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German-Israeli research team discovers DNA fragments in wild tomatoes which
could allow the development of better cultured tomatoes, 27 2006.

Tomatoes are good for you. They strengthen the immune system and can
prevent heart and circulatory disease. Now, researchers from the Max Planck
Institute of Molecular Plant Physiology, in co-operation with Israeli
scientists, have identified DNA fragments in tomatoes that make their
contents both healthy and tasty. The researchers crossed wild tomatoes with
cultured ones, then investigated the contents and genetic make-up of the
hybrid. The results could allow tomato growers to use wild tomatoes to
produce cultured tomatoes with the characteristics they desire (Nature
Biotechnology, March 12, 2006).

Tomatoes are a major nutrient for humans. In 2004, 120,000 tonnes of
tomatoes were harvested worldwide - and every year this number increases.
Numerous medical studies have shown the health value of tomatoes. Lycopen,
the pigment that makes tomatoes red, can for example prevent heart disease.
Tomatoes furthermore contain a lot of vitamins C and E, indispensable for
human nourishment. But after centuries of cultivation for shape, colour, and
other useful qualities, our cultured tomatoes today are of small genetic
diversity, in comparison with wild types. This has affected the taste and
health value of the fruits.

To cultivate tomato strains with particular characteristics, researchers
have to increase the genetic diversity of cultured tomatoes. This can be
done either by cross-breeding them with wild tomatoes, or changing their
genetic make-up technologically. Scientists from the Max Planck Institute
for Molecular Plant Physiology in Golm, and their Israeli colleagues at
Hebrew University in Jerusalem, chose the second option. They investigated
strains of tomatoes created from the crossing of cultured and wild types.
Their goal was to identify the biochemical composition of fruits and
determine which factors control their development. The German-Israeli
research team used a method of analysis developed at the Max Planck
Institute for Molecular Plant Physiology. The technique - a combination of
mass spectrometry and gas chromatography - analyzes the composition of
biological samples. It can be used to quickly and simultaneously look into a
fruit?s amino acids, organic acids, sugar and vitamins.

Dr. Alisdair Fernie, head of the Institute?s "Central Metabolism" research
group, discovered that there were 880 variations in the content composition
of descendants produced by crossing cultured tomatoes and wild tomatoes. "On
one hand, we measured higher amounts of essential amino acids and vitamins,
on the other hand the fruits showed an altered combination of various sugars
and organic acids," Fernie says. These contents have a great influence on
the taste of tomatoes.

The scientists used molecular biological methods to identify parts of the
tomato genomes responsible for biochemical changes. The researchers?
findings could make it possible in the future to cross-breed wild tomatoes
with cultured tomatoes in a targeted way to make them more nutritious.

[www.mpg.de]

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