Towards enriching genomic resources in legumes

Abstract

Food legumes, mainly comprising dry beans, dry peas, soybean, chickpea, pigeonpea, groundnut, greengram, blackgram, cowpea, lentil and lathyrus, have considerable area under cultivation globally and these are important constituents of cereal-based vegetarian diets. Keeping in view their tremendous importance for diversification and intensification of contemporary agriculture, systematic efforts towards their genetic improvement have been undertaken with classical breeding tools, lately complemented by the use of genomic tools. These genomic tools provide comprehensive information on genes involved in biochemical pathways leading upto nutritional compounds and can be used to understand the genetics of traits of interest and consequently, helping in marker assisted breeding. During the last two decades powerful genetic and genomic tools such as establishment of genetic and physical maps, expressed sequence tags, bioinformatic tools, genome-wide sequence data, genomic and metabolomic platforms, etc. have been developed for many legume species. These efforts have led to development of large scale molecular markers, identification of various marker trait associations, construction of genetic and linkage maps, expressed sequence tags database, partial or whole genome sequences, physical and molecular maps, DNA chips and bacterial artificial chromosome (BAC) libraries. After the genome sequencing of three model species, Medicago, Lotus and Glycine, draft genome sequences have recently been made available in agronomically important food legumes, pigeonpea and chickpea while similar efforts are underway in groundnut and greengram. The new generation sequencing (NGS) and genotyping platforms such as 454/FLX sequencing and Illumina GoldenGate/Solexa have revolutionized plant genomic research as these generate millions of ESTs per run. With the increased amount of genomic resources, there are now tremendous opportunities to integrate these with the genetic resources for their widespread use in routine legume improvement programmes by integrating them with conventional breeding tools. As a result, the genomics assisted breeding (GAB) can now be successfully used in legume improvement and development of improved genotypes having improved agronomic and quality traits and resistance to biotic and abiotic stresses. This chapter discusses the developments made in development of legume genomics and their role in overall improvement of food legumes.