Genetic Marker - Types

Types

Some commonly used types of genetic markers are

  • RFLP (or Restriction fragment length polymorphism)
  • SSLP (or Simple sequence length polymorphism)
  • AFLP (or Amplified fragment length polymorphism)
  • RAPD (or Random amplification of polymorphic DNA)
  • VNTR (or Variable number tandem repeat)
  • Microsatellite polymorphism, SSR (or Simple sequence repeat)
  • SNP (or Single nucleotide polymorphism)
  • STR (or Short tandem repeat)
  • SFP (or Single feature polymorphism)
  • DArT (or Diversity Arrays Technology)
  • RAD markers (or Restriction site associated DNA markers)

They can be further categorized as dominant or co-dominant. Dominant markers allow for analyzing many loci at one time, e.g. RAPD. A primer amplifying a dominant marker could amplify at many loci in one sample of DNA with one PCR reaction. Co-dominant markers analyze one locus at a time. A primer amplifying a co-dominant marker would yield one targeted product. Dominant markers, as RAPDs and high-efficiency markers (like AFLPs and SMPLs), allow the analysis of many loci per experiment without requiring previous information about their sequence.

Codominant markers (RFLPs, microsatellites, etc.) allow the analysis of only a locus per experiment, so they are more informative because the allelic variations of that locus can be distinguished. As a consequence, you can identify linkage groups between different genetic maps but, for their development it is necessary to know the sequence (which is still expensive and is considered one of their down sides).

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