Legume Crops Phylogeny and Genetic Diversity for Science and Breeding

Economically, legumes (Fabaceae) represent the second most important family of crop plants after the grass family, Poaceae. Grain legumes account for 27% of world crop production and provide 33% of the dietary protein consumed by humans, while pasture and forage legumes provide vital part of animal feed. Fabaceae, the third largest family of flowering plants, has traditionally been divided into the following three subfamilies: Caesalpinioideae, Mimosoideae, and Papilionoideae, all together with 800 genera and 20,000 species. The latter subfamily contains most of the major cultivated food and feed crops. Among the grain legumes are some of mankind's earliest crop plants, whose domestication parallelled that of cereals: Soybean in China; faba bean, lentil, chickpea and pea in the Fertile Crescent of the Near East; cowpeas and bambara groundnut in Africa; soybean and mungbeans in East Asia; pigeonpea and the grams in South Asia; and common bean, lima bean, scarlet runner bean, tepary bean and lupin in Central and South America. The importance of legumes is evidenced by their high representation in ex situ germplasm collections, with more than 1,000,000 accessions worldwide. A detailed knowledge of the phylogenetic relationships of the Fabaceae is essential for understanding the origin and diversification of this economically and ecologically important family of angiosperms. This review aims to combine the phylogenetic and genetic diversity approaches to better illustrate the origin, domestication history and preserved germplasm of major legume crops from 13 genera of six tribes and to indicate further potential both for science and agriculture.