O s SUV 3 dual helicase functions in salinity stress tolerance by maintaining photosynthesis and antioxidant machinery in rice ( O ryza sativa L. cv. IR 64)

Summary To overcome the salinity‐induced loss of crop yield, a salinity‐tolerant trait is required. The SUV 3 helicase is involved in the regulation of RNA surveillance and turnover in mitochondria, but the helicase activity of plant SUV 3 and its role in abiotic stress tolerance have not been reported so far. Here we report that the Oryza sativa (rice) SUV 3 protein exhibits DNA and RNA helicase, and ATP ase activities. Furthermore, we report that SUV 3 is induced in rice seedlings in response to high levels of salt. Its expression, driven by a constitutive cauliflower mosaic virus 35 S promoter in IR 64 transgenic rice plants, confers salinity tolerance. The T 1 and T 2 sense transgenic lines showed tolerance to high salinity and fully matured without any loss in yields. The T 2 transgenic lines also showed tolerance to drought stress. These results suggest that the introduced trait is functional and stable in transgenic rice plants. The rice SUV 3 sense transgenic lines showed lesser lipid peroxidation, electrolyte leakage and H 2 O 2 production, along with higher activities of antioxidant enzymes under salinity stress, as compared with wild type, vector control and antisense transgenic lines. These results suggest the existence of an efficient antioxidant defence system to cope with salinity‐induced oxidative damage. Overall, this study reports that plant SUV 3 exhibits DNA and RNA helicase and ATP ase activities, and provides direct evidence of its function in imparting salinity stress tolerance without yield loss. The possible mechanism could be that O s SUV 3 helicase functions in salinity stress tolerance by improving photosynthesis and antioxidant machinery in transgenic rice.