Rice (Oryza sativa L.) tau class glutathione S-transferase (OsGSTU30) overexpression in Arabidopsis thaliana modulates a regulatory network leading to heavy metal and drought stress tolerance

Glutathione S-transferases (GSTs) are well-known enzymes due to their role in detoxification of xenobiotic compounds. However, their biochemical action is still not so clear in imparting tolerance to several abiotic stresses in crop plants. In our previous study, we observed that rice tau class OsGSTU30 plays a significant role in the detoxification of Cr(VI). Interestingly, q-RT PCR analysis also revealed higher expression of OsGSTU30 under drought conditions. In this study, we characterize OsGSTU30 in response to drought as well as heavy metal [Cr(VI)] stresses through overexpression in Arabidopsis thaliana. Biochemical and physiological analyses revealed that OsGSTU30 overexpression lines have improved tolerance against both stresses as compared to wild-type plants. Kinetic analysis and molecular docking confirmed that OsGSTU30 enzyme possesses both GST as well as glutathione peroxidase (GPx) like activity. Differentially expressed stress-responsive genes were also identified by transcriptome analysis, involved in different biological pathways during abiotic stresses. These results suggest the signaling functions of OsGSTU30 apart from its catalytic activity during abiotic stress responses and can be further exploited for improving the stress tolerance in crops.