What? Scientists have found the secret to keeping tomatoes firm and tasty!

Produced by: Science Popularization China

Author: Shi Wuyao (PhD in Biology)

Producer: China Science Expo

Tomato is a common vegetable in our daily life. It is rich in vitamin C, multiple minerals and trace elements, and is sweet and sour, so it is loved by people. Tomatoes can be eaten directly or cooked, and can also be used to make tomato sauce.

Delicious tomatoes bring people a taste enjoyment. And if the tomatoes can be stored for a long time without becoming soft while maintaining their delicious taste, it will be icing on the cake. In September 2023, Chinese scientists found the secret to making tomatoes firm and delicious!

tomato

(Photo source: veer photo gallery)

Let’s go! Find the secret to making tomatoes delicious and resistant to stress

On September 18, 2023, Chinese scientists published an article on the research of tomato genome in the journal Nature Plants. The study found that by modifying the tomato genome, tomatoes with both firmness and deliciousness can be obtained!

The research results were published in the journal Nature Plants

(Image source: Nature Plants magazine)

Tomatoes can be eaten fresh or processed. Fresh tomatoes sold in supermarkets are usually round and easily soften and crushed, so they are mainly picked by hand when the fruits are ripe.

Tomatoes used for processing and consumption are usually egg-shaped and very firm. They can be harvested mechanically after ripening and thrown directly into the truck without worrying about the fruit being damaged. Therefore, the harvesting efficiency is greatly improved and the cost of manual harvesting is saved.

However, the egg-shaped tomato is not as delicious as the round fresh-eating tomato, and its acceptance is relatively low when eaten directly. Therefore, scientists start from the tomato genome, hoping to find the secret to make tomatoes delicious and high in pressure resistance!

In order to explore the specific location of the genes that control tomato hardness, scientists hybridized round and egg-shaped tomatoes, sowed the resulting tomato seeds on a large scale, and conducted batch studies on the resulting fruits.

Finally, scientists found that the shape of tomatoes is closely related to the site mutation of the FS8.1 gene located in its heterochromatin region. The FS8.1 gene mainly controls the growth of fruits and inhibits the proliferation of ovary wall cells. Therefore, when the FS8.1 gene is normal, the ovary will grow evenly in all directions, and the tomatoes that grow are round.

However, when the FS8.1 gene site mutates, it loses its inhibitory effect, and the ovary wall cells of the tomato will over-proliferate, causing the tomato to grow excessively in a certain direction, eventually forming an egg-shaped tomato.

The mutation of the FS8.1 gene locus does not affect the content of soluble sugars, organic acids and lycopene in tomatoes, and therefore does not affect the taste of tomatoes , but only affects the shape and firmness of tomatoes. Based on this, scientists knocked out the FS8.1 gene in tomatoes, and eventually made tomatoes grow into egg shapes. The taste was not affected, but the stress resistance was significantly enhanced.

FS8.1 gene controls tomato shape

(Image source: Reference [1])

Not only hardness, genes can determine much more!

In fact, gene editing can do far more than determine a tomato’s stress tolerance; it can also make it more nutritious.

Vitamin D is an essential nutrient for the human body and is closely related to human growth and development. By using gene editing technology to transform tomatoes, they can be turned into super tomatoes rich in vitamin D.

Under light conditions, ultraviolet rays can promote the synthesis of 7-dehydrocholesterol and convert it into vitamin D3. At the same time, tomatoes also have reductases that inhibit its conversion into vitamin D. Therefore, scientists use gene editing technology to knock out specific genes that control the synthesis of reductases, thereby limiting the synthesis of reductases in tomatoes and achieving a cumulative increase in the content of 7-dehydrocholesterol.

Then, the scientists exposed the tomatoes to sunlight for sufficient ultraviolet radiation. Finally, the vitamin D3 content in the modified tomatoes was measured and it was found that the vitamin D3 in one tomato was equivalent to that in two eggs . The modified tomatoes had no difference in taste and growth cycle compared to the unmodified tomatoes. It can be seen that eating one tomato a day can achieve sufficient vitamin D supplementation.

Vitamin D

(Photo source: veer photo gallery)

Gene editing makes tomatoes look better

When we choose vegetables and fruits, we should not only choose delicious ones but also good-looking ones. Good-looking tomatoes not only bring visual enjoyment to people, but also stimulate people's desire to buy. The most common color of tomatoes sold on the market is red. Studies have shown that by modifying the tomato genome, people can create tomatoes with more diverse colors.

The color of tomatoes is determined by the color of the skin and flesh . The depth of the color is closely related to the content of lycopene, chlorophyll, flavonoids and other pigments in the fruit. The redder the tomato, the higher the content of lycopene and flavonoids, and the lower the chlorophyll content.

Based on this discovery, scientists used gene editing technology to knock out the genes that control the synthesis of lycopene and flavonoid pigments, as well as the genes that control chlorophyll degradation, preventing them from being expressed.

Finally, the fruit grown is green because the red pigment cannot be synthesized and the green pigment cannot be degraded. After that, this tomato is hybridized with a red tomato, and the genome of the fruit is screened to obtain fruits of various colors such as red, orange, pink, green, and brown. This technology can also be extended to horticultural crops to create more colorful and beautiful plants.

Multi-colored tomatoes

(Photo source: veer photo gallery)

Conclusion

Whether it is animals or plants, genes are the key to controlling the expression of individual biological traits. With the advancement of science and technology, scientists have been trying to use gene editing technology to change the traits of various fruits and vegetables, including tomatoes, so that they can fully meet the needs of human life.

I believe that in the near future, scientists will create a variety of novel and nutritious vegetables and fruits, thereby promoting the development of botanical research and related industries!

References:

[1] Zhu, Q., Deng, L., Chen, J. et al. Redesigning the tomato fruit shape for mechanized production. Nat. Plants (2023).

[2] Li, J., Scarano, A., Gonzalez, NM et al. Biofortified tomatoes provide a new route to vitamin D sufficiency. Nat. Plants 8, 611–616 (2022).

[3] Ana Arruabarrena, Joanna Lado, Matías González-Arcos, Sabina Vidal. Targeted disruption of tomato chromoplast-specific lycopene β-cyclase (CYC-B) gene promotes early accumulation of lycopene in fruits and enhanced postharvest cold tolerance. Plant Biotechnology Journal(2023), pp. 1–3

[4] Yang. TX; Ali. M; Lin. LH, Recoloring tomato fruit by CRISPR/Cas9-mediated multiplex gene editing. HORTICULTURE RESEARCH, Volume10 Issue1.