Cultivation method of fast-growing high-survival-rate triploid Fujian oyster improved strain

Abstract

According to the method, firstly, the Fujian oyster black shell diploid strain and the Fujian oyster gold shell diploid strain which are pure in shell color and fast in growth are obtained through population breeding, and then the new diploid Fujian oyster strain which is fast in growth speed and high in survival rate is obtained through cross breeding. Secondly, the improved tetraploid Fujian oyster shell black strain which is fast in growth, high in genetic diversity and high and stable in tetraploid multiplying power is obtained in a group breeding and family breeding mode. And finally, hybridizing the obtained diploid Fujian oyster new strain as a female parent and the tetraploid Fujian oyster shell black improved strain as a male parent to breed a fast-growing high-survival-rate triploid Fujian oyster improved strain. The method has the excellent characteristics of high survival rate, high growth speed, high yield and the like, is suitable for being popularized and cultured in southern coastal areas such as Fujian and Guangdong in China, and has a wide industrial application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of shellfish breeding, and in particular relates to a method for cultivating a fast-growing and high-survival rate triploid Fujian oyster improved strain. Background Art

[0002] Oyster farming plays an important role in my country's marine aquaculture industry. In 2023, the total output of oyster farming was 6.6712 million tons, accounting for 40.53% of the total output of marine aquaculture shellfish in China (China Fisheries Statistical Yearbook, 2024). In recent years, polyploid breeding technology has attracted much attention. Compared with diploid oysters, triploid oysters have the advantages of fast growth, low fecundity, and large size. In addition, triploid oysters can still be supplied to the market normally in summer due to their sterility to meet consumer demand.

[0003] Since triploids cannot produce viable offspring, when genetically improving triploids, the diploid or tetraploid parents are often improved, and then the excellent traits of the parents are combined through ploidy breeding and hybrid breeding to achieve the purpose of genetic improvement of triploids. This has been widely used in triploid long oysters and triploid American oysters.

[0004] As a shellfish with the highest aquaculture output, Fujian oysters are widely cultivated in southern coastal areas such as Fujian and Guangdong in my country. The annual output in 2022 is about 2.415 million tons, accounting for 38% of the total production of aquaculture oysters in the country (China Fisheries Statistical Yearbook, 2023). However, diploid Fujian oysters have defects such as small individuals and long breeding cycles. In recent years, although triploid Fujian oysters have been widely used in the industry. However, it was found during the breeding process that triploid Fujian oysters cultivated by traditional methods grew slowly and had a high mortality rate. Therefore, there is an urgent need to genetically improve traditional triploid Fujian oysters to meet industry needs. Summary of the invention

[0005] In order to overcome the problems of slow growth and high mortality of traditional triploid Fujian oysters in my country, the present invention develops a breeding method for a fast-growing and high-survival rate improved strain of triploid Fujian oysters, which can provide a theoretical and practical basis for the breeding and industrialization of excellent varieties of Fujian oysters.

[0006] A method for cultivating a fast-growing, high-survival rate triploid Fujian oyster improved strain, characterized by comprising the following steps:

[0007] a. Selecting diploid Fujian oysters with golden and black shell colors as broodstock, improving the shell color and growth traits through group breeding, and obtaining diploid Fujian oysters with golden and black shells;

[0008] b. By hybridizing between selected strains, the additive genetic variance accumulated in the two strains of Shell Gold and Shell Black during the breeding process and the non-additive genetic variance between strains were combined to obtain a new hybrid strain of diploid Fujian oysters with fast growth rate and high survival rate;

[0009] c. Using the diploid Fujian oyster shell black strain as the male and female parent, the triploid Fujian oyster shell black strain was induced to obtain the triploid Fujian oyster shell black strain; using the triploid Fujian oyster shell black strain as the female parent and the diploid Fujian oyster shell black strain as the male parent, the tetraploid Fujian oyster shell black strain was induced to obtain the tetraploid Fujian oyster shell black strain;

[0010] d. Directed selection of the shell color, growth and fecundity of the tetraploid Fujian oyster black shell strain was carried out through group selection and family selection, so as to obtain an improved tetraploid Fujian oyster black shell strain with pure shell color, fast growth rate and high fecundity;

[0011] e. Using the diploid Fujian oyster hybrid new strain described in step (b) as the female parent and the tetraploid Fujian oyster black shell improved strain described in step (d) as the male parent, hybridization can obtain a fast-growing and high-survival rate triploid Fujian oyster improved strain.

[0012] Furthermore, in step (a), oysters with good vitality, beautiful and undamaged shells, and pure gold or pure black shells on both sides are selected as broodstock for the two basic groups. When performing group breeding, the top 10% of individuals in terms of shell height and wet weight are selected, and high-intensity breeding is continued for 3 to 4 generations.

[0013] Furthermore, in the step (b), when hybridization is performed, individuals with high shell height and large total weight are preferred, and at least 50 male and female parents are selected from the black shell and gold shell strains, respectively, and fertilized at a ratio of sperm:egg=50:1.

[0014] Furthermore, in the step (c), the triploid Fujian oyster black shell strain is induced, and individuals with pure black color, high shell height and total weight are selected from the diploid Fujian oyster black shell strain as parents, among which, individuals with neat development, ≥15 million eggs and dark yolk color are preferred as female parents, and individuals with full gonads and vigorous sperm are preferred as male parents, and sperm and eggs are obtained by the "dry stripping method".

[0015] Furthermore, in the step (c), the triploid Fujian oyster black shell strain is induced by fertilization at a ratio of sperm:egg = 50:1, and 0.75 mg / L of cytochalasin B is added 15 minutes after fertilization to inhibit the release of the second polar body of the fertilized egg. After continuous treatment for 15 minutes, the fertilized eggs are soaked in 2 mg / L dimethyl sulfoxide solution and seawater, and the ploidy of the larvae is determined after hatching and selection. The group with a triploid rate of more than 95% is retained, and the larvae are cultured and grown into adult shells using conventional methods to obtain the triploid Fujian oyster black shell induced strain.

[0016] Furthermore, in the step (c), the tetraploid Fujian oyster shell black strain is induced, and individuals with neat development, ≥15 million eggs, and dark yolk color are selected from the triploid Fujian oyster shell black strain as the female parent, and individuals with vigorous sperm motility are selected from the diploid Fujian oyster shell black strain as the male parent, and fertilization is carried out at a ratio of sperm:egg = 50:1. 1 mg / L of cytochalasin B is added 8 to 10 minutes after fertilization to inhibit the release of the first polar body of the fertilized egg. The group without reagent is used as the control group. When the first polar body appears in 50% of the fertilized eggs in the control group, the eggs are washed, and the ploidy of the larvae is determined after hatching and selection. The group with a tetraploid rate of more than 80% is retained, and the larvae are cultured and grown into adult shells using conventional methods to obtain the tetraploid Fujian oyster shell black induced strain.

[0017] Furthermore, in the step (d), when performing population breeding, the black-shell tetraploid Fujian oyster with pure black shell color, large shell height and total weight, and high fertility is preferably used as the parent, and the top 10% of individuals in shell height and total weight are cut, and more than 50 males and females are selected in each generation, and fertilization is carried out at a ratio of sperm:egg=50:1, and high-intensity breeding is continued for 2 to 3 generations.

[0018] Furthermore, in step (d), when population selection is performed, step (c) is repeated to obtain black-shelled tetraploid Fujian oysters with different genetic backgrounds, and these are continuously added to the original tetraploid population to ensure high genetic diversity of the black-shelled tetraploid Fujian oyster population.

[0019] Furthermore, in the step (d), when family selection is performed, tetraploid Fujian oysters with pure black shell color, high shell height and total weight, and high fertility are preferably used as parents, and 40-50 full-sib families are established by one-to-one fertilization. After the gonads of the previous generation family mature, families with pure black shell color and a tetraploid rate greater than 95% are preferably used as parents of the next generation family. Tetraploid individuals from different families are fertilized one-to-one to obtain the next generation family. After 2 to 3 consecutive generations of family selection, a tetraploid Fujian oyster black shell improved strain with a high tetraploid rate, pure shell color, and high fertility can be obtained.

[0020] Furthermore, in the step (e), individuals with neat development, 15 million or more eggs and dark yolk color are selected from the diploid Fujian oyster hybrid new strain as the female parent, and individuals with pure black shell color and vigorous sperm are selected from the tetraploid Fujian oyster black shell improved strain as the male parent. Fertilization is carried out at a ratio of sperm:egg = 50:1, and conventional methods are used for larval cultivation and adult shellfish rearing to obtain a fast-growing and high-survival rate triploid Fujian oyster improved strain.

[0021] Beneficial effects of the present invention

[0022] Compared with the known technology, the technical solution provided by the present invention has the following beneficial effects

[0023] (1) The diploid Fujian oyster is genetically improved by selective breeding and hybrid breeding, and a new hybrid strain of diploid Fujian oyster with fast growth rate and high survival rate is obtained as the female parent. (2) The tetraploid Fujian oyster black shell improved strain with high and stable tetraploid rate, fast growth rate and high fertility is obtained as the male parent by group breeding and family breeding. (3) While breeding the tetraploid population, the induction experiment is repeated to add tetraploids with different genetic backgrounds into the original population to further improve the genetic diversity of the tetraploid population. (4) The present invention uses the new diploid Fujian oyster hybrid strain as the female parent and the tetraploid Fujian oyster black shell improved strain with high genetic diversity as the male parent to obtain a fast-growing and high-survival rate triploid Fujian oyster improved strain. While maintaining the high temperature resistance of Fujian oysters, the offspring has significantly improved growth rate and survival rate, which is suitable for promotion of aquaculture in southern coastal areas such as Fujian and Guangdong in my country, and has broad prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention discloses a technical roadmap for the cultivation method of a fast-growing and high-survival rate improved strain of triploid Fujian oysters. DETAILED DESCRIPTION

[0025] The present invention is further described below by means of specific examples, but is not intended to limit the present invention.

[0026] Example

[0027] a. Collect 5,000 wild diploid Fujian oysters from Putian, Fujian, and select individuals with pure gold and pure black shell colors as broodstock. Take shell height as the target trait, select 150 gold-shelled and black-shelled oysters with the largest shell height as broodstock at a selection intensity of 1.5-1.9, fertilize at a sperm:egg ratio of 50:1, and perform larval cultivation and adult oyster rearing by conventional methods to obtain diploid Fujian oyster shell gold and shell black breeding lines. Afterwards, perform group selection on the shell gold and shell black breeding lines for three consecutive generations with the same breeding goals and breeding techniques to obtain diploid Fujian oyster shell gold and shell black F3 generation breeding lines.

[0028] b. After the gonads of the diploid gold and black shell F3 breeding lines matured, 100 individuals with pure shell color, shell height and total weight were selected from the two lines as hybrid parents, and two new Fujian oyster diploid hybrid lines were obtained through complete diallel hybridization.

[0029] c. From the diploid Fujian oyster shell black strain, individuals with pure black color, high shell height and total weight were selected as parents, 30 individuals with neat development, 15 million or more eggs and dark yolk color were selected as female parents, and 30 individuals with full gonads and vigorous sperm were selected as male parents, and sperm and eggs were obtained by "dry stripping method". Fertilization was carried out at a ratio of sperm:egg = 50:1, and 0.75 mg / L cytochalasin B was added 15 minutes after fertilization to inhibit the release of the second polar body of the fertilized egg. After continuous treatment for 15 minutes, the fertilized eggs were soaked in 2 mg / L dimethyl sulfoxide solution and seawater, and the ploidy of the larvae was determined after hatching and selection. The group with a triploid rate of more than 95% was retained, and the larvae were cultured and grown into adult shells by conventional methods to obtain the induced triploid Fujian oyster shell black strain.

[0030] d. Select 50 individuals with neat development, ≥15 million eggs and dark yolk color from the induced triploid Fujian oyster shell black strain as the female parent, and select 50 individuals with vigorous sperm from the diploid Fujian oyster shell black strain as the male parent, and fertilize them at a ratio of sperm:egg=50:1. Add 1 mg / L cytochalasin B 8 to 10 minutes after fertilization to inhibit the release of the first polar body of the fertilized egg. Take the group without reagent as the control group. When 50% of the fertilized eggs in the control group have the first polar body, wash the eggs. After hatching and selection, determine the ploidy of the larvae, retain the group with a tetraploid rate of more than 80%, and use conventional methods to culture the larvae and grow into adult shells to obtain the induced tetraploid Fujian oyster shell black strain.

[0031] e. Select the black-shell tetraploid Fujian oysters with pure black shell color, large shell height and total weight, and high fertility as parents, select the top 10% of individuals in shell height and total weight, construct the black-shell tetraploid Fujian oyster strain, and carry out high-intensity group breeding for 2 to 3 generations, selecting more than 50 males and females in each generation.

[0032] f. Repeat step (e) to obtain black-shelled tetraploid Fujian oysters with different genetic backgrounds, and continuously add them to the original tetraploid population to ensure the high genetic diversity of the black-shelled tetraploid Fujian oyster strain.

[0033] g. Tetraploid Fujian oysters with pure black shell color, high shell height and total weight are selected as parents, and 40-50 full-sib families are established through one-to-one fertilization. After the gonads of the previous generation family mature, families with pure black shell color and a tetraploidy rate greater than 95% are selected as parents of the next generation family. Tetraploid individuals from different families are randomly fertilized one-to-one to obtain the next generation family. After 2-3 generations of family selection, the improved tetraploid Fujian oyster black shell strain with high tetraploidy rate, pure shell color and high fertility can be obtained.

[0034] h. The diploid Fujian oyster hybrid strain described in step (b) is used as the female parent, and the tetraploid Fujian oyster black improved strain described in step (g) is used as the male parent, and the fast-growing triploid Fujian oyster new strain with high survival rate is obtained by hybridization. The obtained triploid Fujian oyster new strain and the black shell, gold shell diploid and triploid control groups are transferred to the main breeding sites in Putian, Fujian for trial breeding, and the production data of each group are recorded in Table 1.

[0035] As can be seen from Table 1, the fast-growing and high-survival triploid new strain of Fujian oysters cultivated by the present invention has significant production advantages. Compared with the black-shell and gold-shell triploid control groups, its growth rate can be increased by 20-40%, the survival rate can be increased by more than 30%, and the yield can be increased by more than 90%. Compared with the black-shell and gold-shell diploid control groups, its growth rate can be increased by 104-168%, and the yield can be increased by more than 160%, which significantly improves the economic benefits of Fujian oyster farming.

[0036] Table 1 Comparison of production performance between the new fast-growing and high-survival triploid Fujian oyster strain and the control group

[0037] Shell height (mm) Wet weight (g) Survival rate (%) Yield (g) New strains 88.39 89.65 58.15 156388 Shell Black 3n 72.71 63.68 43.21 82548 Shell Gold 3N 68.99 63.1 41.89 79291.8 Shell Black 2n 43.45 33.5 32.54 32701.7 Shell Gold 2n 40.36 32.89 30.82 30414

[0038] The above description is only used to illustrate the technical solutions and features of the present invention, and is not intended to limit the protection scope of the present invention. Any simple modification or equivalent replacement of the technical solutions in the present invention by any technician familiar with the field should fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for cultivating a fast-growing, high-survival rate triploid Fujian oyster improved strain, characterized in that: The following steps are involved: a. Selecting diploid Fujian oysters with golden and black shell colors as broodstock, improving the shell color and growth traits through group breeding, and obtaining diploid Fujian oysters with golden and black shells; b. By hybridizing between selected strains, the additive genetic variance accumulated within the strains and the non-additive genetic variance between strains during the breeding process of the Fujian oyster shell gold and shell black strains were combined to obtain a new diploid Fujian oyster hybrid strain with fast growth rate and high survival rate; c. Using the diploid Fujian oyster shell black strain as the male and female parent, the triploid Fujian oyster shell black strain was induced to obtain the triploid Fujian oyster shell black strain; using the triploid Fujian oyster shell black strain as the female parent and the diploid Fujian oyster shell black strain as the male parent, the tetraploid Fujian oyster shell black strain was induced to obtain the tetraploid Fujian oyster shell black strain; d. Directed selection of the shell color, growth and fecundity of the tetraploid Fujian oyster black shell strain was carried out through group selection and family selection, so as to obtain an improved tetraploid Fujian oyster black shell strain with pure shell color, fast growth rate and high fecundity; e. Using the diploid Fujian oyster hybrid new strain described in step (b) as the female parent and the tetraploid Fujian oyster black shell improved strain described in step (d) as the male parent, hybridization can obtain a fast-growing and high-survival rate triploid Fujian oyster improved strain.

2. The method for cultivating a fast-growing, high-survival rate triploid Fujian oyster improved strain according to claim 1, characterized in that: In step (a), oysters with good vitality, beautiful and undamaged shells, and pure gold or pure black shells on both sides are selected as broodstock for the two basic groups. When performing group selection, the top 10% of individuals in terms of shell height and wet weight are selected, and high-intensity selection is continued for 3 to 4 generations.

3. The method for cultivating a fast-growing, high-survival rate triploid Fujian oyster improved strain according to claim 1, characterized in that: In step (b), when hybridization is performed, individuals with high shell height and total weight are preferred, and at least 50 male and female parents are selected from the black shell and gold shell strains, respectively, and fertilized at a ratio of sperm:egg=50:

1.

4. The method for cultivating a fast-growing, high-survival rate triploid Fujian oyster improved strain according to claim 1, characterized in that: In step (c), the triploid Fujian oyster shell black strain is induced, and individuals with pure black color, high shell height and total weight are selected from the diploid Fujian oyster shell black strain as parents, among which, individuals with neat development, 15 million or more eggs and dark yolk color are preferred as female parents, and individuals with full gonads and vigorous sperm motility are preferred as male parents, and sperm and eggs are obtained by the "dry stripping method".

5. The method for cultivating a fast-growing, high-survival rate triploid Fujian oyster improved strain according to claim 1, characterized in that: In step (c), the triploid Fujian oyster black shell strain is induced, and 0.75 mg / L cytochalasin B is added 15 minutes after fertilization to inhibit the release of the second polar body. After continuous treatment for 15 minutes, the fertilized eggs are immersed in 2 mg / L dimethyl sulfoxide solution and seawater. After hatching and selection, the ploidy of the larvae is determined, and the group with a triploid rate of more than 95% is retained. The larvae are cultured and grown into adult shells using conventional methods to obtain the triploid Fujian oyster black shell induced strain.

6. The method for cultivating a fast-growing, high-survival rate triploid Fujian oyster improved strain according to claim 1, characterized in that: In step (c), the tetraploid Fujian oyster shell black strain is induced, and individuals with neat development, 15 million eggs or more, and dark yolk color are selected from the triploid Fujian oyster shell black strain as the female parent, and individuals with vigorous sperm motility are selected from the diploid Fujian oyster shell black strain as the male parent. Fertilization is carried out at a ratio of sperm:egg=50:1, and 1 mg / L cytochalasin B is added 8 to 10 minutes after fertilization to inhibit the release of the first polar body of the fertilized egg. The group without reagent is used as the control group. When the first polar body appears in 50% of the fertilized eggs in the control group, the eggs are washed, and the ploidy of the larvae is determined after hatching and selection. The group with a tetraploid rate of more than 80% is retained to obtain the tetraploid Fujian oyster shell black induced strain.

7. The method for cultivating a fast-growing, high-survival rate triploid Fujian oyster improved strain according to claim 1, characterized in that: In step (d), when performing population breeding, the black-shell tetraploid Fujian oyster with pure black shell color, large shell height and total weight, and high fertility is preferably used as the parent, and the top 10% of individuals in terms of shell height and total weight are selected. More than 50 males and females are selected in each generation, and high-intensity breeding is continued for 2 to 3 generations.

8. The method for cultivating a fast-growing, high-survival rate triploid Fujian oyster improved strain according to claim 1, characterized in that: In step (d), when population selection is carried out, step (c) is repeated to obtain black-shelled tetraploid Fujian oysters with different genetic backgrounds, which are continuously added to the original tetraploid population to ensure high genetic diversity of the tetraploid population.

9. The method for cultivating a fast-growing, high-survival rate triploid Fujian oyster improved strain according to claim 1, characterized in that: In step (d), when performing family selection, tetraploid Fujian oysters with pure black shell color, shell height and total weight are preferably used as parents, and 40-50 full-sib families are established by one-to-one fertilization. After the gonads of the previous generation family mature, families with pure black shell color and a tetraploid rate greater than 95% are preferably used as parents of the next generation family. Tetraploid individuals from different families are randomly fertilized one-to-one to obtain the next generation family. After 2 to 3 consecutive generations of family selection, a tetraploid Fujian oyster black shell improved strain with a high tetraploid rate, pure shell color and high fertility can be obtained.

10. The method for cultivating a fast-growing, high-survival rate triploid Fujian oyster improved strain according to claim 1, characterized in that: In step (e), individuals with neat development, 15 million or more eggs and dark yolk color are selected from the diploid Fujian oyster hybrid new strain as the female parent, and individuals with pure black shell color and vigorous sperm are selected from the tetraploid Fujian oyster black shell improved strain as the male parent. Fertilization is carried out at a ratio of sperm:egg = 50:1, and conventional methods are used for larval cultivation and adult oyster rearing to obtain a fast-growing and high-survival rate triploid Fujian oyster improved strain.

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