The influence of nitrogen supply on antioxidant enzymes in plant roots

Abstract

Plants of Zea mays L., Hordeum vulgare L. and Arabidopsis thaliana (L.) Heynh. were grown at different concentrations of nitrogen, as NH4NO3, and the antioxidant enzyme activities and quantities in the roots, were studied. Maize plants were grown at 1 and 10 mM N for 32 d after germination and their roots were analysed by native PAGE for the isoenzymic profiles of glutathione reductase (GR; EC 1.6.4.2), catalase (CAT; EC 1.11.1.6) and superoxide dismutase (SOD; EC 1.15.1.1) and by spectrophotometric assays for total activity of CAT and GR. Barley and A. thaliana plants were grown at five N concentrations (0.25, 0.5, 1, 10 and 20 mM) for 27 and 26 d, respectively, and the isoenzymic profile of the three enzymes were analysed in their roots. The number of GR isoforms in the three plant species was increased at high N supply compared with low N. In addition, the CAT and GR activities detected in the roots were increased in plants grown at higher N. The increase in activity and number of bands of GR at high N in the roots of all three plants studied was not accompanied by a change in activity or the number of SOD isoforms. The possibility that the application of high N promotes the formation of reactive oxygen species by stimulating an increased rate of growth is discussed.

Perturbations of Amino Acid Metabolism Associated with Glyphosate-Dependent Inhibition of Shikimic Acid Metabolism Affect Cellular Redox Homeostasis and Alter the Abundance of Proteins Involved in Photosynthesis and Photorespiration

“…In particular, uncertainties remain concerning how the photosynthetic cell balances energy-producing and energy-requiring processes in order to maintain cellular redox status, particularly in stressful conditions (Foyer et al, 2009). For example, there are conflicting reports in the literature concerning the effects of nitrogen supply on cellular redox status and antioxidant enzymes, with some studies reporting that antioxidant enzyme activities increase as the nitrogen supply is increased (Medici et al, 2004) while other studies show either no effect (Domínguez-Valdivia et al, 2007) or that plants experiencing nitrogen deficiency have a higher abundance of antioxidant enzymes (Ramalho et al, 1998). Several lines of evidence suggest that a close relationship exists between cellular redox state and amino acid metabolism.…”

Variation in the ureide content of Jack Bean during the reproductive stages in response to nitrate

“…Stress conditions that impair N assimilation in several distinct plant species, including legume species of both ureide-and amide-exporting categories, have been shown to lead to specific changes in the amino acid composition of the xylem (do Amarante et al, 2006). Excess nitrogen supply has also been shown to induce high levels of oxidative stress in maize roots (Medici et al, 2004). In C. ensiformis, the nitrate levels in organs seemed to be influenced linearly by the nitrate dose supplied, without indication of any pattern with regard to changes in development, since nitrate goes up dramatically from T 0 to T 2 in all organs in S1, but goes down from T 1 to T 2 in S2 (Table 1).…”

“…Mineral nutrition is essential for plant growth (Medici et al, 2004;2005;Garcia et al, 2006;Oroka and Omoregie, 2007); nitrogen is frequently the limiting mineral nutrient for plant productivity (Gaiad et al, 2006;Lea and Azevedo, 2006) and it is important in animal nutrition (Huaynate et al, 2006). On the other hand, it is important to note that the production of nitrogenous waste by livestock agriculture is a significant environmental concern in terms of pollution of land and water (Kingston-Smith et al, 2006).…”

Root system characteristics of Marandu palisadegrass supplied with nitrogen and magnesium rates

“…According to Medici et al (2004), plants have several mechanisms to avoid ROS production, such as preventing N excess and the use of anti oxidant enzymes. Manarin & Monteiro (2002) evaluated the growth of Mombaça guineagrass and observed that the increase in N rates resulted in linear increase in N concentration in roots, highlighting the ability of plants to store N in roots, which is a result of the balance between the N concentration in above ground plant and concentration in roots (Overman & Scholtz, 2003).…”