Discover the gene that forms the fruit shape

The gene, SUN, is only the second gene discovered to play an important role in forming the long form of many different tomato varieties, according to Esther van der Knaap, principal researcher of the project and a lecturer. about crop science and fruits at the Ohio University Agricultural Research and Development Center (OARDC) in Wooster.

The discovery is covered by the cover page on the March 14 edition of Science .

One of the most diverse plants in size and shape, tomatoes evolved from a small, round wild plant into a variety of plants - some large, pear-shaped, umbrella-shaped plants. -van, a chili-like image - is easy to find in supermarkets or seed shops.

Van der Knaap pointed out that: 'Tomato is the subject of research in the field of fruit morphology. We are trying to understand which genes cause a tremendous increase in fruit size and fruit diversity when tomatoes are domesticated. Once we have identified all the genes selected in this process, we can sequence information about how domestication forms the shape of tomatoes - and gain more knowledge about what governs. shapes of other diverse crops such as chili, cucumber and gourd, pumpkin. "

One of the first pieces of Van der Knaap obtained during the puzzle solving of fruit development is the SUN gene, named from the ' Sun 1642 ' plant - an oval-shaped tomato with its head sharp. This gene turned out to be very popular in genetically long varieties like chili ' Howard German '.

'After examining the entire tomato gene emulsion, we noticed some long fruit-shaped varieties. Through genetic analysis, we limit the gene region that governs this fruit shape and eventually limit it to a smaller section so that it can be sequenced and find the gene present at that location. '

Van der Knaap continued: 'By doing so, we identified an important candidate gene that appeared at very high frequencies in long-range tomato varieties, while the gene did not work in the fruit round. And after we reaffirmed this recognition in other varieties, we found that this gene is almost always present in long-shaped fruit varieties. '

Once the SUN gene has been identified, the next step includes proving whether the gene actually causes changes in fruit shape. To do that, Van der Knaap and his team conducted many transplant experiments. When the SUN gene was introduced into wild round fruit trees, these plants gave birth to exceptionally long fruits. And when the gene is removed from the long fruit trees, they produce round fruits like wild tomatoes.

'SUN does not tell us exactly how the shape has changed, but we also know that activating this gene has a very important role in creating long-form fruit. We can continue to study and ask the question: Is this gene or a closely related gene dominant in other plants and vegetables? '

One more thing that the scientific team discovered was that gi en SUN coded a component of the IQ67 group that produced plant proteins called IQD12 , which itself lacked enough tomatoes to lengthen instead of round transplant experiment.

IQD12 belongs to a protein family and the discovery of this family is quite new in the biological world, so new that only IQD12 is the second IQ67 protein region to work in the identified plant. The other is AtIQD1, found in Arabidopsis thaliana, the same family of cabbage and broccoli.

Van der Knaap explained: 'Unlike AtIQD1, SUN does not seem to affect the amount of glucosinolate in tomatoes, because this energy metabolism does not form in Solanaceous plants (including tomatoes, sweet peppers, coffee and other Other popular crops). But there is a link between these two genes, that is, they can regulate the amount of tryptophan in plants. Therefore, SUN can tell us more about the whole process of diversification in fruits and plants, possibly through its effect on plant hormones and / or level 2 metabolism. . '

During the process of identifying and cloning the SUN, Van der Knaap and the team were able to trace the source of this gene and the process it settled in tomatoes.

One of the other unique features of the SUN gene is its effect on fruit shape after pollination and fertilization, with the most marked morphological changes in fruit development within 5 days after flowering. The only fruit shaped gene discovered before OVATE, discovered by Cornell University plant breeder Steven Tanksley - affects the future shape of the fruit before flowering, at the beginning of the period of stigma.