CRISPR gene editing brings us sweeter tomatoes

If you like sweet tomatoes, smaller cherry tomato varieties are the way to go right now. But larger tomato varieties could soon be enhanced for sweetness with the help of CRISPR gene editing.

Jinzhe Zhang of the Chinese Academy of Agricultural Sciences in Beijing said the larger the tomato, the lower the sugar content usually is. Efforts to increase the sweetness of large varieties also had downsides, such as lower yields.

Zhang and colleagues compared different varieties to identify genetic variations that affect sweetness. They discovered two closely related genes called. SlCDPK27 and SlCDPK26 Larger varieties are more active. These genes code for proteins that reduce the levels of sugar-producing enzymes.

When the research team used CRISPR gene editing to disable these genes in a variety called Moneymaker, glucose and fructose levels in the fruit increased by up to 30% without any loss in yield. Taste tests also rated the fruit as sweeter. The only other effect is that the number of species that consumers are likely to prefer will be smaller and smaller.

“We are working with several companies to develop several commercial varieties by knocking out these genes,” Zhang says. “It's still in the early stages.”

In addition to increased sweetness, another potential benefit is that fewer tomatoes are needed to make tomato ketchup with the same sweetness level.

Gene-edited Money Maker tomatoes aren't as sweet as cherry varieties such as Sungold, but they could be made even sweeter, Zhang said. “Many important genes that control sugar are still waiting to be discovered.”

CRISPR-edited tomatoes, which contain high concentrations of a beneficial nutrient called GABA, are already on sale in Japan, the first CRISPR food to be sold, and are sometimes given as seedlings.

Tomatoes were also the first genetically modified food to be sold commercially. Called Flavr Savr, it was sold in paste form in the United States starting in 1994, but was later discontinued. Since last year, purple GM tomatoes rich in anthocyanins have become available in the United States in fruit and seedling form.

Several countries, including Japan and China, have regulations that make it easier to obtain approval for gene-edited crops compared to other forms of genetic modification, except for conventional breeding. approved by china Last year, the first gene-edited crop was created. Soybeans have high levels of oleic acid.