Oxidative stress induced by cadmium in Nicotiana tabacum L.: effects on growth parameters, oxidative damage and antioxidant responses in different plant parts

Abstract

Tobacco (Nicotiana tabacum L.) is a tolerant species that accumulates cadmium. We studied the effect of Cd (0, 10, 25, 50, 100 lM) on growth parameters, chlorophyll and proline contents, enzymatic antioxidative response and lipid peroxidation of tobacco plants grown in hydroponic culture for 11 days to clarify the strategy of plant response against oxidative stress caused by this heavy metal. Cadmium accumulated more in roots than in shoots. Plant growth was not significantly affected by the cadmium concentrations used. Young leaves were more affected, showing visible chlorosis and a significant decrease in chlorophyll content at high Cd concentrations. Dry weight of both leaves and roots increased indicating a lower capacity for roots to absorb water. An increase in malondialdehyde levels was observed, indicating that lipid peroxidation occurred as a result of ROS formation. The activity of guaiacol peroxidase in leaves increased, indicating that it was very important in the scavenging of H 2 O 2 , while superoxide dismutase activity only increased in old leaves. Ascorbate peroxidase showed constant activity levels in tobacco leaves, suggesting that the ascorbate-glutathione pathway was less important as a defense mechanism.

Responses of Ruderal Verbascum olympicum Boiss. (Scrophulariaceae) Growing under Cadmium Stress

“…The formation of ROS induces lipid peroxidation due to the removal of hydrogen from unsaturated fatty acids, leading to the formation of lipid radicals and reactive aldehydes [17] and causing destruction of the lipid bilayer and membrane proteins [66]. Leaf MDA levels were significantly increased as a function of Cd treatment in our study, suggesting Cd-induced membrane damage in V. olympicum and in agreement with the results of studies reporting membrane damage caused by Cd [5,9,11].…”

“…2). It has also been reported that Cd translocation to the shoots may vary considerably among different species [11,44].…”

Growth of Four Varieties of Barley (<i>Hordeum vulgare</i> L.) in Soils Contaminated with Heavy Metals and Their Effects on Some Physiological Traits

“…The low and intermediate concentrations of Zn and Cd favored growth and increased the dry weight of the shoots and roots in all varieties of barley studied. Other studies have also demonstrated that plant growth in some species can be stimulated by high concentrations of Zn and other metals [23,24]. One possible explanation is that these species may have higher requirements of Zn and Cd than other plant types.…”

Characterization of Plant Antioxidative System in Response to Abiotic Stresses: A Focus on Heavy Metal Toxicity

“…Proline has been reported to improve plant resistance to oxidative stress by scavenging ROS (namely by quenching singlet oxygen and hydroxyl radicals), increasing the activity of antioxidative enzymes and protecting them and maintaining redox homeostasis (Matysik et al, 2002), and they could also participate in signalling pathways that regulate stress related genes (Khedr et al, 2003). Although the concentration of proline has been shown to increase under heavy metal stress in certain plants (Martins et al, 2011), its exact role in heavy metal detoxification is unclear as, under certain conditions, it could be only an indirect response due to heavymetal induced disturbances in plant water balance (Schat et al, 1997).…”