biologia plantarum

Biologia plantarum 50:31-41, 2006 | DOI: 10.1007/s10535-005-0071-0

Cytokinin-induced activity of antioxidant enzymes in transgenic Pssu-ipt tobacco during plant ontogeny

H. Synková^1,*, Š. Semorádová^1,2, R. Schnablová^1,2, E. Witters³, M. Hušák⁴, R. Valcke⁵

¹ Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Praha, Czech Republic

² Faculty of Sciences, Charles University, Praha 2, Czech Republic

³ Department of Biology, University of Antwerpen, Wilrijk-Antwerpen, Belgium

⁴ University of South Bohemia, Ceske Budejovice, Czech Republic

⁵ Department of SBG, Limburgs Universitair Centrum, Universitaire Campus, Diepenbeek, Belgium

Cytokinin (CK) content and activities of several antioxidant enzymes were examined during plant ontogeny with the aim to elucidate their role in delayed senescence of transgenic Pssu-ipt tobacco. Control Nicotiana tabacum L. (cv. Petit Havana SR1) and transgenic tobacco with the ipt gene under the control of the promoter of small subunit of Rubisco (Pssu-ipt) were both grown either as grafts on control rootstocks or as rooted plants. Both control plant types showed a decline in total content of CKs with proceeding plant senescence. Contrary to this both transgenic plant types exhibited at least ten times higher content of CKs than controls and a significant increase of CK contents throughout the ontogeny with maximal values in the later stages of plant development. Significantly higher portion of O-glucosides was found in both transgenic plant types compared to control ones. In transgenic plants, zeatin and zeatin riboside were predominant type of CKs. Generally, Pssu-ipt tobacco exhibited elevated activities of antioxidant enzymes compared to control tobacco particularly in the later stages of plant development. While in control tobacco activity of glutathione reductase (GR) and superoxide dismutase (SOD) showed increasing activity up to the onset of flowering and then gradually decreased, in both transgenic types GR increased and SOD activity showed only small change throughout the plant ontogeny. Ascorbate peroxidase (APOD) was stimulated in both transgenic types. The manifold enhancement of syringaldazine and guaiacol peroxidase activities was observed in transgenic grafts throughout plant ontogeny in contrast to control and transgenic rooted plants, where the increase was found only in the late stages. Electron microscopic examination showed higher number of crystallic cores in peroxisomes and abnormal interactions among organelles in transgenic tobacco in comparison with control plant. The overproduction of cytokinins resulted in the stimulation of activities of AOE throughout the plant ontogeny of transgenic Pssu-ipt tobacco.

Keywords: ascorbate peroxidase; catalase; glutathione reductase; guaiacol peroxidases; superoxide dismutase; syringaldazine peroxidase

Subjects: antioxidants, antioxidative enzymes; ascorbate peroxidase; catalase; chloroplast; cytokinins; dithiothreitol; β-glucuronidase; glutathione reductase; guaiacol peroxidase; leaf ultrastructure; mitochondrion; Nicotiana tabacum; ontogeny, plant; peroxisome; ribulose-1,5-bisphosphate carboxylase/oxygenase; root, rooting; starch; superoxide dismutase (SOD); syringaldazine peroxidase; transgenic plants (cf. also in vitro…)

Received: September 14, 2004; Accepted: June 9, 2005; Published: March 1, 2006  Show citation