Apple Columnar GeneMdDMR6Increases the Salt Stress Tolerance in Transgenic Tobacco Seedling and Apple Calli

Recent studies have shown that theMdDMR6is a key gene for the control of columnar growing habit. However, there has been no research report on the function of theMdDMR6gene. In the present study, the columnar apple shoot cultures exhibited better tolerance than that of the standard apple shoot cultures under the salt stress. The expression ofMdDMR6was remarkably induced by the salt stress. Subsequently, theMdDMR6was transferred into tobacco and apple calli via the Agrobacterium-mediated approach. Functional analysis showed that the overexpressing transgenic tobacco and apple calli displayed salt tolerance and ABA-insensitive phenotype through physiological and biochemical analysis. TheMdDMR6overexpression activated the transcript levels of several genes involved in the ABA-dependent stress genes under the salt condition. These results suggest that theMdDMR6would increase the plant tolerance to the salt stress via activating or interacting other protein to indirectly activate ABA-dependent pathways.