Abstract: The present invention concerns transgenic plants producing trehalose and methods of increasing the trehalose content of plants. According to the invention, the plants of interest are transformed with the coding sequence of a gene for trehalose-6-phosphate synthase fused to a non-constitutive plant promoter, which allows for temporal, topological or stress-induced control over the expression of the gene. The invention can be used for protecting staple crop plants against drought, high salinity or temperature extremes and for improving the storage properties of harvested plants including green food stuffs, picked fruits and ornamental plants.