Heterologously Expressing a Wheat CI Small Heat Shock Protein Gene Enhances the Salinity Tolerance of Arabidopsis thaliana

The productivity of wheat, like that of most crop species, is adversely affected by soil salinity, so the identification of genes contributing to the salinity tolerance is an important priority for crop improvement. This study focuses on TaHSP17.6, a gene which encodes a salt and abcisic acid (ABA) inducible class I small molecular heat shock protein. Its transcription level was higher in a salinity tolerant wheat cultivar SR3 than in its less tolerant, but closely related cultivar JN177. The constitutive expression of TaHSP17.6 in Arabidopsis thaliana boosted the plants' tolerance to salt stress and decreased their sensitivity to exogenously supplied ABA. Compared to wild type plants, the transgenic plants, when challenged with either salinity or ABA, developed a greater number of lateral roots, and their leaves accumulated more proline and have a higher activity of the antioxidant enzyme peroxidase. The transgenic leaves were superior to wild type ones with respect to their ability to maintain their hydration when detached from the plant. The product of TaHSP17.6 is proposed to contribute to the tolerance of osmotic and oxidative stress in an ABA-dependent manner. TaHSP17.6 is proposed as a candidate gene for engineering salinity tolerance in wheat.