Reactive oxygen species and nitric oxide affect cell wall metabolism in tobacco BY-2 cells.
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 alpha-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.
Pacoda
Daniela
D
Dipartimento di Scienze e Tecnologie Biologiche e Ambientali, Università di Lecce, via prov. le Lecce-Monteroni, I-73100 Lecce, Italy.
Montefusco
Anna
A
Piro
Gabriella
G
Dalessandro
Giuseppe
G
D002473:Cell Wall / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D005949:Glucose Oxidase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology; D011134:Polysaccharides / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D014026:Nicotiana / Q000187:drug effects* / Q000378:metabolism*
D011134:Polysaccharides; D017382:Reactive Oxygen Species; D009599:Nitroprusside; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D005949:Glucose Oxidase; D005947:Glucose