Digitaria exilis, also known as fonio or fonio millet, is a small annual crop that grows in West Africa.
Cultivation zones of fonio (© J-F Cruz, Cirad according to R. Porteres)
It varies between 30-80cm in height, and is a grassy plant that forms spikelets where the grains are formed. Fonio is extremely drought resistant, and can be grown on soil too arid for other plants. As a result, it is often planted in rotation with other crops such as rice and sorghum.
Fonio is harvested by hand using traditional methods: dried in the sun and then processed by threshing, winnowing, and hulling. Threshing is the process of separating grains from the corn, and can be done by flailing, trampling underfoot, beating with a stick, or (when the resources are available) being crushed under a tractor. Winnowing is done by blowing air through the grains to remove impurities, and can be carried out by pouring the grains from one container to another from a height (e.g. from standing). Hulling is the action of crushing the grain in a pestle and mortar, then sieving it to remove further impurities. The grain can be hulled 3-4 times, or more to produce white fonio.
It is eaten as porridge or a couscous, and can be mixed with other cereals. They can also be used to brew beer, and the straw produced serves as animal feed. Fonio’s entire genome has been sequenced, allowing future research to be made into modifications to enhance the plant and fix any problems that have been observed.
Some of these include that the plant is prone to shattering and the grains are relatively small, giving a smaller yield per surface area. Furthermore, fonio is vulnerable to the pangola stunt virus (PaSV), which causes stunted growth, yellowing, twisting and kinking of young leaves and flowers, as well as swelling of the leaves’ veins. This virus is transmitted by the whitebacked planthopper (Sogatella furcifera) which is a difficult pest to control, usually using insecticidal soap, often with little success.
Genetic engineering can replace these undesirable traits with ones that are more useful to us. For example, Transvala digitgrass is a plant that has been found to be resistant to PaSV. If this was investigated further, it could be possible to find the protein and then the gene responsible for this resistance, and to use CRISPR-cas9 to implant the gene into the fonio genome. This would therefore make PaSV resistant fonio plants and ensure a safe harvest. Following this procedure for other traits, it is possible to create a super strain of fonio that could be sturdier than the ancestral strain, resistant to many diseases of concern and have a greater yield of bigger grains.
Fonio is just one example of a potential GMO crop. Other examples of modifications include Golden Rice, for a supplement of vitamin A, and tomatoes with viral antibodies for an increased immunity to the consumer. There are many more ways that genetic engineering can continue to benefit humanity in the form of GMO crops.
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