Reactive oxygen species and nitric oxide affect cell wall metabolism in tobacco BY-2 cells

• Published in: Journal of plant physiology 2004-10, Vol.161 (10), p.1143-1156
• Main Authors: Pacoda, Daniela, Montefusco, Anna, Piro, Gabriella, Dalessandro, Giuseppe
• Format: Article
• Language: English
• Subjects: biochemical pathways; Biological and medical sciences; carbon dioxide; Cell biochemistry; Cell physiology; Cell wall; Cell Wall - metabolism; cell wall components; cell walls; cellulose; cultured cells; Fundamental and applied biological sciences. Psychology; galactose; glucose; Glucose - metabolism; glucose oxidase; Glucose Oxidase - metabolism; glycosyltransferases; hemicellulose; hydrogen peroxide; Hydrogen Peroxide - pharmacology; isotope labeling; Metabolism; Nicotiana - drug effects; Nicotiana - metabolism; Nicotiana tabacum; Nicotiana tabacum L. cv Bright Yellow 2; Nitric oxide; Nitric Oxide - physiology; Nitroprusside - pharmacology; pectins; Plant physiology and development; Polysaccharides; Polysaccharides - metabolism; Reactive oxygen species; Reactive Oxygen Species - metabolism; sodium nitroprusside; tobacco
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1016/j.jplph.2004.01.012

The effects of hydrogen peroxide (H2O2), nitric oxide (NO), and a combination of both on the metabolism of cell wall polysaccharides were studied in tobacco (Nicotiana tabacum L.) cv Bright Yellow 2 (BY-2) suspension cultured cells in the presence of d-[U-14C]glucose or d-[U-14C]galactose as radioactive tracers. We found that the radiolabelling of newly synthesised total cell wall polysaccharides (pectins, hemicelluloses and α-cellulose), buffer-soluble polysaccharides, and membrane-associated polysaccharides decreased under the influence of exogenous systems generating H2O2 and NO. However, when the total amount of newly synthesised cell wall polysaccharides was calculated as a percentage of the total cellular radioactivity (ethanol-soluble pool plus the homogenate of ethanol-insoluble material), all treatments showed negligible effects in the presence of d-[U-14C]glucose or d-[U-14C]galactose as tracers. This occurred because the treatments generating H2O2, NO and H2O2 plus NO caused a marked decrease in the concentration of the ethanol-soluble pool as well as in the total radioactivity found in the homogenate of the ethanol-insoluble material. Most of the radioactivity taken up by the cells was evolved as 14CO2 during the respiratory processes. A qualitative and quantitative characterisation of the ethanol-soluble pool showed that radioactive UDP-sugars in BY-2 suspension cultured cells were differentially reduced by all treatments. Therefore, the decrease of the newly synthesised cell wall polysaccharides seems to be strictly dependent on the reduction of the UDP-sugars pool.