Transcriptomic Footprints Disclose Specificity of Reactive Oxygen Species Signaling in Arabidopsis  

Abstract

Reactive oxygen species (ROS) are key players in the regulation of plant development, stress responses, and programmed cell death. Previous studies indicated that depending on the type of ROS (hydrogen peroxide, superoxide, or singlet oxygen) or its subcellular production site (plastidic, cytosolic, peroxisomal, or apoplastic), a different physiological, biochemical, and molecular response is provoked. We used transcriptome data generated from ROS-related microarray experiments to assess the specificity of ROS-driven transcript expression. Data sets obtained by exogenous application of oxidative stress-causing agents (methyl viologen, Alternaria alternata toxin, 3-aminotriazole, and ozone) and from a mutant (fluorescent) and transgenic plants, in which the activity of an individual antioxidant enzyme was perturbed (catalase, cytosolic ascorbate peroxidase, and copper/ zinc superoxide dismutase), were compared. In total, the abundance of nearly 26,000 transcripts of Arabidopsis (Arabidopsis thaliana) was monitored in response to different ROS. Overall, 8,056, 5,312, and 3,925 transcripts showed at least a 3-, 4-, or 5-fold change in expression, respectively. In addition to marker transcripts that were specifically regulated by hydrogen peroxide, superoxide, or singlet oxygen, several transcripts were identified as general oxidative stress response markers because their steady-state levels were at least 5-fold elevated in most experiments. We also assessed the expression characteristics of all annotated transcription factors and inferred new candidate regulatory transcripts that could be responsible for orchestrating the specific transcriptomic signatures triggered by different ROS. Our analysis provides a framework that will assist future efforts to address the impact of ROS signals within environmental stress conditions and elucidate the molecular mechanisms of the oxidative stress response in plants.

Molecular mechanisms of desiccation tolerance in the resurrection glacial relic Haberlea rhodopensis

“…Among the antioxidant enzymes, catalase has been shown to function as a cellular sink for H 2 O 2 and to be of paramount importance for protection against oxidative stress [60]. As H 2 O 2 is diffusible and can cross biological membranes through peroxiporins [61], peroxisomal calatases can decompose excess H 2 O 2 produced in other compartments. H. rhodopensis has more catalases than A. thaliana and most other species with sequenced genomes; it also has more genes encoding superoxide dismutases, monodehydroascorbate reductases, and glutathione reductases, supporting the notion of a potent and redundant antioxidant gene network.…”

Safeners recruit multiple signalling pathways for the orchestrated induction of the cellular xenobiotic detoxification machinery in Arabidopsis

“…There is a growing body of evidence, however, that WRKYs are critically involved also in abiotic stress responses, oxidative stress in particular (Miller, Shulaev & Mittler 2008). This is certainly the case for WRKY6 and 75 which were found to be co-induced in seven of nine oxidative stressrelated gene expression profiling experiments in Arabidopsis (Gadjev et al 2006). Interestingly, within the set of TGA/ SA-independent genes, eight WRKYs (-6, -22, -31, -33, -40, -45, -48, -75) were induced after safener treatment, including WRKY6 and 75.…”

Singlet Oxygen Is the Major Reactive Oxygen Species Involved in Photooxidative Damage to Plants

“…3C). Additional evidence of a close correlation between 1 O 2 accumulation and cell death in ch1 was obtained by monitoring H 2 O 2 and 1 O 2 -specific marker genes (Gadjev et al, 2006;Laloi et al, 2007). We analyzed the relative expression levels of two H 2 O 2 -responsive genes and two 1 O 2 -responsive genes (Fig.…”

“…Similarly, in the conditional flu mutant increased plastid 1 O 2 levels were shown to induce a genetic program leading to cell death (op den Camp et al, 2003;Wagner et al, 2004). Nevertheless, whereas careful monitoring of gene expression on the whole-genome level enables to pinpoint specific signaling capacities for diverse ROS (Mittler et al, 2004;Gadjev et al, 2006), it remained impossible to discriminate between the oxidative damaging effects on cellular components of different ROS.…”