PCR-based Markers: A Review

Markers are becoming resourceful tools in assessing genetic diversity among genotypes. Detection and analysis of genetic variation plays an important role in understanding the molecular basis of various biological phenomena in biota and in establishing phylogenetic relationships among cultivars. A marker can be a protein molecule or a nucleotide sequence linked with a particular trait of an individual and can be employed to predict or characterise genotypic differences. Markers can be morphological, biochemical, cytological and DNA based. DNA-based markers offer several advantages over the conventional markers (morphological, biochemical, cytological) as they are independent of environmental factors, innumerable, highly polymorphic, reliable and lack pleiotropic or epistatic effects. Information provided by them can be analysed objectively; giving new direction to plant breeding programs. DNA based markers are categorised into non-PCR-based and PCR-based. Discovery, principle and applications of PCR-based markers are discussed.