| Haliotis discus hannai, which belongs to Gastropoda, is one of the important economic species, and is widely distributed around the coast in the north of China. Because of its delicious meat and high nutritional value, it is known as "seafood treasures." However, with the rapid development of industrialized and intensive farming, as well as frequent hybridization and inbred, that resulting in a gradual reduction of the effective parent population of hybrid abalone and the decline of genetic diversity. Furthermore, the advantage of growth and quality in hybrid abalone has been decreased gradually. Therefore, only one effective way for us to improve the quality of the abalone in our country was to breeding new varieties with a higher quality, fast-growing and disease-resistant ability. The study included three parts which were all based on the employing of a full-factorial mating design(F1) consisting of 3 dams and 10 sires in 2013. Firstly, analyzing the differences in the growth and immunity between different color eggs of juvenile abalone that from 16 months. Secondly, carrying out a paternity test about 608 individuals that from 30 full-sib families of second age of F1 generation. Thirdly, conducting the genetic analysis combined with growth traits(shell length, shell width, and the total weight) on the base of SSR.The major results and conclusions are as follows:1. Growth and immune diversity of H.discus hannai juvenile abalone with different egg color100 samples from 3♀×10♂ full-sib families family of H.discus hannai were selected randomly as experimental materials in this study. After classifying the samples according to the sexuality and egg color, we measured the growth traits(the total weight, shell length and shell width) and activity of five enzymes which including superoxide dismutase(SOD),alkaline phosphatase(AKP),acid phosphatase(ACP),catalase(CAT) and lysozyme(LZM), and the single factor variance analysis was conducted. The results showed that: for growth traits, there was no significantly difference between different egg color(P>0.05), but the data(x±SD) of green egg were higher than the other three egg color samples; for immunity, there was no significantly difference in the activity of SOD and CAT among four kinds of egg color(P>0.05), but the activity of AKP, ACP, LZM showed significantly difference between green eggs and brown, and brown red eggs, the immune enzyme activity order to juvenile H.discus hannai was descendantly ranged as green > brown-green > brown > brown-red. These results provided a theoretical basis for breeding new varieties with a higher quality, fast-growing and disease-resistant ability through egg color.2. Parentage and microsatellite loci information assignmentA total of 608 individuals from F1 were genotyped using eight microsatellite markers(CHd092, CHh103, CHh126, CHd205, CHd667, CHd818, CH1820 and ddh41): 521 individuals were successfully assigned to a single parent, except 87 were identified as contaminants. The results showed that: the number of alleles was 147, the average number of alleles was 18.4; the observed heterozygosity(Ho) and expected heterozygosity(He) was 0.527 and 0.806, respectively; the polymorphic information content(PIC) ranged from 0.609 to 0.908, and the average was 0.785. The exclude cumulative rates were respectively 0.9974, 0.9999, 1.0000 analyzed by CERVUS 3.0.3. Genetic parameters and correlation analysis for target traits of the H.discus hannaiThe three growth traits heritability and correlation analysis which included total weight, shell length and shell width were estimated by using three kinds of heritability estimation model in H.discus hannai. In the aspect of growth traits, three families which include Sire3-Dam1, Sire7-Dam1, and Sire10-Dam3 were all better than others in three growth traits according to the analysis datas. And the survival rate of these three families was higher for the dominant of family counts. So we can choose these growth traits in the next breeding work. The growth index of three families(S3D1, S7D1, S10D3) were better than other families, and the individual numbers were dominant, while n >20(individuals per families). This results of growth traits reflected the survival rate of these three families were higher than other families, that provided a reference for the future breeding programs. The heritability of shell width, Shell length the total weight of growth traits were 0.391±0.176, 0.385±0.164, 0.350±0.158, respectively. Phenotypic and genetic correlations between traits were positively correlated(genetic correlation value >0.9, phenotype correlation value > 0.8), and the two related values are high correlation. It suggested that these three traits would get a larger genetic improvement after artificial breeding. These estimates falling in the 0.3-0.5 range belonged to medium-high heritability. Gentic correlation and phenotypic correlation between the various growth traits was positive, the value of genetic correlation was above 0.9 and the value of phenotypic correlation was above 0.8, both values were the medium-high correlation, It suggested that these three traits would get larger genetic improvement after breeding. |
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