Genetic Diversity Studies in Indian Mustard (Brassica juncea L. Czern & Coss) Using Molecular Markers

Genetic diversity evaluation is one of the most important components of pre-breeding, which provides a clear understanding about the structure and variability inherited in a crop and thus helps in the identification of genetically diverse parents for breeding programmes. Rapeseed-mustard (RM) group of crops constitutes six economically important crops, of which five are oilseed crops and one, that is, Brassica oleracea, is an important vegetable crop. Among oilseed Brassica species, B. juncea (Indian mustard) is the most widely cultivated crop in many countries including India, Canada, Russia, China and Australia. In India, this crop contributes to more than 85% of RM acreage. Various efforts had been made in the past for genetic diversity characterization in Indian mustard germplasm and varieties using agro-morphological and biochemical markers. With the development of genomic resources in oilseed Brassica species, emphasis had been focused on using DNA/molecular markers including randomly amplified polymorphic DNA (RAPDs), inter-simple sequence repeats (ISSRs), restriction fragment length polymorphisms (RFLPs), amplified fragment length polymorphisms (AFLPs), simple sequence repeats (SSRs) and expressed sequence tags (ESTs). In this chapter, we have tried to compile various studies conducted for genetic diversity evaluation in Indian mustard using different types of molecular markers.