Application of SNP (Single Nucleotide Polymorphism) molecular marker influencing chicken first laying day age in laying hen breeding

Abstract

The invention provides application of an SNP (Single Nucleotide Polymorphism) molecular marker influencing the first laying day age of chickens in laying hen breeding, and belongs to the technical field of animal genetic breeding and biologication.The SNP molecular marker influencing the first laying day age of the chickens comprises AFEchr161 and / or AFEchr162; the Ensemb l number of the AFEchr161 is rs316781747, corresponds to the 2078538th site of a positive-sense strand of a chromosome 16 in a chicken reference genome bGa < l1 >. Mat.broi ler.GRCg7b sequence disclosed in NCBI (National Center of Biotechnology Information), and belongs to the first intron of a gene TRIM7.2, and the basic group at the site is G or C; the Ensemb l number of the AFEchr162 is rs15788024, corresponds to the 2121574 site of a positive-sense strand of a chromosome 16 in a chicken reference genome bGa < 1 >. Mat.broi ler.GRCg7b sequence disclosed in NCBI (National Center of Biotechnology Information), and belongs to the fourth intron of a gene TRIM39.2, and the basic group at the site is T or C. The invention also discloses a method for preparing the AFEchr162. The AFEchr161 and the AFEchr162 are both helpful for advancing the first laying day age of the laying hens from the aspect of heredity, and the AFEchr161 and the AFEchr162 are applied to genetic breeding of chickens, so that the first laying day age of the laying hens is shortened, and the requirements of an egg product market on green-shell laying hen varieties are met.

Description

Technical Field

[0001] The invention belongs to the field of animal genetic breeding and biotechnology, and particularly relates to the application of SNP molecular markers that affect the laying age of chickens in laying hen breeding. Background Art

[0002] The age at the start of laying is a commonly used indicator for breeding laying hens. It can be used to identify whether laying hens are sexually mature, measure the uniformity of the group, and predict egg-laying performance. Studies have shown that there is a clear lower limit for the age at the start of laying of poultry, and hens below the threshold cannot reach sexual maturity. The start of laying of chickens is a complex physiological development process, which is not only regulated by external environmental factors, such as the duration of light, but also affected by genetic factors. Generally speaking, only by genetically changing the frequency of related genes can lasting and cumulative progress be achieved. In recent years, the GWAS method has been extended to the analysis of the genetic structure of quantitative traits of laying hens, mainly used for the study of egg production, feed utilization efficiency and egg quality. It is rare to use the GWAS method to analyze the genetic structure of the age at the start of laying of laying hens. The age at the start of laying trait is regulated by micro-effect polygenes, and it is difficult for conventional breeding methods to obtain effective genetic progress. The only way is to clarify the genetic structure of the age at the start of laying, so as to achieve genetic influence on the age at the start of laying.

[0003] Dongxiang green-shell laying hens originated in the area near Dongxiang County, Jiangxi Province. They are a famous local egg-laying chicken breed in my country and a national geographical indication variety. Dongxiang green-shell laying hens are named after the production of green-shell eggs. After selection and breeding, Dongxiang green-shell laying hens are used to build the supporting systems of Suqin green-shell laying hens and Shendan No. 6 green-shell laying hens, occupying an important position in the laying hen market. Systematic research on the genetic structure of the laying age of Dongxiang green-shell laying hens is of great significance for the development and utilization of Dongxiang green-shell laying hens. The laying age is a late trait of the organism and can only be measured at the time of laying, which leads to an increase in the feeding cost of genetic breeding. Therefore, it is urgent to find suitable molecular markers to achieve early selection through genetic marker-assisted breeding or genomic selection, and quickly improve the laying age of laying hens.

[0004] Since Dongxiang green-shell laying hens have not undergone intensive breeding, their production performance is poor, especially the late start of laying and poor uniformity, which makes it difficult to meet the needs of modern laying hen production. In order to meet the demand for green-shell eggs in the egg market and to tap into the genetic resources of local chicken breeds in my country, it is urgent to find new molecular markers and enrich the genetic marker library related to the age of laying, so as to genetically shorten the age of laying hens. Summary of the invention

[0005] In order to genetically shorten the age at first egg of laying hens, the present invention provides the application of SNP molecular markers affecting the age at first egg of chickens in the breeding of laying hens. The SNP molecular markers affecting the age at first egg of chickens include AFE_chr16_1 and AFE_chr16_2. Both AFE_chr16_1 and AFE_chr16_2 contribute to genetically advancing the age at first egg of laying hens. Applying them to the genetic breeding of chickens is conducive to shortening the age at first egg of laying hens.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention provides the application of SNP molecular markers affecting the age at first egg of chickens in the breeding of laying hens. The SNP molecular markers affecting the age at first egg of chickens include AFE_chr16_1 and / or AFE_chr16_2;

[0008] The Ensembl ID of AFE_chr16_1 is rs316781747, corresponding to the 2,078,538th position on the plus strand of chromosome 16 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b published in NCBI, belonging to the first intron of the gene TRIM7.2, and the base here is G or C;

[0009] The Ensembl ID of AFE_chr16_2 is rs15788024, corresponding to the 2,121,574th position on the plus strand of chromosome 16 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b published in NCBI, belonging to the fourth intron of the gene TRIM39.2, and the base here is T or C.

[0010] Based on the same inventive concept, the present invention provides an early selection method for the age at first egg trait of chickens. The early selection method includes early selection of the age at first egg trait of chickens based on the genotypes of the SNP molecular markers AFE_chr16_1 and / or AFE_chr16_2;

[0011] The Ensembl ID of AFE_chr16_1 is rs316781747, corresponding to the 2,078,538th position on the plus strand of chromosome 16 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b published in NCBI, belonging to the first intron of the gene TRIM7.2, and the base here is G or C;

[0012] The Ensembl ID of AFE_chr16_2 is rs15788024, corresponding to the 2,121,574th position on the plus strand of chromosome 16 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the 4th intron of gene TRIM39.2, and the base here is T or C.

[0013] Further, the early selection method specifically includes:

[0014] Detect the genotypes of the SNP molecular markers AFE_chr16_1 and / or AFE_chr16_2 in the chicken to be tested;

[0015] Based on the genotypes of AFE_chr16_1 and / or AFE_chr16_2, conduct early selection on the age at first egg trait of the chicken to be tested;

[0016] Among them, the age at first egg of individuals with the CC genotype of AFE_chr16_1 is earlier than that of individuals with the GC and GG genotypes;

[0017] The age at first egg of individuals with the TT genotype of AFE_chr16_2 is earlier than that of individuals with the TC and CC genotypes.

[0018] Further, the detection of the genotypes of the SNP molecular markers AFE_chr16_1 and / or AFE_chr16_2 in the chicken to be tested specifically includes:

[0019] Detect the genotypes of the SNP molecular markers AFE_chr16_1 and / or AFE_chr16_2 in the chicken to be tested. Among them, the method for detecting the genotype of AFE_chr16_1 is as follows:

[0020] Using Pr_afe_16_1f and Pr_afe_16_1r as primers, perform PCR amplification on the genomic DNA of the chicken to be tested;

[0021] Sequence the PCR amplification product to obtain the genotype at the 2,078,538th position on the plus strand of chromosome 16 of the chicken to be tested;

[0022] The method for detecting the genotype of AFE_chr16_2 is as follows:

[0023] Using Pr_afe_16_2f and Pr_afe_16_2r as primers, perform PCR amplification on the genomic DNA of the chicken to be tested;

[0024] Sequence the PCR amplification product to obtain the genotype at the 2,121,574th position on the plus strand of chromosome 16 of the chicken to be tested;

[0025] Among them, the nucleotide sequence of Pr_afe_16_1f is shown in SEQ ID NO.1, and the nucleotide sequence of Pr_afe_16_1r is shown in SEQ ID NO.2; the nucleotide sequence of Pr_afe_16_2f is shown in SEQ ID NO.3, and the nucleotide sequence of Pr_afe_16_2r is shown in SEQ ID NO.4.

[0026] Furthermore, the breeds of the chickens to be tested include Dongxiang blue-shelled layer chickens and / or White Leghorn chickens.

[0027] Based on the same inventive concept, the present invention provides the application of a detection reagent for SNP molecular markers affecting the age at first egg in the genetic breeding of layer chickens. The SNP molecular markers affecting the age at first egg include AFE_chr16_1 and / or AFE_chr16_2;

[0028] The Ensembl ID of AFE_chr16_1 is rs316781747, corresponding to the 2,078,538th position on the plus strand of chromosome 16 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the first intron of the gene TRIM7.2, and the base here is G or C;

[0029] The Ensembl ID of AFE_chr16_2 is rs15788024, corresponding to the 2,121,574th position on the plus strand of chromosome 16 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the fourth intron of the gene TRIM39.2, and the base here is T or C.

[0030] Furthermore, the detection reagent for SNP molecular markers affecting the age at first egg includes primers for detecting AFE_chr16_1 and / or AFE_chr16_2. The primers for detecting AFE_chr16_1 include Pr_afe_16_1f and Pr_afe_16_1r, and the primers for detecting AFE_chr16_2 include Pr_afe_16_2f and Pr_afe_16_2r;

[0031] The nucleotide sequence of Pr_afe_16_1f is shown in SEQ ID NO.1, and the nucleotide sequence of Pr_afe_16_1r is shown in SEQ ID NO.2; the nucleotide sequence of Pr_afe_16_2f is shown in SEQ ID NO.3, and the nucleotide sequence of Pr_afe_16_2r is shown in SEQ ID NO.4.

[0032] Based on the same inventive concept, the present invention provides a kit for detecting SNP molecular markers affecting the age at first egg in chickens. The kit contains primers for detecting AFE_chr16_1 and / or AFE_chr16_2. The primers for detecting AFE_chr16_1 include Pr_afe_16_1f and Pr_afe_16_1r, and the primers for detecting AFE_chr16_2 include Pr_afe_16_2f and Pr_afe_16_2r;

[0033] The nucleotide sequence of Pr_afe_16_1f is shown in SEQ ID NO.1, and the nucleotide sequence of Pr_afe_16_1r is shown in SEQ ID NO.2; the nucleotide sequence of Pr_afe_16_2f is shown in SEQ ID NO.3, and the nucleotide sequence of Pr_afe_16_2r is shown in SEQ ID NO.4.

[0034] Based on the same inventive concept, the present invention provides the application of a kit for detecting SNP molecular markers affecting the age at first egg in chickens in chicken genetic breeding.

[0035] Based on the same inventive concept, the present invention provides the application of SNP molecular markers affecting the age at first egg in predicting the age at first egg in chickens. The SNP molecular markers affecting the age at first egg include AFE_chr16_1 and / or AFE_chr16_2;

[0036] The Ensembl number of AFE_chr16_1 is rs316781747, corresponding to the 2,078,538th position on the plus strand of chromosome 16 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the first intron of gene TRIM7.2, and the base here is G or C;

[0037] The Ensembl number of AFE_chr16_2 is rs15788024, corresponding to the 2,121,574th position on the plus strand of chromosome 16 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the fourth intron of gene TRIM39.2, and the base here is T or C.

[0038] One or more of the technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0039] Application of SNP molecular markers affecting the age at first egg in chickens in laying hen breeding. The SNP molecular markers affecting the age at first egg in chickens include AFE_chr16_1 and AFE_chr16_2. The dominant genotype population has an earlier age at first egg. Both AFE_chr16_1 and AFE_chr16_2 contribute to genetically advancing the age at first egg in laying hens. Applying them to chicken genetic breeding is beneficial to improving the age at first egg in laying hens. Brief Description of the Drawings

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for description in the embodiments. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0041] Figure 1 Manhattan plot of GWAS analysis of age at first egg in the resource population of Example 2 of the present invention;

[0042] Figure 2 QQ plot of GWAS analysis of age at first egg in the resource population of Example 2 of the present invention;

[0043] Figure 3 Box plot of age at first egg of individuals with different genotypes in Example 3 of the present invention;

[0044] Figure 4 Box plot of age at first egg of individuals with different genotypes in Example 4 of the present invention. Detailed Embodiments

[0045] The following will specifically describe the present invention in combination with specific embodiments and examples, and the advantages and various effects of the present invention will be presented more clearly therefrom. Those skilled in the art should understand that these specific embodiments and examples are used to illustrate the present invention, rather than to limit the present invention.

[0046] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as having the meaning as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as the general understanding of those skilled in the art to which the present invention belongs. In case of contradiction, this specification shall prevail.

[0047] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchases or can be prepared by existing methods.

[0048] The following will specifically describe the application of the SNP molecular markers affecting the age at first egg in chickens in laying hen breeding in combination with examples and experimental data.

[0049] Example 1

[0050] Construction of resource population

[0051] To analyze the genetic structure of egg-related traits, a laying hen resource population was constructed according to the F2 design. The local chicken breed Dongxiang blue-shelled layer and the selected breed White Leghorn were used as parents respectively. The F1 generation was obtained through reciprocal crosses, and then the F2 generation was bred with the F1 as parents. Pedigree information was recorded. The experimental chickens were individually tagged with wing numbers and raised in single cages in a fully enclosed chicken house. During the laying period, artificial supplementary lighting was provided for 16 hours, and the temperature was reduced by fans and wet curtains. Routine immunization was carried out according to the immunization program formulated by the Jiangsu Institute of Poultry Science. The feed was from COFCO Corporation. The feed components for laying hens included 16.5% crude protein and 11511 kJ / kg feed metabolic energy. During the laying period, the chickens had free access to food, were supplied with water through nipple drinkers, fed with a traveling feeder, and the chicken manure was removed by a chicken manure conveyor belt. The age at first egg of each experimental chicken was recorded.

[0052] The age-at-first-egg data was initially screened. After removing obviously incorrect and duplicate data, outliers were removed and the data was organized into an excel table form. The age-at-first-egg dataset of the F2 generation of the resource population remained 1512 records. One-way ANOVA was used to statistically analyze the effects of generation and breed on the experimental data, and the year and chicken house effects were determined as factors included in the fixed effects. The WOMBAT software was used to construct a genetic relationship matrix with pedigree data, and heritability and breeding values were calculated. The breeding values were used as pseudo-phenotype data for the next GWAS analysis and to analyze the genetic structure of the age at first egg.

[0053] Example 2

[0054] GWAS analysis of age at first egg

[0055] The experimental chickens were adult hens of the F2 generation of the laying hen resource population constructed in Example 1. About 0.5 ml of blood samples were collected from the wing veins of the experimental chickens and placed into BD anticoagulant tubes (BD Biosciences, Suzhou), and stored at -70 °C. Genomic DNA was extracted. After being detected by 0.8% agarose gel electrophoresis and ultraviolet spectrophotometry, the DNA samples were diluted to 50 ± 5 ng / μl after passing the tests, and used for genotyping with gene chips.

[0056] Using Affymetrix gene chips Genotyping was performed using the 600K Chicken Genotyping Array. Quality control of the data was carried out according to the chip manual, mainly including: performing quality control before genotyping using the APT software; performing quality control with PLINK, removing SNPs with a detection rate lower than 0.97 and SNPs deviating from the Hardy-Weinberg equilibrium; screening SNPs using metrics.R, SNP_filter.R, and SNP, CR, and FLD information analysis; and performing genotype imputation with BEAGLE. After quality control, 435,867 autosomal SNPs remained for subsequent analysis.

[0057] Before performing the genome-wide association study (GWAS), multi-dimensional principal component analysis was first carried out to eliminate false positives and population structure. The first five principal components were used as covariate parameters and added to the genetic model, and the chicken house effect was placed in the fixed effect of the model. The "simpleM" method in the R script was used to calculate the independent test estimates of each SNPs locus, and 59,308 independent markers were obtained. Using multiple corrections, the genome-wide significant threshold was obtained as 8.43×10 -7 , and the genome-recommended threshold was 1.69×10 -5 . The age at first egg was analyzed using the mixed linear model to obtain the P values of the significance tests for each SNPs marker. The matrix expression of the linear model is,

[0058] y = Wα + xβ + Gu + ε

[0059] where y represents the vector of sample phenotypic values; W represents the covariance matrix; α is the intercept vector; x is the genotype vector of the marker, and β is the effect value of the marker; G is the genetic relationship matrix constructed based on the chip, u is the random effect vector (here it is the breeding value); and ε is the residual.

[0060] After GWAS screening, AFE_chr16_1 associated with the age at first egg was obtained (Table 1). Genome-wide association analysis was performed on the age at first egg of 1,512 chickens, and the results are as Figure 1 、 Figure 2 shown. From Figure 1 (Manhattan plot), it can be seen that there are markers at the genome-wide significant level on chicken chromosome 16, and there are 2 SNPs around it exceeding the genome-recommended level, which can be used as evidence to support AFE_chr16_1. The QQ plot further verifies the reliability of the GWAS results. From Figure 2It can be seen from the (QQ plot) that the vast majority of SNPs that do not deviate from the diagonal line are affected by genetic drift, and the SNPs located at the tail of the QQ plot are under artificial selection. After calculation, the inflation coefficient is 1.016, indicating that there is no obvious population stratification in the age at first egg trait of the resource population. Using the pedigree genetic relationship matrix to analyze genetic parameters, the heritability of the age at first egg is 0.392 ± 0.046. Among them, the genetic marker AFE_chr16_1 can explain 1.14% of the phenotypic variance, and the genetic marker AFE_chr16_2 can explain 0.89% of the phenotypic variance.

[0061] Table 1 Genetic markers related to the age at first egg

[0062]

[0063] Wherein: the physical position of the marked chromosome refers to the chicken whole genome (bGalGal1.mat.broiler.GRCg7b).

[0064] Example 3

[0065] Detection and verification of the genetic marker AFE_chr16_1.

[0066] Using the above SNP genetic markers to conduct candidate gene association analysis on the Dongxiang Green-shelled Egg Chicken - White Leghorn chicken resource population. The specific operation steps are as follows:

[0067] 1) PCR primers: Download the DNA template sequence information from the NCBI website, and design PCR amplification primers with the primer premier 6.0 software. The primer information is shown in Table 2. The PCR primers are synthesized by Sangon Biotech (Shanghai) Co., Ltd.

[0068] Table 2 Amplification primers used to detect the genetic marker AFE_chr16_1 of the age at first egg in chickens

[0069]

[0070] 2) Genomic DNA extraction: Extract the genomic DNA of 1512 blood samples by the phenol-chloroform method. After being detected by an ultraviolet spectrophotometer and qualified by agarose gel electrophoresis, PCR amplification is carried out.

[0071] 3) PCR amplification process:

[0072] ① Reaction system: The 10 μl system includes 50 ng of the DNA template of the identification material, 10 ng of each of the forward and reverse primers, 5 μL of 2×power Taq MasterMix, and the remaining volume is made up with ultrapure water.

[0073] ②Reaction procedure: First, denature at 94°C for 30 s, anneal at 55.4°C for 30 s, extend at 72°C for 30 s, for a total of 5 cycles; then denature at 94°C for 30 s, anneal at 55.4°C for 30 s, extend at 72°C for 30 s, for a total of 30 cycles; extend at 72°C for 5 min, and store at 4°C.

[0074] 4) The amplified products were sent to a sequencing company for sequence polymorphism detection.

[0075] The sequences of the amplified fragments are as follows:

[0076] >AFE_chr16_1

[0077]

[0078] In the sequence, the sites marked [] are mutation sites, and the allelic variations are in parentheses. The primer sequences are shown in bold and underlined at the beginning and end of the sequence.

[0079] 5) Association analysis: All the tested individuals had genotypes and age at first egg laying, and then significance tests were performed. The results are as Figure 3 shown. The age at first egg laying of GG genotype individuals was 160.18 ± 10.64 days, that of GC genotype individuals was 154.67 ± 10.52 days, and that of CC genotype individuals was 152.71 ± 10.59 days. One-way ANOVA showed that there were significant differences in the age at first egg laying corresponding to the three genotypes (P<0.01). By using genotyping technology to increase the frequency of C allele, the age at first egg laying of laying hens can be shortened; by increasing the frequency of CC genotype, the uniformity of the age at first egg laying of laying hens can be further improved.

[0080] Example 4

[0081] Detection and verification of genetic marker AFE_chr16_2.

[0082] The above SNP genetic marker was used to perform candidate gene association analysis on Dongxiang blue-shelled layer - White Leghorn resource population. The specific operation steps are as follows:

[0083] 1) PCR primers: Download the DNA template sequence information from the NCBI website, and design PCR

[0084] amplification primers with primer premier 6.0 software. The primer information is shown in Table 3. The PCR primers were synthesized by Sangon Biotech (Shanghai) Co., Ltd.

[0085] Table 3 Amplification primers for detecting genetic marker AFE_chr16_2 of chicken age at first egg laying

[0086]

[0087]

[0088] 2) Genomic DNA extraction: Genomic DNA of 1512 blood samples was extracted by the phenol-chloroform method. After being qualified by ultraviolet spectrophotometer detection and agarose gel electrophoresis detection, PCR amplification was carried out.

[0089] 3) PCR amplification process:

[0090] ① Reaction system: The 10 μl system included 50 ng of DNA template of the identification material, 10 ng each of forward and reverse primers, 5 μL of 2×power Taq MasterMix, and the remaining volume was made up with ultrapure water.

[0091] ② Reaction program: First, denaturation at 94 °C for 30 s, annealing at 54.2 °C for 30 s, extension at 72 °C for 30 s, for a total of 5 cycles; then denaturation at 94 °C for 30 s, annealing at 54.2 °C for 30 s, extension at 72 °C for 30 s, for a total of 30 cycles; extension at 72 °C for 5 min, and stored at 4 °C.

[0092] 4) The amplified products were sent to a sequencing company for sequence polymorphism detection.

[0093] The sequences of the amplified fragments are shown as follows:

[0094] >AFE_chr16_2

[0095]

[0096] In the sequence, the sites marked [] are mutation sites, and the allelic variations are in parentheses. The primer sequences are shown in bold and underlined at the beginning and end of the sequence.

[0097] 5) Association analysis: All the test individuals had genotypes and age at first egg laying, and then significance tests were carried out. The results showed that the age at first egg laying of individuals with the CC genotype was 158.50 ± 10.97 days, that of individuals with the TC genotype was 154.64 ± 10.71 days, and that of individuals with the TT genotype was 152.93 ± 10.55 days. One-way ANOVA showed that there were significant differences in the age at first egg laying corresponding to the three genotypes. By using genotyping technology, increasing the frequency of the T allele can shorten the age at first egg laying of laying hens, and increasing the frequency of the TT genotype can improve the uniformity of the age at first egg laying.

[0098] Finally, it should also be noted that the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0099] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made by those skilled in the art once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0100] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. Application of SNP molecular markers affecting the age of chickens in laying hens breeding, characterized in that: The SNP molecular markers affecting the chicken's laying age include AFE_chr16_1 and / or AFE_chr16_2; The Ensembl number of the AFE_chr16_1 is rs316781747, corresponding to the 2078538th position of the positive strand of chromosome 16 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the first intron of gene TRIM7.2, where the base is G or C; The Ensembl number of the AFE_chr16_2 is rs15788024, corresponding to the 2121574th position of the positive strand of chromosome 16 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 4th intron of gene TRIM39.2, where the base is T or C.

2. A method for early selection of chicken laying age traits, characterized in that: The early selection method comprises performing early selection on the chicken laying age trait based on the genotype of the SNP molecular marker AFE_chr16_1 and / or AFE_chr16_2; The Ensembl number of the AFE_chr16_1 is rs316781747, corresponding to the 2078538th position of the positive strand of chromosome 16 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the first intron of gene TRIM7.2, where the base is G or C; The Ensembl number of the AFE_chr16_2 is rs15788024, corresponding to the 2121574th position of the positive strand of chromosome 16 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 4th intron of gene TRIM39.2, where the base is T or C.

3. The early selection method for chicken laying age traits according to claim 2, characterized in that: The early selection method specifically includes: Detecting the genotype of the chicken SNP molecular marker AFE_chr16_1 and / or AFE_chr16_2 to be tested; Performing early selection on the trait of the laying age of the chicken to be tested based on the genotype of the AFE_chr16_1 and / or the AFE_chr16_2; Among them, the first spawning age of individuals with CC genotype of AFE_chr16_1 is earlier than that of individuals with GC and GG genotypes; The age at which the individuals with the TT genotype of AFE_chr16_2 start spawning is earlier than that of the individuals with the TC and CC genotypes.

4. The early selection method for chicken laying age traits according to claim 3, characterized in that: The detecting the genotype of the chicken SNP molecular marker AFE_chr16_1 and / or AFE_chr16_2 to be tested specifically comprises: Detect the genotype of the chicken SNP molecular marker AFE_chr16_1 and / or AFE_chr16_2 to be tested, wherein the method for detecting the genotype of AFE_chr16_1 is as follows: The genomic DNA of the chicken to be tested was amplified by PCR using Pr_afe_16_1f and Pr_afe_16_1r as primers; The PCR amplification product was sequenced to obtain the genotype of position 2078538 of the positive strand of chromosome 16 of the tested chicken; The method for detecting the AFE_chr16_2 genotype is as follows: The genomic DNA of the tested chicken was amplified by PCR using Pr_afe_16_2f and Pr_afe_16_2r as primers; The PCR amplification product was sequenced to obtain the genotype of position 2121574 of the positive strand of chromosome 16 of the tested chicken; Among them, the nucleotide sequence of the Pr_afe_16_1f is shown as SEQ ID NO.1, and the nucleotide sequence of the Pr_afe_16_1r is shown as SEQ ID NO.2; the nucleotide sequence of the Pr_afe_16_2f is shown as SEQ ID NO.3, and the nucleotide sequence of the Pr_afe_16_2r is shown as SEQ ID NO.

4.

5. The early selection method for chicken laying age traits according to claim 3 or 4, characterized in that: The breeds of chickens to be tested include Dongxiang green-shell laying hens and / or white Leghorn chickens.

6. Application of a detection reagent for SNP molecular markers that affect the age of chickens in laying hens in genetic breeding, characterized in that: The SNP molecular markers affecting the chicken's laying age include AFE_chr16_1 and / or AFE_chr16_2; The Ensembl number of the AFE_chr16_1 is rs316781747, corresponding to the 2078538th position of the positive strand of chromosome 16 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the first intron of gene TRIM7.2, where the base is G or C; The Ensembl number of the AFE_chr16_2 is rs15788024, corresponding to the 2121574th position of the positive strand of chromosome 16 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 4th intron of gene TRIM39.2, where the base is T or C.

7. The use according to claim 6, characterized in that: The detection reagent of the SNP molecular marker affecting the chicken laying age includes primers for detecting AFE_chr16_1 and / or AFE_chr16_2, the primers for detecting AFE_chr16_1 include Pr_afe_16_1f and Pr_afe_16_1r, and the primers for detecting AFE_chr16_2 include Pr_afe_16_2f and Pr_afe_16_2r; The nucleotide sequence of the Pr_afe_16_1f is shown in SEQ ID NO.1, and the nucleotide sequence of the Pr_afe_16_1r is shown in SEQ ID NO.2; the nucleotide sequence of the Pr_afe_16_2f is shown in SEQ ID NO.3, and the nucleotide sequence of the Pr_afe_16_2r is shown in SEQ ID NO.

4.

8. A kit for detecting SNP molecular markers that affect the age of chicken laying, characterized in that: The kit comprises primers for detecting AFE_chr16_1 and / or AFE_chr16_2, wherein the primers for detecting AFE_chr16_1 include Pr_afe_16_1f and Pr_afe_16_1r, and the primers for detecting AFE_chr16_2 include Pr_afe_16_2f and Pr_afe_16_2r; The nucleotide sequence of the Pr_afe_16_1f is shown in SEQ ID NO.1, and the nucleotide sequence of the Pr_afe_16_1r is shown in SEQ ID NO.2; the nucleotide sequence of the Pr_afe_16_2f is shown in SEQ ID NO.3, and the nucleotide sequence of the Pr_afe_16_2r is shown in SEQ ID NO.

4.

9. Use of the kit as claimed in claim 8 in chicken genetic breeding.

10. Application of SNP molecular markers that affect the age of chickens to start laying in predicting the age of chickens to start laying, characterized in that: The SNP molecular markers affecting the chicken's laying age include AFE_chr16_1 and / or AFE_chr16_2; The Ensembl number of the AFE_chr16_1 is rs316781747, corresponding to the 2078538th position of the positive strand of chromosome 16 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the first intron of gene TRIM7.2, where the base is G or C; The Ensembl number of the AFE_chr16_2 is rs15788024, corresponding to the 2121574th position of the positive strand of chromosome 16 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 4th intron of gene TRIM39.2, where the base is T or C.

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