ABSTRACT
We can say that plant breeding is an art, science, and technology to change the genetic architecture of crop plants by using the principles of genetics in order to produce desired characteristics as per high economic values. The basic aim of genetics and plant breeding is to connect genotype to phenotype to improve the performance of crop plants. Association mapping (AM) is one of the techniques of modern plant breeding to connect plant phenotype with their genotype to define some new alleles/genes/quantitative trait loci
(QTLs) in large natural population. AM seeks specific alleles or loci linked to phenotyping differences in a trait. In short, AM can be defined as the technique of gene localization by linkage disequilibrium (LD), without cloning. Although this technique has some similarities with QTL mapping, they differ in terms of nature of population and statistical approaches. Identification and utilization of QTLs for desirable and important traits needs its tagging and mapping using molecular markers in the genome. QTLs/genes identification and mapping for desired trait is valuable for map-based cloning of the tagged genes and integrating these QTLs/genes into desirable cultivars through marker-assisted breeding (Asins, 2002; Khaing et al., 2014; Sehgal et al., 2016). Techniques of AM situate the QTLs/genes by correlating the phenotype of desired trait with genotypic data obtained using molecular markers in unstructured or loosely structured population. AM has the ability to identify and map the QTLs/genes with higher accuracy as compared to linkage-based QTL mapping therefore it is more powerful technique for marker-assisted selection, gene discovery, gene tagging, gene pyramiding, and sequence diversity with heritable phenotypic differences (Mackay and Powell, 2007).
