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Study slices and dices the complex history of the modern strawberry
If you eat fruits or vegetables, how often do you think about their history? Former University of Florida post-doctoral researcher Zhen Fan did, as he traced the strawberry back over centuries.
In a new paper published in the Proceedings of the National Academy of Sciences, Fan, now a faculty member at Zhejiang Agriculture and Forestry University in China, examined the ancient origins of strawberry 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,' said 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,' said Whitaker, a strawberry breeder at the Gulf Coast Research and Education Center.
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 said.
'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,' Whitaker said. 'This could help us to breed better strawberry varieties in the future that are more genetically diverse and more resistant to pests and diseases.'
Strawberry is kind of the opposite of a 'purebred,' Whitaker said.
'With multiple species in its background the strawberry is fun and challenging to work with for a breeder like me,' he said.
Doug and Pam Soltis, distinguished professors at the Florida Museum of Natural History and co-authors on the study, put the research into an interesting historical perspective.
'Strawberry might be the opposite of a purebred, but it is typical of the complexities we see in natural populations of plants — complicated evolutionary histories of repeated hybridization, introgression and genome doubling,' Doug Soltis said. 'Solving these problems involves dedicated research — each is a story of intrigue and investigation that puts solving any murder mystery to shame.'
Added Pam Soltis: 'The methods developed for reconstructing the evolutionary history of strawberries may be useful in other crops where the ancestry is also uncertain. Polyploidy (more than two sets of chromosomes) is very common in wild plants — and occurs in other organisms as well, and I look forward to applying these methods to the study of wild polyploid species for which we know almost nothing about their evolutionary history.'
This article originally appeared on Tallahassee Democrat: Study slices into the complex history of modern strawberry
