Karyotype Analysis And Genome Size Estimation Of Wild Strawberry Species,and Germplasm Innovating Of Fragaria

The strawberry is perennial herb, belonging to the family Rosaceae and the genus Fragaria. The modern, cultivated strawberry(Fragaria×ananassa Duch) originated from the accidental hybridization between the octoploid wild species of F. chiloensis and F. virginiana. The wild strawberry species always show superior characterstics, such as strong aroma and resistances against the diseases and insects. It is desirable to utilize these characters for strawberry breeding. There are decoploid, tetraploid, and pentaploid wild strawberry species found in China, which is one of the countries owning the most numerous wild strawberry species in the word.In order to know the genome size and chromosome characterstics of wild strawberry species better, and to improve the breeding program of wild strawberry by interspecific hybridization and chromosome doubling technique, four aspects were conducted as following:1.The karyotypes of six wild strawberry species were studied by traditional squash technique. The results showed that the karyotype formula of these six wild strawberry species were as follows:F. pentaphylla was2n=2x=14=12m+2sm, F. nilgerrensis was2n=2x=14=8m+6sm, F. viridis was2n=2x=14=10m+2sm+2st, F. mandschurica was2n=2x=14=8m+6sm, F. vesca was2n=2x=14=6m+8sm, F. moupinensis was2n=4x=28=16m+12sm; The karyotypes of all the six species were the type of2A. The evolution order of these six species was probably F. pentaphylla, F. viridis, F. mandschurica, F. nilgerrensis, F. moupinensis and F. vesca.2.The genome size of six wild strawberry species was estimated by flow cytometry, using Arabidopsis thaliana as an internal reference. The results showed that the genome sizes are274±3.80Mb,268±3.73Mb,258±5.40Mb;245±3.28Mb,241±4.28Mb,231±3.19Mb and230±2.83Mb for F. nilgerrensis, F. pentaphylla (red fruit), F. pentaphylla (white fruit), F. moupinensis, F. mandschurica, F. vesca and F. viridis, respectively.3.Interspecific crosses were performed among the cultivated strawberry F. x ananassa ’Fusanoka’,’Benihoppe’ and ’Akihime’(2n=8x=56) as female parents with the wild strawberry species F. viridis (2n=2x=14) and F. mandschurica (2n=2x=14) as male parents. By chromosome number, we identified47pentaploid (2n=5x=35) hybrids in total, which were sterile completely.4. Shoots in vitro from one pentaploid hybrid (designated FxLs-11-37, which was derived from the interspecific hybridization between F.×ananassa ’Fusanoka’ and F. viridis) were treated by different concentrations of colchicines solution. Based on morphological observation and flow cytometry technique,105decaploid (2n=8x=56) plantlets and141mixploid plantlets were identified. The results showed that the treatment with0.1%colchicine for48h induced chromosome doubling at highest rates and the rate of decaploid was42.22%. Compared with the pentaploid plantlets, the decaploid plantlets generally possessed larger, thicker, deeper green leaves and shorter, thicker petiole.