Effect of carbon source and sucrose concentration on growth and hexose accumulation of grape berries cultured in vitro

Using in vitro culture of isolated small berries of Vitis vinifera L. cv. S ultana, it was possible to study the effect of different carbon sources and sucrose concentration on fruit growth, hexose accumulation and soluble inv ertase activity during the first stage of berry development by eliminating the source tissue. Berries cultured in vitro lack stage III of berry develo pment which is characterised by massive accumulation of water and sugars, a nd thereby berries reached only 30% of the weight of those grown in the pla nt. Sucrose and glucose were both good carbon sources for berry growth, whi le fructose was not as good. Berry growth, hexose accumulation and invertas e activity increased as sucrose concentration increased up to 15% in the me dium. Furthermore, the onset of hexose accumulation in cultured berries dep ended on the concentration of sucrose in the medium, starting earlier at hi gher concentrations.