Molecular markers : An uprising tool for crop improvement

Molecular marker is a DNA sequence in the genome of any organism which can be located and identified. Plant breeders always prefer to remark the gene as the molecular marker, although this is not always possible. A molecular marker is nothing but a small region of DNA that shows sequence polymorphism in different individuals within a species or different species. The utility of molecular marker is based on naturally occurring DNA polymorphism and its growth in utility has greatly modified genetics and plant breeding. The DNA markers are most widely used in plant breeding programmes such as in the assessment of genetic variations within cultivars, gene mapping, transferring desirable genes for biotic and abiotic resistance. Marker-assisted selection (MAS) proves to be the most fascinating approach of molecular markers. An ideal DNA marker should be polymorphic in nature and it can be expressed in all tissues, organs, at various developmental stages. When comparing between conventional breeding approaches and molecular markers, the efficiency and effectiveness of breeding programs can be increased by molecular markers. Due to the presence of different types of molecular markers, and the variation in their principles, methodologies and mode of application, they require careful consideration in selecting one or more of such methods. With advancement in the availability of types of molecular markers, they can be used for the assessment of genetic diversity in cultivars, germplasm collection and advanced breeding material, identification of homokaryonand hybrid selection. This review article attempts to consider the current resources and novel examples where the MMs have been developed and used for the improvement of cereal crops for agronomic, food quality, disease resistance, abiotic stress tolerance traits and cytogenetic studies.