Abstract
Glutathione peroxidases (GPX) catalyze the reduction of H2O2 or organic hydroperoxides to water or corresponding alcohols using reduced glutathione, which plays an essential role in ROS (reactive oxygen species) homeostasis and stress signaling. Thellungiella salsuginea (Eutrema salsugineum), a relative of Arabidopsis thaliana, displays an extremely high level of tolerance to salt, drought, cold and oxidative stresses. The enzymatic antioxidant systems may contribute to the stress tolerance of T. salsuginea. In the present study, we aimed at understanding the roles of the antioxidant enzymes in T. salsuginea by focusing on the GPX family. We identified the eight GPX genes in T. salsuginea, and the structure of the N-terminal domains indicated their putative chloroplastic, mitochondrial and cytoplasmic location. The exon-intron organization of these genes exhibited a conserved pattern among plant GPX genes. Multiple environmental stresses and hormone response related cis-acting elements were predicted in the promoters of TsGPX genes. The gene and protein expression profiles of TsGPXs in response to high level of salinity and osmotic stresses, in leaves and roots of T. salsuginea were investigated using real-time RT-PCR and western blotting analysis. Our result showed that different members of the GPX gene family were coordinately regulated under specific environmental stress conditions, and supported the important roles of TsGPXs in salt and drought stress response in T. salsuginea.
Highlights
In cells, reactive oxygen species (ROS) such as superoxide (O2−), hydrogen peroxide (H2O2), and hydroxyl radical (OH) are produced during basic metabolic processes like respiration and photosynthesis
Considering that plant glutathione peroxidases (GPX) genes were reported to be involved in responses to various environmental stresses [10,17,18,19], we analyzed the promoter regions of the eight Thellungiella salsuginea glutathione peroxidase (TsGPX) genes to locate putative cis-acting regulatory elements related to stress and hormone signaling (Table 2) using
Ts GPX genes, we investigated the expression profiles of TsGPX in T. salsuginea exposed to high salinity and osmotic stress treatments at the transcriptional level using quantitative RT-PCR
Summary
Reactive oxygen species (ROS) such as superoxide (O2−), hydrogen peroxide (H2O2), and hydroxyl radical (OH) are produced during basic metabolic processes like respiration and photosynthesis. Three GPX family studies were performed in A. thaliana [19], Lotus japonicas [20], and Populus trichocarpa [21]; these studies revealed that plant GPX family consists of multiple GPXs with distinct subcellular location and functions, and that members exhibit different tissue-specific expression patterns and environmental stress responses, functioning coordinately in ROS scavenging. These works highlight the importance of GPX study at the genome-wide level. We examined the expression of TsGPX transcripts and proteins in T. salsuginea leaves and roots that were exposed to short-term salt and osmotic stresses
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