title: The evolution of reactive oxygen species metabolism.
abstract: Reactive oxygen species (ROS) play a key role in the regulation of many biological processes in plants. Nonetheless, they are considered highly reactive and toxic to cells. Owing to their toxicity, as well as their important role in signaling, the level of ROS in cells needs to be tightly regulated. The ROS gene network, encoding a highly redundant arsenal of ROS scavenging mechanisms and an array of enzymes involved in ROS production, regulates ROS metabolism and signaling in plants. In this article, we review the role of the ROS gene network in plants and examine how it evolved. We identify key components of the ROS gene network in organisms that likely originated as early as 4.1-3.5 billion years ago, prior to the great oxidation event that resulted from the rise of cyanobacteria on Earth. This estimate concurs with recent evidence for the appearance of oxygenic photosynthetic organisms on Earth, suggesting that low and/or localized levels of photosynthetically produced oxygen necessitated the emergence of ROS scavenging mechanisms to protect life. Life forms have therefore evolved in the presence of ROS on Earth for at least 3.8-3.6 billion years, highlighting the intimate relationship that exists today between many physiological and developmental processes and ROS.
authors.affiliation: Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA.
authors.forename: Madhuri A
authors.initials: MA
authors.lastname: Inupakutika
authors.affiliation: Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA.
authors.forename: Soham
authors.initials: S
authors.lastname: Sengupta
authors.affiliation: Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA.
authors.forename: Amith R
authors.initials: AR
authors.lastname: Devireddy
authors.affiliation: Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA.|Department of Mathematics, University of North Texas, Denton, TX 76203, USA.
authors.forename: Rajeev K
authors.initials: RK
authors.lastname: Azad
authors.affiliation: Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA. ron.mittler@unt.edu.
authors.forename: Ron
authors.initials: R
authors.lastname: Mittler
mesh_terms: D060387:Ascorbate Peroxidases / Q000235:genetics / Q000378:metabolism; D005075:Biological Evolution; D053263:Gene Regulatory Networks / Q000235:genetics / Q000502:physiology; D017343:Genes, Plant / Q000502:physiology; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D010944:Plants / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D017382:Reactive Oxygen Species; D060387:Ascorbate Peroxidases; D019255:NADPH Oxidases; C022709:superoxide-forming enzyme
keywords: Ascorbate peroxidase; NADPH oxidase; evolution; great oxidation event; reactive oxygen species; superoxide dismutase.