Overexpression of LmgshF from Listeria monocytogenes in Indica Rice Confers Salt Stress Tolerance

Abstract

Glutathione (γ-glutamylcysteinylglycine; GSH), is a multi-functional tri-peptide antioxidant, a key agent in defense against abiotic and biotic stress. A novel bi-functional enzyme LmgshF identified from Listeria monocytogenes, had developed transgenic rice (Oryza sativa L.) plants under the control of cauliflower mosaic virus (CaMV) 35S promoter in indica rice cultivar NAUR-1. LmgshF gene was stably inherited and expressed in T₂ plants, as indicated by the results of PCR, ELISA, RT-PCR and qRT-PCR (quantitative real time PCR) analyses. An average expression of LmgshF was 3.03 μg/mg of total soluble protein in leaf extracts of transgenic plants. QRT-PCR analysis of LmgshF showed 5.83- and 6.07-fold higher in gshF-5-7 and gshF-5-8 plants respectively, at 200 mM NaCl treatment in transgenic rice. Under salt stress conditions, transgenic plants possessed higher level of glutathione, proline, photosynthetic pigments and antioxidant enzyme activities, than that of its wild type (WT) plants. It showed better germination, displays long roots, shoots and heavier fresh weights and survival percentage compared to its wild type under salt stress conditions. HPLC (High Performance Liquid Chromatography) analysis showed that the glutathione content was 14-fold higher in transgenic rice at 200 mM NaCl treatment. Transgenic rice plants showed enhanced levels of glutathione to counter the adverse effects of salinity and resulted in improved salt stress tolerance in rice.