A method for breeding a fast-growing strain of rock oysters

Abstract

The present invention provides a method for breeding a fast-growing strain of rock oysters. The method comprises the following steps: (1) taking shell height and total weight as target traits, retaining broodstock with high selection intensity as a breeding base population; (2) selecting oysters with larger shell height and total weight from the previous generation breeding line as broodstock, and breeding offspring by self-propagation of the population; (3) measuring and statistically analyzing the growth data and genetic parameters of the successive generation breeding line in step (2), and evaluating the breeding effect; (4) repeating steps (2) and (3) to obtain a rock oyster breeding population with improved growth rate, and using microsatellite markers to analyze the genetic diversity of the breeding population, and evaluating the sustainable breeding potential of the breeding line. The present invention genetically improves the growth traits of rock oysters through population breeding, which not only retains its excellent reproductive characteristics, but also significantly improves the growth rate and aquaculture yield of rock oysters, and promotes the industrial application of rock oysters.

Description

Technical Field

[0001] The invention belongs to the technical field of shellfish selection and breeding, and relates to a breeding method for improving the growth traits of rock oysters, in particular to a breeding method for a fast-growing strain of rock oysters. Background Art

[0002] China is the country with the largest oyster aquaculture output in the world. Among them, the long oyster is an important aquaculture economic shellfish in the northern coastal areas of my country, with an annual output accounting for about 20% of the total oyster output in my country, creating huge economic value. However, after the long oyster enters the breeding period in summer, the meat quality decreases and the soft part becomes thin, making it unable to supply the market. Therefore, in order to meet the huge consumer demand in the summer oyster market and realize the year-round supply of high-quality oysters, it is urgent to develop high-quality oysters that can maintain a delicate taste and high nutritional content in summer to supply the market.

[0003] rock oyster( Crassostrea nippona ) is naturally distributed in East Asian seas such as Japan, South Korea and China. It has the characteristics of late spawning and multiple spawning in batches. Because it can maintain its delicious taste and high glycogen content in summer, it is considered to be the best substitute for the long oyster during the summer breeding period, and has great economic value and market prospects. In recent years, with the introduction and artificial breeding of rock oysters, the breeding technology of rock oyster seedlings has basically matured, but the problem of its slow growth during the growing period has not been effectively solved. The lack of excellent strains of rock oysters not only limits its large-scale supply to the market, but also hinders the promotion of large-scale aquaculture of rock oysters.

[0004] Population selection is a classic method for selecting based on individual phenotypic values, which is simple to operate and low in cost. When the heritability of the target trait is high, population selection can obtain a large selection response in a short period of time, and the selection effect is significant, so it is widely used in shellfish breeding. In particular, in the genetic improvement work carried out on oysters, most of them have achieved significant breeding results, and their important economic traits such as growth, survival and disease resistance have been significantly improved.

[0005] Rock oysters are very popular in the market due to their unique reproductive characteristics and have great market potential. Therefore, cultivating new varieties of rock oysters with fast growth rate is of great significance for large-scale aquaculture promotion. Summary of the invention

[0006] The purpose of the present invention is to provide a method for breeding a fast-growing strain of rock oysters, which genetically improves the growth traits of rock oysters through population breeding, so as to increase the growth rate and aquaculture yield of rock oysters and increase the economic benefits of rock oyster aquaculture.

[0007] In order to achieve the above object, the specific technical solution adopted by the present invention is:

[0008] A method for breeding a fast-growing strain of rock oysters, characterized by comprising the following steps:

[0009] (1) With shell height and total weight as target traits, broodstock were selected from the introduced wild rock oysters from Japan with high selection intensity as the breeding base population for establishing the breeding line;

[0010] (2) After the gonads of the previous generation of selected breeding lines have matured, a certain number of oysters with the largest shell height and total weight are selected as broodstock, and the offspring are bred by shade drying stimulation and group self-propagation to be used for the establishment of the next generation of selected breeding lines;

[0011] (3) measuring and statistically analyzing the growth traits and genetic parameters of the successive breeding lines in step (2) to evaluate the breeding effect;

[0012] (4) Repeat steps (2) and (3) to obtain a breeding population of rock oysters with improved growth rate. Use highly polymorphic microsatellite markers to analyze the changes in genetic diversity of the successive breeding populations and estimate the sustainable breeding potential of the breeding line.

[0013] Furthermore, in step (1), Japanese wild rock oysters with a shell height greater than 18 cm and a total weight greater than 400 g are selected as broodstock with high selection intensity to establish a breeding base population for establishing a breeding line.

[0014] Furthermore, in step (2), after the gonads of the previous generation breeding line have matured, 80 to 100 individuals with the largest shell height and total weight are selected as broodstock at a selection intensity of 1.6 to 1.9, and are placed in a cool and ventilated place to dry for 5 hours. They are then returned to the water to stimulate the natural release of sperm and eggs, thereby completing the offspring cultivation for the establishment of the next generation breeding line.

[0015] Furthermore, in step (3), the shell height and total weight of each generation of the selected breeding line and its corresponding control group are regularly measured and compared, and the genetic parameters of the growth traits of the selected breeding line are estimated to evaluate the breeding effect.

[0016] Furthermore, in step (4), 15 highly polymorphic microsatellite markers, including MK078320, MK078324, MK078328, MK078334, MK078340, MK078341, MK078342, MK078343, MK078344, MK078347, MK078350, MK078351, MK078352, MK078355 and MK078356, are used to analyze the genetic diversity of the successive breeding population through PCR amplification to estimate the continuous breeding potential of the breeding line.

[0017] Furthermore, the PCR reaction system is 10 μL, specifically 100 ng template DNA, 10×PCR buffer, 0.2 mM dNTP mixture, 1 μM primer, 1~2 mM MgCl2 and 0.25U Taq DNA polymerase. The PCR reaction conditions are 94°C pre-denaturation for 3 min; 94°C denaturation for 30 s, 60°C annealing for 1 min, 72°C extension for 1.5 min, a total of 35 cycles; 72°C extension for 5 min, and 4°C storage.

[0018] Beneficial effects of the present invention: The present invention uses a population breeding method to genetically improve the growth traits of rock oysters, and significantly improves the growth rate of rock oysters without changing the delicate taste and high glycogen content of rock oysters in summer, improves the economic benefits of rock oyster farming, and promotes large-scale artificial breeding of rock oysters. In addition, the present invention also uses highly polymorphic microsatellite markers to analyze the genetic diversity of the rock oyster breeding population, timely evaluates the continuous breeding potential and inbreeding accumulation of the breeding line, and further ensures the smooth progress of breeding work. DETAILED DESCRIPTION

[0019] The present invention is further explained and illustrated by means of specific examples below.

[0020] Example:

[0021] A method for breeding a fast-growing strain of rock oysters comprises the following steps:

[0022] (1) With shell height and total weight as target traits and a selection intensity of 1.31, individuals with a shell height greater than 19.84 cm and a total weight greater than 453.61 g were selected from the introduced wild Japanese rock oysters as broodstock to establish a basic breeding population for the establishment of a breeding line.

[0023] (2) After the gonads of the previous generation of breeding lines have matured, 80 to 100 oysters with the largest shell height and total weight are selected as broodstock at a selection intensity of 1.6 to 1.9. The broodstock with mature gonads are placed in a cool and ventilated place to dry for 5 hours and then returned to the water to stimulate the natural release of sperm and eggs, thus completing the offspring cultivation for the establishment of the next generation of breeding lines.

[0024] (3) Regularly measure and compile statistics on the growth traits and genetic parameters of the selected lines in step (2), and compare the growth data of the selected lines with those of the corresponding control groups to evaluate the breeding effect.

[0025] (4) Repeat steps (2) and (3) to obtain a breeding population of rock oysters with improved growth rate. Use 15 highly polymorphic microsatellite markers, including MK078320, MK078324, MK078328, MK078334, MK078340, MK078341, MK078342, MK078343, MK078344, MK078347, MK078350, MK078351, MK078352, MK078355 and MK078356, to analyze the genetic diversity of the successive breeding population by PCR amplification, and estimate the sustainable breeding potential of the breeding line.

[0026] Practice has shown that the growth traits of rock oysters have been significantly improved through group breeding. By comparing the growth data of the selected lines and the corresponding control groups at 780 days of age, it was found that the growth traits of the selected rock oyster population were significantly higher than those of the control group. The shell height of the selected lines was 12-21% higher than that of the control group on average, and the total weight of the selected lines was 13-17% higher than that of the control group on average.

[0027] 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 breeding a fast-growing strain of rock oysters, characterized in that: The method comprises the following steps: (1) With shell height and total weight as target traits, wild rock oysters with shell height greater than 18 cm and total weight greater than 400 g were selected from wild rock oysters with a selection intensity of 1.31 as broodstock and used as the breeding base population to establish the breeding line; (2) After the gonads of the previous generation of breeding lines mature, 80 to 100 oysters with the largest shell height and total weight are selected as broodstock at a selection intensity of 1.6 to 1.

9. They are placed in a cool and ventilated place to dry for 5 hours and then returned to the water to stimulate the natural release of sperm and eggs, completing the offspring cultivation for the establishment of the next generation of breeding lines; (3) measuring and compiling statistics on the growth data and genetic parameters of the successive breeding lines in step (2) to evaluate the breeding effect; (4) Repeat steps (2) and (3) to obtain a rock oyster breeding population with improved growth rate. Use 15 highly polymorphic microsatellite markers, including MK078320, MK078324, MK078328, MK078334, MK078340, MK078341, MK078342, MK078343, MK078344, MK078347, MK078350, MK078351, MK078352, MK078355 and MK078356, to analyze the genetic diversity of the successive breeding population by PCR amplification, and estimate the sustainable breeding potential of the breeding line.

2. The breeding method according to claim 1, characterized in that: In the step (3), the growth data of shell height and total weight of each generation of breeding lines and corresponding control groups are regularly measured and compared, and the genetic parameters of growth traits of the breeding lines are estimated to evaluate the breeding effect.