LAUSR

Abstract In the era of global environmental changes, high curiosity in identifying and characterizing new antioxidant enzymes in plants has been witnessed. Previous studies reported the pivotal role played by Glutathione reductase (GR) in maintaining the reduced glutathione pool during stress. However, the knowledge of GR family members and their evolutionary and functional characteristics in oilseed species is limited. In this study, 6 and 4 GRs were identified from Brassica juncea and B. rapa genomes, respectively. Phylogenetic analysis of protein sequences showed diversification of this gene family into cytosolic and chloroplastic GR. Duplication of a single ancestral gene might have led to the diversification of cytosolic and chloroplastic GR before the divergence of monocot and dicot. The cytosolic GRs consisted of complex gene architecture compared to the chloroplastic ones, which can increase their expression level. Chloroplastic GRs showed the presence of N-terminal signal peptide. A high degree of conservation in gene and protein structures in the same sub-cellular compartment was observed. Notably, all cytosolic GRs were found to be differentially expressed under heat and drought stresses. Predicted cis-regulatory elements and miRNA targets were found to be associated with abiotic, biotic and developmental responses. Our study explained the structural and functional information of the GR family and the roles of different members in maintaining redox homeostasis under abiotic stresses. The study has laid the basic ground work for detailed functional characterization in future studies and developing improved oilseed varieties better adaptive to environmental stress conditions.