CN108728575B

CN108728575B - Major QTL site of brassica napus silique length character, SNP molecular marker and application

Info

Publication number: CN108728575B
Application number: CN201810641613.1A
Authority: CN
Inventors: 向阳; 杜才富; 唐敏强; 刘胜毅
Original assignee: GUIZHOU RAPE INSTITUTE
Current assignee: GUIZHOU RAPE INSTITUTE
Priority date: 2018-06-21
Filing date: 2018-06-21
Publication date: 2021-07-02
Anticipated expiration: 2038-06-21
Also published as: CN108728575A

Abstract

The invention provides a main effect QTL site of a brassica napus silique length character, which is positioned between the 27633011 th base and the 28268829 th base of an A09 chromosome of the brassica napus. Preferably, the contribution rate to the pod length trait of brassica napus is 53.49%. Closely linked to the first SNP molecular marker, which is located at base 27633011 and is either A or G, the mutation results in a polymorphism. Closely linked to a second SNP molecular marker located at base 28268829, being either A or C, the mutation resulting in a polymorphism. Closely linked to the peak SNP marker, which is located at base 28132534 and is either T or A, the mutation results in a polymorphism. Also provides related SNP molecular markers and application. The main effect QTL site of the brassica napus silique length character has high contribution rate to the brassica napus silique length character, plays a key role in regulating and controlling the brassica napus silique length, can be used for map-based cloning and molecular marker-assisted selection, and is suitable for large-scale popularization and application.

Description

Major QTL site of brassica napus silique length character, SNP molecular marker and application

Technical Field

The invention relates to the technical field of molecular biology and rape breeding, in particular to the technical field of brassica napus length traits, and specifically relates to a major QTL site of the brassica napus length trait, an SNP molecular marker and application thereof.

Background

Rape belonging to the genus Brassica (Brassica) of the family Brassicaceae (Cruciferae) is an important superior oil crop. Depending on the phytological and biological characteristics, oilseed rape can be divided into three main types: brassica napus (l.; 2n ═ 20, aa), Brassica juncea (coss.; 2n ═ 36, aabb), and Brassica napus (l.; 2n ═ 38, aacc). Cabbage type rape is one of the most important oil crops in the world, particularly in Asia, Europe and North America, and is also the first oil crop in China, and rapeseed oil accounts for more than 55% of edible vegetable oil produced in China. In recent years, with the continuous rise of labor price and production cost, the production and planting area of rape in China is reduced and the rape seed is in short supply, and correspondingly, the import quantity of the rape seed is continuously increased (http:// m. In the face of the severe situation of rape supply shortage in China, rape breeders in China put forward the fourth time of rape industry leap development targets marked by ' three high ' (high yield, high oil content and high efficiency) ' (Wanghongzhong (2010) history review and prospect of rape industry development in China. Chinese oil crop academic newspaper 32(2): 300-302). The cultivation of the new high-yield rape variety is one of the main tasks of rape breeding in the future, and important guarantee is certainly provided for the development of the rape industry and the oil safety in China.

The length of the silique is an important determinant factor of the rape seed yield and a breeding target character, and the definition of the genetic basis has important significance for improving the rape yield. The siliques play an important role in the development of rape yield, not only the sink organ where rape absorbs and accumulates the photosynthetic products produced by the leaves, but also the source organ that supplies nutrition for seed development (Bennett E J, et al. the role of the seed in seed development: Strategies for manipulating yield. New Phytologist,2011,190(4): 838-. In the late stage of seed development, the functional leaf area of rape is rapidly reduced, and photosynthesis of green siliques becomes the main source of nutrients required for seed development (KING S P, et al. carbohydrate content and enzyme metabolism in reforming canola plants. plant Physiology,1997,114(1): 153-. In addition, the cell wall of the silique also transmits signals to regulate the filling rate of rape seeds and the redistribution of nutrient substances (Ding Xiuqi. cabbage type spring rape silique and seed character research. Chinese oil, 1996,18(4): 28-30). In general, longer siliques produce more and larger seeds than shorter siliques: (

H, ORAL E.Relationships between yield and yield compositions on cured expressed cultures. Turkish Journal of agricultural and development, 1999,23(6):603-608), the yield potential of oilseed rape can be improved by cultivating the very-long-pod oilseed rape variety (national examination of the very-long-pod type high-yield double-low oilseed rape Huashuang No. 4. rural practical technology and information, 2006(4): 37). The length of siliques is very long in high-yield breeding of rapeExamined as yield-related traits (AYTAC Z, KINACI G. genetic variation and association students of the same quantitative manufacturers in the factory used (Brassica napus L.). African Journal of Biotechnology,2009,8(15): 3547-. The silique length of rape is a quantitative trait controlled by multiple genes, and the former carries out QTL positioning research on the silique length trait by adopting a parental mapping population to identify a plurality of QTLs for controlling the silique length trait variation, wherein more than 30 QTLs for controlling the silique length trait variation are detected on 15 chromosomes of Brassica napus at present, and the explained phenotype contribution rate is different from 5.5 to 53.4 percent (ZHANG L, et al. genetic and correlation analysis of silique-traits in Brassica napus L. by quantitative trait mapping. the Theoretical and related Genetics,2011,122(1): 21-31; ANG P, et al. identification of a major QTL for silique length and used weight in Brassica napus. No. 296. Brassica napus strain No. 125. related QTL analysis of silique length and related Brassica napus strain [ 2. Brassica napus strain and related QTL for quantitative trait, No. 285. 3, No. 125. related Brassica napus strain and related Brassica napus L. No. 2. No. 5, No. 3, 2, No. 5, 3, No. 3, 2, No. 5, 3, 2, 3, 2, 3]Wuhan-Huazhong university of agriculture 2014).

Therefore, it is desirable to provide a major QTL locus for the silique length trait of brassica napus, which has a high contribution rate to the silique length trait of brassica napus, plays a key role in the control of the silique length of brassica napus, and can be used for site-directed cloning and molecular marker-assisted selection.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a main effect QTL site of the brassica napus silique length character, which has high contribution rate to the brassica napus silique length character, plays a key role in regulating and controlling the brassica napus silique length, can be used for site-directed cloning and molecular marker assisted selection, and is suitable for large-scale popularization and application.

The invention also aims to provide the SNP molecular marker of the major QTL site of the silique length character of the brassica napus, which can detect the length of the silique length of the brassica napus, can predict the length of the silique length of the brassica napus, can effectively select the length of the silique length of the brassica napus, can be used for molecular marker-assisted breeding of the brassica napus with long silique length, accelerates the high-yield breeding process of the brassica napus, and is suitable for large-scale popularization and application.

The invention also aims to provide the SNP molecular marker of the major QTL site of the silique length character of the brassica napus, which has the advantages of ingenious design, simple and quick detection, low cost, no environmental influence and suitability for large-scale popularization and application.

Another objective of the present invention is to provide an application of the SNP molecular marker of the major QTL site of the silique length trait of brassica napus, which can be used to detect the length of the silique length of brassica napus, predict the length of the silique length of brassica napus, effectively select the length of the silique length of brassica napus, assist breeding with the molecular marker of the brassica napus having a long silique length, accelerate the high yield breeding process of brassica napus, and is suitable for large-scale popularization and application.

The invention also aims to provide application of the SNP molecular marker of the main effect QTL site of the silique length character of the cabbage type rape, which has the advantages of ingenious design, simple and quick detection, low cost, no environmental influence and suitability for large-scale popularization and application.

To achieve the above object, in a first aspect of the present invention, there is provided a major QTL locus for the silique length trait of brassica napus, characterized in that the major QTL locus for the silique length trait of brassica napus is located between the 27633011 st base and the 28268829 th base of the chromosome a09 of brassica napus.

Preferably, the contribution rate of the main effect QTL site of the brassica napus silique length character to the brassica napus silique length character is 53.49%.

Preferably, the main QTL site of the brassica napus silique length trait is closely linked with a first SNP molecular marker, the first SNP molecular marker is located at 27633011 th base, the 27633011 th base is A or G, and the mutation causes polymorphism.

Preferably, the main QTL site of the brassica napus silique length trait is closely linked with a second SNP molecular marker, the second SNP molecular marker is located at 28268829 th base, the 28268829 th base is A or C, and the mutation causes polymorphism.

Preferably, the main QTL site of the brassica napus silique length trait is closely linked with a peak SNP molecular marker, wherein the peak SNP molecular marker is located at 28132534 th base, the 28132534 th base is T or A, and the mutation causes polymorphism.

In a second aspect of the invention, the SNP molecular marker of the major QTL site of the silique length trait of the cabbage type rape is provided, and is characterized in that the SNP molecular marker is located at the 27633011 th base of the A09 chromosome of the cabbage type rape, the 27633011 th base is A or G, and the mutation causes polymorphism.

In a third aspect of the present invention, there is provided the use of the above-mentioned SNP molecular marker for a major QTL locus for the silique length trait of brassica napus for detecting the length of silique length of brassica napus, predicting the length of silique length of brassica napus, selecting the length of silique length of brassica napus, or molecular marker-assisted breeding of brassica napus with long silique length.

In the fourth aspect of the invention, the SNP molecular marker of the major QTL site of the silique length trait of the cabbage type rape is provided, and is characterized in that the SNP molecular marker is positioned at the 28268829 th base of the A09 chromosome of the cabbage type rape, the 28268829 th base is A or C, and the mutation causes polymorphism.

In a fifth aspect of the present invention, the application of the above-mentioned SNP molecular marker for the major QTL locus of the brassica napus length trait in detecting the length of the brassica napus, predicting the length of the brassica napus, selecting the length of the brassica napus, or in molecular marker-assisted breeding of brassica napus with long silique length is provided.

In the sixth aspect of the invention, the peak SNP molecular marker of the major QTL site of the silique length trait of the cabbage type rape is provided, and is characterized in that the peak SNP molecular marker is located at the 28132534 th base of the A09 chromosome of the cabbage type rape, the 28132534 th base is T or A, and the mutation causes polymorphism.

In a seventh aspect of the present invention, there is provided the use of the above-mentioned peak SNP molecular marker for the major QTL locus for the brassica napus length trait for detecting the length of the brassica napus, predicting the length of the brassica napus, selecting the length of the brassica napus, or molecular marker-assisted breeding of brassica napus with long silique length.

The invention has the following beneficial effects:

1. the main effect QTL site of the silique length character of the brassica napus is positioned between the 27633011 th base and the 28268829 th base of the chromosome A09 of the brassica napus, has high contribution rate to the silique length character of the brassica napus, plays a key role in regulating and controlling the silique length of the brassica napus, can be used for map location cloning and molecular marker assisted selection, and is suitable for large-scale popularization and application.

2. The SNP molecular marker of the main effect QTL site of the silique length character of the cabbage type rape comprises an SNP molecular marker of a 27633011 th base of an A09 chromosome of the cabbage type rape, an SNP molecular marker of a 28268829 th base of an A09 chromosome of the cabbage type rape and a peak SNP molecular marker of a 28132534 th base of an A09 chromosome of the cabbage type rape, can detect the length of the silique length of the cabbage type rape, can predict the length of the silique length of the cabbage type rape, can effectively select the length of the silique length of the cabbage type rape, can also be used for molecular marker assisted breeding of the brassica type rape with long silique length, accelerates the high-yield breeding process of the cabbage type rape, and is suitable for large-scale popularization and application.

3. The SNP molecular marker of the main effect QTL site of the silique length character of the cabbage type rape comprises an SNP molecular marker of a 27633011 th base of an A09 chromosome of the cabbage type rape, an SNP molecular marker of a 28268829 th base of an A09 chromosome of the cabbage type rape and a peak SNP molecular marker of a 28132534 th base of an A09 chromosome of the cabbage type rape.

4. The application of the SNP molecular marker of the main effect QTL site of the silique length character of the cabbage type rape comprises the application of the SNP molecular marker of the 27633011 th base of the A09 chromosome of the cabbage type rape, the application of the SNP molecular marker of the 28268829 th base of the A09 chromosome of the cabbage type rape and the application of the peak value SNP molecular marker of the 28132534 th base of the A09 chromosome of the cabbage type rape.

5. The application of the SNP molecular marker of the main effect QTL site of the silique length character of the cabbage type rape comprises the application of the SNP molecular marker of the 27633011 th base of the A09 chromosome of the cabbage type rape, the application of the SNP molecular marker of the 28268829 th base of the A09 chromosome of the cabbage type rape and the application of the peak SNP molecular marker of the 28132534 th base of the A09 chromosome of the cabbage type rape.

These and other objects, features and advantages of the present invention will become more fully apparent from the following detailed description, the accompanying drawings and the claims, and may be realized by means of the instrumentalities, products and combinations particularly pointed out in the appended claims.

Drawings

FIG. 1 is a schematic diagram of the distribution results of the pod length trait of Brassica napus according to the present invention.

FIG. 2 is a schematic diagram of allelic analysis using peak SNP molecular markers of major QTL sites for the silique length trait of Brassica napus in accordance with the present invention.

Detailed Description

Through intensive research, the inventor firstly discloses a main effect QTL site of the silique length character of the cabbage type rape and an SNP molecular marker thereof, and can effectively and efficiently improve the yield of the cabbage type rape by utilizing the main effect QTL site.

The main effect QTL locus of the brassica napus silique length character is positioned between the 27633011 th base and the 28268829 th base of the A09 chromosome of the brassica napus.

Also provides an SNP molecular marker of a main effect QTL site of the brassica napus silique length character, which is located at the 27633011 th base of the A09 chromosome of the brassica napus, wherein the 27633011 th base is A or G, and the mutation causes polymorphism. Namely the first SNP molecular marker.

Also provides the application of the SNP molecular marker of the main effect QTL site of the brassica napus silique length character in detecting the length of the brassica napus silique, predicting the length of the brassica napus silique, selecting the length of the brassica napus silique or carrying out molecular marker assisted breeding on the brassica napus silique with long silique length.

Also provides an SNP molecular marker of a main effect QTL site of the brassica napus silique length character, which is located at the 28268829 th base of the A09 chromosome of the brassica napus, wherein the 28268829 th base is A or C, and the mutation causes polymorphism. Namely the second SNP molecular marker.

Also provides a peak SNP molecular marker of a main effect QTL site of the brassica napus silique length character, which is located at the 28132534 th base of the A09 chromosome of the brassica napus, wherein the 28132534 th base is T or A, and the mutation causes polymorphism.

Also provides the application of the peak SNP molecular marker of the main effect QTL site of the brassica napus length character in detecting the length of the brassica napus, predicting the length of the brassica napus, selecting the length of the brassica napus or carrying out molecular marker assisted breeding on the brassica napus with long pod length.

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The experimental procedures, for which specific conditions are not noted in the following examples, are generally performed according to conventional conditions such as those described in J. SammBruk et al, molecular cloning protocols, third edition, scientific Press, 2002, or according to the manufacturer's recommendations.

Example 1 determination of phenotype of the Brassica napus silique Length trait

1. Determination of silique length phenotype of related populations

(1) Carrying out field seed test analysis on the agronomic and quality traits of 627 parts of core germplasm materials (from a seed bank of the oil-vegetable research institute in Guizhou province), and selecting 300 high-generation brassica napus strains from all over the world to form a natural population, wherein the natural population comprises 98 parts of resources, 110 parts of breeding materials and 92 parts of varieties or parents; the method is divided into regions, wherein 246 parts belong to domestic and 54 parts belong to foreign sources. 3-year 2-point phenotype identification is completed on rape bases in Weiyuan village and Changxing town of Kaiyang county in Guiyang city.

(2) Direct seeding and final singling are adopted, the row spacing is 40cm, the planting spacing is 25cm, and 4 rows are arranged in each cell. And (4) planting protective rows around the test material field.

(3) Length of silique: after the plants are normally mature, 3, 4 and 3 complete siliques are taken from the upper part, the middle part and the lower part of the main inflorescence of each plant, and the length of the body of each silique (excluding a fruit stem and a fruit beak) is measured, wherein the unit is centimeter and the accuracy is 0.1 cm. The tabular values for all environments were averaged for 300 parts of material and the results are summarized as follows:

TABLE 1300 materials average of all ambient silique length phenotype values

The silique length distribution result of the associated population shows that the silique length character expression distribution is in continuous distribution and normal distribution, and the silique length character is proved to belong to quantitative characters and have main effect gene loci, which are shown in figure 1. 2. Acquisition of related population high quality SNP data set

The method comprises the following steps of (1) extracting total DNA of leaves by adopting a CTAB method, and extracting the total DNA of the leaves of each material of a related population, wherein the specific method comprises the following steps:

rinsing the young and tender leaves in 10% ethanol; then shearing 0.1-0.2g of blades, putting the blades into a bowl mill, quickly milling the blades into powder by using liquid nitrogen, and putting the powder into a 2mL centrifuge tube; adding 700 mu L of preheated DNA extracting solution; mixing, placing in 65 deg.C water bath for 1h, and mixing for 1 time every 10-15 min; adding 700 μ L of mixed solution (phenol: chloroform: isoamyl alcohol 25: 24: 1), and mixing by gentle inversion for 10 min; centrifuging at room temperature at 10000 Xg for 15 min; sucking the supernatant into a new 2mL centrifuge tube; adding equal volume of mixed solution (chloroform: isoamyl alcohol is 24: 1), mixing, standing for 5min, centrifuging for 15min at 10000 Xg, and sucking supernatant into a new centrifuge tube with a gun; adding 2 times volume of anhydrous ethanol, mixing, standing at-20 deg.C for 1 hr at 10000 Xg, centrifuging for 10min, and removing supernatant; adding 500 μ L of precooled 75% ethanol, washing the precipitate, and removing the supernatant; washing and precipitating for 2 times continuously, and then airing; adding 100 μ L RNase A solution containing 2% RNase A, standing at 37 deg.C for 1h, and standing at 4 deg.C overnight; re-extracting DNA solution with equal volume of mixed solution (chloroform: isoamyl alcohol: 24: 1), reversing, mixing, standing for 10min, 10000 Xg, centrifuging for 15 or 20min, removing RNase A, sucking supernatant (about 60 μ L), and centrifuging again for 1 min; detecting the concentration, quality and integrity of the DNA by agarose gel electrophoresis (0.8%) and an ultraviolet spectrophotometer; the ratio of the absorbance 260/280 was determined to be between 1.8 and 2.0 for all DNA samples. The DNA samples were then transported on dry ice to sequencing Inc. (Huada science and technology, Inc.), each material having a sequencing depth of about 9X.

After obtaining high quality DNA as described above, the sequencing company (Huada Gene science and technology Co., Ltd.) performed 9 Xcoverage depth sequencing and returned data, and the sequencing quality was evaluated by using FastQC software, and then adapter and low quality reads were performed on the sequencing sequence. Obtaining clear data of double-end sequencing of each material, then using bwa software to carry out mapping and GATK software to carry out mutation detection, and after obtaining a total SNP data set of an associated group, carrying out SNP data set quality filtering according to the minimum allele frequency of more than or equal to 0.05, the deletion rate of less than or equal to 0.1 and the heterozygosity rate of less than or equal to 0.15, and finally obtaining a high-quality group SNP data set for subsequent analysis. 3. Whole genome association analysis

Using plink software to perform format conversion on a VCF file of the high-quality SNP data set generated in the last step, then using EMMAX software to perform whole-gene association analysis on the obtained silique length phenotype and the SNP data set to obtain a P value of each site of the silique length character, and when the P value is less than 5 multiplied by 10^-7The SNP is obvious SNP, the SNP with the minimum P value is peak SNP, and the peak SNP is different alleles in a populationGrouping the materials according to types, and carrying out variance analysis, wherein the percentage of the ratio of the variance between groups to the total variance is the contribution rate of the peak SNP.

Through analysis, the interval of the major QTL locus of the silique length trait of the cabbage type rape is limited between the 27633011 th base and the 28268829 th base of the A09 chromosome of the cabbage type rape, the corresponding SNPs are chrA09_27633011(A/G), chrA09_28268829(A/C), and the peak SNP is: and the contribution rate of the QTL to the silique length character of the brassica napus is 53.49% (the materials are grouped according to different allele types of peak SNP, the one-way anova is carried out, and the percentage of the group variance divided by the total variance is the contribution rate).

The peak SNPs for the silique length trait were: chrA09_28132534(A/T), grouped for pod length phenotype: when the SNP at position chrA09_28132534 is AA, the average silique length of the material is 7.26 cm; AT, the average silique length of the material was 6.29 cm; at TT, the average silique length of the material was 5.51cm, as shown in FIG. 2.

One of the border SNPs for the silique length trait is: chrA09_27633011(A/G), corresponding to the silique length phenotype grouping: when the SNP at the position chrA09_27633011 is GG, the average silique length of the material is 6.58 cm; at GA, the average silique length of the material was 6.26 cm; in AA, the average silique length of the material was 5.79cm, and the contribution of the border SNP was 11.39%.

Another border SNP for the silique length trait is: chrA09_28268829(A/C), grouped for pod length phenotype: when the SNP at position chrA09_28268829 is CC, the average silique length of the material is 5.87 cm; at CA, the average silique length of the material is 6.49 cm; in AA, the average silique length of the material was 7.62cm, and the contribution of this border SNP was 18.41%.

The whole genome sequence of Brassica napus has been published, see http:// www.genoscope.cns.fr/brassicianapus/. The sequences (801 bp in total) of 400bp in front and back of the sequence containing chrA 09-27633011 (A/G) are shown as SEQ ID NO:1, the sequences (801 bp in total) of 400bp in front and back of the sequence containing chrA 09-28268829 (A/C) are shown as SEQ ID NO:2, and the sequences (801 bp in total) of 400bp in front and back of the sequence containing chrA 09-28132534 (A/T) are shown as SEQ ID NO: 3. The technicians in the field can adopt a conventional method to design a specific primer for detecting the SNP locus according to the sequence so as to detect the genotype of the SNP locus, thereby being capable of detecting the length of the pod length of the cabbage type rape, predicting the length of the pod length of the cabbage type rape, effectively selecting the length of the pod length of the cabbage type rape, and being also capable of being used for molecular marker assisted breeding of the pod length cabbage type rape and accelerating the high-yield breeding process of the cabbage type rape.

Therefore, the method detects a main effect QTL site of the brassica napus silique length character on the chromosome A09 of the brassica napus by phenotype analysis and whole genome re-sequencing of the silique length character and then whole genome association analysis, and the contribution rate of the main effect QTL site to the brassica napus silique length is 53.49%. The main effect QTL locus of the silique length character of the cabbage type rape is positioned between the 27633011 th base and the 28268829 th base of an A09 chromosome of the cabbage type rape, the obvious SNP of the boundary is chrA 09-27633011 (A/G), chrA 09-28268829 (A/C), the peak SNP is chrA 09-28132534 (A/T), according to the SNP molecular marker tightly linked with the main effect QTL locus, the method can be used for detecting the length of the silique length of the cabbage type rape, predicting the length of the silique length of the cabbage type rape, effectively selecting the length of the silique length of the cabbage type rape, and also can be used for the molecular marker assisted breeding of the silique length cabbage type rape, and accelerating the high-yield process of the cabbage type rape.

The SNP molecular marker disclosed by the invention is used for carrying out molecular marker-assisted selection, the identification method is simple, the selection efficiency is high, and the silique length of the cabbage type rape can be predicted. The selection target is clear and is not influenced by the environment. The individual cabbage type rape with long silique length can be identified in the early growth stage of cabbage type rape, and other individual plants are eliminated.

In conclusion, the major QTL site for the silique length trait of the brassica napus has high contribution rate to the silique length trait of the brassica napus, plays a key role in regulating and controlling the silique length of the brassica napus, can be used for site cloning and molecular marker assisted selection, and is suitable for large-scale popularization and application.

It will thus be seen that the objects of the invention have been fully and effectively accomplished. The functional and structural principles of the present invention have been shown and described in the embodiments, and the embodiments may be modified without departing from the principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the claims.

Claims

1. An SNP molecular marker of a main effect QTL site of the silique length character of the cabbage type rape, which is characterized in that the SNP molecular marker is positioned at the 401 st base of a nucleotide sequence shown as SEQ ID NO. 1, the 401 st base is A or G, and the mutation causes polymorphism.

2. Use of a reagent for detecting SNP molecular markers of major QTL sites for the silique length trait of Brassica napus according to claim 1 for detecting the length of silique in Brassica napus, predicting the length of silique in Brassica napus, selecting the length of silique in Brassica napus, or molecular marker assisted breeding of Brassica napus with long silique length.

3. An SNP molecular marker of a main effect QTL site of the silique length character of the cabbage type rape, which is characterized in that the SNP molecular marker is positioned at the 401 st base of a nucleotide sequence shown as SEQ ID NO. 2, the 401 st base is A or C, and the mutation causes polymorphism.

4. Use of a reagent for detecting SNP molecular markers of major QTL sites for the silique length trait of Brassica napus according to claim 3 for detecting the length of silique in Brassica napus, predicting the length of silique in Brassica napus, selecting the length of silique in Brassica napus, or molecular marker assisted breeding of Brassica napus with long silique length.

5. A peak SNP molecular marker of a main effect QTL site of a brassica napus silique length character is characterized in that the peak SNP molecular marker is positioned at the 401 st base of a nucleotide sequence shown as SEQ ID NO. 3, the 401 st base is T or A, and the mutation causes polymorphism.

6. Use of a reagent for detecting a peak SNP molecular marker of a major QTL site for a brassica napus length trait according to claim 5 for detecting the length of a brassica napus pod, predicting the length of a brassica napus pod, selecting the length of a brassica napus pod, or molecular marker assisted breeding of brassica napus with a long pod length.