Genome-wide analysis of glutathione reductase (GR) genes from rice and Arabidopsis

Abstract

Plant cells and tissues remain always on risk under abiotic and biotic stresses due to increased production of reactive oxygen species (ROS). Plants protect themselves against ROS induced oxidative damage by the upregulation of antioxidant machinery. Out of many components of antioxidant machinery, glutathione reductase (GR, EC 1.6.4.2) and glutathione (GSH, γ-Glu-Cys-Gly) play important role in the protection of cell against oxidative damage. In stress condition, the GR helps in maintaining the reduced glutathione pool for strengthening the antioxidative processes in plants. Present study investigates genome wide analysis of GR from rice and Arabidopsis. We were able to identify 3 rice GR genes (LOC_Os02 g56850, LOC_Os03 g06740, LOC_Os10 g28000) and 2 Arabidopsis GR genes (AT3G54660, AT3G24170) from their respective genomes on the basis of their annotation as well as the presence of pyridine nucleotide-disulphide oxidoreductases class-I active site. The evolutionary relationship of the GR genes from rice and Arabidopsis genomes was analyzed using the multiple sequence alignment and phylogenetic tree. This revealed evolutionary conserved pyridine nucleotide-disulphide oxidoreductases class-I active site among the GR protein in rice and Arabidopsis. This study should make an important contribution to our better understanding of the GR under normal and stress condition in plants.

Keywords: Arabidopsis; abiotic stress; chromosome localization; genome-wide analysis; glutathione reductase; homology modeling; phylogenetic analysis; rice.

Figure 1. Antioxidant pathway mediated by Glutathione reductase in response to external and inner cellular stresses. GSH is oxidative product of various signaling pathways which is reduced by GSH. APX, ascorbate peroxidase; DHA dehydroascorbate; ASA ascorbic acid; DHAR, dehydroascorbate reductase; GSSG, oxidized glutathione; GHS, reduced glutathione; GR, glutathione reductase.

Figure 2. (A) Multiple sequence alignment of GR protein sequences, black box showing conserved Pyridine nucleotide-disulphide oxidoreductases class-I active site. (B) Phylogenetic analysis of rice and Arabidopsis GR genes. The tree was constructed using neighbor-joining method using 1000 bootstrap replicates. Homologous gene pairs have grouped in solid boxes while the orthologs were grouped using shaded boxes. (C and D) Genome organization of rice and Arabidopsis GR genes. The figure represents the arrangement of 3 and 2 GR genes on 2 chromosomes of rice (C) and single chromosomes of Arabidopsis (D), respectively.

Figure 3. Homology modeling of represented GR protein from rice and Arabidopsis. (A and D) represents 3D protein structure model of GR from rice and Arabidopsis, respectively. Round circle depicts Pyridine nucleotide-disulphide oxidoreductases class-I active site. (B and C) depicts highlighted Pyridine nucleotide-disulphide oxidoreductases class-I active site and NAD binding site, respectively in rice GR protein. (E) FAD binding site and redox active site are shown. (F) Proton acceptor site and NADP binding sites are shown.

Figure 4. Expression profile of the rice and Arabidopsis GR genes in various stress conditions and developmental stages depicted as a heat map (A) expression profile of rice GR under various anatomical characters and abiotic stress conditions. (B) Expression profile of Arabidopsis GR under various developmental stages. (C and D) Expression profile of Arabidopsis GR under various anatomical characters and abiotic stress conditions, respectively.