A method for genetically improving the growth rate of an orange shell color mutant strain of an oyster

Abstract

The present invention provides a method for genetically improving the growth rate of an orange-shelled mutant strain of an oyster. The method is as follows: (1) hybridizing an unrelated fast-growing strain of an oyster with an unrelated orange-shelled oyster to produce F1 generation seedlings; (2) self-pollinating the F1 generation to breed the F2 generation; (3) selecting oyster individuals with orange shells on both sides from the F2 generation as parents to obtain an orange-shelled strain of an oyster with improved growth rate. The present invention increases the genetic diversity level of the orange-shelled mutant strain of an oyster while retaining the orange trait of the left and right shells by introducing the genetic background of the fast-growing strain of an oyster, thereby improving the growth traits of the orange-shelled mutant strain of an oyster.

Description

Technical Field

[0001] The invention relates to a breeding technology and method for Crassostrea gigas, and in particular to a genetic improvement method for the growth rate of a Crassostrea gigas orange shell color mutant strain. Background Art

[0002] Long oyster (Crassostrea gigas Giant crab ) has delicious meat and rich nutrition, and has always been loved by consumers all over the world. In addition, due to its strong adaptability to the environment, fast growth rate and low breeding cost, the long oyster has always been the most widely cultivated and produced marine shellfish in the world. Long oysters are mostly sold alive or in the form of "half-shell oysters". This form of shell sales makes its shell color an important indicator that affects consumers' choices. In the breeding practice of long oysters, we found long oyster mutants with orange shells on both sides, and used these orange shell mutants as the basic population to cultivate a new long oyster strain with stable traits and orange shells on both sides. The beautiful and consistent shell color is loved by consumers and farmers.

[0003] However, the orange-shelled oyster strain is based on a few mutant individuals that were initially discovered. After multiple generations of seed conservation, the entire population has low genetic diversity, high inbreeding levels, and significantly slower growth than other long oyster breeding strains, which limits its industrial application. Therefore, genetically improving the growth traits of the orange-shelled mutant strain of long oysters and cultivating a new strain of fast-growing orange-shelled oysters has a very broad market prospect.

[0004] Through the hybridization experiment of different shell color individuals of long oysters, we found that the inheritance of orange shell color conforms to Mendel's law of inheritance. The gene controlling orange shell color is recessive to the wild-type shell color gene, and the genotype of the orange shell color mutant of long oysters is recessive homozygous. Therefore, by constructing the hybrid F2 generation of orange shell color mutant individuals of long oysters with individuals of normal shell color with improved growth rate, the purpose of improving the genetic diversity level and growth traits of the orange shell color mutant strain of long oysters can be achieved without changing the orange trait of the orange shell color mutant strain of long oysters. Summary of the invention

[0005] The purpose of the present invention is to provide a method for improving the growth characteristics of orange shell color mutant individuals of long oysters by introducing the genetic background of long oyster fast-growing strains without changing the orange shell color characteristics.

[0006] The method for improving the growth rate of an orange shell color mutant strain of an oyster of the present invention is carried out according to the following steps:

[0007] a) Parent selection: Select 1-2 year old long oysters with shell height greater than 10 cm from the fast-growing long oyster strain as parents, and select 1-2 year old long oysters with orange shell color mutation individuals with shell height greater than 4 cm as parents;

[0008] b) F1 generation hybridization: The two parents are hybridized by artificial fertilization using the dissection method, and the offspring are cultivated according to the conventional artificial breeding method of long oysters to obtain F1 generation seedlings with normal shell color;

[0009] c) Self-pollination of F2 generation: The top 10% of individuals in the hybrid F1 generation are selected by the truncation method as parents for self-pollination, and the F2 generation individuals are produced by conventional artificial breeding of long oysters;

[0010] d) Shell color separation: select long oysters with orange shells on both sides from the F2 generation, and select the 10% of orange-shelled long oysters before growth by the truncation method as parents for breeding offspring;

[0011] e) Establishment of new strain: Using the orange-shelled long oysters in step d as parents, and cultivating progeny according to conventional artificial seedling breeding methods for oysters, a new strain of orange-shelled long oysters with improved growth rate can be obtained.

[0012] Furthermore, in the above steps b, c and e, the conventional artificial breeding method for long oysters is: the seawater temperature during the larval cultivation is 22-26 °C, the salinity is 30-32 psu, and continuous micro-aeration. The density of D-type larvae in the cultivation pond is 8-15 / ml, and the density of creeping larvae is reduced to 3-5 / ml. The water is changed once in the morning and evening, 1 / 3 to 1 / 2 each time, and 1 / 3 of the water is changed every day before the larvae have not hatched. The bait is fed after the water is changed, and the feeding amount is adjusted according to the development stage and feeding situation of the larvae, and is generally fed 2-4 times a day. In the early stage of larval cultivation, golden algae are fed, and the daily feeding amount gradually increases from 15,000-20,000 cells / ml in the early stage to 35,000-45,000 cells / ml in the later stage; after the larvae have hatched, flat algae are added to the bait, and the daily feeding amount gradually increases from 2-3,000 cells / ml to 8-10,000 cells / ml. When the larvae grow to 330–360 μm in shell length and 60–80% of them have eyespots, the oyster seedlings are collected from the substrate, which is made of scallop shells. The average amount of seedlings collected is 15–20 per piece. When the oyster seedlings grow to a shell length of 1–2 mm, they are transferred to the sea for cultivation.

[0013] In the above steps c and d, the truncation method uses shell height as the selection index and selects the top 10% of individuals in shell height as parents.

[0014] Beneficial effects of the present invention: Practice has proved that the present invention adopts the genetic background of the fast-growing strain of long oysters, and on the premise of retaining the orange shell color traits of the left and right shells, increases the genetic diversity level of the long oyster orange shell color strain, and improves the growth traits of the long oyster orange shell color mutant individuals. Compared with the unimproved long oyster orange shell color mutant individuals, the new strain obtained by the present invention retains the orange shell color traits of the left and right shells, and the growth rate is increased by more than 50%, indicating that the growth traits of the long oyster orange shell color mutant individuals have been significantly improved. The new strain obtained by the present invention is used in the expansion and promotion of the long oyster orange shell color improved varieties. DETAILED DESCRIPTION

[0015] The present invention is further explained and illustrated by the following examples.

[0016] Embodiment 1:

[0017] The method of hybridizing the orange shell color mutant strain of the long oyster with the fast-growing strain of the long oyster to improve its growth traits comprises the following steps:

[0018] a) Parent selection: The fast-growing strain of long oysters bred by Ocean University of China was used as the parent, and one-year-old long oysters with a shell height of 10-14 cm were selected as the parent, and one-year-old long oysters with orange shell color mutations with a shell height of 4-6 cm were selected as the parent;

[0019] b) F1 generation hybridization: artificial fertilization by dissection method, 50 females and 50 males are selected from each of the two parents for positive and negative diaristic hybridization, and the offspring are cultivated according to the conventional artificial breeding operation of long oysters to obtain F1 generation seedlings with normal shell color;

[0020] c) Self-pollination of F2 generation: The top 10% of individuals in shell height in the hybrid F1 generation are selected as parents by the truncation method, artificial fertilization is performed by the dissection method, and conventional artificial breeding of long oysters is performed to produce F2 generation individuals;

[0021] d) Shell color separation: select long oysters with orange shells on both sides from the F2 generation, and select the top 10% of orange shell individuals by the truncation method as parents for breeding offspring;

[0022] e) Establishment of new strain: Using the orange-shelled long oysters in step d as parents, and cultivating progeny according to conventional artificial seedling breeding methods for oysters, a new strain of orange-shelled long oysters with improved growth rate can be obtained.

[0023] Embodiment 2:

[0024] The new orange-shelled long oyster strain obtained in Example 1 was cultivated to 10 months of age, and then the growth performance was tested and compared with the unimproved orange-shelled long oyster strain and the fast-growing long oyster strain.

[0025] 100 10-month-old improved orange-shelled long oysters obtained in Example 1, 100 10-month-old unimproved orange-shelled long oysters and 100 10-month-old individuals from the long oyster fast-growing strain used in Example 1 were randomly selected for measurement and recording. From the results, it can be seen that the growth rate of the long oyster orange-shelled improved population obtained in Example 1 is slightly lower than that of the long oyster fast-growing strain, but significantly higher than that of the unimproved long oyster orange-shelled population, and the shell height is 55-60% higher than that of the unimproved orange-shelled long oysters on average, and the body weight is 54-65% higher than that of the unimproved orange-shelled long oysters on average.

[0026] The above embodiments are only for illustrating the technical concept and features of the present invention, and cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for genetically improving the growth rate of an orange shell color mutant strain of an oyster, characterized in that: The following steps are involved: a) Parent selection: 1-2 year old long oysters with shell height greater than 10 cm from the fast-growing long oyster strain were selected as parents, and 1-2 year old long oysters with orange shell color mutation individuals with shell height greater than 4 cm were selected as parents. The fast-growing long oyster strain is an artificially selected fast-growing long oyster strain with normal shell color. b) F1 generation hybridization: The two parents were hybridized by artificial fertilization using the dissection method, and the offspring were cultivated according to the conventional artificial breeding method of long oysters to obtain F1 generation seedlings with normal shell color. The conventional artificial breeding method of long oysters is: the seawater temperature during larval cultivation is 22-26 ℃ and the salinity is 30-32 psu, continuous micro-aeration; the density of D-type larvae in the culture pond is 8-15 cells / ml, and the density of creeping larvae is reduced to 3-5 / ml; the water is changed once in the morning and evening, 1 / 3 to 1 / 2 each time, and 1 / 3 of the water is changed every day before the larvae have not hatched; the bait is fed after the water is changed, and the feeding amount is adjusted according to the larval development stage and feeding conditions, and is generally fed 2-4 times a day; in the early stage of larval cultivation, golden algae are fed, and the daily feeding amount gradually increases from 15,000-20,000 cells / ml in the early stage to 35,000-45,000 cells / ml in the later stage; after the larvae have hatched, flat algae are added to the bait, and the daily feeding amount gradually increases from 2,000-3,000 cells / ml to 8,000-10,000 cells / ml; when the larvae grow to 330-360 cm long, the larvae are fed with golden algae .... μm, when 60–80% of the eyespots appear, the oyster seedlings are collected by placing the substrate, which is made of scallop shells. The average amount of seedlings collected is 15–20 per piece. When the oyster seedlings grow to a shell length of 1–2 mm, they are transferred to the sea for culture. c) Self-pollination of F2 generation: The top 10% of individuals in the hybrid F1 generation are selected by the truncation method as parents for self-pollination, and the F2 generation individuals are produced by conventional artificial breeding of long oysters; d) Shell color separation: select long oysters with orange shells on both sides from the F2 generation, and select the 10% of orange-shelled long oysters before growth by the truncation method as parents for breeding offspring; e) Establishment of new strain: Using the orange-shelled long oysters in step d as parents, and cultivating progeny according to conventional artificial seedling breeding methods for oysters, a new strain of orange-shelled long oysters with improved growth rate can be obtained.

2. The genetic improvement method according to claim 1, characterized in that: The F1 generation individuals in step b are all of normal shell color.

3. The genetic improvement method according to claim 1, characterized in that: In the step c, the truncation method is used to select the top 10% of individuals in the hybrid F1 generation for breeding the F2 generation.

4. The genetic improvement method according to claim 1, characterized in that: The shell color of the F2 generation individuals in step d is differentiated, with orange shell color: ordinary shell color ≈ 1:

3.

5. The genetic improvement method according to claim 1, characterized in that: In the step d, the truncation method is used to select the top 10% of individuals in terms of shell height from the orange-shelled long oyster population as parents.