Over Expression of the Carbonic Anhydrase Gene Confers Salinity Tolerance with Improved Yield in Rice

Background: Abiotic and biotic stresses impact agricultural productivity. Rice being the stable food of India; requires more scientific intervention to boost productivity. Methods: Cloning and transformation of carbonic anhydrase (CA) gene in IR64 rice, molecular analysis of T1 transgenic CA rice plants, salinity tolerance index, leaf disk senescence assay, chlorophyll content, biochemical analysis of antioxidant activities of marker-free CA transgenic lines and measurement of photosynthetic activities and agronomic characteristics of CA transgenic plants were conducted. Result: We have raised two (2) lines of marker free CA overexpressing transgenic rice (Oryza sativa L. cv. IR64) plants. The overexpression of CA driven by CaMV35S promoter in transgenic rice confers high salinity (200 mM NaCl) stress tolerance in the rice. Photosynthetic characteristics such as net photosynthetic rate (PN), stomatal conductance (gs), intercellular CO2 (Ci), as well as chlorophyll (Chl) contents were significantly (22-31%) higher in transgenic lines under salinity stress as compared to control plants. Ascorbate peroxidase (APX), superoxide dismutase (SOD), glutathione reductase (GR) and guaiacol peroxidase (GPX) were significantly higher (21-37%) in transgenics as compared with VC and WT plants. Overall, the present research is focused to develop marker free CA overexpressing transgenic lines for better tolerance against salinity stress, higher photosynthesis and better productivity.