| Hyriopsis cumingii is China's most important freshwater mussel for pearl production.The pearls produced are mainly white,and rare precious pearls such as purple and gold are produced occasionally.In recent years,the work aiming at improving germplasm resources of Hyriopsis cumingii has been carried out,and the selection of an excellent strain Hyriopsis cumingii is one of the effective ways to improve pearl quality.In the process of breeding,it is necessary to analyze the genetic parameters of target traits and the interaction between genotype and environment.The research on purple and white pearls has been carried out for a long time in our laboratory,and golden pearls are also a kind of favorite category of consumers.Therefore,in this study,the breeding effect was evaluated with the golden strain Hyriopsis cumingii as the material and the growth character and shell color as the objective;The genealogy identification was carried out using the paternity testing technique,and the genetic traits and interaction effects of genotype and environment were analyzed for the growth traits,inner shell color parameters a,b,L and d E of all the families;For the first time,the glossiness of the inner shell in the first generation were analyzed by the glossiness measuring instrument.It mainly includes the following contents:1.Evaluation on the breeding effect in the first generation of golden strain Hyriopsis cumingiiThe golden Hyriopsis cumingii with good growth and gonad development was selected as parents,and 19 half sib mother strains Hyriopsis cumingii were bred in Wuyi,Zhejiang and Chongming,Shanghai.41 whole sib families were obtained after parent-child identification.The growth characters and inner shell color parameters a,b,L and d E of these 41 families were selected and evaluated.The results showed that thegrowth traits of F12,F24,F25,f29 and F30 families in Chongming,Shanghai were the best,and F18,F19,F21,F24 and F25 were the best families in Wuyi,Zhejiang,which indicated that the culture environment had a greater impact on the growth of Hyriopsis cumingii,among which F24 and F25 were excellent in both places,and had a wider adaptability to the environment.The average values of a and b are greater than 0,and the range of b value greater than 0 is greater than a value,indicating that the inner shell color of golden breeding strain of Hyriopsis cumingii is more yellow,which can be used as the breeding target.Compr ehensive evaluation of growth traits and inner shell color,breeding families with good growth traits can promote families F24 and F25 in the Wuyi environment,while breeding families with deep inner shell colors can promote Shanghai Chongming F15,F24,F25 and F34 The pedigrees,the F24 and F25 pedigrees,can be focused on in the next selection process,in order to make them have excellent growth traits and dark inner shell color in the same environment.2.Estimation of genetic parameters of growth traits and environmental interaction in the first generation of Hyriopsis cumingiiUsing 6 pairs of microsatellite markers,19 matrilineal and half sib families in two breeding sites were identified and analyzed.A total of 9 paternal and half sib families and 41 full sib families were obtained.The genetic parameters of growth traits were evaluated by pedigree information.The results showed that the golden strain of Hyriopsis cumingii had high genetic polymorphisms at six loci,the average expected heterozygosity He was 0.842,and the average polymorphic information content PIC was 0.819.The heritability of shell length,height,width,and body weight of the golden strain Hyriopsis cumingii were 0.18 ± 0.07,0.19 ± 0.03,0.22 ± 0.09,and 0.18 ± 0.09 at the age of 5 months,at the age of 17 months,they were 0.26 ± 0.22,0.30 ± 0.16,0.30 ±0.09,0.23 ± 0.25,all belonged to middle heritability.At the age of 5 months,the genetic correlation ranged from 0.84 ± 0.02 to 0.96 ± 0.07,and the phenotypic correlation ranged from 0.56 ± 0.02 to 0.92 ± 0.04;At the age of 17 months,the genetic correlation ranged from 0.52 ± 0.03 to 0.97 ± 0.06,and the phenotypic correlation ranged from 0.45± 0.02 to 0.91 ± 0.01,indicating that each growth trait can be selected indirectly.The genetic correlation coefficient of every character of Hyriopsis cumingii was 0.53 ± 0.14? 0.57 ± 0.12 at 5 months old and 0.27 ± 0.08 ? 0.31 ± 0.09 at 17 months old,which indicated that there was significant interaction between genotype and environment.In this study,it was clarified that both 5-month-old and 17-month-old could obtain betterimprovement effect in the breeding of golden strain of Hyriopsis cumingii,which provide theoretical basis for genetic improvement of golden strain Hyriopsis cumingii.3.Genetic parameter estimation and environmental interaction effect of inner shell color in the first generation of golden strain Hyriopsis cumingiiThe results showed that the heritability ranged from 0.12 ± 0.03 to 0.14 ± 0.05,the genetic correlation ranged from-0.75 ± 0.11 to 0.74 ± 0.12,and the phenotypic correlation ranged from-0.82 ± 0.01 to 0.54 ± 0.03.The color parameters a,b,L,and d E values all belong to the middle and low heritability.In the genetic correlation,a value and b value,d E value,b value and L value,L value and d E value were all negative correlation,and L value and d E value had the strongest negative correlation of-0.75 ± 0.11;In phenotypic correlation,L value was negatively correlated with a value,b value and d E value,and the strongest negative correlation between L value and d E value was-0.82 ± 0.01.The genetic correlation of shell color parameters in Wuyi and Chongming ranges from 0.05 ± 0.25 to 0.44 ± 0.21,both of which are less than 0.8,with obvious genetic environment interaction effects.Therefore,the interaction between genotype and environment should be fully considered in the next step of shell color breeding.Continuous breeding can further improve the inner shell color of golden strain Hyriopsis cumingii.4.Estimation of genetic parameters and environmental interaction effect of inner shell glossiness in the first generation of golden strain Hyriopsis cumingiiIn this experiment,the glossiness of inner shell of 2-year-old golden strain Hyriopsis cumingii was evaluated by using the glossiness of small hole surface.The results showed that the heritability of inner shell glossiness was 0.28 ± 0.07,which belonged to medium heritability.The genetic correlation of glossiness in Wuyi and Chongming was 0.55 ± 0.19,which had a certain genetic environment interaction effect.The genetic correlation and phenotypic correlation between inner shell glossiness and growth traits and color are all weak negative correlation,but the correlation is not significant,which indicates that it is impossible to indirectly select inner shell glossiness by breeding growth traits.Since the d E value has the greatest negative correlation with glossiness,the glossiness will decrease as the color becomes darker,probably because the pigment accumulates in the clam shell,which causes the light refraction to change accordingly.Therefore,the interaction between color and luster should be fully considered in the next selection process,and the correlation between color and lustershould be further explored through multi generation selection. |
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