Analysis Of Genetic Differences In Pengze Crucian Carp Families And Comparison Of The Growth Of Progeny Produced By Heterospermic Gynogenesis

Among the 16 constructed F3 generation families of Pengze crucian carp（family1,family 2,family 4,family 5,family 6,family 9,family 10,family 11,family 12,family 13,family 15,family 20,family 22,family 23,family 24,family 25）,a total of 32 Pengze crucian carp were randomly selected from each family for genetic diversity analysis.In addition,the following four sources of fish sperm were used,including Xingguo Red Carp（divided into inactivated and non inactivated groups）,blunted bream,and Pengze crucian carp,to induce and stimulate the growth and development of the improved female Pengze crucian carp.The growth performance of the offspring produced by the four combinations was compared.The results are as follows:This experiment used 54 pairs of SSR primers and selected 32 Pengze crucian carp as experimental materials to study genetic differences.The results showed that 9 pairs of primers generated 24 alleles between 32 Pengze crucian carp,and each pair of primers amplified 2-3 alleles,with an average of about 2.67 alleles per pair of primers;The effective allele number is 1.4587～2.2530,with an average of 1.8709;The observed heterozygosity ranges from 0 to 0.8438,with an average value of 0.4479;The expected heterozygosity is 0.3194～0.5650,with an average of 0.4668;The variation range of SSR polymorphism information content is 0.3176～0.4806,with an average value of 0.3873.The Shannon’s information index is 0.5671～0.9223,with an average value of 0.7276.The results of SSR markers showed that the genetic diversity level of Pengze crucian carp was moderate.The clustering analysis results showed that the Pengze crucian carp could be divided into two populations by cutting at the genetic similarity coefficient of 0.8900,reflecting a low degree of differentiation among the Pengze crucian carp populations.The association analysis and multiple comparisons of genotypes and growth traits were conducted on the Pengze crucian carp breeding population using the 9 polymorphic microsatellite loci obtained.The results showed that the PZJ-208 locus was significantly correlated with head height,tail stalk height,and body width（P<0.05）,and highly correlated with total length,body length,body height,and body weight（P<0.01）.The average values of the six quantifiable traits in the CCC genotype individuals at the PZJ-208 locus are greater than those in the ABC and AAA genotypes individuals.Four gynogenesis combinations were obtained from Pengze crucian carp induced by four kinds of spermatozoa.Eleven measurable traits such as body weight and body length were measured in the offspring of different month old combinations（40 in each combination）.Using the measured data,the morphological differences of the offspring of the four combinations were compared.The results showed that:（1）The four populations can be divided into three categories,and the population P-P（Pengze crucian carp Pengze crucian carp）and population P-T（Pengze crucian carp blunt bream）were first grouped into one category;And then clustered with the population P-XM（inactivated by Pengze crucian carp Xingguo red carp）into one group;Finally,P-X（Pengze crucian carp Xingguo red carp）gathered into one group.（2）The classification and discrimination results showed that the discrimination accuracy of P-T,P-X,and P-XM was 80%,67.5%,and 77.5%,with a comprehensive discrimination accuracy of 71.9%.（3）In principal component analysis,the cumulative contribution rates of the four components were relatively high,with contribution rates of 21.627%,14.337%,12.972%,and 11.973%,respectively.The cumulative contribution rate was 60.908%.Mapping of principal components 1 and 2revealed that there were many overlaps in measurable traits among the four populations of crucian carp,making it difficult to distinguish them.Using the measured data,the growth performance of four combinations was compared.The results showed that there were differences in the growth speed of each combination throughout the entire growth process.The Pengze crucian carp and Xingguo red carp groups（P-X,P-XM）were significantly higher than the Pengze crucian carp selfing group（P-P）,while the Pengze crucian carp and blunted bream group（P-T）were significantly lower than the Pengze crucian carp selfing group（P-P）.At the same time,fitting the body length and weight data of each month,the growth curve formula of each combination is obtained as follows:P-X:W=0.0208L^3.2112,R²=0.9774;P-XM:W=0.0238L^3.1570,R²=0.9726;P-T:W=0.0177L^3.2689,R²=0.9676;P-P:W=0.0209L^3.1732,R²=0.9721.In this study,microsatellite markers were used to study the genetic diversity of Pengze crucian carp families at the molecular level,and heterosperm gynogenesis was used to obtain high-quality seedlings with potential excellent traits;Provide a theoretical basis for the protection of Pengze crucian carp germplasm resources and the development of new varieties for Pengze crucian carp breeding.