Researchers say new information about the strawberry genome will boost breeding efforts, and could lead to a better tasting berry.
A near-complete reference genome of the strawberry was reported in a paper published online this week in Nature Genetics.
The genome of the commonly cultivated strawberry has revealed it is related to four different types of wild strawberry and that it likely had its origins in North America more than 1 million years ago.
Researchers said the commonly farmed strawberry has eight sets of chromosomes (unlike our two) making it very complicated at a DNA level.
They found the eight sets of chromosomes could be traced back to four wild strawberry ancestors.
The complicated DNA combinations that could arise from having eight sets of chromosomes were also found to be dominated by just one of these ancestors, whose genes largely controlled disease-resistance and the pathways that give rise to strawberry flavour, colour, and aroma.
Researchers said the genome provided new insights into the origin and evolutionary history of the popular fruit.
The cultivated octoploid strawberry (Fragaria × ananassa cultivar 'Camarosa') has eight sets of chromosomes.
Also known as the garden strawberry, it is popular for its flavours and aromas.
Patrick Edger and colleagues report a high-quality assembly and annotation of the octoploid strawberry genome, identifying more than 100,000 strawberry genes.
The authors sequenced 31 sets of RNA molecules from diploid Fragaria species (strawberry species with two sets of chromosomes) and compared the sequences of expressed genes of diploid species with those of F. × ananassa.
The authors were then able to identify Fragaria vesca, Fragaria iinumae, and previously unknown Fragaria viridis and Fragaria nipponica as four diploid ancestral species of F. × ananassa, according to evolutionary analysis.
These analyses, combined with the geographic distributions of extant species, suggest that the octoploid strawberry originated in North America.
In addition, the authors analysed the evolutionary dynamics among the four subgenomes of the octoploid strawberry.
This analysis revealed the presence of a single dominant subgenome, which largely controls metabolomic and disease-resistance traits in strawberry.
The authors conclude that the evolution and origin of the strawberry and the discovery of a dominant subgenome, along with the first high-quality genome for an octoploid strawberry, may provide a powerful resource for researchers and breeders to improve the flavours, aromas and disease resistance of the cultivated garden strawberry.