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[摘要]：The strawberry genus, Fragaria (Rosaceae), has a base chromosome number of x = 7. Cultivated strawberries (F. xananassa nothosubsp. ananassa) are octoploid (2n = 8x = 56) and first hybridized from F. chiloensis subsp. chiloensis forma chiloensis x F virginiana subsp. virginiana. Europe has no known native octoploid species, and only one Asian octoploid species has been reported: F. iturupensis, from Iturup Island. Our objective was to examine the chromosomes of F. iturupensis. Ploidy levels of wild strawberry species, include diploid (2n = 2x = 14), tetraploid (2n = 4x = 28), pentaploid (2n = 5x = 35), hexaploid (2n = 6x = 42), octoploid (2n = 8x = 56), and nonaploid (2n = 9x = 63). Artificial triploid (2n = 3x = 21), tetraploid, pentaploid, octoploid, decaploid (2n = 10x = 70), 16-ploid, and 32-ploid plants have been constructed and cultivated. Surprisingly, chromosome counts and flow cytometry revealed that F. iturupensis includes natural decaploid genotypes with 2n = 10x = 70 chromosomes, This report is the first of a naturally occurring decaploid strawberry species. Further research on F iturupensis and exploration on northern Pacific islands is warranted to ascertain the phylogeny and development of American octoploid species. |
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