Original Research Paper: Ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid) biosynthetic genes (ect ABC) derived from the halophilic bacterium Halomonas elongata were introduced into tomato (Lycopersicon esculentum) using an Agrobacterium-mediated gene-delivery system. Stable integration of the ectoine genes into the regenerated plant genomes was confirmed by PCR and Southern blot analyses. Expression of these genes was detected in the transgenic tomato plants by Northern blot analysis. The transgenic plants exhibited the normal growth characteristics of the non-transgenic plants. The concentration of ectoine increased with increasing salinity, and the increase was higher in the roots than in the leaves. The present data indicates that the turgor values of the ectoine transgenic tomato lines increased with increasing salt concentration. The data suggests that the accumulation of ectoine in transgenic tomato plants contributed to the maintenance of osmotic potential of the cells
