Abstract
Reactive oxygen species (ROS) are byproducts of aerobic metabolism and may cause oxidative damage to biomolecules. Plants have a complex redox system, involving enzymatic and non-enzymatic compounds. The evolutionary origin of enzymatic antioxidant defense in plants is yet unclear. Here, we describe the redox gene network for A. thaliana and investigate the evolutionary origin of this network. We gathered from public repositories 246 A. thaliana genes directly involved with ROS metabolism and proposed an A. thaliana redox gene network. Using orthology information of 238 Eukaryotes from STRINGdb, we inferred the evolutionary root of each gene to reconstruct the evolutionary history of A. thaliana antioxidant gene network. We found two interconnected clusters: one formed by SOD-related, Thiol-redox, peroxidases, and other oxido-reductase; and the other formed entirely by class III peroxidases. Each cluster emerged in different periods of evolution: the cluster formed by SOD-related, Thiol-redox, peroxidases, and other oxido-reductase emerged before opisthokonta-plant divergence; the cluster composed by class III peroxidases emerged after opisthokonta-plant divergence and therefore contained the most recent network components. According to our results, class III peroxidases are in expansion throughout plant evolution, with new orthologs emerging in each evaluated plant clade divergence.
Highlights
Reactive oxygen species (ROS) are byproducts of normal metabolism of aerobic organisms, being produced in a constitutive and not controlled manner during photosynthesis in plants and during respiration in most living beings
We selected genes from six GO terms associated with redox metabolism, and for the second criteria, we selected A. thaliana genes annotated in PeroxiBase
We reconstructed the redox network of A. thaliana and tracked down the evolutionary roots of its genes to identify the origin of genetic redox system in plants
Summary
Reactive oxygen species (ROS) are byproducts of normal metabolism of aerobic organisms, being produced in a constitutive and not controlled manner during photosynthesis in plants and during respiration in most living beings. Many of those agents can imbalance ROS production, leading to oxidative stress[1] In spite of their toxic trait, ROS can be useful in plants acting as signaling molecules[2,3,4] and in defense against pathogens[5,6]. The non-enzymatic defenses act coordinately with several antioxidant enzymes, such as catalase (CAT), peroxidases (PER), superoxide dismutases (SOD), and other proteins with no catalytic activity, to maintain redox homeostasis[17]. Both enzymatic and non-enzymatic defenses work together in many known reactions, like the glutathione-ascorbate cycle, characterizing a redox-buffer system[18]. We found class III peroxidases as the most recent components of the network, showing that class III peroxidases cluster is in expansion in plants
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