| Distant hybridization happens between different genera or even more distantly related species. Through hybridization, different generas characters can be combined, so that new species which the people wanted by breaking species bonndaries could be achieved. Distant hybridization is the important method for fish breeding.In the present study, two groups with different genetic background were obtained by intergeneric crossing Megalobrama amblycephala(♀) with Erythroculter ilishaeformis(♂). Our results showed that the fertilizing rates(90.0%) and hatching rates(80.6%) in intergeneric cross group were high. Both hybrids A(96.2%)and hybrids B(3.8%) were obtained, the Morphological characters of hybrids A were between its parents, the hybrids B had the same morphological characters to the female parent of Megalobrama amblycephala. The relative DNA content of hybrids was examined by means of Flow Cytometery. The results showed that the hybrids A and B were diploid with the same DNA contents as their parents. The chromosome analysis showed that hybrids A and B individuals had the same chromosome number as their parents’(2n=48). Two pairs of specific loci(TTF6 and TTF10) were screened by SSR analysis. The results indicated that hybrids A inhertited the genetic materials from both female and male parents respectively. The hybrids B inherited only the maternal genetic materials which show it is gynogenetic progenies. The hybrids A grew faster than both M. amblycephala and E. ilishaeformis, which suggest an obvious growth advantage in the earth pond. Our studies shine a light on constrution a novel hybrid strain by intergeneric cross between Parabramis and Culter. In addition, the production of gynogenetic progenies can be applied to establish the pure line of M. amblycephala.For the purpose of germplasm identification and genetic diversity analysis of Ctenopharyngodon idella in different regions, we find 181 microsatellite loci from 2400 EST sequences. 9 pairs of primers which could give stable and polymorphic amplification profiles were screened out from 46 microsatellite loci and used to analyze the genetic structure of Ctenopharyngodon idella. The 9 pairs of primers were used to analyze the genetic structure of 8 populations of the Yangtze River(CSC, AQC, JXC, JJC, SSC, SJC, RCC and HJC) and 1 red population(HC). The mean value of number on alleles(Na) of CSC, AQC, JXC, JJC, SSC, SJC, RCC, HJC and HC was 4.67, 5.22, 5.33, 5.00, 4.89, 4.78, 4.89, 4.67 and 2.56, the mean value of expected heterozygosity(He) was 0.6397, 0.6543, 0.6831, 0.6356, 0.6737, 0.6483, 0.6664, 0.7129 and 0.4696, and the average value of polymorphism information content(PIC) was 0.5787, 0.6126, 0.6283, 0.5894, 0.6217, 0.5956, 0.6136, 0.6582 and 0.3949, respectively. It demonstrated that the genetic diversity of HJC was the highest and HC was the lowest among the nine populations. Using Unweighted pair-group method with arithmetic means method(UPGMA) based on their genetic distances, the cluster analysis in nine populations showed that 8 populations of the Yangtze River first grouped together, then they clustered with the red population. In addition, the genetic distance between AQC and SJC was 0.0725, which was the nearest, the genetic distance between HC and CSC was 0.5217, which was the farthest. It is significant in germplasm resources preservation, germplasm identification and breeding of Ctenopharyngodon idella.In this study, to obtain gynogenetic grass carp,we induced grass carp eggs using UV-irradiated M. amblycephala sperm, then cold shock started 3 min after fertilizaation and continued for 12 min in 4-6℃ cold water to retain the second polar body. The experiment could obtain survivable individuals, and the fertilization rate, hatching rate and survival rate at the first feeding were 70.78%、21.51%、4.58%, respectively. we checked the individuals by morphological characteristics, the gynogenesis grass carp were similar to common grass carp. Because M. amblycephala and grass carp belong to different subfamilies in zootaxy, so using UV-irradiated sperm of M. amblycephala make it more easily to distinguish gynogenetic grass carp from the control hybrids just according to the morphological characteristics. Microsatellite analysis indicated that the alleles number the of the gynogenesis grass carp was less and it’s purity was higher than the common grass carp. |
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