Gene that gives tomatoes elongated shape identified

Washington, June 28 : Ever wondered what gives fruits and vegetables different shapes and sizes? Well, so far as tomatoes are concerned, crop scientists at Ohio State University have found that a gene called SUN plays a significant role in the elongated shape of various varieties of the fruit.

Esther van der Knaap, an assistant professor of horticulture and crop science who led the National Science Foundation-funded study, says that the SUN gene is only the second ever found to control the shape of tomatoes.

She says that this discovery may be helpful for researchers trying to discern what causes huge morphological differences among edible fruits and vegetables, as well as provide insights into mechanisms of plant development.

"We are trying to understand what kind of genes caused the enormous increase in fruit size and variation in fruit shape as tomatoes were domesticated," Live Science quoted her as saying.

"Once we know all the genes that were selected during that process, we will be able to piece together how domestication shaped the tomato fruit - and gain a better understanding of what controls the shape of other very diverse crops, such as peppers and the cucumber and squash family," she added.

She revealed that her team used a unique software program she herself developed, called the "Tomato Analyzer", to analyse the shapes of elongated tomatoes, and the genetic variations accounting for such elongations.

"After looking at the entire collection of tomatoes we could find, we noticed that there were some varieties that had very elongated fruit shape. By genetic analysis, we narrowed down the region of the genome that controls this very elongated fruit shape, and eventually narrowed down that region to a smaller section that we could sequence to find what kind of genes were present at that location," she said.

"In doing that, we identified one key candidate gene that was turned on at high levels in the tomato varieties carrying the elongated fruit type, while the gene was turned off in round fruit," she added.

Having identified SUN, the researchers decided to determine whether the gene was actually responsible for causing changes in fruit shape, and conducted several plant-transformation experiments for the purpose.

The researchers first introduced the gene into wild round fruit-bearing tomato plants, and ended up producing extremely elongated fruit.

When they "knocked out" the gene of elongated fruit-bearing plants, they produced round fruit similar to the wild tomatoes.

When asked if her lab could make small round cucumbers, van der Knaap said: "I'm not sure. But they would certainly look nice in a salad."

ANI