CN112119948A

CN112119948A - Subfamily distant hybridization method for bighead carp and megalobrama amblycephala

Info

Publication number: CN112119948A
Application number: CN202010921674.0A
Authority: CN
Inventors: 刘少军; 王余德; 罗亚新; 姚家俊; 谭慧芳; 赵如榕; 罗凯坤; 覃钦博; 张纯; 陶敏; 汤陈宸
Original assignee: Hunan Normal University
Current assignee: Hunan Normal University
Priority date: 2020-09-04
Filing date: 2020-09-04
Publication date: 2020-12-25

Abstract

The invention discloses a subfamily distant hybridization method for bighead carp and megalobrama amblycephala, which comprises the following steps: artificial induced spawning is carried out by taking bighead carp as a female parent and megalobrama amblycephala as a male parent, wherein an induced spawning agent PG or LRH-A is injected into female parent fish at first, and the injection is carried out on male parent fish at the same time, so that the dosage is reduced by half; injecting mixed oxytocic consisting of LRH-A, PG and HCG into the female parent fish after 3-4 h; and performing artificial dry insemination on the ovum and the sperm obtained after artificial parturition induction, then hatching the fertilized ovum in running water, and obtaining the filial generation of the bighead carp and the megalobrama amblycephala after successful hatching. The obtained new filial generation provides new resources and basis for the genetic breeding of freshwater fish, the whole hybridization process is simple to operate, the breeding period is short, the hatching rate and the survival rate of the filial generation are high, and the method has important significance in the aspects of heritage breeding and industrialization.

Description

Subfamily distant hybridization method for bighead carp and megalobrama amblycephala

Technical Field

The invention belongs to the field of fish hybridization, particularly relates to the field of hybridization among subfamilies of fishes, and particularly relates to a subfamily distant hybridization method for bighead carp and megalobrama amblycephala.

Background

There are more than 32000 fishes in the world, which are the most diverse groups of vertebrates; wherein, the food habits of most fishes are the food habits of miscellaneous food or meat; only 3 herbivorous fishes were found, which were megalobrama amblycephala, grass carp and mullet, respectively. The feed for herbivorous fishes is from the nature and belongs to a vegetable protein source, so that the green ecological breeding value of the herbivorous fishes is more and more valued. Distant hybridization refers to the hybridization of species, genus and even more distant species of organisms, and is considered to be an effective way to promote adaptive radiation evolution and speciation in animals and plants. Distant hybridization can result in changes in genomic gene function, chromosomal structure, and genome size, which can result in the transfer of a genome from one species to another, resulting in an altered phenotype of the progeny of the cross. Genotypically, distant crosses can result in alterations in offspring at the genomic level, thereby producing diploid, triploid, tetraploid offspring. In the aspect of phenotype, distant hybridization can integrate the advantages of parents, so that the filial generation shows heterosis in the aspects of appearance, growth speed, survival rate, disease resistance and the like. The hybridization method provides valuable resources for the subsequent breeding of novel polyploid fish, and has important biological significance in biological evolution and fish genetic breeding.

However, the long-term problems in the field of distant hybridization are that the survival rate of the bred offspring is low, the segregation of the hybrid traits is large, and the stability is not easy. Therefore, how to utilize and improve the existing biotechnology method to select suitable parent fishes from the existing fishes for distant hybridization so as to genetically improve the fishes to obtain novel fishes with better characters, more abundant varieties and more significance for genetic breeding research becomes a problem which is faced and needed by the technicians in the field for a long time.

Compared with other types of fish, bighead carp (Hypophthalmichthys nobilis) has a flat and high body, a rounded abdomen before the base of the ventral fin, and a narrow ventral ridge from the back to the front of the anus; the head is extremely large, the front part is wide, and the head length is greater than the body height; the fertilizer grows in freshwater lakes, rivers, reservoirs and ponds and is mostly distributed on the middle and upper layers of freshwater areas; the fish is warm water fish, the water temperature suitable for growth is 25-30 ℃, the fish can adapt to a relatively fertile water environment, and the fish has the excellent characteristics of strong stress resistance, water purification, good meat quality, high amino acid content and the like. The Megalobrama amblycephala (Megalobrama amblycephala) has high body height, the whole body is in a rhombus shape, the body length is about 50cm, and the body height is 2.2-2.8 times; the back of the body is grey, the two sides are silver grey, and the abdomen is silvery white; the base part of the body-side scale is grey white, and the edge of the body-side scale is grey black, so that grey-white alternate stripes are formed; the body is flat and high, is rhombic, has a small head, and has the advantages of rapid rise of the back and the head, high growth speed, hypoxia resistance, rich nutrition and the like. If distant hybridization is carried out on bighead carp and megalobrama amblycephala, a filial generation fish integrating the advantages of two parents is expected to be cultivated. However, the bighead carp and the megalobrama amblycephala do not live in the same water area, the breeding cycle is asynchronous, the living water environment is different, the filial generation is difficult to obtain smoothly by the conventional method, even if the filial generation can be obtained, the incubation rate, the hatching rate and the survival rate of the filial generation are low, and the industrial popularization is difficult to realize.

Disclosure of Invention

The technical problem to be solved by the invention is to overcome the defects and shortcomings in the background technology and provide a method for distant hybridization between bighead carp and megalobrama amblycephala subfamilies.

In order to solve the technical problems, the technical scheme provided by the invention is as follows:

a method for subfamily distant hybridization of bighead carp and megalobrama amblycephala comprises the following steps: the artificial induced spawning method is characterized in that bighead carp is used as a female parent, megalobrama amblycephala is used as a male parent, an oxytocic is injected into female parent fish by adopting a two-needle injection method, an oxytocic is injected into male parent fish by adopting a one-needle injection method, firstly, the female parent fish is injected with 0.5-1mg/kg of pituitary gland or 1-2 mug/kg of luteinizing hormone releasing hormone analogue (the female parent fish is injected with a first needle), and the oxytocic which is the same as that of the female parent fish is injected into the male parent fish, wherein the dosage is halved compared with that of the female parent fish; injecting mixed oxytocic comprising luteinizing hormone releasing hormone analog 10-15 μ g/kg, pituitary gland 1-2mg/kg and chorionic gonadotropin 800-; and performing artificial dry insemination on the ovum and the sperm obtained after artificial parturition induction, then hatching the fertilized ovum in running water, and obtaining the filial generation of the bighead carp and the megalobrama amblycephala after successful hatching.

The invention adopts specific oxytocic types, dosage and injection mode, can accelerate gonad maturation, shorten the oxytocic time and improve the oxytocic efficiency. Wherein, the luteinizing hormone releasing hormone analogue (LRH-A) can promote the oestrus and oviposition of the parent fish, the chorionic gonadotropin (HCG) can not only promote the ovulation of the parent fish, but also accelerate the gonad maturation, and the combined use with Pituitary (PG) can shorten the spawning induction time and improve the spawning induction efficiency. Through long-term systematic groping, the method adopts a two-needle injection method for induced spawning when the bighead carp is induced to spawn, which is beneficial to obtaining a large amount of high-quality ova, and simultaneously adjusts the induced spawning dosage of the megalobrama amblycephala, which is beneficial to achieving the maximum induced spawning rate and improving the hatching rate and the survival rate of filial generations.

Preferably, before artificial induced spawning, in the last 3 months of the year, female bighead carps and male megalobrama amblycephala with obvious mature characteristics, no diseases or injuries and good physical signs are selected as female parent fishes and male parent fishes respectively and are placed in a special pond for cultivation, and the gonads of the parent fishes are promoted to mature by using running water every 1-3 days 1 month before induced spawning.

The water quality index for feeding male megalobrama amblycephala is as followsThe following: pH of 7.0-7.4, hardness of less than 15 deg.C, and iron ion concentration of 3 × 10^-7Less than mol/L, sulfate ion concentration < 1.5X 10^-5mol/L, chloride ion concentration < 1.9X 10^-5mol/L, free chlorine and other toxic and harmful substances are not contained, the dissolved oxygen is more than or equal to 5mg/L, the ammonia concentration is less than 1 multiplied by 10^-7mg/L, nitrite concentration < 1X 10^- ⁷mol/L, nitrate concentration at 5.5X 10^-6mg/L-6.0×10^-6mg/L, hydrogen sulfide free; the water quality index for feeding female bighead carp is as follows: the pH value is 6.5-8.5, the dissolved oxygen is more than or equal to 5mg/L, the ammonia nitrogen content is less than 0.025mg/L, and the biochemical oxygen demand is less than 5 mg/L.

Preferably, in the last 6 th of the year, when the water temperature is stabilized at 22-25 ℃, selecting female bighead carps with swollen, soft and elastic abdomens from parent fishes as female parents and male megalobrama amblycephala capable of squeezing milky semen by lightly pressing abdomens as male parents to artificially hasten parturition.

Preferably, the abdominal cavity at the base of the pectoral fin of the parent fish without scales is injected during artificial induction.

Preferably, after the female parent fish and the male parent fish are injected with the oxytocic, the parent fish is placed in the same spawning pond according to the quantity ratio of female fish to male fish of 2-3:1 to wait for spawning and sperm production; the water surface area of the spawning pond is 12-15m²。

Preferably, the specific operation of artificial dry insemination comprises the following steps: wiping off water covered on the body surfaces of the male parent fish and the female parent fish, squeezing semen and ovum into a dry fertilization basin, simultaneously rapidly stirring with feathers to avoid direct irradiation of sunlight, uniformly splashing in an incubation tank after stirring for 2-3min, and incubating with running water.

Preferably, the water temperature is controlled to be 22-25 ℃ when the fertilized eggs are incubated in running water. The invention adopts the novel fish floating egg hatching device to hatch in running water, and the running water hatching has the advantages that: 1) the water is continuously supplemented, and the water quality and the oxygen demand are ensured to be not less than 5 mg/L; 2) after the fry is taken out of the membrane, the egg membrane can be conveniently and timely removed, and the water quality is prevented from being polluted; 3) the hatched seedlings have stronger vitality and high survival rate.

Preferably, the fry obtained by the running water hatching is continuously cultured in a hatching tank for 2-4 days, the fry is transferred to a pond with pre-fertilization for fine breeding after waist spots appear, soybean milk is splashed for 1-2 times every day after the fry is placed in the pond, round algae are placed in the pond, and the feed powder is fed after the fry grows to 5-8 cm.

Preferably, the diploid bighead bream is obtained after detection and screening of filial generations of the bighead carp and the megalobrama amblycephala, and the detection and screening method comprises shape measurement, a flow cell DNA content method, a blood smear method, a blood cell morphology identification method and a chromosome slide making method.

Compared with the prior art, the invention has the beneficial effects that:

1. the method of the invention solves the problem of difficult distant hybridization between the bighead carp and the megalobrama amblycephala, adopts the specific mixed oxytocic, injects the mixed oxytocic into the parent fish body with proper dosage to induce spawning, obviously increases the hatching rate, provides the greatest possibility in quantity for screening the offspring of various hybrid varieties, integrates the excellent characters of the bighead carp and the megalobrama amblycephala, enriches the varieties of fishes in the market, lays a good foundation for the breeding of the excellent varieties, provides valuable resources for the subsequent breeding of novel polyploid fishes, and has important biological significance in biological evolution and fish inheritance.

2. Compared with parents, the filial generation diploid bighead bream has obvious hybridization characteristics, integrates the excellent characteristics of the parents, improves the edible value, and has high growth speed and obviously enhanced disease resistance.

3. The diploid bighead bream has the characteristic of herbivory, germplasm resources of herbivorous fishes are increased, and the herbivorous fishes are sourced from the nature and belong to vegetable protein sources, so that the green ecological breeding value of the herbivorous fishes is more and more emphasized, and the diploid bighead bream has important application value in production.

4. According to the diploid bighead bream obtained by the hybridization method, the separation of parent chromosome groups in filial generations can effectively reduce the phenomenon of incompatibility of genetic materials and improve the survival rate of the filial generations from the perspective of genetic stability; meanwhile, the hybridization method provides a means for obtaining the bighead bream in a large scale, and enriches a parent source of other hybridization combinations.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a shape diagram of diploid bighead bream in male and female filial generations of bighead bream;

FIG. 2 is a test diagram of diploid bighead bream breeding in male and female filial generations of bighead bream;

FIG. 3 is a graph showing DNA content of diploid bighead bream in male and female filial generations of bighead bream;

FIG. 4 is a diagram of diploid bighead bream blood cells in male and female filial generations of bighead bream;

FIG. 5 is a chromosome map of diploid bighead bream in male and female filial generations of bighead bream.

Detailed Description

In order to facilitate understanding of the invention, the invention will be described more fully and in detail with reference to the accompanying drawings and preferred embodiments, but the scope of the invention is not limited to the specific embodiments below.

Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.

Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.

Example 1:

a method for subfamily distant hybridization of bighead carp and megalobrama amblycephala comprises the following steps:

(1) at the beginning of 3 months in the current year, pulling a net and fishing, selecting female bighead carps and male megalobrama amblycephala which have obvious sexual maturity characteristics, no diseases and injuries and good physical signs from the female bighead carps and the male megalobrama amblycephala as parents for distant hybridization, putting the parents in a special pond for cultivation, constantly paying attention to keeping the water quality of a water body good and the oxygen content in the water sufficient during the cultivation period, ensuring that the parents in the breeding period have a good state, well performing the work of feeding management, and stimulating the parents with running water every day in the month before the breeding period so as to promote the gonads of the parent fishes to mature;

(2) selecting female bighead carps with enlarged, soft and elastic abdomens as female parents and male megalobrama amblycephala capable of extruding milky semen by slightly pressing abdomens as male parents from the parent fishes obtained in the step (1) to perform artificial induced spawning when the water temperature is stabilized above 20 ℃ and is optimal at 22-25 ℃ in the middle ten days of the current year, specifically, injecting an oxytocic into the female parent fishes by adopting a two-needle injection method, injecting an oxytocic into the male parent fishes by adopting a one-needle injection method, firstly injecting the oxytocic PG 1mg/kg or LRH-A1 mu g/kg into the female parent fishes, and simultaneously injecting the male parent fishes by adopting the oxytocic same as the female parent fishes, wherein the dosage is halved compared with that of the female parent fishes; performing second injection on the female parent fish after 3h, and injecting a mixed oxytocic consisting of LRH-A15 mug/kg, PG 2mg/kg and HCG 1000IU/kg to the female parent fish; after injection is finished, putting the female parent fish and the male parent fish in the same spawning pond according to different proportional quantities, so that the parent fish can be observed to spawn conveniently, generally, after the injection is finished for 6-7h, the phenomenon of chasing of the female and male fishes can be found, immediately pulling a net for inspection, slightly pressing the abdomen of the female parent, enabling an egg particle source to flow out, simultaneously selecting the corresponding male parent, and preparing for artificial insemination as soon as possible.

(3) Selecting female parent fish which can lay eggs smoothly and male parent fish which can produce high precision from the female parent fish and the male parent fish obtained in the step (2) to carry out artificial dry insemination, ensuring that the body surface of the parent fish does not cover a large amount of water body as much as possible during insemination, extruding the precision and the eggs into a dry fertilization basin, simultaneously rapidly stirring by using feathers to avoid direct irradiation of sunlight, and uniformly splashing the mixture in a hatching tank after stirring for 2-3 min; and placing the obtained fertilized eggs in a hatching tank with the water temperature of about 22 ℃ to continuously perform running water hatching to obtain the fry of the filial generation of the bighead carp and the megalobrama amblycephala.

(4) Placing the fry of the filial generation obtained by incubation culture in an incubation tank for continuous culture for 3 days, after the fry of the filial generation has a waist point, transferring the fry into a cement pond which is fertilized with soybean milk in advance for feeding, splashing the soybean milk twice a day into the cement pond after the fry is placed, placing the spirulina to ensure the nutrition supply of the fry, and feeding the feed powder after the fry grows to 5-8 cm; and then detecting and screening the fed offspring by adopting a shape measurement method, a flow cell DNA content method, a blood smear method, a blood cell shape identification method and a chromosome shape film making method to obtain the shape of the diploid megalobrama amblycephala shown in figure 1.

After the filial generation is bred for about 3-4 months, the related indexes of the filial generation are detected immediately and compared with the female parent Bighead carp and the male parent Megalobrama amblycephala, and the results are shown in table 1:

table 1: countable character comparison of bighead carp, megalobrama amblycephala and filial generation thereof (unit: sheet or strip)

Fish species	Side line scale	Side line scale	Side line lower scale	Back fin ray	Ventral fin ray	Hip fin ray
							Bighead carp	103-105	28-29	15-16	Ⅲ±7-8	7-8	Ⅲ±13-14
Megalobrama amblycephala	50-52	8-10	9-11	Ⅲ±8-9	8-10	Ⅲ±26-28
							Bighead bream	74-76	15-19	7-10	Ⅲ±8-10	8-9	Ⅲ±17-18

It can be seen from table 1 that the diploid bighead breams in the filial generation are between the female parent bighead breams and the male parent megalobrama breams in appearance (side line scales, dorsal fin lines, pectoral fin lines, ventral fin lines and gluteal fin lines), and have obvious hybridization characteristics.

Table 2: quantitative property comparison of bighead carp, megalobrama amblycephala and filial generation thereof

Fish species

Body length/full length

Height/length of body

Head length/body length

Height/length of head

Tail handle height/tail handle length

Height of head/height of body

Bighead carp

0.65±0.09

0.31±0.01

0.43±0.04

0.70±0.05

0.13±0.10

0.96±0.01

Megalobrama amblycephala

0.84±0.06

0.53±0.05

0.23±0.07

0.88±0.04

1.03±0.04

0.58±0.05

Bighead bream

0.80±0.01

0.31±0.01

0.29±0.01

0.79±0.04

0.73±0.07

From the quantitative characters in table 2, it is found that the quantitative characters of the diploid bighead bream are all between that of the female parent bighead bream and that of the male parent megalobrama amblycephala, and the diploid bighead bream has obvious hybridization characteristics.

The breeding test chart of diploid bighead bream in the filial generation is shown in figure 2, and the breeding test shows that the hybrid fish has the characteristics of high growth speed, strong disease resistance, purified water quality and herbivory.

The filial generation of the bighead carp and the megalobrama amblycephala is detected and screened:

the female parent of bighead bream and the male parent of megalobrama amblycephala are used as a control, the DNA content of the diploid bighead bream is measured by a flow cytometer, as shown in figure 3, the DNA content is 54.88, and therefore, the filial generation is the diploid fish. To identify the nuclear differential morphology of these several fish, we prepared blood smears, as shown in fig. 4, and by comparison we found that the nuclei of diploid megalobrama amblycephala and diploid megalobrama amblycephala were of identical size. And detecting the number of chromosomes of the somatic cells of the filial generations of the female parent bighead carp and the male parent megalobrama amblycephala by using a peripheral blood cell slide making method, wherein the number of chromosomes of the filial generations is found to be 48 through counting, so that the filial generations are proved to be diploid.

Flow cytometry DNA content determination: wiping the vein part of the tail of the experimental fish clean by using a complexing iodine gauze, collecting about 0.2mL of blood from the vein part of the tail of the experimental fish by using a 1mL disposable syringe wetted by an anticoagulant, injecting the blood into an Eppendorf tube, adding a sample to be detected into a new Eppendorf tube by using a pipette, diluting the sample to be detected to be reddish, then adding 500 microliters of cell nucleus extracting solution DAPI-A, and reacting for 10-15min under the condition of keeping out of the sun. The sample was then filtered through a 20 μm nylon filter and finally tested on the machine.

The blood smear method comprises the following steps: the tail vein site was swabbed with 75% alcohol using a cotton swab, 0.5mL of blood was taken using a 1mL disposable syringe wetted with anticoagulant, injected into an Eppendorf tube which was sterile dried and filled with anticoagulant, and 10 microliters of blood was dropped on one side of the slide using a pipette. A new sterile slide is taken and pressed at 45 degrees onto the blood and quickly pushed to one end of the slide, so that the blood drops are uniformly spread on the slide to form a straight line. Drying in air, and dripping Wright staining solution (6-8 drops) to cover the smear with the staining solution; and after dyeing for 1min, adding a phosphate buffer solution, continuing to dye for 10min, finally flushing the back of the glass slide with running water, naturally drying in the air, and performing microscopic examination.

Chromosome ploidy assay for peripheral blood cell culture: the medium was prepared in a clean bench, 100mL of medium containing the following components: 84mL RPMI-1640, 15mL calf serum, 2 pieces PHA, 1mL 0.1% heparin sodium, with 7.5% NaHCO₃(sterile) or NaCl to pH 7.2-7.4. And (3) sucking a small amount of sterilized heparin sodium solution by using a syringe, and taking blood from the tail vein of the experimental fish after being sterilized by iodine tincture. Adding anticoagulant into 10mL culture solution according to the standard of adding 0.2mL anticoagulant into the culture solution, culturing for 68-72h in an incubator with 24 ℃ and 5% carbon dioxide concentration, and periodically and lightly shaking during the culture period to ensure that the cells are fully contacted with the culture medium. 24h before terminating the culture, 10. mu.g/mL colchicine was added dropwise to the culture medium using a 1mL syringe to a final concentration of 0.05-0.07. mu.g/mL. The above steps all need aseptic operation. The culture of the hybrid fish is taken, treated and then transferred into a sterile and clean 10mL centrifuge tube, centrifuged for 5min at 1500rpm, and the supernatant is discarded. Adding 5mL of hypotonic solution into the centrifuge tube, gently blowing and beating the mixture by using a suction tube to uniformly mix the mixture, adding the mixture to 9mL, and performing hypotonic treatment for 45-60 min. 1mL of the stationary liquid (methanol: glacial acetic acid: about 3:1) was added, the mixture was gently pipetted and mixed by centrifugation at 1500rpm for 5min, and the supernatant was discarded. Adding 5mL of stationary liquid, mixing gently, standing for 10min, centrifuging at 1000rpm for 5min, discarding the supernatant for 24h before terminating the culture, and adding 10 μ g/mL of colchicine dropwise into the culture solution with 1mL syringe to obtain final concentration of 0.05-0.07 μ g/mL. The above steps all need aseptic operation. Finally, adding a proper amount of fixing solution according to the number of cells to prepare cell suspension (generally 1-2mL), then sucking the cell suspension, dripping the cell suspension from a height of 50cm, flattening the cell suspension, and slowly drying the cell suspension by using the outer flame of an alcohol lamp. And dyeing with Giemsa dye solution for 40-60min, washing the back of the glass slide with trickle water to remove the dye solution, naturally drying, and performing microscopic examination and photographing.

The method of the invention solves the problem of difficult distant hybridization between the bighead carp and the megalobrama amblycephala, adopts an artificial induced spawning mode and selects a specific mixed inducer, and injects the mixed inducer into the abdominal cavity of the parent fish at a proper dosage for induced spawning, thereby accelerating the gonad maturation, shortening the induced spawning time, and obviously increasing the induced spawning rate (90%) and the hatching rate (95.36%), thereby providing the greatest possibility in quantity for screening the offspring of various hybrid varieties, integrating the excellent characters of the bighead carp and the megalobrama amblycephala, enriching the market fish varieties, laying a good foundation for the breeding of the excellent varieties, and having important biological significance in biological evolution and fish genetic breeding. According to the diploid bighead bream hybrid fish obtained by the method, in the aspect of genetic stability, the separation of parent chromosome groups in filial generations can effectively reduce the phenomenon of incompatibility of genetic materials, improve the survival rate (95.36%) of the filial generations, integrate the excellent properties of the parents, and have the advantages of high edible value, high growth speed, strong disease resistance and hypoxia resistance; meanwhile, the hybridization method provides a means for obtaining the bighead bream in a large scale, and enriches a parent source of other hybridization combinations.

Claims

1. A method for subfamily distant hybridization of bighead carp and megalobrama amblycephala is characterized by comprising the following steps: using bighead carp as a female parent and megalobrama amblycephala as a male parent to perform artificial induced spawning, firstly injecting an oxytocic pituitary gland 0.5-1mg/kg or a luteinizing hormone releasing hormone analogue 1-2 mu g/kg to a female parent and simultaneously injecting a male parent and a female parent with the same oxytocic, wherein the dosage is reduced by half compared with that of the female parent and the male parent; injecting mixed oxytocic comprising luteinizing hormone releasing hormone analog 10-15 μ g/kg, pituitary gland 1-2mg/kg and chorionic gonadotropin 800-; and performing artificial dry insemination on the ovum and the sperm obtained after artificial parturition induction, then hatching the fertilized ovum in running water, and obtaining the filial generation of the bighead carp and the megalobrama amblycephala after successful hatching.

2. The method as claimed in claim 1, wherein before artificial induced spawning, in the last 3 months of the year, female bighead carp and male megalobrama amblycephala with obvious mature characteristics, no diseases and injuries and good signs are selected as female parent fish and male parent fish respectively, and are placed in a special pond for cultivation, and are stimulated by running water every 1-3 days for 1 month before induced spawning so as to promote the gonad of the parent fish to mature.

3. The method as claimed in claim 1, wherein artificial spawning is performed by selecting a female bighead carp with a swollen, soft and elastic belly as a female parent and a male megalobrama amblycephala with a milky white semen squeezed out by lightly pressing the belly from the parent fish when the water temperature is stabilized at 22-25 ℃ in the last 5 to 6 months of the year.

4. The method of claim 1, wherein the artificial incubation is performed by intraperitoneal injection into the parent fish at the base of the pectoral fin without scales.

5. The method of claim 1, wherein after the female parent fish and the male parent fish are injected with the oxytocic, the female fish and the male fish are placed in the same spawning pond according to the quantity ratio of 2-3:1, and spawning and sperm production are waited; the water surface area of the spawning pond is 12-15m²。

6. The method according to claim 1, characterized in that said specific operations of artificial dry insemination comprise the following steps: wiping off water covered on the body surfaces of the male parent fish and the female parent fish, squeezing semen and ovum into a dry fertilization basin, simultaneously rapidly stirring with feathers to avoid direct irradiation of sunlight, uniformly splashing in an incubation tank after stirring for 2-3min, and incubating with running water.

7. The method according to claim 1, wherein the temperature of the water is controlled to be 22-25 ℃ when hatching fertilized eggs in running water.

8. The method according to claim 1, wherein the fry obtained by running water hatching is continuously cultured in a hatching tank for 2-4 days, and is transferred to a pond with pre-fertilization for fine breeding after waist spots appear, soybean milk is sprinkled for 1-2 times every day after the fry is put in the pond, and the feed powder is fed after the fry grows to 5-8 cm.

9. The method according to any one of claims 1 to 8, wherein diploid bighead bream is obtained from the filial generation of the bighead bream and the megalobrama amblycephala after detection and screening, and the detection and screening method comprises a shape measurement method, a flow cytometry DNA content method, a blood smear method, a blood cell morphology identification method and a chromosome slide method.