The primitive strawberry appeared 7.94 million years ago. At that time the genus Fragaria split into the rose family, The conclusion of Chinese biologists in PNAS Based on genome analysis. Fragaria is now indispensable, with hundreds of cultivated varieties and more than twenty wild species worldwide. In their article, the researchers also described a hitherto unknown species, which occurs in southeastern China.
In recent years, more and more research has been done on the strawberry genome. For example, geneticists published start 2019 Another investigation into natural genetics Which showed that the strawberries we buy in the store contain genes from four wild species.
Chromosomes in eightfold
When these cultivated strawberries have all of their chromosomes in eight, this is not true of most wild strawberries. Fourteen of these species are diploid: each chromosome occurs in two copies, just as in humans. Since diploid species have a relatively small genome (about 300 Mb), they are easy to analyze.
Chinese researchers have also focused on diploid species. They have mapped the genomes of five of those wild species, in order to facilitate future strawberry research. They wrote that strawberries, like cress, could serve as a model plant for genetic research. The diversity of the species, the ease of conducting cultivation experiments, and the relatively small genome make strawberries a suitable candidate.
They immediately set out to work out what such research on strawberries might look like. Not only did they conclude based on genetic information that the genus Fragaria originated nearly 8 million years ago, they also looked at the origins of many specific species. This diversification began about 7.38 million years ago.
Read also: Farm strawberries are descended from four wild species
In the process, the researchers also discovered a new species that was genetically different from the rest. They baptized this species Fragaria emeiensis, named after the Emei Mountains in southern China where it occurs. In any case, the majority of wild diploid strawberries grow only in East Asia. Perhaps this is also the origin of the wild strawberry – and indirectly the origin of the cultivated strawberry. The new species has, among other things, noticeably thickened stems and light green leaves.
Regarding color, biologists made another discovery: they identified several mutations of a particular gene, which cause white instead of red fruits in different varieties of strawberries. These white strawberries are late bloomers: they usually bloom about two weeks slower than their red counterparts.
A version of this article also appeared on NRC on the morning of October 26, 2021
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