'Plant shape' gene discovered

2008-03-15 10:41

Washington - US scientists have discovered and cloned a gene that controls the shape of tomatoes, a find which could help unravel the morphological mysteries of the plant world, a study released on Thursday said.

The gene known as SUN, the second ever found to play a key role in the formation of elongated tomato varieties, could provide vital new insight into how edible plants develop, said Esther van der Knaap, lead researcher of the study published in the journal Science.

Tomatoes, among the most varied crops in terms of size and shape, evolved from a small, round ancestral wild fruit to the many varieties grown today. But little is known about the genetic principles for such transformations in tomatoes or other fruits and vegetables.

"Tomatoes are the model in this emerging field of fruit morphology studies," said van der Knaap, an assistant professor of horticulture and crop science at Ohio State University.

"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," she added.

"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 also said that SUN, which takes its name from the oval shaped and pointy "SUN 1642" tomato variety in which the gene was found, does not show exactly how the fruit-shape phenotype gets changed.

"But what we do know is that turning the gene on is very critical to result in elongated fruit," she said.

The objective now, van ker Knaap said, is to determine whether the same gene, or one closely related, controls morphology in other fruit and vegetable crops.

The SUN gene affects fruit shape after pollination and fertilisation, whereas the only other fruit-shape gene previously identified - known as OVATE - affects the shape of fruit before flowering, the report said.

- AFP