Humans have been tinkering with wheat for almost 10,000 years, but new tools are becoming available for manipulation.
As well as the human genome, a draft of which was completed in 2000, scientists have tackled everything from rice to the clearhead icefish and the black cottonwood tree. The world’s most widely cultivated crop has taken all this time because it was really difficult; the “Mount Everest” of plant genetics, according to some.
That difficulty arises from the fact that wheat is not one genome but three overlapping and similar ones, the result of natural hybridisation. It is more than five times the size of the human genome and comprises some 107,000 genes (humans have about 24,000). Genomes are generally figured out by breaking them into smaller pieces, sequencing those pieces and then working out how they fit together. With so many similar-looking sequences, the team of researchers, whose findings were reported in Science and whose efforts focused on a variety of bread wheat called Chinese Spring, had a huge job on their hands.
Their achievement comes at an opportune time. Humans have been tinkering with wheat for almost 10,000 years, but new tools are becoming available for the precise manipulation of genomes. Gene-editing using a technique called CRISPR, along with a fully annotated genetic sequence, promises a new era in wheat cultivation, introducing traits to improve yields, provide greater pest resistance and to develop hardier varieties.
Of particular interest will be how decoding the genes might contribute to understanding, and perhaps even mitigating, various immune diseases and allergies associated with eating bread. This possibility is explored by Angela Juhász of Murdoch University, in Western Australia, and her colleagues in an associated paper in Science Advances.
Coeliac disease, for instance, is an immune reaction to eating gluten; the related genes are the glutenins and gliadins that are expressed in the starchy endosperm of the wheat grain.
Those who have trouble with gluten may find, however, that the source of their problem lies more in the processing of bread rather than the genetics of wheat.
Fermented bread may have fewer of these hard-to-digest bits. Now that scientists have the genome, such theories should be easier to prove.