MOLECULAR MARKER SYSTEMS AND THEIR UTILIZATION IN COMMON BEAN

Common bean (Phaseolus vulgaris L.; 2n = 2x = 22) is the most important edible food legume. It represents 50% of the grain legumes consumed worldwide. Traits of economic importance need to be mined for crop improvement. Morphological characters were used to select and cross the plants carrying desired combination of traits to produce new cultivars during early 19th century as it was the only available option. However, there were some major shortcomings in using morphological characters viz, development stage specific expression, sensitivity to environmental conditions, alteration in expression by epistatic and pleiotropic interactions and identification of genomic regions (QTLs) controlling quantitative traits (QTs) through conventional phenotypic evaluation was very difficult. The discovery of molecular markers in the 1980s, which are based on polymorphism in DNA sequences, was a major breakthrough towards genetic characterization of quantitative traits. Molecular markers make it possible to track the inheritance of linked segments of the genome in suitable pedigrees and significant association between molecular markers