Arabidopsis plants constitutively overexpressing a myo-inositol 1-phosphate synthase gene (SaINO1) from the halophyte smooth cordgrass exhibits enhanced level of tolerance to salt stress

Salinity is one of the most important environmental constraints limiting agricultural productivity. Considering the importance of the accumulation of osmolytes, myo-inositol in particular, in halophytic plant's adaptive response to salinity, an effort was made to overexpress the SaINO1 gene from the grass halophyte Spartina alterniflora encoding myo-inositol 1-phosphate synthase (MIPS) in Arabidopsis thaliana. We demonstrated that SaINO1 is a stress-responsive gene and its constitutive over expression in Arabidopsis provides significantly improved tolerance to salt stress during germination and seedling growth and development. The transgenics retained more chlorophyll and carotenoid by protecting the photosystem II. The low level of stress-induced cellular damage in the transgenics was clearly evident by lower accumulation of proline in comparison to WT. Our results indicated that possible overaccumulation of MIPS enzyme in the cytosol protected the transgenic Arabidopsis plants overexpressing SaINO1 from the toxic effect of Na+ under salt stress by reducing cellular damage and chlorophyll loss.

► Arabidopsis plants overexpressing SaINO1 showed enhanced tolerance to salt stress.
► SaINO1-Arabidopsis transgenics germinated and grew better than WT under 150 mM NaCl.
► SaINO1-Arabidopsis plants accumulated less proline than WT under salt stress.
► SaINO1-Arabidopsis plants protected their photosystem II from stress-induced damage.
► The transgenics had higher chlorophyll and carotenoid than WT under salt stress.