Induction of oxidative stress related responses inArabidopsis thalianafollowing uranium exposure

Abstract

Abstract. The reactive oxygen species (ROS)-signaling pathway is very important in heavy metal toxicity. Induction of the antioxidative defense mechanism, comprising ROS-scavenging enzymes and metabolites, in plants after environmental uranium contamination has been insufficiently studied in the past. This study aimed to analyze oxidative stress related responses in Arabidopsis thaliana after uranium exposure. Seventeen-day-old seedlings were exposed to 0, 0.1, 1, 10 and 100 M uranium for 3 days. After exposure to 100 M uranium, a decrease in fresh weight for leaves and roots was observed, leaves colored anthocyanous and roots were stunted and yellow. To reveal the importance of oxidative stress in uranium toxicity, alterations in ROS-scavenging enzymes were studied at protein and transcriptional level. Superoxide dismutase (SOD) capacities increased in leaves and roots after exposure to 100 M uranium but no differences were observed for catalase (CAT) capacities. Transcript levels of different SODs located at various cellular compartments were affected depending on the place of action. Gene expression of CAT in leaves and roots was also affected after uranium exposure. Results indicate that oxidative stress plays an important role in uranium toxicity but suggest that plant responses differ for leaves and roots.

The biochemical and histoanatomical response of some woodyspecies to anthropic impact in Suceava County, Romania

“…With different localizations (cytosol (Cu/ Zn SOD), plastids (Fe SOD), and mitochondria (Mn SOD)), the enzyme has different expressions not only in the plant cell but depending also on the site of U action. For example, Vanhoudt et al (2009) showed that SOD from cytosol provides a weak antioxidant action and that in roots plastids exhibits an improved antioxidant defense, which is not the case of leaf plastids; meanwhile, mitochondrial SOD easily copes with exposure to U. Our investigation focused on total SOD activity and is possible that one of the isoforms was strongly activated, while others were inhibited, which also explains the variation of SOD activity between the exposed species.…”

“…It should be taken into account that the enzymes are proteins and that a significant increase in leaf soluble protein concentration due to the accumulation of U in the soil was previously recorded (Shtangeeva et al, 2006). Vanhoudt et al (2009) stated that the level of antioxidant enzyme activity at the cellular level, activated by the presence of U in the environment, does not decrease when compared to the soluble proteins. These observations can be used also as significant elements that show the degree of soil pollution.…”

“…The modulatory effect of excess sulfur (S) on the enzymes composing the antioxidant system has been reported in various scientific papers (Keller, 1985;Khan et al, 2008;Oniciuc et al, 2012). Furthermore, although the data concerning plant responses to environmental contamination with uranium (U) are few, it is known that this exposure can cause an imbalance in the oxidative status of the plant cells (Vanhoudt et al, 2009). In addition, metals like iron (Fe) and copper (Cu) induce Fenton (Fe 2+ inversely correlated with altitude and the proportion of beech stand composition (Popa and Barbu, 2001).…”