Evolution of Wild Barley and Barley Improvement

摘要

Wild barley, Hordeum spontaneum, the progenitor of cultivated barley, Hordeum vulgare, originated 5.5 million years ago in southwest Asia, is distributed in the eastern Mediterranean, Balkans, North Africa, central Asia and Tibet. H. vulgare, the fourth important world crop, used for animal feed, beer, and human food was domesticated polyphyletically by humans 10,000 years ago in the Neolithic revolution in at least three centers: Fertile Crescent, Central Asia, and Tibet of China. H. vulgare with thousands of land races and cultivars, is widespread where other crops can't adapt, yet it deteriorated genetically, especially due to pure breeding, and needs genetic reinforcement. H. spontaneum, the best hope for barley improvement, is a hardy ecological generalist, adapted to a wide range of extreme latitudes, altitudes, climates (warm and cold), and soils. Adaptations occur at all levels: genomically, proteomically, and phenomically both regionally and locally. It displays "archipelago" genetic structure, rich genetically, and harbors immense adaptive abiotic and biotic resistances precious to barley and cereal improvement. Sequencing the H. spontaneum genome will reveal huge, mostly untapped, genetic resources. The current global warming stresses H. spontaneum, and so it is imperative to conserve it in situ and ex situ to safeguard its future immense contribution to barley and cereal improvement, thereby helping to fight hunger.