Ellen Phiddian
Cosmos science journalist
Researchers have grown a genetically modified tomato with 30% more sugar – without sacrificing size.
Over centuries of domestication, tomatoes have become 10 to 100 times larger than their wild counterparts. But these big tomatoes have lost their sweetness on the way.
The first commercially available genetically modified crop was a tomato, released in the USA in 1994 – although it proved financially unviable.
Other genetically modified varieties have followed, such as a purple tomato approved by the US FDA in 2022.
But until now, researchers haven’t found a way to keep both the size and the sugar content of the humble Solanum lycopersicum.
A study published in Nature shows that removing 2 key genes can increase the fructose and glucose of a tomato, while maintaining yield and weight of each fruit.
“Sugars are powerful regulators of organ growth and development, and are intertwined with fruit weight in a complex and dynamic relationship,” write the researchers in their paper.
The researchers used a genome-wide association study to analyse the DNA of both cultivated and wild tomatoes, looking for genes related to sugar production.
They isolated 2 which both act as “brakes”: they regulate, and lower, the number of sugar-producing enzymes.
The team then used CRISPR to remove these genes from cultivated tomato plants.
The resulting plants made the same numbers and size of tomatoes, but they contained up to 30% more fructose and sucrose.
The genetically modified tomatoes did produce fewer, and lighter, seeds. But these seeds were healthy, and germinated normally.
In their paper, the researchers write that their work “provides a possible solution for improving sugar content without reduction in fruit yield for modern commercial varieties, which are preferred by both consumers and producers”.
“CRISPR-edited ‘sweetness-promoting’ tomatoes may be available to consumers in the near future,” they conclude.
