Velcheva, M., Department of Genetics, Agricultural University, Plovdiv, Bulgaria, Bulgaria
Faltin, Z., The Dept. of Fruit Tree Sciences, Agricultural Research Organization, Volcani Ctr., P.O. Box 6, 50250 B., Israel
Flaishman, M., The Dept. of Fruit Tree Sciences, Agricultural Research Organization, Volcani Ctr., P.O. Box 6, 50250 B., Israel
Eshdat, Y., The Dept. of Fruit Tree Sciences, Agricultural Research Organization, Volcani Ctr., P.O. Box 6, 50250 B., Israel
Perl, A., The Dept. of Fruit Tree Sciences, Agricultural Research Organization, Volcani Ctr., P.O. Box 6, 50250 B., Israel

Two systems for Agrobacterium transformation and subsequent plant regeneration, on solidified media and in liquid culture, were developed and employed on different commercial tomato cultivars. The efficiencies of transformation and regeneration were studied. After selection on solid media following transformation, approximately one-quarter of the regenerated plants were non-transformed regenerants (escapes). On the other hand, an improved and highly efficient system for regeneration of transformed explants was developed while using liquid cultures. This is due not only to the better distribution of the selective agent in the liquid medium, but also to differences in the origin of shoot initiation between the solidified and the liquid media. Optimal Agrobacterium-mediated transformation, shoot regeneration and selection of transformed tomato plants were demonstrated in the present study by using, for the first time, liquid cultures. © 2004 Elsevier Ireland Ltd. All rights reserved.