Recent insights into antioxidant defenses of legume root nodules

Abstract

SummaryLegume root nodules are sites of intense biochemical activity and consequently are at high risk of damage as a result of the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). These molecules can potentially give rise to oxidative and nitrosative damage but, when their concentrations are tightly controlled by antioxidant enzymes and metabolites, they also play positive roles as critical components of signal transduction cascades during nodule development and stress. Thus, recent advances in our understanding of ascorbate and (homo)glutathione biosynthesis in plants have opened up the possibility of enhancing N 2 fixation through an increase of their concentrations in nodules. It is now evident that antioxidant proteins other than the ascorbate-glutathione enzymes, such as some isoforms of glutathione peroxidases, thioredoxins, peroxiredoxins, and glutathione S-transferases, are also critical for nodule activity. To avoid cellular damage, nodules are endowed with several mechanisms for sequestration of Fenton-active metals (nicotianamine, phytochelatins, and metallothioneins) and for controlling ROS ⁄ RNS bioactivity (hemoglobins). The use of 'omic' technologies

An RNA Sequencing Transcriptome Analysis Reveals Novel Insights into Molecular Aspects of the Nitrate Impact on the Nodule Activity of Medicago truncatula

“…However, at this point in time, the nodule had most probably lost most of its nitrogen fixation activity. By contrast, Becana et al (2010) did not find any nitrate in the infected zone before 7 to 10 d after nitrate exposure. As yet, there have been no detailed time course studies done to show that the blocking of leghemoglobin precedes the decline in nitrogenase activity.…”

Copper microlocalisation, ultrastructural alterations and antioxidant responses in the nodules of white lupin and soybean plants grown under conditions of copper excess

“…These ROS possess an unpaired electron, and are highly reactive. The balance between the generation and scavenging of ROS is controlled by the antioxidant defence system (Becana et al, 2010); when this cannot cope with the level of ROS production, oxidative damage occurs.…”

Antioxidant and carbohydrate changes of two pomegranate cultivars under deficit irrigation stress

“…Enzymatic antioxidant system includes superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX). Non-enzymatic low molecular metabolites comprise ascorbate (ASA), glutathione (GSH), α-tocopherol, carotenoids and phenolic compound (Chaves & Oliveria, 2004;Mittler et al, 2004;Becana et al, 2010). The maintenance of a high antioxidant capacity to scavenge the toxic ROS has been linked to increased tolerance of plants to environmental stresses 3 Antioxidant and carbohydrate changes of pomegranate under deficit irrigation spectrophotometrically.…”