Fancy fruits: Scientists find gene that alters tomatoes' shape

Are square pears or cubic cucumbers far off? U.S. researchers have found and cloned a gene that controls the shape of tomatoes, raising the possibility that they might soon be able to drastically alter the shapes and sizes of fruits and vegetables.

The gene, dubbed SUN, is the first one found to play a significant role in the elongated shape of tomatoes, the researchers said in the March 14 issue of the journal Science.

The researchers found tomatoes were long and pointy when the gene was turned on at high levels, and round and squat when turned off.

After identifying the gene, the researchers conducted several transplants, inserting the active version of the gene into wild, round, fruit-bearing tomato plants and suppressed version into elongated tomatoes. In both cases, the addition of the gene changed the shape of the tomato plants.

"SUN doesn't tell us exactly how the fruit-shape phenotype is altered, but what we do know is that turning the gene on is very critical to result in elongated fruit," said Esther van der Knaap, the lead researcher in the study and an assistant professor of horticulture and crop science at Ohio State University in a statement issued Thursday.

"We can now move forward and ask the question: Does this same gene, or a gene that is closely related in sequence, control fruit morphology in other vegetables and fruit crops?"

The SUN gene, named for Sun 1561, a cultivated variety of tomato with an oval shape and pointy end, is the second gene known to affect the shape of plants.

The other gene, called AtIQD1, was discovered in the plant Arabidopsis thaliana, which belongs to the same family as broccoli and cabbage.

Having identified these two genes, the crop scientists hope they will lead to the discovery of others that will help them control the shape of crops such as peppers, cucumbers and gourds.

"Tomatoes are the model in this emerging field of fruit morphology studies," said van der Knaap.