Scientists at the Leibniz Institute for Plant Biochemistry (IPB) in
Halle have used genetic engineeringmethods to produce purple tomatoes
using dye from beetroot.

The scientists smuggled the genesfor the biosynthesis of betanin into
the plants and activated them in the ripening fruits. Betanin is not
originally formed in tomatoes and comes from beetroot as a natural food
coloring. Like many dyes, betanin has a strong antioxidant effect. The
purple fruits produced could also serve as a source of betanin for food
coloring. First attempts to color yogurt and lemonade with tomato
betanin were promising.

The study is aimed towards further development of genetic engineering
methods, which can be analyzed with the production of a clearly visible
dye. In the case of betanin, planning and readjustment was carried out
for a long time in order to achieve the desired synthesis performance in
tomatoes. The Halle-based scientists not only brought three biosynthesis
genes required for betanin production into the tomato plants but also
several genetic switches with which the genes introduced could only be
activated in the fruit and all of them at the same time, exactly at
ripening time. However, betanin production in the fruits was initially
low and the research team had to introduce a fourth gene, that the
biosynthesis of the dye could be sustainably increased. The result is
deep purple tomatoes that contain even more betanin than beetroot.

Lila Tomaten durch Farbstoff aus der Roten Beete: Leibniz-Institut f??r
Pflanzenbiochemie (ipb-halle.de)
[www.ipb-halle.de]