WASHINGTON (Xinhua): U.S. scientists have identified a gene that controls the shape of tomatoes, a discovery that could help unravel the mystery behind the huge morphological differences among edible fruits and vegetables.

The discovery was reported, as the cover article, in the March 14 issue of the journal Science.

The gene, dubbed SUN, is only the second ever found to play a significant role in the elongated shape of various tomato varieties, said Esther van der Knaap, lead researcher in the study at Ohio State University.

As one of the most diverse vegetable crops in terms of shape and size variations, tomatoes have evolved from a very small, round wild ancestor into the wide array of cultivated varieties -- some large and segmented, some pear-shaped, some oval, some resembling chili peppers -- available through most seed catalogs and for sale in supermarkets.

However, very little is known about the genetic basis for such transformations in tomatoes, and virtually nothing has been discerned about morphological changes in other fruits and vegetables.

"Tomatoes are the model in this emerging field of fruit morphology studies," van der Knaap said. "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." "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, cucumbers and gourds," she added.