Pink is beautiful

Weizmann Institute scientists have discovered the gene responsible for the formation of a pink tomato, which is especially loved by the Chinese

The gene responsible for the formation of the pink and relatively sweet tomato, which is especially beloved by the people of the Far East, was recently discovered in the laboratory of Dr. Assaf Aharoni, from the Department of Plant Sciences at the Weizmann Institute of Science. The researches of Dr. Aharoni and the members of his group focus on the thin protective layer that envelops the plant, called the cuticle, and consists mainly of fatty substances such as wax. In a normal tomato, this layer also contains large amounts of anti-oxidant substances called "flavonoids", which settle on the "front line" of the plant to protect it, and color the cuticle of the tomato bright yellow. The cuticle of the mutant tomato, on the other hand, is pinkish-transparent.

In Dr. Aharoni's laboratory, a unique system was established in Israel, and one of several systems that exist in the world, which allows to quickly and efficiently identify the hundreds of substances found in a plant ("metabolites"). Through the combination of computerized methods for data processing, and additional molecular and chemical analytical methods, this approach - which developed in the last decade, and was named "metabolomics" - makes it possible to create a comprehensive profile of all the substances produced in the mutant plant, and compare it to the normal plant.

The research work - carried out by Dr. Avital Adato, Dr. Ilana Rogchev and research student Tali Mendel - showed that the differences between the pink tomato and the normal red tomato do not amount to the absence of the yellow pigment in the skin: the scientists identified about 400 M whose activity in the mutant tomato is greater or At least twice as small. The mutation has an extensive effect on the production of additional substances, mainly from the flavonoid family - both in the cuticle and in the fruit's surface. Thus, for example, it was discovered that the pink tomato contains smaller amounts of lycopene - a red pigment with strong antioxidant activity, which medical studies have shown that its consumption is linked to a lower risk of developing diseases such as cancer, heart disease and diabetes. The cuticle of the pink tomato is thinner and less flexible than the one that covers the normal tomato - due to changes in the composition of the fatty substances that make it up.

The scientists discovered that the mutation responsible for the formation of the pink tomato affects the SIMYB12 gene. This gene functions as a kind of "master switch", since the protein produced from it is responsible for the activation of many other genes. In this way, the gene regulates an entire network of genes, which determines the accumulation of the yellow pigment - as well as many other substances - in the tomato fruit. Dr. Aharoni: "Thanks to the identification of the gene, researchers will be able to use it as a marker, and use it to determine the future skin color of the fruits at a very early stage of the plant's development - even several months before flowering and fruit formation. This way it will be possible to speed up the improvement of the tomato and the development of new varieties for the Far East - a process that usually lasts over 10 years."

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