WO2013060126A1 - Mlpa长探针制备方法、转基因玉米mlpa长探针及检测方法 - Google Patents
Mlpa长探针制备方法、转基因玉米mlpa长探针及检测方法 Download PDFInfo
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- C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
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- C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
- C12Q1/68—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving nucleic acids
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- C12Q1/6888—Nucleic acid products used in the analysis of nucleic acids, e.g. primers or probes for detection or identification of organisms
- C12Q1/6895—Nucleic acid products used in the analysis of nucleic acids, e.g. primers or probes for detection or identification of organisms for plants, fungi or algae
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- C12Q2600/00—Oligonucleotides characterized by their use
- C12Q2600/16—Primer sets for multiplex assays
Definitions
- the present invention relates to the field of nucleic acid molecule detection, and more particularly to a method for preparing a long probe for MLPA detection technology, a long probe for GMPA detection of transgenic corn prepared by the method, and MLPA detection for transgenic corn. Background technique
- genetic testing is based on PCR technology, which is fast, sensitive, accurate and reliable.
- the PCR method analyzes only one gene in a single tube and is inefficient.
- it is necessary to screen one by one for many genetically modified varieties and strains, and the workload is too large and the cost is high. Therefore, genetic testing urgently requires a high-throughput assay.
- Common high-throughput gene detection technologies include gene chip, multi-channel capillary electrophoresis, and DHPLC separation technology.
- these methods generally only perform "single-to-many” testing (single-sample-to-multi-project), and the "many-to-many” approach (multi-sample to multi-project) has limited capabilities, and its limited high-throughput performance depends on The number of genes to be examined contained in the sample on the machine.
- multiplex PCR is used, but the mutual interference between the primers and the primer multimer makes it difficult to detect more than 10 genes in the technique.
- the Multiplex Ligation dependent Primers Amplification MLPA was initiated in 2002 by Dr. Schouten JP of the Netherlands and was originally used for medical testing purposes.
- the principle is to design probe pairs of different lengths for different gene loci of interest, and the probes are gene-specific to one end of the two sequences, and only one gap is left after renaturation with the respective target gene regions. All of the probe pairs are ligated with the same base sequence (both universal sequence) for the PCR, so that when the probe pair is renatured with the target region and ligated by the ligase, it becomes itself PCR template DNA, amplified by a pair of common primers, and signal amplified. Since the lengths of probe pairs designed for different loci of interest are different, the size of the isolated PCR product (without sequencing) can be used to know whether There is a target gene present, and a relative quantitative analysis can be performed.
- MLPA technology includes probe design, hybridization of probe and target sequence DNA, followed by ligation, PCR amplification, product separation by agarose gel electrophoresis or capillary electrophoresis, and data collection. It is economical (no expensive equipment), high specificity (probe renaturation and ligase recognition) and high throughput (single tube can measure up to 40 genes). In addition, the method detects The targeted target region can be as short as 40-50 bp, which is especially suitable for the detection of highly degraded DNA samples. To date, MLPA technology has been applied in many fields, such as single nucleotide polymorphism and gene mutation detection, gene fragment deletion and duplication, chromosome number abnormality, gene thiolation detection and mRNA analysis.
- the above MLPA technology principle shows that the polygenic loci differ from each other by the length of the final PCR amplified fragment.
- the gap between the amplified fragments must be opened. Therefore, the size of the probe must be pulled apart during the design and preparation of the single-stranded probe.
- the length of the single-stranded probe also increases, while the preparation of the single-stranded probe is It is difficult.
- the single-stranded probe is prepared by chemical synthesis. However, when the single-stranded probe exceeds 100 bp, the chemical synthesis method is not suitable, because the probability of occurrence of synthetic errors is greatly increased, and the yield of synthesis is greatly reduced.
- the Dutch company MRC-Holland which invented MLPA, developed a single-strand probe preparation method based on a set of M13 vectors, the principle of which is to make irrelevant or unrelated templates of different sizes of each M13 vector. (Unrelated Template, UT) Introduces single-stranded probes to obtain single-stranded probes of different lengths.
- the single-strand probe biological method is very cumbersome, and requires not only gene cloning, virus transfection, plasmid extraction, but also an expensive M13 vector.
- the M13 virus is highly susceptible to contamination.
- the Dutch company MRC-Holland is no longer selling M13 carriers. Therefore, the preparation of single-chain long probes is urgently needed to be overcome. Summary of the invention
- the object of the present invention is to provide a single, non-polluting and highly efficient MLPA long probe preparation method for the cumbersome problem of the above MLPA long probe biological preparation method.
- Another object of the present invention is to provide a long probe, short probe and MLPA detection method for transgenic maize for MLPA detection of transgenic maize.
- the invention discloses a preparation method of a MLPA long probe, which comprises asymmetric PCR amplification using a primer pair template, and then treating the asymmetric PCR amplification product with a restriction enzyme, and the gel electrophoresis is subjected to enzymatic digestion.
- Asymmetric PCR amplification product the single-stranded DNA in the asymmetric PCR amplification product is recovered by gelatinization to obtain a MLPA long probe;
- the template is a sequence unrelated to the detection target sequence, and the asymmetric PCR amplification product is Included in the sequence a restriction site, the restriction endonuclease corresponding to the multiple cloning site; a primer of the primer pair from 5, end to 3, the end includes a segment matching the detection target sequence and the template The matched segment; the other primer of the primer pair, from 5, end to 3, in turn comprises a segment that matches the MLPA universal primer and a segment that matches the template.
- the MLPA in the present invention refers to a multiplex ligation-dependent probe amplification (MLPA), and the MLPA long probe refers to a probe prepared by the M13 phage derivatization method in the prior art.
- the template is a sequence that needs to be inserted or partially inserted into a long probe by asymmetric PCR, and therefore, as long as it has no homology with the target sequence to be detected, or has a low homology relationship, or a large sequence difference, And it is not necessary to use a long probe for the sequence that adversely affects the MLPA detection.
- the detection target sequence refers to the nucleotide sequence of the MLPA-detected subject, that is, the nucleotide sequence of the sample to be detected.
- the recovery refers to a process of isolating single-stranded DNA from asymmetric PCR.
- the MLPA universal primer refers to a sequence which is independent of the detection target sequence at the 5th end of the MLPA long probe and the short probe, and is used for PCR amplification of the linked probe after the MLPA hybridization is successful.
- the multiple cloning site is a DNA sequence having at least one restriction endonuclease site. The restriction endonuclease treatment is carried out using an endonuclease corresponding to the cleavage site contained in the multiple cloning site.
- a primer comprising a segment matching the detection target sequence and a segment matching the template in the primer pair from the 5th end to the 3rd end is asymmetric PCR.
- the other primer is a defined primer; the 5th end of the non-limiting primer has a phosphorylation modification.
- the non-limiting primer refers to the primer which is used in a relatively large amount in the asymmetric PCR, and the defined primer refers to the primer which is used in a relatively small amount.
- the resulting single-stranded DNA is guided by undefined primers.
- the template is a PUC18 plasmid
- the restriction enzyme includes at least one of HindIII and EcoR1.
- the non-limiting primer is an upstream primer in asymmetric PCR, and the defined primer is a downstream primer; the upstream primer is located on the left side of the multiple cloning site of the PUC18 plasmid, and contains Seq ID No. The sequence shown in 2;
- the upstream primer has the same binding region to the PUC18 plasmid and is located on the left side of the multiple cloning site of the plasmid.
- the downstream primer is placed downstream of the multiple cloning site of the PUC 18 plasmid according to the length of the sequence in which the long probe is inserted. Count.
- the invention also discloses a MLPA long probe of transgenic corn, wherein the MLPA long probe has a phosphorylation modification at the 5th end, and includes a T2, UT, P2 segment from 5, end to 3, and end.
- T2 is a detection region that matches the detection target sequence
- UT is an insertion sequence unrelated to the detection target sequence
- P2 is a binding region of the MLPA universal primer pair; and P2 contains the sequence shown by Seq ID No.
- the T2 contains the sequence shown by Seq ID No. 3, and the UT contains the sequence shown by Seq ID No. 12.
- the T2 contains the sequence shown by Seq ID No. 5, and the UT contains the sequence shown by Seq ID No. 13;
- Seq ID No. 3 5 '-CTTTGCCATTGCCCAGCTATCTGTCACTTTATTGT-3 '
- Seq ID No. 5 5' -AGTCGGGTTTGGATGGTCAACTCCGGCATACTG-3 '
- Seq ID No.11 5 ' -TCTAGATTGGATCTTGCTGGCGC-3 '
- the 5' end of the MLPA detection medium long probe is the key to ensure its detection specificity. Therefore, those skilled in the art can understand that based on the above published long probe sequence, in the T2
- the basic function of the long probe of the present invention can still be achieved by replacing, adding or deleting a few bases at the 3' end or at the ends or in the middle of the UT or P2.
- the method for preparing the MLPA long probe comprises: using a primer pair to perform asymmetric PCR amplification using a PUC18 plasmid as a template, and recovering single-stranded DNA in the amplified product, that is, a MLPA long probe;
- the primer pair is composed of a non-limiting primer and a defined primer, and the 5th end of the non-limiting primer is phosphorylated;
- the non-limiting primer includes a T2 and UT1 segment in sequence from 5, end to 3, T2 is a detection region matching the detection target sequence, and UT 1 is a region matching the asymmetric PCR template; 5, end to 3, the end includes ⁇ 2, and UT2 segments in sequence; ⁇ 2, is the region matched by the MLPA universal primer, UT2 is the region matching the asymmetric PCR template; the ⁇ 2, containing Seq ID No. l
- the UT1 contains the sequence shown by Seq ID No. 2
- the T2 contains the sequence shown
- T2 contains the sequence shown by Seq ID No. 5
- UT2 contains the sequence shown by Seq ID No. 6.
- the undefined primer contains a sequence represented by Seq ID No. 7, and the defined primer contains a sequence represented by Seq ID No. 8.
- the undefined primer contains the sequence shown by Seq ID No. 9
- the defined primer contains the sequence shown by Seq ID No. 10.
- Seq ID No. l 5 '-GCGCCAGCAAGATCCAATCTAGA-3 '
- Seq ID No. 4 5'-CAGGCATGCAAGCTTGGCACTGG-3'
- Seq ID No.6 5 '-CAATTTCACACAGGAAACAGCTATGA-3 '
- asymmetric PCR amplification of MLPA long probes is by way of undefined primers consisting of T2 and UT1 segments, and defined primers consisting of P2' and UT2 segments, in asymmetric PCR, primers
- the UT1 or UT2 is matched with the template of the asymmetric PCR, that is, the PUC18 plasmid, and then amplified.
- the amplified product will have two primers at each of the 5 ends, T2 and P2. Since the long probe 5 and the end need to be phosphorylated, the asymmetric PCR amplification of the undefined primer of the single-stranded DNA is phosphorylated.
- the above-mentioned primer pair sequence of the present invention can basically realize asymmetric PCR using PUC18 plasmid as a template, between UT1 or UT2 or P2, both ends or in the middle, T2 intermediate, T2 and UT1. , or the replacement, addition or reduction of several bases between P2 and UT2 can also achieve the basic functions required by the present invention.
- the MLPA long probe for detecting transgenic corn has a sequence represented by Seq ID No. 14 or Seq ID No. 15.
- the MLPA long probe of the sequence shown by Seq ID No. 14 is obtained by asymmetric PCR amplification using the undefined primer of the sequence shown by Seq ID No. 7 with the PUC18 plasmid as a template;
- the MLPA long probe of the sequence shown by ID No. 15 was obtained by asymmetric PCR amplification using the undefined primer of the sequence shown by Seq ID No. 9 with the PUC18 plasmid as a template.
- the invention also discloses an MLPA short probe for detecting transgenic corn, the short probe comprising P1 and T1 segments in sequence from 5, end to 3, and the P1 is a binding region of the MLPA universal primer pair, T 1 is a detection region that matches the detection target sequence; the P 1 contains a sequence shown by Seq ID No. 16, and the T1 contains a sequence of Seq ID No. 17 or Seq ID No. 18; Seq ID No .16: 5'-GGGTTCCCTAAGGGTTGGA-3'
- Seq ID No. 17 5 '-CGAAGGACGAAGGACTCTAACGTTTAACATC-3 'Seq ID No. 18: 5 '-GGATCAGArTGTOGTITCCCGiXTrCAGTITAAACAG-S '.
- the MLPA short probe for detecting transgenic corn has a sequence represented by Seq ID No. 19 or Seq ID No. 20.
- the invention also discloses an MLPA detecting method for transgenic corn, the detecting method Including hybridization using the MLPA long probe and short probe provided by the present invention using the DNA sequence of the transgenic maize line as a template.
- the DNA sequence of the transgenic maize line defined in the present invention, is unique to the transgenic maize line and can be used to identify a particular sequence of the transgenic maize line; that is, the DNA sequence can be detected in corn or transgenic corn. It was concluded that the tested corn or the transgenic corn sample was a transgenic maize of the line or a transgenic maize containing the line.
- the MLPA short probe of the sequence shown by Seq ID No. 19 is used in combination with the MLPA long probe of the sequence shown by Seq ID No. 14, and the DNA sequence of the transgenic maize MON810 strain is used as a template for hybridization.
- the MLPA short probe of the sequence shown by Seq ID No. 20 is used in combination with the MLPA long probe of the sequence shown by Seq ID No. 15, and the DNA sequence of the transgenic maize MON88017 strain is used as a template for hybridization.
- MLPA testing For its MLPA testing.
- the detecting method further comprises performing PCR amplification on a long probe and a short probe which are connected by hybridization using a pair of universal primers, wherein the upstream/downstream primers of the universal primer respectively contain a Seq ID Sequences shown in No. 16 and Seq ID No. 1.
- the basic functions of amplifying the probe sequence after MLPA hybridization can be achieved by performing a few base substitutions, additions or deletions based on the universal primer sequences disclosed in the present invention. .
- the detecting method further comprises detecting by using an MLPA detecting probe of a transgenic maize endogenous gene, wherein the detecting probe comprises a sequence represented by Seq ID No. 21 and Seq ID No. 22, respectively.
- the 5, end of the sequence probe shown by Seq ID No. 22 is phosphorylated;
- P2 Section I It will be understood by those skilled in the art that, based on the short probe sequence disclosed by the present invention, the P1 segment or the P2 segment is at both ends or in the middle, the T1 segment is 5, the end or the middle, the T2 segment is 3, or Substitution, addition or deletion of several bases in the middle can still achieve its basic function as a short probe for MLPA detection. Due to the adoption of the above technical solutions, the beneficial effects of the present invention are:
- the MLPA long probe preparation method of the invention can obtain the MLPA long probe which meets the test requirements by using the laboratory conventional techniques such as asymmetric PCR amplification, enzymatic cleavage, gel electrophoresis and gelation recovery.
- the operation unit is simple and low-cost, and can be carried out in a general laboratory; the problem that the application of the MLPA detection method is limited due to difficulty in preparation of a long probe and high cost is solved. It laid the foundation for the promotion and application of MLPA detection technology.
- the invention ingeniously sets a restriction endonuclease cleavage site in the asymmetric PCR amplification product sequence, and after the asymmetric PCR product is subjected to enzymatic cleavage treatment, the gel electrophoresis and the gelation recovery of the cartridge can be performed. Separating the long probe effectively reduces the recovery and purification of the long probe, which greatly reduces the production cost and makes the whole process more convenient.
- the MLPA long probe and the MLPA short probe of the transgenic maize provided by the invention can be used for the detection of transgenic corn, and lay a foundation for high-throughput MLPA detection of transgenic corn.
- the method for detecting GMPA of transgenic corn lays a foundation for multi-target detection of transgenic corn, and the detection method has the advantages of good expansibility and specificity, and provides a single, convenient, effective and reliable high detection for transgenic corn.
- the flux detection method is especially suitable for inspection and quarantine departments.
- FIG. 1 is a schematic view showing the preparation of a long probe of MLPA and a long probe prepared by the method of the present invention, wherein the primer for amplification is a PUC18 plasmid, P is phosphorylated, and T2 is a region specifically binding to the detection target sequence.
- UT1 and UT2 are regions that bind to the PUC18 plasmid, P2 is a universal primer binding region, and UT is an insertion sequence inserted into a long probe in the UT1 and UT2 amplification intervals;
- FIG. 2 is a schematic diagram of MLPA detection in an embodiment of the present invention, wherein the hybrid-ligated template is a transgenic maize detection target sequence, P1 is a universal primer binding region of a short probe, and T1 is a short probe-target sequence-specific binding region, and T2 is The long probe has a specific binding region to the target sequence, UT is the insertion sequence of the long probe, and P2 is the binding region to the universal primer in the long probe; MON810, NK603, MON863, 89034, 88017, MIR604, GA21, BT11, 59122, 3272, CBH351, LY038, for the corresponding detection of transgenic maize lines MON810, NK603, MON863, MON89034, MON88017, MIR604, GA21, BT11, MON59122, Electrophoresis results of long probes of MON3272, CBH351, and LY038;
- Figure 4 is a MLPA detection result of transgenic maize MON810 and MON88017 in the present invention, wherein 1 is a detection signal of corn endogenous gene Zein 91 bp, 2 is a detection signal of maize line MON810 170 bp, 3 is a detection signal of maize line MON88017 252 bp 4-12 are molecular weight standards of 75 bp, 100 bp, 139 bp, 150 bp, 160 bp, 200 bp, 250 bp, 300 bp, and 340 bp, respectively. detailed description
- the basic idea of the present invention is to insert a sequence of MLPA detection that does not affect the target sequence into a long probe using asymmetric PCR to meet the need to prepare long probes of different lengths.
- the present invention provides a method for preparing a MLPA long probe, which comprises asymmetric PCR amplification using a primer pair, which is a sequence unrelated to the detection of a target sequence, and recovers single-stranded DNA in an asymmetric PCR amplification product.
- one primer of the primer pair includes, from 5, end to 3, a segment that matches the detection target sequence and a segment that matches the template; the primer pair The other primer, from 5, end to 3, in turn includes a segment that matches the MLPA universal primer and a segment that matches the template.
- the MLPA long probe is located downstream of the target sequence when hybridizing with the detection target sequence, it is necessary to phosphorylate the long probe 5, the end; and, in the absence of, the asymmetric PCR of the present invention
- the medium-and non-limiting primers are primers from 5, end to 3, and the ends include a segment matching the detection target sequence and a primer matching the template, and the 5th end is phosphorylated. Modification, and the "other primer” is a defined primer; therefore, the prepared long probe has a phosphorylation modification at its 5th end, and includes T2, UT, and P2 regions from 5 to 3, and at the end. Segment (Fig. 1), wherein T2 is the detection region that matches the detection target sequence, UT is the insertion sequence unrelated to the detection target sequence, and P2 is the binding region of the MLPA universal primer pair.
- the structure of the undefined primers and the defined primers in the primer pair will change accordingly.
- the non-limiting primers are from 5, end to 3, and the end includes the "other primer” of the segment matching the MLPA universal primer and the segment matching the template.
- the prepared long probe from 5, end to 3 will in turn comprise P1, UT and T1 segments, where UT is the region between the UT1 region and the UT2 region on the template that is inserted into the long probe, T1 is the area that matches the detection target.
- the structure of the short probe will change accordingly.
- the short probe needs to be phosphorylated at its 5th end during chemical synthesis, and its sequence includes the T2 and P2 segments from 5, end to 3, and in turn.
- T2 is the region that matches the detection target sequence
- P2 is the region that matches the MLPA universal primer.
- the template for asymmetric PCR in the present invention is a sequence that is not related to the detection target sequence.
- the primary consideration of the selection of the template is that after inserting or partially inserting the sequence of the template into the long probe, the inserted sequence does not cause a mismatch with the detection target sequence that affects the MLPA detection; secondly, it must be considered
- the insertion sequence does not cause a secondary structure or a tertiary structure that is detrimental to the long probe from hybridizing to the detection target sequence.
- the preferred use of the PUC18 plasmid in the present invention is a template for asymmetric PCR.
- a double-stranded DNA fragment is amplified.
- one design of the present invention is to design at least one restriction endonuclease cleavage site in the asymmetric PCR amplification product, and after the amplification is completed, the amplification product is subjected to amplification.
- the single-stranded DNA that is, the MLPA single-stranded long probe, can be recovered by excision treatment to excise the double-stranded DNA therein, followed by gel electrophoresis and gel recovery of the cartridge.
- Asymmetric PCR amplification reagent 10 X high fidelity PCR buffer, 2.5 mmol/L dNTP mixture, 50 mmol/L MgS04 solution, ⁇ /L upstream primer, ⁇ ⁇ /L downstream primer, 5 ⁇ / ⁇ PlantinumTaq enzyme high fidelity DNA polymerase, ⁇ g/ ⁇ PUC18 plasmid solution, sterile distilled water;
- Electrophoresis detection reagent Takara DL 500 molecular weight marker, 6 x Loading Buffer, lOmg/mL ethidium bromide (EB), agarose, 1 TAE buffer;
- PCR product purification kit QIAquick PCR Purification kit (QIAGEN);
- PCR instrument Biometra T
- electrophoresis instrument BioRad 300Xi type
- UV cross-linking instrument Spectronics, XJ-1000
- gel image analyzer CEE, GAS7001X
- micro-ultraviolet spectrophotometry ND-3300 NANOdrop
- ABI3100 sequencer ABI3100 sequencer.
- the upstream primer of the long probe was prepared according to the specific sequence of the transgenic maize line and the PUC18 plasmid design, such that the 5th end of the upstream primer is a sequence with a phosphorylated modification complementary to the specific sequence of the transgenic maize line, and the 3 end contains The sequence complementary to the PUC18 plasmid shown by Seq ID No. l; and the downstream primer of the long probe is designed according to the universal primers for MLPA detection and the PUC18 plasmid, such that the 5' end of the downstream primer contains the MLPA universal primer binding site. 3, the end contains a sequence complementary to the downstream sequence of the PUC18 plasmid.
- the present invention separately designed primer pairs for the asymmetric PCR amplification of MLPA long probes for transgenic maize lines MON810 and MON88017.
- the amplification primer pair 1 for detecting the long probe 1 of the transgenic maize line MON810 includes the upstream primer (Primer810-1) and the downstream primer (Primer810-2); the amplification primer pair 2 of the long probe 2 of the transgenic maize line MON88017 Includes upstream primers (Primer88017-1) and downstream primers (Primer88017-2) (Table 1).
- the above primers were synthesized in Baosheng Bioengineering Co., Ltd. Table 1 Primers for asymmetric PCR
- the total volume of the PCR reaction solution is 50 ⁇ which includes: 10 ⁇ high-fidelity PCR buffer 5 L, 2.5 mmol/L dNTP mixture 4 L, 50 mmol/L MgS0 4 5 ⁇ L, ⁇ /L upstream primer 25, 1
- the PCR reaction conditions were: pre-denaturation at 94 °C for 1 min, and then into 35 cycles: denaturation at 94 °C for 20 sec, annealing at 65 °C for 30 sec, extension at 72 °C for 20 sec, and extension at the final 72 °C for 10 min after completion of the cycle.
- step C) adding the mixed sample of step A) to the QIAquick column, centrifuging for 30 to 60 sec, and discarding the filtrate;
- step D) Add 0.75mL Buffer PE to the QIAquick column of step C), centrifuge for 30-60 sec, discard the filtrate, and centrifuge for lmin;
- the purified asymmetric PCR amplification product was digested with Hindlll restriction enzyme, and the total volume of the digestion reaction solution was 5 ( ⁇ L, including: the above purified asymmetric PCR amplification product 44 ⁇ 75 ⁇ , 10 x Hindlll
- the buffer solution was 5 ⁇ , 9 ⁇ / ⁇ of Hindlll enzyme 0 ⁇ 25 ⁇ .
- the above-mentioned enzyme digestion reaction solution was mixed, and then treated at 37 ° C for 1 hour.
- step D) adding isoamyl alcohol in an amount of 1 : 1 of tape (mg): isoamyl alcohol (mL); E) transferring the solution of step D) into a QIAquick spin column, centrifugation at 13,000 rpm for 60 sec;
- the present invention also prepared long probes for detecting transgenic maize lines NK603, MON863, MON89034, MIR604, GA21, BT11, MON59122, MON3272, CBH351, LY038, and all prepared MLPA long probes were subjected to agarose Gel electrophoresis, qualitatively detecting whether the length of each probe is consistent with the expected.
- the agarose gel electrophoresis was carried out by electrophoresis on a gel machine for 20-60 min using a 3% gel. The results showed that the length of the MLPA single-stranded long probe prepared by the present invention was all as expected, and the length of the probe was increased by a gradient of about 20 bp, as shown in Fig. 3.
- the detection principle is that the fluorescent dye in the Quant-iTTM ds BR DNA Assay kit can bind to DNA and can detect the light absorption value of ND-3300 under the blue light of 523 ⁇ 20nm, which can be compared by the standard curve.
- the concentration of the DNA sample was obtained and the range of detection was 10-5000 ng/L.
- concentration of the MLPA long probe prepared in the present invention is shown in Table 2. Table 2 probe concentration
- Probe name Probe mass concentration ( ng / ⁇ ⁇ ⁇ )
- Probe molar concentration ( fmol / L )
- the MLPA reaction product was analyzed by ABI3100 sequencer. The results showed that MON810, MON88017 and the endogenous gene Zein all had amplification signals.
- MON810 has a 170bp amplification signal
- MON88017 has a 252bp amplification signal
- the endogenous gene Zein has a 91bp amplification signal (Fig. 4), which is consistent with the theoretical length. It proves that the prepared MLPA long probe meets the design requirements and is available. Tested in MLPA.
- Probe8801 5 '-GGGTTCCCTAAGGGTTGGAGGAT 20 7-1 CAGATTGTCGTTTCCCGCCTTCAGTT
- the short probe and the long probe are ligated using a ligase.
- the total volume of the reaction solution is 20 ⁇ which includes 1.5 L of Ligase-65 buffer A, 1.5 ⁇ L of Ligase-65 buffer B, 0.5 L of Ligase-65 ligase, 12.5 L of sterilized distilled water, and finally the addition step (1).
- the ligation reaction product of the above step (2) is subjected to PCR amplification.
- the total volume of the reaction solution is 25 ⁇ , which includes: SALSA PCR buffer 2 L, step (2) 5 ⁇ of the reaction product, 13 ⁇ of sterilized distilled water, lOpmol ⁇ L of MLPA universal primer l L, DNA polymerase dilution buffer ⁇ , 5 ⁇ / ⁇ DNA polymerase 0.25 L, sterilized distilled water 2.75 L.
- PCR reaction conditions were as follows: 35 cycles directly: denaturation at 95 °C for 30 s, 60 °C for 30 s, 72 °C for 60 s, and 72 °C for 20 min after completion of the cycle. (4) PCR products
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Abstract
本发明公开了一种MLPA长探针的制备方法、转基因玉米MLPA长探针和短探针以及转基因玉米的MLPA检测方法。本发明的MLPA长探针采用不对称PCR扩增、酶切、凝胶电泳及切胶回收单链DNA等技术制备。
Description
MLPA长探针制备方法、 转基因玉米 MLPA长探针及检测方法 技术领域
本发明涉及核酸分子检测领域, 特别是涉及一种用于 MLPA检测技 术的长探针的制备方法, 由此方法制备的用于转基因玉米 MLPA检测的 长探针, 以及转基因玉米的 MLPA检测。 背景技术
目前基因检测以 PCR技术为主, 检测快速、 灵敏度高、 结果准确、 可靠。 然而, PCR方法单管只分析一个基因, 效率低。 当前要对如众多 转基因品种和品系逐一筛查, 工作量太大, 成本高。 因此, 基因检测急 需一种高通量检测方法。
常见的高通量基因检测技术有基因芯片、 多通道毛细管电泳和 DHPLC分离技术等。然而,这些方法一般只能进行"单对多"的检测(单 样品对多项目 ), "多对多" 方式的检测 (多样品对多项目 ) 能力有限, 其有限高通量的发挥还取决于上机样品所含被检目标基因数。 为一次性 获得多目标 DNA片段, 人们采用多重 PCR法, 但引物间相互干扰和引 物多聚体使该技术检测基因数目很难超过 10个。
多重连接依赖探针扩增技术 ( Multiplex Ligation dependent Primers Amplification MLPA )由荷兰的 Dr. Schouten JP于 2002年4艮道, 最初应 用于医学检测目的。 其原理是针对不同的感兴趣基因位点设计长度各不 相同的探针对, 探针对两序列的一端具基因特异性, 它们与各自目标基 因区域复性后仅留一缺口, 于此同时所有探针对中与目的基因不杂交的 一端都接有相同的碱基序列(既通用序列)用于 PCR, 这样当探针对与目 标区复性并在连接酶的作用下相连而本身成为 PCR模板 DNA, 并由一 对公用引物扩增而以信号放大, 由于针对不同的感兴趣基因位点设计的 探针对长度各不相同, 经分离 PCR产物大小(不须测序)便可知道是否 有目标基因的存在, 在并能进行相对定量分析。
MLPA技术包括探针的设计、 探针和靶序列 DNA进行杂交, 之后 通过连接、 PCR扩增, 产物通过琼脂糖凝胶电泳或毛细管电泳分离及数 据收集等过程。 具有经济(不需昂贵设备)、 特异性高 (探针复性及连接 酶识别)及高通量 (单管可测多达 40 多个基因)的特点。 此外, 该法检测
所针对的基因目标区可短至 40-50bp,特别适于 DNA 高度降解样品的检 测。 至今, MLPA技术已应用于很多领域, 如单核苷酸多态性和基因突 变检测、 基因片段缺失和重复、 染色体数目异常、 基因曱基化检测及 mRNA分析等等。
以上 MLPA技术原理显示, 多基因位点凭其最终 PCR扩增片段长 度的不同而相互区别。 为了能清晰分辨不同基因位点 PCR 扩增片段 DNA, 特别是在采用低分辨率的琼脂糖凝胶电泳分析 MLPA产物时, 必 须拉开各扩增片段的差距。 因此, 在单链探针设计和制备时必须将探针 之间的大小拉开, 随着被检测目的基因的增加, 单链探针的长度也要增 加, 而单链长探针的制备则是难点。
单链探针制备最筒单的方法是采用化学合成法, 但是, 当单链探针 超过 lOObp时, 化学合成法则不合适, 因为出现合成错误的概率大大增 加, 合成的产量也大大降低。 为克服单链探针制备的困难, 发明 MLPA 的荷兰公司 MRC-Holland开发了基于一套 M13载体的单链探针制备方 法, 其原理就是将各 M13 载体的大小不同的无关序列或无关的模板 ( Unrelated Template, UT )引入单链探针从而获得长度不同的单链探针。 该单链探针生物方法非常繁瑣, 不仅需要基因克隆、 病毒转染、 质粒提 取等过程, 还必须购买一套昂贵的 M13载体, 此外, 操作 M13病毒极 易发生污染。 为垄断 MLPA应用市场, 现在荷兰公司 MRC-Holland不再 出售 M13载体, 因此, 单链长探针的制备急待克服。 发明内容
本发明的目的是针对上述 MLPA长探针生物制备方法繁瑣的问题, 提供一种筒单、 无污染、 高效的 MLPA长探针制备方法。
本发明的另一目的是提供一种用于转基因玉米 MLPA检测的长探 针、 短探针以及转基因玉米的 MLPA检测方法。
为了实现上述目的, 本发明采用了以下技术方案:
本发明公布了一种 MLPA长探针的制备方法, 包括采用引物对以模 板进行不对称 PCR扩增, 然后用限制性内切酶处理不对称 PCR扩增产 物, 凝胶电泳经过酶切处理的不对称 PCR扩增产物, 切胶回收不对称 PCR扩增产物中的单链 DNA, 即得到 MLPA长探针; 所述模板为与检 测靶标序列无关的序列,所述不对称 PCR扩增产物的序列内包括有多克
隆位点, 所述限制性内切酶与多克隆位点对应; 所述引物对的一条引物 从 5,端到 3,端依次包括与检测靶标序列相匹配的区段和与所述模板相匹 配的区段;所述引物对的另一条引物从 5,端到 3,端依次包括与 MLPA通 用引物相匹配的区段和与所述模板相匹配的区段。
本发明中的 MLPA 是指多重连接探针扩增技术 ( multiplex ligation-dependent probe amplification, MLPA ), MLPA长探针是指现有 技术中由 M13噬菌体衍生法制备的那条探针。所述模板是需要通过不对 称 PCR插入或部分插入到长探针中的序列, 因此, 只要是与需要检测的 靶标序列没有同源关系, 或同源关系比较低, 或序列差异性很大, 并且 不会对长探针用于 MLPA检测造成不利影响的序列即可。 所述检测靶标 序列是指 MLPA检测对象的核苷酸序列, 即需要检测的制定样品的核苷 酸序列。 所述回收是指从不对称 PCR中分离获得单链 DNA的过程。 所 述 MLPA通用引物是指在 MLPA长探针和短探针的 5,端都具有的一段与 检测靶标序列无关的序列, 用于在 MLPA杂交连接成功后对链接起来的 探针进行 PCR扩增。所述多克隆位点为具有至少一个限制性内切酶酶切 位点的 DNA序列。 所述限制性内切酶处理, 即采用与该多克隆位点所 含有的酶切位点对应的内切酶进行。
本发明优选的实施方式中, 所述引物对中从 5,端到 3,端依次包括与 检测靶标序列相匹配的区段和与所述模板相匹配的区段的一条引物为不 对称 PCR中的非限定引物, 另一条引物为限定引物; 所述非限定引物的 5,端具有磷酸化修饰。 所述非限定引物是指不对称 PCR中用量相对较多 的那条引物, 限定引物是指用量相对较少的那条引物。 不对称 PCR产物 中, 所产生的单链 DNA即是由非限定引物所引导的。
本发明的优选实施方式中, 所述模板为 PUC18质粒, 所述限制性内 切酶包括 HindIII、 EcoR l中的至少一种。
本发明的优选实施方式中,所述非限定引物为不对称 PCR中的上游 引物, 所述限定引物为下游引物; 所述上游引物位于 PUC18质粒多克隆 位点的左侧, 含有 Seq ID No .2所示序列;
Seq ID No.2: 5 '-CGCCAGGGTTTTCCCAGTCACGAC-3 ' 0 作为本发明的一种优选的实施方式,所述上游引物中与 PUC18质粒 结合的区段均相同, 且位于质粒多克隆位点的左侧; 而下游引物则在 PUC 18 质粒多克隆位点的下游根据需要插入长探针的序列长度进行设
计。
本发明还公布了一种转基因玉米的 MLPA长探针,所述 MLPA长探 针的 5,端带有磷酸化修饰, 从 5,端到 3,端依次包括 T2、 UT、 P2区段, 所述 T2为与检测靶标序列匹配的检测区域, UT为与检测靶标序列无关 的插入序列, P2为 MLPA通用引物对的结合区域; 所述 P2含有 Seq ID No.11所示序列;
所述 T2含有 Seq ID No.3所示序列, 所述 UT含有 Seq ID No.12所 示序列,
或者所述 T2含有 Seq ID No.5所示序列,所述 UT含有 Seq ID No.13 所示序列;
Seq ID No.3: 5 '-CTTTGCCATTGCCCAGCTATCTGTCACTTTATTGT-3 '
Seq ID No.5: 5' -AGTCGGGTTTGGATGGTCAACTCCGGCATACTG-3 '
Seq ID No.11 : 5 ' -TCTAGATTGGATCTTGCTGGCGC-3 '
Seq ID No.12:
5, -CGCC AGGGTTTTCCCAGTC ACGAC- Seq ID No .2
GTTGTAAAACGACGG-CCAGTGCCAAGCTTGCATGCCTG-3 '
Seq ID No.4的互补配对位点
Seq ID No.13 :
5, -CGCC AGGGTTTTCCCAGTC ACGAC- Seq ID No.2
CATAGCTGTTTCCTGTGTGAAATTG-3 '
Seq ID No.6的互补配对位点
本领域技术人员熟知, MLPA检测中长探针的 5,端是保证其检测特 异性的关键, 因此, 本领域技术人员可以理解, 在上述公布的长探针序 列的基础上, 在所述 T2的 3,端或者在 UT或 P2的两端或中间替换、 添 加或删减数个碱基, 仍可以实现本发明所述长探针的基本功能。
本发明的优选实施方式中, 上述 MLPA长探针的制备方法包括, 采 用引物对以 PUC18质粒为模板进行不对称 PCR扩增, 回收扩增产物中 的单链 DNA, 即 MLPA长探针; 所述引物对由非限定引物和限定引物 组成, 所述非限定引物的 5,端带有磷酸化修饰;
所述非限定引物从 5,端到 3,端依次包括 T2和 UT1区段,T2为与检 测靶标序列匹配的检测区域, UT 1为与不对称 PCR模板相匹配的区域; 所述限定引物从 5,端到 3,端依次包括 Ρ2,和 UT2区段; Ρ2,为 MLPA通 用引物相匹配的区域, UT2 为与不对称 PCR模板相匹配的区域; 所述 Ρ2,含有 Seq ID No. l所示序列, 所述 UT1含有 Seq ID No.2所示序列; 所述 T2含有 Seq ID No.3所示序列, UT2含有 Seq ID No.4所示序 列,
或者 T2含有 Seq ID No.5所示序列, UT2含有 Seq ID No.6所示序 列;
具体的, 所述非限定引物含有 Seq ID No.7所示序列, 所述限定引 物含有 Seq ID No.8所示序列;
或者所述非限定引物含有 Seq ID No.9所示序列, 所述限定引物含 有 Seq ID No.10所示序列;
Seq ID No. l : 5 '-GCGCCAGCAAGATCCAATCTAGA-3 '
Seq ID No.4: 5'-CAGGCATGCAAGCTTGGCACTGG-3'
Seq ID No.6: 5 '-CAATTTCACACAGGAAACAGCTATGA-3 '
Seq ID No.7:
5 ' -CTTTGCCATTGCCC AGCTATCTGTCACTTTATTGT-
Seq ID No.3
CGCCAGGGTTTTCCCAGTCACGAC-3 '
Seq ID No.2
Seq ID No.8:
5, -GCGCC AGCAAGATCCAATCTAGA- Seq ID No. l
CAGGCATGCAAGCTTGGCACTGG-3 '
Seq ID No.4
Seq ID No.9:
5, - AGTCGGGTTTGGATGGTCAACTCCGGC ATACTG-
Seq~ID No.5
CGCCAGGGTTTTCCCAGTCACGAC-3 '
Seq ID No.2
Seq ID No.10:
5, -GCGCC AGCAAGATCCAATCTAGA- Seq ID No.l
CAATTTCACACAGGAAACAGCTATGA-3,。
Seq ID No.6
本发明中, 不对称 PCR扩增出 MLPA长探针的方式是, 由 T2和 UT1区段构成的非限定引物, 和由 P2'和 UT2区段构成的限定引物, 在 不对称 PCR时,引物的 UT1或 UT2分别与不对称 PCR的模板,即 PUC18 质粒匹配, 然后进行扩增, 随着扩增的进行, 扩增产物中会具有两条引 物各自 5,端的 T2和 P2,。 由于长探针 5,端需要进行磷酸化修饰, 因此, 不对称 PCR扩增获得单链 DNA的非限定引物的 5,端进行了磷酸化修饰。 本领域技术人员可以理解, 本发明上述公布的引物对序列, 只要能够基 本实现以 PUC18质粒为模板进行不对称 PCR, 在 UT1或 UT2或 P2,两 端或中间、 T2中间、 T2和 UT1之间, 或者 P2,和 UT2之间替换、 添加 或减少数个碱基同样能够实现本发明所要求的基本功能。
本发明的优选实施方式中, 所述的检测转基因玉米的 MLPA长探针 具有 Seq ID No.14或者 Seq ID No.15所示序列;
Seq ID No.14:
5 ' -CTTTGCCATTGCCC AGCTATCTGTCACTTTATTGT-
Seq ID No.3
|Seq ID No. l2|
TGCCAAGCTTGCATGCCTG-TCTAGATTGGATCTTGCTGGCGC-3
Seq ID No. l2| Seq ID No.11
Seq ID No.15:
5 , -AGTCGGGTTTGGATGGTCAACTCCGGCATACTG-
Seq ID No.5
|Seq ID No. l3|
|Seq ID No. l3|
|Seq ID No.13
GTGAAATTG-TCTAGATTGGATCTTGCTGGCGC-3 ' ,
|Seq ID No.13 |Seq ID No.11
本发明的实施方式中, 具体的, Seq ID No.14所示序列的 MLPA长 探针由 Seq ID No.7所示序列的非限定引物以 PUC18质粒为模板进行不 对称 PCR扩增获得; Seq ID No.15所示序列的 MLPA长探针由 Seq ID No.9所示序列的非限定引物以 PUC18质粒为模板进行不对称 PCR扩增 获得。
本发明还公布了一种检测转基因玉米的 MLPA短探针, 所述短探针 从 5,端到 3,端依次包括 P1和 T1区段, 所述 P1为 MLPA通用引物对的 结合区域, T 1为与检测靶标序列匹配的检测区域; 所述 P 1含有 Seq ID No.16所示序列,所述 T1含有 Seq ID No.17或者 Seq ID No.18所示序歹' J ; Seq ID No.16: 5'-GGGTTCCCTAAGGGTTGGA-3'
Seq ID No.17: 5 '-CGAAGGACGAAGGACTCTAACGTTTAACATC-3 ' Seq ID No.18: 5 ' -GGATCAGArTGTOGTITCCCGiXTrCAGTITAAACAG-S '。
本发明的实施方式中, 所述的检测转基因玉米的 MLPA短探针具有 Seq ID No.19或 Seq ID No.20所示序列;
Seq ID No.19:
5, -GGGTTCCCTAAGGGTTGGA- Seq ID No.16
CGAAGGACGAAGGACTCTAACGTTTAACATC-3'
Seq ID No.17
Seq ID No.20:
5, -GGGTTCCCTAAGGGTTGGA- Seq ID No.16
GGATCAGATTGTCGTTTCCCGCCTTCAGTTTAAACAG-3 '。
Seq~ID No.18
本领域技术人员熟知, MLPA检测中短探针的 3,端是保证其检测特 异性的关键, 因此, 本领域技术人员可以理解, 在上述公布的短探针序 列的基础上, 在所述 T1的 5,端或者在 P1的两端或中间替换、 添加或删 减数个碱基, 仍然可以实现本发明所述短探针的基本功能。
本发明还公布了一种转基因玉米的 MLPA检测方法, 所述检测方法
包括采用本发明提供的 MLPA 长探针和短探针以转基因玉米品系的 DNA序列为模板进行杂交。 所述转基因玉米品系的 DNA序列, 在本发 明中的定义为该转基因玉米品系所特有的, 可用于鉴定该转基因玉米品 系的特殊序列; 即在玉米或转基因玉米中检测到该 DNA序列, 就可以 得出结论认为所检测的玉米或该转基因玉米样品为该品系的转基因玉米 或者含有该品系的转基因玉米。
本发明的实施方式中, Seq ID No.19所示序列的 MLPA短探针与 Seq ID No.14所示序列的 MLPA长探针配套使用, 以转基因玉米 MON810 品系的 DNA序列为模板进行杂交, 用于其 MLPA检测; Seq ID No.20 所示序列的 MLPA短探针与 Seq ID No.15所示序列的 MLPA长探针配套 使用, 以转基因玉米 MON88017品系的 DNA序列为模板进行杂交, 用 于其 MLPA检测。
本发明优选的实施方式中, 所述检测方法还包括采用一对通用引物 对杂交后连接起来的长探针和短探针进行 PCR扩增,所述通用引物的上 游 /下游引物分别含有 Seq ID No.16和 Seq ID No. l所示序列。 本领域技 术人员可以理解, 在本发明公布的通用引物序列的基础上, 进行数个碱 基的替换、 添加或删减, 都能够实现对 MLPA杂交连接后的探针序列进 行扩增的基本功能。
本发明的优选实施方式中, 所述检测方法还包括采用转基因玉米内 源基因的 MLPA 检测探针进行检测, 所述检测探针分别含有 Seq ID No.21和 Seq ID No.22所示序列, Seq ID No.22所示序列探针的 5,端带 有磷酸化修饰;
Seq ID No.21 :
5, -GGGTTCCCTAAGGGTTGGA-
CGCGTGCGTTTGTGTGGATTGT-3 '
Ιτι区段 I
Seq ID No.22:
5, -AGGACAAGGCTCCCTATGTAGGCAAGG-
T2区段
TCTAGATTGGATCTTGCTGGCGC-3,。
|P2区段 I
本领域技术人员可以理解, 在本发明公布的短探针序列的基础上, 对其 P1区段或 P2区段两端或中间、 T1区段 5,端或中间、 T2区段 3,端 或中间进行数个碱基的替换、 添加或删减, 仍然能够实现其作为短探针 进行 MLPA检测的基本功能。 由于采用以上技术方案, 本发明的有益效果在于:
本发明的 MLPA长探针制备方法采用筒单的不对称 PCR扩增、 酶 切、 凝胶电泳以及切胶回收等实验室常规技术就可以获得符合试验要求 的 MLPA长探针。 与现有的制备方法相比, 操作筒单、 成本低廉, 在一 般的实验室均可进行; 解决了由于长探针制备困难、 成本高昂造成的 MLPA检测方法应用受到限制的问题。 为 MLPA检测技术的推广应用奠 定了基础。本发明巧妙的在不对称 PCR扩增产物序列内设置有限制性内 切酶的酶切位点, 对不对称 PCR产物进行酶切处理后, 通过筒单的凝胶 电泳和切胶回收就可以将长探针分离出来, 有效的筒化了长探针的回收 纯化, 大大降低了生产成本, 使整个操作过程更加筒便。
本发明提供的转基因玉米的 MLPA长探针和 MLPA短探针,可以用 于转基因玉米的检测, 为转基因玉米的高通量 MLPA检测奠定了基础。
本发明提供的转基因玉米 MLPA检测方法, 为转基因玉米的多靶标 检测奠定了基础, 该检测方法扩展性好、 特异性强, 为转基因玉米检测 提供了一种筒单、 方便、 有效、 可靠的高通量检测方法, 特别适合用于 检验检疫等部门。 附图说明
图 1是本发明实施例中 MLPA长探针制备示意图和制备的长探针示 意图, 其中引物扩增的模板为 PUC18质粒, P为磷酸化修饰, T2为与 检测靶标序列特异性配合的区域, UT1和 UT2为与 PUC18质粒结合的 区域, P2,为通用引物结合区域, UT为 UT1和 UT2扩增区间内的插入 到长探针中的插入序列;
图 2是本发明实施例中 MLPA检测示意图, 其中杂交连接的模板为 转基因玉米检测靶标序列, P1 为短探针的通用引物结合区域, T1 为短 探针与靶标序列特异性结合区域, T2为长探针与靶标序列特异性结合区 域, UT为长探针的插入序列, P2为长探针中与通用引物结合区域;
中 MON810、 NK603、 MON863、 89034、 88017、 MIR604、 GA21、 BT11、 59122、 3272、 CBH351、 LY038 ,为对应的检测转基因玉米品系 MON810、 NK603、 MON863、 MON89034、 MON88017、 MIR604、 GA21、 BT11、 MON59122 , MON3272 , CBH351、 LY038的长探针的电泳结果;
图 4是本发明实施例中转基因玉米 MON810和 MON88017的 MLPA 检测结果, 其中 1为玉米内源基因 Zein的检测信号 91bp, 2为玉米品系 MON810的检测信号 170bp, 3为玉米品系 MON88017的检测信号 252bp, 4-12为分子量标准分别为 75bp、 100bp、 139bp、 150bp、 160bp、 200bp、 250bp、 300bp、 340bp。 具体实施方式
本发明的基本构思就是,采用不对称 PCR将一段不影响靶标序列的 MLPA检测的序列插入到长探针中, 以满足制备不同长度的长探针的需 求。 具体的本发明提供了 MLPA长探针制备方法, 包括采用引物对以模 板进行不对称 PCR扩增, 所述模板为与检测靶标序列无关的序列, 回收 不对称 PCR扩增产物中的单链 DNA, 即得到 MLPA长探针; 所述引物 对的一条引物从 5,端到 3,端依次包括与检测靶标序列相匹配的区段和与 所述模板相匹配的区段; 所述引物对的另一条引物从 5,端到 3,端依次包 括与 MLPA通用引物相匹配的区段和与所述模板相匹配的区段。
在本发明中, 由于 MLPA长探针在与检测靶标序列杂交时, 位于靶 标序列的下游, 因此需要对长探针 5,端进行磷酸化修饰; 并且, 在不对 以, 本发明的不对称 PCR中非限定引物为引物对中从 5,端到 3,端依次 包括与检测靶标序列相匹配的区段和与所述模板相匹配的区段的一条引 物, 并且其 5,端进行了磷酸化修饰, 而所述 "另一条引物" 则为限定引 物; 因此, 制备出的长探针, 其 5,端带有磷酸化修饰, 从 5,端到 3,端依 次包括 T2、 UT、 P2区段(图 1 ), 其中 T2为与检测靶标序列匹配的检 测区域, UT为与检测靶标序列无关的插入序列, P2为 MLPA通用引物 对的结合区域。
本领域技术人员可以理解, 如果长探针在与检测靶标序列杂交时, 位于靶标序列的上游, 则不需要对其 5,端进行磷酸化修饰, 那么, 上述
引物对中的非限定引物和限定引物的结构就会发生相应的变化。具体为, 非限定引物为从 5,端到 3,端依次包括与 MLPA通用引物相匹配的区段和 与所述模板相匹配的区段的所述的 "另一条引物"。 那么, 制备出的长探 针从 5,端到 3,将依次包括 Pl、 UT和 T1区段, 其中 UT为在所述模板上 UT1 区域和 UT2区域之间的插入到长探针的区域, T1为与检测靶标相 匹配的区域。 同时, 短探针的结构也会相应的变化, 短探针在化学合成 时需要在其 5,端进行磷酸化修饰, 并且其序列从 5,端到 3,端依次包括 T2和 P2区段, T2为与检测靶标序列相匹配的区域, P2为与 MLPA通 用引物相匹配的区域。
本发明中不对称 PCR的模板是一段与检测靶标序列无关的序列。该 模板的选择, 首要考虑的因素则是, 在将该模板的序列插入或者部分插 入长探针后, 该插入序列不会与检测靶标序列产生影响 MLPA检测的错 配; 其次还必须考虑的是, 该插入序列不会对长探针造成不利于其与检 测靶标序列杂交的二级结构或三级结构。 综合各种因素, 本发明优选的 采用 PUC18质粒为不对称 PCR的模板。 另外, 在不对称 PCR扩增中, 除了扩增出预定的需要的单链长探针 DNA 以外, 还会扩增出双链的 DNA片段。 为了便于单链 DNA的回收, 本发明的一个设计构思是, 在 不对称 PCR扩增产物中设计了至少一个限制性内切酶的酶切位点,在扩 增完成后, 对扩增产物进行酶切处理, 以切除其中的双链 DNA, 然后通 过筒单的凝胶电泳和凝胶回收就可以回收获得其中的单链 DNA , 即 MLPA单链长探针。 PUC18质粒中存在大量的单一的限制性内切酶酶切 位点, 将其选为模板, 同样也是在上述发明构思下的一个最优选择。 下面通过具体实施例并结合附图对本发明作进一步详细说明。 以下 实施例仅仅对本发明进行进一步的说明, 不应理解为对本发明的限制。 实施例 1 转基因玉米 MLPA长探针的制备
1.材料和设备
( 1 )不对称 PCR扩增反应试剂: 10 X高保真 PCR緩沖液、2.5mmol/L 的 dNTP混合液、 50mmol/L的 MgS04溶液、 ΙΟμηιοΙ/L的上游引物、 Ι μηιοΐ/L的下游引物、 5υ/μ 的 PlantinumTaq酶高保真 DNA聚合酶、 \ g/μ 的 PUC18质粒溶液、 灭菌蒸馏水;
( 2 )电泳检测试剂: Takara DL 500分子量标记、 6 x Loading Buffer, lOmg/mL的溴化乙锭( EB )、 琼脂糖、 1 TAE緩沖液;
( 3 ) PCR 产物纯化试剂盒: QIAquick PCR Purification kit ( QIAGEN );
( 4 ) 凝胶回收试剂盒: QIAquick Gel Extraction kit ( QIAGEN );
( 5 ) 材料:转基因玉米品系 MON810和 MON88017;
( 6 )主要仪器设备: PCR仪( Biometra T )、 电泳仪( BioRad 300Xi 型)、 紫外交联仪 ( Spectronics , XJ-1000 )、 凝胶图像分析仪 (CEE , GAS7001X ), 微量紫外光分光光度计 ND-3300 ( NANOdrop )、 ABI3100 测序仪。
2.不对称 PCR引物设计和合成
根据转基因玉米品系的特异性序列和 PUC18 质粒设计制备长探针 的上游引物, 使得上游引物的 5,端为带有磷酸化修饰的与转基因玉米品 系特异性序列互补配对的序列, 3,端含有 Seq ID No. l所示的与 PUC18 质粒互补的序列; 并根据 MLPA检测的通用引物和 PUC18质粒设计制 备长探针的下游引物,使得下游引物的 5'端含有 MLPA通用引物结合的 位点, 3,端含有与 PUC18质粒下游序列互补配合的序列。根据上述原理, 本发明分别设计了用于不对称 PCR扩增检测转基因玉米品系 MON810 和 MON88017 的 MLPA 长探针的引物对。 其中检测转基因玉米品系 MON810的长探针 1的扩增引物对 1包括上游引物(Primer810-1 )和下 游引物 (Primer810-2 ); 测转基因玉米品系 MON88017的长探针 2的扩 增引物对 2包括上游引物( Primer88017-1 )和下游引物( Primer88017-2 ) (表 1 )。 上述引物均在宝生生物工程有限公司合成。 表 1 不对称 PCR所用引物
名称 序列 ( 5 '→3 ' ) Seq ID No.
Primer810 5'-P04-CTTTGCCATTGCCCAGCTATCTGTCACTT
7
-1 TATTGTCGCCAGGGTTTTCCCAGTCACGAC-3'
Primer810 5, -GCGCCAGCAAGATCCAATCTAGACAGGCATG
8
-2 CAAGCTTGGCACTGG-3 '
Primer880 5'-P04-AGTCGGGTTTGGATGGTCAACTCCGGCA
9
17-1 TACTGCGCCAGGGTTTTCCCAGTCACGAC-3'
Primer880 5, -GCGCCAGCAAGATCCAATCTAGACAATTTCA
10
17-2 CACAGGAAACAGCTATGA-3 '
3.不对称 PCR扩增反应
( 1 ) PCR反应液总体积 50μΙ^ 其中包括: 10x高保真 PCR緩沖液 5 L、2.5mmol/L的 dNTP混合液 4 L、50mmol/L的 MgS045μL, ΙΟμηιοΙ/L 的上游引物 25 、 1 μηιοΙ/L的下游引物 5 、 5υ/μ 的 PlantinumTaq酶 高保真 DNA聚合酶 0.4 L、 \ g/μ 的 PUC18质粒 Ιμ , 然后加灭菌蒸 馏水至反应液总体积 50μΙ^。
(2) PCR反应条件为, 先 94°C预变性 lmin, 然后进入 35个循环: 94°C变性 20sec、 65°C退火 30sec、 72°C延伸 20sec, 循环完成后最后 72 °C延伸 10min。
( 3 ) PCR 产物的纯化: PCR 产物的纯化采用 QIAGEN 公司的 QIAquick PCR Purification kit , 参考试剂盒说明书, 纯化步骤如下:
A )在 PCR产物中加入 PCR产物 5倍体积的 Buffer PBI ,混合均匀;
B )将 QIAquick column放入一个 2mL的收集管;
C )将步骤 A )的混合样品加入到 QIAquick column中,离心 30~60sec, 弃滤液;
D ) 在经过步骤 C ) 的 QIAquick column中加入 0.75mL Buffer PE, 离心 30-60sec, 弃滤液, 离心 lmin;
E ) 将 QIAquick column转移到一个新的 1.5mL的离心管上;
F)力口入 5(^L Buffer AE洗脱, 室温下放置 lmin, 离心 lmin, 收集 滤液, 即纯化的 PCR产物。
4. MLPA长探针的获得
( 1 ) 酶切反应
采用 Hindlll限制性内切酶消化经过纯化的不对称 PCR扩增产物, 酶切反应液的总体积为 5(^L, 其中包括: 上述纯化的不对称 PCR扩增 产物 44·75μ 、 10 x Hindlll緩沖液 5μ , 9υ/μ 的 Hindlll酶 0·25μ 。 将 上述酶切反应液混勾后, 37°C恒温处理 lh。
(2) 电泳及切胶回收
采用 3-4%的琼脂糖凝胶进行琼脂糖凝胶电泳约 20~60min后, 割取 预期片段大小的 DNA带, 用 QIAGEN公司提供的琼脂糖凝胶电泳回收 试剂盒 ( QIAquick Gel Extraction kit ) 回收 DNA, 参考试剂盒说明书, 具体回收步骤如下:
A) 切取含 DNA片段的胶带, 按 1: 6加入溶液 QG ( lmg凝胶加
入 30(^L溶液;);
Β ) 50°C水浴 10-20min, 涡旋 2-3次;
C )加 1( L 3mol/L的 NaAC, 混匀;
D )按胶带 (mg ): 异戊醇 (mL ) 比例 1 : 1的量加入异戊醇; E ) 将步骤 D ) 的溶液转入 QIAquick spin column中, 13000rpm离 心 60sec;
F ) 弃滤液, 再加 500μ∑溶液 QG到 QIAquick spin column 中, 13000rpm离心 60sec;
G )弃滤液,加 750μΙ^溶液 ΡΕ至 QIAquick spin column中, 13000rpm 离心 30-60sec;
H ) 弃滤液, 再 13000rpm离心 60sec;
I )将 QIAquick spin column置于一个新的 1.5mL的离心管中, 加入 50μ∑溶液 ΕΒ或水,室温静置 Imin, 8000rpm离心 Imin,即制备的 MLPA 长探针。 实施例 2 MLPA长探针检测
1. MLPA长探针凝胶电泳检测
采用上述相同的方法, 本发明还制备了检测转基因玉米品系 NK603、 MON863、 MON89034、 MIR604、 GA21、 BT11、 MON59122 , MON3272 , CBH351、 LY038的长探针, 将所有制备的 MLPA长探针进 行琼脂糖凝胶电泳, 定性检测各探针的长度是否与预期的相符合。 琼脂 糖凝胶电泳具体为, 采用 3%的凝胶, 在电泳仪上电泳 20-60min。 结果 显示, 本发明制备的 MLPA单链长探针的长度全部合乎预期, 探针的长 度呈约 20bp的梯度递增, 见图 3。
2. MLPA长探针浓度测定
为了便于确定制备的 MLPA长探针在 MLPA检测中的使用量,本发 行检测。 其检测原理是, Quant-iTTM ds BR DNA Assay kit中的荧光染料 能与 DNA结合, 并能在 523 ± 20nm的蓝光下被 ND-3300检测到光吸收 值, 通过标准曲线的比对, 即可得出 DNA样品的浓度, 检测的范围是 10-5000ng/ L。根据测得的 MLPA长探针的质量浓度,可以推导出 MLPA 长探针的摩尔浓度, 计算公式为, 摩尔浓度=质量浓度 /分子质量, 其中
分子质量=碱基个数> < 324.5g/moL本发明制备的 MLPA长探针的浓度见 表 2。 表 2探针的浓度
探针名称 探针质量浓度( ng/μΐ^ ) 探针摩尔浓度 ( fmol/ L )
MON810 1.73 44.4
MON88017 4.31 67.77 实施例 3 转基因玉米 MLPA检测
选取上述制备的用于检测转基因玉米品系 MON810 和 MON88017 的 MLPA长探针, Probe810-2和 Probe88017-2 , 同时化学合成内源基因 Zein的 MLPA检测探针 Zein-1、 Zein-2 , 并合成检测 MON810的短探针 Probe810-1、 检测 MON88017的短探针 Probe88017-1 (表 3 ), 应用于转 基因玉米的 MLPA检测。 MLPA反应产物采用 ABI3100测序仪进行片段 分析, 结果显示, MON810、 MON88017以及内源基因 Zein都有扩增信 号。 其中 MON810有 170bp的扩增信号、 MON88017有 252bp的扩增信 号、 内源基因 Zein有 91bp的扩增信号 (图 4 ), 与理论长度相符合, 证 明制备的 MLPA长探针达到设计要求, 可用于 MLPA检测。
MLPA检测探针和通用引物
名称 序列 ( ) Seq ID No.
5 '-P04-CTTTGCCATTGCCCAGCTATC
TGTCACTTTATTGTCGCCAGGGTTTT
Probe810- CCCAGTCACGACGTTGTAAAACGAC 14
2
GGCCAGTGCCAAGCTTGCATGCCTG TCTAGATTGGATCTTGCTGGCGC-3 '
5 ' -GGGTTCCCTAAGGGTTGGACGAA
Probe810- GGACGAAGGACTCTAACGTTTAACA 19
1
TC-3 '
5 '-P04-AGTCGGGTTTGGATGGTCAA
CTCCGGCATACTGCGCCAGGGTTTT CCCAGTCACGACGTTGTAAAACGAC
Probe8801 GGCCAGTGCCAAGCTTGCATGCCTG
15
7-2 CAGGTCGACTCTAGAGGATCCCCGG
GTACCGAGCTCGAATTCGTAATCATG GTCATAGCTGTTTCCTGTGTGAAATT GTCTAGATTGGATCTTGCTGGCGC-3 '
Probe8801 5 '-GGGTTCCCTAAGGGTTGGAGGAT 20
7-1 CAGATTGTCGTTTCCCGCCTTCAGTT
TAAACAG-3,
5 ' -GGGTTCCCTAAGGGTTGGACGCG
Zein-1 21
TGCGTTTGTGTGGATTGT-3 '
5 '-P04-AGGACAAGGCTCCCTATGTA
Zein-2 GGCAAGGTCTAGATTGGATCTTGCT 22
GGCGC-3'
上游通用
5 ' -GGGTTCCCTAAGGGTTGGA-3 ' 16 引物
下游通用 5 ' -GCGCC AGCAAGATCCAATCTAGA- 1 引物 3,
MLPA的具体检测步骤如下:
( 1 )模板与探针复性
将检测转基因玉米 MON810品系的长探针 1、 短探针 1、 检测转基 因玉米 MON88017品系的长探针 2、短探针 2以及检测内源基因的 Zein- 1 和 Zein-2混合作为混合探针, 各探针的最终浓度为 10fmol L。 将转基 因玉米 MON810品系和 MON88017品系的 DNA进行等量混合作为模板 DNA, 并将模板 DNA预先进行变性处理。 反应液的总体积为 4 L, 其 中包括: 50ng/ L的预变性的模板 DNA2 L、 各探针浓度 10fmol/ L的 混合探针 0.75μΙ^、 MLPA緩沖液 0.75μΙ^、 灭菌蒸馏水 0.5μΙ^。 反应液混 匀后, 95°C变性 lmin, 60°C恒温过夜(约 10-12h)。
( 2 ) 连接反应
在模板与探针复性后, 采用连接酶将短探针和长探针连接起来。 反 应液总体积为 20μΙ^ 其中包括, 1.5 L的 Ligase - 65 buffer A , l.5μ 的 Ligase - 65 bufferB、 0.5 L的 Ligase - 65连接酶、 12.5 L的灭菌蒸馏水, 最后加入步骤 ( 1 )模板与探针复性的产物 4 L。 混匀反应液, 在 54°C 下恒温反应 15min, 然后 98°C处理 5min灭活连接酶。
(3 ) PCR扩增反应
将上述步骤 (2) 的连接反应产物进行 PCR扩增。 反应液总体积为 25μ , 其中包括: SALSA PCR buffer 2 L, 步骤 (2) 连接反应的产物 5μΙ, 灭菌蒸馏水 13μ , lOpmol^L的 MLPA通用引物 l L, DNA聚合 酶稀释緩沖液 Ιμ , 5υ/μ 的 DNA聚合酶 0.25 L, 灭菌蒸馏水 2.75 L。
PCR反应条件为, 直接进入 35 次循环: 95°C变性 30s、 60°C复性 30s、 72°C延伸 60s, 循环完成后 72°C延伸 20min。
( 4 ) PCR产物
采用 ABI 3100测序仪的片段分析功能对步骤(3 )中的 PCR产物进 行分析。 以上内容是结合具体的实施方式对本发明所作的进一步详细说明, 不能认定本发明的具体实施只局限于这些说明。 对于本发明所属技术领 域的普通技术人员来说, 在不脱离本发明构思的前提下, 还可以做出若 干筒单推演或替换, 都应当视为属于本发明的保护范围。
序列表部分
〈110〉 深圳出入境检验检疫局动植物检验检疫技术中心
〈120〉 MLPA长探针制备方法、 转基因玉米 MLPA长探针及检测方法
〈130〉 DHC1210006PCT
〈160〉 22
〈170〉 Patent ln vers ion 3. 3
〈210〉 1
〈211〉 23
〈212〉 DNA
〈213〉 人工序列
〈400〉 1
gcgccagcaa gatccaatct aga 23
〈210〉 2
〈211〉 24
〈212〉 DNA
〈213〉 人工序列
〈400〉 2
cgccagggtt ttcccagtca cgac 24
〈211〉 35
〈212〉 DNA
〈213〉 人工序列
〈400〉 3
ctttgccatt gcccagctat ctgtcacttt attgt
〈210〉 4
〈211〉 23
〈212〉 DNA
〈213〉 人工序列
〈400〉 4
caggcatgca agcttggcac tgg
〈210〉 5
〈211〉 33
〈212〉 DNA
〈213〉 人工序列
〈400〉 5
agtcgggttt ggatggtcaa ctccggcata ctg
〈210〉 6
〈211〉 26
〈212〉 DNA
〈213〉 人工序列
〈400〉 6
caatttcaca caggaaacag ctatga 26
〈210〉 7
〈211〉 59
〈212〉 DNA
〈213〉 人工序列
〈400〉 7
ctttgccatt gcccagctat ctgtcacttt attgtcgcca gggttttccc agtcacgac 59
〈210〉 8
〈211〉 46
〈212〉 DNA
〈213〉 人工序列
〈400〉 8
gcgccagcaa gatccaatct agacaggcat gcaagcttgg cactgg 46
〈210〉 9
〈211〉 57
〈212〉 DNA
〈213〉 人工序列
〈400〉 9
agtcgggttt ggatggtcaa ctccggcata ctgcgccagg gttttcccag tcacgac 57
〈210〉 10
〈211〉 49
〈212〉 DNA
〈213〉 人工序列
〈400〉 10
gcgccagcaa gatccaatct agacaatttc acacaggaaa cagctatga 49
〈210〉 11
〈211〉 23
〈212〉 DNA
〈213〉 人工序列
〈400〉 11
tctagattgg atcttgctgg cgc
〈210〉 12
〈211〉 62
〈212〉 DNA
〈213〉 人工序列
〈400〉 12
cgccagggtt ttcccagtca cgacgttgta aaacgacggc cagtgccaag cttgcatgcc 60 tg
62
〈210〉 13
〈211〉 140
〈212〉 DNA
〈213〉 人工序列
〈400〉 13
cgccagggtt ttcccagtca cgacgttgta aaacgacggc cagtgccaag cttgcatgcc 60 tgcaggtcga ctctagagga tccccgggta ccgagctcga attcgtaatc atggtcatag 120 ctgtttcctg tgtgaaattg 140
〈210〉 14
〈211〉 120
〈212〉 DNA
〈213〉 人工序列
〈400〉 14
ctttgccatt gcccagctat ctgtcacttt attgtcgcca gggttttccc agtcacgacg 60 ttgtaaaacg acggccagtg ccaagcttgc atgcctgtct agattggatc ttgctggcgc 120
〈210〉 15
〈211〉 196
〈212〉 DNA
〈213〉 人工序列
〈400〉 15
agtcgggttt ggatggtcaa ctccggcata ctgcgccagg gttttcccag tcacgacgtt 60 gtaaaacgac ggccagtgcc aagcttgcat gcctgcaggt cgactctaga ggatccccgg 120 gtaccgagct cgaattcgta atcatggtca tagctgtttc ctgtgtgaaa ttgtctagat 180 tggatcttgc tggcgc 196
〈210〉 16
〈211〉 19
〈212〉 DNA
〈213〉 人工序列
〈400〉 16
gggttcccta agggttgga 19
〈210〉 17
〈211〉 31
〈212〉 DNA
〈213〉 人工序列
〈400〉 17
cgaaggacga aggactctaa cgtttaacat c 31
〈210〉 18
〈211〉 37
〈212〉 DNA
〈213〉 人工序列
〈400〉 18
ggatcagatt gtcgtttccc gccttcagtt taaacag 37
〈210〉 19
〈211〉 50
〈212〉 DNA
〈213〉 人工序列
〈400〉 19
gggttcccta agggttggac gaaggacgaa ggactctaac gtttaacatc 50
〈210〉 20
〈211〉 56
〈212〉 DNA
〈213〉 人工序列
〈400〉 20
gggttcccta agggttggag gatcagattg tcgtttcccg ccttcagttt aaacag 56
〈210〉 21
〈211〉 41
〈212〉 DNA
〈213〉 人工序列 〈400〉 21
gggttcccta agggttggac gcgtgcgttt gtgtggattg t 41
〈210〉 22
〈211〉 50
〈212〉 DNA
〈213〉 人工序列
〈400〉 22
aggacaaggc tccctatgta ggcaaggtct agattggatc ttgctggcgc 50
Claims
1.一种 MLPA长探针的制备方法, 所述制备方法包括,
采用引物对以模板进行不对称 PCR扩增,然后用限制性内切酶处理 不对称 PCR扩增产物,凝胶电泳经过酶切处理的不对称 PCR扩增产物, 切胶回收不对称 PCR扩增产物中的单链 DNA, 即得到 MLPA长探针; 所述模板为与检测靶标序列无关的序列,所述不对称 PCR扩增产物 的序列内包括有多克隆位点, 所述限制性内切酶与多克隆位点对应; 所述引物对的一条引物从 5,端到 3,端依次包括与检测靶标序列相匹 配的区段和与所述模板相匹配的区段;
所述引物对的另一条引物从 5,端到 3,端依次包括与 MLPA通用引物 相匹配的区段和与所述模板相匹配的区段。
2.根据权利要求 1所述的制备方法, 其特征在于: 所述引物对中从 5,端到 3,端依次包括与检测靶标序列相匹配的区段和与所述模板相匹配 的区段的一条引物为不对称 PCR中的非限定引物,另一条引物为限定引 物; 所述非限定引物的 5,端具有磷酸化修饰。
3.根据权利要求 1或 2所述的制备方法, 其特征在于: 所述模板为 PUC18质粒, 所述限制性内切酶包括 HindIII、 EcoR l中的至少一种。
4.根据权利要求 3所述的制备方法, 其特征在于: 所述非限定引物 为不对称 PCR中的上游引物, 所述限定引物为下游引物; 所述上游引物 位于 PUC18质粒多克隆位点的左侧, 含有 Seq ID No.2所示序列。
5.—种检测转基因玉米的 MLPA长探针, 其特征在于: 所述长探针 的 5,端带有磷酸化修饰, 从 5,端到 3,端依次包括 T2、 UT、 P2区段, 所 述 P2含有 Seq ID No.11所示序列;
所述 T2含有 Seq ID No.3所示序列, 所述 UT含有 Seq ID No.12所 示序列,
或者所述 T2含有 Seq ID No.5所示序列,所述 UT含有 Seq ID No.13 所示序列。
6.根据权利要求 5所述的 MLPA长探针, 其特征在于: 所述 MLPA 长探针的制备方法包括, 采用引物对以 PUC18 质粒为模板进行不对称 PCR扩增, 回收扩增产物中的单链 DNA, 即 MLPA长探针; 所述引物 对由非限定引物和限定引物组成, 所述非限定引物的 5,端带有磷酸化修 饰;
所述非限定引物含有 Seq ID No.7所示序列,所述限定引物含有 Seq ID No.8所示序列;
或者所述非限定引物含有 Seq ID No.9所示序列, 所述限定引物含 有 Seq ID No.10所示序列。
7.—种检测转基因玉米的 MLPA短探针, 其特征在于: 所述短探针 从 5,端到 3,端依次包括 P1和 T1区段; 所述 P1含有 Seq ID No.16所示 序列, 所述 T1含有 Seq ID No.17或者 Seq ID No.18所示序列。
8.—种转基因玉米的 MLPA检测方法, 其特征在于: 所述检测方法 包括采用权利要求 5或 6的 MLPA长探针与权利要求 7的短探针以转基 因玉米品系的 DNA序列为模板进行杂交。
9.根据权利要求 8所述的检测方法, 其特征在于: 还包括采用一对 通用引物对杂交后连接起来的长探针和短探针进行 PCR扩增,所述通用 引物的上游 /下游引物分别含有 Seq ID No.16和 Seq ID No.l所示序列。
10.根据权利要求 8或 9所述的检测方法, 其特征在于: 还包括采用对 转基因玉米内源基因进行 MLPA检测的两条探针, 所述两条探针分别含 有 Seq ID No.21和 Seq ID No.22所示序列, Seq ID No.22所示序列探针的 5, 端带有磷酸化修饰。
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