An Overview of Molecular Marker Techniques

The innovation of polymerase chain reaction was a milestone in the development of DNA markers. This facilitated the development of marker based gene tags, cloning of agronomically important genes, variability studies, phylogenetic analysis, selection of wanted genotypes, etc. In Plant sciences, the advent of recombinant DNA technology and PCR (Polymerase Chain Reaction) have opened up new avenues and opportunities for the application of molecular markers in the diversified field of research and scientific investigations. The development and use of molecular markers for the detection and exploitation of DNA polymorphism is one of the most significant development in the field of molecular genetics. The presence of various types of molecular markers, and differences in their principles, methodologies, and applications require careful consideration in choosing one or more of such methods. No molecular markers are available yet that fulfill all requirements needed by researchers. According to the kind of study to be undertaken, one can choose among the variety of molecular techniques, each of which combines at least some desirable properties. This article provides detail review for different molecular marker methods: restriction fragment length polymorphism (RFLP), random amplified polymorphic DNA (RAPD), amplified fragment length polymorphism (AFLP), inter-simple sequence repeats (ISSRs), sequence characterized regions (SCARs), sequence tag sites (STSs), cleaved amplified polymorphic sequences (CAPS), microsatellites or simple sequence repeats (SSRs), expressed sequence tags (ESTs), single nucleotide polymorphisms (SNPs), and diversity arrays technology (DArT). Thus DNA markers offer several advantages over conventional phenotypic markers, as they provide data that can be analyzed objectively.