Scientists Trace Complex and Juicy History of the Strawberry

In a new paper published in the Proceedings of the National Academy of Sciences, former University of Florida post-doctoral researcher Zhen Fan, now a faculty member at Zhejiang Agriculture and Forestry University in China, examined the ancient history of strawberry chromosomes.

Modern strawberries have eight sets of chromosomes, making them what scientists call “octoploids.” By comparison, most species, including humans, have two sets of chromosomes: they’re diploids.

“The modern strawberry has about four times as much DNA as the most ancient wild strawberries,” says Vance Whitaker, a UF/IFAS Professor of horticultural sciences, Fan’s former supervisor and a corresponding author of the paper. “This happened through hybridization (crossing) of up to four distinct wild species over a long time.”

“But this history and the identity of each of these ancient species have been difficult to trace because some of them went extinct long ago, and we can’t study them directly,” adds Whitaker.

In the new study, Fan found an approach to better trace that history and, in the process, he found that, before the modern strawberry began to form, various types of ancient species crossed with each other.

“This means that the genetic background of the modern strawberry is even more complex than we thought,” Whitaker says. “One reason this is important is that one day, we would like to reconstruct the modern strawberry from simpler species by making the crosses ourselves, and better understanding how the strawberry formed will help us do that. This could help us to breed better strawberry varieties in the future that are more genetically diverse and more resistant to pests and diseases.”

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