Molecular Markers

Conventionally, establishment of relationship between the genotype and phenotype through genetic analysis was considered as key to success in plant breeding. The discovery of molecular markers has changed the entire scenario of genome analysis. Coinheritance of a gene of interest and a marker suggests that they are physically close on the chromosome. A marker must be polymorphic in nature for their identification and utilization. Such polymorphism can be detected at three levels: phenotype (morphological), difference in biomolecules (biochemical), or differences in the nucleotide sequence of DNA (molecular). These markers act as a versatile tool and find their importance in taxonomy, plant breeding, gene mapping, cultivar identification, and forensic science. They have several advantages over the conventional methods of plant breeding for developing new varieties with higher rate of success. This chapter covers the basic principles and applications of various types of markers with special emphasis on molecular markers.