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The secret of seedless grapes

Léo Ramos Chaves Temporary silencing of a certain gene results in residual seeds in the sultana grapeLéo Ramos Chaves

Known in the US and Brazil by the name of Thompson Seedless, sultana grapes are the result of a natural mutation that left them seedless. Thought to have originated in the region between Turkey and Greece, they are typically eaten fresh or as raisins, and their wine is not seen as high quality. A team of Brazilian researchers, led by molecular biologist Luís Fernando Revers from the EMBRAPA Grape and Wine division in Bento Gonçalves, Rio Grande do Sul, confirmed the molecular mechanism that causes these grapes to be seedless (Journal of Experimental Botany, March 28). They compared the activation pattern of the VviAGL11 gene during development of a seeded grape (the Chardonnay, used to make wine) and the sultana grape. For years, it has been suspected that this gene is involved in seed formation, but the hypothesis has not yet been proven. Revers and his team found that in Chardonnay grapes, VviAGL11 is expressed at moments crucial to the formation of the shell that covers the seeds. In the sultana grape, the gene is simply not activated at this stage, resulting in residual seeds—essentially seedless grapes. Determining the role of this gene could be useful for manipulating seed formation in a variety of plants. “The hope is to transform this knowledge into a tool, so that DNA tests can tell us whether the grapes will have seeds or not, even before the fruit is produced,” says the molecular biologist. According to the researcher, this could be utilized to accelerate the development of new cultivars.