rape were cultured in vitro on media containing 24-epibrassinolide (EBR) and Cd. Cd was strongly accumulated, the presence of EBR reduced its content in cotyledons. Cd lowered the specific energy fluxes per excited cross section (CS) of cotyledon. The number of active reaction centres of photosystem 2 decreased by about 21%, the transport of photosynthetic electrons (ET/CS) by about 17.1%, the activity of O2 evolving centres (OEC) diminished by about 19.5% and energy dissipation (DI/CS) increased by about 14.6%. EBR induced only a small increase in the activity of most photochemical reactions per CS. However, it strongly affected seedlings cultured with Cd. Specific energy fluxes and ET/CS were by 10.9 and 20.9% higher, respectively, than the values in plants cultured with Cd. EBR also limited the increase of DI/CS and simultaneously protected the complex of OEC. EBR reduces the toxic effect of Cd on photochemical processes.
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