In addition to being among his most vibrant and celebrated works, Vincent van Gogh's series of sunflower paintings also depict a mutation whose genetic basis has, until now, been a mystery. In a study published in PLoS Genetics, a team of University of Georgia scientists reveal the mutation behind the distinctive, thick bands of yellow "double flowers" that the post-Impressionist artist painted more than 100 years ago.
The most common sunflower trait is a composite flower head that contains a single whorl of large, flattened, yellow ray florets on the outer perimeter and hundreds to over a thousand individual, tubular, disc florets that can produce seeds. The double-flowered mutants that van Gogh depicted in many of his paintings, on the other hand, have multiple bands of yellow florets and a much smaller proportion of internal disc florets.
To understand the genetic basis of this difference, senior author John Burke, professor of plant biology in the UGA Franklin College of Arts and Sciences, and his colleagues began by using the same plant crossing techniques that Gregor Mendel, a 19th century contemporary of van Gogh, used to lay the foundation of modern genetics. The scientists crossed the common, or "wild type", variety of sunflower with the double-flowered variety, and their initial findings suggested that a single, dominant gene was responsible for creating the double-flowered mutation. Subsequent crosses of the offspring revealed that a second mutation, which is recessive to both the double-flowered mutation and the wild-type version of the gene, results in a third flower type that is intermediate in form, being elongated and yellow, but tubular and containing the reproductive structures of the interior florets.
The scientists identified the responsible gene and sequenced it to show that in the double-flowered mutation, the portion of the gene that functions as an on/off switch is disrupted, so that the instructions
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