Changes in the antioxidant and glyoxalase enzyme activities in leaves of two Moroccan sorghum ecotypes with differential tolerance to nitrogen stress

Abstract

Nitrogen stress as well as other stresses can negatively impact the plant development and metabolism. Generally, stress factors increase the reactive oxygen species (ROS) and methylglyoxal (MG) production, which may, in the absence of effective protective mechanisms, induce irreparable metabolic dysfunction and death. The effect of different amounts (from deficiency to excess) of nitrate, ammonium or nitrate combined to ammonium, on enzyme activities of antioxidant and methylglyoxal detoxification systems of two sorghum ecotypes (3P4 and 4P11) was studied. The N supply was performed per pot during the sowing step using potassium nitrate and/or ammonium sulfate. Six N treatments were applied using 120, 240 and 480 Kg ha-1 of ammonium or nitrate and three other treatments were applied using 120 kg ha-1 nitrate combined to 120, 240 and 480 kg ha-1 of ammonium. The specific activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione reductase (GR), glyoxalase I (Gly I) and glyoxalase II (Gly II) were investigated. Results showed that, ammonium excess and N-deficient conditions increased the contents of malondialdehyde (MDA), and induced the enzyme activities of ROS and MG detoxification systems, supporting the sorghum's ability to counteract the negative effect of N stress (deficit and excess). We have also shown that the SOD, CAT, GR and Gly I enzyme activities were higher in the 4P11 ecotype compared to the 3P4 ecotype. These results indicate that sorghum ecotypes exhibit differential tolerance to N stress and suggest that the 4P11 ecotype has higher capacity to cope with N stress.

Tolerance and adaptation characteristics of sugar beet ( Beta vulgaris L.) to low nitrogen supply

“… 42 , 43 In this study, it was shown that the activities of SOD and APX were significantly higher in 780016B/12 superior (F) than in 92011 (G) under low nitrogen stress ( Figure 8a, d ). This kind of antioxidant defense system helps to protect photosynthetic organs from oxidative stress induced by N deficiency, 44 indicating that these two antioxidant enzymes may be closely related to the LN tolerance capacity of 780016B/12 superior (F). However, the POD activity of 92011 (G) was much higher than that of 780016B/12 superior (F).…”

From methylglyoxal to pyruvate: a genome-wide study for the identification of glyoxalases and D-lactate dehydrogenases in Sorghum bicolor

“…In fact, a comparative study conducted in the two sorghum genotypes viz. 3P4 and 4P11, has revealed an increase in GLYI and GLYII activities in the plants subjected to both N-deficient and N-excess conditions, especially in the case, where ammonium was used as a N source [58]. In a similar context, the impact of MG in contributing towards NH 4 + toxicity symptoms in Arabidopsis has been recently studied [59].…”

The effect of foliar application of Ulva rigida extract on the growth and biochemical parameters of wheat plants

“…When plants are exposed to stress factors, an increase of the reactive oxygen species (ROS) is observed [47]. To maintain ROS under normal levels, plants can evolve a multitude of protective mechanisms, among of the them, the activation of the antioxidative enzymes such as, SOD, GST and GR [48].…”

“…The GSH is used in several redox reactions, among of them, those responsible for the amino acid transport and protein and DNA synthesis [51]. High ratio of GSH/GSSG was also reported to be required for accelerating the H2O2 scavenging pathway, especially when plants are facing stressful conditions [48,52]. The increase in plant height and fresh weight at the concentration of 25% of seaweed could explain the high level of the GR enzyme at this condition, to allow synthesis of high levels of GSH required for the metabolic pathways implicated in biomass production and also to cope with the eventual stressful conditions that face wheat plants.…”

“…Our results indicated that GST activity increased only at the concentration of 50% of URE (Figure 7). It is known that GST may help reduce a wide range of organic hydroperoxides in the presence of GSH [48]. It has been shown that GST enzyme can protect plants exposed to salt stress and to encounter its effect against lipid peroxidation [53].…”