Establishment And Analysis Of Germplasm Characters Of Gynogenetic Topmouth Culter (Culter Alburnus) Population

For purpose of quickly and efficiently improving genetic traits of topmouth culter(Culter alburnus) and setting up new strains which have more economic benefits, firstly,we optimized the methods of topmouth culter gynogenesis to obtain more appropriate induction conditions. Secondly, effective molecular markers AFLP was used for identifying gynogenetic families, which assisted breeding work. Thirdly, observed the embryonic development characteristics and timing differences of gynogenetic diploid and haploid and compared the difference with normal diploid. In order to investigate the influences of cold-shocking of the eggs in C.alburnus and improve management measures of gynogenetic embryo hatching. Fourthly, three kinds of multivariate analysis methods(cluster analysis, principal component analysis and multivariate discrimination analysis) were used to compare morphological differences among normal and gynogenesis C.alburnus groups. Through combining traditional morphological data and truss network data, this work revealed their morphological differences and provided technical parameters and theoretical basis for breeding new C.alburnus strains. The main results were shown as follows:1. Sperms of Cyprinus carpio were inactivated by ultraviolet and the second polar bodies of Culter alburnus were suppressed to promote chromosome diploidization by cold-shocking. The treatment after fertilization(TA) and duration processing time(D)were studied in this study. Results showed that water temperature at 1.5~2.5℃, TA in1~6min were effective time and 4min was optimum, hatching rate and survival rate of gynogenetic diploid were 15.7% and 10.7%. In addition, D in 10~35min were effective and 15 min was optimum, hatching rate and survival rate of gynogenetic diploid larvae were 15.4% and 13.7%. Considering hatching rate, abnormality rate, survival rate and other factors the best parameters for gynogenesis inducing in C.alburnus weredetermined at 4min after cold-shocking insemination and continued for 15 min.2. AFLP could determined the parent-child relationship between 49 gynogenetic offsprings and three candidate mather by 5 sets of primers. Successful induction ratio was 100%, 85% and 100% of family G-1, G-2 and G-3 and average gynogenetic ratio of the three families was 95%. In summary, this method for inducing female nucleus can meet the need of C.alburnus breeding.3. Compared development features and sequence differences of gynogenesis embryos and haploid embryos with normal diploid embryos, it revealed that(1): The fertilization rate of gynogenetic embryos was lower in addition with higher deformity rate. The fertilization rate of haploid embryos and normal diploid had significantly difference and the hatching rate of haploids was extremely low.(2): Gynogenetic embryos appeared anomalous cells, dissolved yolk sacs, eggs membrane ruptureand haploid syndrome after cold-shocking. The death peak appeared in gustrula stage and prehatching stage for each group.(3): Developmental characteristics of gynogenetic diploids were similar with normal embryos, gynogenetic diploid embryos develop slowly especially from the beginning of cleavage to gustrula stage, but after the gustrula stage,development rate was as same as the normal diploids. The incubation time of gynogenetic diploids were 2h 30 min longer than normal diploids group. From the beginning of cleavage to blastula stage, the growth rate of haploid embryos was as much as the normal embryos. But at the time of gastrula stage, it became slower obviously. The same situation were continued in later developmental stages and the haploid syndrome was observed in the haploid larvae.4. Analysis on meristic characters indicated that it could not be accurately determined individuals in any group by this method. Cluster results showed that the first generation artificially induced gynogenetic group(G1)and normal diploid groups cluster together firstly and the second generation artificially induced gynogenetic group(G2)cluster another branch independently. Principal component analysis showed that the most contribution to total variances were head form, tail and body depth among the 27 morphological characteristics. Discriminate formula is established through abstracting eight morphological variables, it found that total discrininat accuracy was 89.2%. In aword, it revealed that morphological variation characteristics of breeding potential in gynogenesis C. alburnus was formed after being bred and selected for several years.