Legume Genomics: From Genomic Resources to Molecular Breeding

With an explosive growth rate, especially in developing countries, the world population of 7.2 billion is expected to reach 9.6 billion by 2050. There is a need to produce about 70% more food to feed this predicted population. Legumes form important constituents of a vegetarian diet and are rich sources of dietary protein (Duranti and Gius, 1997). Legumes comprise the third largest family of flowering plants and provide important sources of food, fodder, oil, and fiber products. Legume seeds typically contain 20 to 25% protein and are also a rich source of dietary fiber. In addition, legumes have the capability to fix atmospheric N2 with the help of symbiotic nitrogen fixing bacteria in root nodules, thereby reducing fertilizer use in agriculture, and the cost of nitrogen inputs by smallholder farmers in developing countries. Due to their higher protein content and other nutrients, legumes are considered important to confront malnutrition among resource-poor people in developing countries. In brief, legumes including beans (Phaseolus vulgaris), chickpea (Cicer arietinum), cowpea (Vigna unguiculata), lentils (Lens culinaris), pea (Pisum sativum), peanut (Arachis hypogaea), and soybean (Glycine max), etc. play an important role in ensuring food security, reducing poverty, improving human health and nutrition, and enhancing ecosystem resilience, especially in developing countries. Considering the importance of legumes for food and nutritional security, there have been sincere efforts toward increasing legume production. However, average global yield for legumes (0.86 t/ha) is much less than the average yield of cereals (3.54 t/ha) (FAO, 2011). Despite continuous efforts to improve productivity, crop production has witnessed severe challenges and suffers with yield loss due to several biotic and abiotic factors. Biotic factors affecting yield include aphids (Aphis craccivora), flower thrips (Megalurothrips sjostedti), pod borer (Maruca vitrata), weevil (Callosobruchus maculatus) in cowpea, rust (Phakopsora pachyrhizi), stem rot (Sclerotinia sclerotiorum), red leaf blotch (Phoma glycinicola), cyst (Heterodera glycines) in soybean, rust (Puccinia arachidis), late leaf spot (Cercosporidium personatum), early leaf spot (Cercospora arachidicola) in peanut, ascochyta blight (Ascochyta rabiei), fusarium wilt (Fusarium oxysporum), botrytis gray mold (Botrytis cinerea), dry root rot (Rhizoctonia bataticola), and pod borer (Helicoverpa armigera) in chickpea (Dauost et al., 1985; Pandey et al., 2012; Varshney et al., 2013a). Among abiotic stress drought, salinity and temperature are major yield constraints. In addition, climate changes have had a tremendous influence on crop production and productivity (Varshney et al., 2011; Lake et al., 2012). To meet food requirements and increase legume production to combat malnutrition, it is essential to develop the crop with a higher yield. However, efforts to increase legume production using conventional approaches have been happening for some time, but global production has only increased marginally during the past 50 yr (FAO, 2011). This suggests a need to develop crop varieties with a higher yield that also include environment-specific responses to stress. In this scenario, genomics-assisted breeding (GAB), that integrates the use of genomic tools Published in The Plant Genome 6 doi: 10.3835/plantgenome2013.12.0002in © Crop Science Society of America 5585 Guilford Rd., Madison, WI 53711 USA An open-access publication