Morphological and polyploidy variation of strawberry plants obtained by cross pollination of Fragaria vesca and F. × ananassa.

For future production in Japan using genetically modified (GM) octoploid strawberry plants, the possibility exists of genetic pollution of wild diploid strawberry plants through spontaneous hybridization with GM plants. The objective of this study was to clarify the possibility of hybridization between an octoploid cultivar and F. vesca, which is the most closely related species to octoploid species. As male and female parents, F. × ananassa cv. 'Sachinoka' (2n=56) and F. vesca cv. 'Baron Solemacher' (2n=14) were used, respectively. In all, 66 seedlings were obtained from 100 seeds. The petiole length, the leaf blade length and width, and the numbers of runners, vegetative buds and inflorescences were recorded. In addition, polyploidy levels of the hybrid plants were analyzed using flow cytometry and chromosome counting. The hybrids were divided into A type (23 plants) and B type (43 plants) according to their morphological characteristics. Results of flow-cytometry analysis and chromosome counting showed that A type was a diploid of F. vesca and that B type was a hybrid of pentaploid. Consequently, we inferred that hybrids that had the genes of octoploid strawberry cultivars appeared at high frequency.