| Grass carp(Ctenopharyngodon idella)is the highest yield of fish in the world.In recent years,due to the decline of genetic resources,the main economic traits have been degraded at parents and offspring.Conservation and development need to be urgently carried out about the genetic resources of grass carp.In this study,the complete diallel hybridization was carried out in the grass carp of Yangtze River,Pearl River and Heilongjiang River,and the growth performance was compared from nine groups of grass carp.The genetic variation parameters were analyzed from nine groups of grass carp by microsatellite multiplex PCR?Nine groups of grass carp were used to develop SNP loci related to growth traits in IGF-2a gene,which provided theoretical basis for genetic evaluation and utilization of grass carp,and laid a foundation for further stock renewal and genetic improvement of grass carp.This experiment included the following three aspects:1.The body weight and body length were compared from grass carp of nine groups at 80 and 170 days of age.It could be seen that at 80-day-old stage,hybrid groups generally showed growth advantages over self-propagation groups,and at 170-day-old stage,the growth differences among the groups were gradually significant.Among the growth intervals from 80 to 170 days,the group of Yangtze River x Pearl River(CZ)grew fastest(AGR=0.166),and the group of Heilongjiang x Heilongjiang(HH)grew slowest among the nine groups(AGR=0.079).6 hybrid groups generally had higher weight gain rate than self-propagating groups,and the hybrid groups showed greater advantages.The relative weight gain rate of the Yangtze River x Zhujiang(CZ)was the highest among the nine groups(RGR=0.035).The relative weight gain rate of Heilongjiang x Heilongjiang(HH)and Heilongjiang x Yangtze River(HC)were all 0.025.The above data showed that the hybrid groups represented by the Yangtze River x Zhujiang(CZ)had obvious advantages over the self-breeding groups.2.The genetic variation of microsatellite sequences was analyzed in 9 groups of grass carp by multiplex PCR.The results showed that the average number of alleles(Na)was 5.75-12.33,the average number of effective alleles(Ne)was 3.8077-6.3065,the average observed heterozygosity(Ho)was 0.7682-0.9036.The average expected heterozygosity(He)was 0.8385-0.6210 and the polymorphism information content(PIC)of 12 microsatellite loci in 9 groups of grass carp showed a high level of genetic diversity.They were 0.892,0.823,0.857,0.894,0.927,0.859,0.850,0.859,0.859,0.907,0.929,0.879 and 0.749.UPGMA phylogenetic tree construct based on genetic similarity and genetic distance of different groups of Nei's showed that the information of genetic diversity and genetic differentiation of hybrid groups was generally higher than that of self-breeding groups.The results showed that the overall hybridization effect was obvious,and the distant hybridization superiority could be better reflected by the stock hybridization breeding of grass carp from different geographical sources,which provided theoretical basis for the improved strains of grass carp.3.In this study,10 SNP loci were detected by splicing the IGF2-a gene sequence of grass carp and correlated with the body length,body weight and fatness of important economic traits of grass carp.The results showed that 8 of the 10 loci detected were significantly correlated with growth traits.The results showed that the genetic diversity of the groups of grass carp obtained by complete diallel crossing was high.If these mutation loci could be well correlated with growth economic traits,it would be helpful for marker-assisted breeding.It was found that the mutant genotypes of SNP1,SNP2,SNP3,SNP4,SNP5,SNP6,SNP7 and SNP10 had significant differences in body length and body weight during the initial growth and development of grass carp,while SNP11 and SNP12 had no significant relationship in body length and body weight.It was speculated that the above loci had a good mutation advantage for the early growth and development of grass carp. |
PDF Full Text Request