Abstract

Wheat seeds, known as grain, are a primary source of calories for the human race, and for animal feed, with more than 650 million tonnes being produced annually, worldwide. There are two agricultural species, bread wheat (Triticum aestivum) and durum (pasta) wheat (Triticum durum), both of which belong to the botanical tribe Triticeae in the grass family Poaceae, which also contains the related crop species, rye and barley. The centre of origin of the species is the ‘fertile crescent’ in the Middle East from where they have travelled to all continents of the world, although typically they are major annual crops of the temperate regions. The dried grains are crushed to produce flour, which is mixed by adding water and other ingredients to make dough, which is then cooked to produce a variety of breads and cakes.

Key Concepts:

• Wheat belongs to the botanical tribe Triticeae in the grass family Poaceae, which also contains the related crop species, rye and barley.

• Because of the relatively close genetic relationships between cultivated wheat and related species, it is possible to artificially hybridise cultivated wheat with many of their wild relatives to create hybrids for gene transfer, and even new cereal species, such as Triticale, the artificial hybrid between wheat and rye.

• Triticum turgidum subspecies durum (durum wheat) is atetraploid wheat with 14 pairs of chromosomes (2n=2x=28; AABB genomes) and was domesticated by ancient farmers from a wild species still growing in the Middle East, called Triticum dicoccoides.

• Bread wheat is a hexaploid species (2n=6x=42; AABBDD genomes) with 21 pairs of chromosomes.

• Bread wheat is the most widely grown species of the cultivated wheat species and accounts for approximately 30% of all the cereal grain consumed in the world today, 650 million tonnes were produced in 2010, and it ranks alongside rice and maize as the world's most important crops.

• Most archaeological evidence suggests that the earliest domestication of wheat occurred around 7500–6500 BC in the ‘Fertile Crescent’ consisting of mountain chains flanking the plains of Mesopotamia and the Syrian Desert.

• Evidence suggests that wheat first reached Europe via the south‐east Balkans and spread by two main routes across Europe, one inland and the other coastal.

• The major production areas are now in Europe, Russia, North and South America, Australia and China.

• As a foodstuff for humans, wheat is distinguished from other cereals by its property of making viscoelastic dough when the ground seeds (flour) are mixed with water.

Keywords: cereals; grain; polyploid; fertile crescent; einkorn; emmer; durum; bread; pasta