The present invention relates to plant cells and plants, which are genetically modified, whereby the genetic modification leads to an alteration of storage compound deposition in Beta vulgaris tap-root, such as sugar beet tap-root or fodder beet tap-root. By the alteration the tap-root of the plants accumulates starch in comparison with the corresponding wild type plant tap-root. In addition, the present invention concerns means and methods for the manufacture of such plant cells and plants. The present invention also concerns the starches synthesised from the tap-root of these plant, methods for manufacturing these starch. Furthermore, the present invention also relates to nucleic acids, coding the genes involved in the synthesis of starch, vectors, host cells, plant cells, and plants containing such nucleic acid molecules.