Effects of Drought Stress and Storage on the Metabolite and Hormone Contents of Potato Tubers Expressing the Yeast Trehalose-6-phosphate Synthase 1 Gene

Comparative studies on the tuber yield and quality of commercial potato cultivars were conducted. White Lady was the wild-type (WT) accession used, and transgenic lines in this background expressing the yeast trehalose-6-phosphate synthase 1 (TPS1) gene were analysed. The plants were grown in a greenhouse under well-watered and drought stress conditions, and the metabolite and hormone contents of freshly harvested and stored tubers were tested. Periodic drought resulted in an average 50% yield loss in WT and a 30% yield loss in TPS1 plants. However, the average tuber mass remained higher in WT than in TPS1 plants. Stress elevated the abscisic acid, proline, asparagine, and phenylalanine levels and significantly affected the levels of an additional 12 compounds in tubers. In contrast to abscisic acid, the salicylic acid levels in stressed tubers were reduced. In general, storage and stress had similar effects on the metabolite and hormone concentrations in both WT and TPS1 tubers. Interestingly, storage increased the mannose, phenylalanine, and abscisic acid concentrations and decreased the salicylic acid concentrations only in the tubers of well-watered plants. TPS1 tubers had a longer dormancy period than WT tubers and exhibited alterations in the concentrations of 13 metabolites.