While studying sunflower genetics, Burke and colleagues have also found a clue to the history of sunflower domestication that may help answer the question of whether van Gogh’s favorite flower was domesticated on more than one occasion. Some researchers had suggested, for instance, that southern Mexico was the site of an independent domestication event.

In their search for evidence of the hypothesized Mexican origin, Burke and colleagues investigated patterns of gene-sequence variation in the chloroplasts (plant cells responsible for photosynthesis) of wild and cultivated sunflowers. Because the DNA of this specialized subcellular structure is handed down from a maternal plant to its seed, its examination is useful for determining lineage. Burke’s team found that all of the cultivars they surveyed harbored a single chloroplast type, even when there were many different forms present across the geographic range of wild sunflowers.

“Our results suggest a single North American origin of extant domesticated sunflowers,” said David Wills, a graduate student in Burke’s lab. “Of course, we can’t rule out the possibility of a Mexican domestication event, the descendant of which ultimately went extinct.”

While sunflowers both wild and domesticated will continue to show their shining faces and perhaps inspire other painters, regardless of the plants’ ancestry, they will certainly inspire scientists. Burke is confident that his lab’s research will make contributions both to the basic and applied sides of plant biology.