Production And Molecular Cytogenetics Of Interspecific Hybrids From The Crosses Of Fragaria Nilgerrensis ×F.ananassa And F.mandschurica ×F.ananassa

With the market rapid enlargement around the domestic and oversea, there has been seen a quickly developing of strawberry industry in the latest years. Currently, all of the cultivars of strawberry in our country were introduced from aboard or breed from the crosses between the foreign cultivars, therefore, narrow original genetic background of cultivar's parents will inevitably cause it more difficult to make a great breakthrough in genetic improvement of strawberry cultivars. There are about 50 species in Fragaria, at least 10 species of them can be found in our country. Among the abundant wild resources, many of them possess with characteristic such as the resistance to diseases, particular fragrance and so on. Corporation such excellent genes from wild species into cultivars will be significant for improve their characteristic. Besides, there still have never been reported about the situation of wild species originated from China in evolution of strawberry, research on cytogenetics of hybrids from the cross of wild species originated from China with cultivars of Fragaria will also be helpful for understand the relationship between wild species and cultivars and strawberry origin and evolution.Two wild species including Fragaria nilgerrensis and F. mandschurica which originated from China were crossed with cultivars F. ananassa. Embryo rescue was studied for interspecific hybridization, and high frequency of hybrids was obtained. Rate of plantlet was effected by culture medium, period of embryo development and different parental combination. The frequency of plantlet was highest on MS medium with addition of 1mg/L BA, 5mg/L 2,4-D and 0.5g/L casein hydrolysate. Optimum time was from 21 days to 25days after pollination. Eymbryo rescue technique system of the crosses between diploid and octoploid of Fragaria was established, the highest ratio of plantlet among all crosses was 43.2% in cross of F. mandschurica X F. ananassa cv. 'Chunxiao'.The interspecific hybrids from the crosses between Fragaria nilgerrensis, F. mandschurica, two diploid species derived from China, and cultivars of F ananassa (2n=8x=56) were obtained, and the number of chromosome, plant morphology, laef spot and anthracine deseases resistance were studied. The hybrids F1 of cross F nilgerrensis X F. ananassa were pentaploids and self sterile. The surveyed hybrids morphologically intermediate between their parents in plant height, plant form, leaf shape, leaflet form and hair of ptiole;Other morphology traits including runner and leaf color, peduncle height, hair of peduncle of hybrids inclined predominantly to female parent F nilgerrensis. The hybrids Fl of cross F. mandschurica X F. ananassa were also pentaploids and self sterile. Hair of petiole and peduncle of hybrids inclined predominantly to female parent F. mandschurica. Plant height of hybrids Fl was intermediate between their parents but most of them were inclined to F ananassa. The evaluation of hybrids to strawberry leaf spot and anthracnose in field showed hybrids with better resistance to the diseases than cultivatedvariety parents were obtained by interspecific hybridization.The hybrids of F. nilgerrensis X F. ananassa had a meiotic chromosome association of 7.55 I +12.97 II+0.29III+0.16IV, tetrad phase of hybrids also showed about 26% different microspores occurred. Possible no homology between F. nilgerrensis and F. ananassa is to be thought due to the cytogenetic analysis. Compering with the hybrids of F. nilgerrensis X F ananassa in cytogenetics, there are more multivalents in meiotic chromosome of hybrids Fl from F. mandschurica X F. ananassa. Its configuration of meiotic chromosome in PMC was 6.1 I +10.6II+2.1III+0.35IV. There is thus an indication of homology to some extent between F. mandschurica and F. ananassa. It is presumed that F. mandschurica is a mutant of F. vesca in some possibility according to other reports and comparatively of morphology between F. mandschurica and F. vesca.To study the effect of Fragaria interspecific hybrid breeding on molecular level, the 14 accessions from interspecific hybrids of 2 crosses combinations between F. nilgerrensis and F. ananassa and 10 accessions from interspecific hybrids between F. mandschurica and F. ananassa were analysis by the techniques of RAPD-PCR. The main results showed specific DNA fragments of parents including F. nilgerrensis, F. mandschurica and cultivars of F. ananassa were observed in RAPD pattens of 24 accessions. It proved the effect of Fragaria interspecific hybrid breeding on molecular level.There were distinct differences of genome DNA among the interspecific hybrid accessions, we could distinguish among 10 accessions from the cross of F. nilgerrensis and F. ananassa cv. Chunxiao by using 2 primers SI371 ^0 SI405, 4 accessions from the cross of F. nilgerrensis and F. ananassa cv. Shuoxiang by using each of 5 primers S137K S1380^ S1397> S1404> S1405, and 10 accessions from the cross of F. mandschurica and F. ananassa cv. Shenxing by using primers S1402.GISH with DIG labeled genomic DNA of F. nilgerrensis as a probe and genomic DNA of F. ananassa as a blocker was used to identify alien chromosome in F. ananassa background. The result showed the chromosome of nilgerrensis could be examed in RTC of hybrid of F. nilgerrensis X F. ananassa by GISH, it alsos proved the effect of interspecific hybridization.Chromosome doubling in F. nilgerrensis X F. ananassa was induced with colchicines through meristem culture in medium, and decaploid of F. nilgerrensis X F ananassa was obtained. The doubled plant was characterized with lower height, more stocky than its parents, the berry of decapoid was well developed and had particular fragrance of F. nilgerrensis.