Aluminum-induced changes in reactive oxygen species accumulation, lipid peroxidation and antioxidant capacity in wheat root tips

Abstract

The present study investigated the effects of aluminum on lipid peroxidation, accumulation of reactive oxygen species and antioxidative defense systems in root tips of wheat (Triticum aestivum L.) seedlings. Exposure to 30 μM Al increased contents of malondialdehyde, H 2 O 2 , suproxide radical and Evans blue uptake in both genotypes, with increases being greater in Al-sensitive genotype Yangmai-5 than in Al-tolerant genotype Jian-864. In addition, Al treatment increased the activity of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), glutathione reductase (GR) and glutathione peroxidase (GPX), as well as the contents of ascorbate (AsA) and glutathione (GSH) in both genotypes. The increased activities SOD and POD were greater in Yangmai-5 than in Jian-864, whereas the opposite was true for the activities of CAT, APX, MDHAR, GR and GPX and the contents of AsA and GSH. Consequently, the antioxidant capacity in terms of 2,2-diphenyl-1-picrylhydrazyl (DPPH)-radical scavenging activity and ferric reducing/antioxidant power (FRAP) was greater in Jian-864 than in Yangmai-5.

Antioxidant system response induced by aluminum in two rice cultivars

“…The production of ROS induced by Al is well-known (Yamamoto et al, 2002;Achary et al, 2008;Xu et al, 2012), although the role of oxidative stress in Al toxicity is still unclear. Although Al is not a transition element and does not participate in redox reactions, it has pro-oxidant activity (Exley, 2004), promoting increased concentration of ROS and changing the redox state of the metabolic system in cells (Achary et al, 2008;Ma et al, 2012;Xu et al, 2012).…”

“…Although Al is not a transition element and does not participate in redox reactions, it has pro-oxidant activity (Exley, 2004), promoting increased concentration of ROS and changing the redox state of the metabolic system in cells (Achary et al, 2008;Ma et al, 2012;Xu et al, 2012). However, in tolerant plants, even in the presence of toxic levels of Al, the levels of ROS in plant tissues do not significantly change, indicating the existence of efficient antioxidant defense systems to this metal (Giannakoula et al, 2010).…”

“…Al can bind to phospholipids and/or modify the fatty acid composition of the plasma membrane, reducing its fluidity and increasing its permeability (Peixoto et al, 2001;Vitorello et al, 2005). Moreover, Al can cause oxidative stress, resulting in the production and accumulation of ROS, which cause peroxidation of membrane lipids (Meriga et al, 2004;Sharma and Dubey, 2007;Ma et al, 2012;Xu et al, 2012). Contrary to our expectations, in this study, the exposure of plants to Al resulted in a decrease in the levels of the two ROS analyzed, especially H 2 O 2 .…”

“…Recent research suggests that at least part of Al toxicity is due to oxidative stress caused by this ion; therefore, the tolerance of plants to Al may be related to the activity of the plants' antioxidant systems (Sharma and Dubey, 2007;Giannakoula et al, 2010;Panda and Matsumoto, 2010;Ma et al, 2012;Xu et al, 2012). This system involves enzymatic and non-enzymatic antioxidant mechanisms for removal of ROS produced during oxidative stress (Gratão et al, 2005).…”

“…Among the metabolites that participate in the non-enzymatic defense system are AA, GSH, α-tocopherol and carotenoids (Gratão et al, 2005). AA and GSH are powerful antioxidants that directly react with various types of ROS (Foyer and Noctor, 2011;Xu et al, 2012) and/or serve as electron donors for key enzymes of the antioxidant enzymatic system such as APX and GPX (Noctor et al, 2012). The joint action of both the enzymatic and non-enzymatic antioxidant defense systems allows for plants to efficiently combat the excess ROS generated under conditions of oxidative stress induced by biotic or abiotic stressors.…”