Genetic engineering of salt and drought tolerance with yeast regulatory genes

Two yeast regulatory genes involved in stress tolerance, HAL1 and TPS1, have been expressed in transgenic plants. In yeast cells, HAL1 modulates cation transport and TPS1 affects sugar metabolism and indirectly stress genes. In addition, TPS1 encodes trehalose-6-P synthase and is involved in trehalose synthesis. Transgenic plants expressing HAL1 exhibited an improved salt tolerance under 'in vitro' culture conditions. In the case of TPS1, transgenic plants exhibited several morphological alterations and enhanced salt and drought tolerance. No significant trehalose accumulation was observed in TPS1-expressing plants. The results can be explained by activation of endogenous plant defence genes and, in the case of TPS1, of other plant responses triggered by the yeast regulatory genes. (C) 1999 Elsevier Science B.V. All rights reserved.