Bread wheat carries six chromosome sets inherited from three different grasses
The wheat in nearly every loaf is an accidental hybrid. About 8,000 years ago, a farmed wheat crossed with a wild goatgrass near the Caspian Sea, producing a plant with six sets of chromosomes. That species, common wheat, now makes up roughly 95 percent of all wheat and is the world's most widely grown crop.
Its ancestry is a stack of mergers. First, wild einkorn crossed with a goatgrass called Aegilops speltoides, doubling up into wild emmer with four chromosome sets. Much later, domesticated free-threshing emmer-type wheat met another wild goatgrass, Aegilops tauschii, in the South Caucasus or southwest Caspian region, adding two more sets. Genes from that second goatgrass give bread wheat unusual cold hardiness, one reason it thrives across temperate lands everywhere. Human selection produced so many forms that wheat naming remains a tangle.
After domestication it spread in prehistoric times to North Africa, Europe and East Asia, and naked wheats turn up in Roman burials dated between 100 BCE and 300 CE. Spanish missions brought it to North America in the sixteenth century, but the continent became a grain giant only after prairie settlement in the 1870s. When Russian exports stopped during the First World War, Kansas doubled its output. Because it suits industrial baking so well, bread wheat has pushed aside many other wheats, barleys and ryes once used for bread, especially in Europe.
Modern plants are deliberately short. In the 1960s Norman Borlaug bred in dwarfing genes from the Japanese Norin 10 wheat, which blunt the plant's response to a hormone that stretches cells. Without them, heavy fertiliser makes stems shoot up and collapse, a problem called lodging, and even heights make machine harvesting easier. Club wheats, with tightly packed ears, are close enough kin to count as subspecies.
Wheat allergy is an immune reaction that can involve many proteins, not only the gluten components gliadin and glutenin but enzyme inhibitors and hundreds of others. Commercially, no cereal earns more per harvest.
Source: Common wheat
