The effect of plant cytokinin hormones on the production of ethylene, nitric oxide, and protein nitrotyrosine in ageing tobacco leaves

• Published in: BioFactors (Oxford) 2006, Vol.27 (1-4), p.203-211
• Main Authors: Wilhelmová, N., Fuksová, H., Srbová, M., Miková, D., Mýtinová, Z., Procházková, D., Vytášek, R., Wilhelm, J.
• Format: Article
• Language: English
• Subjects: Cytokinin; Cytokinins - metabolism; Cytokinins - physiology; ethylene; Ethylenes - biosynthesis; Gene Expression Regulation, Plant; leaf ageing; Nicotiana - genetics; Nicotiana - metabolism; Nicotiana - physiology; nitric oxide; Nitric Oxide - biosynthesis; nitrotyrosine; Plant Growth Regulators - metabolism; Plant Growth Regulators - physiology; Plant Leaves - genetics; Plant Leaves - metabolism; Plant Leaves - physiology; Plants, Genetically Modified; reactive nitrogen species; tobacco; Tyrosine - analogs & derivatives; Tyrosine - biosynthesis
• ISSN: 0951-6433; 1872-8081
• DOI: 10.1002/biof.5520270118

Transgenic plants with genetically increased or decreased levels of cytokinins were used to investigate the effect of cytokinin level on the production of ethylene, a plant hormone with suggested role in senescence, and the production of nitric oxide, potentially important signalling and regulatory molecule. The production of these gases was followed during the course of leaf development and senescence. The production of ethylene and nitric oxide is under genetic control of genes other than those involved in regulation of senescence. The difference in basic ethylene and NO levels in different tobacco cultivars was higher than their changes in senescence. The results of this study did not indicate a direct link between ethylene production and cytokinin levels. However, there was a decreased production of NO in senescent leaves. Low cytokinins level was associated with increased NO production during leaf development. Protein nitrotyrosine proved to be a better indicator of the reactive nitrogen species than measuring of the NO production. Higher nitrotyrosine concentrations were found in insoluble proteins than in the soluble ones, pointing to membrane proteins as the primary targets of the reactive nitrogen species. In plants with elevated cytokinin levels the content of nitrated proteins decreased both in soluble and insoluble fractions. This finding indicates an antioxidative function of cytokinins against reactive nitrogen species.