Allotriploid Hybrids Obtained From Interspecific Hybridization Between Chinese Cabbage And Cabbage And The Research On Reproductive Characters

Allotriploid hybrids (2n=3x=29, AAC )were produced by crossing tetraploid Chinese cabbage (Brassica campestris L. ssp. pekimnsis AAAA, 2n=4x=40) and diploid cabbage (B. oleracea var. capitata L. CC, 2n=2x=18) using overy and ovule culture method, which will be used for constructing Chinese cabbage-cabbage addition lines, substitution lines and translocation lines. The morphology, cytology, and pollen characters of the allotriploid hybrids were studied, which provided theoretic basis for obtained alien addition lines, alien substitutioin lines and translocation lines. The homologization between genome A and genome C in Brassica was assessed preliminarily, and genome in situ hybridization between genome A and genome C was also explored, which will be used for studying on composition, originate and evolution of genomes A and C. Conclutions were followed:1 When tetraploid Chinese cabbage was selected as female parent, the pollination and fertilizatin of hybridization between tetraploid Chinese cabbage and diploid cabbage were easier than diploid cabbage as female parent. The obstacle in the interspecific cross resulted from the incompatibility before fertilization and the difficulty of embryos development after fertilization, but the latter was the main reason. The death of young embryo was overcomed and allotriploid hybrids were obtained using overy and ovule culture method.The pistils of 5-7 days after pollination were suitable for overy culture, the rate of survival ovule in one pod was 28% on the improved White medium; Based on the different mediums selection, the improved White mediums was optional for the development of the overy culture. And high prequency of survival ovule was observed, which was up to 14.1%; 28 days after ovary culture, the survival ovules were taken out and cultured on the improved Hiidebrandt medium, which was suitable for ovule culture, and the survival rate was up to 80%.2 The allotriploid hybrids were similiar in morphological characters to Chinese cabbage, however 4-6 pairs small leaves were lined at the petiole of basilar leaves, the growth vigor was strong and the stem elongated quickly up to a height of about 2m at flowering stage. The number of root tip chromosomes was 29.3 The results of reproductive characters research indicated: (1)Chromosomes from Chinese cabbage and cabbage couldn't be obviously divided into two parts at prophase I during meosis; There were high frequently trivalent even quadrivalent, which indicated that high homologization between Chinese cabbage and cabbage was involved; Serveral dissociative chromosomes were observed at methaphase I ; There were distributions of 13-16, 14-15,...