Whereas most species are diploid, strawberry is an octoploid, with eight copies of the genome from multiple, distinct parental species. The research, published in Nature Genetics, unveils how strawberry became an octoploid. Patrick Edger, MSU assistant professor of horticulture and co-author on the paper said that they identified all four extant relatives of the diploid species that sequentially hybridized to create the octoploid strawberry.
The four diploid species are native to Europe, Asia, and North America, but wild octoploids are almost exclusively distributed across the Americas. The results also suggest a series of intermediate polyploids, tetraploid, and hexaploid that formed in Asia, before the octoploid event that occurred in North America, involving the hexaploid and a diploid species endemic to Canada and the United States. According to Edger, they found that one of the parental species in the octoploid controls fruit quality and disease resistance traits, and they have identified genes controlling various target traits.