Scientists Discover Genes For Bigger Tomatoes and Eggplants

Researchers led by teams at Johns Hopkins University and Cold Spring Harbor Laboratory have discovered new genes in tomatoes and eggplants that control how many seed cavities (locules) will grow.

The research is part of a project to map the complete genomes of 22 crops in the nightshade genus, which include tomatoes, potatoes, and eggplants. The researchers compared the genome maps and traced how the genes evolved. They found that in the past, more than half had been duplicated. The team at the Boyce Thomson Institute used CRISPR-Cas9 gene editing technology to tweak one or both duplicates of a gene, and collaborators at Cold Spring Harbor grew the engineered plants to see how the tweaks changed the mature plants.

The genetic duplicates called paralogs ended up being important for determining traits such as flowering time, fruit size, and fruit shapes. Turning off both copies of the CLV3 gene paralogs in the forest nightshade native to Australia, for example, resulted in plants that are not viable to sell as produce in grocery stores. However, editing one copy of CLV3 led to larger fruits. In the African eggplant, a species grown across Africa and in Brazil, the researchers identified the gene SaetSCPL25-like that controls the number of seed cavities, or locules, inside the fruit. When they edited the SaetSCPL25-like genes in the tomato plant, the researchers found they could grow tomatoes with more locules. The more numerous the locules, the bigger the tomato.

"This work shows the importance of studying many species together," Schatz said. "We leveraged decades of work in tomato genetics to rapidly advance African eggplants, and along the way we found entirely new genes in African eggplants that reciprocally advance tomatoes. We call this 'pan-genetics,' and it opens endless opportunities to bring many new fruits, foods, and flavors to dinner plates around the world."

For more details, read the news article in Johns Hopkins University Hub.