Reactive oxygen species-induced release of intracellular ascorbate in plant cell-suspension cultures and evidence for pulsing of net release rate
Article first published online: 10 MAY 2010
© The Authors (2010). Journal compilation © New Phytologist Trust (2010)
Volume 187, Issue 2, pages 332–342, July 2010
How to Cite
Parsons, H. T. and Fry, S. C. (2010), Reactive oxygen species-induced release of intracellular ascorbate in plant cell-suspension cultures and evidence for pulsing of net release rate. New Phytologist, 187: 332–342. doi: 10.1111/j.1469-8137.2010.03282.x
- Issue published online: 24 JUN 2010
- Article first published online: 10 MAY 2010
- Received: 22 January 2010, Accepted: 22 March 2010
- cell-suspension cultures;
- hydrogen peroxide (H2O2);
- oxidative stress;
- pulsing of secretion;
- reactive oxygen species (ROS)
- •Apoplastic ascorbate has been proposed to confer resistance to oxidative stresses, e.g. ozone. We investigated reactive oxygen species (ROS)-induced secretion and catabolism of ascorbate.
- •Late-growth-phase cultured cells of rose and Arabidopsis were preloaded with [14C]ascorbate. Radiolabelled metabolites and secretion products were analysed by high-voltage electrophoresis.
- •In both species, exogenous 1 mM hydrogen peroxide (H2O2) rapidly stimulated [14C]ascorbate and [14C]dehydroascorbate accumulation in the medium (apoplast). Net 14C export was most rapid within 100 s of washing, and often showed superimposed pulses, of c. 10-s duration, whose amplitude was greater after H2O2 treatment. Oxidative stress did not cause indiscriminate metabolite leakage from the cells. H2O2 caused c. 20–40% of the intracellular [14C]ascorbate to be irreversibly catabolized to [14C]oxalyl-threonate and related products; however, the great majority of the extracellular radioactivity remained as [14C]ascorbate and [14C]dehydroascorbate. Much of the apoplastic dehydroascorbate was probably reabsorbed by the cells and reduced back to ascorbate.
- •The data show that exported ascorbate can serve an apoplastic antioxidant role in these late-growth-phase cells without being irreversibly lost, whereas in early-growth-phase cells most extracellular ascorbate is irreversibly degraded. In conclusion, cultured plant cells can respond actively to oxidative stress by reversibly exporting ascorbate into the apoplast.