Enhanced inducibility of glutathione S-transferase activity by paraquat in poplar leaf discs in the presence of sucrose

Gullner, Gábor and Gyulai, Gábor and Bittsánszky, András and Kiss, J. and Heszky, László and Kőmíves, Tamás (2005) Enhanced inducibility of glutathione S-transferase activity by paraquat in poplar leaf discs in the presence of sucrose. PHYTON-ANNALES REI BOTANICAE, 45 (3). pp. 39-44. ISSN 0079-2047

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Abstract

Leaf discs of the wildtype poplar hybrid Populus canescens and its two transgenic lines overexpressing gamma-glutamylcysteine synthetase in the cytosol or in the chloroplasts were exposed to the herbicide paraquat (4 x 10(-9) to 4 x 10(-6) M). Leaf discs were incubated on tissue culture media containing 0.2, 1.0 or 2.0% sucrose. Exposure to paraquat led to a concentration-dependent decrease of GST activities at 0.2% sucrose. However, at higher external sucrose supplies, paraquat brought about marked inductions of GST activities in all poplar lines. The GST induction was light-dependent. Fluorescence measurements showed that the efficiency of the photosynthetic apparatus was inhibited by high paraquat concentrations (4 x 10(-7) - 4 x 10(-6) M) in all poplar clones. The photosynthetic efficiency (F-v/F-m) decreased also in leaf discs incubated in continuous darkness in the presence of paraquat.

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