Contribution of a plasma membrane redox system to the superoxide production by wheat root cells

Abstract

Summary. Wound stress activated wheat root cells to produce oxygen radicals. The production was accompanied by an increased permeability for potassium ions and a depolarization of the plasma membrane. Various electron donors, such as the nonpenetrating donor potassium ferrocyanide as well as NADH and NADPH, caused the amplification of superoxide production by root cells. The Oa'--generating system in wheat root cells was found to be considerably sensitive to diphenylene iodonium, which is generally considered as a suicide inhibitor of neutrophil NADPH oxidase, and to other inhibitors of flavoprotein activity, chlorpromazine and quinine. The xenobiotic compound amidopyrine caused activation of the 02--generating system, which was depressed by DPI. The O2'--generating system in root ceils was shown to be significantly dependent on calcium content. Calcium loading of the root cells induced a powerful increase of the superoxide release. Data obtained indicate that superoxide generation is one of the early events of the wound stress response. Redox systems of the plasma membrane may be involved in the superoxide production in response to wound stress and detoxification of xenobiotic compounds in root ceils.

NADH-stimulated, cyanide-resistant superoxide production in maize coleoptiles analyzed with a tetrazolium-based assay

“…The O á À 2 -producing activity appears to be localized at the plasma membrane and is particularly abundant in the outer epidermis of the coleoptile. The enzyme responsible for this activity can accept electrons from NADH experimentally supplied to the apoplastic side of the plasma membrane, a feature reported previously for other NAD(P)H-consuming reactions at the plasma membrane (Lin 1982;Doke 1983;Doke and Chai 1985;Vianello and Macri 1991;Hicks and Morre 1998;Minibayeva et al 1998). This does not exclude the possibility that the enzyme normally accepts NADH from the cytoplasmic side of the membrane.…”

Spatiotemporal Patterning of Reactive Oxygen Production and Ca2+ Wave Propagation in Fucus Rhizoid Cells

“…Reactive oxygen species (ROS) are produced by plant and animal cells in response to a range of stimuli (Bac et al, 1997;Minibayeva et al, 1998;Tan et al, 1998;Grant and Loake, 2000). Such oxidative bursts can underlie antimicrobial activity or downstream responses such as modulation of gene expression and cell cycle control (Finkel, 1998;Reichheld et al, 1999;Bowie and O'Neill, 2000;Desikan et al, 2000;Shackelford et al, 2000).…”

Superoxide production as a stress response of wounded root cells: ESR spin-trap and acceptor methods

“…The initial phase involving an increase in the superoxide production may be considered as an unspecific stress response. Following this, there comes the phase of adaptation characterized by a 0.5-fold reduction of the superoxide level, the import of K+ ions from incubation medium into the cells and the restoration of membrane potential [23]. Similar changes were shown to occur in tobacco cells treated with the elicitor cryptogen [24].…”

“…Dynamics of the superoxide content over 6 h incubation of the excised roots is well correlated with variations of physiological parameters describing the ionic permeability of plasma membrane. In the early stage (1-2 h after excision of roots) depolarization of the plasmalemma, K+ ion efflux and an enhancement of free fatty acid content were observed [22,23]. These results demonstrate that the development of wound stress in the excised wheat roots is a biphasic process.…”

“…3c) and suppression of epinephrine-adrenochrome conversion (data not shown). In our earlier paper [23] it was demonstrated that the inhibitors of flavoprotein activity, a b C^M^^' t^^1Jln^^^^níwvtilvM^..rvwUWt chlorpromazine and quinine, depressed the Oz -synthesis in the root cells. This fact allowed us to believe that flavoprotein is possibly involved in the superoxide production.…”