cold‐induced myo‐inositol transporter‐like gene confers tolerance to multiple abiotic stresses in transgenic tobacco plants

A full length cDNA encoding a myo‐inositol transporter‐like protein, named as MfINT‐like, was cloned from Medicago sativa subsp. falcata (herein falcata), a species with greater cold tolerance than alfalfa (M. sativa subsp. sativa). MfINT‐like is located on plasma membranes. MfINT‐like transcript was induced 2–4 h after exogenous myo‐inositol treatment, 24–96 h with cold, and 96 h by salinity. Given that myo‐inositol accumulates higher in falcata after 24 h of cold treatment, myo‐inositol is proposed to be involved in cold‐induced expression of MfINT‐like. Higher levels of myo‐inositol was observed in leaves of transgenic tobacco plants overexpressing MfINT‐like than the wild‐type but not in the roots of plants grown on myo‐inositol containing medium, suggesting that transgenic plants had higher myo‐inositol transport activity than the wild‐type. Transgenic plants survived better to freezing temperature, and had lower ion leakage and higher maximal photochemical efficiency of photosystem II (Fᵥ/Fₘ) after chilling treatment. In addition, greater plant fresh weight was observed in transgenic plants as compared with the wild‐type when plants were grown under drought or salinity stress. The results suggest that MfINT‐like mediated transport of myo‐inositol is associated with plant tolerance to abiotic stresses.