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Title: | Increased content of endogenous cytokinins does riot delay degradation of photosynthetic apparatus in tobacco | Authors: | SYNKOVÁ, Helena VAN LOVEN, Karen VALCKE, Roland |
Issue Date: | 1997 | Publisher: | INST EXPERIMENTAL BOTANY, ACAD SCI CZECH REPUBLIC | Source: | PHOTOSYNTHETICA, 33(3-4). p. 595-608 | Abstract: | The effect of stress (long-term darkening) on the structure and functioning of the photosynthetic apparatus was studied in leaves of non-transformed as well as two types of ipt-transformed tobacco (Nicotiana tabacum cv. Petit Havana SR1) plants, The ipt-gene controlling the biosynthesis of cytokinins (CKs) was coupled to the light-inducible Pssu-promoter of Pisum sativum of to the heat-inducible hsp-promoter of Drosophila melanogaster. Pssu-ipt transgenic grafts with high contents of endogenous CKs retained their chlorophyll (Chi) content during a 15 d dark treatment while the SR1- and heat-treated Phsp 70-ipt seedlings, which did not differ significantly in CKs content, lost up to 60 % of their Chi. The normalised variable fluorescence ratio (F-v/F-m) and oxygen evolution decreased dramatically in the course of continuous dark treatment, indicating a degradation of photosystem. 2 irrespective of the plant type. Changes in the polypeptide composition of thylakoid membranes, as analysed by SDS-PAGE, confirmed this degradation process. Light and electron microscopic observations of leaf sections, and of the ultrastructure of plastids showed changes corresponding to a degradation of the photosynthetic apparatus. | Notes: | LIMBURGS UNIV CTR,DEPT SBG,B-3590 DIEPENBEEK,BELGIUM.Synkova, H, ACAD SCI CZECH REPUBL,INST EXPT BOT,KARLOVCE 1A,CZ-16000 PRAGUE 6,CZECH REPUBLIC. | Keywords: | carotenoids; chlorophyll content and fluorescence kinetics; chloroplast ultrastructure; cytokinin; dark stress; ipt-gene; photosynthesis | Document URI: | http://hdl.handle.net/1942/3315 | DOI: | 10.1002/9780470988855.ch13 | ISI #: | A1997YA11100026 | Type: | Journal Contribution |
Appears in Collections: | Research publications |
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