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Isolation Strategy of Plant Functional Genes Based on DNA Molecular Markers

Date:2021/01/06 13:51:53
With the development of molecular biology, molecular marker technology is becoming more and more extensive, especially in the field of agronomy, the isolation of plant functional genes has been widely used in this technology. Future research will explore new applications of molecular marker technology and make molecular marker technology more comprehensive. Genes are DNA sequences that produce specific proteins. The separation of functional genes is of great significance. This article summarizes the separation of plant populations, the construction of DNA libraries, the construction of gene banks, the isolation and identification of target genes, and plant functions based on DNA molecular markers. Separation of genes.
There are two different ways to isolate genes, forward genetics and reverse genetics. Among them, forward genetics is to identify products or certain phenotypic mutations based on the functional identification of the target gene itself; the latter concentrates on the gene itself through specific sequences or positions in the genome. Traditional functional cloning is based on reversing the nucleotide sequence of the product of a known gene, and then designing probes or primers based on the sequence to screen clones from eDNA libraries or genomic libraries, belonging to the former category [1]. But first find the DNA molecular markers closely linked to the target gene, and then clone the target gene by "walking" or "landing" on the chromosome, which belongs to the second category of reverse genetics.
1 Application of DNA molecular markers on plants
There are many molecular markers with unique, and examples of molecular marker combinations in plants have been proposed. In a narrow sense, the concept of analytical markers is DNA markers, which can react to some different DNA fragments in the genome of organisms or populations. The concept of molecular markers can respond well to differences in genomic DNA. Commonly molecular markers are RFLP, RAPD, AFLP, SSR, ISSR, EST, etc. The EST is a molecular marker based on mRNA. The details are as follows.
DNA molecular marker technology is closely related to the development of molecular biology. Due to the discovery of DNA endonuclease and DNA recombination technology, gene location mutation, polymerase chain reaction, DNA restriction endonuclease fragment length polymorphism (Ran2), the establishment of random amplified polymorphic DNA (RAPD) and protein Engineering is playing a huge role in formulating the research results of molecular biology, the theoretical research of genetics and the practical application of biotechnology [3].
2 Isolation strategy of plant functional genes
The special genetic population of plant genomic DNA breeding is a key step for screening molecular markers closely related to target genes. The target gene must meet some basic conditions: except for the local region of the genome, the rest of the genomic DNA sequence is the same, and the polymorphic markers found between these materials can be closely linked to the target gene. Near-isogenic lines (NIL) of target genes are a group of qualified species. In view of the genetic composition of NIL, molecular markers that may show polymorphism between near-isogenic lines may be located near the two wings of the target gene.
21 Extraction Methods of Plant Genomic DNA
The extraction of plant functional genes is an operation at the genetic level. To a certain extent, there are now more mature methods. The extraction of genomic DNA is the prerequisite for DNA molecular markers. Only when the genomic DNA is extracted can the DNA molecules be further analyzed. Only by labeling can the functional genes be separated. In the extraction technology of plant genomic DNA, scientific researchers have also made more efforts and achieved more results, and more mature methods have also formed a certain system [4]. Common DNA extraction methods are: sDs method; modified SDS method; conventional CTAB method; high-salt CTAB method; modified CTAB method.
22 DNA molecular labeling methods
DNA molecular markers refer to the identification of different DNA fragments between organisms as genetic markers through techniques and methods at the DNA molecular level. Among them, DNA molecules can be divided into molecular hybridization-based polymorphisms such as RFLP (Re-strietion Fragment Lensth Polymorphism) according to different labeling methods, and PCR-based polymorphisms such as RAPD, SSR, AFLP, AP-PCR, There are 2 types of markers such as DAF. Polymerase chain reaction (PCR) is a molecular biology technique in which DNA polymerase two oligonucleotides as primers to catalyze the amplification of DNA fragments located in two primers. DNA molecular marker technology itself is a very effective method and is widely in gene mapping, and it will also play a certain role in the new stage of gene isolation and variety improvement research and analysis. Random amplified polymorphic DNA (Random Amplifi, edPolymorphic DNA, RAPD) is a DNA polymorphism detection technology independently proposed by Wil-liams (1990) and Welsh (1990) [5]. A large number of studies have shown that SSR molecular markers have simple, stable and good polymorphism. The prerequisite for the  of SSR markers is to understand the DNA sequence flanking the repetitive sequence, which limits the application of this technology, but this progress has been rapid in recent years.
The method of DNA molecular labeling mainly includes the following basic operations: separating the left and right ends of the large fragment positive clones, and then using them as probes to screen the genomic library again, and the new clones obtained are along the chromosome A kind of progress and development. The main problem that needs to be faced in the process of chromosome walking is that once some fragments that cannot be cloned need to be transmitted, the walking process will be interrupted. But in the process of continuous research, it is found that the above problems can be solved by chromosome jumping and joining. The construction of skip library and link library is mainly done by two different enzymes with a small number of recognition sites and a large number of recognition sites. The insert of the skip library is a double digested part cloned from a large fragment in the same library. Some enzymes with cleavage points produce inserts that connect to the library. These rub-ins have enzyme recognition sites and fewer cleavage points. In order to be able to get closer to the target gene, the jumping and ligation process in chromosome walking can be completed by two libraries alternately.
3 concluding remarks
DNA molecular editing has been in scientific research to achieve the isolation of a large number of plant functional genes. With the development of scientific research and the improvement of molecular level in various fields, this technology has shown great potential and bright prospect. However, there is still a big gap between China and the international leading level. Promote its application and advanced technology to bring benefits to the improvement of human living standards.

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