Construction and Application of a three-line breeding system in the Peruvian scallop x Bay scallop hybrids

Abstract

The current invent relates to the construction and application of a three-line breeding system in the Peruvian scallop×bay scallop hybrids. The said three-line consists of a male sterile line, a maintainer line and a restorer line of the bay scallop×Peruvian scallop hybrids. Herein the Peruvian scallop×bay scallop hybrids are hybrids resulted from the eggs of the Peruvian scallops fertilized with sperm of the bay scallops. In constructing the three-line, male sterile individuals are selected from F.sub.1 inter-specific hybrid families and continuously backcrossed with sperm of the selling family of the sperm-providing bay scallops of the F.sub.1 hybrid to obtain a combination of male sterile line and maintainer line whose hybrid progenies are all male sterile. Then selected individuals from the male sterile line are continuously backcrossed with sperm from the selfing family of a bay scallop until the resulted progenies are all hermaphroditic and exhibit excellent production traits. Commercial male sterile brood stocks are produced by backcrossing the eggs of the male sterile line with the sperm of the maintainer line and commercial Peruvian scallop×bay scallop hybrid spats are produced by backcrossing the eggs of the male sterile line and sperm of the restorer line. This invent establishes the three-line breeding system in animals for the first time and efficiently overcomes the barrier of self-fertilization in the hybridization between hermaphroditic scallops. The yield of the hybrid scallops can be increased by over 50% compared with the bay scallops.

Claims

1. A three-line breeding system in the Peruvian scallop×bay scallop hybrids. The said three-line breeding system consisting of a male sterile line, a maintainer line and a restorer line and the said Peruvian scallop×bay scallop hybrids are progenies produced with eggs from the Peruvian scallops and sperm from bay scallops.

2. The breeding method of the three-line breeding system in claim 1 is characterized in that: 1) Production of the male sterile individuals in the Peruvian scallop×bay scallop hybrids and breeding of the male parents thereof: More than 20 F.sub.1 Peruvian scallop×bay scallop hybrid families are constructed using eggs from the Peruvian scallops and sperm from the bay scallops. The selfing family of the sperm-providing bay scallop is also produced for the selection as outlined below by fertilizing its eggs with its own sperm. 2) Breeding of the male sterile line of the Peruvian scallop×bay scallop hybrids: In the next spring, 50 individuals with excellent production traits and apparent male sterile gonad (with no obvious gonadal development in the male part of the gonad) are selected from each F.sub.1 hybrid family. Twenty bay scallops with excellent production traits are also selected from each selfing families of the corresponding sperm-providing bay scallops. Then at least 20 backcross families are constructed with the eggs from selected male sterile/female fertile individuals and sperm from selected individuals from the corresponding selfing families of the sperm-providing bay scallop. The sperm-providing bay scallop brood stocks of the backcross families are again reproduced by self-fertilization. In the following years, the male sterile/female fertile individuals from the backcross families are continuously backcrossed with individuals selected from the selfing family of the sperm-providing bay scallops, until all the individuals of the backcross progenies exhibit excellent traits and are male sterile and female fertile. The male sterile line of the Peruvian scallop×bay scallop hybrids is thus obtained. 3) Breeding of the maintainer line of the Peruvian scallop×bay scallop hybrids: The above selfing family of the sperm-providing bay scallop is able to render the male sterile characteristic to the progenies of the male sterile line and thus becomes the corresponding maintainer line for this male sterile line. 4) Breeding of the restorer line of the Peruvian scallop×bay scallop hybrids: Fifty large male sterile and female fertile individuals are selected from the male sterile line and the maintainer line respectively and conditioned to ripeness. They are then induced to spawn and the eggs from the male sterile individuals are fertilized by the sperm of different bay scallops to establish at least 20 backcross families; meanwhile, the sperm-providing bay scallops are self-fertilized to establish the corresponding self-fertilization families. At harvest, the growth and survival rates of the backcross progenies are measured and the combining ability tests are carried out for each backcross family. In the following year, excellent individuals are selected from both the male sterile line and the corresponding sperm-providing bay scallop selfing family that correlated to the best backcross family with the highest combining ability and highest percentage of hermaphroditic individuals. After conditioning and spawning induction, eggs from the male sterile line are again backcrossed with the sperm of the selected individual from the selfing family of the sperm-providing bay scallop. Same selections are carried each year on the selfing family of the sperm-providing bay scallop until all individuals in the backcross family are hermaphroditic and exhibit excellent production traits. This selfing family of the sperm-providing bay scallop becomes the restorer line for the corresponding male sterile line. 5) Reproduction of the three-line breeding system: The next generation of male sterile line is produced by backcrossing the brood stocks of the male sterile line with the sperm from the corresponding maintainer line. As the scallops of the maintainer line and restorer line are hermaphroditic animals, they are reproduced by self-fertilization.

3. Application of the said three-line breeding system in claim 1 in the production of commercial male sterile brood stocks of Peruvian scallop×bay scallop hybrids: In commercial scallop hatcheries, the next generation of male sterile brood stocks are produced by fertilizing the eggs of the male sterile line with the sperm from its corresponding maintainer line at large scales and low costs.

4. Application of the said three-line breeding system in claim 1 in the production of commercial Peruvian scallop×bay scallop hybrid spats: In commercial scallop hatcheries, the commercial Peruvian scallop×bay scallop hybrid spats are produced by fertilizing the eggs of the male sterile brood stocks with the sperm from brood stocks of its corresponding restorer line.

5-10. (canceled)

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The present invention establishes a three-line supporting breeding system, comprising a male sterile line, a maintainer line and a restorer line, of bay scallop-purple scallop hybrids and also establishes a method for producing the commercial fingerlings of the bay scallop-purple scallop hybrids by use of a three-line supporting breeding system; the specific steps are as follows:

Embodiment 1

[0024] 1) Screening of the male sterile individuals of the bay scallop-purple scallop hybrids and the breeding of the male parents thereof: in the first year, 50 gonadal maturated bay scallops and 50 purple scallops are selected; after drying in the shade and stimulus for 30 minutes, each scallop is put into an independent container to which 23° C. seawater is added in advance for spawning and spermiation; the ova of each bay scallop and the sperms and the ova of each purple scallop are collected independently; little semen from a single purple scallop is added to the ovum suspension liquid of each bay scallop and stirred so that the sperms and the ova can be mixed evenly; each ovum is surrounded by 5-6 sperms through observation under a microscope, and the fertilized ova are put in a dark environment for incubation, thereby obtaining a bay scallop-purple scallop hybrid first filial generation family. At least 20 such hybrid families are established by use of such a method; meanwhile, the sperms and the ova of the semen donating purple scallops are mixed for fertilization to establish a corresponding number of purple scallop self-fertilization families; finally, larva culture, fingerling protection and development are carried out by use of a conventional scallop breeding method for the screening of the male sterile individuals.

[0025] 2) The breeding of the male sterile line of the bay scallop-purple scallop hybrids: in the spring of the second year, the bay scallop-purple scallop hybrid first filial generation families are maturated, and then 50 male sterile individuals excellent in traits are selected and stimulated to spawn by use of a conventional purple scallop spawning induction method, and the ova are fertilized by the sperms of the male parent purple scallops thereof, respectively; the normally fertilized and developed ova are collected to establish the backcross families, and meanwhile, the sperm providing purple scallops are self-fertilized to establish the self-fertilization families, whereby at least 20 backcross families and corresponding male parent purple scallop self-fertilization families are established, and larva culture, fingerling protection and development are carried out by use of the conventional purple scallop breeding method; in the spring of the third year, after the backcross families and the purple scallop self-fertilization families are maturated, 50 male sterile individuals having excellent traits in the backcross families are selected and backcrossed with the self-fertilization progeny sperms of the male parent purple scallops thereof, and then the normally fertilized and developed ova are collected for continuously establishing the backcross families, and meanwhile, the self-fertilization families of the purple scallops are bred continuously; more than 20 backcross families having excellent traits and corresponding purple scallop self-fertilization families thereof are selectively established; afterwards, the male sterile scallops having excellent traits are selected to be backcrossed with the self-fertilization families of the male parent purple scallops thereof by use of the same method every year until all the individuals of the backcross progenies show excellent traits and are male sterile and ovum fertile; as a result, the male sterile line of the bay scallop-purple scallop hybrids is obtained.

[0026] 3) The breeding of the maintainer line of the bay scallop-purple scallop hybrids: the male parent purple scallops capable of enabling all the individuals of the backcross progenies of the male sterile individuals to be male sterile and ovum fertile are self-fertilized by use of the conventional scallop breeding method for great reproduction, thereby obtaining the maintainer line of the male sterile line of the bay scallop-purple scallop hybrids.

[0027] 4) The breeding of the restorer line of the bay scallop-purple scallop hybrids: 50 male sterile and ovum fertile large individual scallops produced from the bred male sterile line and maintainer line are selected, and maturated to spawn, and the ova are fertilized by the sperms of the different purple scallops to establish at least 20 backcross families; meanwhile, the semen donating purple scallops are self-fertilized to establish the self-fertilization families, and the growth and survival conditions of the backcross progenies are measured and the combining ability is tested; starting from the second year, the backcross families having excellent traits and containing the hermaphroditic scallops are selected according to the combining ability test result and the gonadal development conditions every year, and the breeding scallops of the male sterile line correlated to the backcross families are continuously backcrossed with the sperms of the semen donating purple scallop self-fertilization families to establish the backcross families until the backcross families all are hermaphroditic and excellent in traits; then, the semen donating purple scallop self-fertilization families are self-fertilized for multiplication, thereby obtaining the restorer line of the male sterile line of the bay scallop-purple scallop hybrids. The restorer line is used for large-scale production of the commercial fingerlings of the bay scallop-purple scallop hybrids.

[0028] 5) A method for producing the commercial fingerlings of the bay scallop-purple scallop hybrids by use of the three-line supporting breeding system: the breeding scallops of the male sterile line and the restorer line of the bay scallop-purple scallop hybrids are hybridized for multiplying the male sterile line scallops of the bay scallop-purple scallop hybrids, and meanwhile, the restorer line is multiplied through self-fertilization by use of the conventional scallop breeding method; during breeding in spring, the breeding scallops of the male sterile line and the restorer line are selected in the ratio of 5:1 and maturated; then, breeding scallops of the male sterile line are stimulated to spawn in a spawning pond, and the breeding scallops of the restorer line are stimulated to discharge semen in a bucket, and the restorer line purple scallop semen containing no ovum is obtained through filtering by use of the 500-mesh boulting cloth; the semen of the restorer line is uniformly splashed to the spawning pond and stirred immediately; a sample is taken any time for observing the fertilization condition under the microscope; the most appropriate amount of the semen added is that each ovum is surrounded by 5-6 sperms; finally, the fertilized ova are incubated by use of the conventional method and develop to obtain the commercial fingerlings of the bay scallop-purple scallop hybrids.

Embodiment 2

[0029] At the end of March in 2008, the gonadal maturated bay scallops were picked up and subjected to thermal stimulus to obtain the ova of the bay scallops; the ova of the bay scallops were fertilized by the sperms of the purple scallops to obtain the hybrid first filial generation fingerlings of the bay scallops and the purple scallops, and the fingerlings were cultured to develop. In the spring of 2009, the scallops of the hybrid first filial generation were maturated, and then scallops large in size and developed only in female parts were selected therefrom and dried in the shade for 30 minutes; next, the scallops were put into the container containing 23° C. seawater to be stimulated to spawn, and the ova were fertilized by the sperms from a plurality of purple scallops together, whereby the backcross population of the first-filial generation bay scallop-purple scallop hybrids and the purple scallops were obtained. After the backcross population was maturated in the spring of 2010, most individuals are hermaphroditic, accompanied with less than 10% of male sterile individuals.

[0030] Continuously, the male sterile individuals were backcrossed with the sperms of the self-fertilization progenies of the male parent purple scallops thereof; whereby the male sterile line (female parent)-maintainer line (male parent) combination of which the progenies were all male sterile and ovum fertile could be obtained through one-generation to multiple-generation breeding, and therefore, the male sterile line and the maintainer line could be obtained, respectively. After gonadal maturation, spawning induction was performed on the male sterile line scallops by use of a conventional purple scallop spawning induction method to obtain a large quantity of unfertilized ova, and the unfertilized ova were fertilized by the sperms of the maintainer line so that the male sterile line breeding scallops for producing the commercial fingerlings of the bay scallop-purple scallop hybrids could be obtained at a large scale.

[0031] The ova of the male sterile line scallops in the combination were fertilized by the sperms of different unrelated purple scallops to establish at least 20 backcross families, and the combining ability was tested; the families of which the progenies contain the hermaphroditic scallops were selected, and the female parent male sterile line breeding scallops thereof were continuously fertilized by the sperms of the semen donating purple scallop self-fertilization families; continuous breeding was performed according to the growth traits and the gonad development conditions until all the backcross progenies were hermaphroditic and excellent in traits, and the restorer line purple scallop families that could be fertilized to produce male sterile line progenies all hermaphroditic and excellent in traits could be obtained.

[0032] Finally, after the gonads of the obtained male sterile line breeding scallops of the bay scallop-purple scallop hybrids were maturated, a large quantity of unfertilized ova were obtained by use of the conventional purple scallop spawning induction method and fertilized by the sperms of the restorer line to produce the commercial fingerlings of the bay scallop-purple scallop hybrids at a large scale.

Embodiment 3

[0033] In the spring of 2010, the male sterile individuals in the hybrid first filial generation of the ova of the bay scallops and the sperms of the purple scallops established in 2009 were selected, and maturated and stimulated to spawn; the ova were fertilized by the sperms of the purple scallops to establish 8 backcross families, and the backcross families were cultured. In the spring of 2011, it was discovered through maturation that most individuals of all the families were hermaphroditic and the gonads of few individuals were not developed, which proved that the restorer line of the bay scallop-purple scallop hybrids could be bred by backcrossing the purple scallops with the male sterile individuals in the first filial generation of the bay scallop-purple scallop hybrids.

Embodiment 4

[0034] In 2012, after a stimulus was applied to the male sterile individuals only developed in female parts in the first filial generation families of the bay scallop-purple scallop hybrids, 20 male sterile individuals among them spawned, and the ova were backcrossed with the sperms of one individual purple scallop to successfully obtain 2 backcross families; when harvesting in the middle of November in 2012, compared with the bay scallops in the corresponding period, the shell height, the shell length and the individual weight of one backcross family were increased by 46.3%, 45.7%, 32.3% and 134.9%, respectively, and after maturation in the spring of 2013, it was discovered that the progenies of the backcross family were wall hermaphroditic; it indicated that the restorer line of the male sterile line of the bay scallop-purple scallop hybrids could be successfully bred by backcrossing the sperms of the purple scallops with the male sterile individuals; the shell height, the shell length and the individual weight of the other backcross family were increased by 28.2%, 29.5%, 16.4% and 74.0%, respectively, and after maturation in the spring of 2013, it was discovered that the progenies of the backcross family most were developed in female parts; it indicated that the male sterile line of the bay scallop-purple scallop hybrids and the maintainer line thereof could be successfully bred by backcrossing the sperms of the purple scallops with the male sterile individuals.

Embodiment 5

[0035] In 2013 and 2014, 12 hybrid first filial generation families of the ova of the bay scallops and the sperms of the purple scallops were established by use of the imported bay scallops and purple scallops, and the self-fertilization families of the semen donating purple scallops are established; according to the method of embodiment 1, the male sterile families of the bay scallop-purple scallop hybrids and the corresponding maintainer line and restorer line thereof can be bred within 1-3 years, and therefore, the commercial production of the fingerlings of the bay scallop-purple scallop hybrids is realized.

Embodiment 6

[0036] The present invention is applied to the establishment and the application of the male sterile line, the maintainer line and the restorer line of the bay scallop-purple scallop hybrids

[0037] The establishment method of the male sterile line, the maintainer line and the restorer line disclosed by the present invention is also applied to the breeding of purple scallop-bay scallop hybrids (the hybridization progenies of the ova of the purple scallops and the sperms of the bay scallops) and applied to the establishment of a large-scale production method of the commercial fingerlings of the purple scallop-bay scallop hybrids.

[0038] Firstly, the purple scallops and the bay scallops are selected to be maturated simultaneously, and stimulated to spawn and discharge semen simultaneously; the ova of the purple scallops and the sperms and ova of the bay scallops are collected, respectively; the ova of the purple scallops are fertilized by the sperms of the bay scallops to establish purple scallop-bay scallop hybrid first filial generation families for selecting the male sterile individuals; meanwhile, the sperms and ova of the bay scallops are mixed for fertilization to establish bay scallop self-fertilization families; in the second year, the male sterile individuals are selected from the purple scallop-bay scallop hybrid first filial generation families and fertilized by the sperms of the bay scallops; if the fertilized ova develop normally, the backcross families are established for continuously breeding the male sterile line, and meanwhile, the male parent bay scallops are self-fertilized for establishing the self-fertilization families; in this way, through one generation to multiple generation selection, when the backcross progenies all are male sterile, the male sterile line of the purple scallop-bay scallop hybrids and the corresponding maintainer line are obtained.

[0039] A plurality of large individual scallops in the male sterile line of the purple scallop-bay scallop hybrids are selected and simulated to spawn, and then the ova are fertilized by the sperms of a plurality of unrelated bay scallops; if the backcross families all are hermaphroditic scallops, a male sterile line-restorer line combination is obtained only through one generation selection; if the backcross families are partially hermaphroditic, the male sterile scallops are continuously backcrossed with the sperms of the corresponding bay scallop self-fertilization families to establish the backcross families, and meanwhile, the self-fertilization families of the male parent bay scallops are continuously established for next generation breeding; after one generation or multiple generation breeding, when the backcross progenies are all hermaphroditic, the restorer line of the male sterile line of the purple scallop-bay scallop hybrids is obtained.

[0040] The ova of the male sterile line of the purple scallop-bay scallop hybrids are hybridized with the sperms of the maintainer line, thereby realizing efficient, convenient and large-scale production of the male sterile breeding scallops of the purple scallop-bay scallop hybrids; the male sterile breeding scallops of the purple scallop-bay scallop hybrids are hybridized with the sperms of the restorer line to realize efficient, convenient and large-scale production of the fingerlings of the purple scallop-bay scallop hybrids.

Embodiment 7

[0041] The present invention is applied to the establishment and the application of the male sterile line, the maintainer line and the restorer line of purple scallop-Mexico Gulf scallop hybrids.

[0042] The establishment method of the male sterile line, the maintainer line and the restorer line disclosed by the present invention is also applied to the breeding of the purple scallop-Mexico Gulf scallop hybrids (the hybridization progenies of the ova of the purple scallops and the sperms of the Mexico Gulf scallops) and applied to the establishment of a large-scale production method of the commercial fingerlings of the purple scallop-Mexico Gulf scallop hybrids.

[0043] Firstly, the purple scallops and the Mexico Gulf scallops are selected to be maturated simultaneously, and stimulated to spawn and discharge semen simultaneously; the ova of the purple scallops and the sperms and ova of the Mexico Gulf scallops are collected, respectively; the ova of the purple scallops are fertilized by the sperms of the Mexico Gulf scallops to establish purple scallop-Mexico Gulf scallop hybrid first filial generation families for selecting the male sterile individuals; meanwhile, the sperms and ova of the Mexico Gulf scallops are mixed for fertilization to establish Mexico Gulf scallop self-fertilization families; in the second year, the male sterile individuals are selected from the purple scallop-Mexico Gulf scallop hybrid first filial generation families and fertilized by the sperms of the Mexico Gulf scallops; if the fertilized ova develop normally, the backcross families are established for continuously breeding the male sterile line, and meanwhile, the male parent Mexico Gulf scallops are self-fertilized for establishing the self-fertilization families; in this way, through one generation to multiple generation selection, when the backcross progenies all are male sterile, the male sterile line of the purple scallop-Mexico Gulf scallop hybrids and the corresponding maintainer line thereof are obtained.

[0044] A plurality of large individual scallops in the male sterile line of the purple scallop-Mexico Gulf scallop hybrids are selected and simulated to spawn, and then the ova are fertilized by the sperms of a plurality of unrelated Mexico Gulf scallops; if the backcross families all are hermaphroditic scallops, the male sterile line-restorer line combination is obtained only through one generation selection; if the backcross families are partially hermaphroditic, the male sterile scallops are continuously backcrossed with the sperms of the corresponding Mexico Gulf scallop self-fertilization families to establish the backcross families, and meanwhile, the self-fertilization families of the male parent Mexico Gulf scallops are continuously established for next generation breeding; after one generation or multiple generation breeding, when the backcross progenies are all hermaphroditic, the restorer line of the male sterile line of the purple scallop-Mexico Gulf scallop hybrids is obtained.

[0045] The ova of the male sterile line of the purple scallop-Mexico Gulf scallop hybrids are hybridized with the sperms of the maintainer line, thereby realizing efficient, convenient and large-scale production of the male sterile breeding scallops of the purple scallop-Mexico Gulf scallop hybrids; the male sterile breeding scallops of the purple scallop-Mexico Gulf scallop hybrids are hybridized with the sperms of the restorer line to realize efficient, convenient and large-scale production of the fingerlings of the purple scallop-Mexico Gulf scallop hybrids.

Embodiment 8

[0046] The present invention is applied to the establishment and the application of the male sterile line, the maintainer line and the restorer line of Mexico Gulf scallop-purple scallop hybrids.

[0047] The establishment method of the male sterile line, the maintainer line and the restorer line disclosed by the present invention is also applied to the breeding of the Mexico Gulf scallop-purple scallop hybrids (the hybridization progenies of the ova of the Mexico Gulf scallops and the sperms of the purple scallops) and applied to the establishment of a large-scale production method of the commercial fingerlings of the Mexico Gulf scallop-purple scallop hybrids.

[0048] Firstly, the purple scallops and the Mexico Gulf scallops are selected to be maturated simultaneously, and stimulated to spawn and discharge semen simultaneously; the ova of the Mexico Gulf scallops and the sperms and ova of the purple scallops are collected, respectively; the ova of the Mexico Gulf scallops are fertilized by the sperms of the purple scallops to establish Mexico Gulf scallop-purple scallop hybrid first filial generation families for selecting the male sterile individuals; meanwhile, the sperms and ova of the purple scallops are mixed for fertilization to establish purple scallop self-fertilization families; in the second year, the male sterile individuals are selected from the Mexico Gulf scallop-purple scallop hybrid first filial generation families and fertilized by the sperms of the purple scallops; if the fertilized ova develop normally, the backcross families are established for continuously breeding the male sterile line, and meanwhile, the male parent purple scallops are self-fertilized for establishing the self-fertilization families; in this way, through one generation to multiple generation selection, when the backcross progenies all are male sterile, the male sterile line of the Mexico Gulf scallop-purple scallop hybrids and the corresponding maintainer line thereof are obtained.

[0049] A plurality of large individual scallops in the male sterile line of the Mexico Gulf scallop-purple scallop hybrids are selected and simulated to spawn, and then the ova are fertilized by the sperms of a plurality of unrelated purple scallops; if the backcross families all are hermaphroditic scallops, the male sterile line-restorer line combination is obtained only through one generation selection; if the backcross families are partially hermaphroditic, the male sterile scallops are continuously backcrossed with the sperms of the corresponding purple scallop self-fertilization families to establish the backcross families, and meanwhile, the self-fertilization families of the male parent purple scallops are continuously established for next generation breeding; after one generation or multiple generation breeding, when the backcross progenies are all hermaphroditic, the restorer line of the male sterile line of the Mexico Gulf scallop-purple scallop hybrids is obtained.

[0050] The ova of the male sterile line of the Mexico Gulf scallop-purple scallop hybrids are hybridized with the sperms of the maintainer line, thereby realizing efficient, convenient and large-scale production of the male sterile breeding scallops of the Mexico Gulf scallop-purple scallop hybrids; the male sterile breeding scallops of the Mexico Gulf scallop-purple scallop hybrids are hybridized with the sperms of the restorer line to realize efficient, convenient and large-scale production of the fingerlings of the Mexico Gulf scallop-purple scallop hybrids.