Genetic transformation of rice overexpressing phosphoenolpyruvate carboxykinase to increase photosynthetic efficiency and confer tolerance to salt stress

Salinity stress is one of the major worldwide obstacle for the glycophytic crop production, including rice. This phenomenon alters the cellular metabolism and causes significant crop destruction resulting in substantial reductions in yield. Through genetic engineering, it is possible to decrease the oxidative stress and increase the photosynthetic capability by using C ₃ transgenic plants that produce the C ₄ enzymes like phosphoenolpyruvate carboxykinase ( PEPCK) at a high level. In this research, we evaluate the efficiency of transgenic rice plants ( Oryza sativa L. cv. IR64) over-expressing PEPCK genes to act against salinity stress as well as increasing its photosynthetic efficiency. Rice plants overexpressing PEPCK (T ₁ generation) show tolerance to high salinity (200 mM NaCl) stress. The T ₁ transgenics showed increased levels of several biochemical factors, including ascorbate peroxidase (APX), malondialdehyde (MDA), glutathione reductase (GR) and guaiacol peroxidase (GPX) activities suggesting the existence of an effective antioxidant defense mechanism that helps the plants to deal with oxidative damage driven by salt stress. The photosynthetic parameters like chlorophyll contents, net photosynthetic rate, intercellular CO ₂ content and stomatal conductance were all considerably elevated in transgenic plants when compared with the control plants (null seggregant). It also exhibited higher agronomic characteristics than the control plant. Our findings add a preliminary conclusive evidence of PEPCK gene's potential role in regulating salt stress response and tolerance of rice plants.