Effect of abiotic stresses on the activity of antioxidative enzymes and contents of phytohormones in wild type and AtCKX2 transgenic tobacco plants

Mýtinová Z.*, Motyka V.*, Haisel D., Gaudinová A., Lubovská Z., Wilhelmová N. (*contributed equally)
BIOLOGIA PLANTARUM 54: 461-470, 2010

Keywords: abiotic stress; abscisic acid; antioxidative enzymes; cytokinin; cytokinin oxidase/dehydrogenase; drought; salinity; zinc
Abstract: The responses of antioxidant enzymes (AOE) ascorbate peroxidase (APX), glutathione reductase (GR), superoxide dismutase (SOD), and catalase (CAT) in soluble protein extracts from leaves and roots of tobacco (Nicotiana tabacum L. cv. Samsun NN) plants to the drought stress, salinity and enhanced zinc concentration were investigated. The studied tobacco included wild-type (WT) and transgenic plants harbouring the cytokinin oxidase/dehydrogenase (CKX) gene under control of 35S promoter from Arabidopsis thaliana (AtCKX2). The transgenic plants exhibited highly enhanced CKX activity and decreased contents of cytokinins and abscisic acid in both leaves and roots, altered phenotype, retarded growth, and postponed senescence onset. Moreover, an enhanced photoprotection was found in leaves of AtCKX2 tobacco previously. Under control conditions, the AtCKX2 plants exhibited noticeably higher activity of GR in leaves and APX and SOD in roots. The AOE responses to the stresses differed between AtCKX2 and WT plants as well as between leaves and roots within individual plants. The stress conditions induced the opposite effects on CAT activity in leaves: it always decreased upon stresses in WT while increased in AtCKX2 plants. On the contrary, the SOD activity enhanced in WT but declined in AtCKX2 leaves. In roots, the APX activity prevailingly increased in WT while mainly decreased in AtCKX2 in response to the stresses. Both WT and AtCKX2 leaves as well as roots exhibited elevated abscisic acid concentration and increased CKX activity under all stress conditions while endogenous CKs and IAA levels were not much affected by stress treatments in either WT or transgenic plants.
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IEB authors: Alena Gaudinová, Daniel Haisel, Václav Motyka, Naďa Wilhelmová