Classical Genetics and Gene Mapping

Abstract

The search for the genetic factor associated with many important traits in chickpea has been focused on two major techniques, linkage (and QTL) mapping and candidate gene approach. Linkage mapping is the process of systematically scanning the plant genome of both intraspecific (within a species) and interspecific (across different species) populations segregating for the trait of interest using variable also known as polymorphic DNA segments or single nucleotide whose position on the genome is known, as such they are collectively called as genetic markers. Using those populations, researchers can identify genetic regions associated with or linked to the trait by observing that the affected lines share certain marker variants (i.e., alleles) located in those regions more frequently than would be expected by random chance. These regions were then often being isolated for further analysis and characterization of the responsible genes. Linkage mapping techniques have already resulted in the identification of several potential DNA regions that may contain important genes for plant and seed morphology, flower and seed color, disease resistance, and other important traits in chickpeas such as double podding, nodulation, and resistance to herbicide. The primary advantage of linkage mapping is that researchers do not need prior knowledge of the physiology underlying the traits. The candidate gene analysis will then enable the researchers to examine the validity of the genetic basis of the traits. This chapter discusses examples of linkage and gene mapping in chickpea and some potential candidate genes underlying the traits.