Several reactive oxygen species (ROS) are continuously produced in plants as byproducts of aerobic metabolism. Depending on the nature of the ROS species, some are highly toxic and rapidly detoxified by various cellular enzymatic and nonenzymatic mechanisms. Whereas plants are surfeited with mechanisms to combat increased ROS levels during abiotic stress conditions, in other circumstances plants appear to purposefully generate ROS as signaling molecules to control various processes including pathogen defense, programmed cell death, and stomatal behavior. This review describes the mechanisms of ROS generation and removal in plants during development and under biotic and abiotic stress conditions. New insights into the complexity and roles that ROS play in plants have come from genetic analyses of ROS detoxifying and signaling mutants. Considering recent ROS-induced genome-wide expression analyses, the possible functions and mechanisms for ROS sensing and signaling in plants are compared with those in animals and yeast.

REACTIVE OXYGEN SPECIES: Metabolism, Oxidative Stress, and Signal Transduction

http://paymanhassibi.persiangig.com/document/mittler%20oxidative.pdf

Oxidative stress, antioxidants and stress tolerance

Reactive oxygen species and antioxidant machinery in abiotic stress tolerance in crop plants

http://biol.unt.edu/~rmittler/Papers/Reactive%20oxygen%20gene%20network%20of%20plants.pdf

Reactive oxygen gene network of plants

Reactive oxygen species (ROS) are produced as a normal product of plant cellular metabolism. Various environmental stresses lead to excessive production of ROS causing progressive oxidative damage and ultimately cell death. Despite their destructive activity, they are well-described second messengers in a variety of cellular processes, including conferment of tolerance to various environmental stresses. Whether ROS would serve as signaling molecules or could cause oxidative damage to the tissues depends on the delicate equilibrium between ROS production, and their scavenging. Efficient scavenging of ROS produced during various environmental stresses requires the action of several nonenzymatic as well as enzymatic antioxidants present in the tissues. In this paper, we describe the generation, sites of production and role of ROS as messenger molecules as well as inducers of oxidative damage. Further, the antioxidative defense mechanisms operating in the cells for scavenging of ROS overproduced under various stressful conditions of the environment have been discussed in detail.

https://downloads.hindawi.com/archive/2012/217037.pdf

Reactive Oxygen Species, Oxidative Damage, and Antioxidative Defense Mechanism in Plants under Stressful Conditions

Adaptation to environmental changes is crucial for plant growth and survival. However, the molecular and biochemical mechanisms of adaptation are still poorly understood and the signaling pathways involved remain elusive. Active oxygen species (AOS) have been proposed as a central component of plant adaptation to both biotic and abiotic stresses. Under such conditions, AOS may play two very different roles: exacerbating damage or signaling the activation of defense responses. Such a dual function was first described in pathogenesis but has also recently been demonstrated during several abiotic stress responses. To allow for these different roles, cellular levels of AOS must be tightly controlled. The numerous AOS sources and a complex system of oxidant scavengers provide the flexibility necessary for these functions. This review discusses the dual action of AOS during plant stress responses.

Dual action of the active oxygen species during plant stress responses.

As an unfortunate consequence of aerobic life, active oxygen species (AOS) are formed by partial reduction of molecular oxygen. Plants possess a complex battery of enzymatic and non-enzymatic antioxidants that can protect cells from oxidative damage by scavenging AOS. It is becoming evident that AOS, which are generated during pathogen attack and abiotic stress situations, are recognized by plants as a signal for triggering defence responses. An overview of the literature is presented on the signalling role of AOS in plant defence responses, cell death, and development. Special attention is given to AOS and redox-regulated gene expression and the role of kinases and phosphatases in redox signal transduction.

Signal transduction during oxidative stress

The role of active oxygen species in plant signal transduction

The molecular mechanisms by which plants acclimate to oxidative stress are poorly understood. To identify the processes involved in acclimation, we performed a comprehensive analysis of gene expression in Nicotiana tabacum leaves acclimated to oxidative stress. Combining mRNA differential display and cDNA array analysis, we estimated that at least 95 genes alter their expression in tobacco leaves acclimated to oxidative stress, of which 83% are induced and 17% repressed. Sequence analysis of 53 sequence tags revealed that, in addition to antioxidant genes, genes implicated in abiotic and biotic stress defenses, cellular protection and detoxification, energy and carbohydrate metabolism, de novo protein synthesis, and signal transduction showed altered expression. Expression of most of the genes was enhanced, except for genes associated with photosynthesis and light-regulated processes that were repressed. During acclimation, two distinct groups of coregulated genes (“early-” and “late-response” gene regulons) were observed, indicating the presence of at least two different gene induction pathways. These two gene regulons also showed differential expression patterns on an oxidative stress challenge. Expression of “late-response” genes was augmented in the acclimated leaf tissues, whereas expression of “early-response” genes was not. Together, our data suggest that acclimation to oxidative stress is a highly complex process associated with broad gene expression adjustments. Moreover, our data indicate that in addition to defense gene induction, sensitization of plants for potentiated gene expression might be an important factor in oxidative stress acclimation.

https://www.pnas.org/content/pnas/99/16/10870.full.pdf

Eva Vranová

Papers

Dual action of the active oxygen species during plant stress responses.

Signal transduction during oxidative stress

The role of active oxygen species in plant signal transduction

Comprehensive analysis of gene expression in Nicotiana tabacum leaves acclimated to oxidative stress

The role of active oxygen species in plant signal transduction