Involvement of plasma-membrane NADPH oxidase in abscisic acid- and water stress-induced antioxidant defense in leaves of maize seedlings

Abstract

The roles of the plasma-membrane (PM) NADPH oxidase in abscisic acid (ABA)- and water stress-induced antioxidant defense were investigated in leaves of maize ( Zea mays L.) seedlings. Treatment by exogenous ABA (100 micro M ABA) or osmotic stress (-0.7 MPa induced by polyethylene glycol) significantly increased the activity of the PM NADPH oxidase, the production of leaf O(2)(-), the activities of several antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase), and the contents of antioxidant metabolites (ascorbate and reduced glutathione). Pretreatment with three different inhibitors of NADPH oxidase (diphenylene iodonium, imidazole and pyridine) or an inhibitor of ABA biosynthesis (tungstate) reduced the increase in the activity of the PM NADPH oxidase and the production of leaf O(2)(-), and the capacity of antioxidant defense systems mediated by ABA. The inhibitory effects above caused by tungstate were reversed by exogenous ABA. These data indicate that NADPH oxidase is involved in the ABA-induced production of active oxygen species (AOS), and our results depict a minimal chain of events initiated by water stress-induced ABA accumulation, which then triggers the production of AOS by membrane-bound NADPH oxidase, resulting in the induction of antioxidant defense systems against oxidative damage in plants.

Comparison of ROS formation and antioxidant enzymes in Cleome gynandra (C4) and Cleome spinosa (C3) under drought stress

“…NOX acts as a supplier of ROS which is needed for signal transduction and stress perception in plants [64]. Many studies have shown that NOX activity increases under drought stress [34,65]. In agreement with these studies, we also observed a strong increase in NOX activity in both Cleome species.…”

“…In this study, the level of lipid peroxidation was determined by measuring MDA content, which is a product of lipid peroxidation. Maintenance of membrane functionality due to unchanged MDA content in C. gynandra under drought stress may be attributed to the adequate response of the antioxidant system to drought-induced oxidative damage, as also observed in some other stress-tolerant plants such as maize [34], sorghum [5] and Plantago maritima [67]. On the other hand, in C. spinosa, increased MDA depending on time of drought treatment showed that the effect of antioxidant defence was insufficient under stress conditions to suppress the increasing ROS production.…”

“…NOX (EC 1.6.3.1) activity was measured according to Jiang and Zhang [34]. The assay medium contained 50 mM Tris-HCl buffer, pH 7.5, 0.5 mM XTT, 100 M NADPH·Na 4 and 20 g of protein.…”

Does a terminal drought tolerance QTL contribute to differences in ROS scavenging enzymes and photosynthetic pigments in pearl millet exposed to drought?

“…However, ROS may also serve as a molecules transducting drought signal and so enhance the plant stress defense mechanisms (Guan and Scandalios, 1998;Guan et al, 2000;Yoshimura et al, 2000;Jiang and Zhang et al, 2002;Noctor, 2005;Suzuki and Mittler, 2006). There are basically two detoxification mechanisms plants have developed to scavenge free ROS (Scandalios, 1997;Shalata and Tal, 1998;Procházková et al, 2001) (i) Non-enzymatic radical scavengers, e.g.…”

Cross-talk between calcium-calmodulin and nitric oxide in abscisic acid signaling in leaves of maize plants

“…Accumulating evidence indicates that ABAenhanced water stress tolerance is, at least in part, due to the induction of antioxidant defense systems [3][4][5][6]. Previous studies have shown that NADPH oxidase, hydrogen peroxide (H 2 O 2 ), nitric oxide (NO), calcium (Ca 2+ )-calmodulin (CaM), and mitogen-activated protein kinase (MAPK) are required for ABA-induced up-regulation in the activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) and glutathione reductase (GR) in leaves of maize plants [7][8][9][10][11].…”