What are flanking markers ?

  

Flanking markers are genetic markers located adjacent to a gene or genomic region of interest. They are used in genetic mapping and molecular breeding to identify the position of a gene or quantitative trait locus (QTL) within a chromosome or genome. Flanking markers provide reference points that define the boundaries of the target region and help to narrow down its location.

1. Mapping Genomic Regions:

Flanking markers are used to map the position of genes or QTLs within a chromosome or genome. By identifying genetic markers that flank the target region, researchers can determine its approximate location.

2. Linkage Analysis:

Flanking markers are essential for linkage analysis, which involves studying the co-inheritance of genetic markers and phenotypic traits within a population. By genotyping individuals for flanking markers and the target trait, researchers can assess the degree of linkage and estimate the genetic distance between markers and the trait of interest.

3. Marker-Assisted Selection (MAS):

In breeding programs, flanking markers can be used for marker-assisted selection to indirectly select for traits of interest. Breeders genotype individuals for flanking markers linked to desirable traits and use this information to make informed breeding decisions.

4. Fine Mapping:

Flanking markers help in fine mapping, where researchers aim to narrow down the location of a gene or QTL to a smaller genomic interval. Additional markers are often developed within the region defined by the flanking markers to further refine the mapping resolution.

5. Genome Editing:

Flanking markers are useful for genome editing techniques such as CRISPR/Cas9. They provide reference points for designing guide RNAs and target specific regions for gene editing with precision.

6. Characterization of Genetic Variation:

Flanking markers are also valuable for studying genetic variation and population genetics. By comparing the allele frequencies of flanking markers among populations, researchers can infer patterns of genetic diversity, population structure, and evolutionary relationships.

Example:

Suppose researchers are interested in identifying the gene responsible for a disease trait in humans. They may genotype individuals with the disease and unaffected individuals for flanking markers located on the chromosome of interest. By comparing the marker genotypes between affected and unaffected individuals, researchers can narrow down the location of the disease gene and prioritize candidate genes within the region defined by the flanking markers.

In summary, flanking markers are genetic markers located adjacent to a gene or genomic region of interest. They play a crucial role in genetic mapping, marker-assisted selection, fine mapping, genome editing, and population genetics, providing reference points for studying the inheritance and function of genes and QTLs.